obj-$(CONFIG_KEXEC_FILE) += kexec_file.o
obj-$(CONFIG_BACKTRACE_SELF_TEST) += backtracetest.o
obj-$(CONFIG_COMPAT) += compat.o
-obj-$(CONFIG_CGROUPS) += cgroup.o
-obj-$(CONFIG_CGROUP_FREEZER) += cgroup_freezer.o
-obj-$(CONFIG_CGROUP_PIDS) += cgroup_pids.o
-obj-$(CONFIG_CPUSETS) += cpuset.o
+obj-$(CONFIG_CGROUPS) += cgroup/
obj-$(CONFIG_UTS_NS) += utsname.o
obj-$(CONFIG_USER_NS) += user_namespace.o
obj-$(CONFIG_PID_NS) += pid_namespace.o
+++ /dev/null
-/*
- * Generic process-grouping system.
- *
- * Based originally on the cpuset system, extracted by Paul Menage
- * Copyright (C) 2006 Google, Inc
- *
- * Notifications support
- * Copyright (C) 2009 Nokia Corporation
- * Author: Kirill A. Shutemov
- *
- * Copyright notices from the original cpuset code:
- * --------------------------------------------------
- * Copyright (C) 2003 BULL SA.
- * Copyright (C) 2004-2006 Silicon Graphics, Inc.
- *
- * Portions derived from Patrick Mochel's sysfs code.
- * sysfs is Copyright (c) 2001-3 Patrick Mochel
- *
- * 2003-10-10 Written by Simon Derr.
- * 2003-10-22 Updates by Stephen Hemminger.
- * 2004 May-July Rework by Paul Jackson.
- * ---------------------------------------------------
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file COPYING in the main directory of the Linux
- * distribution for more details.
- */
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/cgroup.h>
-#include <linux/cred.h>
-#include <linux/ctype.h>
-#include <linux/errno.h>
-#include <linux/init_task.h>
-#include <linux/kernel.h>
-#include <linux/list.h>
-#include <linux/magic.h>
-#include <linux/mm.h>
-#include <linux/mutex.h>
-#include <linux/mount.h>
-#include <linux/pagemap.h>
-#include <linux/proc_fs.h>
-#include <linux/rcupdate.h>
-#include <linux/sched.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/percpu-rwsem.h>
-#include <linux/string.h>
-#include <linux/sort.h>
-#include <linux/kmod.h>
-#include <linux/delayacct.h>
-#include <linux/cgroupstats.h>
-#include <linux/hashtable.h>
-#include <linux/pid_namespace.h>
-#include <linux/idr.h>
-#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
-#include <linux/kthread.h>
-#include <linux/delay.h>
-#include <linux/atomic.h>
-#include <linux/cpuset.h>
-#include <linux/proc_ns.h>
-#include <linux/nsproxy.h>
-#include <linux/file.h>
-#include <net/sock.h>
-
-#define CREATE_TRACE_POINTS
-#include <trace/events/cgroup.h>
-
-/*
- * pidlists linger the following amount before being destroyed. The goal
- * is avoiding frequent destruction in the middle of consecutive read calls
- * Expiring in the middle is a performance problem not a correctness one.
- * 1 sec should be enough.
- */
-#define CGROUP_PIDLIST_DESTROY_DELAY HZ
-
-#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
- MAX_CFTYPE_NAME + 2)
-
-/*
- * cgroup_mutex is the master lock. Any modification to cgroup or its
- * hierarchy must be performed while holding it.
- *
- * css_set_lock protects task->cgroups pointer, the list of css_set
- * objects, and the chain of tasks off each css_set.
- *
- * These locks are exported if CONFIG_PROVE_RCU so that accessors in
- * cgroup.h can use them for lockdep annotations.
- */
-#ifdef CONFIG_PROVE_RCU
-DEFINE_MUTEX(cgroup_mutex);
-DEFINE_SPINLOCK(css_set_lock);
-EXPORT_SYMBOL_GPL(cgroup_mutex);
-EXPORT_SYMBOL_GPL(css_set_lock);
-#else
-static DEFINE_MUTEX(cgroup_mutex);
-static DEFINE_SPINLOCK(css_set_lock);
-#endif
-
-/*
- * Protects cgroup_idr and css_idr so that IDs can be released without
- * grabbing cgroup_mutex.
- */
-static DEFINE_SPINLOCK(cgroup_idr_lock);
-
-/*
- * Protects cgroup_file->kn for !self csses. It synchronizes notifications
- * against file removal/re-creation across css hiding.
- */
-static DEFINE_SPINLOCK(cgroup_file_kn_lock);
-
-/*
- * Protects cgroup_subsys->release_agent_path. Modifying it also requires
- * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
- */
-static DEFINE_SPINLOCK(release_agent_path_lock);
-
-struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
-
-#define cgroup_assert_mutex_or_rcu_locked() \
- RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
- !lockdep_is_held(&cgroup_mutex), \
- "cgroup_mutex or RCU read lock required");
-
-/*
- * cgroup destruction makes heavy use of work items and there can be a lot
- * of concurrent destructions. Use a separate workqueue so that cgroup
- * destruction work items don't end up filling up max_active of system_wq
- * which may lead to deadlock.
- */
-static struct workqueue_struct *cgroup_destroy_wq;
-
-/*
- * pidlist destructions need to be flushed on cgroup destruction. Use a
- * separate workqueue as flush domain.
- */
-static struct workqueue_struct *cgroup_pidlist_destroy_wq;
-
-/* generate an array of cgroup subsystem pointers */
-#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
-static struct cgroup_subsys *cgroup_subsys[] = {
-#include <linux/cgroup_subsys.h>
-};
-#undef SUBSYS
-
-/* array of cgroup subsystem names */
-#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
-static const char *cgroup_subsys_name[] = {
-#include <linux/cgroup_subsys.h>
-};
-#undef SUBSYS
-
-/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
-#define SUBSYS(_x) \
- DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
- DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
- EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
- EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
-#include <linux/cgroup_subsys.h>
-#undef SUBSYS
-
-#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
-static struct static_key_true *cgroup_subsys_enabled_key[] = {
-#include <linux/cgroup_subsys.h>
-};
-#undef SUBSYS
-
-#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
-static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
-#include <linux/cgroup_subsys.h>
-};
-#undef SUBSYS
-
-/*
- * The default hierarchy, reserved for the subsystems that are otherwise
- * unattached - it never has more than a single cgroup, and all tasks are
- * part of that cgroup.
- */
-struct cgroup_root cgrp_dfl_root;
-EXPORT_SYMBOL_GPL(cgrp_dfl_root);
-
-/*
- * The default hierarchy always exists but is hidden until mounted for the
- * first time. This is for backward compatibility.
- */
-static bool cgrp_dfl_visible;
-
-/* Controllers blocked by the commandline in v1 */
-static u16 cgroup_no_v1_mask;
-
-/* some controllers are not supported in the default hierarchy */
-static u16 cgrp_dfl_inhibit_ss_mask;
-
-/* some controllers are implicitly enabled on the default hierarchy */
-static unsigned long cgrp_dfl_implicit_ss_mask;
-
-/* The list of hierarchy roots */
-
-static LIST_HEAD(cgroup_roots);
-static int cgroup_root_count;
-
-/* hierarchy ID allocation and mapping, protected by cgroup_mutex */
-static DEFINE_IDR(cgroup_hierarchy_idr);
-
-/*
- * Assign a monotonically increasing serial number to csses. It guarantees
- * cgroups with bigger numbers are newer than those with smaller numbers.
- * Also, as csses are always appended to the parent's ->children list, it
- * guarantees that sibling csses are always sorted in the ascending serial
- * number order on the list. Protected by cgroup_mutex.
- */
-static u64 css_serial_nr_next = 1;
-
-/*
- * These bitmask flags indicate whether tasks in the fork and exit paths have
- * fork/exit handlers to call. This avoids us having to do extra work in the
- * fork/exit path to check which subsystems have fork/exit callbacks.
- */
-static u16 have_fork_callback __read_mostly;
-static u16 have_exit_callback __read_mostly;
-static u16 have_free_callback __read_mostly;
-
-/* cgroup namespace for init task */
-struct cgroup_namespace init_cgroup_ns = {
- .count = { .counter = 2, },
- .user_ns = &init_user_ns,
- .ns.ops = &cgroupns_operations,
- .ns.inum = PROC_CGROUP_INIT_INO,
- .root_cset = &init_css_set,
-};
-
-/* Ditto for the can_fork callback. */
-static u16 have_canfork_callback __read_mostly;
-
-static struct file_system_type cgroup2_fs_type;
-static struct cftype cgroup_dfl_base_files[];
-static struct cftype cgroup_legacy_base_files[];
-
-static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
-static void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
-static int cgroup_apply_control(struct cgroup *cgrp);
-static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
-static void css_task_iter_advance(struct css_task_iter *it);
-static int cgroup_destroy_locked(struct cgroup *cgrp);
-static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
- struct cgroup_subsys *ss);
-static void css_release(struct percpu_ref *ref);
-static void kill_css(struct cgroup_subsys_state *css);
-static int cgroup_addrm_files(struct cgroup_subsys_state *css,
- struct cgroup *cgrp, struct cftype cfts[],
- bool is_add);
-
-/**
- * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
- * @ssid: subsys ID of interest
- *
- * cgroup_subsys_enabled() can only be used with literal subsys names which
- * is fine for individual subsystems but unsuitable for cgroup core. This
- * is slower static_key_enabled() based test indexed by @ssid.
- */
-static bool cgroup_ssid_enabled(int ssid)
-{
- if (CGROUP_SUBSYS_COUNT == 0)
- return false;
-
- return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
-}
-
-static bool cgroup_ssid_no_v1(int ssid)
-{
- return cgroup_no_v1_mask & (1 << ssid);
-}
-
-/**
- * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
- * @cgrp: the cgroup of interest
- *
- * The default hierarchy is the v2 interface of cgroup and this function
- * can be used to test whether a cgroup is on the default hierarchy for
- * cases where a subsystem should behave differnetly depending on the
- * interface version.
- *
- * The set of behaviors which change on the default hierarchy are still
- * being determined and the mount option is prefixed with __DEVEL__.
- *
- * List of changed behaviors:
- *
- * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
- * and "name" are disallowed.
- *
- * - When mounting an existing superblock, mount options should match.
- *
- * - Remount is disallowed.
- *
- * - rename(2) is disallowed.
- *
- * - "tasks" is removed. Everything should be at process granularity. Use
- * "cgroup.procs" instead.
- *
- * - "cgroup.procs" is not sorted. pids will be unique unless they got
- * recycled inbetween reads.
- *
- * - "release_agent" and "notify_on_release" are removed. Replacement
- * notification mechanism will be implemented.
- *
- * - "cgroup.clone_children" is removed.
- *
- * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
- * and its descendants contain no task; otherwise, 1. The file also
- * generates kernfs notification which can be monitored through poll and
- * [di]notify when the value of the file changes.
- *
- * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
- * take masks of ancestors with non-empty cpus/mems, instead of being
- * moved to an ancestor.
- *
- * - cpuset: a task can be moved into an empty cpuset, and again it takes
- * masks of ancestors.
- *
- * - memcg: use_hierarchy is on by default and the cgroup file for the flag
- * is not created.
- *
- * - blkcg: blk-throttle becomes properly hierarchical.
- *
- * - debug: disallowed on the default hierarchy.
- */
-static bool cgroup_on_dfl(const struct cgroup *cgrp)
-{
- return cgrp->root == &cgrp_dfl_root;
-}
-
-/* IDR wrappers which synchronize using cgroup_idr_lock */
-static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
- gfp_t gfp_mask)
-{
- int ret;
-
- idr_preload(gfp_mask);
- spin_lock_bh(&cgroup_idr_lock);
- ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
- spin_unlock_bh(&cgroup_idr_lock);
- idr_preload_end();
- return ret;
-}
-
-static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
-{
- void *ret;
-
- spin_lock_bh(&cgroup_idr_lock);
- ret = idr_replace(idr, ptr, id);
- spin_unlock_bh(&cgroup_idr_lock);
- return ret;
-}
-
-static void cgroup_idr_remove(struct idr *idr, int id)
-{
- spin_lock_bh(&cgroup_idr_lock);
- idr_remove(idr, id);
- spin_unlock_bh(&cgroup_idr_lock);
-}
-
-static struct cgroup *cgroup_parent(struct cgroup *cgrp)
-{
- struct cgroup_subsys_state *parent_css = cgrp->self.parent;
-
- if (parent_css)
- return container_of(parent_css, struct cgroup, self);
- return NULL;
-}
-
-/* subsystems visibly enabled on a cgroup */
-static u16 cgroup_control(struct cgroup *cgrp)
-{
- struct cgroup *parent = cgroup_parent(cgrp);
- u16 root_ss_mask = cgrp->root->subsys_mask;
-
- if (parent)
- return parent->subtree_control;
-
- if (cgroup_on_dfl(cgrp))
- root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
- cgrp_dfl_implicit_ss_mask);
- return root_ss_mask;
-}
-
-/* subsystems enabled on a cgroup */
-static u16 cgroup_ss_mask(struct cgroup *cgrp)
-{
- struct cgroup *parent = cgroup_parent(cgrp);
-
- if (parent)
- return parent->subtree_ss_mask;
-
- return cgrp->root->subsys_mask;
-}
-
-/**
- * cgroup_css - obtain a cgroup's css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns @cgrp->self)
- *
- * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
- * function must be called either under cgroup_mutex or rcu_read_lock() and
- * the caller is responsible for pinning the returned css if it wants to
- * keep accessing it outside the said locks. This function may return
- * %NULL if @cgrp doesn't have @subsys_id enabled.
- */
-static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
-{
- if (ss)
- return rcu_dereference_check(cgrp->subsys[ss->id],
- lockdep_is_held(&cgroup_mutex));
- else
- return &cgrp->self;
-}
-
-/**
- * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest (%NULL returns @cgrp->self)
- *
- * Similar to cgroup_css() but returns the effective css, which is defined
- * as the matching css of the nearest ancestor including self which has @ss
- * enabled. If @ss is associated with the hierarchy @cgrp is on, this
- * function is guaranteed to return non-NULL css.
- */
-static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
-{
- lockdep_assert_held(&cgroup_mutex);
-
- if (!ss)
- return &cgrp->self;
-
- /*
- * This function is used while updating css associations and thus
- * can't test the csses directly. Test ss_mask.
- */
- while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) {
- cgrp = cgroup_parent(cgrp);
- if (!cgrp)
- return NULL;
- }
-
- return cgroup_css(cgrp, ss);
-}
-
-/**
- * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
- * @cgrp: the cgroup of interest
- * @ss: the subsystem of interest
- *
- * Find and get the effective css of @cgrp for @ss. The effective css is
- * defined as the matching css of the nearest ancestor including self which
- * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
- * the root css is returned, so this function always returns a valid css.
- * The returned css must be put using css_put().
- */
-struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
-{
- struct cgroup_subsys_state *css;
-
- rcu_read_lock();
-
- do {
- css = cgroup_css(cgrp, ss);
-
- if (css && css_tryget_online(css))
- goto out_unlock;
- cgrp = cgroup_parent(cgrp);
- } while (cgrp);
-
- css = init_css_set.subsys[ss->id];
- css_get(css);
-out_unlock:
- rcu_read_unlock();
- return css;
-}
-
-/* convenient tests for these bits */
-static inline bool cgroup_is_dead(const struct cgroup *cgrp)
-{
- return !(cgrp->self.flags & CSS_ONLINE);
-}
-
-static void cgroup_get(struct cgroup *cgrp)
-{
- WARN_ON_ONCE(cgroup_is_dead(cgrp));
- css_get(&cgrp->self);
-}
-
-static bool cgroup_tryget(struct cgroup *cgrp)
-{
- return css_tryget(&cgrp->self);
-}
-
-struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
-{
- struct cgroup *cgrp = of->kn->parent->priv;
- struct cftype *cft = of_cft(of);
-
- /*
- * This is open and unprotected implementation of cgroup_css().
- * seq_css() is only called from a kernfs file operation which has
- * an active reference on the file. Because all the subsystem
- * files are drained before a css is disassociated with a cgroup,
- * the matching css from the cgroup's subsys table is guaranteed to
- * be and stay valid until the enclosing operation is complete.
- */
- if (cft->ss)
- return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
- else
- return &cgrp->self;
-}
-EXPORT_SYMBOL_GPL(of_css);
-
-static int notify_on_release(const struct cgroup *cgrp)
-{
- return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
-}
-
-/**
- * for_each_css - iterate all css's of a cgroup
- * @css: the iteration cursor
- * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
- * @cgrp: the target cgroup to iterate css's of
- *
- * Should be called under cgroup_[tree_]mutex.
- */
-#define for_each_css(css, ssid, cgrp) \
- for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
- if (!((css) = rcu_dereference_check( \
- (cgrp)->subsys[(ssid)], \
- lockdep_is_held(&cgroup_mutex)))) { } \
- else
-
-/**
- * for_each_e_css - iterate all effective css's of a cgroup
- * @css: the iteration cursor
- * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
- * @cgrp: the target cgroup to iterate css's of
- *
- * Should be called under cgroup_[tree_]mutex.
- */
-#define for_each_e_css(css, ssid, cgrp) \
- for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
- if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
- ; \
- else
-
-/**
- * for_each_subsys - iterate all enabled cgroup subsystems
- * @ss: the iteration cursor
- * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
- */
-#define for_each_subsys(ss, ssid) \
- for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
- (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
-
-/**
- * do_each_subsys_mask - filter for_each_subsys with a bitmask
- * @ss: the iteration cursor
- * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
- * @ss_mask: the bitmask
- *
- * The block will only run for cases where the ssid-th bit (1 << ssid) of
- * @ss_mask is set.
- */
-#define do_each_subsys_mask(ss, ssid, ss_mask) do { \
- unsigned long __ss_mask = (ss_mask); \
- if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
- (ssid) = 0; \
- break; \
- } \
- for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
- (ss) = cgroup_subsys[ssid]; \
- {
-
-#define while_each_subsys_mask() \
- } \
- } \
-} while (false)
-
-/* iterate across the hierarchies */
-#define for_each_root(root) \
- list_for_each_entry((root), &cgroup_roots, root_list)
-
-/* iterate over child cgrps, lock should be held throughout iteration */
-#define cgroup_for_each_live_child(child, cgrp) \
- list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
- if (({ lockdep_assert_held(&cgroup_mutex); \
- cgroup_is_dead(child); })) \
- ; \
- else
-
-/* walk live descendants in preorder */
-#define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
- css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
- if (({ lockdep_assert_held(&cgroup_mutex); \
- (dsct) = (d_css)->cgroup; \
- cgroup_is_dead(dsct); })) \
- ; \
- else
-
-/* walk live descendants in postorder */
-#define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
- css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
- if (({ lockdep_assert_held(&cgroup_mutex); \
- (dsct) = (d_css)->cgroup; \
- cgroup_is_dead(dsct); })) \
- ; \
- else
-
-static void cgroup_release_agent(struct work_struct *work);
-static void check_for_release(struct cgroup *cgrp);
-
-/*
- * A cgroup can be associated with multiple css_sets as different tasks may
- * belong to different cgroups on different hierarchies. In the other
- * direction, a css_set is naturally associated with multiple cgroups.
- * This M:N relationship is represented by the following link structure
- * which exists for each association and allows traversing the associations
- * from both sides.
- */
-struct cgrp_cset_link {
- /* the cgroup and css_set this link associates */
- struct cgroup *cgrp;
- struct css_set *cset;
-
- /* list of cgrp_cset_links anchored at cgrp->cset_links */
- struct list_head cset_link;
-
- /* list of cgrp_cset_links anchored at css_set->cgrp_links */
- struct list_head cgrp_link;
-};
-
-/*
- * The default css_set - used by init and its children prior to any
- * hierarchies being mounted. It contains a pointer to the root state
- * for each subsystem. Also used to anchor the list of css_sets. Not
- * reference-counted, to improve performance when child cgroups
- * haven't been created.
- */
-struct css_set init_css_set = {
- .refcount = ATOMIC_INIT(1),
- .tasks = LIST_HEAD_INIT(init_css_set.tasks),
- .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
- .task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
- .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
- .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
- .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
-};
-
-static int css_set_count = 1; /* 1 for init_css_set */
-
-/**
- * css_set_populated - does a css_set contain any tasks?
- * @cset: target css_set
- */
-static bool css_set_populated(struct css_set *cset)
-{
- lockdep_assert_held(&css_set_lock);
-
- return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks);
-}
-
-/**
- * cgroup_update_populated - updated populated count of a cgroup
- * @cgrp: the target cgroup
- * @populated: inc or dec populated count
- *
- * One of the css_sets associated with @cgrp is either getting its first
- * task or losing the last. Update @cgrp->populated_cnt accordingly. The
- * count is propagated towards root so that a given cgroup's populated_cnt
- * is zero iff the cgroup and all its descendants don't contain any tasks.
- *
- * @cgrp's interface file "cgroup.populated" is zero if
- * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
- * changes from or to zero, userland is notified that the content of the
- * interface file has changed. This can be used to detect when @cgrp and
- * its descendants become populated or empty.
- */
-static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
-{
- lockdep_assert_held(&css_set_lock);
-
- do {
- bool trigger;
-
- if (populated)
- trigger = !cgrp->populated_cnt++;
- else
- trigger = !--cgrp->populated_cnt;
-
- if (!trigger)
- break;
-
- check_for_release(cgrp);
- cgroup_file_notify(&cgrp->events_file);
-
- cgrp = cgroup_parent(cgrp);
- } while (cgrp);
-}
-
-/**
- * css_set_update_populated - update populated state of a css_set
- * @cset: target css_set
- * @populated: whether @cset is populated or depopulated
- *
- * @cset is either getting the first task or losing the last. Update the
- * ->populated_cnt of all associated cgroups accordingly.
- */
-static void css_set_update_populated(struct css_set *cset, bool populated)
-{
- struct cgrp_cset_link *link;
-
- lockdep_assert_held(&css_set_lock);
-
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link)
- cgroup_update_populated(link->cgrp, populated);
-}
-
-/**
- * css_set_move_task - move a task from one css_set to another
- * @task: task being moved
- * @from_cset: css_set @task currently belongs to (may be NULL)
- * @to_cset: new css_set @task is being moved to (may be NULL)
- * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
- *
- * Move @task from @from_cset to @to_cset. If @task didn't belong to any
- * css_set, @from_cset can be NULL. If @task is being disassociated
- * instead of moved, @to_cset can be NULL.
- *
- * This function automatically handles populated_cnt updates and
- * css_task_iter adjustments but the caller is responsible for managing
- * @from_cset and @to_cset's reference counts.
- */
-static void css_set_move_task(struct task_struct *task,
- struct css_set *from_cset, struct css_set *to_cset,
- bool use_mg_tasks)
-{
- lockdep_assert_held(&css_set_lock);
-
- if (to_cset && !css_set_populated(to_cset))
- css_set_update_populated(to_cset, true);
-
- if (from_cset) {
- struct css_task_iter *it, *pos;
-
- WARN_ON_ONCE(list_empty(&task->cg_list));
-
- /*
- * @task is leaving, advance task iterators which are
- * pointing to it so that they can resume at the next
- * position. Advancing an iterator might remove it from
- * the list, use safe walk. See css_task_iter_advance*()
- * for details.
- */
- list_for_each_entry_safe(it, pos, &from_cset->task_iters,
- iters_node)
- if (it->task_pos == &task->cg_list)
- css_task_iter_advance(it);
-
- list_del_init(&task->cg_list);
- if (!css_set_populated(from_cset))
- css_set_update_populated(from_cset, false);
- } else {
- WARN_ON_ONCE(!list_empty(&task->cg_list));
- }
-
- if (to_cset) {
- /*
- * We are synchronized through cgroup_threadgroup_rwsem
- * against PF_EXITING setting such that we can't race
- * against cgroup_exit() changing the css_set to
- * init_css_set and dropping the old one.
- */
- WARN_ON_ONCE(task->flags & PF_EXITING);
-
- rcu_assign_pointer(task->cgroups, to_cset);
- list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
- &to_cset->tasks);
- }
-}
-
-/*
- * hash table for cgroup groups. This improves the performance to find
- * an existing css_set. This hash doesn't (currently) take into
- * account cgroups in empty hierarchies.
- */
-#define CSS_SET_HASH_BITS 7
-static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
-
-static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
-{
- unsigned long key = 0UL;
- struct cgroup_subsys *ss;
- int i;
-
- for_each_subsys(ss, i)
- key += (unsigned long)css[i];
- key = (key >> 16) ^ key;
-
- return key;
-}
-
-static void put_css_set_locked(struct css_set *cset)
-{
- struct cgrp_cset_link *link, *tmp_link;
- struct cgroup_subsys *ss;
- int ssid;
-
- lockdep_assert_held(&css_set_lock);
-
- if (!atomic_dec_and_test(&cset->refcount))
- return;
-
- /* This css_set is dead. unlink it and release cgroup and css refs */
- for_each_subsys(ss, ssid) {
- list_del(&cset->e_cset_node[ssid]);
- css_put(cset->subsys[ssid]);
- }
- hash_del(&cset->hlist);
- css_set_count--;
-
- list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
- list_del(&link->cset_link);
- list_del(&link->cgrp_link);
- if (cgroup_parent(link->cgrp))
- cgroup_put(link->cgrp);
- kfree(link);
- }
-
- kfree_rcu(cset, rcu_head);
-}
-
-static void put_css_set(struct css_set *cset)
-{
- unsigned long flags;
-
- /*
- * Ensure that the refcount doesn't hit zero while any readers
- * can see it. Similar to atomic_dec_and_lock(), but for an
- * rwlock
- */
- if (atomic_add_unless(&cset->refcount, -1, 1))
- return;
-
- spin_lock_irqsave(&css_set_lock, flags);
- put_css_set_locked(cset);
- spin_unlock_irqrestore(&css_set_lock, flags);
-}
-
-/*
- * refcounted get/put for css_set objects
- */
-static inline void get_css_set(struct css_set *cset)
-{
- atomic_inc(&cset->refcount);
-}
-
-/**
- * compare_css_sets - helper function for find_existing_css_set().
- * @cset: candidate css_set being tested
- * @old_cset: existing css_set for a task
- * @new_cgrp: cgroup that's being entered by the task
- * @template: desired set of css pointers in css_set (pre-calculated)
- *
- * Returns true if "cset" matches "old_cset" except for the hierarchy
- * which "new_cgrp" belongs to, for which it should match "new_cgrp".
- */
-static bool compare_css_sets(struct css_set *cset,
- struct css_set *old_cset,
- struct cgroup *new_cgrp,
- struct cgroup_subsys_state *template[])
-{
- struct list_head *l1, *l2;
-
- /*
- * On the default hierarchy, there can be csets which are
- * associated with the same set of cgroups but different csses.
- * Let's first ensure that csses match.
- */
- if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
- return false;
-
- /*
- * Compare cgroup pointers in order to distinguish between
- * different cgroups in hierarchies. As different cgroups may
- * share the same effective css, this comparison is always
- * necessary.
- */
- l1 = &cset->cgrp_links;
- l2 = &old_cset->cgrp_links;
- while (1) {
- struct cgrp_cset_link *link1, *link2;
- struct cgroup *cgrp1, *cgrp2;
-
- l1 = l1->next;
- l2 = l2->next;
- /* See if we reached the end - both lists are equal length. */
- if (l1 == &cset->cgrp_links) {
- BUG_ON(l2 != &old_cset->cgrp_links);
- break;
- } else {
- BUG_ON(l2 == &old_cset->cgrp_links);
- }
- /* Locate the cgroups associated with these links. */
- link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
- link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
- cgrp1 = link1->cgrp;
- cgrp2 = link2->cgrp;
- /* Hierarchies should be linked in the same order. */
- BUG_ON(cgrp1->root != cgrp2->root);
-
- /*
- * If this hierarchy is the hierarchy of the cgroup
- * that's changing, then we need to check that this
- * css_set points to the new cgroup; if it's any other
- * hierarchy, then this css_set should point to the
- * same cgroup as the old css_set.
- */
- if (cgrp1->root == new_cgrp->root) {
- if (cgrp1 != new_cgrp)
- return false;
- } else {
- if (cgrp1 != cgrp2)
- return false;
- }
- }
- return true;
-}
-
-/**
- * find_existing_css_set - init css array and find the matching css_set
- * @old_cset: the css_set that we're using before the cgroup transition
- * @cgrp: the cgroup that we're moving into
- * @template: out param for the new set of csses, should be clear on entry
- */
-static struct css_set *find_existing_css_set(struct css_set *old_cset,
- struct cgroup *cgrp,
- struct cgroup_subsys_state *template[])
-{
- struct cgroup_root *root = cgrp->root;
- struct cgroup_subsys *ss;
- struct css_set *cset;
- unsigned long key;
- int i;
-
- /*
- * Build the set of subsystem state objects that we want to see in the
- * new css_set. while subsystems can change globally, the entries here
- * won't change, so no need for locking.
- */
- for_each_subsys(ss, i) {
- if (root->subsys_mask & (1UL << i)) {
- /*
- * @ss is in this hierarchy, so we want the
- * effective css from @cgrp.
- */
- template[i] = cgroup_e_css(cgrp, ss);
- } else {
- /*
- * @ss is not in this hierarchy, so we don't want
- * to change the css.
- */
- template[i] = old_cset->subsys[i];
- }
- }
-
- key = css_set_hash(template);
- hash_for_each_possible(css_set_table, cset, hlist, key) {
- if (!compare_css_sets(cset, old_cset, cgrp, template))
- continue;
-
- /* This css_set matches what we need */
- return cset;
- }
-
- /* No existing cgroup group matched */
- return NULL;
-}
-
-static void free_cgrp_cset_links(struct list_head *links_to_free)
-{
- struct cgrp_cset_link *link, *tmp_link;
-
- list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
- list_del(&link->cset_link);
- kfree(link);
- }
-}
-
-/**
- * allocate_cgrp_cset_links - allocate cgrp_cset_links
- * @count: the number of links to allocate
- * @tmp_links: list_head the allocated links are put on
- *
- * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
- * through ->cset_link. Returns 0 on success or -errno.
- */
-static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
-{
- struct cgrp_cset_link *link;
- int i;
-
- INIT_LIST_HEAD(tmp_links);
-
- for (i = 0; i < count; i++) {
- link = kzalloc(sizeof(*link), GFP_KERNEL);
- if (!link) {
- free_cgrp_cset_links(tmp_links);
- return -ENOMEM;
- }
- list_add(&link->cset_link, tmp_links);
- }
- return 0;
-}
-
-/**
- * link_css_set - a helper function to link a css_set to a cgroup
- * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
- * @cset: the css_set to be linked
- * @cgrp: the destination cgroup
- */
-static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
- struct cgroup *cgrp)
-{
- struct cgrp_cset_link *link;
-
- BUG_ON(list_empty(tmp_links));
-
- if (cgroup_on_dfl(cgrp))
- cset->dfl_cgrp = cgrp;
-
- link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
- link->cset = cset;
- link->cgrp = cgrp;
-
- /*
- * Always add links to the tail of the lists so that the lists are
- * in choronological order.
- */
- list_move_tail(&link->cset_link, &cgrp->cset_links);
- list_add_tail(&link->cgrp_link, &cset->cgrp_links);
-
- if (cgroup_parent(cgrp))
- cgroup_get(cgrp);
-}
-
-/**
- * find_css_set - return a new css_set with one cgroup updated
- * @old_cset: the baseline css_set
- * @cgrp: the cgroup to be updated
- *
- * Return a new css_set that's equivalent to @old_cset, but with @cgrp
- * substituted into the appropriate hierarchy.
- */
-static struct css_set *find_css_set(struct css_set *old_cset,
- struct cgroup *cgrp)
-{
- struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
- struct css_set *cset;
- struct list_head tmp_links;
- struct cgrp_cset_link *link;
- struct cgroup_subsys *ss;
- unsigned long key;
- int ssid;
-
- lockdep_assert_held(&cgroup_mutex);
-
- /* First see if we already have a cgroup group that matches
- * the desired set */
- spin_lock_irq(&css_set_lock);
- cset = find_existing_css_set(old_cset, cgrp, template);
- if (cset)
- get_css_set(cset);
- spin_unlock_irq(&css_set_lock);
-
- if (cset)
- return cset;
-
- cset = kzalloc(sizeof(*cset), GFP_KERNEL);
- if (!cset)
- return NULL;
-
- /* Allocate all the cgrp_cset_link objects that we'll need */
- if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
- kfree(cset);
- return NULL;
- }
-
- atomic_set(&cset->refcount, 1);
- INIT_LIST_HEAD(&cset->tasks);
- INIT_LIST_HEAD(&cset->mg_tasks);
- INIT_LIST_HEAD(&cset->task_iters);
- INIT_HLIST_NODE(&cset->hlist);
- INIT_LIST_HEAD(&cset->cgrp_links);
- INIT_LIST_HEAD(&cset->mg_preload_node);
- INIT_LIST_HEAD(&cset->mg_node);
-
- /* Copy the set of subsystem state objects generated in
- * find_existing_css_set() */
- memcpy(cset->subsys, template, sizeof(cset->subsys));
-
- spin_lock_irq(&css_set_lock);
- /* Add reference counts and links from the new css_set. */
- list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
-
- if (c->root == cgrp->root)
- c = cgrp;
- link_css_set(&tmp_links, cset, c);
- }
-
- BUG_ON(!list_empty(&tmp_links));
-
- css_set_count++;
-
- /* Add @cset to the hash table */
- key = css_set_hash(cset->subsys);
- hash_add(css_set_table, &cset->hlist, key);
-
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cset->subsys[ssid];
-
- list_add_tail(&cset->e_cset_node[ssid],
- &css->cgroup->e_csets[ssid]);
- css_get(css);
- }
-
- spin_unlock_irq(&css_set_lock);
-
- return cset;
-}
-
-static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
-{
- struct cgroup *root_cgrp = kf_root->kn->priv;
-
- return root_cgrp->root;
-}
-
-static int cgroup_init_root_id(struct cgroup_root *root)
-{
- int id;
-
- lockdep_assert_held(&cgroup_mutex);
-
- id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
- if (id < 0)
- return id;
-
- root->hierarchy_id = id;
- return 0;
-}
-
-static void cgroup_exit_root_id(struct cgroup_root *root)
-{
- lockdep_assert_held(&cgroup_mutex);
-
- idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
-}
-
-static void cgroup_free_root(struct cgroup_root *root)
-{
- if (root) {
- idr_destroy(&root->cgroup_idr);
- kfree(root);
- }
-}
-
-static void cgroup_destroy_root(struct cgroup_root *root)
-{
- struct cgroup *cgrp = &root->cgrp;
- struct cgrp_cset_link *link, *tmp_link;
-
- trace_cgroup_destroy_root(root);
-
- cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
- BUG_ON(atomic_read(&root->nr_cgrps));
- BUG_ON(!list_empty(&cgrp->self.children));
-
- /* Rebind all subsystems back to the default hierarchy */
- WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask));
-
- /*
- * Release all the links from cset_links to this hierarchy's
- * root cgroup
- */
- spin_lock_irq(&css_set_lock);
-
- list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
- list_del(&link->cset_link);
- list_del(&link->cgrp_link);
- kfree(link);
- }
-
- spin_unlock_irq(&css_set_lock);
-
- if (!list_empty(&root->root_list)) {
- list_del(&root->root_list);
- cgroup_root_count--;
- }
-
- cgroup_exit_root_id(root);
-
- mutex_unlock(&cgroup_mutex);
-
- kernfs_destroy_root(root->kf_root);
- cgroup_free_root(root);
-}
-
-/*
- * look up cgroup associated with current task's cgroup namespace on the
- * specified hierarchy
- */
-static struct cgroup *
-current_cgns_cgroup_from_root(struct cgroup_root *root)
-{
- struct cgroup *res = NULL;
- struct css_set *cset;
-
- lockdep_assert_held(&css_set_lock);
-
- rcu_read_lock();
-
- cset = current->nsproxy->cgroup_ns->root_cset;
- if (cset == &init_css_set) {
- res = &root->cgrp;
- } else {
- struct cgrp_cset_link *link;
-
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
-
- if (c->root == root) {
- res = c;
- break;
- }
- }
- }
- rcu_read_unlock();
-
- BUG_ON(!res);
- return res;
-}
-
-/* look up cgroup associated with given css_set on the specified hierarchy */
-static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
- struct cgroup_root *root)
-{
- struct cgroup *res = NULL;
-
- lockdep_assert_held(&cgroup_mutex);
- lockdep_assert_held(&css_set_lock);
-
- if (cset == &init_css_set) {
- res = &root->cgrp;
- } else {
- struct cgrp_cset_link *link;
-
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
-
- if (c->root == root) {
- res = c;
- break;
- }
- }
- }
-
- BUG_ON(!res);
- return res;
-}
-
-/*
- * Return the cgroup for "task" from the given hierarchy. Must be
- * called with cgroup_mutex and css_set_lock held.
- */
-static struct cgroup *task_cgroup_from_root(struct task_struct *task,
- struct cgroup_root *root)
-{
- /*
- * No need to lock the task - since we hold cgroup_mutex the
- * task can't change groups, so the only thing that can happen
- * is that it exits and its css is set back to init_css_set.
- */
- return cset_cgroup_from_root(task_css_set(task), root);
-}
-
-/*
- * A task must hold cgroup_mutex to modify cgroups.
- *
- * Any task can increment and decrement the count field without lock.
- * So in general, code holding cgroup_mutex can't rely on the count
- * field not changing. However, if the count goes to zero, then only
- * cgroup_attach_task() can increment it again. Because a count of zero
- * means that no tasks are currently attached, therefore there is no
- * way a task attached to that cgroup can fork (the other way to
- * increment the count). So code holding cgroup_mutex can safely
- * assume that if the count is zero, it will stay zero. Similarly, if
- * a task holds cgroup_mutex on a cgroup with zero count, it
- * knows that the cgroup won't be removed, as cgroup_rmdir()
- * needs that mutex.
- *
- * A cgroup can only be deleted if both its 'count' of using tasks
- * is zero, and its list of 'children' cgroups is empty. Since all
- * tasks in the system use _some_ cgroup, and since there is always at
- * least one task in the system (init, pid == 1), therefore, root cgroup
- * always has either children cgroups and/or using tasks. So we don't
- * need a special hack to ensure that root cgroup cannot be deleted.
- *
- * P.S. One more locking exception. RCU is used to guard the
- * update of a tasks cgroup pointer by cgroup_attach_task()
- */
-
-static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
-static const struct file_operations proc_cgroupstats_operations;
-
-static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
- char *buf)
-{
- struct cgroup_subsys *ss = cft->ss;
-
- if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
- !(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
- snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
- cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
- cft->name);
- else
- strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
- return buf;
-}
-
-/**
- * cgroup_file_mode - deduce file mode of a control file
- * @cft: the control file in question
- *
- * S_IRUGO for read, S_IWUSR for write.
- */
-static umode_t cgroup_file_mode(const struct cftype *cft)
-{
- umode_t mode = 0;
-
- if (cft->read_u64 || cft->read_s64 || cft->seq_show)
- mode |= S_IRUGO;
-
- if (cft->write_u64 || cft->write_s64 || cft->write) {
- if (cft->flags & CFTYPE_WORLD_WRITABLE)
- mode |= S_IWUGO;
- else
- mode |= S_IWUSR;
- }
-
- return mode;
-}
-
-/**
- * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
- * @subtree_control: the new subtree_control mask to consider
- * @this_ss_mask: available subsystems
- *
- * On the default hierarchy, a subsystem may request other subsystems to be
- * enabled together through its ->depends_on mask. In such cases, more
- * subsystems than specified in "cgroup.subtree_control" may be enabled.
- *
- * This function calculates which subsystems need to be enabled if
- * @subtree_control is to be applied while restricted to @this_ss_mask.
- */
-static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
-{
- u16 cur_ss_mask = subtree_control;
- struct cgroup_subsys *ss;
- int ssid;
-
- lockdep_assert_held(&cgroup_mutex);
-
- cur_ss_mask |= cgrp_dfl_implicit_ss_mask;
-
- while (true) {
- u16 new_ss_mask = cur_ss_mask;
-
- do_each_subsys_mask(ss, ssid, cur_ss_mask) {
- new_ss_mask |= ss->depends_on;
- } while_each_subsys_mask();
-
- /*
- * Mask out subsystems which aren't available. This can
- * happen only if some depended-upon subsystems were bound
- * to non-default hierarchies.
- */
- new_ss_mask &= this_ss_mask;
-
- if (new_ss_mask == cur_ss_mask)
- break;
- cur_ss_mask = new_ss_mask;
- }
-
- return cur_ss_mask;
-}
-
-/**
- * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
- * @kn: the kernfs_node being serviced
- *
- * This helper undoes cgroup_kn_lock_live() and should be invoked before
- * the method finishes if locking succeeded. Note that once this function
- * returns the cgroup returned by cgroup_kn_lock_live() may become
- * inaccessible any time. If the caller intends to continue to access the
- * cgroup, it should pin it before invoking this function.
- */
-static void cgroup_kn_unlock(struct kernfs_node *kn)
-{
- struct cgroup *cgrp;
-
- if (kernfs_type(kn) == KERNFS_DIR)
- cgrp = kn->priv;
- else
- cgrp = kn->parent->priv;
-
- mutex_unlock(&cgroup_mutex);
-
- kernfs_unbreak_active_protection(kn);
- cgroup_put(cgrp);
-}
-
-/**
- * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
- * @kn: the kernfs_node being serviced
- * @drain_offline: perform offline draining on the cgroup
- *
- * This helper is to be used by a cgroup kernfs method currently servicing
- * @kn. It breaks the active protection, performs cgroup locking and
- * verifies that the associated cgroup is alive. Returns the cgroup if
- * alive; otherwise, %NULL. A successful return should be undone by a
- * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
- * cgroup is drained of offlining csses before return.
- *
- * Any cgroup kernfs method implementation which requires locking the
- * associated cgroup should use this helper. It avoids nesting cgroup
- * locking under kernfs active protection and allows all kernfs operations
- * including self-removal.
- */
-static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn,
- bool drain_offline)
-{
- struct cgroup *cgrp;
-
- if (kernfs_type(kn) == KERNFS_DIR)
- cgrp = kn->priv;
- else
- cgrp = kn->parent->priv;
-
- /*
- * We're gonna grab cgroup_mutex which nests outside kernfs
- * active_ref. cgroup liveliness check alone provides enough
- * protection against removal. Ensure @cgrp stays accessible and
- * break the active_ref protection.
- */
- if (!cgroup_tryget(cgrp))
- return NULL;
- kernfs_break_active_protection(kn);
-
- if (drain_offline)
- cgroup_lock_and_drain_offline(cgrp);
- else
- mutex_lock(&cgroup_mutex);
-
- if (!cgroup_is_dead(cgrp))
- return cgrp;
-
- cgroup_kn_unlock(kn);
- return NULL;
-}
-
-static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
-{
- char name[CGROUP_FILE_NAME_MAX];
-
- lockdep_assert_held(&cgroup_mutex);
-
- if (cft->file_offset) {
- struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
- struct cgroup_file *cfile = (void *)css + cft->file_offset;
-
- spin_lock_irq(&cgroup_file_kn_lock);
- cfile->kn = NULL;
- spin_unlock_irq(&cgroup_file_kn_lock);
- }
-
- kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
-}
-
-/**
- * css_clear_dir - remove subsys files in a cgroup directory
- * @css: taget css
- */
-static void css_clear_dir(struct cgroup_subsys_state *css)
-{
- struct cgroup *cgrp = css->cgroup;
- struct cftype *cfts;
-
- if (!(css->flags & CSS_VISIBLE))
- return;
-
- css->flags &= ~CSS_VISIBLE;
-
- list_for_each_entry(cfts, &css->ss->cfts, node)
- cgroup_addrm_files(css, cgrp, cfts, false);
-}
-
-/**
- * css_populate_dir - create subsys files in a cgroup directory
- * @css: target css
- *
- * On failure, no file is added.
- */
-static int css_populate_dir(struct cgroup_subsys_state *css)
-{
- struct cgroup *cgrp = css->cgroup;
- struct cftype *cfts, *failed_cfts;
- int ret;
-
- if ((css->flags & CSS_VISIBLE) || !cgrp->kn)
- return 0;
-
- if (!css->ss) {
- if (cgroup_on_dfl(cgrp))
- cfts = cgroup_dfl_base_files;
- else
- cfts = cgroup_legacy_base_files;
-
- return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
- }
-
- list_for_each_entry(cfts, &css->ss->cfts, node) {
- ret = cgroup_addrm_files(css, cgrp, cfts, true);
- if (ret < 0) {
- failed_cfts = cfts;
- goto err;
- }
- }
-
- css->flags |= CSS_VISIBLE;
-
- return 0;
-err:
- list_for_each_entry(cfts, &css->ss->cfts, node) {
- if (cfts == failed_cfts)
- break;
- cgroup_addrm_files(css, cgrp, cfts, false);
- }
- return ret;
-}
-
-static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
-{
- struct cgroup *dcgrp = &dst_root->cgrp;
- struct cgroup_subsys *ss;
- int ssid, i, ret;
-
- lockdep_assert_held(&cgroup_mutex);
-
- do_each_subsys_mask(ss, ssid, ss_mask) {
- /*
- * If @ss has non-root csses attached to it, can't move.
- * If @ss is an implicit controller, it is exempt from this
- * rule and can be stolen.
- */
- if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) &&
- !ss->implicit_on_dfl)
- return -EBUSY;
-
- /* can't move between two non-dummy roots either */
- if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
- return -EBUSY;
- } while_each_subsys_mask();
-
- do_each_subsys_mask(ss, ssid, ss_mask) {
- struct cgroup_root *src_root = ss->root;
- struct cgroup *scgrp = &src_root->cgrp;
- struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
- struct css_set *cset;
-
- WARN_ON(!css || cgroup_css(dcgrp, ss));
-
- /* disable from the source */
- src_root->subsys_mask &= ~(1 << ssid);
- WARN_ON(cgroup_apply_control(scgrp));
- cgroup_finalize_control(scgrp, 0);
-
- /* rebind */
- RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
- rcu_assign_pointer(dcgrp->subsys[ssid], css);
- ss->root = dst_root;
- css->cgroup = dcgrp;
-
- spin_lock_irq(&css_set_lock);
- hash_for_each(css_set_table, i, cset, hlist)
- list_move_tail(&cset->e_cset_node[ss->id],
- &dcgrp->e_csets[ss->id]);
- spin_unlock_irq(&css_set_lock);
-
- /* default hierarchy doesn't enable controllers by default */
- dst_root->subsys_mask |= 1 << ssid;
- if (dst_root == &cgrp_dfl_root) {
- static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
- } else {
- dcgrp->subtree_control |= 1 << ssid;
- static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
- }
-
- ret = cgroup_apply_control(dcgrp);
- if (ret)
- pr_warn("partial failure to rebind %s controller (err=%d)\n",
- ss->name, ret);
-
- if (ss->bind)
- ss->bind(css);
- } while_each_subsys_mask();
-
- kernfs_activate(dcgrp->kn);
- return 0;
-}
-
-static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
- struct kernfs_root *kf_root)
-{
- int len = 0;
- char *buf = NULL;
- struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
- struct cgroup *ns_cgroup;
-
- buf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
-
- spin_lock_irq(&css_set_lock);
- ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot);
- len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX);
- spin_unlock_irq(&css_set_lock);
-
- if (len >= PATH_MAX)
- len = -ERANGE;
- else if (len > 0) {
- seq_escape(sf, buf, " \t\n\\");
- len = 0;
- }
- kfree(buf);
- return len;
-}
-
-static int cgroup_show_options(struct seq_file *seq,
- struct kernfs_root *kf_root)
-{
- struct cgroup_root *root = cgroup_root_from_kf(kf_root);
- struct cgroup_subsys *ss;
- int ssid;
-
- if (root != &cgrp_dfl_root)
- for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
- seq_show_option(seq, ss->legacy_name, NULL);
- if (root->flags & CGRP_ROOT_NOPREFIX)
- seq_puts(seq, ",noprefix");
- if (root->flags & CGRP_ROOT_XATTR)
- seq_puts(seq, ",xattr");
-
- spin_lock(&release_agent_path_lock);
- if (strlen(root->release_agent_path))
- seq_show_option(seq, "release_agent",
- root->release_agent_path);
- spin_unlock(&release_agent_path_lock);
-
- if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
- seq_puts(seq, ",clone_children");
- if (strlen(root->name))
- seq_show_option(seq, "name", root->name);
- return 0;
-}
-
-struct cgroup_sb_opts {
- u16 subsys_mask;
- unsigned int flags;
- char *release_agent;
- bool cpuset_clone_children;
- char *name;
- /* User explicitly requested empty subsystem */
- bool none;
-};
-
-static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
-{
- char *token, *o = data;
- bool all_ss = false, one_ss = false;
- u16 mask = U16_MAX;
- struct cgroup_subsys *ss;
- int nr_opts = 0;
- int i;
-
-#ifdef CONFIG_CPUSETS
- mask = ~((u16)1 << cpuset_cgrp_id);
-#endif
-
- memset(opts, 0, sizeof(*opts));
-
- while ((token = strsep(&o, ",")) != NULL) {
- nr_opts++;
-
- if (!*token)
- return -EINVAL;
- if (!strcmp(token, "none")) {
- /* Explicitly have no subsystems */
- opts->none = true;
- continue;
- }
- if (!strcmp(token, "all")) {
- /* Mutually exclusive option 'all' + subsystem name */
- if (one_ss)
- return -EINVAL;
- all_ss = true;
- continue;
- }
- if (!strcmp(token, "noprefix")) {
- opts->flags |= CGRP_ROOT_NOPREFIX;
- continue;
- }
- if (!strcmp(token, "clone_children")) {
- opts->cpuset_clone_children = true;
- continue;
- }
- if (!strcmp(token, "xattr")) {
- opts->flags |= CGRP_ROOT_XATTR;
- continue;
- }
- if (!strncmp(token, "release_agent=", 14)) {
- /* Specifying two release agents is forbidden */
- if (opts->release_agent)
- return -EINVAL;
- opts->release_agent =
- kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
- if (!opts->release_agent)
- return -ENOMEM;
- continue;
- }
- if (!strncmp(token, "name=", 5)) {
- const char *name = token + 5;
- /* Can't specify an empty name */
- if (!strlen(name))
- return -EINVAL;
- /* Must match [\w.-]+ */
- for (i = 0; i < strlen(name); i++) {
- char c = name[i];
- if (isalnum(c))
- continue;
- if ((c == '.') || (c == '-') || (c == '_'))
- continue;
- return -EINVAL;
- }
- /* Specifying two names is forbidden */
- if (opts->name)
- return -EINVAL;
- opts->name = kstrndup(name,
- MAX_CGROUP_ROOT_NAMELEN - 1,
- GFP_KERNEL);
- if (!opts->name)
- return -ENOMEM;
-
- continue;
- }
-
- for_each_subsys(ss, i) {
- if (strcmp(token, ss->legacy_name))
- continue;
- if (!cgroup_ssid_enabled(i))
- continue;
- if (cgroup_ssid_no_v1(i))
- continue;
-
- /* Mutually exclusive option 'all' + subsystem name */
- if (all_ss)
- return -EINVAL;
- opts->subsys_mask |= (1 << i);
- one_ss = true;
-
- break;
- }
- if (i == CGROUP_SUBSYS_COUNT)
- return -ENOENT;
- }
-
- /*
- * If the 'all' option was specified select all the subsystems,
- * otherwise if 'none', 'name=' and a subsystem name options were
- * not specified, let's default to 'all'
- */
- if (all_ss || (!one_ss && !opts->none && !opts->name))
- for_each_subsys(ss, i)
- if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
- opts->subsys_mask |= (1 << i);
-
- /*
- * We either have to specify by name or by subsystems. (So all
- * empty hierarchies must have a name).
- */
- if (!opts->subsys_mask && !opts->name)
- return -EINVAL;
-
- /*
- * Option noprefix was introduced just for backward compatibility
- * with the old cpuset, so we allow noprefix only if mounting just
- * the cpuset subsystem.
- */
- if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
- return -EINVAL;
-
- /* Can't specify "none" and some subsystems */
- if (opts->subsys_mask && opts->none)
- return -EINVAL;
-
- return 0;
-}
-
-static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
-{
- int ret = 0;
- struct cgroup_root *root = cgroup_root_from_kf(kf_root);
- struct cgroup_sb_opts opts;
- u16 added_mask, removed_mask;
-
- if (root == &cgrp_dfl_root) {
- pr_err("remount is not allowed\n");
- return -EINVAL;
- }
-
- cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
- /* See what subsystems are wanted */
- ret = parse_cgroupfs_options(data, &opts);
- if (ret)
- goto out_unlock;
-
- if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
- pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
- task_tgid_nr(current), current->comm);
-
- added_mask = opts.subsys_mask & ~root->subsys_mask;
- removed_mask = root->subsys_mask & ~opts.subsys_mask;
-
- /* Don't allow flags or name to change at remount */
- if ((opts.flags ^ root->flags) ||
- (opts.name && strcmp(opts.name, root->name))) {
- pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
- opts.flags, opts.name ?: "", root->flags, root->name);
- ret = -EINVAL;
- goto out_unlock;
- }
-
- /* remounting is not allowed for populated hierarchies */
- if (!list_empty(&root->cgrp.self.children)) {
- ret = -EBUSY;
- goto out_unlock;
- }
-
- ret = rebind_subsystems(root, added_mask);
- if (ret)
- goto out_unlock;
-
- WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
-
- if (opts.release_agent) {
- spin_lock(&release_agent_path_lock);
- strcpy(root->release_agent_path, opts.release_agent);
- spin_unlock(&release_agent_path_lock);
- }
-
- trace_cgroup_remount(root);
-
- out_unlock:
- kfree(opts.release_agent);
- kfree(opts.name);
- mutex_unlock(&cgroup_mutex);
- return ret;
-}
-
-/*
- * To reduce the fork() overhead for systems that are not actually using
- * their cgroups capability, we don't maintain the lists running through
- * each css_set to its tasks until we see the list actually used - in other
- * words after the first mount.
- */
-static bool use_task_css_set_links __read_mostly;
-
-static void cgroup_enable_task_cg_lists(void)
-{
- struct task_struct *p, *g;
-
- spin_lock_irq(&css_set_lock);
-
- if (use_task_css_set_links)
- goto out_unlock;
-
- use_task_css_set_links = true;
-
- /*
- * We need tasklist_lock because RCU is not safe against
- * while_each_thread(). Besides, a forking task that has passed
- * cgroup_post_fork() without seeing use_task_css_set_links = 1
- * is not guaranteed to have its child immediately visible in the
- * tasklist if we walk through it with RCU.
- */
- read_lock(&tasklist_lock);
- do_each_thread(g, p) {
- WARN_ON_ONCE(!list_empty(&p->cg_list) ||
- task_css_set(p) != &init_css_set);
-
- /*
- * We should check if the process is exiting, otherwise
- * it will race with cgroup_exit() in that the list
- * entry won't be deleted though the process has exited.
- * Do it while holding siglock so that we don't end up
- * racing against cgroup_exit().
- *
- * Interrupts were already disabled while acquiring
- * the css_set_lock, so we do not need to disable it
- * again when acquiring the sighand->siglock here.
- */
- spin_lock(&p->sighand->siglock);
- if (!(p->flags & PF_EXITING)) {
- struct css_set *cset = task_css_set(p);
-
- if (!css_set_populated(cset))
- css_set_update_populated(cset, true);
- list_add_tail(&p->cg_list, &cset->tasks);
- get_css_set(cset);
- }
- spin_unlock(&p->sighand->siglock);
- } while_each_thread(g, p);
- read_unlock(&tasklist_lock);
-out_unlock:
- spin_unlock_irq(&css_set_lock);
-}
-
-static void init_cgroup_housekeeping(struct cgroup *cgrp)
-{
- struct cgroup_subsys *ss;
- int ssid;
-
- INIT_LIST_HEAD(&cgrp->self.sibling);
- INIT_LIST_HEAD(&cgrp->self.children);
- INIT_LIST_HEAD(&cgrp->cset_links);
- INIT_LIST_HEAD(&cgrp->pidlists);
- mutex_init(&cgrp->pidlist_mutex);
- cgrp->self.cgroup = cgrp;
- cgrp->self.flags |= CSS_ONLINE;
-
- for_each_subsys(ss, ssid)
- INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
-
- init_waitqueue_head(&cgrp->offline_waitq);
- INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
-}
-
-static void init_cgroup_root(struct cgroup_root *root,
- struct cgroup_sb_opts *opts)
-{
- struct cgroup *cgrp = &root->cgrp;
-
- INIT_LIST_HEAD(&root->root_list);
- atomic_set(&root->nr_cgrps, 1);
- cgrp->root = root;
- init_cgroup_housekeeping(cgrp);
- idr_init(&root->cgroup_idr);
-
- root->flags = opts->flags;
- if (opts->release_agent)
- strcpy(root->release_agent_path, opts->release_agent);
- if (opts->name)
- strcpy(root->name, opts->name);
- if (opts->cpuset_clone_children)
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
-}
-
-static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
-{
- LIST_HEAD(tmp_links);
- struct cgroup *root_cgrp = &root->cgrp;
- struct css_set *cset;
- int i, ret;
-
- lockdep_assert_held(&cgroup_mutex);
-
- ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL);
- if (ret < 0)
- goto out;
- root_cgrp->id = ret;
- root_cgrp->ancestor_ids[0] = ret;
-
- ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0,
- GFP_KERNEL);
- if (ret)
- goto out;
-
- /*
- * We're accessing css_set_count without locking css_set_lock here,
- * but that's OK - it can only be increased by someone holding
- * cgroup_lock, and that's us. Later rebinding may disable
- * controllers on the default hierarchy and thus create new csets,
- * which can't be more than the existing ones. Allocate 2x.
- */
- ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links);
- if (ret)
- goto cancel_ref;
-
- ret = cgroup_init_root_id(root);
- if (ret)
- goto cancel_ref;
-
- root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
- KERNFS_ROOT_CREATE_DEACTIVATED,
- root_cgrp);
- if (IS_ERR(root->kf_root)) {
- ret = PTR_ERR(root->kf_root);
- goto exit_root_id;
- }
- root_cgrp->kn = root->kf_root->kn;
-
- ret = css_populate_dir(&root_cgrp->self);
- if (ret)
- goto destroy_root;
-
- ret = rebind_subsystems(root, ss_mask);
- if (ret)
- goto destroy_root;
-
- trace_cgroup_setup_root(root);
-
- /*
- * There must be no failure case after here, since rebinding takes
- * care of subsystems' refcounts, which are explicitly dropped in
- * the failure exit path.
- */
- list_add(&root->root_list, &cgroup_roots);
- cgroup_root_count++;
-
- /*
- * Link the root cgroup in this hierarchy into all the css_set
- * objects.
- */
- spin_lock_irq(&css_set_lock);
- hash_for_each(css_set_table, i, cset, hlist) {
- link_css_set(&tmp_links, cset, root_cgrp);
- if (css_set_populated(cset))
- cgroup_update_populated(root_cgrp, true);
- }
- spin_unlock_irq(&css_set_lock);
-
- BUG_ON(!list_empty(&root_cgrp->self.children));
- BUG_ON(atomic_read(&root->nr_cgrps) != 1);
-
- kernfs_activate(root_cgrp->kn);
- ret = 0;
- goto out;
-
-destroy_root:
- kernfs_destroy_root(root->kf_root);
- root->kf_root = NULL;
-exit_root_id:
- cgroup_exit_root_id(root);
-cancel_ref:
- percpu_ref_exit(&root_cgrp->self.refcnt);
-out:
- free_cgrp_cset_links(&tmp_links);
- return ret;
-}
-
-static struct dentry *cgroup_mount(struct file_system_type *fs_type,
- int flags, const char *unused_dev_name,
- void *data)
-{
- bool is_v2 = fs_type == &cgroup2_fs_type;
- struct super_block *pinned_sb = NULL;
- struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
- struct cgroup_subsys *ss;
- struct cgroup_root *root;
- struct cgroup_sb_opts opts;
- struct dentry *dentry;
- int ret;
- int i;
- bool new_sb;
-
- get_cgroup_ns(ns);
-
- /* Check if the caller has permission to mount. */
- if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
- put_cgroup_ns(ns);
- return ERR_PTR(-EPERM);
- }
-
- /*
- * The first time anyone tries to mount a cgroup, enable the list
- * linking each css_set to its tasks and fix up all existing tasks.
- */
- if (!use_task_css_set_links)
- cgroup_enable_task_cg_lists();
-
- if (is_v2) {
- if (data) {
- pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
- put_cgroup_ns(ns);
- return ERR_PTR(-EINVAL);
- }
- cgrp_dfl_visible = true;
- root = &cgrp_dfl_root;
- cgroup_get(&root->cgrp);
- goto out_mount;
- }
-
- cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
-
- /* First find the desired set of subsystems */
- ret = parse_cgroupfs_options(data, &opts);
- if (ret)
- goto out_unlock;
-
- /*
- * Destruction of cgroup root is asynchronous, so subsystems may
- * still be dying after the previous unmount. Let's drain the
- * dying subsystems. We just need to ensure that the ones
- * unmounted previously finish dying and don't care about new ones
- * starting. Testing ref liveliness is good enough.
- */
- for_each_subsys(ss, i) {
- if (!(opts.subsys_mask & (1 << i)) ||
- ss->root == &cgrp_dfl_root)
- continue;
-
- if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
- mutex_unlock(&cgroup_mutex);
- msleep(10);
- ret = restart_syscall();
- goto out_free;
- }
- cgroup_put(&ss->root->cgrp);
- }
-
- for_each_root(root) {
- bool name_match = false;
-
- if (root == &cgrp_dfl_root)
- continue;
-
- /*
- * If we asked for a name then it must match. Also, if
- * name matches but sybsys_mask doesn't, we should fail.
- * Remember whether name matched.
- */
- if (opts.name) {
- if (strcmp(opts.name, root->name))
- continue;
- name_match = true;
- }
-
- /*
- * If we asked for subsystems (or explicitly for no
- * subsystems) then they must match.
- */
- if ((opts.subsys_mask || opts.none) &&
- (opts.subsys_mask != root->subsys_mask)) {
- if (!name_match)
- continue;
- ret = -EBUSY;
- goto out_unlock;
- }
-
- if (root->flags ^ opts.flags)
- pr_warn("new mount options do not match the existing superblock, will be ignored\n");
-
- /*
- * We want to reuse @root whose lifetime is governed by its
- * ->cgrp. Let's check whether @root is alive and keep it
- * that way. As cgroup_kill_sb() can happen anytime, we
- * want to block it by pinning the sb so that @root doesn't
- * get killed before mount is complete.
- *
- * With the sb pinned, tryget_live can reliably indicate
- * whether @root can be reused. If it's being killed,
- * drain it. We can use wait_queue for the wait but this
- * path is super cold. Let's just sleep a bit and retry.
- */
- pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
- if (IS_ERR(pinned_sb) ||
- !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
- mutex_unlock(&cgroup_mutex);
- if (!IS_ERR_OR_NULL(pinned_sb))
- deactivate_super(pinned_sb);
- msleep(10);
- ret = restart_syscall();
- goto out_free;
- }
-
- ret = 0;
- goto out_unlock;
- }
-
- /*
- * No such thing, create a new one. name= matching without subsys
- * specification is allowed for already existing hierarchies but we
- * can't create new one without subsys specification.
- */
- if (!opts.subsys_mask && !opts.none) {
- ret = -EINVAL;
- goto out_unlock;
- }
-
- /* Hierarchies may only be created in the initial cgroup namespace. */
- if (ns != &init_cgroup_ns) {
- ret = -EPERM;
- goto out_unlock;
- }
-
- root = kzalloc(sizeof(*root), GFP_KERNEL);
- if (!root) {
- ret = -ENOMEM;
- goto out_unlock;
- }
-
- init_cgroup_root(root, &opts);
-
- ret = cgroup_setup_root(root, opts.subsys_mask);
- if (ret)
- cgroup_free_root(root);
-
-out_unlock:
- mutex_unlock(&cgroup_mutex);
-out_free:
- kfree(opts.release_agent);
- kfree(opts.name);
-
- if (ret) {
- put_cgroup_ns(ns);
- return ERR_PTR(ret);
- }
-out_mount:
- dentry = kernfs_mount(fs_type, flags, root->kf_root,
- is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
- &new_sb);
-
- /*
- * In non-init cgroup namespace, instead of root cgroup's
- * dentry, we return the dentry corresponding to the
- * cgroupns->root_cgrp.
- */
- if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
- struct dentry *nsdentry;
- struct cgroup *cgrp;
-
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
-
- cgrp = cset_cgroup_from_root(ns->root_cset, root);
-
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
-
- nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
- dput(dentry);
- dentry = nsdentry;
- }
-
- if (IS_ERR(dentry) || !new_sb)
- cgroup_put(&root->cgrp);
-
- /*
- * If @pinned_sb, we're reusing an existing root and holding an
- * extra ref on its sb. Mount is complete. Put the extra ref.
- */
- if (pinned_sb) {
- WARN_ON(new_sb);
- deactivate_super(pinned_sb);
- }
-
- put_cgroup_ns(ns);
- return dentry;
-}
-
-static void cgroup_kill_sb(struct super_block *sb)
-{
- struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
- struct cgroup_root *root = cgroup_root_from_kf(kf_root);
-
- /*
- * If @root doesn't have any mounts or children, start killing it.
- * This prevents new mounts by disabling percpu_ref_tryget_live().
- * cgroup_mount() may wait for @root's release.
- *
- * And don't kill the default root.
- */
- if (!list_empty(&root->cgrp.self.children) ||
- root == &cgrp_dfl_root)
- cgroup_put(&root->cgrp);
- else
- percpu_ref_kill(&root->cgrp.self.refcnt);
-
- kernfs_kill_sb(sb);
-}
-
-static struct file_system_type cgroup_fs_type = {
- .name = "cgroup",
- .mount = cgroup_mount,
- .kill_sb = cgroup_kill_sb,
- .fs_flags = FS_USERNS_MOUNT,
-};
-
-static struct file_system_type cgroup2_fs_type = {
- .name = "cgroup2",
- .mount = cgroup_mount,
- .kill_sb = cgroup_kill_sb,
- .fs_flags = FS_USERNS_MOUNT,
-};
-
-static int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
- struct cgroup_namespace *ns)
-{
- struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
-
- return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
-}
-
-int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
- struct cgroup_namespace *ns)
-{
- int ret;
-
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
-
- ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns);
-
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
-
- return ret;
-}
-EXPORT_SYMBOL_GPL(cgroup_path_ns);
-
-/**
- * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
- * @task: target task
- * @buf: the buffer to write the path into
- * @buflen: the length of the buffer
- *
- * Determine @task's cgroup on the first (the one with the lowest non-zero
- * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
- * function grabs cgroup_mutex and shouldn't be used inside locks used by
- * cgroup controller callbacks.
- *
- * Return value is the same as kernfs_path().
- */
-int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
-{
- struct cgroup_root *root;
- struct cgroup *cgrp;
- int hierarchy_id = 1;
- int ret;
-
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
-
- root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
-
- if (root) {
- cgrp = task_cgroup_from_root(task, root);
- ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
- } else {
- /* if no hierarchy exists, everyone is in "/" */
- ret = strlcpy(buf, "/", buflen);
- }
-
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
- return ret;
-}
-EXPORT_SYMBOL_GPL(task_cgroup_path);
-
-/* used to track tasks and other necessary states during migration */
-struct cgroup_taskset {
- /* the src and dst cset list running through cset->mg_node */
- struct list_head src_csets;
- struct list_head dst_csets;
-
- /* the subsys currently being processed */
- int ssid;
-
- /*
- * Fields for cgroup_taskset_*() iteration.
- *
- * Before migration is committed, the target migration tasks are on
- * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
- * the csets on ->dst_csets. ->csets point to either ->src_csets
- * or ->dst_csets depending on whether migration is committed.
- *
- * ->cur_csets and ->cur_task point to the current task position
- * during iteration.
- */
- struct list_head *csets;
- struct css_set *cur_cset;
- struct task_struct *cur_task;
-};
-
-#define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \
- .src_csets = LIST_HEAD_INIT(tset.src_csets), \
- .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
- .csets = &tset.src_csets, \
-}
-
-/**
- * cgroup_taskset_add - try to add a migration target task to a taskset
- * @task: target task
- * @tset: target taskset
- *
- * Add @task, which is a migration target, to @tset. This function becomes
- * noop if @task doesn't need to be migrated. @task's css_set should have
- * been added as a migration source and @task->cg_list will be moved from
- * the css_set's tasks list to mg_tasks one.
- */
-static void cgroup_taskset_add(struct task_struct *task,
- struct cgroup_taskset *tset)
-{
- struct css_set *cset;
-
- lockdep_assert_held(&css_set_lock);
-
- /* @task either already exited or can't exit until the end */
- if (task->flags & PF_EXITING)
- return;
-
- /* leave @task alone if post_fork() hasn't linked it yet */
- if (list_empty(&task->cg_list))
- return;
-
- cset = task_css_set(task);
- if (!cset->mg_src_cgrp)
- return;
-
- list_move_tail(&task->cg_list, &cset->mg_tasks);
- if (list_empty(&cset->mg_node))
- list_add_tail(&cset->mg_node, &tset->src_csets);
- if (list_empty(&cset->mg_dst_cset->mg_node))
- list_move_tail(&cset->mg_dst_cset->mg_node,
- &tset->dst_csets);
-}
-
-/**
- * cgroup_taskset_first - reset taskset and return the first task
- * @tset: taskset of interest
- * @dst_cssp: output variable for the destination css
- *
- * @tset iteration is initialized and the first task is returned.
- */
-struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
- struct cgroup_subsys_state **dst_cssp)
-{
- tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
- tset->cur_task = NULL;
-
- return cgroup_taskset_next(tset, dst_cssp);
-}
-
-/**
- * cgroup_taskset_next - iterate to the next task in taskset
- * @tset: taskset of interest
- * @dst_cssp: output variable for the destination css
- *
- * Return the next task in @tset. Iteration must have been initialized
- * with cgroup_taskset_first().
- */
-struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
- struct cgroup_subsys_state **dst_cssp)
-{
- struct css_set *cset = tset->cur_cset;
- struct task_struct *task = tset->cur_task;
-
- while (&cset->mg_node != tset->csets) {
- if (!task)
- task = list_first_entry(&cset->mg_tasks,
- struct task_struct, cg_list);
- else
- task = list_next_entry(task, cg_list);
-
- if (&task->cg_list != &cset->mg_tasks) {
- tset->cur_cset = cset;
- tset->cur_task = task;
-
- /*
- * This function may be called both before and
- * after cgroup_taskset_migrate(). The two cases
- * can be distinguished by looking at whether @cset
- * has its ->mg_dst_cset set.
- */
- if (cset->mg_dst_cset)
- *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
- else
- *dst_cssp = cset->subsys[tset->ssid];
-
- return task;
- }
-
- cset = list_next_entry(cset, mg_node);
- task = NULL;
- }
-
- return NULL;
-}
-
-/**
- * cgroup_taskset_migrate - migrate a taskset
- * @tset: taget taskset
- * @root: cgroup root the migration is taking place on
- *
- * Migrate tasks in @tset as setup by migration preparation functions.
- * This function fails iff one of the ->can_attach callbacks fails and
- * guarantees that either all or none of the tasks in @tset are migrated.
- * @tset is consumed regardless of success.
- */
-static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
- struct cgroup_root *root)
-{
- struct cgroup_subsys *ss;
- struct task_struct *task, *tmp_task;
- struct css_set *cset, *tmp_cset;
- int ssid, failed_ssid, ret;
-
- /* methods shouldn't be called if no task is actually migrating */
- if (list_empty(&tset->src_csets))
- return 0;
-
- /* check that we can legitimately attach to the cgroup */
- do_each_subsys_mask(ss, ssid, root->subsys_mask) {
- if (ss->can_attach) {
- tset->ssid = ssid;
- ret = ss->can_attach(tset);
- if (ret) {
- failed_ssid = ssid;
- goto out_cancel_attach;
- }
- }
- } while_each_subsys_mask();
-
- /*
- * Now that we're guaranteed success, proceed to move all tasks to
- * the new cgroup. There are no failure cases after here, so this
- * is the commit point.
- */
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(cset, &tset->src_csets, mg_node) {
- list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) {
- struct css_set *from_cset = task_css_set(task);
- struct css_set *to_cset = cset->mg_dst_cset;
-
- get_css_set(to_cset);
- css_set_move_task(task, from_cset, to_cset, true);
- put_css_set_locked(from_cset);
- }
- }
- spin_unlock_irq(&css_set_lock);
-
- /*
- * Migration is committed, all target tasks are now on dst_csets.
- * Nothing is sensitive to fork() after this point. Notify
- * controllers that migration is complete.
- */
- tset->csets = &tset->dst_csets;
-
- do_each_subsys_mask(ss, ssid, root->subsys_mask) {
- if (ss->attach) {
- tset->ssid = ssid;
- ss->attach(tset);
- }
- } while_each_subsys_mask();
-
- ret = 0;
- goto out_release_tset;
-
-out_cancel_attach:
- do_each_subsys_mask(ss, ssid, root->subsys_mask) {
- if (ssid == failed_ssid)
- break;
- if (ss->cancel_attach) {
- tset->ssid = ssid;
- ss->cancel_attach(tset);
- }
- } while_each_subsys_mask();
-out_release_tset:
- spin_lock_irq(&css_set_lock);
- list_splice_init(&tset->dst_csets, &tset->src_csets);
- list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) {
- list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
- list_del_init(&cset->mg_node);
- }
- spin_unlock_irq(&css_set_lock);
- return ret;
-}
-
-/**
- * cgroup_may_migrate_to - verify whether a cgroup can be migration destination
- * @dst_cgrp: destination cgroup to test
- *
- * On the default hierarchy, except for the root, subtree_control must be
- * zero for migration destination cgroups with tasks so that child cgroups
- * don't compete against tasks.
- */
-static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
-{
- return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) ||
- !dst_cgrp->subtree_control;
-}
-
-/**
- * cgroup_migrate_finish - cleanup after attach
- * @preloaded_csets: list of preloaded css_sets
- *
- * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
- * those functions for details.
- */
-static void cgroup_migrate_finish(struct list_head *preloaded_csets)
-{
- struct css_set *cset, *tmp_cset;
-
- lockdep_assert_held(&cgroup_mutex);
-
- spin_lock_irq(&css_set_lock);
- list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
- cset->mg_src_cgrp = NULL;
- cset->mg_dst_cgrp = NULL;
- cset->mg_dst_cset = NULL;
- list_del_init(&cset->mg_preload_node);
- put_css_set_locked(cset);
- }
- spin_unlock_irq(&css_set_lock);
-}
-
-/**
- * cgroup_migrate_add_src - add a migration source css_set
- * @src_cset: the source css_set to add
- * @dst_cgrp: the destination cgroup
- * @preloaded_csets: list of preloaded css_sets
- *
- * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
- * @src_cset and add it to @preloaded_csets, which should later be cleaned
- * up by cgroup_migrate_finish().
- *
- * This function may be called without holding cgroup_threadgroup_rwsem
- * even if the target is a process. Threads may be created and destroyed
- * but as long as cgroup_mutex is not dropped, no new css_set can be put
- * into play and the preloaded css_sets are guaranteed to cover all
- * migrations.
- */
-static void cgroup_migrate_add_src(struct css_set *src_cset,
- struct cgroup *dst_cgrp,
- struct list_head *preloaded_csets)
-{
- struct cgroup *src_cgrp;
-
- lockdep_assert_held(&cgroup_mutex);
- lockdep_assert_held(&css_set_lock);
-
- /*
- * If ->dead, @src_set is associated with one or more dead cgroups
- * and doesn't contain any migratable tasks. Ignore it early so
- * that the rest of migration path doesn't get confused by it.
- */
- if (src_cset->dead)
- return;
-
- src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
-
- if (!list_empty(&src_cset->mg_preload_node))
- return;
-
- WARN_ON(src_cset->mg_src_cgrp);
- WARN_ON(src_cset->mg_dst_cgrp);
- WARN_ON(!list_empty(&src_cset->mg_tasks));
- WARN_ON(!list_empty(&src_cset->mg_node));
-
- src_cset->mg_src_cgrp = src_cgrp;
- src_cset->mg_dst_cgrp = dst_cgrp;
- get_css_set(src_cset);
- list_add(&src_cset->mg_preload_node, preloaded_csets);
-}
-
-/**
- * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
- * @preloaded_csets: list of preloaded source css_sets
- *
- * Tasks are about to be moved and all the source css_sets have been
- * preloaded to @preloaded_csets. This function looks up and pins all
- * destination css_sets, links each to its source, and append them to
- * @preloaded_csets.
- *
- * This function must be called after cgroup_migrate_add_src() has been
- * called on each migration source css_set. After migration is performed
- * using cgroup_migrate(), cgroup_migrate_finish() must be called on
- * @preloaded_csets.
- */
-static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
-{
- LIST_HEAD(csets);
- struct css_set *src_cset, *tmp_cset;
-
- lockdep_assert_held(&cgroup_mutex);
-
- /* look up the dst cset for each src cset and link it to src */
- list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) {
- struct css_set *dst_cset;
-
- dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp);
- if (!dst_cset)
- goto err;
-
- WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
-
- /*
- * If src cset equals dst, it's noop. Drop the src.
- * cgroup_migrate() will skip the cset too. Note that we
- * can't handle src == dst as some nodes are used by both.
- */
- if (src_cset == dst_cset) {
- src_cset->mg_src_cgrp = NULL;
- src_cset->mg_dst_cgrp = NULL;
- list_del_init(&src_cset->mg_preload_node);
- put_css_set(src_cset);
- put_css_set(dst_cset);
- continue;
- }
-
- src_cset->mg_dst_cset = dst_cset;
-
- if (list_empty(&dst_cset->mg_preload_node))
- list_add(&dst_cset->mg_preload_node, &csets);
- else
- put_css_set(dst_cset);
- }
-
- list_splice_tail(&csets, preloaded_csets);
- return 0;
-err:
- cgroup_migrate_finish(&csets);
- return -ENOMEM;
-}
-
-/**
- * cgroup_migrate - migrate a process or task to a cgroup
- * @leader: the leader of the process or the task to migrate
- * @threadgroup: whether @leader points to the whole process or a single task
- * @root: cgroup root migration is taking place on
- *
- * Migrate a process or task denoted by @leader. If migrating a process,
- * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
- * responsible for invoking cgroup_migrate_add_src() and
- * cgroup_migrate_prepare_dst() on the targets before invoking this
- * function and following up with cgroup_migrate_finish().
- *
- * As long as a controller's ->can_attach() doesn't fail, this function is
- * guaranteed to succeed. This means that, excluding ->can_attach()
- * failure, when migrating multiple targets, the success or failure can be
- * decided for all targets by invoking group_migrate_prepare_dst() before
- * actually starting migrating.
- */
-static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
- struct cgroup_root *root)
-{
- struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
- struct task_struct *task;
-
- /*
- * Prevent freeing of tasks while we take a snapshot. Tasks that are
- * already PF_EXITING could be freed from underneath us unless we
- * take an rcu_read_lock.
- */
- spin_lock_irq(&css_set_lock);
- rcu_read_lock();
- task = leader;
- do {
- cgroup_taskset_add(task, &tset);
- if (!threadgroup)
- break;
- } while_each_thread(leader, task);
- rcu_read_unlock();
- spin_unlock_irq(&css_set_lock);
-
- return cgroup_taskset_migrate(&tset, root);
-}
-
-/**
- * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
- * @dst_cgrp: the cgroup to attach to
- * @leader: the task or the leader of the threadgroup to be attached
- * @threadgroup: attach the whole threadgroup?
- *
- * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
- */
-static int cgroup_attach_task(struct cgroup *dst_cgrp,
- struct task_struct *leader, bool threadgroup)
-{
- LIST_HEAD(preloaded_csets);
- struct task_struct *task;
- int ret;
-
- if (!cgroup_may_migrate_to(dst_cgrp))
- return -EBUSY;
-
- /* look up all src csets */
- spin_lock_irq(&css_set_lock);
- rcu_read_lock();
- task = leader;
- do {
- cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
- &preloaded_csets);
- if (!threadgroup)
- break;
- } while_each_thread(leader, task);
- rcu_read_unlock();
- spin_unlock_irq(&css_set_lock);
-
- /* prepare dst csets and commit */
- ret = cgroup_migrate_prepare_dst(&preloaded_csets);
- if (!ret)
- ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root);
-
- cgroup_migrate_finish(&preloaded_csets);
-
- if (!ret)
- trace_cgroup_attach_task(dst_cgrp, leader, threadgroup);
-
- return ret;
-}
-
-static int cgroup_procs_write_permission(struct task_struct *task,
- struct cgroup *dst_cgrp,
- struct kernfs_open_file *of)
-{
- const struct cred *cred = current_cred();
- const struct cred *tcred = get_task_cred(task);
- int ret = 0;
-
- /*
- * even if we're attaching all tasks in the thread group, we only
- * need to check permissions on one of them.
- */
- if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
- !uid_eq(cred->euid, tcred->uid) &&
- !uid_eq(cred->euid, tcred->suid))
- ret = -EACCES;
-
- if (!ret && cgroup_on_dfl(dst_cgrp)) {
- struct super_block *sb = of->file->f_path.dentry->d_sb;
- struct cgroup *cgrp;
- struct inode *inode;
-
- spin_lock_irq(&css_set_lock);
- cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
- spin_unlock_irq(&css_set_lock);
-
- while (!cgroup_is_descendant(dst_cgrp, cgrp))
- cgrp = cgroup_parent(cgrp);
-
- ret = -ENOMEM;
- inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
- if (inode) {
- ret = inode_permission(inode, MAY_WRITE);
- iput(inode);
- }
- }
-
- put_cred(tcred);
- return ret;
-}
-
-/*
- * Find the task_struct of the task to attach by vpid and pass it along to the
- * function to attach either it or all tasks in its threadgroup. Will lock
- * cgroup_mutex and threadgroup.
- */
-static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off, bool threadgroup)
-{
- struct task_struct *tsk;
- struct cgroup_subsys *ss;
- struct cgroup *cgrp;
- pid_t pid;
- int ssid, ret;
-
- if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
- return -EINVAL;
-
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENODEV;
-
- percpu_down_write(&cgroup_threadgroup_rwsem);
- rcu_read_lock();
- if (pid) {
- tsk = find_task_by_vpid(pid);
- if (!tsk) {
- ret = -ESRCH;
- goto out_unlock_rcu;
- }
- } else {
- tsk = current;
- }
-
- if (threadgroup)
- tsk = tsk->group_leader;
-
- /*
- * Workqueue threads may acquire PF_NO_SETAFFINITY and become
- * trapped in a cpuset, or RT worker may be born in a cgroup
- * with no rt_runtime allocated. Just say no.
- */
- if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
- ret = -EINVAL;
- goto out_unlock_rcu;
- }
-
- get_task_struct(tsk);
- rcu_read_unlock();
-
- ret = cgroup_procs_write_permission(tsk, cgrp, of);
- if (!ret)
- ret = cgroup_attach_task(cgrp, tsk, threadgroup);
-
- put_task_struct(tsk);
- goto out_unlock_threadgroup;
-
-out_unlock_rcu:
- rcu_read_unlock();
-out_unlock_threadgroup:
- percpu_up_write(&cgroup_threadgroup_rwsem);
- for_each_subsys(ss, ssid)
- if (ss->post_attach)
- ss->post_attach();
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
-}
-
-/**
- * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
- * @from: attach to all cgroups of a given task
- * @tsk: the task to be attached
- */
-int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
-{
- struct cgroup_root *root;
- int retval = 0;
-
- mutex_lock(&cgroup_mutex);
- percpu_down_write(&cgroup_threadgroup_rwsem);
- for_each_root(root) {
- struct cgroup *from_cgrp;
-
- if (root == &cgrp_dfl_root)
- continue;
-
- spin_lock_irq(&css_set_lock);
- from_cgrp = task_cgroup_from_root(from, root);
- spin_unlock_irq(&css_set_lock);
-
- retval = cgroup_attach_task(from_cgrp, tsk, false);
- if (retval)
- break;
- }
- percpu_up_write(&cgroup_threadgroup_rwsem);
- mutex_unlock(&cgroup_mutex);
-
- return retval;
-}
-EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
-
-static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- return __cgroup_procs_write(of, buf, nbytes, off, false);
-}
-
-static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- return __cgroup_procs_write(of, buf, nbytes, off, true);
-}
-
-static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- struct cgroup *cgrp;
-
- BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
-
- cgrp = cgroup_kn_lock_live(of->kn, false);
- if (!cgrp)
- return -ENODEV;
- spin_lock(&release_agent_path_lock);
- strlcpy(cgrp->root->release_agent_path, strstrip(buf),
- sizeof(cgrp->root->release_agent_path));
- spin_unlock(&release_agent_path_lock);
- cgroup_kn_unlock(of->kn);
- return nbytes;
-}
-
-static int cgroup_release_agent_show(struct seq_file *seq, void *v)
-{
- struct cgroup *cgrp = seq_css(seq)->cgroup;
-
- spin_lock(&release_agent_path_lock);
- seq_puts(seq, cgrp->root->release_agent_path);
- spin_unlock(&release_agent_path_lock);
- seq_putc(seq, '\n');
- return 0;
-}
-
-static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
-{
- seq_puts(seq, "0\n");
- return 0;
-}
-
-static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
-{
- struct cgroup_subsys *ss;
- bool printed = false;
- int ssid;
-
- do_each_subsys_mask(ss, ssid, ss_mask) {
- if (printed)
- seq_putc(seq, ' ');
- seq_printf(seq, "%s", ss->name);
- printed = true;
- } while_each_subsys_mask();
- if (printed)
- seq_putc(seq, '\n');
-}
-
-/* show controllers which are enabled from the parent */
-static int cgroup_controllers_show(struct seq_file *seq, void *v)
-{
- struct cgroup *cgrp = seq_css(seq)->cgroup;
-
- cgroup_print_ss_mask(seq, cgroup_control(cgrp));
- return 0;
-}
-
-/* show controllers which are enabled for a given cgroup's children */
-static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
-{
- struct cgroup *cgrp = seq_css(seq)->cgroup;
-
- cgroup_print_ss_mask(seq, cgrp->subtree_control);
- return 0;
-}
-
-/**
- * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
- * @cgrp: root of the subtree to update csses for
- *
- * @cgrp's control masks have changed and its subtree's css associations
- * need to be updated accordingly. This function looks up all css_sets
- * which are attached to the subtree, creates the matching updated css_sets
- * and migrates the tasks to the new ones.
- */
-static int cgroup_update_dfl_csses(struct cgroup *cgrp)
-{
- LIST_HEAD(preloaded_csets);
- struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
- struct cgroup_subsys_state *d_css;
- struct cgroup *dsct;
- struct css_set *src_cset;
- int ret;
-
- lockdep_assert_held(&cgroup_mutex);
-
- percpu_down_write(&cgroup_threadgroup_rwsem);
-
- /* look up all csses currently attached to @cgrp's subtree */
- spin_lock_irq(&css_set_lock);
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- struct cgrp_cset_link *link;
-
- list_for_each_entry(link, &dsct->cset_links, cset_link)
- cgroup_migrate_add_src(link->cset, dsct,
- &preloaded_csets);
- }
- spin_unlock_irq(&css_set_lock);
-
- /* NULL dst indicates self on default hierarchy */
- ret = cgroup_migrate_prepare_dst(&preloaded_csets);
- if (ret)
- goto out_finish;
-
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) {
- struct task_struct *task, *ntask;
-
- /* src_csets precede dst_csets, break on the first dst_cset */
- if (!src_cset->mg_src_cgrp)
- break;
-
- /* all tasks in src_csets need to be migrated */
- list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list)
- cgroup_taskset_add(task, &tset);
- }
- spin_unlock_irq(&css_set_lock);
-
- ret = cgroup_taskset_migrate(&tset, cgrp->root);
-out_finish:
- cgroup_migrate_finish(&preloaded_csets);
- percpu_up_write(&cgroup_threadgroup_rwsem);
- return ret;
-}
-
-/**
- * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
- * @cgrp: root of the target subtree
- *
- * Because css offlining is asynchronous, userland may try to re-enable a
- * controller while the previous css is still around. This function grabs
- * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
- */
-static void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
- __acquires(&cgroup_mutex)
-{
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- struct cgroup_subsys *ss;
- int ssid;
-
-restart:
- mutex_lock(&cgroup_mutex);
-
- cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
- DEFINE_WAIT(wait);
-
- if (!css || !percpu_ref_is_dying(&css->refcnt))
- continue;
-
- cgroup_get(dsct);
- prepare_to_wait(&dsct->offline_waitq, &wait,
- TASK_UNINTERRUPTIBLE);
-
- mutex_unlock(&cgroup_mutex);
- schedule();
- finish_wait(&dsct->offline_waitq, &wait);
-
- cgroup_put(dsct);
- goto restart;
- }
- }
-}
-
-/**
- * cgroup_save_control - save control masks of a subtree
- * @cgrp: root of the target subtree
- *
- * Save ->subtree_control and ->subtree_ss_mask to the respective old_
- * prefixed fields for @cgrp's subtree including @cgrp itself.
- */
-static void cgroup_save_control(struct cgroup *cgrp)
-{
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
-
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- dsct->old_subtree_control = dsct->subtree_control;
- dsct->old_subtree_ss_mask = dsct->subtree_ss_mask;
- }
-}
-
-/**
- * cgroup_propagate_control - refresh control masks of a subtree
- * @cgrp: root of the target subtree
- *
- * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
- * ->subtree_control and propagate controller availability through the
- * subtree so that descendants don't have unavailable controllers enabled.
- */
-static void cgroup_propagate_control(struct cgroup *cgrp)
-{
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
-
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- dsct->subtree_control &= cgroup_control(dsct);
- dsct->subtree_ss_mask =
- cgroup_calc_subtree_ss_mask(dsct->subtree_control,
- cgroup_ss_mask(dsct));
- }
-}
-
-/**
- * cgroup_restore_control - restore control masks of a subtree
- * @cgrp: root of the target subtree
- *
- * Restore ->subtree_control and ->subtree_ss_mask from the respective old_
- * prefixed fields for @cgrp's subtree including @cgrp itself.
- */
-static void cgroup_restore_control(struct cgroup *cgrp)
-{
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
-
- cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
- dsct->subtree_control = dsct->old_subtree_control;
- dsct->subtree_ss_mask = dsct->old_subtree_ss_mask;
- }
-}
-
-static bool css_visible(struct cgroup_subsys_state *css)
-{
- struct cgroup_subsys *ss = css->ss;
- struct cgroup *cgrp = css->cgroup;
-
- if (cgroup_control(cgrp) & (1 << ss->id))
- return true;
- if (!(cgroup_ss_mask(cgrp) & (1 << ss->id)))
- return false;
- return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl;
-}
-
-/**
- * cgroup_apply_control_enable - enable or show csses according to control
- * @cgrp: root of the target subtree
- *
- * Walk @cgrp's subtree and create new csses or make the existing ones
- * visible. A css is created invisible if it's being implicitly enabled
- * through dependency. An invisible css is made visible when the userland
- * explicitly enables it.
- *
- * Returns 0 on success, -errno on failure. On failure, csses which have
- * been processed already aren't cleaned up. The caller is responsible for
- * cleaning up with cgroup_apply_control_disble().
- */
-static int cgroup_apply_control_enable(struct cgroup *cgrp)
-{
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- struct cgroup_subsys *ss;
- int ssid, ret;
-
- cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
-
- WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt));
-
- if (!(cgroup_ss_mask(dsct) & (1 << ss->id)))
- continue;
-
- if (!css) {
- css = css_create(dsct, ss);
- if (IS_ERR(css))
- return PTR_ERR(css);
- }
-
- if (css_visible(css)) {
- ret = css_populate_dir(css);
- if (ret)
- return ret;
- }
- }
- }
-
- return 0;
-}
-
-/**
- * cgroup_apply_control_disable - kill or hide csses according to control
- * @cgrp: root of the target subtree
- *
- * Walk @cgrp's subtree and kill and hide csses so that they match
- * cgroup_ss_mask() and cgroup_visible_mask().
- *
- * A css is hidden when the userland requests it to be disabled while other
- * subsystems are still depending on it. The css must not actively control
- * resources and be in the vanilla state if it's made visible again later.
- * Controllers which may be depended upon should provide ->css_reset() for
- * this purpose.
- */
-static void cgroup_apply_control_disable(struct cgroup *cgrp)
-{
- struct cgroup *dsct;
- struct cgroup_subsys_state *d_css;
- struct cgroup_subsys *ss;
- int ssid;
-
- cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
- for_each_subsys(ss, ssid) {
- struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
-
- WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt));
-
- if (!css)
- continue;
-
- if (css->parent &&
- !(cgroup_ss_mask(dsct) & (1 << ss->id))) {
- kill_css(css);
- } else if (!css_visible(css)) {
- css_clear_dir(css);
- if (ss->css_reset)
- ss->css_reset(css);
- }
- }
- }
-}
-
-/**
- * cgroup_apply_control - apply control mask updates to the subtree
- * @cgrp: root of the target subtree
- *
- * subsystems can be enabled and disabled in a subtree using the following
- * steps.
- *
- * 1. Call cgroup_save_control() to stash the current state.
- * 2. Update ->subtree_control masks in the subtree as desired.
- * 3. Call cgroup_apply_control() to apply the changes.
- * 4. Optionally perform other related operations.
- * 5. Call cgroup_finalize_control() to finish up.
- *
- * This function implements step 3 and propagates the mask changes
- * throughout @cgrp's subtree, updates csses accordingly and perform
- * process migrations.
- */
-static int cgroup_apply_control(struct cgroup *cgrp)
-{
- int ret;
-
- cgroup_propagate_control(cgrp);
-
- ret = cgroup_apply_control_enable(cgrp);
- if (ret)
- return ret;
-
- /*
- * At this point, cgroup_e_css() results reflect the new csses
- * making the following cgroup_update_dfl_csses() properly update
- * css associations of all tasks in the subtree.
- */
- ret = cgroup_update_dfl_csses(cgrp);
- if (ret)
- return ret;
-
- return 0;
-}
-
-/**
- * cgroup_finalize_control - finalize control mask update
- * @cgrp: root of the target subtree
- * @ret: the result of the update
- *
- * Finalize control mask update. See cgroup_apply_control() for more info.
- */
-static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
-{
- if (ret) {
- cgroup_restore_control(cgrp);
- cgroup_propagate_control(cgrp);
- }
-
- cgroup_apply_control_disable(cgrp);
-}
-
-/* change the enabled child controllers for a cgroup in the default hierarchy */
-static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes,
- loff_t off)
-{
- u16 enable = 0, disable = 0;
- struct cgroup *cgrp, *child;
- struct cgroup_subsys *ss;
- char *tok;
- int ssid, ret;
-
- /*
- * Parse input - space separated list of subsystem names prefixed
- * with either + or -.
- */
- buf = strstrip(buf);
- while ((tok = strsep(&buf, " "))) {
- if (tok[0] == '\0')
- continue;
- do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) {
- if (!cgroup_ssid_enabled(ssid) ||
- strcmp(tok + 1, ss->name))
- continue;
-
- if (*tok == '+') {
- enable |= 1 << ssid;
- disable &= ~(1 << ssid);
- } else if (*tok == '-') {
- disable |= 1 << ssid;
- enable &= ~(1 << ssid);
- } else {
- return -EINVAL;
- }
- break;
- } while_each_subsys_mask();
- if (ssid == CGROUP_SUBSYS_COUNT)
- return -EINVAL;
- }
-
- cgrp = cgroup_kn_lock_live(of->kn, true);
- if (!cgrp)
- return -ENODEV;
-
- for_each_subsys(ss, ssid) {
- if (enable & (1 << ssid)) {
- if (cgrp->subtree_control & (1 << ssid)) {
- enable &= ~(1 << ssid);
- continue;
- }
-
- if (!(cgroup_control(cgrp) & (1 << ssid))) {
- ret = -ENOENT;
- goto out_unlock;
- }
- } else if (disable & (1 << ssid)) {
- if (!(cgrp->subtree_control & (1 << ssid))) {
- disable &= ~(1 << ssid);
- continue;
- }
-
- /* a child has it enabled? */
- cgroup_for_each_live_child(child, cgrp) {
- if (child->subtree_control & (1 << ssid)) {
- ret = -EBUSY;
- goto out_unlock;
- }
- }
- }
- }
-
- if (!enable && !disable) {
- ret = 0;
- goto out_unlock;
- }
-
- /*
- * Except for the root, subtree_control must be zero for a cgroup
- * with tasks so that child cgroups don't compete against tasks.
- */
- if (enable && cgroup_parent(cgrp)) {
- struct cgrp_cset_link *link;
-
- /*
- * Because namespaces pin csets too, @cgrp->cset_links
- * might not be empty even when @cgrp is empty. Walk and
- * verify each cset.
- */
- spin_lock_irq(&css_set_lock);
-
- ret = 0;
- list_for_each_entry(link, &cgrp->cset_links, cset_link) {
- if (css_set_populated(link->cset)) {
- ret = -EBUSY;
- break;
- }
- }
-
- spin_unlock_irq(&css_set_lock);
-
- if (ret)
- goto out_unlock;
- }
-
- /* save and update control masks and prepare csses */
- cgroup_save_control(cgrp);
-
- cgrp->subtree_control |= enable;
- cgrp->subtree_control &= ~disable;
-
- ret = cgroup_apply_control(cgrp);
-
- cgroup_finalize_control(cgrp, ret);
-
- kernfs_activate(cgrp->kn);
- ret = 0;
-out_unlock:
- cgroup_kn_unlock(of->kn);
- return ret ?: nbytes;
-}
-
-static int cgroup_events_show(struct seq_file *seq, void *v)
-{
- seq_printf(seq, "populated %d\n",
- cgroup_is_populated(seq_css(seq)->cgroup));
- return 0;
-}
-
-static int cgroup_file_open(struct kernfs_open_file *of)
-{
- struct cftype *cft = of->kn->priv;
-
- if (cft->open)
- return cft->open(of);
- return 0;
-}
-
-static void cgroup_file_release(struct kernfs_open_file *of)
-{
- struct cftype *cft = of->kn->priv;
-
- if (cft->release)
- cft->release(of);
-}
-
-static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off)
-{
- struct cgroup *cgrp = of->kn->parent->priv;
- struct cftype *cft = of->kn->priv;
- struct cgroup_subsys_state *css;
- int ret;
-
- if (cft->write)
- return cft->write(of, buf, nbytes, off);
-
- /*
- * kernfs guarantees that a file isn't deleted with operations in
- * flight, which means that the matching css is and stays alive and
- * doesn't need to be pinned. The RCU locking is not necessary
- * either. It's just for the convenience of using cgroup_css().
- */
- rcu_read_lock();
- css = cgroup_css(cgrp, cft->ss);
- rcu_read_unlock();
-
- if (cft->write_u64) {
- unsigned long long v;
- ret = kstrtoull(buf, 0, &v);
- if (!ret)
- ret = cft->write_u64(css, cft, v);
- } else if (cft->write_s64) {
- long long v;
- ret = kstrtoll(buf, 0, &v);
- if (!ret)
- ret = cft->write_s64(css, cft, v);
- } else {
- ret = -EINVAL;
- }
-
- return ret ?: nbytes;
-}
-
-static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
-{
- return seq_cft(seq)->seq_start(seq, ppos);
-}
-
-static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
-{
- return seq_cft(seq)->seq_next(seq, v, ppos);
-}
-
-static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
-{
- if (seq_cft(seq)->seq_stop)
- seq_cft(seq)->seq_stop(seq, v);
-}
-
-static int cgroup_seqfile_show(struct seq_file *m, void *arg)
-{
- struct cftype *cft = seq_cft(m);
- struct cgroup_subsys_state *css = seq_css(m);
-
- if (cft->seq_show)
- return cft->seq_show(m, arg);
-
- if (cft->read_u64)
- seq_printf(m, "%llu\n", cft->read_u64(css, cft));
- else if (cft->read_s64)
- seq_printf(m, "%lld\n", cft->read_s64(css, cft));
- else
- return -EINVAL;
- return 0;
-}
-
-static struct kernfs_ops cgroup_kf_single_ops = {
- .atomic_write_len = PAGE_SIZE,
- .open = cgroup_file_open,
- .release = cgroup_file_release,
- .write = cgroup_file_write,
- .seq_show = cgroup_seqfile_show,
-};
-
-static struct kernfs_ops cgroup_kf_ops = {
- .atomic_write_len = PAGE_SIZE,
- .open = cgroup_file_open,
- .release = cgroup_file_release,
- .write = cgroup_file_write,
- .seq_start = cgroup_seqfile_start,
- .seq_next = cgroup_seqfile_next,
- .seq_stop = cgroup_seqfile_stop,
- .seq_show = cgroup_seqfile_show,
-};
-
-/*
- * cgroup_rename - Only allow simple rename of directories in place.
- */
-static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
- const char *new_name_str)
-{
- struct cgroup *cgrp = kn->priv;
- int ret;
-
- if (kernfs_type(kn) != KERNFS_DIR)
- return -ENOTDIR;
- if (kn->parent != new_parent)
- return -EIO;
-
- /*
- * This isn't a proper migration and its usefulness is very
- * limited. Disallow on the default hierarchy.
- */
- if (cgroup_on_dfl(cgrp))
- return -EPERM;
-
- /*
- * We're gonna grab cgroup_mutex which nests outside kernfs
- * active_ref. kernfs_rename() doesn't require active_ref
- * protection. Break them before grabbing cgroup_mutex.
- */
- kernfs_break_active_protection(new_parent);
- kernfs_break_active_protection(kn);
-
- mutex_lock(&cgroup_mutex);
-
- ret = kernfs_rename(kn, new_parent, new_name_str);
- if (!ret)
- trace_cgroup_rename(cgrp);
-
- mutex_unlock(&cgroup_mutex);
-
- kernfs_unbreak_active_protection(kn);
- kernfs_unbreak_active_protection(new_parent);
- return ret;
-}
-
-/* set uid and gid of cgroup dirs and files to that of the creator */
-static int cgroup_kn_set_ugid(struct kernfs_node *kn)
-{
- struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
- .ia_uid = current_fsuid(),
- .ia_gid = current_fsgid(), };
-
- if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
- gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
- return 0;
-
- return kernfs_setattr(kn, &iattr);
-}
-
-static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
- struct cftype *cft)
-{
- char name[CGROUP_FILE_NAME_MAX];
- struct kernfs_node *kn;
- struct lock_class_key *key = NULL;
- int ret;
-
-#ifdef CONFIG_DEBUG_LOCK_ALLOC
- key = &cft->lockdep_key;
-#endif
- kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
- cgroup_file_mode(cft), 0, cft->kf_ops, cft,
- NULL, key);
- if (IS_ERR(kn))
- return PTR_ERR(kn);
-
- ret = cgroup_kn_set_ugid(kn);
- if (ret) {
- kernfs_remove(kn);
- return ret;
- }
-
- if (cft->file_offset) {
- struct cgroup_file *cfile = (void *)css + cft->file_offset;
-
- spin_lock_irq(&cgroup_file_kn_lock);
- cfile->kn = kn;
- spin_unlock_irq(&cgroup_file_kn_lock);
- }
-
- return 0;
-}
-
-/**
- * cgroup_addrm_files - add or remove files to a cgroup directory
- * @css: the target css
- * @cgrp: the target cgroup (usually css->cgroup)
- * @cfts: array of cftypes to be added
- * @is_add: whether to add or remove
- *
- * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
- * For removals, this function never fails.
- */
-static int cgroup_addrm_files(struct cgroup_subsys_state *css,
- struct cgroup *cgrp, struct cftype cfts[],
- bool is_add)
-{
- struct cftype *cft, *cft_end = NULL;
- int ret = 0;
-
- lockdep_assert_held(&cgroup_mutex);
-
-restart:
- for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
- /* does cft->flags tell us to skip this file on @cgrp? */
- if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
- continue;
- if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
- continue;
- if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
- continue;
- if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
- continue;
-
- if (is_add) {
- ret = cgroup_add_file(css, cgrp, cft);
- if (ret) {
- pr_warn("%s: failed to add %s, err=%d\n",
- __func__, cft->name, ret);
- cft_end = cft;
- is_add = false;
- goto restart;
- }
- } else {
- cgroup_rm_file(cgrp, cft);
- }
- }
- return ret;
-}
-
-static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
-{
- LIST_HEAD(pending);
- struct cgroup_subsys *ss = cfts[0].ss;
- struct cgroup *root = &ss->root->cgrp;
- struct cgroup_subsys_state *css;
- int ret = 0;
-
- lockdep_assert_held(&cgroup_mutex);
-
- /* add/rm files for all cgroups created before */
- css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
- struct cgroup *cgrp = css->cgroup;
-
- if (!(css->flags & CSS_VISIBLE))
- continue;
-
- ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
- if (ret)
- break;
- }
-
- if (is_add && !ret)
- kernfs_activate(root->kn);
- return ret;
-}
-
-static void cgroup_exit_cftypes(struct cftype *cfts)
-{
- struct cftype *cft;
-
- for (cft = cfts; cft->name[0] != '\0'; cft++) {
- /* free copy for custom atomic_write_len, see init_cftypes() */
- if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
- kfree(cft->kf_ops);
- cft->kf_ops = NULL;
- cft->ss = NULL;
-
- /* revert flags set by cgroup core while adding @cfts */
- cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
- }
-}
-
-static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
-{
- struct cftype *cft;
-
- for (cft = cfts; cft->name[0] != '\0'; cft++) {
- struct kernfs_ops *kf_ops;
-
- WARN_ON(cft->ss || cft->kf_ops);
-
- if (cft->seq_start)
- kf_ops = &cgroup_kf_ops;
- else
- kf_ops = &cgroup_kf_single_ops;
-
- /*
- * Ugh... if @cft wants a custom max_write_len, we need to
- * make a copy of kf_ops to set its atomic_write_len.
- */
- if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
- kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
- if (!kf_ops) {
- cgroup_exit_cftypes(cfts);
- return -ENOMEM;
- }
- kf_ops->atomic_write_len = cft->max_write_len;
- }
-
- cft->kf_ops = kf_ops;
- cft->ss = ss;
- }
-
- return 0;
-}
-
-static int cgroup_rm_cftypes_locked(struct cftype *cfts)
-{
- lockdep_assert_held(&cgroup_mutex);
-
- if (!cfts || !cfts[0].ss)
- return -ENOENT;
-
- list_del(&cfts->node);
- cgroup_apply_cftypes(cfts, false);
- cgroup_exit_cftypes(cfts);
- return 0;
-}
-
-/**
- * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Unregister @cfts. Files described by @cfts are removed from all
- * existing cgroups and all future cgroups won't have them either. This
- * function can be called anytime whether @cfts' subsys is attached or not.
- *
- * Returns 0 on successful unregistration, -ENOENT if @cfts is not
- * registered.
- */
-int cgroup_rm_cftypes(struct cftype *cfts)
-{
- int ret;
-
- mutex_lock(&cgroup_mutex);
- ret = cgroup_rm_cftypes_locked(cfts);
- mutex_unlock(&cgroup_mutex);
- return ret;
-}
-
-/**
- * cgroup_add_cftypes - add an array of cftypes to a subsystem
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Register @cfts to @ss. Files described by @cfts are created for all
- * existing cgroups to which @ss is attached and all future cgroups will
- * have them too. This function can be called anytime whether @ss is
- * attached or not.
- *
- * Returns 0 on successful registration, -errno on failure. Note that this
- * function currently returns 0 as long as @cfts registration is successful
- * even if some file creation attempts on existing cgroups fail.
- */
-static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
-{
- int ret;
-
- if (!cgroup_ssid_enabled(ss->id))
- return 0;
-
- if (!cfts || cfts[0].name[0] == '\0')
- return 0;
-
- ret = cgroup_init_cftypes(ss, cfts);
- if (ret)
- return ret;
-
- mutex_lock(&cgroup_mutex);
-
- list_add_tail(&cfts->node, &ss->cfts);
- ret = cgroup_apply_cftypes(cfts, true);
- if (ret)
- cgroup_rm_cftypes_locked(cfts);
-
- mutex_unlock(&cgroup_mutex);
- return ret;
-}
-
-/**
- * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Similar to cgroup_add_cftypes() but the added files are only used for
- * the default hierarchy.
- */
-int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
-{
- struct cftype *cft;
-
- for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
- cft->flags |= __CFTYPE_ONLY_ON_DFL;
- return cgroup_add_cftypes(ss, cfts);
-}
-
-/**
- * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
- * @ss: target cgroup subsystem
- * @cfts: zero-length name terminated array of cftypes
- *
- * Similar to cgroup_add_cftypes() but the added files are only used for
- * the legacy hierarchies.
- */
-int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
-{
- struct cftype *cft;
-
- for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
- cft->flags |= __CFTYPE_NOT_ON_DFL;
- return cgroup_add_cftypes(ss, cfts);
-}
-
-/**
- * cgroup_file_notify - generate a file modified event for a cgroup_file
- * @cfile: target cgroup_file
- *
- * @cfile must have been obtained by setting cftype->file_offset.
- */
-void cgroup_file_notify(struct cgroup_file *cfile)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&cgroup_file_kn_lock, flags);
- if (cfile->kn)
- kernfs_notify(cfile->kn);
- spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
-}
-
-/**
- * cgroup_task_count - count the number of tasks in a cgroup.
- * @cgrp: the cgroup in question
- *
- * Return the number of tasks in the cgroup. The returned number can be
- * higher than the actual number of tasks due to css_set references from
- * namespace roots and temporary usages.
- */
-static int cgroup_task_count(const struct cgroup *cgrp)
-{
- int count = 0;
- struct cgrp_cset_link *link;
-
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(link, &cgrp->cset_links, cset_link)
- count += atomic_read(&link->cset->refcount);
- spin_unlock_irq(&css_set_lock);
- return count;
-}
-
-/**
- * css_next_child - find the next child of a given css
- * @pos: the current position (%NULL to initiate traversal)
- * @parent: css whose children to walk
- *
- * This function returns the next child of @parent and should be called
- * under either cgroup_mutex or RCU read lock. The only requirement is
- * that @parent and @pos are accessible. The next sibling is guaranteed to
- * be returned regardless of their states.
- *
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
- */
-struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *parent)
-{
- struct cgroup_subsys_state *next;
-
- cgroup_assert_mutex_or_rcu_locked();
-
- /*
- * @pos could already have been unlinked from the sibling list.
- * Once a cgroup is removed, its ->sibling.next is no longer
- * updated when its next sibling changes. CSS_RELEASED is set when
- * @pos is taken off list, at which time its next pointer is valid,
- * and, as releases are serialized, the one pointed to by the next
- * pointer is guaranteed to not have started release yet. This
- * implies that if we observe !CSS_RELEASED on @pos in this RCU
- * critical section, the one pointed to by its next pointer is
- * guaranteed to not have finished its RCU grace period even if we
- * have dropped rcu_read_lock() inbetween iterations.
- *
- * If @pos has CSS_RELEASED set, its next pointer can't be
- * dereferenced; however, as each css is given a monotonically
- * increasing unique serial number and always appended to the
- * sibling list, the next one can be found by walking the parent's
- * children until the first css with higher serial number than
- * @pos's. While this path can be slower, it happens iff iteration
- * races against release and the race window is very small.
- */
- if (!pos) {
- next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
- } else if (likely(!(pos->flags & CSS_RELEASED))) {
- next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
- } else {
- list_for_each_entry_rcu(next, &parent->children, sibling)
- if (next->serial_nr > pos->serial_nr)
- break;
- }
-
- /*
- * @next, if not pointing to the head, can be dereferenced and is
- * the next sibling.
- */
- if (&next->sibling != &parent->children)
- return next;
- return NULL;
-}
-
-/**
- * css_next_descendant_pre - find the next descendant for pre-order walk
- * @pos: the current position (%NULL to initiate traversal)
- * @root: css whose descendants to walk
- *
- * To be used by css_for_each_descendant_pre(). Find the next descendant
- * to visit for pre-order traversal of @root's descendants. @root is
- * included in the iteration and the first node to be visited.
- *
- * While this function requires cgroup_mutex or RCU read locking, it
- * doesn't require the whole traversal to be contained in a single critical
- * section. This function will return the correct next descendant as long
- * as both @pos and @root are accessible and @pos is a descendant of @root.
- *
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
- */
-struct cgroup_subsys_state *
-css_next_descendant_pre(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *root)
-{
- struct cgroup_subsys_state *next;
-
- cgroup_assert_mutex_or_rcu_locked();
-
- /* if first iteration, visit @root */
- if (!pos)
- return root;
-
- /* visit the first child if exists */
- next = css_next_child(NULL, pos);
- if (next)
- return next;
-
- /* no child, visit my or the closest ancestor's next sibling */
- while (pos != root) {
- next = css_next_child(pos, pos->parent);
- if (next)
- return next;
- pos = pos->parent;
- }
-
- return NULL;
-}
-
-/**
- * css_rightmost_descendant - return the rightmost descendant of a css
- * @pos: css of interest
- *
- * Return the rightmost descendant of @pos. If there's no descendant, @pos
- * is returned. This can be used during pre-order traversal to skip
- * subtree of @pos.
- *
- * While this function requires cgroup_mutex or RCU read locking, it
- * doesn't require the whole traversal to be contained in a single critical
- * section. This function will return the correct rightmost descendant as
- * long as @pos is accessible.
- */
-struct cgroup_subsys_state *
-css_rightmost_descendant(struct cgroup_subsys_state *pos)
-{
- struct cgroup_subsys_state *last, *tmp;
-
- cgroup_assert_mutex_or_rcu_locked();
-
- do {
- last = pos;
- /* ->prev isn't RCU safe, walk ->next till the end */
- pos = NULL;
- css_for_each_child(tmp, last)
- pos = tmp;
- } while (pos);
-
- return last;
-}
-
-static struct cgroup_subsys_state *
-css_leftmost_descendant(struct cgroup_subsys_state *pos)
-{
- struct cgroup_subsys_state *last;
-
- do {
- last = pos;
- pos = css_next_child(NULL, pos);
- } while (pos);
-
- return last;
-}
-
-/**
- * css_next_descendant_post - find the next descendant for post-order walk
- * @pos: the current position (%NULL to initiate traversal)
- * @root: css whose descendants to walk
- *
- * To be used by css_for_each_descendant_post(). Find the next descendant
- * to visit for post-order traversal of @root's descendants. @root is
- * included in the iteration and the last node to be visited.
- *
- * While this function requires cgroup_mutex or RCU read locking, it
- * doesn't require the whole traversal to be contained in a single critical
- * section. This function will return the correct next descendant as long
- * as both @pos and @cgroup are accessible and @pos is a descendant of
- * @cgroup.
- *
- * If a subsystem synchronizes ->css_online() and the start of iteration, a
- * css which finished ->css_online() is guaranteed to be visible in the
- * future iterations and will stay visible until the last reference is put.
- * A css which hasn't finished ->css_online() or already finished
- * ->css_offline() may show up during traversal. It's each subsystem's
- * responsibility to synchronize against on/offlining.
- */
-struct cgroup_subsys_state *
-css_next_descendant_post(struct cgroup_subsys_state *pos,
- struct cgroup_subsys_state *root)
-{
- struct cgroup_subsys_state *next;
-
- cgroup_assert_mutex_or_rcu_locked();
-
- /* if first iteration, visit leftmost descendant which may be @root */
- if (!pos)
- return css_leftmost_descendant(root);
-
- /* if we visited @root, we're done */
- if (pos == root)
- return NULL;
-
- /* if there's an unvisited sibling, visit its leftmost descendant */
- next = css_next_child(pos, pos->parent);
- if (next)
- return css_leftmost_descendant(next);
-
- /* no sibling left, visit parent */
- return pos->parent;
-}
-
-/**
- * css_has_online_children - does a css have online children
- * @css: the target css
- *
- * Returns %true if @css has any online children; otherwise, %false. This
- * function can be called from any context but the caller is responsible
- * for synchronizing against on/offlining as necessary.
- */
-bool css_has_online_children(struct cgroup_subsys_state *css)
-{
- struct cgroup_subsys_state *child;
- bool ret = false;
-
- rcu_read_lock();
- css_for_each_child(child, css) {
- if (child->flags & CSS_ONLINE) {
- ret = true;
- break;
- }
- }
- rcu_read_unlock();
- return ret;
-}
-
-/**
- * css_task_iter_advance_css_set - advance a task itererator to the next css_set
- * @it: the iterator to advance
- *
- * Advance @it to the next css_set to walk.
- */
-static void css_task_iter_advance_css_set(struct css_task_iter *it)
-{
- struct list_head *l = it->cset_pos;
- struct cgrp_cset_link *link;
- struct css_set *cset;
-
- lockdep_assert_held(&css_set_lock);
-
- /* Advance to the next non-empty css_set */
- do {
- l = l->next;
- if (l == it->cset_head) {
- it->cset_pos = NULL;
- it->task_pos = NULL;
- return;
- }
-
- if (it->ss) {
- cset = container_of(l, struct css_set,
- e_cset_node[it->ss->id]);
- } else {
- link = list_entry(l, struct cgrp_cset_link, cset_link);
- cset = link->cset;
- }
- } while (!css_set_populated(cset));
-
- it->cset_pos = l;
-
- if (!list_empty(&cset->tasks))
- it->task_pos = cset->tasks.next;
- else
- it->task_pos = cset->mg_tasks.next;
-
- it->tasks_head = &cset->tasks;
- it->mg_tasks_head = &cset->mg_tasks;
-
- /*
- * We don't keep css_sets locked across iteration steps and thus
- * need to take steps to ensure that iteration can be resumed after
- * the lock is re-acquired. Iteration is performed at two levels -
- * css_sets and tasks in them.
- *
- * Once created, a css_set never leaves its cgroup lists, so a
- * pinned css_set is guaranteed to stay put and we can resume
- * iteration afterwards.
- *
- * Tasks may leave @cset across iteration steps. This is resolved
- * by registering each iterator with the css_set currently being
- * walked and making css_set_move_task() advance iterators whose
- * next task is leaving.
- */
- if (it->cur_cset) {
- list_del(&it->iters_node);
- put_css_set_locked(it->cur_cset);
- }
- get_css_set(cset);
- it->cur_cset = cset;
- list_add(&it->iters_node, &cset->task_iters);
-}
-
-static void css_task_iter_advance(struct css_task_iter *it)
-{
- struct list_head *l = it->task_pos;
-
- lockdep_assert_held(&css_set_lock);
- WARN_ON_ONCE(!l);
-
- /*
- * Advance iterator to find next entry. cset->tasks is consumed
- * first and then ->mg_tasks. After ->mg_tasks, we move onto the
- * next cset.
- */
- l = l->next;
-
- if (l == it->tasks_head)
- l = it->mg_tasks_head->next;
-
- if (l == it->mg_tasks_head)
- css_task_iter_advance_css_set(it);
- else
- it->task_pos = l;
-}
-
-/**
- * css_task_iter_start - initiate task iteration
- * @css: the css to walk tasks of
- * @it: the task iterator to use
- *
- * Initiate iteration through the tasks of @css. The caller can call
- * css_task_iter_next() to walk through the tasks until the function
- * returns NULL. On completion of iteration, css_task_iter_end() must be
- * called.
- */
-void css_task_iter_start(struct cgroup_subsys_state *css,
- struct css_task_iter *it)
-{
- /* no one should try to iterate before mounting cgroups */
- WARN_ON_ONCE(!use_task_css_set_links);
-
- memset(it, 0, sizeof(*it));
-
- spin_lock_irq(&css_set_lock);
-
- it->ss = css->ss;
-
- if (it->ss)
- it->cset_pos = &css->cgroup->e_csets[css->ss->id];
- else
- it->cset_pos = &css->cgroup->cset_links;
-
- it->cset_head = it->cset_pos;
-
- css_task_iter_advance_css_set(it);
-
- spin_unlock_irq(&css_set_lock);
-}
-
-/**
- * css_task_iter_next - return the next task for the iterator
- * @it: the task iterator being iterated
- *
- * The "next" function for task iteration. @it should have been
- * initialized via css_task_iter_start(). Returns NULL when the iteration
- * reaches the end.
- */
-struct task_struct *css_task_iter_next(struct css_task_iter *it)
-{
- if (it->cur_task) {
- put_task_struct(it->cur_task);
- it->cur_task = NULL;
- }
-
- spin_lock_irq(&css_set_lock);
-
- if (it->task_pos) {
- it->cur_task = list_entry(it->task_pos, struct task_struct,
- cg_list);
- get_task_struct(it->cur_task);
- css_task_iter_advance(it);
- }
-
- spin_unlock_irq(&css_set_lock);
-
- return it->cur_task;
-}
-
-/**
- * css_task_iter_end - finish task iteration
- * @it: the task iterator to finish
- *
- * Finish task iteration started by css_task_iter_start().
- */
-void css_task_iter_end(struct css_task_iter *it)
-{
- if (it->cur_cset) {
- spin_lock_irq(&css_set_lock);
- list_del(&it->iters_node);
- put_css_set_locked(it->cur_cset);
- spin_unlock_irq(&css_set_lock);
- }
-
- if (it->cur_task)
- put_task_struct(it->cur_task);
-}
-
-/**
- * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
- * @to: cgroup to which the tasks will be moved
- * @from: cgroup in which the tasks currently reside
- *
- * Locking rules between cgroup_post_fork() and the migration path
- * guarantee that, if a task is forking while being migrated, the new child
- * is guaranteed to be either visible in the source cgroup after the
- * parent's migration is complete or put into the target cgroup. No task
- * can slip out of migration through forking.
- */
-int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
-{
- LIST_HEAD(preloaded_csets);
- struct cgrp_cset_link *link;
- struct css_task_iter it;
- struct task_struct *task;
- int ret;
-
- if (cgroup_on_dfl(to))
- return -EINVAL;
-
- if (!cgroup_may_migrate_to(to))
- return -EBUSY;
-
- mutex_lock(&cgroup_mutex);
-
- percpu_down_write(&cgroup_threadgroup_rwsem);
-
- /* all tasks in @from are being moved, all csets are source */
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(link, &from->cset_links, cset_link)
- cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
- spin_unlock_irq(&css_set_lock);
-
- ret = cgroup_migrate_prepare_dst(&preloaded_csets);
- if (ret)
- goto out_err;
-
- /*
- * Migrate tasks one-by-one until @from is empty. This fails iff
- * ->can_attach() fails.
- */
- do {
- css_task_iter_start(&from->self, &it);
- task = css_task_iter_next(&it);
- if (task)
- get_task_struct(task);
- css_task_iter_end(&it);
-
- if (task) {
- ret = cgroup_migrate(task, false, to->root);
- if (!ret)
- trace_cgroup_transfer_tasks(to, task, false);
- put_task_struct(task);
- }
- } while (task && !ret);
-out_err:
- cgroup_migrate_finish(&preloaded_csets);
- percpu_up_write(&cgroup_threadgroup_rwsem);
- mutex_unlock(&cgroup_mutex);
- return ret;
-}
-
-static void cgroup_procs_release(struct kernfs_open_file *of)
-{
- if (of->priv) {
- css_task_iter_end(of->priv);
- kfree(of->priv);
- }
-}
-
-static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos)
-{
- struct kernfs_open_file *of = s->private;
- struct css_task_iter *it = of->priv;
- struct task_struct *task;
-
- do {
- task = css_task_iter_next(it);
- } while (task && !thread_group_leader(task));
-
- return task;
-}
-
-static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
-{
- struct kernfs_open_file *of = s->private;
- struct cgroup *cgrp = seq_css(s)->cgroup;
- struct css_task_iter *it = of->priv;
-
- /*
- * When a seq_file is seeked, it's always traversed sequentially
- * from position 0, so we can simply keep iterating on !0 *pos.
- */
- if (!it) {
- if (WARN_ON_ONCE((*pos)++))
- return ERR_PTR(-EINVAL);
-
- it = kzalloc(sizeof(*it), GFP_KERNEL);
- if (!it)
- return ERR_PTR(-ENOMEM);
- of->priv = it;
- css_task_iter_start(&cgrp->self, it);
- } else if (!(*pos)++) {
- css_task_iter_end(it);
- css_task_iter_start(&cgrp->self, it);
- }
-
- return cgroup_procs_next(s, NULL, NULL);
-}
-
-static int cgroup_procs_show(struct seq_file *s, void *v)
-{
- seq_printf(s, "%d\n", task_tgid_vnr(v));
- return 0;
-}
-
-/*
- * Stuff for reading the 'tasks'/'procs' files.
- *
- * Reading this file can return large amounts of data if a cgroup has
- * *lots* of attached tasks. So it may need several calls to read(),
- * but we cannot guarantee that the information we produce is correct
- * unless we produce it entirely atomically.
- *
- */
-
-/* which pidlist file are we talking about? */
-enum cgroup_filetype {
- CGROUP_FILE_PROCS,
- CGROUP_FILE_TASKS,
-};
-
-/*
- * A pidlist is a list of pids that virtually represents the contents of one
- * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
- * a pair (one each for procs, tasks) for each pid namespace that's relevant
- * to the cgroup.
- */
-struct cgroup_pidlist {
- /*
- * used to find which pidlist is wanted. doesn't change as long as
- * this particular list stays in the list.
- */
- struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
- /* array of xids */
- pid_t *list;
- /* how many elements the above list has */
- int length;
- /* each of these stored in a list by its cgroup */
- struct list_head links;
- /* pointer to the cgroup we belong to, for list removal purposes */
- struct cgroup *owner;
- /* for delayed destruction */
- struct delayed_work destroy_dwork;
-};
-
-/*
- * The following two functions "fix" the issue where there are more pids
- * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
- * TODO: replace with a kernel-wide solution to this problem
- */
-#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
-static void *pidlist_allocate(int count)
-{
- if (PIDLIST_TOO_LARGE(count))
- return vmalloc(count * sizeof(pid_t));
- else
- return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
-}
-
-static void pidlist_free(void *p)
-{
- kvfree(p);
-}
-
-/*
- * Used to destroy all pidlists lingering waiting for destroy timer. None
- * should be left afterwards.
- */
-static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
-{
- struct cgroup_pidlist *l, *tmp_l;
-
- mutex_lock(&cgrp->pidlist_mutex);
- list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
- mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
- mutex_unlock(&cgrp->pidlist_mutex);
-
- flush_workqueue(cgroup_pidlist_destroy_wq);
- BUG_ON(!list_empty(&cgrp->pidlists));
-}
-
-static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
-{
- struct delayed_work *dwork = to_delayed_work(work);
- struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
- destroy_dwork);
- struct cgroup_pidlist *tofree = NULL;
-
- mutex_lock(&l->owner->pidlist_mutex);
-
- /*
- * Destroy iff we didn't get queued again. The state won't change
- * as destroy_dwork can only be queued while locked.
- */
- if (!delayed_work_pending(dwork)) {
- list_del(&l->links);
- pidlist_free(l->list);
- put_pid_ns(l->key.ns);
- tofree = l;
- }
-
- mutex_unlock(&l->owner->pidlist_mutex);
- kfree(tofree);
-}
-
-/*
- * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
- * Returns the number of unique elements.
- */
-static int pidlist_uniq(pid_t *list, int length)
-{
- int src, dest = 1;
-
- /*
- * we presume the 0th element is unique, so i starts at 1. trivial
- * edge cases first; no work needs to be done for either
- */
- if (length == 0 || length == 1)
- return length;
- /* src and dest walk down the list; dest counts unique elements */
- for (src = 1; src < length; src++) {
- /* find next unique element */
- while (list[src] == list[src-1]) {
- src++;
- if (src == length)
- goto after;
- }
- /* dest always points to where the next unique element goes */
- list[dest] = list[src];
- dest++;
- }
-after:
- return dest;
-}
-
-/*
- * The two pid files - task and cgroup.procs - guaranteed that the result
- * is sorted, which forced this whole pidlist fiasco. As pid order is
- * different per namespace, each namespace needs differently sorted list,
- * making it impossible to use, for example, single rbtree of member tasks
- * sorted by task pointer. As pidlists can be fairly large, allocating one
- * per open file is dangerous, so cgroup had to implement shared pool of
- * pidlists keyed by cgroup and namespace.
- */
-static int cmppid(const void *a, const void *b)
-{
- return *(pid_t *)a - *(pid_t *)b;
-}
-
-static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
- enum cgroup_filetype type)
-{
- struct cgroup_pidlist *l;
- /* don't need task_nsproxy() if we're looking at ourself */
- struct pid_namespace *ns = task_active_pid_ns(current);
-
- lockdep_assert_held(&cgrp->pidlist_mutex);
-
- list_for_each_entry(l, &cgrp->pidlists, links)
- if (l->key.type == type && l->key.ns == ns)
- return l;
- return NULL;
-}
-
-/*
- * find the appropriate pidlist for our purpose (given procs vs tasks)
- * returns with the lock on that pidlist already held, and takes care
- * of the use count, or returns NULL with no locks held if we're out of
- * memory.
- */
-static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
- enum cgroup_filetype type)
-{
- struct cgroup_pidlist *l;
-
- lockdep_assert_held(&cgrp->pidlist_mutex);
-
- l = cgroup_pidlist_find(cgrp, type);
- if (l)
- return l;
-
- /* entry not found; create a new one */
- l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
- if (!l)
- return l;
-
- INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
- l->key.type = type;
- /* don't need task_nsproxy() if we're looking at ourself */
- l->key.ns = get_pid_ns(task_active_pid_ns(current));
- l->owner = cgrp;
- list_add(&l->links, &cgrp->pidlists);
- return l;
-}
-
-/*
- * Load a cgroup's pidarray with either procs' tgids or tasks' pids
- */
-static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
- struct cgroup_pidlist **lp)
-{
- pid_t *array;
- int length;
- int pid, n = 0; /* used for populating the array */
- struct css_task_iter it;
- struct task_struct *tsk;
- struct cgroup_pidlist *l;
-
- lockdep_assert_held(&cgrp->pidlist_mutex);
-
- /*
- * If cgroup gets more users after we read count, we won't have
- * enough space - tough. This race is indistinguishable to the
- * caller from the case that the additional cgroup users didn't
- * show up until sometime later on.
- */
- length = cgroup_task_count(cgrp);
- array = pidlist_allocate(length);
- if (!array)
- return -ENOMEM;
- /* now, populate the array */
- css_task_iter_start(&cgrp->self, &it);
- while ((tsk = css_task_iter_next(&it))) {
- if (unlikely(n == length))
- break;
- /* get tgid or pid for procs or tasks file respectively */
- if (type == CGROUP_FILE_PROCS)
- pid = task_tgid_vnr(tsk);
- else
- pid = task_pid_vnr(tsk);
- if (pid > 0) /* make sure to only use valid results */
- array[n++] = pid;
- }
- css_task_iter_end(&it);
- length = n;
- /* now sort & (if procs) strip out duplicates */
- sort(array, length, sizeof(pid_t), cmppid, NULL);
- if (type == CGROUP_FILE_PROCS)
- length = pidlist_uniq(array, length);
-
- l = cgroup_pidlist_find_create(cgrp, type);
- if (!l) {
- pidlist_free(array);
- return -ENOMEM;
- }
-
- /* store array, freeing old if necessary */
- pidlist_free(l->list);
- l->list = array;
- l->length = length;
- *lp = l;
- return 0;
-}
-
-/**
- * cgroupstats_build - build and fill cgroupstats
- * @stats: cgroupstats to fill information into
- * @dentry: A dentry entry belonging to the cgroup for which stats have
- * been requested.
- *
- * Build and fill cgroupstats so that taskstats can export it to user
- * space.
- */
-int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
-{
- struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
- struct cgroup *cgrp;
- struct css_task_iter it;
- struct task_struct *tsk;
-
- /* it should be kernfs_node belonging to cgroupfs and is a directory */
- if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
- kernfs_type(kn) != KERNFS_DIR)
- return -EINVAL;
-
- mutex_lock(&cgroup_mutex);
-
- /*
- * We aren't being called from kernfs and there's no guarantee on
- * @kn->priv's validity. For this and css_tryget_online_from_dir(),
- * @kn->priv is RCU safe. Let's do the RCU dancing.
- */
- rcu_read_lock();
- cgrp = rcu_dereference(kn->priv);
- if (!cgrp || cgroup_is_dead(cgrp)) {
- rcu_read_unlock();
- mutex_unlock(&cgroup_mutex);
- return -ENOENT;
- }
- rcu_read_unlock();
-
- css_task_iter_start(&cgrp->self, &it);
- while ((tsk = css_task_iter_next(&it))) {
- switch (tsk->state) {
- case TASK_RUNNING:
- stats->nr_running++;
- break;
- case TASK_INTERRUPTIBLE:
- stats->nr_sleeping++;
- break;
- case TASK_UNINTERRUPTIBLE:
- stats->nr_uninterruptible++;
- break;
- case TASK_STOPPED:
- stats->nr_stopped++;
- break;
- default:
- if (delayacct_is_task_waiting_on_io(tsk))
- stats->nr_io_wait++;
- break;
- }
- }
- css_task_iter_end(&it);
-
- mutex_unlock(&cgroup_mutex);
- return 0;
-}
-
-
-/*
- * seq_file methods for the tasks/procs files. The seq_file position is the
- * next pid to display; the seq_file iterator is a pointer to the pid
- * in the cgroup->l->list array.
- */
-
-static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
-{
- /*
- * Initially we receive a position value that corresponds to
- * one more than the last pid shown (or 0 on the first call or
- * after a seek to the start). Use a binary-search to find the
- * next pid to display, if any
- */
- struct kernfs_open_file *of = s->private;
- struct cgroup *cgrp = seq_css(s)->cgroup;
- struct cgroup_pidlist *l;
- enum cgroup_filetype type = seq_cft(s)->private;
- int index = 0, pid = *pos;
- int *iter, ret;
-
- mutex_lock(&cgrp->pidlist_mutex);
-
- /*
- * !NULL @of->priv indicates that this isn't the first start()
- * after open. If the matching pidlist is around, we can use that.
- * Look for it. Note that @of->priv can't be used directly. It
- * could already have been destroyed.
- */
- if (of->priv)
- of->priv = cgroup_pidlist_find(cgrp, type);
-
- /*
- * Either this is the first start() after open or the matching
- * pidlist has been destroyed inbetween. Create a new one.
- */
- if (!of->priv) {
- ret = pidlist_array_load(cgrp, type,
- (struct cgroup_pidlist **)&of->priv);
- if (ret)
- return ERR_PTR(ret);
- }
- l = of->priv;
-
- if (pid) {
- int end = l->length;
-
- while (index < end) {
- int mid = (index + end) / 2;
- if (l->list[mid] == pid) {
- index = mid;
- break;
- } else if (l->list[mid] <= pid)
- index = mid + 1;
- else
- end = mid;
- }
- }
- /* If we're off the end of the array, we're done */
- if (index >= l->length)
- return NULL;
- /* Update the abstract position to be the actual pid that we found */
- iter = l->list + index;
- *pos = *iter;
- return iter;
-}
-
-static void cgroup_pidlist_stop(struct seq_file *s, void *v)
-{
- struct kernfs_open_file *of = s->private;
- struct cgroup_pidlist *l = of->priv;
-
- if (l)
- mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
- CGROUP_PIDLIST_DESTROY_DELAY);
- mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
-}
-
-static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
-{
- struct kernfs_open_file *of = s->private;
- struct cgroup_pidlist *l = of->priv;
- pid_t *p = v;
- pid_t *end = l->list + l->length;
- /*
- * Advance to the next pid in the array. If this goes off the
- * end, we're done
- */
- p++;
- if (p >= end) {
- return NULL;
- } else {
- *pos = *p;
- return p;
- }
-}
-
-static int cgroup_pidlist_show(struct seq_file *s, void *v)
-{
- seq_printf(s, "%d\n", *(int *)v);
-
- return 0;
-}
-
-static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- return notify_on_release(css->cgroup);
-}
-
-static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- if (val)
- set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
- else
- clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
- return 0;
-}
-
-static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
-}
-
-static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
- struct cftype *cft, u64 val)
-{
- if (val)
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
- else
- clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
- return 0;
-}
-
-/* cgroup core interface files for the default hierarchy */
-static struct cftype cgroup_dfl_base_files[] = {
- {
- .name = "cgroup.procs",
- .file_offset = offsetof(struct cgroup, procs_file),
- .release = cgroup_procs_release,
- .seq_start = cgroup_procs_start,
- .seq_next = cgroup_procs_next,
- .seq_show = cgroup_procs_show,
- .write = cgroup_procs_write,
- },
- {
- .name = "cgroup.controllers",
- .seq_show = cgroup_controllers_show,
- },
- {
- .name = "cgroup.subtree_control",
- .seq_show = cgroup_subtree_control_show,
- .write = cgroup_subtree_control_write,
- },
- {
- .name = "cgroup.events",
- .flags = CFTYPE_NOT_ON_ROOT,
- .file_offset = offsetof(struct cgroup, events_file),
- .seq_show = cgroup_events_show,
- },
- { } /* terminate */
-};
-
-/* cgroup core interface files for the legacy hierarchies */
-static struct cftype cgroup_legacy_base_files[] = {
- {
- .name = "cgroup.procs",
- .seq_start = cgroup_pidlist_start,
- .seq_next = cgroup_pidlist_next,
- .seq_stop = cgroup_pidlist_stop,
- .seq_show = cgroup_pidlist_show,
- .private = CGROUP_FILE_PROCS,
- .write = cgroup_procs_write,
- },
- {
- .name = "cgroup.clone_children",
- .read_u64 = cgroup_clone_children_read,
- .write_u64 = cgroup_clone_children_write,
- },
- {
- .name = "cgroup.sane_behavior",
- .flags = CFTYPE_ONLY_ON_ROOT,
- .seq_show = cgroup_sane_behavior_show,
- },
- {
- .name = "tasks",
- .seq_start = cgroup_pidlist_start,
- .seq_next = cgroup_pidlist_next,
- .seq_stop = cgroup_pidlist_stop,
- .seq_show = cgroup_pidlist_show,
- .private = CGROUP_FILE_TASKS,
- .write = cgroup_tasks_write,
- },
- {
- .name = "notify_on_release",
- .read_u64 = cgroup_read_notify_on_release,
- .write_u64 = cgroup_write_notify_on_release,
- },
- {
- .name = "release_agent",
- .flags = CFTYPE_ONLY_ON_ROOT,
- .seq_show = cgroup_release_agent_show,
- .write = cgroup_release_agent_write,
- .max_write_len = PATH_MAX - 1,
- },
- { } /* terminate */
-};
-
-/*
- * css destruction is four-stage process.
- *
- * 1. Destruction starts. Killing of the percpu_ref is initiated.
- * Implemented in kill_css().
- *
- * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
- * and thus css_tryget_online() is guaranteed to fail, the css can be
- * offlined by invoking offline_css(). After offlining, the base ref is
- * put. Implemented in css_killed_work_fn().
- *
- * 3. When the percpu_ref reaches zero, the only possible remaining
- * accessors are inside RCU read sections. css_release() schedules the
- * RCU callback.
- *
- * 4. After the grace period, the css can be freed. Implemented in
- * css_free_work_fn().
- *
- * It is actually hairier because both step 2 and 4 require process context
- * and thus involve punting to css->destroy_work adding two additional
- * steps to the already complex sequence.
- */
-static void css_free_work_fn(struct work_struct *work)
-{
- struct cgroup_subsys_state *css =
- container_of(work, struct cgroup_subsys_state, destroy_work);
- struct cgroup_subsys *ss = css->ss;
- struct cgroup *cgrp = css->cgroup;
-
- percpu_ref_exit(&css->refcnt);
-
- if (ss) {
- /* css free path */
- struct cgroup_subsys_state *parent = css->parent;
- int id = css->id;
-
- ss->css_free(css);
- cgroup_idr_remove(&ss->css_idr, id);
- cgroup_put(cgrp);
-
- if (parent)
- css_put(parent);
- } else {
- /* cgroup free path */
- atomic_dec(&cgrp->root->nr_cgrps);
- cgroup_pidlist_destroy_all(cgrp);
- cancel_work_sync(&cgrp->release_agent_work);
-
- if (cgroup_parent(cgrp)) {
- /*
- * We get a ref to the parent, and put the ref when
- * this cgroup is being freed, so it's guaranteed
- * that the parent won't be destroyed before its
- * children.
- */
- cgroup_put(cgroup_parent(cgrp));
- kernfs_put(cgrp->kn);
- kfree(cgrp);
- } else {
- /*
- * This is root cgroup's refcnt reaching zero,
- * which indicates that the root should be
- * released.
- */
- cgroup_destroy_root(cgrp->root);
- }
- }
-}
-
-static void css_free_rcu_fn(struct rcu_head *rcu_head)
-{
- struct cgroup_subsys_state *css =
- container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
-
- INIT_WORK(&css->destroy_work, css_free_work_fn);
- queue_work(cgroup_destroy_wq, &css->destroy_work);
-}
-
-static void css_release_work_fn(struct work_struct *work)
-{
- struct cgroup_subsys_state *css =
- container_of(work, struct cgroup_subsys_state, destroy_work);
- struct cgroup_subsys *ss = css->ss;
- struct cgroup *cgrp = css->cgroup;
-
- mutex_lock(&cgroup_mutex);
-
- css->flags |= CSS_RELEASED;
- list_del_rcu(&css->sibling);
-
- if (ss) {
- /* css release path */
- cgroup_idr_replace(&ss->css_idr, NULL, css->id);
- if (ss->css_released)
- ss->css_released(css);
- } else {
- /* cgroup release path */
- trace_cgroup_release(cgrp);
-
- cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
- cgrp->id = -1;
-
- /*
- * There are two control paths which try to determine
- * cgroup from dentry without going through kernfs -
- * cgroupstats_build() and css_tryget_online_from_dir().
- * Those are supported by RCU protecting clearing of
- * cgrp->kn->priv backpointer.
- */
- if (cgrp->kn)
- RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
- NULL);
-
- cgroup_bpf_put(cgrp);
- }
-
- mutex_unlock(&cgroup_mutex);
-
- call_rcu(&css->rcu_head, css_free_rcu_fn);
-}
-
-static void css_release(struct percpu_ref *ref)
-{
- struct cgroup_subsys_state *css =
- container_of(ref, struct cgroup_subsys_state, refcnt);
-
- INIT_WORK(&css->destroy_work, css_release_work_fn);
- queue_work(cgroup_destroy_wq, &css->destroy_work);
-}
-
-static void init_and_link_css(struct cgroup_subsys_state *css,
- struct cgroup_subsys *ss, struct cgroup *cgrp)
-{
- lockdep_assert_held(&cgroup_mutex);
-
- cgroup_get(cgrp);
-
- memset(css, 0, sizeof(*css));
- css->cgroup = cgrp;
- css->ss = ss;
- css->id = -1;
- INIT_LIST_HEAD(&css->sibling);
- INIT_LIST_HEAD(&css->children);
- css->serial_nr = css_serial_nr_next++;
- atomic_set(&css->online_cnt, 0);
-
- if (cgroup_parent(cgrp)) {
- css->parent = cgroup_css(cgroup_parent(cgrp), ss);
- css_get(css->parent);
- }
-
- BUG_ON(cgroup_css(cgrp, ss));
-}
-
-/* invoke ->css_online() on a new CSS and mark it online if successful */
-static int online_css(struct cgroup_subsys_state *css)
-{
- struct cgroup_subsys *ss = css->ss;
- int ret = 0;
-
- lockdep_assert_held(&cgroup_mutex);
-
- if (ss->css_online)
- ret = ss->css_online(css);
- if (!ret) {
- css->flags |= CSS_ONLINE;
- rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
-
- atomic_inc(&css->online_cnt);
- if (css->parent)
- atomic_inc(&css->parent->online_cnt);
- }
- return ret;
-}
-
-/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
-static void offline_css(struct cgroup_subsys_state *css)
-{
- struct cgroup_subsys *ss = css->ss;
-
- lockdep_assert_held(&cgroup_mutex);
-
- if (!(css->flags & CSS_ONLINE))
- return;
-
- if (ss->css_reset)
- ss->css_reset(css);
-
- if (ss->css_offline)
- ss->css_offline(css);
-
- css->flags &= ~CSS_ONLINE;
- RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
-
- wake_up_all(&css->cgroup->offline_waitq);
-}
-
-/**
- * css_create - create a cgroup_subsys_state
- * @cgrp: the cgroup new css will be associated with
- * @ss: the subsys of new css
- *
- * Create a new css associated with @cgrp - @ss pair. On success, the new
- * css is online and installed in @cgrp. This function doesn't create the
- * interface files. Returns 0 on success, -errno on failure.
- */
-static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
- struct cgroup_subsys *ss)
-{
- struct cgroup *parent = cgroup_parent(cgrp);
- struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
- struct cgroup_subsys_state *css;
- int err;
-
- lockdep_assert_held(&cgroup_mutex);
-
- css = ss->css_alloc(parent_css);
- if (!css)
- css = ERR_PTR(-ENOMEM);
- if (IS_ERR(css))
- return css;
-
- init_and_link_css(css, ss, cgrp);
-
- err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
- if (err)
- goto err_free_css;
-
- err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
- if (err < 0)
- goto err_free_css;
- css->id = err;
-
- /* @css is ready to be brought online now, make it visible */
- list_add_tail_rcu(&css->sibling, &parent_css->children);
- cgroup_idr_replace(&ss->css_idr, css, css->id);
-
- err = online_css(css);
- if (err)
- goto err_list_del;
-
- if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
- cgroup_parent(parent)) {
- pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
- current->comm, current->pid, ss->name);
- if (!strcmp(ss->name, "memory"))
- pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
- ss->warned_broken_hierarchy = true;
- }
-
- return css;
-
-err_list_del:
- list_del_rcu(&css->sibling);
-err_free_css:
- call_rcu(&css->rcu_head, css_free_rcu_fn);
- return ERR_PTR(err);
-}
-
-static struct cgroup *cgroup_create(struct cgroup *parent)
-{
- struct cgroup_root *root = parent->root;
- struct cgroup *cgrp, *tcgrp;
- int level = parent->level + 1;
- int ret;
-
- /* allocate the cgroup and its ID, 0 is reserved for the root */
- cgrp = kzalloc(sizeof(*cgrp) +
- sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL);
- if (!cgrp)
- return ERR_PTR(-ENOMEM);
-
- ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
- if (ret)
- goto out_free_cgrp;
-
- /*
- * Temporarily set the pointer to NULL, so idr_find() won't return
- * a half-baked cgroup.
- */
- cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL);
- if (cgrp->id < 0) {
- ret = -ENOMEM;
- goto out_cancel_ref;
- }
-
- init_cgroup_housekeeping(cgrp);
-
- cgrp->self.parent = &parent->self;
- cgrp->root = root;
- cgrp->level = level;
-
- for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp))
- cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;
-
- if (notify_on_release(parent))
- set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
-
- if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
- set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
-
- cgrp->self.serial_nr = css_serial_nr_next++;
-
- /* allocation complete, commit to creation */
- list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
- atomic_inc(&root->nr_cgrps);
- cgroup_get(parent);
-
- /*
- * @cgrp is now fully operational. If something fails after this
- * point, it'll be released via the normal destruction path.
- */
- cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
-
- /*
- * On the default hierarchy, a child doesn't automatically inherit
- * subtree_control from the parent. Each is configured manually.
- */
- if (!cgroup_on_dfl(cgrp))
- cgrp->subtree_control = cgroup_control(cgrp);
-
- if (parent)
- cgroup_bpf_inherit(cgrp, parent);
-
- cgroup_propagate_control(cgrp);
-
- /* @cgrp doesn't have dir yet so the following will only create csses */
- ret = cgroup_apply_control_enable(cgrp);
- if (ret)
- goto out_destroy;
-
- return cgrp;
-
-out_cancel_ref:
- percpu_ref_exit(&cgrp->self.refcnt);
-out_free_cgrp:
- kfree(cgrp);
- return ERR_PTR(ret);
-out_destroy:
- cgroup_destroy_locked(cgrp);
- return ERR_PTR(ret);
-}
-
-static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
- umode_t mode)
-{
- struct cgroup *parent, *cgrp;
- struct kernfs_node *kn;
- int ret;
-
- /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
- if (strchr(name, '\n'))
- return -EINVAL;
-
- parent = cgroup_kn_lock_live(parent_kn, false);
- if (!parent)
- return -ENODEV;
-
- cgrp = cgroup_create(parent);
- if (IS_ERR(cgrp)) {
- ret = PTR_ERR(cgrp);
- goto out_unlock;
- }
-
- /* create the directory */
- kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
- if (IS_ERR(kn)) {
- ret = PTR_ERR(kn);
- goto out_destroy;
- }
- cgrp->kn = kn;
-
- /*
- * This extra ref will be put in cgroup_free_fn() and guarantees
- * that @cgrp->kn is always accessible.
- */
- kernfs_get(kn);
-
- ret = cgroup_kn_set_ugid(kn);
- if (ret)
- goto out_destroy;
-
- ret = css_populate_dir(&cgrp->self);
- if (ret)
- goto out_destroy;
-
- ret = cgroup_apply_control_enable(cgrp);
- if (ret)
- goto out_destroy;
-
- trace_cgroup_mkdir(cgrp);
-
- /* let's create and online css's */
- kernfs_activate(kn);
-
- ret = 0;
- goto out_unlock;
-
-out_destroy:
- cgroup_destroy_locked(cgrp);
-out_unlock:
- cgroup_kn_unlock(parent_kn);
- return ret;
-}
-
-/*
- * This is called when the refcnt of a css is confirmed to be killed.
- * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
- * initate destruction and put the css ref from kill_css().
- */
-static void css_killed_work_fn(struct work_struct *work)
-{
- struct cgroup_subsys_state *css =
- container_of(work, struct cgroup_subsys_state, destroy_work);
-
- mutex_lock(&cgroup_mutex);
-
- do {
- offline_css(css);
- css_put(css);
- /* @css can't go away while we're holding cgroup_mutex */
- css = css->parent;
- } while (css && atomic_dec_and_test(&css->online_cnt));
-
- mutex_unlock(&cgroup_mutex);
-}
-
-/* css kill confirmation processing requires process context, bounce */
-static void css_killed_ref_fn(struct percpu_ref *ref)
-{
- struct cgroup_subsys_state *css =
- container_of(ref, struct cgroup_subsys_state, refcnt);
-
- if (atomic_dec_and_test(&css->online_cnt)) {
- INIT_WORK(&css->destroy_work, css_killed_work_fn);
- queue_work(cgroup_destroy_wq, &css->destroy_work);
- }
-}
-
-/**
- * kill_css - destroy a css
- * @css: css to destroy
- *
- * This function initiates destruction of @css by removing cgroup interface
- * files and putting its base reference. ->css_offline() will be invoked
- * asynchronously once css_tryget_online() is guaranteed to fail and when
- * the reference count reaches zero, @css will be released.
- */
-static void kill_css(struct cgroup_subsys_state *css)
-{
- lockdep_assert_held(&cgroup_mutex);
-
- /*
- * This must happen before css is disassociated with its cgroup.
- * See seq_css() for details.
- */
- css_clear_dir(css);
-
- /*
- * Killing would put the base ref, but we need to keep it alive
- * until after ->css_offline().
- */
- css_get(css);
-
- /*
- * cgroup core guarantees that, by the time ->css_offline() is
- * invoked, no new css reference will be given out via
- * css_tryget_online(). We can't simply call percpu_ref_kill() and
- * proceed to offlining css's because percpu_ref_kill() doesn't
- * guarantee that the ref is seen as killed on all CPUs on return.
- *
- * Use percpu_ref_kill_and_confirm() to get notifications as each
- * css is confirmed to be seen as killed on all CPUs.
- */
- percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
-}
-
-/**
- * cgroup_destroy_locked - the first stage of cgroup destruction
- * @cgrp: cgroup to be destroyed
- *
- * css's make use of percpu refcnts whose killing latency shouldn't be
- * exposed to userland and are RCU protected. Also, cgroup core needs to
- * guarantee that css_tryget_online() won't succeed by the time
- * ->css_offline() is invoked. To satisfy all the requirements,
- * destruction is implemented in the following two steps.
- *
- * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
- * userland visible parts and start killing the percpu refcnts of
- * css's. Set up so that the next stage will be kicked off once all
- * the percpu refcnts are confirmed to be killed.
- *
- * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
- * rest of destruction. Once all cgroup references are gone, the
- * cgroup is RCU-freed.
- *
- * This function implements s1. After this step, @cgrp is gone as far as
- * the userland is concerned and a new cgroup with the same name may be
- * created. As cgroup doesn't care about the names internally, this
- * doesn't cause any problem.
- */
-static int cgroup_destroy_locked(struct cgroup *cgrp)
- __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
-{
- struct cgroup_subsys_state *css;
- struct cgrp_cset_link *link;
- int ssid;
-
- lockdep_assert_held(&cgroup_mutex);
-
- /*
- * Only migration can raise populated from zero and we're already
- * holding cgroup_mutex.
- */
- if (cgroup_is_populated(cgrp))
- return -EBUSY;
-
- /*
- * Make sure there's no live children. We can't test emptiness of
- * ->self.children as dead children linger on it while being
- * drained; otherwise, "rmdir parent/child parent" may fail.
- */
- if (css_has_online_children(&cgrp->self))
- return -EBUSY;
-
- /*
- * Mark @cgrp and the associated csets dead. The former prevents
- * further task migration and child creation by disabling
- * cgroup_lock_live_group(). The latter makes the csets ignored by
- * the migration path.
- */
- cgrp->self.flags &= ~CSS_ONLINE;
-
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(link, &cgrp->cset_links, cset_link)
- link->cset->dead = true;
- spin_unlock_irq(&css_set_lock);
-
- /* initiate massacre of all css's */
- for_each_css(css, ssid, cgrp)
- kill_css(css);
-
- /*
- * Remove @cgrp directory along with the base files. @cgrp has an
- * extra ref on its kn.
- */
- kernfs_remove(cgrp->kn);
-
- check_for_release(cgroup_parent(cgrp));
-
- /* put the base reference */
- percpu_ref_kill(&cgrp->self.refcnt);
-
- return 0;
-};
-
-static int cgroup_rmdir(struct kernfs_node *kn)
-{
- struct cgroup *cgrp;
- int ret = 0;
-
- cgrp = cgroup_kn_lock_live(kn, false);
- if (!cgrp)
- return 0;
-
- ret = cgroup_destroy_locked(cgrp);
-
- if (!ret)
- trace_cgroup_rmdir(cgrp);
-
- cgroup_kn_unlock(kn);
- return ret;
-}
-
-static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
- .remount_fs = cgroup_remount,
- .show_options = cgroup_show_options,
- .mkdir = cgroup_mkdir,
- .rmdir = cgroup_rmdir,
- .rename = cgroup_rename,
- .show_path = cgroup_show_path,
-};
-
-static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
-{
- struct cgroup_subsys_state *css;
-
- pr_debug("Initializing cgroup subsys %s\n", ss->name);
-
- mutex_lock(&cgroup_mutex);
-
- idr_init(&ss->css_idr);
- INIT_LIST_HEAD(&ss->cfts);
-
- /* Create the root cgroup state for this subsystem */
- ss->root = &cgrp_dfl_root;
- css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
- /* We don't handle early failures gracefully */
- BUG_ON(IS_ERR(css));
- init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
-
- /*
- * Root csses are never destroyed and we can't initialize
- * percpu_ref during early init. Disable refcnting.
- */
- css->flags |= CSS_NO_REF;
-
- if (early) {
- /* allocation can't be done safely during early init */
- css->id = 1;
- } else {
- css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
- BUG_ON(css->id < 0);
- }
-
- /* Update the init_css_set to contain a subsys
- * pointer to this state - since the subsystem is
- * newly registered, all tasks and hence the
- * init_css_set is in the subsystem's root cgroup. */
- init_css_set.subsys[ss->id] = css;
-
- have_fork_callback |= (bool)ss->fork << ss->id;
- have_exit_callback |= (bool)ss->exit << ss->id;
- have_free_callback |= (bool)ss->free << ss->id;
- have_canfork_callback |= (bool)ss->can_fork << ss->id;
-
- /* At system boot, before all subsystems have been
- * registered, no tasks have been forked, so we don't
- * need to invoke fork callbacks here. */
- BUG_ON(!list_empty(&init_task.tasks));
-
- BUG_ON(online_css(css));
-
- mutex_unlock(&cgroup_mutex);
-}
-
-/**
- * cgroup_init_early - cgroup initialization at system boot
- *
- * Initialize cgroups at system boot, and initialize any
- * subsystems that request early init.
- */
-int __init cgroup_init_early(void)
-{
- static struct cgroup_sb_opts __initdata opts;
- struct cgroup_subsys *ss;
- int i;
-
- init_cgroup_root(&cgrp_dfl_root, &opts);
- cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
-
- RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
-
- for_each_subsys(ss, i) {
- WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
- "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
- i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
- ss->id, ss->name);
- WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
- "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
-
- ss->id = i;
- ss->name = cgroup_subsys_name[i];
- if (!ss->legacy_name)
- ss->legacy_name = cgroup_subsys_name[i];
-
- if (ss->early_init)
- cgroup_init_subsys(ss, true);
- }
- return 0;
-}
-
-static u16 cgroup_disable_mask __initdata;
-
-/**
- * cgroup_init - cgroup initialization
- *
- * Register cgroup filesystem and /proc file, and initialize
- * any subsystems that didn't request early init.
- */
-int __init cgroup_init(void)
-{
- struct cgroup_subsys *ss;
- int ssid;
-
- BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
- BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
- BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
- BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
-
- /*
- * The latency of the synchronize_sched() is too high for cgroups,
- * avoid it at the cost of forcing all readers into the slow path.
- */
- rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss);
-
- get_user_ns(init_cgroup_ns.user_ns);
-
- mutex_lock(&cgroup_mutex);
-
- /*
- * Add init_css_set to the hash table so that dfl_root can link to
- * it during init.
- */
- hash_add(css_set_table, &init_css_set.hlist,
- css_set_hash(init_css_set.subsys));
-
- BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
-
- mutex_unlock(&cgroup_mutex);
-
- for_each_subsys(ss, ssid) {
- if (ss->early_init) {
- struct cgroup_subsys_state *css =
- init_css_set.subsys[ss->id];
-
- css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
- GFP_KERNEL);
- BUG_ON(css->id < 0);
- } else {
- cgroup_init_subsys(ss, false);
- }
-
- list_add_tail(&init_css_set.e_cset_node[ssid],
- &cgrp_dfl_root.cgrp.e_csets[ssid]);
-
- /*
- * Setting dfl_root subsys_mask needs to consider the
- * disabled flag and cftype registration needs kmalloc,
- * both of which aren't available during early_init.
- */
- if (cgroup_disable_mask & (1 << ssid)) {
- static_branch_disable(cgroup_subsys_enabled_key[ssid]);
- printk(KERN_INFO "Disabling %s control group subsystem\n",
- ss->name);
- continue;
- }
-
- if (cgroup_ssid_no_v1(ssid))
- printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n",
- ss->name);
-
- cgrp_dfl_root.subsys_mask |= 1 << ss->id;
-
- if (ss->implicit_on_dfl)
- cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
- else if (!ss->dfl_cftypes)
- cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
-
- if (ss->dfl_cftypes == ss->legacy_cftypes) {
- WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
- } else {
- WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
- WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
- }
-
- if (ss->bind)
- ss->bind(init_css_set.subsys[ssid]);
- }
-
- /* init_css_set.subsys[] has been updated, re-hash */
- hash_del(&init_css_set.hlist);
- hash_add(css_set_table, &init_css_set.hlist,
- css_set_hash(init_css_set.subsys));
-
- WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
- WARN_ON(register_filesystem(&cgroup_fs_type));
- WARN_ON(register_filesystem(&cgroup2_fs_type));
- WARN_ON(!proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations));
-
- return 0;
-}
-
-static int __init cgroup_wq_init(void)
-{
- /*
- * There isn't much point in executing destruction path in
- * parallel. Good chunk is serialized with cgroup_mutex anyway.
- * Use 1 for @max_active.
- *
- * We would prefer to do this in cgroup_init() above, but that
- * is called before init_workqueues(): so leave this until after.
- */
- cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
- BUG_ON(!cgroup_destroy_wq);
-
- /*
- * Used to destroy pidlists and separate to serve as flush domain.
- * Cap @max_active to 1 too.
- */
- cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
- 0, 1);
- BUG_ON(!cgroup_pidlist_destroy_wq);
-
- return 0;
-}
-core_initcall(cgroup_wq_init);
-
-/*
- * proc_cgroup_show()
- * - Print task's cgroup paths into seq_file, one line for each hierarchy
- * - Used for /proc/<pid>/cgroup.
- */
-int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk)
-{
- char *buf;
- int retval;
- struct cgroup_root *root;
-
- retval = -ENOMEM;
- buf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!buf)
- goto out;
-
- mutex_lock(&cgroup_mutex);
- spin_lock_irq(&css_set_lock);
-
- for_each_root(root) {
- struct cgroup_subsys *ss;
- struct cgroup *cgrp;
- int ssid, count = 0;
-
- if (root == &cgrp_dfl_root && !cgrp_dfl_visible)
- continue;
-
- seq_printf(m, "%d:", root->hierarchy_id);
- if (root != &cgrp_dfl_root)
- for_each_subsys(ss, ssid)
- if (root->subsys_mask & (1 << ssid))
- seq_printf(m, "%s%s", count++ ? "," : "",
- ss->legacy_name);
- if (strlen(root->name))
- seq_printf(m, "%sname=%s", count ? "," : "",
- root->name);
- seq_putc(m, ':');
-
- cgrp = task_cgroup_from_root(tsk, root);
-
- /*
- * On traditional hierarchies, all zombie tasks show up as
- * belonging to the root cgroup. On the default hierarchy,
- * while a zombie doesn't show up in "cgroup.procs" and
- * thus can't be migrated, its /proc/PID/cgroup keeps
- * reporting the cgroup it belonged to before exiting. If
- * the cgroup is removed before the zombie is reaped,
- * " (deleted)" is appended to the cgroup path.
- */
- if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
- retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
- current->nsproxy->cgroup_ns);
- if (retval >= PATH_MAX)
- retval = -ENAMETOOLONG;
- if (retval < 0)
- goto out_unlock;
-
- seq_puts(m, buf);
- } else {
- seq_puts(m, "/");
- }
-
- if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
- seq_puts(m, " (deleted)\n");
- else
- seq_putc(m, '\n');
- }
-
- retval = 0;
-out_unlock:
- spin_unlock_irq(&css_set_lock);
- mutex_unlock(&cgroup_mutex);
- kfree(buf);
-out:
- return retval;
-}
-
-/* Display information about each subsystem and each hierarchy */
-static int proc_cgroupstats_show(struct seq_file *m, void *v)
-{
- struct cgroup_subsys *ss;
- int i;
-
- seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
- /*
- * ideally we don't want subsystems moving around while we do this.
- * cgroup_mutex is also necessary to guarantee an atomic snapshot of
- * subsys/hierarchy state.
- */
- mutex_lock(&cgroup_mutex);
-
- for_each_subsys(ss, i)
- seq_printf(m, "%s\t%d\t%d\t%d\n",
- ss->legacy_name, ss->root->hierarchy_id,
- atomic_read(&ss->root->nr_cgrps),
- cgroup_ssid_enabled(i));
-
- mutex_unlock(&cgroup_mutex);
- return 0;
-}
-
-static int cgroupstats_open(struct inode *inode, struct file *file)
-{
- return single_open(file, proc_cgroupstats_show, NULL);
-}
-
-static const struct file_operations proc_cgroupstats_operations = {
- .open = cgroupstats_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = single_release,
-};
-
-/**
- * cgroup_fork - initialize cgroup related fields during copy_process()
- * @child: pointer to task_struct of forking parent process.
- *
- * A task is associated with the init_css_set until cgroup_post_fork()
- * attaches it to the parent's css_set. Empty cg_list indicates that
- * @child isn't holding reference to its css_set.
- */
-void cgroup_fork(struct task_struct *child)
-{
- RCU_INIT_POINTER(child->cgroups, &init_css_set);
- INIT_LIST_HEAD(&child->cg_list);
-}
-
-/**
- * cgroup_can_fork - called on a new task before the process is exposed
- * @child: the task in question.
- *
- * This calls the subsystem can_fork() callbacks. If the can_fork() callback
- * returns an error, the fork aborts with that error code. This allows for
- * a cgroup subsystem to conditionally allow or deny new forks.
- */
-int cgroup_can_fork(struct task_struct *child)
-{
- struct cgroup_subsys *ss;
- int i, j, ret;
-
- do_each_subsys_mask(ss, i, have_canfork_callback) {
- ret = ss->can_fork(child);
- if (ret)
- goto out_revert;
- } while_each_subsys_mask();
-
- return 0;
-
-out_revert:
- for_each_subsys(ss, j) {
- if (j >= i)
- break;
- if (ss->cancel_fork)
- ss->cancel_fork(child);
- }
-
- return ret;
-}
-
-/**
- * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
- * @child: the task in question
- *
- * This calls the cancel_fork() callbacks if a fork failed *after*
- * cgroup_can_fork() succeded.
- */
-void cgroup_cancel_fork(struct task_struct *child)
-{
- struct cgroup_subsys *ss;
- int i;
-
- for_each_subsys(ss, i)
- if (ss->cancel_fork)
- ss->cancel_fork(child);
-}
-
-/**
- * cgroup_post_fork - called on a new task after adding it to the task list
- * @child: the task in question
- *
- * Adds the task to the list running through its css_set if necessary and
- * call the subsystem fork() callbacks. Has to be after the task is
- * visible on the task list in case we race with the first call to
- * cgroup_task_iter_start() - to guarantee that the new task ends up on its
- * list.
- */
-void cgroup_post_fork(struct task_struct *child)
-{
- struct cgroup_subsys *ss;
- int i;
-
- /*
- * This may race against cgroup_enable_task_cg_lists(). As that
- * function sets use_task_css_set_links before grabbing
- * tasklist_lock and we just went through tasklist_lock to add
- * @child, it's guaranteed that either we see the set
- * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
- * @child during its iteration.
- *
- * If we won the race, @child is associated with %current's
- * css_set. Grabbing css_set_lock guarantees both that the
- * association is stable, and, on completion of the parent's
- * migration, @child is visible in the source of migration or
- * already in the destination cgroup. This guarantee is necessary
- * when implementing operations which need to migrate all tasks of
- * a cgroup to another.
- *
- * Note that if we lose to cgroup_enable_task_cg_lists(), @child
- * will remain in init_css_set. This is safe because all tasks are
- * in the init_css_set before cg_links is enabled and there's no
- * operation which transfers all tasks out of init_css_set.
- */
- if (use_task_css_set_links) {
- struct css_set *cset;
-
- spin_lock_irq(&css_set_lock);
- cset = task_css_set(current);
- if (list_empty(&child->cg_list)) {
- get_css_set(cset);
- css_set_move_task(child, NULL, cset, false);
- }
- spin_unlock_irq(&css_set_lock);
- }
-
- /*
- * Call ss->fork(). This must happen after @child is linked on
- * css_set; otherwise, @child might change state between ->fork()
- * and addition to css_set.
- */
- do_each_subsys_mask(ss, i, have_fork_callback) {
- ss->fork(child);
- } while_each_subsys_mask();
-}
-
-/**
- * cgroup_exit - detach cgroup from exiting task
- * @tsk: pointer to task_struct of exiting process
- *
- * Description: Detach cgroup from @tsk and release it.
- *
- * Note that cgroups marked notify_on_release force every task in
- * them to take the global cgroup_mutex mutex when exiting.
- * This could impact scaling on very large systems. Be reluctant to
- * use notify_on_release cgroups where very high task exit scaling
- * is required on large systems.
- *
- * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
- * call cgroup_exit() while the task is still competent to handle
- * notify_on_release(), then leave the task attached to the root cgroup in
- * each hierarchy for the remainder of its exit. No need to bother with
- * init_css_set refcnting. init_css_set never goes away and we can't race
- * with migration path - PF_EXITING is visible to migration path.
- */
-void cgroup_exit(struct task_struct *tsk)
-{
- struct cgroup_subsys *ss;
- struct css_set *cset;
- int i;
-
- /*
- * Unlink from @tsk from its css_set. As migration path can't race
- * with us, we can check css_set and cg_list without synchronization.
- */
- cset = task_css_set(tsk);
-
- if (!list_empty(&tsk->cg_list)) {
- spin_lock_irq(&css_set_lock);
- css_set_move_task(tsk, cset, NULL, false);
- spin_unlock_irq(&css_set_lock);
- } else {
- get_css_set(cset);
- }
-
- /* see cgroup_post_fork() for details */
- do_each_subsys_mask(ss, i, have_exit_callback) {
- ss->exit(tsk);
- } while_each_subsys_mask();
-}
-
-void cgroup_free(struct task_struct *task)
-{
- struct css_set *cset = task_css_set(task);
- struct cgroup_subsys *ss;
- int ssid;
-
- do_each_subsys_mask(ss, ssid, have_free_callback) {
- ss->free(task);
- } while_each_subsys_mask();
-
- put_css_set(cset);
-}
-
-static void check_for_release(struct cgroup *cgrp)
-{
- if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
- !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
- schedule_work(&cgrp->release_agent_work);
-}
-
-/*
- * Notify userspace when a cgroup is released, by running the
- * configured release agent with the name of the cgroup (path
- * relative to the root of cgroup file system) as the argument.
- *
- * Most likely, this user command will try to rmdir this cgroup.
- *
- * This races with the possibility that some other task will be
- * attached to this cgroup before it is removed, or that some other
- * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
- * The presumed 'rmdir' will fail quietly if this cgroup is no longer
- * unused, and this cgroup will be reprieved from its death sentence,
- * to continue to serve a useful existence. Next time it's released,
- * we will get notified again, if it still has 'notify_on_release' set.
- *
- * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
- * means only wait until the task is successfully execve()'d. The
- * separate release agent task is forked by call_usermodehelper(),
- * then control in this thread returns here, without waiting for the
- * release agent task. We don't bother to wait because the caller of
- * this routine has no use for the exit status of the release agent
- * task, so no sense holding our caller up for that.
- */
-static void cgroup_release_agent(struct work_struct *work)
-{
- struct cgroup *cgrp =
- container_of(work, struct cgroup, release_agent_work);
- char *pathbuf = NULL, *agentbuf = NULL;
- char *argv[3], *envp[3];
- int ret;
-
- mutex_lock(&cgroup_mutex);
-
- pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
- agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
- if (!pathbuf || !agentbuf)
- goto out;
-
- spin_lock_irq(&css_set_lock);
- ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
- spin_unlock_irq(&css_set_lock);
- if (ret < 0 || ret >= PATH_MAX)
- goto out;
-
- argv[0] = agentbuf;
- argv[1] = pathbuf;
- argv[2] = NULL;
-
- /* minimal command environment */
- envp[0] = "HOME=/";
- envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
- envp[2] = NULL;
-
- mutex_unlock(&cgroup_mutex);
- call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
- goto out_free;
-out:
- mutex_unlock(&cgroup_mutex);
-out_free:
- kfree(agentbuf);
- kfree(pathbuf);
-}
-
-static int __init cgroup_disable(char *str)
-{
- struct cgroup_subsys *ss;
- char *token;
- int i;
-
- while ((token = strsep(&str, ",")) != NULL) {
- if (!*token)
- continue;
-
- for_each_subsys(ss, i) {
- if (strcmp(token, ss->name) &&
- strcmp(token, ss->legacy_name))
- continue;
- cgroup_disable_mask |= 1 << i;
- }
- }
- return 1;
-}
-__setup("cgroup_disable=", cgroup_disable);
-
-static int __init cgroup_no_v1(char *str)
-{
- struct cgroup_subsys *ss;
- char *token;
- int i;
-
- while ((token = strsep(&str, ",")) != NULL) {
- if (!*token)
- continue;
-
- if (!strcmp(token, "all")) {
- cgroup_no_v1_mask = U16_MAX;
- break;
- }
-
- for_each_subsys(ss, i) {
- if (strcmp(token, ss->name) &&
- strcmp(token, ss->legacy_name))
- continue;
-
- cgroup_no_v1_mask |= 1 << i;
- }
- }
- return 1;
-}
-__setup("cgroup_no_v1=", cgroup_no_v1);
-
-/**
- * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
- * @dentry: directory dentry of interest
- * @ss: subsystem of interest
- *
- * If @dentry is a directory for a cgroup which has @ss enabled on it, try
- * to get the corresponding css and return it. If such css doesn't exist
- * or can't be pinned, an ERR_PTR value is returned.
- */
-struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
- struct cgroup_subsys *ss)
-{
- struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
- struct file_system_type *s_type = dentry->d_sb->s_type;
- struct cgroup_subsys_state *css = NULL;
- struct cgroup *cgrp;
-
- /* is @dentry a cgroup dir? */
- if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) ||
- !kn || kernfs_type(kn) != KERNFS_DIR)
- return ERR_PTR(-EBADF);
-
- rcu_read_lock();
-
- /*
- * This path doesn't originate from kernfs and @kn could already
- * have been or be removed at any point. @kn->priv is RCU
- * protected for this access. See css_release_work_fn() for details.
- */
- cgrp = rcu_dereference(kn->priv);
- if (cgrp)
- css = cgroup_css(cgrp, ss);
-
- if (!css || !css_tryget_online(css))
- css = ERR_PTR(-ENOENT);
-
- rcu_read_unlock();
- return css;
-}
-
-/**
- * css_from_id - lookup css by id
- * @id: the cgroup id
- * @ss: cgroup subsys to be looked into
- *
- * Returns the css if there's valid one with @id, otherwise returns NULL.
- * Should be called under rcu_read_lock().
- */
-struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
-{
- WARN_ON_ONCE(!rcu_read_lock_held());
- return idr_find(&ss->css_idr, id);
-}
-
-/**
- * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
- * @path: path on the default hierarchy
- *
- * Find the cgroup at @path on the default hierarchy, increment its
- * reference count and return it. Returns pointer to the found cgroup on
- * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
- * if @path points to a non-directory.
- */
-struct cgroup *cgroup_get_from_path(const char *path)
-{
- struct kernfs_node *kn;
- struct cgroup *cgrp;
-
- mutex_lock(&cgroup_mutex);
-
- kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path);
- if (kn) {
- if (kernfs_type(kn) == KERNFS_DIR) {
- cgrp = kn->priv;
- cgroup_get(cgrp);
- } else {
- cgrp = ERR_PTR(-ENOTDIR);
- }
- kernfs_put(kn);
- } else {
- cgrp = ERR_PTR(-ENOENT);
- }
-
- mutex_unlock(&cgroup_mutex);
- return cgrp;
-}
-EXPORT_SYMBOL_GPL(cgroup_get_from_path);
-
-/**
- * cgroup_get_from_fd - get a cgroup pointer from a fd
- * @fd: fd obtained by open(cgroup2_dir)
- *
- * Find the cgroup from a fd which should be obtained
- * by opening a cgroup directory. Returns a pointer to the
- * cgroup on success. ERR_PTR is returned if the cgroup
- * cannot be found.
- */
-struct cgroup *cgroup_get_from_fd(int fd)
-{
- struct cgroup_subsys_state *css;
- struct cgroup *cgrp;
- struct file *f;
-
- f = fget_raw(fd);
- if (!f)
- return ERR_PTR(-EBADF);
-
- css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
- fput(f);
- if (IS_ERR(css))
- return ERR_CAST(css);
-
- cgrp = css->cgroup;
- if (!cgroup_on_dfl(cgrp)) {
- cgroup_put(cgrp);
- return ERR_PTR(-EBADF);
- }
-
- return cgrp;
-}
-EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
-
-/*
- * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
- * definition in cgroup-defs.h.
- */
-#ifdef CONFIG_SOCK_CGROUP_DATA
-
-#if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
-
-DEFINE_SPINLOCK(cgroup_sk_update_lock);
-static bool cgroup_sk_alloc_disabled __read_mostly;
-
-void cgroup_sk_alloc_disable(void)
-{
- if (cgroup_sk_alloc_disabled)
- return;
- pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
- cgroup_sk_alloc_disabled = true;
-}
-
-#else
-
-#define cgroup_sk_alloc_disabled false
-
-#endif
-
-void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
-{
- if (cgroup_sk_alloc_disabled)
- return;
-
- /* Socket clone path */
- if (skcd->val) {
- cgroup_get(sock_cgroup_ptr(skcd));
- return;
- }
-
- rcu_read_lock();
-
- while (true) {
- struct css_set *cset;
-
- cset = task_css_set(current);
- if (likely(cgroup_tryget(cset->dfl_cgrp))) {
- skcd->val = (unsigned long)cset->dfl_cgrp;
- break;
- }
- cpu_relax();
- }
-
- rcu_read_unlock();
-}
-
-void cgroup_sk_free(struct sock_cgroup_data *skcd)
-{
- cgroup_put(sock_cgroup_ptr(skcd));
-}
-
-#endif /* CONFIG_SOCK_CGROUP_DATA */
-
-/* cgroup namespaces */
-
-static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
-{
- return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
-}
-
-static void dec_cgroup_namespaces(struct ucounts *ucounts)
-{
- dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
-}
-
-static struct cgroup_namespace *alloc_cgroup_ns(void)
-{
- struct cgroup_namespace *new_ns;
- int ret;
-
- new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
- if (!new_ns)
- return ERR_PTR(-ENOMEM);
- ret = ns_alloc_inum(&new_ns->ns);
- if (ret) {
- kfree(new_ns);
- return ERR_PTR(ret);
- }
- atomic_set(&new_ns->count, 1);
- new_ns->ns.ops = &cgroupns_operations;
- return new_ns;
-}
-
-void free_cgroup_ns(struct cgroup_namespace *ns)
-{
- put_css_set(ns->root_cset);
- dec_cgroup_namespaces(ns->ucounts);
- put_user_ns(ns->user_ns);
- ns_free_inum(&ns->ns);
- kfree(ns);
-}
-EXPORT_SYMBOL(free_cgroup_ns);
-
-struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
- struct user_namespace *user_ns,
- struct cgroup_namespace *old_ns)
-{
- struct cgroup_namespace *new_ns;
- struct ucounts *ucounts;
- struct css_set *cset;
-
- BUG_ON(!old_ns);
-
- if (!(flags & CLONE_NEWCGROUP)) {
- get_cgroup_ns(old_ns);
- return old_ns;
- }
-
- /* Allow only sysadmin to create cgroup namespace. */
- if (!ns_capable(user_ns, CAP_SYS_ADMIN))
- return ERR_PTR(-EPERM);
-
- ucounts = inc_cgroup_namespaces(user_ns);
- if (!ucounts)
- return ERR_PTR(-ENOSPC);
-
- /* It is not safe to take cgroup_mutex here */
- spin_lock_irq(&css_set_lock);
- cset = task_css_set(current);
- get_css_set(cset);
- spin_unlock_irq(&css_set_lock);
-
- new_ns = alloc_cgroup_ns();
- if (IS_ERR(new_ns)) {
- put_css_set(cset);
- dec_cgroup_namespaces(ucounts);
- return new_ns;
- }
-
- new_ns->user_ns = get_user_ns(user_ns);
- new_ns->ucounts = ucounts;
- new_ns->root_cset = cset;
-
- return new_ns;
-}
-
-static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
-{
- return container_of(ns, struct cgroup_namespace, ns);
-}
-
-static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns)
-{
- struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
-
- if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
- !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
- return -EPERM;
-
- /* Don't need to do anything if we are attaching to our own cgroupns. */
- if (cgroup_ns == nsproxy->cgroup_ns)
- return 0;
-
- get_cgroup_ns(cgroup_ns);
- put_cgroup_ns(nsproxy->cgroup_ns);
- nsproxy->cgroup_ns = cgroup_ns;
-
- return 0;
-}
-
-static struct ns_common *cgroupns_get(struct task_struct *task)
-{
- struct cgroup_namespace *ns = NULL;
- struct nsproxy *nsproxy;
-
- task_lock(task);
- nsproxy = task->nsproxy;
- if (nsproxy) {
- ns = nsproxy->cgroup_ns;
- get_cgroup_ns(ns);
- }
- task_unlock(task);
-
- return ns ? &ns->ns : NULL;
-}
-
-static void cgroupns_put(struct ns_common *ns)
-{
- put_cgroup_ns(to_cg_ns(ns));
-}
-
-static struct user_namespace *cgroupns_owner(struct ns_common *ns)
-{
- return to_cg_ns(ns)->user_ns;
-}
-
-const struct proc_ns_operations cgroupns_operations = {
- .name = "cgroup",
- .type = CLONE_NEWCGROUP,
- .get = cgroupns_get,
- .put = cgroupns_put,
- .install = cgroupns_install,
- .owner = cgroupns_owner,
-};
-
-static __init int cgroup_namespaces_init(void)
-{
- return 0;
-}
-subsys_initcall(cgroup_namespaces_init);
-
-#ifdef CONFIG_CGROUP_BPF
-void cgroup_bpf_update(struct cgroup *cgrp,
- struct bpf_prog *prog,
- enum bpf_attach_type type)
-{
- struct cgroup *parent = cgroup_parent(cgrp);
-
- mutex_lock(&cgroup_mutex);
- __cgroup_bpf_update(cgrp, parent, prog, type);
- mutex_unlock(&cgroup_mutex);
-}
-#endif /* CONFIG_CGROUP_BPF */
-
-#ifdef CONFIG_CGROUP_DEBUG
-static struct cgroup_subsys_state *
-debug_css_alloc(struct cgroup_subsys_state *parent_css)
-{
- struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
-
- if (!css)
- return ERR_PTR(-ENOMEM);
-
- return css;
-}
-
-static void debug_css_free(struct cgroup_subsys_state *css)
-{
- kfree(css);
-}
-
-static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- return cgroup_task_count(css->cgroup);
-}
-
-static u64 current_css_set_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- return (u64)(unsigned long)current->cgroups;
-}
-
-static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- u64 count;
-
- rcu_read_lock();
- count = atomic_read(&task_css_set(current)->refcount);
- rcu_read_unlock();
- return count;
-}
-
-static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
-{
- struct cgrp_cset_link *link;
- struct css_set *cset;
- char *name_buf;
-
- name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
- if (!name_buf)
- return -ENOMEM;
-
- spin_lock_irq(&css_set_lock);
- rcu_read_lock();
- cset = rcu_dereference(current->cgroups);
- list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
- struct cgroup *c = link->cgrp;
-
- cgroup_name(c, name_buf, NAME_MAX + 1);
- seq_printf(seq, "Root %d group %s\n",
- c->root->hierarchy_id, name_buf);
- }
- rcu_read_unlock();
- spin_unlock_irq(&css_set_lock);
- kfree(name_buf);
- return 0;
-}
-
-#define MAX_TASKS_SHOWN_PER_CSS 25
-static int cgroup_css_links_read(struct seq_file *seq, void *v)
-{
- struct cgroup_subsys_state *css = seq_css(seq);
- struct cgrp_cset_link *link;
-
- spin_lock_irq(&css_set_lock);
- list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
- struct css_set *cset = link->cset;
- struct task_struct *task;
- int count = 0;
-
- seq_printf(seq, "css_set %p\n", cset);
-
- list_for_each_entry(task, &cset->tasks, cg_list) {
- if (count++ > MAX_TASKS_SHOWN_PER_CSS)
- goto overflow;
- seq_printf(seq, " task %d\n", task_pid_vnr(task));
- }
-
- list_for_each_entry(task, &cset->mg_tasks, cg_list) {
- if (count++ > MAX_TASKS_SHOWN_PER_CSS)
- goto overflow;
- seq_printf(seq, " task %d\n", task_pid_vnr(task));
- }
- continue;
- overflow:
- seq_puts(seq, " ...\n");
- }
- spin_unlock_irq(&css_set_lock);
- return 0;
-}
-
-static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
-{
- return (!cgroup_is_populated(css->cgroup) &&
- !css_has_online_children(&css->cgroup->self));
-}
-
-static struct cftype debug_files[] = {
- {
- .name = "taskcount",
- .read_u64 = debug_taskcount_read,
- },
-
- {
- .name = "current_css_set",
- .read_u64 = current_css_set_read,
- },
-
- {
- .name = "current_css_set_refcount",
- .read_u64 = current_css_set_refcount_read,
- },
-
- {
- .name = "current_css_set_cg_links",
- .seq_show = current_css_set_cg_links_read,
- },
-
- {
- .name = "cgroup_css_links",
- .seq_show = cgroup_css_links_read,
- },
-
- {
- .name = "releasable",
- .read_u64 = releasable_read,
- },
-
- { } /* terminate */
-};
-
-struct cgroup_subsys debug_cgrp_subsys = {
- .css_alloc = debug_css_alloc,
- .css_free = debug_css_free,
- .legacy_cftypes = debug_files,
-};
-#endif /* CONFIG_CGROUP_DEBUG */
--- /dev/null
+obj-y := cgroup.o
+
+obj-$(CONFIG_CGROUP_FREEZER) += freezer.o
+obj-$(CONFIG_CGROUP_PIDS) += pids.o
+obj-$(CONFIG_CPUSETS) += cpuset.o
--- /dev/null
+/*
+ * Generic process-grouping system.
+ *
+ * Based originally on the cpuset system, extracted by Paul Menage
+ * Copyright (C) 2006 Google, Inc
+ *
+ * Notifications support
+ * Copyright (C) 2009 Nokia Corporation
+ * Author: Kirill A. Shutemov
+ *
+ * Copyright notices from the original cpuset code:
+ * --------------------------------------------------
+ * Copyright (C) 2003 BULL SA.
+ * Copyright (C) 2004-2006 Silicon Graphics, Inc.
+ *
+ * Portions derived from Patrick Mochel's sysfs code.
+ * sysfs is Copyright (c) 2001-3 Patrick Mochel
+ *
+ * 2003-10-10 Written by Simon Derr.
+ * 2003-10-22 Updates by Stephen Hemminger.
+ * 2004 May-July Rework by Paul Jackson.
+ * ---------------------------------------------------
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cgroup.h>
+#include <linux/cred.h>
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/init_task.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/magic.h>
+#include <linux/mm.h>
+#include <linux/mutex.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/proc_fs.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/percpu-rwsem.h>
+#include <linux/string.h>
+#include <linux/sort.h>
+#include <linux/kmod.h>
+#include <linux/delayacct.h>
+#include <linux/cgroupstats.h>
+#include <linux/hashtable.h>
+#include <linux/pid_namespace.h>
+#include <linux/idr.h>
+#include <linux/vmalloc.h> /* TODO: replace with more sophisticated array */
+#include <linux/kthread.h>
+#include <linux/delay.h>
+#include <linux/atomic.h>
+#include <linux/cpuset.h>
+#include <linux/proc_ns.h>
+#include <linux/nsproxy.h>
+#include <linux/file.h>
+#include <net/sock.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/cgroup.h>
+
+/*
+ * pidlists linger the following amount before being destroyed. The goal
+ * is avoiding frequent destruction in the middle of consecutive read calls
+ * Expiring in the middle is a performance problem not a correctness one.
+ * 1 sec should be enough.
+ */
+#define CGROUP_PIDLIST_DESTROY_DELAY HZ
+
+#define CGROUP_FILE_NAME_MAX (MAX_CGROUP_TYPE_NAMELEN + \
+ MAX_CFTYPE_NAME + 2)
+
+/*
+ * cgroup_mutex is the master lock. Any modification to cgroup or its
+ * hierarchy must be performed while holding it.
+ *
+ * css_set_lock protects task->cgroups pointer, the list of css_set
+ * objects, and the chain of tasks off each css_set.
+ *
+ * These locks are exported if CONFIG_PROVE_RCU so that accessors in
+ * cgroup.h can use them for lockdep annotations.
+ */
+#ifdef CONFIG_PROVE_RCU
+DEFINE_MUTEX(cgroup_mutex);
+DEFINE_SPINLOCK(css_set_lock);
+EXPORT_SYMBOL_GPL(cgroup_mutex);
+EXPORT_SYMBOL_GPL(css_set_lock);
+#else
+static DEFINE_MUTEX(cgroup_mutex);
+static DEFINE_SPINLOCK(css_set_lock);
+#endif
+
+/*
+ * Protects cgroup_idr and css_idr so that IDs can be released without
+ * grabbing cgroup_mutex.
+ */
+static DEFINE_SPINLOCK(cgroup_idr_lock);
+
+/*
+ * Protects cgroup_file->kn for !self csses. It synchronizes notifications
+ * against file removal/re-creation across css hiding.
+ */
+static DEFINE_SPINLOCK(cgroup_file_kn_lock);
+
+/*
+ * Protects cgroup_subsys->release_agent_path. Modifying it also requires
+ * cgroup_mutex. Reading requires either cgroup_mutex or this spinlock.
+ */
+static DEFINE_SPINLOCK(release_agent_path_lock);
+
+struct percpu_rw_semaphore cgroup_threadgroup_rwsem;
+
+#define cgroup_assert_mutex_or_rcu_locked() \
+ RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
+ !lockdep_is_held(&cgroup_mutex), \
+ "cgroup_mutex or RCU read lock required");
+
+/*
+ * cgroup destruction makes heavy use of work items and there can be a lot
+ * of concurrent destructions. Use a separate workqueue so that cgroup
+ * destruction work items don't end up filling up max_active of system_wq
+ * which may lead to deadlock.
+ */
+static struct workqueue_struct *cgroup_destroy_wq;
+
+/*
+ * pidlist destructions need to be flushed on cgroup destruction. Use a
+ * separate workqueue as flush domain.
+ */
+static struct workqueue_struct *cgroup_pidlist_destroy_wq;
+
+/* generate an array of cgroup subsystem pointers */
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys,
+static struct cgroup_subsys *cgroup_subsys[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+/* array of cgroup subsystem names */
+#define SUBSYS(_x) [_x ## _cgrp_id] = #_x,
+static const char *cgroup_subsys_name[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+/* array of static_keys for cgroup_subsys_enabled() and cgroup_subsys_on_dfl() */
+#define SUBSYS(_x) \
+ DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_enabled_key); \
+ DEFINE_STATIC_KEY_TRUE(_x ## _cgrp_subsys_on_dfl_key); \
+ EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_enabled_key); \
+ EXPORT_SYMBOL_GPL(_x ## _cgrp_subsys_on_dfl_key);
+#include <linux/cgroup_subsys.h>
+#undef SUBSYS
+
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_enabled_key,
+static struct static_key_true *cgroup_subsys_enabled_key[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+#define SUBSYS(_x) [_x ## _cgrp_id] = &_x ## _cgrp_subsys_on_dfl_key,
+static struct static_key_true *cgroup_subsys_on_dfl_key[] = {
+#include <linux/cgroup_subsys.h>
+};
+#undef SUBSYS
+
+/*
+ * The default hierarchy, reserved for the subsystems that are otherwise
+ * unattached - it never has more than a single cgroup, and all tasks are
+ * part of that cgroup.
+ */
+struct cgroup_root cgrp_dfl_root;
+EXPORT_SYMBOL_GPL(cgrp_dfl_root);
+
+/*
+ * The default hierarchy always exists but is hidden until mounted for the
+ * first time. This is for backward compatibility.
+ */
+static bool cgrp_dfl_visible;
+
+/* Controllers blocked by the commandline in v1 */
+static u16 cgroup_no_v1_mask;
+
+/* some controllers are not supported in the default hierarchy */
+static u16 cgrp_dfl_inhibit_ss_mask;
+
+/* some controllers are implicitly enabled on the default hierarchy */
+static unsigned long cgrp_dfl_implicit_ss_mask;
+
+/* The list of hierarchy roots */
+
+static LIST_HEAD(cgroup_roots);
+static int cgroup_root_count;
+
+/* hierarchy ID allocation and mapping, protected by cgroup_mutex */
+static DEFINE_IDR(cgroup_hierarchy_idr);
+
+/*
+ * Assign a monotonically increasing serial number to csses. It guarantees
+ * cgroups with bigger numbers are newer than those with smaller numbers.
+ * Also, as csses are always appended to the parent's ->children list, it
+ * guarantees that sibling csses are always sorted in the ascending serial
+ * number order on the list. Protected by cgroup_mutex.
+ */
+static u64 css_serial_nr_next = 1;
+
+/*
+ * These bitmask flags indicate whether tasks in the fork and exit paths have
+ * fork/exit handlers to call. This avoids us having to do extra work in the
+ * fork/exit path to check which subsystems have fork/exit callbacks.
+ */
+static u16 have_fork_callback __read_mostly;
+static u16 have_exit_callback __read_mostly;
+static u16 have_free_callback __read_mostly;
+
+/* cgroup namespace for init task */
+struct cgroup_namespace init_cgroup_ns = {
+ .count = { .counter = 2, },
+ .user_ns = &init_user_ns,
+ .ns.ops = &cgroupns_operations,
+ .ns.inum = PROC_CGROUP_INIT_INO,
+ .root_cset = &init_css_set,
+};
+
+/* Ditto for the can_fork callback. */
+static u16 have_canfork_callback __read_mostly;
+
+static struct file_system_type cgroup2_fs_type;
+static struct cftype cgroup_dfl_base_files[];
+static struct cftype cgroup_legacy_base_files[];
+
+static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);
+static void cgroup_lock_and_drain_offline(struct cgroup *cgrp);
+static int cgroup_apply_control(struct cgroup *cgrp);
+static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
+static void css_task_iter_advance(struct css_task_iter *it);
+static int cgroup_destroy_locked(struct cgroup *cgrp);
+static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
+ struct cgroup_subsys *ss);
+static void css_release(struct percpu_ref *ref);
+static void kill_css(struct cgroup_subsys_state *css);
+static int cgroup_addrm_files(struct cgroup_subsys_state *css,
+ struct cgroup *cgrp, struct cftype cfts[],
+ bool is_add);
+
+/**
+ * cgroup_ssid_enabled - cgroup subsys enabled test by subsys ID
+ * @ssid: subsys ID of interest
+ *
+ * cgroup_subsys_enabled() can only be used with literal subsys names which
+ * is fine for individual subsystems but unsuitable for cgroup core. This
+ * is slower static_key_enabled() based test indexed by @ssid.
+ */
+static bool cgroup_ssid_enabled(int ssid)
+{
+ if (CGROUP_SUBSYS_COUNT == 0)
+ return false;
+
+ return static_key_enabled(cgroup_subsys_enabled_key[ssid]);
+}
+
+static bool cgroup_ssid_no_v1(int ssid)
+{
+ return cgroup_no_v1_mask & (1 << ssid);
+}
+
+/**
+ * cgroup_on_dfl - test whether a cgroup is on the default hierarchy
+ * @cgrp: the cgroup of interest
+ *
+ * The default hierarchy is the v2 interface of cgroup and this function
+ * can be used to test whether a cgroup is on the default hierarchy for
+ * cases where a subsystem should behave differnetly depending on the
+ * interface version.
+ *
+ * The set of behaviors which change on the default hierarchy are still
+ * being determined and the mount option is prefixed with __DEVEL__.
+ *
+ * List of changed behaviors:
+ *
+ * - Mount options "noprefix", "xattr", "clone_children", "release_agent"
+ * and "name" are disallowed.
+ *
+ * - When mounting an existing superblock, mount options should match.
+ *
+ * - Remount is disallowed.
+ *
+ * - rename(2) is disallowed.
+ *
+ * - "tasks" is removed. Everything should be at process granularity. Use
+ * "cgroup.procs" instead.
+ *
+ * - "cgroup.procs" is not sorted. pids will be unique unless they got
+ * recycled inbetween reads.
+ *
+ * - "release_agent" and "notify_on_release" are removed. Replacement
+ * notification mechanism will be implemented.
+ *
+ * - "cgroup.clone_children" is removed.
+ *
+ * - "cgroup.subtree_populated" is available. Its value is 0 if the cgroup
+ * and its descendants contain no task; otherwise, 1. The file also
+ * generates kernfs notification which can be monitored through poll and
+ * [di]notify when the value of the file changes.
+ *
+ * - cpuset: tasks will be kept in empty cpusets when hotplug happens and
+ * take masks of ancestors with non-empty cpus/mems, instead of being
+ * moved to an ancestor.
+ *
+ * - cpuset: a task can be moved into an empty cpuset, and again it takes
+ * masks of ancestors.
+ *
+ * - memcg: use_hierarchy is on by default and the cgroup file for the flag
+ * is not created.
+ *
+ * - blkcg: blk-throttle becomes properly hierarchical.
+ *
+ * - debug: disallowed on the default hierarchy.
+ */
+static bool cgroup_on_dfl(const struct cgroup *cgrp)
+{
+ return cgrp->root == &cgrp_dfl_root;
+}
+
+/* IDR wrappers which synchronize using cgroup_idr_lock */
+static int cgroup_idr_alloc(struct idr *idr, void *ptr, int start, int end,
+ gfp_t gfp_mask)
+{
+ int ret;
+
+ idr_preload(gfp_mask);
+ spin_lock_bh(&cgroup_idr_lock);
+ ret = idr_alloc(idr, ptr, start, end, gfp_mask & ~__GFP_DIRECT_RECLAIM);
+ spin_unlock_bh(&cgroup_idr_lock);
+ idr_preload_end();
+ return ret;
+}
+
+static void *cgroup_idr_replace(struct idr *idr, void *ptr, int id)
+{
+ void *ret;
+
+ spin_lock_bh(&cgroup_idr_lock);
+ ret = idr_replace(idr, ptr, id);
+ spin_unlock_bh(&cgroup_idr_lock);
+ return ret;
+}
+
+static void cgroup_idr_remove(struct idr *idr, int id)
+{
+ spin_lock_bh(&cgroup_idr_lock);
+ idr_remove(idr, id);
+ spin_unlock_bh(&cgroup_idr_lock);
+}
+
+static struct cgroup *cgroup_parent(struct cgroup *cgrp)
+{
+ struct cgroup_subsys_state *parent_css = cgrp->self.parent;
+
+ if (parent_css)
+ return container_of(parent_css, struct cgroup, self);
+ return NULL;
+}
+
+/* subsystems visibly enabled on a cgroup */
+static u16 cgroup_control(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ u16 root_ss_mask = cgrp->root->subsys_mask;
+
+ if (parent)
+ return parent->subtree_control;
+
+ if (cgroup_on_dfl(cgrp))
+ root_ss_mask &= ~(cgrp_dfl_inhibit_ss_mask |
+ cgrp_dfl_implicit_ss_mask);
+ return root_ss_mask;
+}
+
+/* subsystems enabled on a cgroup */
+static u16 cgroup_ss_mask(struct cgroup *cgrp)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+
+ if (parent)
+ return parent->subtree_ss_mask;
+
+ return cgrp->root->subsys_mask;
+}
+
+/**
+ * cgroup_css - obtain a cgroup's css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest (%NULL returns @cgrp->self)
+ *
+ * Return @cgrp's css (cgroup_subsys_state) associated with @ss. This
+ * function must be called either under cgroup_mutex or rcu_read_lock() and
+ * the caller is responsible for pinning the returned css if it wants to
+ * keep accessing it outside the said locks. This function may return
+ * %NULL if @cgrp doesn't have @subsys_id enabled.
+ */
+static struct cgroup_subsys_state *cgroup_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ if (ss)
+ return rcu_dereference_check(cgrp->subsys[ss->id],
+ lockdep_is_held(&cgroup_mutex));
+ else
+ return &cgrp->self;
+}
+
+/**
+ * cgroup_e_css - obtain a cgroup's effective css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest (%NULL returns @cgrp->self)
+ *
+ * Similar to cgroup_css() but returns the effective css, which is defined
+ * as the matching css of the nearest ancestor including self which has @ss
+ * enabled. If @ss is associated with the hierarchy @cgrp is on, this
+ * function is guaranteed to return non-NULL css.
+ */
+static struct cgroup_subsys_state *cgroup_e_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (!ss)
+ return &cgrp->self;
+
+ /*
+ * This function is used while updating css associations and thus
+ * can't test the csses directly. Test ss_mask.
+ */
+ while (!(cgroup_ss_mask(cgrp) & (1 << ss->id))) {
+ cgrp = cgroup_parent(cgrp);
+ if (!cgrp)
+ return NULL;
+ }
+
+ return cgroup_css(cgrp, ss);
+}
+
+/**
+ * cgroup_get_e_css - get a cgroup's effective css for the specified subsystem
+ * @cgrp: the cgroup of interest
+ * @ss: the subsystem of interest
+ *
+ * Find and get the effective css of @cgrp for @ss. The effective css is
+ * defined as the matching css of the nearest ancestor including self which
+ * has @ss enabled. If @ss is not mounted on the hierarchy @cgrp is on,
+ * the root css is returned, so this function always returns a valid css.
+ * The returned css must be put using css_put().
+ */
+struct cgroup_subsys_state *cgroup_get_e_css(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup_subsys_state *css;
+
+ rcu_read_lock();
+
+ do {
+ css = cgroup_css(cgrp, ss);
+
+ if (css && css_tryget_online(css))
+ goto out_unlock;
+ cgrp = cgroup_parent(cgrp);
+ } while (cgrp);
+
+ css = init_css_set.subsys[ss->id];
+ css_get(css);
+out_unlock:
+ rcu_read_unlock();
+ return css;
+}
+
+/* convenient tests for these bits */
+static inline bool cgroup_is_dead(const struct cgroup *cgrp)
+{
+ return !(cgrp->self.flags & CSS_ONLINE);
+}
+
+static void cgroup_get(struct cgroup *cgrp)
+{
+ WARN_ON_ONCE(cgroup_is_dead(cgrp));
+ css_get(&cgrp->self);
+}
+
+static bool cgroup_tryget(struct cgroup *cgrp)
+{
+ return css_tryget(&cgrp->self);
+}
+
+struct cgroup_subsys_state *of_css(struct kernfs_open_file *of)
+{
+ struct cgroup *cgrp = of->kn->parent->priv;
+ struct cftype *cft = of_cft(of);
+
+ /*
+ * This is open and unprotected implementation of cgroup_css().
+ * seq_css() is only called from a kernfs file operation which has
+ * an active reference on the file. Because all the subsystem
+ * files are drained before a css is disassociated with a cgroup,
+ * the matching css from the cgroup's subsys table is guaranteed to
+ * be and stay valid until the enclosing operation is complete.
+ */
+ if (cft->ss)
+ return rcu_dereference_raw(cgrp->subsys[cft->ss->id]);
+ else
+ return &cgrp->self;
+}
+EXPORT_SYMBOL_GPL(of_css);
+
+static int notify_on_release(const struct cgroup *cgrp)
+{
+ return test_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+}
+
+/**
+ * for_each_css - iterate all css's of a cgroup
+ * @css: the iteration cursor
+ * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
+ * @cgrp: the target cgroup to iterate css's of
+ *
+ * Should be called under cgroup_[tree_]mutex.
+ */
+#define for_each_css(css, ssid, cgrp) \
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
+ if (!((css) = rcu_dereference_check( \
+ (cgrp)->subsys[(ssid)], \
+ lockdep_is_held(&cgroup_mutex)))) { } \
+ else
+
+/**
+ * for_each_e_css - iterate all effective css's of a cgroup
+ * @css: the iteration cursor
+ * @ssid: the index of the subsystem, CGROUP_SUBSYS_COUNT after reaching the end
+ * @cgrp: the target cgroup to iterate css's of
+ *
+ * Should be called under cgroup_[tree_]mutex.
+ */
+#define for_each_e_css(css, ssid, cgrp) \
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT; (ssid)++) \
+ if (!((css) = cgroup_e_css(cgrp, cgroup_subsys[(ssid)]))) \
+ ; \
+ else
+
+/**
+ * for_each_subsys - iterate all enabled cgroup subsystems
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ */
+#define for_each_subsys(ss, ssid) \
+ for ((ssid) = 0; (ssid) < CGROUP_SUBSYS_COUNT && \
+ (((ss) = cgroup_subsys[ssid]) || true); (ssid)++)
+
+/**
+ * do_each_subsys_mask - filter for_each_subsys with a bitmask
+ * @ss: the iteration cursor
+ * @ssid: the index of @ss, CGROUP_SUBSYS_COUNT after reaching the end
+ * @ss_mask: the bitmask
+ *
+ * The block will only run for cases where the ssid-th bit (1 << ssid) of
+ * @ss_mask is set.
+ */
+#define do_each_subsys_mask(ss, ssid, ss_mask) do { \
+ unsigned long __ss_mask = (ss_mask); \
+ if (!CGROUP_SUBSYS_COUNT) { /* to avoid spurious gcc warning */ \
+ (ssid) = 0; \
+ break; \
+ } \
+ for_each_set_bit(ssid, &__ss_mask, CGROUP_SUBSYS_COUNT) { \
+ (ss) = cgroup_subsys[ssid]; \
+ {
+
+#define while_each_subsys_mask() \
+ } \
+ } \
+} while (false)
+
+/* iterate across the hierarchies */
+#define for_each_root(root) \
+ list_for_each_entry((root), &cgroup_roots, root_list)
+
+/* iterate over child cgrps, lock should be held throughout iteration */
+#define cgroup_for_each_live_child(child, cgrp) \
+ list_for_each_entry((child), &(cgrp)->self.children, self.sibling) \
+ if (({ lockdep_assert_held(&cgroup_mutex); \
+ cgroup_is_dead(child); })) \
+ ; \
+ else
+
+/* walk live descendants in preorder */
+#define cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) \
+ css_for_each_descendant_pre((d_css), cgroup_css((cgrp), NULL)) \
+ if (({ lockdep_assert_held(&cgroup_mutex); \
+ (dsct) = (d_css)->cgroup; \
+ cgroup_is_dead(dsct); })) \
+ ; \
+ else
+
+/* walk live descendants in postorder */
+#define cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) \
+ css_for_each_descendant_post((d_css), cgroup_css((cgrp), NULL)) \
+ if (({ lockdep_assert_held(&cgroup_mutex); \
+ (dsct) = (d_css)->cgroup; \
+ cgroup_is_dead(dsct); })) \
+ ; \
+ else
+
+static void cgroup_release_agent(struct work_struct *work);
+static void check_for_release(struct cgroup *cgrp);
+
+/*
+ * A cgroup can be associated with multiple css_sets as different tasks may
+ * belong to different cgroups on different hierarchies. In the other
+ * direction, a css_set is naturally associated with multiple cgroups.
+ * This M:N relationship is represented by the following link structure
+ * which exists for each association and allows traversing the associations
+ * from both sides.
+ */
+struct cgrp_cset_link {
+ /* the cgroup and css_set this link associates */
+ struct cgroup *cgrp;
+ struct css_set *cset;
+
+ /* list of cgrp_cset_links anchored at cgrp->cset_links */
+ struct list_head cset_link;
+
+ /* list of cgrp_cset_links anchored at css_set->cgrp_links */
+ struct list_head cgrp_link;
+};
+
+/*
+ * The default css_set - used by init and its children prior to any
+ * hierarchies being mounted. It contains a pointer to the root state
+ * for each subsystem. Also used to anchor the list of css_sets. Not
+ * reference-counted, to improve performance when child cgroups
+ * haven't been created.
+ */
+struct css_set init_css_set = {
+ .refcount = ATOMIC_INIT(1),
+ .tasks = LIST_HEAD_INIT(init_css_set.tasks),
+ .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks),
+ .task_iters = LIST_HEAD_INIT(init_css_set.task_iters),
+ .cgrp_links = LIST_HEAD_INIT(init_css_set.cgrp_links),
+ .mg_preload_node = LIST_HEAD_INIT(init_css_set.mg_preload_node),
+ .mg_node = LIST_HEAD_INIT(init_css_set.mg_node),
+};
+
+static int css_set_count = 1; /* 1 for init_css_set */
+
+/**
+ * css_set_populated - does a css_set contain any tasks?
+ * @cset: target css_set
+ */
+static bool css_set_populated(struct css_set *cset)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ return !list_empty(&cset->tasks) || !list_empty(&cset->mg_tasks);
+}
+
+/**
+ * cgroup_update_populated - updated populated count of a cgroup
+ * @cgrp: the target cgroup
+ * @populated: inc or dec populated count
+ *
+ * One of the css_sets associated with @cgrp is either getting its first
+ * task or losing the last. Update @cgrp->populated_cnt accordingly. The
+ * count is propagated towards root so that a given cgroup's populated_cnt
+ * is zero iff the cgroup and all its descendants don't contain any tasks.
+ *
+ * @cgrp's interface file "cgroup.populated" is zero if
+ * @cgrp->populated_cnt is zero and 1 otherwise. When @cgrp->populated_cnt
+ * changes from or to zero, userland is notified that the content of the
+ * interface file has changed. This can be used to detect when @cgrp and
+ * its descendants become populated or empty.
+ */
+static void cgroup_update_populated(struct cgroup *cgrp, bool populated)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ do {
+ bool trigger;
+
+ if (populated)
+ trigger = !cgrp->populated_cnt++;
+ else
+ trigger = !--cgrp->populated_cnt;
+
+ if (!trigger)
+ break;
+
+ check_for_release(cgrp);
+ cgroup_file_notify(&cgrp->events_file);
+
+ cgrp = cgroup_parent(cgrp);
+ } while (cgrp);
+}
+
+/**
+ * css_set_update_populated - update populated state of a css_set
+ * @cset: target css_set
+ * @populated: whether @cset is populated or depopulated
+ *
+ * @cset is either getting the first task or losing the last. Update the
+ * ->populated_cnt of all associated cgroups accordingly.
+ */
+static void css_set_update_populated(struct css_set *cset, bool populated)
+{
+ struct cgrp_cset_link *link;
+
+ lockdep_assert_held(&css_set_lock);
+
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link)
+ cgroup_update_populated(link->cgrp, populated);
+}
+
+/**
+ * css_set_move_task - move a task from one css_set to another
+ * @task: task being moved
+ * @from_cset: css_set @task currently belongs to (may be NULL)
+ * @to_cset: new css_set @task is being moved to (may be NULL)
+ * @use_mg_tasks: move to @to_cset->mg_tasks instead of ->tasks
+ *
+ * Move @task from @from_cset to @to_cset. If @task didn't belong to any
+ * css_set, @from_cset can be NULL. If @task is being disassociated
+ * instead of moved, @to_cset can be NULL.
+ *
+ * This function automatically handles populated_cnt updates and
+ * css_task_iter adjustments but the caller is responsible for managing
+ * @from_cset and @to_cset's reference counts.
+ */
+static void css_set_move_task(struct task_struct *task,
+ struct css_set *from_cset, struct css_set *to_cset,
+ bool use_mg_tasks)
+{
+ lockdep_assert_held(&css_set_lock);
+
+ if (to_cset && !css_set_populated(to_cset))
+ css_set_update_populated(to_cset, true);
+
+ if (from_cset) {
+ struct css_task_iter *it, *pos;
+
+ WARN_ON_ONCE(list_empty(&task->cg_list));
+
+ /*
+ * @task is leaving, advance task iterators which are
+ * pointing to it so that they can resume at the next
+ * position. Advancing an iterator might remove it from
+ * the list, use safe walk. See css_task_iter_advance*()
+ * for details.
+ */
+ list_for_each_entry_safe(it, pos, &from_cset->task_iters,
+ iters_node)
+ if (it->task_pos == &task->cg_list)
+ css_task_iter_advance(it);
+
+ list_del_init(&task->cg_list);
+ if (!css_set_populated(from_cset))
+ css_set_update_populated(from_cset, false);
+ } else {
+ WARN_ON_ONCE(!list_empty(&task->cg_list));
+ }
+
+ if (to_cset) {
+ /*
+ * We are synchronized through cgroup_threadgroup_rwsem
+ * against PF_EXITING setting such that we can't race
+ * against cgroup_exit() changing the css_set to
+ * init_css_set and dropping the old one.
+ */
+ WARN_ON_ONCE(task->flags & PF_EXITING);
+
+ rcu_assign_pointer(task->cgroups, to_cset);
+ list_add_tail(&task->cg_list, use_mg_tasks ? &to_cset->mg_tasks :
+ &to_cset->tasks);
+ }
+}
+
+/*
+ * hash table for cgroup groups. This improves the performance to find
+ * an existing css_set. This hash doesn't (currently) take into
+ * account cgroups in empty hierarchies.
+ */
+#define CSS_SET_HASH_BITS 7
+static DEFINE_HASHTABLE(css_set_table, CSS_SET_HASH_BITS);
+
+static unsigned long css_set_hash(struct cgroup_subsys_state *css[])
+{
+ unsigned long key = 0UL;
+ struct cgroup_subsys *ss;
+ int i;
+
+ for_each_subsys(ss, i)
+ key += (unsigned long)css[i];
+ key = (key >> 16) ^ key;
+
+ return key;
+}
+
+static void put_css_set_locked(struct css_set *cset)
+{
+ struct cgrp_cset_link *link, *tmp_link;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ lockdep_assert_held(&css_set_lock);
+
+ if (!atomic_dec_and_test(&cset->refcount))
+ return;
+
+ /* This css_set is dead. unlink it and release cgroup and css refs */
+ for_each_subsys(ss, ssid) {
+ list_del(&cset->e_cset_node[ssid]);
+ css_put(cset->subsys[ssid]);
+ }
+ hash_del(&cset->hlist);
+ css_set_count--;
+
+ list_for_each_entry_safe(link, tmp_link, &cset->cgrp_links, cgrp_link) {
+ list_del(&link->cset_link);
+ list_del(&link->cgrp_link);
+ if (cgroup_parent(link->cgrp))
+ cgroup_put(link->cgrp);
+ kfree(link);
+ }
+
+ kfree_rcu(cset, rcu_head);
+}
+
+static void put_css_set(struct css_set *cset)
+{
+ unsigned long flags;
+
+ /*
+ * Ensure that the refcount doesn't hit zero while any readers
+ * can see it. Similar to atomic_dec_and_lock(), but for an
+ * rwlock
+ */
+ if (atomic_add_unless(&cset->refcount, -1, 1))
+ return;
+
+ spin_lock_irqsave(&css_set_lock, flags);
+ put_css_set_locked(cset);
+ spin_unlock_irqrestore(&css_set_lock, flags);
+}
+
+/*
+ * refcounted get/put for css_set objects
+ */
+static inline void get_css_set(struct css_set *cset)
+{
+ atomic_inc(&cset->refcount);
+}
+
+/**
+ * compare_css_sets - helper function for find_existing_css_set().
+ * @cset: candidate css_set being tested
+ * @old_cset: existing css_set for a task
+ * @new_cgrp: cgroup that's being entered by the task
+ * @template: desired set of css pointers in css_set (pre-calculated)
+ *
+ * Returns true if "cset" matches "old_cset" except for the hierarchy
+ * which "new_cgrp" belongs to, for which it should match "new_cgrp".
+ */
+static bool compare_css_sets(struct css_set *cset,
+ struct css_set *old_cset,
+ struct cgroup *new_cgrp,
+ struct cgroup_subsys_state *template[])
+{
+ struct list_head *l1, *l2;
+
+ /*
+ * On the default hierarchy, there can be csets which are
+ * associated with the same set of cgroups but different csses.
+ * Let's first ensure that csses match.
+ */
+ if (memcmp(template, cset->subsys, sizeof(cset->subsys)))
+ return false;
+
+ /*
+ * Compare cgroup pointers in order to distinguish between
+ * different cgroups in hierarchies. As different cgroups may
+ * share the same effective css, this comparison is always
+ * necessary.
+ */
+ l1 = &cset->cgrp_links;
+ l2 = &old_cset->cgrp_links;
+ while (1) {
+ struct cgrp_cset_link *link1, *link2;
+ struct cgroup *cgrp1, *cgrp2;
+
+ l1 = l1->next;
+ l2 = l2->next;
+ /* See if we reached the end - both lists are equal length. */
+ if (l1 == &cset->cgrp_links) {
+ BUG_ON(l2 != &old_cset->cgrp_links);
+ break;
+ } else {
+ BUG_ON(l2 == &old_cset->cgrp_links);
+ }
+ /* Locate the cgroups associated with these links. */
+ link1 = list_entry(l1, struct cgrp_cset_link, cgrp_link);
+ link2 = list_entry(l2, struct cgrp_cset_link, cgrp_link);
+ cgrp1 = link1->cgrp;
+ cgrp2 = link2->cgrp;
+ /* Hierarchies should be linked in the same order. */
+ BUG_ON(cgrp1->root != cgrp2->root);
+
+ /*
+ * If this hierarchy is the hierarchy of the cgroup
+ * that's changing, then we need to check that this
+ * css_set points to the new cgroup; if it's any other
+ * hierarchy, then this css_set should point to the
+ * same cgroup as the old css_set.
+ */
+ if (cgrp1->root == new_cgrp->root) {
+ if (cgrp1 != new_cgrp)
+ return false;
+ } else {
+ if (cgrp1 != cgrp2)
+ return false;
+ }
+ }
+ return true;
+}
+
+/**
+ * find_existing_css_set - init css array and find the matching css_set
+ * @old_cset: the css_set that we're using before the cgroup transition
+ * @cgrp: the cgroup that we're moving into
+ * @template: out param for the new set of csses, should be clear on entry
+ */
+static struct css_set *find_existing_css_set(struct css_set *old_cset,
+ struct cgroup *cgrp,
+ struct cgroup_subsys_state *template[])
+{
+ struct cgroup_root *root = cgrp->root;
+ struct cgroup_subsys *ss;
+ struct css_set *cset;
+ unsigned long key;
+ int i;
+
+ /*
+ * Build the set of subsystem state objects that we want to see in the
+ * new css_set. while subsystems can change globally, the entries here
+ * won't change, so no need for locking.
+ */
+ for_each_subsys(ss, i) {
+ if (root->subsys_mask & (1UL << i)) {
+ /*
+ * @ss is in this hierarchy, so we want the
+ * effective css from @cgrp.
+ */
+ template[i] = cgroup_e_css(cgrp, ss);
+ } else {
+ /*
+ * @ss is not in this hierarchy, so we don't want
+ * to change the css.
+ */
+ template[i] = old_cset->subsys[i];
+ }
+ }
+
+ key = css_set_hash(template);
+ hash_for_each_possible(css_set_table, cset, hlist, key) {
+ if (!compare_css_sets(cset, old_cset, cgrp, template))
+ continue;
+
+ /* This css_set matches what we need */
+ return cset;
+ }
+
+ /* No existing cgroup group matched */
+ return NULL;
+}
+
+static void free_cgrp_cset_links(struct list_head *links_to_free)
+{
+ struct cgrp_cset_link *link, *tmp_link;
+
+ list_for_each_entry_safe(link, tmp_link, links_to_free, cset_link) {
+ list_del(&link->cset_link);
+ kfree(link);
+ }
+}
+
+/**
+ * allocate_cgrp_cset_links - allocate cgrp_cset_links
+ * @count: the number of links to allocate
+ * @tmp_links: list_head the allocated links are put on
+ *
+ * Allocate @count cgrp_cset_link structures and chain them on @tmp_links
+ * through ->cset_link. Returns 0 on success or -errno.
+ */
+static int allocate_cgrp_cset_links(int count, struct list_head *tmp_links)
+{
+ struct cgrp_cset_link *link;
+ int i;
+
+ INIT_LIST_HEAD(tmp_links);
+
+ for (i = 0; i < count; i++) {
+ link = kzalloc(sizeof(*link), GFP_KERNEL);
+ if (!link) {
+ free_cgrp_cset_links(tmp_links);
+ return -ENOMEM;
+ }
+ list_add(&link->cset_link, tmp_links);
+ }
+ return 0;
+}
+
+/**
+ * link_css_set - a helper function to link a css_set to a cgroup
+ * @tmp_links: cgrp_cset_link objects allocated by allocate_cgrp_cset_links()
+ * @cset: the css_set to be linked
+ * @cgrp: the destination cgroup
+ */
+static void link_css_set(struct list_head *tmp_links, struct css_set *cset,
+ struct cgroup *cgrp)
+{
+ struct cgrp_cset_link *link;
+
+ BUG_ON(list_empty(tmp_links));
+
+ if (cgroup_on_dfl(cgrp))
+ cset->dfl_cgrp = cgrp;
+
+ link = list_first_entry(tmp_links, struct cgrp_cset_link, cset_link);
+ link->cset = cset;
+ link->cgrp = cgrp;
+
+ /*
+ * Always add links to the tail of the lists so that the lists are
+ * in choronological order.
+ */
+ list_move_tail(&link->cset_link, &cgrp->cset_links);
+ list_add_tail(&link->cgrp_link, &cset->cgrp_links);
+
+ if (cgroup_parent(cgrp))
+ cgroup_get(cgrp);
+}
+
+/**
+ * find_css_set - return a new css_set with one cgroup updated
+ * @old_cset: the baseline css_set
+ * @cgrp: the cgroup to be updated
+ *
+ * Return a new css_set that's equivalent to @old_cset, but with @cgrp
+ * substituted into the appropriate hierarchy.
+ */
+static struct css_set *find_css_set(struct css_set *old_cset,
+ struct cgroup *cgrp)
+{
+ struct cgroup_subsys_state *template[CGROUP_SUBSYS_COUNT] = { };
+ struct css_set *cset;
+ struct list_head tmp_links;
+ struct cgrp_cset_link *link;
+ struct cgroup_subsys *ss;
+ unsigned long key;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* First see if we already have a cgroup group that matches
+ * the desired set */
+ spin_lock_irq(&css_set_lock);
+ cset = find_existing_css_set(old_cset, cgrp, template);
+ if (cset)
+ get_css_set(cset);
+ spin_unlock_irq(&css_set_lock);
+
+ if (cset)
+ return cset;
+
+ cset = kzalloc(sizeof(*cset), GFP_KERNEL);
+ if (!cset)
+ return NULL;
+
+ /* Allocate all the cgrp_cset_link objects that we'll need */
+ if (allocate_cgrp_cset_links(cgroup_root_count, &tmp_links) < 0) {
+ kfree(cset);
+ return NULL;
+ }
+
+ atomic_set(&cset->refcount, 1);
+ INIT_LIST_HEAD(&cset->tasks);
+ INIT_LIST_HEAD(&cset->mg_tasks);
+ INIT_LIST_HEAD(&cset->task_iters);
+ INIT_HLIST_NODE(&cset->hlist);
+ INIT_LIST_HEAD(&cset->cgrp_links);
+ INIT_LIST_HEAD(&cset->mg_preload_node);
+ INIT_LIST_HEAD(&cset->mg_node);
+
+ /* Copy the set of subsystem state objects generated in
+ * find_existing_css_set() */
+ memcpy(cset->subsys, template, sizeof(cset->subsys));
+
+ spin_lock_irq(&css_set_lock);
+ /* Add reference counts and links from the new css_set. */
+ list_for_each_entry(link, &old_cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ if (c->root == cgrp->root)
+ c = cgrp;
+ link_css_set(&tmp_links, cset, c);
+ }
+
+ BUG_ON(!list_empty(&tmp_links));
+
+ css_set_count++;
+
+ /* Add @cset to the hash table */
+ key = css_set_hash(cset->subsys);
+ hash_add(css_set_table, &cset->hlist, key);
+
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cset->subsys[ssid];
+
+ list_add_tail(&cset->e_cset_node[ssid],
+ &css->cgroup->e_csets[ssid]);
+ css_get(css);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ return cset;
+}
+
+static struct cgroup_root *cgroup_root_from_kf(struct kernfs_root *kf_root)
+{
+ struct cgroup *root_cgrp = kf_root->kn->priv;
+
+ return root_cgrp->root;
+}
+
+static int cgroup_init_root_id(struct cgroup_root *root)
+{
+ int id;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ id = idr_alloc_cyclic(&cgroup_hierarchy_idr, root, 0, 0, GFP_KERNEL);
+ if (id < 0)
+ return id;
+
+ root->hierarchy_id = id;
+ return 0;
+}
+
+static void cgroup_exit_root_id(struct cgroup_root *root)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ idr_remove(&cgroup_hierarchy_idr, root->hierarchy_id);
+}
+
+static void cgroup_free_root(struct cgroup_root *root)
+{
+ if (root) {
+ idr_destroy(&root->cgroup_idr);
+ kfree(root);
+ }
+}
+
+static void cgroup_destroy_root(struct cgroup_root *root)
+{
+ struct cgroup *cgrp = &root->cgrp;
+ struct cgrp_cset_link *link, *tmp_link;
+
+ trace_cgroup_destroy_root(root);
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ BUG_ON(atomic_read(&root->nr_cgrps));
+ BUG_ON(!list_empty(&cgrp->self.children));
+
+ /* Rebind all subsystems back to the default hierarchy */
+ WARN_ON(rebind_subsystems(&cgrp_dfl_root, root->subsys_mask));
+
+ /*
+ * Release all the links from cset_links to this hierarchy's
+ * root cgroup
+ */
+ spin_lock_irq(&css_set_lock);
+
+ list_for_each_entry_safe(link, tmp_link, &cgrp->cset_links, cset_link) {
+ list_del(&link->cset_link);
+ list_del(&link->cgrp_link);
+ kfree(link);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ if (!list_empty(&root->root_list)) {
+ list_del(&root->root_list);
+ cgroup_root_count--;
+ }
+
+ cgroup_exit_root_id(root);
+
+ mutex_unlock(&cgroup_mutex);
+
+ kernfs_destroy_root(root->kf_root);
+ cgroup_free_root(root);
+}
+
+/*
+ * look up cgroup associated with current task's cgroup namespace on the
+ * specified hierarchy
+ */
+static struct cgroup *
+current_cgns_cgroup_from_root(struct cgroup_root *root)
+{
+ struct cgroup *res = NULL;
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ rcu_read_lock();
+
+ cset = current->nsproxy->cgroup_ns->root_cset;
+ if (cset == &init_css_set) {
+ res = &root->cgrp;
+ } else {
+ struct cgrp_cset_link *link;
+
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ if (c->root == root) {
+ res = c;
+ break;
+ }
+ }
+ }
+ rcu_read_unlock();
+
+ BUG_ON(!res);
+ return res;
+}
+
+/* look up cgroup associated with given css_set on the specified hierarchy */
+static struct cgroup *cset_cgroup_from_root(struct css_set *cset,
+ struct cgroup_root *root)
+{
+ struct cgroup *res = NULL;
+
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_lock);
+
+ if (cset == &init_css_set) {
+ res = &root->cgrp;
+ } else {
+ struct cgrp_cset_link *link;
+
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ if (c->root == root) {
+ res = c;
+ break;
+ }
+ }
+ }
+
+ BUG_ON(!res);
+ return res;
+}
+
+/*
+ * Return the cgroup for "task" from the given hierarchy. Must be
+ * called with cgroup_mutex and css_set_lock held.
+ */
+static struct cgroup *task_cgroup_from_root(struct task_struct *task,
+ struct cgroup_root *root)
+{
+ /*
+ * No need to lock the task - since we hold cgroup_mutex the
+ * task can't change groups, so the only thing that can happen
+ * is that it exits and its css is set back to init_css_set.
+ */
+ return cset_cgroup_from_root(task_css_set(task), root);
+}
+
+/*
+ * A task must hold cgroup_mutex to modify cgroups.
+ *
+ * Any task can increment and decrement the count field without lock.
+ * So in general, code holding cgroup_mutex can't rely on the count
+ * field not changing. However, if the count goes to zero, then only
+ * cgroup_attach_task() can increment it again. Because a count of zero
+ * means that no tasks are currently attached, therefore there is no
+ * way a task attached to that cgroup can fork (the other way to
+ * increment the count). So code holding cgroup_mutex can safely
+ * assume that if the count is zero, it will stay zero. Similarly, if
+ * a task holds cgroup_mutex on a cgroup with zero count, it
+ * knows that the cgroup won't be removed, as cgroup_rmdir()
+ * needs that mutex.
+ *
+ * A cgroup can only be deleted if both its 'count' of using tasks
+ * is zero, and its list of 'children' cgroups is empty. Since all
+ * tasks in the system use _some_ cgroup, and since there is always at
+ * least one task in the system (init, pid == 1), therefore, root cgroup
+ * always has either children cgroups and/or using tasks. So we don't
+ * need a special hack to ensure that root cgroup cannot be deleted.
+ *
+ * P.S. One more locking exception. RCU is used to guard the
+ * update of a tasks cgroup pointer by cgroup_attach_task()
+ */
+
+static struct kernfs_syscall_ops cgroup_kf_syscall_ops;
+static const struct file_operations proc_cgroupstats_operations;
+
+static char *cgroup_file_name(struct cgroup *cgrp, const struct cftype *cft,
+ char *buf)
+{
+ struct cgroup_subsys *ss = cft->ss;
+
+ if (cft->ss && !(cft->flags & CFTYPE_NO_PREFIX) &&
+ !(cgrp->root->flags & CGRP_ROOT_NOPREFIX))
+ snprintf(buf, CGROUP_FILE_NAME_MAX, "%s.%s",
+ cgroup_on_dfl(cgrp) ? ss->name : ss->legacy_name,
+ cft->name);
+ else
+ strncpy(buf, cft->name, CGROUP_FILE_NAME_MAX);
+ return buf;
+}
+
+/**
+ * cgroup_file_mode - deduce file mode of a control file
+ * @cft: the control file in question
+ *
+ * S_IRUGO for read, S_IWUSR for write.
+ */
+static umode_t cgroup_file_mode(const struct cftype *cft)
+{
+ umode_t mode = 0;
+
+ if (cft->read_u64 || cft->read_s64 || cft->seq_show)
+ mode |= S_IRUGO;
+
+ if (cft->write_u64 || cft->write_s64 || cft->write) {
+ if (cft->flags & CFTYPE_WORLD_WRITABLE)
+ mode |= S_IWUGO;
+ else
+ mode |= S_IWUSR;
+ }
+
+ return mode;
+}
+
+/**
+ * cgroup_calc_subtree_ss_mask - calculate subtree_ss_mask
+ * @subtree_control: the new subtree_control mask to consider
+ * @this_ss_mask: available subsystems
+ *
+ * On the default hierarchy, a subsystem may request other subsystems to be
+ * enabled together through its ->depends_on mask. In such cases, more
+ * subsystems than specified in "cgroup.subtree_control" may be enabled.
+ *
+ * This function calculates which subsystems need to be enabled if
+ * @subtree_control is to be applied while restricted to @this_ss_mask.
+ */
+static u16 cgroup_calc_subtree_ss_mask(u16 subtree_control, u16 this_ss_mask)
+{
+ u16 cur_ss_mask = subtree_control;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ cur_ss_mask |= cgrp_dfl_implicit_ss_mask;
+
+ while (true) {
+ u16 new_ss_mask = cur_ss_mask;
+
+ do_each_subsys_mask(ss, ssid, cur_ss_mask) {
+ new_ss_mask |= ss->depends_on;
+ } while_each_subsys_mask();
+
+ /*
+ * Mask out subsystems which aren't available. This can
+ * happen only if some depended-upon subsystems were bound
+ * to non-default hierarchies.
+ */
+ new_ss_mask &= this_ss_mask;
+
+ if (new_ss_mask == cur_ss_mask)
+ break;
+ cur_ss_mask = new_ss_mask;
+ }
+
+ return cur_ss_mask;
+}
+
+/**
+ * cgroup_kn_unlock - unlocking helper for cgroup kernfs methods
+ * @kn: the kernfs_node being serviced
+ *
+ * This helper undoes cgroup_kn_lock_live() and should be invoked before
+ * the method finishes if locking succeeded. Note that once this function
+ * returns the cgroup returned by cgroup_kn_lock_live() may become
+ * inaccessible any time. If the caller intends to continue to access the
+ * cgroup, it should pin it before invoking this function.
+ */
+static void cgroup_kn_unlock(struct kernfs_node *kn)
+{
+ struct cgroup *cgrp;
+
+ if (kernfs_type(kn) == KERNFS_DIR)
+ cgrp = kn->priv;
+ else
+ cgrp = kn->parent->priv;
+
+ mutex_unlock(&cgroup_mutex);
+
+ kernfs_unbreak_active_protection(kn);
+ cgroup_put(cgrp);
+}
+
+/**
+ * cgroup_kn_lock_live - locking helper for cgroup kernfs methods
+ * @kn: the kernfs_node being serviced
+ * @drain_offline: perform offline draining on the cgroup
+ *
+ * This helper is to be used by a cgroup kernfs method currently servicing
+ * @kn. It breaks the active protection, performs cgroup locking and
+ * verifies that the associated cgroup is alive. Returns the cgroup if
+ * alive; otherwise, %NULL. A successful return should be undone by a
+ * matching cgroup_kn_unlock() invocation. If @drain_offline is %true, the
+ * cgroup is drained of offlining csses before return.
+ *
+ * Any cgroup kernfs method implementation which requires locking the
+ * associated cgroup should use this helper. It avoids nesting cgroup
+ * locking under kernfs active protection and allows all kernfs operations
+ * including self-removal.
+ */
+static struct cgroup *cgroup_kn_lock_live(struct kernfs_node *kn,
+ bool drain_offline)
+{
+ struct cgroup *cgrp;
+
+ if (kernfs_type(kn) == KERNFS_DIR)
+ cgrp = kn->priv;
+ else
+ cgrp = kn->parent->priv;
+
+ /*
+ * We're gonna grab cgroup_mutex which nests outside kernfs
+ * active_ref. cgroup liveliness check alone provides enough
+ * protection against removal. Ensure @cgrp stays accessible and
+ * break the active_ref protection.
+ */
+ if (!cgroup_tryget(cgrp))
+ return NULL;
+ kernfs_break_active_protection(kn);
+
+ if (drain_offline)
+ cgroup_lock_and_drain_offline(cgrp);
+ else
+ mutex_lock(&cgroup_mutex);
+
+ if (!cgroup_is_dead(cgrp))
+ return cgrp;
+
+ cgroup_kn_unlock(kn);
+ return NULL;
+}
+
+static void cgroup_rm_file(struct cgroup *cgrp, const struct cftype *cft)
+{
+ char name[CGROUP_FILE_NAME_MAX];
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (cft->file_offset) {
+ struct cgroup_subsys_state *css = cgroup_css(cgrp, cft->ss);
+ struct cgroup_file *cfile = (void *)css + cft->file_offset;
+
+ spin_lock_irq(&cgroup_file_kn_lock);
+ cfile->kn = NULL;
+ spin_unlock_irq(&cgroup_file_kn_lock);
+ }
+
+ kernfs_remove_by_name(cgrp->kn, cgroup_file_name(cgrp, cft, name));
+}
+
+/**
+ * css_clear_dir - remove subsys files in a cgroup directory
+ * @css: taget css
+ */
+static void css_clear_dir(struct cgroup_subsys_state *css)
+{
+ struct cgroup *cgrp = css->cgroup;
+ struct cftype *cfts;
+
+ if (!(css->flags & CSS_VISIBLE))
+ return;
+
+ css->flags &= ~CSS_VISIBLE;
+
+ list_for_each_entry(cfts, &css->ss->cfts, node)
+ cgroup_addrm_files(css, cgrp, cfts, false);
+}
+
+/**
+ * css_populate_dir - create subsys files in a cgroup directory
+ * @css: target css
+ *
+ * On failure, no file is added.
+ */
+static int css_populate_dir(struct cgroup_subsys_state *css)
+{
+ struct cgroup *cgrp = css->cgroup;
+ struct cftype *cfts, *failed_cfts;
+ int ret;
+
+ if ((css->flags & CSS_VISIBLE) || !cgrp->kn)
+ return 0;
+
+ if (!css->ss) {
+ if (cgroup_on_dfl(cgrp))
+ cfts = cgroup_dfl_base_files;
+ else
+ cfts = cgroup_legacy_base_files;
+
+ return cgroup_addrm_files(&cgrp->self, cgrp, cfts, true);
+ }
+
+ list_for_each_entry(cfts, &css->ss->cfts, node) {
+ ret = cgroup_addrm_files(css, cgrp, cfts, true);
+ if (ret < 0) {
+ failed_cfts = cfts;
+ goto err;
+ }
+ }
+
+ css->flags |= CSS_VISIBLE;
+
+ return 0;
+err:
+ list_for_each_entry(cfts, &css->ss->cfts, node) {
+ if (cfts == failed_cfts)
+ break;
+ cgroup_addrm_files(css, cgrp, cfts, false);
+ }
+ return ret;
+}
+
+static int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask)
+{
+ struct cgroup *dcgrp = &dst_root->cgrp;
+ struct cgroup_subsys *ss;
+ int ssid, i, ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ do_each_subsys_mask(ss, ssid, ss_mask) {
+ /*
+ * If @ss has non-root csses attached to it, can't move.
+ * If @ss is an implicit controller, it is exempt from this
+ * rule and can be stolen.
+ */
+ if (css_next_child(NULL, cgroup_css(&ss->root->cgrp, ss)) &&
+ !ss->implicit_on_dfl)
+ return -EBUSY;
+
+ /* can't move between two non-dummy roots either */
+ if (ss->root != &cgrp_dfl_root && dst_root != &cgrp_dfl_root)
+ return -EBUSY;
+ } while_each_subsys_mask();
+
+ do_each_subsys_mask(ss, ssid, ss_mask) {
+ struct cgroup_root *src_root = ss->root;
+ struct cgroup *scgrp = &src_root->cgrp;
+ struct cgroup_subsys_state *css = cgroup_css(scgrp, ss);
+ struct css_set *cset;
+
+ WARN_ON(!css || cgroup_css(dcgrp, ss));
+
+ /* disable from the source */
+ src_root->subsys_mask &= ~(1 << ssid);
+ WARN_ON(cgroup_apply_control(scgrp));
+ cgroup_finalize_control(scgrp, 0);
+
+ /* rebind */
+ RCU_INIT_POINTER(scgrp->subsys[ssid], NULL);
+ rcu_assign_pointer(dcgrp->subsys[ssid], css);
+ ss->root = dst_root;
+ css->cgroup = dcgrp;
+
+ spin_lock_irq(&css_set_lock);
+ hash_for_each(css_set_table, i, cset, hlist)
+ list_move_tail(&cset->e_cset_node[ss->id],
+ &dcgrp->e_csets[ss->id]);
+ spin_unlock_irq(&css_set_lock);
+
+ /* default hierarchy doesn't enable controllers by default */
+ dst_root->subsys_mask |= 1 << ssid;
+ if (dst_root == &cgrp_dfl_root) {
+ static_branch_enable(cgroup_subsys_on_dfl_key[ssid]);
+ } else {
+ dcgrp->subtree_control |= 1 << ssid;
+ static_branch_disable(cgroup_subsys_on_dfl_key[ssid]);
+ }
+
+ ret = cgroup_apply_control(dcgrp);
+ if (ret)
+ pr_warn("partial failure to rebind %s controller (err=%d)\n",
+ ss->name, ret);
+
+ if (ss->bind)
+ ss->bind(css);
+ } while_each_subsys_mask();
+
+ kernfs_activate(dcgrp->kn);
+ return 0;
+}
+
+static int cgroup_show_path(struct seq_file *sf, struct kernfs_node *kf_node,
+ struct kernfs_root *kf_root)
+{
+ int len = 0;
+ char *buf = NULL;
+ struct cgroup_root *kf_cgroot = cgroup_root_from_kf(kf_root);
+ struct cgroup *ns_cgroup;
+
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ spin_lock_irq(&css_set_lock);
+ ns_cgroup = current_cgns_cgroup_from_root(kf_cgroot);
+ len = kernfs_path_from_node(kf_node, ns_cgroup->kn, buf, PATH_MAX);
+ spin_unlock_irq(&css_set_lock);
+
+ if (len >= PATH_MAX)
+ len = -ERANGE;
+ else if (len > 0) {
+ seq_escape(sf, buf, " \t\n\\");
+ len = 0;
+ }
+ kfree(buf);
+ return len;
+}
+
+static int cgroup_show_options(struct seq_file *seq,
+ struct kernfs_root *kf_root)
+{
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ if (root != &cgrp_dfl_root)
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_show_option(seq, ss->legacy_name, NULL);
+ if (root->flags & CGRP_ROOT_NOPREFIX)
+ seq_puts(seq, ",noprefix");
+ if (root->flags & CGRP_ROOT_XATTR)
+ seq_puts(seq, ",xattr");
+
+ spin_lock(&release_agent_path_lock);
+ if (strlen(root->release_agent_path))
+ seq_show_option(seq, "release_agent",
+ root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
+ seq_puts(seq, ",clone_children");
+ if (strlen(root->name))
+ seq_show_option(seq, "name", root->name);
+ return 0;
+}
+
+struct cgroup_sb_opts {
+ u16 subsys_mask;
+ unsigned int flags;
+ char *release_agent;
+ bool cpuset_clone_children;
+ char *name;
+ /* User explicitly requested empty subsystem */
+ bool none;
+};
+
+static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)
+{
+ char *token, *o = data;
+ bool all_ss = false, one_ss = false;
+ u16 mask = U16_MAX;
+ struct cgroup_subsys *ss;
+ int nr_opts = 0;
+ int i;
+
+#ifdef CONFIG_CPUSETS
+ mask = ~((u16)1 << cpuset_cgrp_id);
+#endif
+
+ memset(opts, 0, sizeof(*opts));
+
+ while ((token = strsep(&o, ",")) != NULL) {
+ nr_opts++;
+
+ if (!*token)
+ return -EINVAL;
+ if (!strcmp(token, "none")) {
+ /* Explicitly have no subsystems */
+ opts->none = true;
+ continue;
+ }
+ if (!strcmp(token, "all")) {
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (one_ss)
+ return -EINVAL;
+ all_ss = true;
+ continue;
+ }
+ if (!strcmp(token, "noprefix")) {
+ opts->flags |= CGRP_ROOT_NOPREFIX;
+ continue;
+ }
+ if (!strcmp(token, "clone_children")) {
+ opts->cpuset_clone_children = true;
+ continue;
+ }
+ if (!strcmp(token, "xattr")) {
+ opts->flags |= CGRP_ROOT_XATTR;
+ continue;
+ }
+ if (!strncmp(token, "release_agent=", 14)) {
+ /* Specifying two release agents is forbidden */
+ if (opts->release_agent)
+ return -EINVAL;
+ opts->release_agent =
+ kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
+ if (!opts->release_agent)
+ return -ENOMEM;
+ continue;
+ }
+ if (!strncmp(token, "name=", 5)) {
+ const char *name = token + 5;
+ /* Can't specify an empty name */
+ if (!strlen(name))
+ return -EINVAL;
+ /* Must match [\w.-]+ */
+ for (i = 0; i < strlen(name); i++) {
+ char c = name[i];
+ if (isalnum(c))
+ continue;
+ if ((c == '.') || (c == '-') || (c == '_'))
+ continue;
+ return -EINVAL;
+ }
+ /* Specifying two names is forbidden */
+ if (opts->name)
+ return -EINVAL;
+ opts->name = kstrndup(name,
+ MAX_CGROUP_ROOT_NAMELEN - 1,
+ GFP_KERNEL);
+ if (!opts->name)
+ return -ENOMEM;
+
+ continue;
+ }
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->legacy_name))
+ continue;
+ if (!cgroup_ssid_enabled(i))
+ continue;
+ if (cgroup_ssid_no_v1(i))
+ continue;
+
+ /* Mutually exclusive option 'all' + subsystem name */
+ if (all_ss)
+ return -EINVAL;
+ opts->subsys_mask |= (1 << i);
+ one_ss = true;
+
+ break;
+ }
+ if (i == CGROUP_SUBSYS_COUNT)
+ return -ENOENT;
+ }
+
+ /*
+ * If the 'all' option was specified select all the subsystems,
+ * otherwise if 'none', 'name=' and a subsystem name options were
+ * not specified, let's default to 'all'
+ */
+ if (all_ss || (!one_ss && !opts->none && !opts->name))
+ for_each_subsys(ss, i)
+ if (cgroup_ssid_enabled(i) && !cgroup_ssid_no_v1(i))
+ opts->subsys_mask |= (1 << i);
+
+ /*
+ * We either have to specify by name or by subsystems. (So all
+ * empty hierarchies must have a name).
+ */
+ if (!opts->subsys_mask && !opts->name)
+ return -EINVAL;
+
+ /*
+ * Option noprefix was introduced just for backward compatibility
+ * with the old cpuset, so we allow noprefix only if mounting just
+ * the cpuset subsystem.
+ */
+ if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))
+ return -EINVAL;
+
+ /* Can't specify "none" and some subsystems */
+ if (opts->subsys_mask && opts->none)
+ return -EINVAL;
+
+ return 0;
+}
+
+static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data)
+{
+ int ret = 0;
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+ struct cgroup_sb_opts opts;
+ u16 added_mask, removed_mask;
+
+ if (root == &cgrp_dfl_root) {
+ pr_err("remount is not allowed\n");
+ return -EINVAL;
+ }
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ /* See what subsystems are wanted */
+ ret = parse_cgroupfs_options(data, &opts);
+ if (ret)
+ goto out_unlock;
+
+ if (opts.subsys_mask != root->subsys_mask || opts.release_agent)
+ pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",
+ task_tgid_nr(current), current->comm);
+
+ added_mask = opts.subsys_mask & ~root->subsys_mask;
+ removed_mask = root->subsys_mask & ~opts.subsys_mask;
+
+ /* Don't allow flags or name to change at remount */
+ if ((opts.flags ^ root->flags) ||
+ (opts.name && strcmp(opts.name, root->name))) {
+ pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",
+ opts.flags, opts.name ?: "", root->flags, root->name);
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* remounting is not allowed for populated hierarchies */
+ if (!list_empty(&root->cgrp.self.children)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ ret = rebind_subsystems(root, added_mask);
+ if (ret)
+ goto out_unlock;
+
+ WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));
+
+ if (opts.release_agent) {
+ spin_lock(&release_agent_path_lock);
+ strcpy(root->release_agent_path, opts.release_agent);
+ spin_unlock(&release_agent_path_lock);
+ }
+
+ trace_cgroup_remount(root);
+
+ out_unlock:
+ kfree(opts.release_agent);
+ kfree(opts.name);
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
+/*
+ * To reduce the fork() overhead for systems that are not actually using
+ * their cgroups capability, we don't maintain the lists running through
+ * each css_set to its tasks until we see the list actually used - in other
+ * words after the first mount.
+ */
+static bool use_task_css_set_links __read_mostly;
+
+static void cgroup_enable_task_cg_lists(void)
+{
+ struct task_struct *p, *g;
+
+ spin_lock_irq(&css_set_lock);
+
+ if (use_task_css_set_links)
+ goto out_unlock;
+
+ use_task_css_set_links = true;
+
+ /*
+ * We need tasklist_lock because RCU is not safe against
+ * while_each_thread(). Besides, a forking task that has passed
+ * cgroup_post_fork() without seeing use_task_css_set_links = 1
+ * is not guaranteed to have its child immediately visible in the
+ * tasklist if we walk through it with RCU.
+ */
+ read_lock(&tasklist_lock);
+ do_each_thread(g, p) {
+ WARN_ON_ONCE(!list_empty(&p->cg_list) ||
+ task_css_set(p) != &init_css_set);
+
+ /*
+ * We should check if the process is exiting, otherwise
+ * it will race with cgroup_exit() in that the list
+ * entry won't be deleted though the process has exited.
+ * Do it while holding siglock so that we don't end up
+ * racing against cgroup_exit().
+ *
+ * Interrupts were already disabled while acquiring
+ * the css_set_lock, so we do not need to disable it
+ * again when acquiring the sighand->siglock here.
+ */
+ spin_lock(&p->sighand->siglock);
+ if (!(p->flags & PF_EXITING)) {
+ struct css_set *cset = task_css_set(p);
+
+ if (!css_set_populated(cset))
+ css_set_update_populated(cset, true);
+ list_add_tail(&p->cg_list, &cset->tasks);
+ get_css_set(cset);
+ }
+ spin_unlock(&p->sighand->siglock);
+ } while_each_thread(g, p);
+ read_unlock(&tasklist_lock);
+out_unlock:
+ spin_unlock_irq(&css_set_lock);
+}
+
+static void init_cgroup_housekeeping(struct cgroup *cgrp)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ INIT_LIST_HEAD(&cgrp->self.sibling);
+ INIT_LIST_HEAD(&cgrp->self.children);
+ INIT_LIST_HEAD(&cgrp->cset_links);
+ INIT_LIST_HEAD(&cgrp->pidlists);
+ mutex_init(&cgrp->pidlist_mutex);
+ cgrp->self.cgroup = cgrp;
+ cgrp->self.flags |= CSS_ONLINE;
+
+ for_each_subsys(ss, ssid)
+ INIT_LIST_HEAD(&cgrp->e_csets[ssid]);
+
+ init_waitqueue_head(&cgrp->offline_waitq);
+ INIT_WORK(&cgrp->release_agent_work, cgroup_release_agent);
+}
+
+static void init_cgroup_root(struct cgroup_root *root,
+ struct cgroup_sb_opts *opts)
+{
+ struct cgroup *cgrp = &root->cgrp;
+
+ INIT_LIST_HEAD(&root->root_list);
+ atomic_set(&root->nr_cgrps, 1);
+ cgrp->root = root;
+ init_cgroup_housekeeping(cgrp);
+ idr_init(&root->cgroup_idr);
+
+ root->flags = opts->flags;
+ if (opts->release_agent)
+ strcpy(root->release_agent_path, opts->release_agent);
+ if (opts->name)
+ strcpy(root->name, opts->name);
+ if (opts->cpuset_clone_children)
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);
+}
+
+static int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask)
+{
+ LIST_HEAD(tmp_links);
+ struct cgroup *root_cgrp = &root->cgrp;
+ struct css_set *cset;
+ int i, ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ ret = cgroup_idr_alloc(&root->cgroup_idr, root_cgrp, 1, 2, GFP_KERNEL);
+ if (ret < 0)
+ goto out;
+ root_cgrp->id = ret;
+ root_cgrp->ancestor_ids[0] = ret;
+
+ ret = percpu_ref_init(&root_cgrp->self.refcnt, css_release, 0,
+ GFP_KERNEL);
+ if (ret)
+ goto out;
+
+ /*
+ * We're accessing css_set_count without locking css_set_lock here,
+ * but that's OK - it can only be increased by someone holding
+ * cgroup_lock, and that's us. Later rebinding may disable
+ * controllers on the default hierarchy and thus create new csets,
+ * which can't be more than the existing ones. Allocate 2x.
+ */
+ ret = allocate_cgrp_cset_links(2 * css_set_count, &tmp_links);
+ if (ret)
+ goto cancel_ref;
+
+ ret = cgroup_init_root_id(root);
+ if (ret)
+ goto cancel_ref;
+
+ root->kf_root = kernfs_create_root(&cgroup_kf_syscall_ops,
+ KERNFS_ROOT_CREATE_DEACTIVATED,
+ root_cgrp);
+ if (IS_ERR(root->kf_root)) {
+ ret = PTR_ERR(root->kf_root);
+ goto exit_root_id;
+ }
+ root_cgrp->kn = root->kf_root->kn;
+
+ ret = css_populate_dir(&root_cgrp->self);
+ if (ret)
+ goto destroy_root;
+
+ ret = rebind_subsystems(root, ss_mask);
+ if (ret)
+ goto destroy_root;
+
+ trace_cgroup_setup_root(root);
+
+ /*
+ * There must be no failure case after here, since rebinding takes
+ * care of subsystems' refcounts, which are explicitly dropped in
+ * the failure exit path.
+ */
+ list_add(&root->root_list, &cgroup_roots);
+ cgroup_root_count++;
+
+ /*
+ * Link the root cgroup in this hierarchy into all the css_set
+ * objects.
+ */
+ spin_lock_irq(&css_set_lock);
+ hash_for_each(css_set_table, i, cset, hlist) {
+ link_css_set(&tmp_links, cset, root_cgrp);
+ if (css_set_populated(cset))
+ cgroup_update_populated(root_cgrp, true);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ BUG_ON(!list_empty(&root_cgrp->self.children));
+ BUG_ON(atomic_read(&root->nr_cgrps) != 1);
+
+ kernfs_activate(root_cgrp->kn);
+ ret = 0;
+ goto out;
+
+destroy_root:
+ kernfs_destroy_root(root->kf_root);
+ root->kf_root = NULL;
+exit_root_id:
+ cgroup_exit_root_id(root);
+cancel_ref:
+ percpu_ref_exit(&root_cgrp->self.refcnt);
+out:
+ free_cgrp_cset_links(&tmp_links);
+ return ret;
+}
+
+static struct dentry *cgroup_mount(struct file_system_type *fs_type,
+ int flags, const char *unused_dev_name,
+ void *data)
+{
+ bool is_v2 = fs_type == &cgroup2_fs_type;
+ struct super_block *pinned_sb = NULL;
+ struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;
+ struct cgroup_subsys *ss;
+ struct cgroup_root *root;
+ struct cgroup_sb_opts opts;
+ struct dentry *dentry;
+ int ret;
+ int i;
+ bool new_sb;
+
+ get_cgroup_ns(ns);
+
+ /* Check if the caller has permission to mount. */
+ if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN)) {
+ put_cgroup_ns(ns);
+ return ERR_PTR(-EPERM);
+ }
+
+ /*
+ * The first time anyone tries to mount a cgroup, enable the list
+ * linking each css_set to its tasks and fix up all existing tasks.
+ */
+ if (!use_task_css_set_links)
+ cgroup_enable_task_cg_lists();
+
+ if (is_v2) {
+ if (data) {
+ pr_err("cgroup2: unknown option \"%s\"\n", (char *)data);
+ put_cgroup_ns(ns);
+ return ERR_PTR(-EINVAL);
+ }
+ cgrp_dfl_visible = true;
+ root = &cgrp_dfl_root;
+ cgroup_get(&root->cgrp);
+ goto out_mount;
+ }
+
+ cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
+
+ /* First find the desired set of subsystems */
+ ret = parse_cgroupfs_options(data, &opts);
+ if (ret)
+ goto out_unlock;
+
+ /*
+ * Destruction of cgroup root is asynchronous, so subsystems may
+ * still be dying after the previous unmount. Let's drain the
+ * dying subsystems. We just need to ensure that the ones
+ * unmounted previously finish dying and don't care about new ones
+ * starting. Testing ref liveliness is good enough.
+ */
+ for_each_subsys(ss, i) {
+ if (!(opts.subsys_mask & (1 << i)) ||
+ ss->root == &cgrp_dfl_root)
+ continue;
+
+ if (!percpu_ref_tryget_live(&ss->root->cgrp.self.refcnt)) {
+ mutex_unlock(&cgroup_mutex);
+ msleep(10);
+ ret = restart_syscall();
+ goto out_free;
+ }
+ cgroup_put(&ss->root->cgrp);
+ }
+
+ for_each_root(root) {
+ bool name_match = false;
+
+ if (root == &cgrp_dfl_root)
+ continue;
+
+ /*
+ * If we asked for a name then it must match. Also, if
+ * name matches but sybsys_mask doesn't, we should fail.
+ * Remember whether name matched.
+ */
+ if (opts.name) {
+ if (strcmp(opts.name, root->name))
+ continue;
+ name_match = true;
+ }
+
+ /*
+ * If we asked for subsystems (or explicitly for no
+ * subsystems) then they must match.
+ */
+ if ((opts.subsys_mask || opts.none) &&
+ (opts.subsys_mask != root->subsys_mask)) {
+ if (!name_match)
+ continue;
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+
+ if (root->flags ^ opts.flags)
+ pr_warn("new mount options do not match the existing superblock, will be ignored\n");
+
+ /*
+ * We want to reuse @root whose lifetime is governed by its
+ * ->cgrp. Let's check whether @root is alive and keep it
+ * that way. As cgroup_kill_sb() can happen anytime, we
+ * want to block it by pinning the sb so that @root doesn't
+ * get killed before mount is complete.
+ *
+ * With the sb pinned, tryget_live can reliably indicate
+ * whether @root can be reused. If it's being killed,
+ * drain it. We can use wait_queue for the wait but this
+ * path is super cold. Let's just sleep a bit and retry.
+ */
+ pinned_sb = kernfs_pin_sb(root->kf_root, NULL);
+ if (IS_ERR(pinned_sb) ||
+ !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {
+ mutex_unlock(&cgroup_mutex);
+ if (!IS_ERR_OR_NULL(pinned_sb))
+ deactivate_super(pinned_sb);
+ msleep(10);
+ ret = restart_syscall();
+ goto out_free;
+ }
+
+ ret = 0;
+ goto out_unlock;
+ }
+
+ /*
+ * No such thing, create a new one. name= matching without subsys
+ * specification is allowed for already existing hierarchies but we
+ * can't create new one without subsys specification.
+ */
+ if (!opts.subsys_mask && !opts.none) {
+ ret = -EINVAL;
+ goto out_unlock;
+ }
+
+ /* Hierarchies may only be created in the initial cgroup namespace. */
+ if (ns != &init_cgroup_ns) {
+ ret = -EPERM;
+ goto out_unlock;
+ }
+
+ root = kzalloc(sizeof(*root), GFP_KERNEL);
+ if (!root) {
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ init_cgroup_root(root, &opts);
+
+ ret = cgroup_setup_root(root, opts.subsys_mask);
+ if (ret)
+ cgroup_free_root(root);
+
+out_unlock:
+ mutex_unlock(&cgroup_mutex);
+out_free:
+ kfree(opts.release_agent);
+ kfree(opts.name);
+
+ if (ret) {
+ put_cgroup_ns(ns);
+ return ERR_PTR(ret);
+ }
+out_mount:
+ dentry = kernfs_mount(fs_type, flags, root->kf_root,
+ is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC,
+ &new_sb);
+
+ /*
+ * In non-init cgroup namespace, instead of root cgroup's
+ * dentry, we return the dentry corresponding to the
+ * cgroupns->root_cgrp.
+ */
+ if (!IS_ERR(dentry) && ns != &init_cgroup_ns) {
+ struct dentry *nsdentry;
+ struct cgroup *cgrp;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_irq(&css_set_lock);
+
+ cgrp = cset_cgroup_from_root(ns->root_cset, root);
+
+ spin_unlock_irq(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+
+ nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb);
+ dput(dentry);
+ dentry = nsdentry;
+ }
+
+ if (IS_ERR(dentry) || !new_sb)
+ cgroup_put(&root->cgrp);
+
+ /*
+ * If @pinned_sb, we're reusing an existing root and holding an
+ * extra ref on its sb. Mount is complete. Put the extra ref.
+ */
+ if (pinned_sb) {
+ WARN_ON(new_sb);
+ deactivate_super(pinned_sb);
+ }
+
+ put_cgroup_ns(ns);
+ return dentry;
+}
+
+static void cgroup_kill_sb(struct super_block *sb)
+{
+ struct kernfs_root *kf_root = kernfs_root_from_sb(sb);
+ struct cgroup_root *root = cgroup_root_from_kf(kf_root);
+
+ /*
+ * If @root doesn't have any mounts or children, start killing it.
+ * This prevents new mounts by disabling percpu_ref_tryget_live().
+ * cgroup_mount() may wait for @root's release.
+ *
+ * And don't kill the default root.
+ */
+ if (!list_empty(&root->cgrp.self.children) ||
+ root == &cgrp_dfl_root)
+ cgroup_put(&root->cgrp);
+ else
+ percpu_ref_kill(&root->cgrp.self.refcnt);
+
+ kernfs_kill_sb(sb);
+}
+
+static struct file_system_type cgroup_fs_type = {
+ .name = "cgroup",
+ .mount = cgroup_mount,
+ .kill_sb = cgroup_kill_sb,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+
+static struct file_system_type cgroup2_fs_type = {
+ .name = "cgroup2",
+ .mount = cgroup_mount,
+ .kill_sb = cgroup_kill_sb,
+ .fs_flags = FS_USERNS_MOUNT,
+};
+
+static int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns)
+{
+ struct cgroup *root = cset_cgroup_from_root(ns->root_cset, cgrp->root);
+
+ return kernfs_path_from_node(cgrp->kn, root->kn, buf, buflen);
+}
+
+int cgroup_path_ns(struct cgroup *cgrp, char *buf, size_t buflen,
+ struct cgroup_namespace *ns)
+{
+ int ret;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_irq(&css_set_lock);
+
+ ret = cgroup_path_ns_locked(cgrp, buf, buflen, ns);
+
+ spin_unlock_irq(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cgroup_path_ns);
+
+/**
+ * task_cgroup_path - cgroup path of a task in the first cgroup hierarchy
+ * @task: target task
+ * @buf: the buffer to write the path into
+ * @buflen: the length of the buffer
+ *
+ * Determine @task's cgroup on the first (the one with the lowest non-zero
+ * hierarchy_id) cgroup hierarchy and copy its path into @buf. This
+ * function grabs cgroup_mutex and shouldn't be used inside locks used by
+ * cgroup controller callbacks.
+ *
+ * Return value is the same as kernfs_path().
+ */
+int task_cgroup_path(struct task_struct *task, char *buf, size_t buflen)
+{
+ struct cgroup_root *root;
+ struct cgroup *cgrp;
+ int hierarchy_id = 1;
+ int ret;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_irq(&css_set_lock);
+
+ root = idr_get_next(&cgroup_hierarchy_idr, &hierarchy_id);
+
+ if (root) {
+ cgrp = task_cgroup_from_root(task, root);
+ ret = cgroup_path_ns_locked(cgrp, buf, buflen, &init_cgroup_ns);
+ } else {
+ /* if no hierarchy exists, everyone is in "/" */
+ ret = strlcpy(buf, "/", buflen);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(task_cgroup_path);
+
+/* used to track tasks and other necessary states during migration */
+struct cgroup_taskset {
+ /* the src and dst cset list running through cset->mg_node */
+ struct list_head src_csets;
+ struct list_head dst_csets;
+
+ /* the subsys currently being processed */
+ int ssid;
+
+ /*
+ * Fields for cgroup_taskset_*() iteration.
+ *
+ * Before migration is committed, the target migration tasks are on
+ * ->mg_tasks of the csets on ->src_csets. After, on ->mg_tasks of
+ * the csets on ->dst_csets. ->csets point to either ->src_csets
+ * or ->dst_csets depending on whether migration is committed.
+ *
+ * ->cur_csets and ->cur_task point to the current task position
+ * during iteration.
+ */
+ struct list_head *csets;
+ struct css_set *cur_cset;
+ struct task_struct *cur_task;
+};
+
+#define CGROUP_TASKSET_INIT(tset) (struct cgroup_taskset){ \
+ .src_csets = LIST_HEAD_INIT(tset.src_csets), \
+ .dst_csets = LIST_HEAD_INIT(tset.dst_csets), \
+ .csets = &tset.src_csets, \
+}
+
+/**
+ * cgroup_taskset_add - try to add a migration target task to a taskset
+ * @task: target task
+ * @tset: target taskset
+ *
+ * Add @task, which is a migration target, to @tset. This function becomes
+ * noop if @task doesn't need to be migrated. @task's css_set should have
+ * been added as a migration source and @task->cg_list will be moved from
+ * the css_set's tasks list to mg_tasks one.
+ */
+static void cgroup_taskset_add(struct task_struct *task,
+ struct cgroup_taskset *tset)
+{
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /* @task either already exited or can't exit until the end */
+ if (task->flags & PF_EXITING)
+ return;
+
+ /* leave @task alone if post_fork() hasn't linked it yet */
+ if (list_empty(&task->cg_list))
+ return;
+
+ cset = task_css_set(task);
+ if (!cset->mg_src_cgrp)
+ return;
+
+ list_move_tail(&task->cg_list, &cset->mg_tasks);
+ if (list_empty(&cset->mg_node))
+ list_add_tail(&cset->mg_node, &tset->src_csets);
+ if (list_empty(&cset->mg_dst_cset->mg_node))
+ list_move_tail(&cset->mg_dst_cset->mg_node,
+ &tset->dst_csets);
+}
+
+/**
+ * cgroup_taskset_first - reset taskset and return the first task
+ * @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
+ *
+ * @tset iteration is initialized and the first task is returned.
+ */
+struct task_struct *cgroup_taskset_first(struct cgroup_taskset *tset,
+ struct cgroup_subsys_state **dst_cssp)
+{
+ tset->cur_cset = list_first_entry(tset->csets, struct css_set, mg_node);
+ tset->cur_task = NULL;
+
+ return cgroup_taskset_next(tset, dst_cssp);
+}
+
+/**
+ * cgroup_taskset_next - iterate to the next task in taskset
+ * @tset: taskset of interest
+ * @dst_cssp: output variable for the destination css
+ *
+ * Return the next task in @tset. Iteration must have been initialized
+ * with cgroup_taskset_first().
+ */
+struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
+ struct cgroup_subsys_state **dst_cssp)
+{
+ struct css_set *cset = tset->cur_cset;
+ struct task_struct *task = tset->cur_task;
+
+ while (&cset->mg_node != tset->csets) {
+ if (!task)
+ task = list_first_entry(&cset->mg_tasks,
+ struct task_struct, cg_list);
+ else
+ task = list_next_entry(task, cg_list);
+
+ if (&task->cg_list != &cset->mg_tasks) {
+ tset->cur_cset = cset;
+ tset->cur_task = task;
+
+ /*
+ * This function may be called both before and
+ * after cgroup_taskset_migrate(). The two cases
+ * can be distinguished by looking at whether @cset
+ * has its ->mg_dst_cset set.
+ */
+ if (cset->mg_dst_cset)
+ *dst_cssp = cset->mg_dst_cset->subsys[tset->ssid];
+ else
+ *dst_cssp = cset->subsys[tset->ssid];
+
+ return task;
+ }
+
+ cset = list_next_entry(cset, mg_node);
+ task = NULL;
+ }
+
+ return NULL;
+}
+
+/**
+ * cgroup_taskset_migrate - migrate a taskset
+ * @tset: taget taskset
+ * @root: cgroup root the migration is taking place on
+ *
+ * Migrate tasks in @tset as setup by migration preparation functions.
+ * This function fails iff one of the ->can_attach callbacks fails and
+ * guarantees that either all or none of the tasks in @tset are migrated.
+ * @tset is consumed regardless of success.
+ */
+static int cgroup_taskset_migrate(struct cgroup_taskset *tset,
+ struct cgroup_root *root)
+{
+ struct cgroup_subsys *ss;
+ struct task_struct *task, *tmp_task;
+ struct css_set *cset, *tmp_cset;
+ int ssid, failed_ssid, ret;
+
+ /* methods shouldn't be called if no task is actually migrating */
+ if (list_empty(&tset->src_csets))
+ return 0;
+
+ /* check that we can legitimately attach to the cgroup */
+ do_each_subsys_mask(ss, ssid, root->subsys_mask) {
+ if (ss->can_attach) {
+ tset->ssid = ssid;
+ ret = ss->can_attach(tset);
+ if (ret) {
+ failed_ssid = ssid;
+ goto out_cancel_attach;
+ }
+ }
+ } while_each_subsys_mask();
+
+ /*
+ * Now that we're guaranteed success, proceed to move all tasks to
+ * the new cgroup. There are no failure cases after here, so this
+ * is the commit point.
+ */
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(cset, &tset->src_csets, mg_node) {
+ list_for_each_entry_safe(task, tmp_task, &cset->mg_tasks, cg_list) {
+ struct css_set *from_cset = task_css_set(task);
+ struct css_set *to_cset = cset->mg_dst_cset;
+
+ get_css_set(to_cset);
+ css_set_move_task(task, from_cset, to_cset, true);
+ put_css_set_locked(from_cset);
+ }
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ /*
+ * Migration is committed, all target tasks are now on dst_csets.
+ * Nothing is sensitive to fork() after this point. Notify
+ * controllers that migration is complete.
+ */
+ tset->csets = &tset->dst_csets;
+
+ do_each_subsys_mask(ss, ssid, root->subsys_mask) {
+ if (ss->attach) {
+ tset->ssid = ssid;
+ ss->attach(tset);
+ }
+ } while_each_subsys_mask();
+
+ ret = 0;
+ goto out_release_tset;
+
+out_cancel_attach:
+ do_each_subsys_mask(ss, ssid, root->subsys_mask) {
+ if (ssid == failed_ssid)
+ break;
+ if (ss->cancel_attach) {
+ tset->ssid = ssid;
+ ss->cancel_attach(tset);
+ }
+ } while_each_subsys_mask();
+out_release_tset:
+ spin_lock_irq(&css_set_lock);
+ list_splice_init(&tset->dst_csets, &tset->src_csets);
+ list_for_each_entry_safe(cset, tmp_cset, &tset->src_csets, mg_node) {
+ list_splice_tail_init(&cset->mg_tasks, &cset->tasks);
+ list_del_init(&cset->mg_node);
+ }
+ spin_unlock_irq(&css_set_lock);
+ return ret;
+}
+
+/**
+ * cgroup_may_migrate_to - verify whether a cgroup can be migration destination
+ * @dst_cgrp: destination cgroup to test
+ *
+ * On the default hierarchy, except for the root, subtree_control must be
+ * zero for migration destination cgroups with tasks so that child cgroups
+ * don't compete against tasks.
+ */
+static bool cgroup_may_migrate_to(struct cgroup *dst_cgrp)
+{
+ return !cgroup_on_dfl(dst_cgrp) || !cgroup_parent(dst_cgrp) ||
+ !dst_cgrp->subtree_control;
+}
+
+/**
+ * cgroup_migrate_finish - cleanup after attach
+ * @preloaded_csets: list of preloaded css_sets
+ *
+ * Undo cgroup_migrate_add_src() and cgroup_migrate_prepare_dst(). See
+ * those functions for details.
+ */
+static void cgroup_migrate_finish(struct list_head *preloaded_csets)
+{
+ struct css_set *cset, *tmp_cset;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry_safe(cset, tmp_cset, preloaded_csets, mg_preload_node) {
+ cset->mg_src_cgrp = NULL;
+ cset->mg_dst_cgrp = NULL;
+ cset->mg_dst_cset = NULL;
+ list_del_init(&cset->mg_preload_node);
+ put_css_set_locked(cset);
+ }
+ spin_unlock_irq(&css_set_lock);
+}
+
+/**
+ * cgroup_migrate_add_src - add a migration source css_set
+ * @src_cset: the source css_set to add
+ * @dst_cgrp: the destination cgroup
+ * @preloaded_csets: list of preloaded css_sets
+ *
+ * Tasks belonging to @src_cset are about to be migrated to @dst_cgrp. Pin
+ * @src_cset and add it to @preloaded_csets, which should later be cleaned
+ * up by cgroup_migrate_finish().
+ *
+ * This function may be called without holding cgroup_threadgroup_rwsem
+ * even if the target is a process. Threads may be created and destroyed
+ * but as long as cgroup_mutex is not dropped, no new css_set can be put
+ * into play and the preloaded css_sets are guaranteed to cover all
+ * migrations.
+ */
+static void cgroup_migrate_add_src(struct css_set *src_cset,
+ struct cgroup *dst_cgrp,
+ struct list_head *preloaded_csets)
+{
+ struct cgroup *src_cgrp;
+
+ lockdep_assert_held(&cgroup_mutex);
+ lockdep_assert_held(&css_set_lock);
+
+ /*
+ * If ->dead, @src_set is associated with one or more dead cgroups
+ * and doesn't contain any migratable tasks. Ignore it early so
+ * that the rest of migration path doesn't get confused by it.
+ */
+ if (src_cset->dead)
+ return;
+
+ src_cgrp = cset_cgroup_from_root(src_cset, dst_cgrp->root);
+
+ if (!list_empty(&src_cset->mg_preload_node))
+ return;
+
+ WARN_ON(src_cset->mg_src_cgrp);
+ WARN_ON(src_cset->mg_dst_cgrp);
+ WARN_ON(!list_empty(&src_cset->mg_tasks));
+ WARN_ON(!list_empty(&src_cset->mg_node));
+
+ src_cset->mg_src_cgrp = src_cgrp;
+ src_cset->mg_dst_cgrp = dst_cgrp;
+ get_css_set(src_cset);
+ list_add(&src_cset->mg_preload_node, preloaded_csets);
+}
+
+/**
+ * cgroup_migrate_prepare_dst - prepare destination css_sets for migration
+ * @preloaded_csets: list of preloaded source css_sets
+ *
+ * Tasks are about to be moved and all the source css_sets have been
+ * preloaded to @preloaded_csets. This function looks up and pins all
+ * destination css_sets, links each to its source, and append them to
+ * @preloaded_csets.
+ *
+ * This function must be called after cgroup_migrate_add_src() has been
+ * called on each migration source css_set. After migration is performed
+ * using cgroup_migrate(), cgroup_migrate_finish() must be called on
+ * @preloaded_csets.
+ */
+static int cgroup_migrate_prepare_dst(struct list_head *preloaded_csets)
+{
+ LIST_HEAD(csets);
+ struct css_set *src_cset, *tmp_cset;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* look up the dst cset for each src cset and link it to src */
+ list_for_each_entry_safe(src_cset, tmp_cset, preloaded_csets, mg_preload_node) {
+ struct css_set *dst_cset;
+
+ dst_cset = find_css_set(src_cset, src_cset->mg_dst_cgrp);
+ if (!dst_cset)
+ goto err;
+
+ WARN_ON_ONCE(src_cset->mg_dst_cset || dst_cset->mg_dst_cset);
+
+ /*
+ * If src cset equals dst, it's noop. Drop the src.
+ * cgroup_migrate() will skip the cset too. Note that we
+ * can't handle src == dst as some nodes are used by both.
+ */
+ if (src_cset == dst_cset) {
+ src_cset->mg_src_cgrp = NULL;
+ src_cset->mg_dst_cgrp = NULL;
+ list_del_init(&src_cset->mg_preload_node);
+ put_css_set(src_cset);
+ put_css_set(dst_cset);
+ continue;
+ }
+
+ src_cset->mg_dst_cset = dst_cset;
+
+ if (list_empty(&dst_cset->mg_preload_node))
+ list_add(&dst_cset->mg_preload_node, &csets);
+ else
+ put_css_set(dst_cset);
+ }
+
+ list_splice_tail(&csets, preloaded_csets);
+ return 0;
+err:
+ cgroup_migrate_finish(&csets);
+ return -ENOMEM;
+}
+
+/**
+ * cgroup_migrate - migrate a process or task to a cgroup
+ * @leader: the leader of the process or the task to migrate
+ * @threadgroup: whether @leader points to the whole process or a single task
+ * @root: cgroup root migration is taking place on
+ *
+ * Migrate a process or task denoted by @leader. If migrating a process,
+ * the caller must be holding cgroup_threadgroup_rwsem. The caller is also
+ * responsible for invoking cgroup_migrate_add_src() and
+ * cgroup_migrate_prepare_dst() on the targets before invoking this
+ * function and following up with cgroup_migrate_finish().
+ *
+ * As long as a controller's ->can_attach() doesn't fail, this function is
+ * guaranteed to succeed. This means that, excluding ->can_attach()
+ * failure, when migrating multiple targets, the success or failure can be
+ * decided for all targets by invoking group_migrate_prepare_dst() before
+ * actually starting migrating.
+ */
+static int cgroup_migrate(struct task_struct *leader, bool threadgroup,
+ struct cgroup_root *root)
+{
+ struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
+ struct task_struct *task;
+
+ /*
+ * Prevent freeing of tasks while we take a snapshot. Tasks that are
+ * already PF_EXITING could be freed from underneath us unless we
+ * take an rcu_read_lock.
+ */
+ spin_lock_irq(&css_set_lock);
+ rcu_read_lock();
+ task = leader;
+ do {
+ cgroup_taskset_add(task, &tset);
+ if (!threadgroup)
+ break;
+ } while_each_thread(leader, task);
+ rcu_read_unlock();
+ spin_unlock_irq(&css_set_lock);
+
+ return cgroup_taskset_migrate(&tset, root);
+}
+
+/**
+ * cgroup_attach_task - attach a task or a whole threadgroup to a cgroup
+ * @dst_cgrp: the cgroup to attach to
+ * @leader: the task or the leader of the threadgroup to be attached
+ * @threadgroup: attach the whole threadgroup?
+ *
+ * Call holding cgroup_mutex and cgroup_threadgroup_rwsem.
+ */
+static int cgroup_attach_task(struct cgroup *dst_cgrp,
+ struct task_struct *leader, bool threadgroup)
+{
+ LIST_HEAD(preloaded_csets);
+ struct task_struct *task;
+ int ret;
+
+ if (!cgroup_may_migrate_to(dst_cgrp))
+ return -EBUSY;
+
+ /* look up all src csets */
+ spin_lock_irq(&css_set_lock);
+ rcu_read_lock();
+ task = leader;
+ do {
+ cgroup_migrate_add_src(task_css_set(task), dst_cgrp,
+ &preloaded_csets);
+ if (!threadgroup)
+ break;
+ } while_each_thread(leader, task);
+ rcu_read_unlock();
+ spin_unlock_irq(&css_set_lock);
+
+ /* prepare dst csets and commit */
+ ret = cgroup_migrate_prepare_dst(&preloaded_csets);
+ if (!ret)
+ ret = cgroup_migrate(leader, threadgroup, dst_cgrp->root);
+
+ cgroup_migrate_finish(&preloaded_csets);
+
+ if (!ret)
+ trace_cgroup_attach_task(dst_cgrp, leader, threadgroup);
+
+ return ret;
+}
+
+static int cgroup_procs_write_permission(struct task_struct *task,
+ struct cgroup *dst_cgrp,
+ struct kernfs_open_file *of)
+{
+ const struct cred *cred = current_cred();
+ const struct cred *tcred = get_task_cred(task);
+ int ret = 0;
+
+ /*
+ * even if we're attaching all tasks in the thread group, we only
+ * need to check permissions on one of them.
+ */
+ if (!uid_eq(cred->euid, GLOBAL_ROOT_UID) &&
+ !uid_eq(cred->euid, tcred->uid) &&
+ !uid_eq(cred->euid, tcred->suid))
+ ret = -EACCES;
+
+ if (!ret && cgroup_on_dfl(dst_cgrp)) {
+ struct super_block *sb = of->file->f_path.dentry->d_sb;
+ struct cgroup *cgrp;
+ struct inode *inode;
+
+ spin_lock_irq(&css_set_lock);
+ cgrp = task_cgroup_from_root(task, &cgrp_dfl_root);
+ spin_unlock_irq(&css_set_lock);
+
+ while (!cgroup_is_descendant(dst_cgrp, cgrp))
+ cgrp = cgroup_parent(cgrp);
+
+ ret = -ENOMEM;
+ inode = kernfs_get_inode(sb, cgrp->procs_file.kn);
+ if (inode) {
+ ret = inode_permission(inode, MAY_WRITE);
+ iput(inode);
+ }
+ }
+
+ put_cred(tcred);
+ return ret;
+}
+
+/*
+ * Find the task_struct of the task to attach by vpid and pass it along to the
+ * function to attach either it or all tasks in its threadgroup. Will lock
+ * cgroup_mutex and threadgroup.
+ */
+static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off, bool threadgroup)
+{
+ struct task_struct *tsk;
+ struct cgroup_subsys *ss;
+ struct cgroup *cgrp;
+ pid_t pid;
+ int ssid, ret;
+
+ if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
+ return -EINVAL;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+ rcu_read_lock();
+ if (pid) {
+ tsk = find_task_by_vpid(pid);
+ if (!tsk) {
+ ret = -ESRCH;
+ goto out_unlock_rcu;
+ }
+ } else {
+ tsk = current;
+ }
+
+ if (threadgroup)
+ tsk = tsk->group_leader;
+
+ /*
+ * Workqueue threads may acquire PF_NO_SETAFFINITY and become
+ * trapped in a cpuset, or RT worker may be born in a cgroup
+ * with no rt_runtime allocated. Just say no.
+ */
+ if (tsk == kthreadd_task || (tsk->flags & PF_NO_SETAFFINITY)) {
+ ret = -EINVAL;
+ goto out_unlock_rcu;
+ }
+
+ get_task_struct(tsk);
+ rcu_read_unlock();
+
+ ret = cgroup_procs_write_permission(tsk, cgrp, of);
+ if (!ret)
+ ret = cgroup_attach_task(cgrp, tsk, threadgroup);
+
+ put_task_struct(tsk);
+ goto out_unlock_threadgroup;
+
+out_unlock_rcu:
+ rcu_read_unlock();
+out_unlock_threadgroup:
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ for_each_subsys(ss, ssid)
+ if (ss->post_attach)
+ ss->post_attach();
+ cgroup_kn_unlock(of->kn);
+ return ret ?: nbytes;
+}
+
+/**
+ * cgroup_attach_task_all - attach task 'tsk' to all cgroups of task 'from'
+ * @from: attach to all cgroups of a given task
+ * @tsk: the task to be attached
+ */
+int cgroup_attach_task_all(struct task_struct *from, struct task_struct *tsk)
+{
+ struct cgroup_root *root;
+ int retval = 0;
+
+ mutex_lock(&cgroup_mutex);
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+ for_each_root(root) {
+ struct cgroup *from_cgrp;
+
+ if (root == &cgrp_dfl_root)
+ continue;
+
+ spin_lock_irq(&css_set_lock);
+ from_cgrp = task_cgroup_from_root(from, root);
+ spin_unlock_irq(&css_set_lock);
+
+ retval = cgroup_attach_task(from_cgrp, tsk, false);
+ if (retval)
+ break;
+ }
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ mutex_unlock(&cgroup_mutex);
+
+ return retval;
+}
+EXPORT_SYMBOL_GPL(cgroup_attach_task_all);
+
+static ssize_t cgroup_tasks_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup_procs_write(of, buf, nbytes, off, false);
+}
+
+static ssize_t cgroup_procs_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ return __cgroup_procs_write(of, buf, nbytes, off, true);
+}
+
+static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp;
+
+ BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX);
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENODEV;
+ spin_lock(&release_agent_path_lock);
+ strlcpy(cgrp->root->release_agent_path, strstrip(buf),
+ sizeof(cgrp->root->release_agent_path));
+ spin_unlock(&release_agent_path_lock);
+ cgroup_kn_unlock(of->kn);
+ return nbytes;
+}
+
+static int cgroup_release_agent_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ spin_lock(&release_agent_path_lock);
+ seq_puts(seq, cgrp->root->release_agent_path);
+ spin_unlock(&release_agent_path_lock);
+ seq_putc(seq, '\n');
+ return 0;
+}
+
+static int cgroup_sane_behavior_show(struct seq_file *seq, void *v)
+{
+ seq_puts(seq, "0\n");
+ return 0;
+}
+
+static void cgroup_print_ss_mask(struct seq_file *seq, u16 ss_mask)
+{
+ struct cgroup_subsys *ss;
+ bool printed = false;
+ int ssid;
+
+ do_each_subsys_mask(ss, ssid, ss_mask) {
+ if (printed)
+ seq_putc(seq, ' ');
+ seq_printf(seq, "%s", ss->name);
+ printed = true;
+ } while_each_subsys_mask();
+ if (printed)
+ seq_putc(seq, '\n');
+}
+
+/* show controllers which are enabled from the parent */
+static int cgroup_controllers_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ cgroup_print_ss_mask(seq, cgroup_control(cgrp));
+ return 0;
+}
+
+/* show controllers which are enabled for a given cgroup's children */
+static int cgroup_subtree_control_show(struct seq_file *seq, void *v)
+{
+ struct cgroup *cgrp = seq_css(seq)->cgroup;
+
+ cgroup_print_ss_mask(seq, cgrp->subtree_control);
+ return 0;
+}
+
+/**
+ * cgroup_update_dfl_csses - update css assoc of a subtree in default hierarchy
+ * @cgrp: root of the subtree to update csses for
+ *
+ * @cgrp's control masks have changed and its subtree's css associations
+ * need to be updated accordingly. This function looks up all css_sets
+ * which are attached to the subtree, creates the matching updated css_sets
+ * and migrates the tasks to the new ones.
+ */
+static int cgroup_update_dfl_csses(struct cgroup *cgrp)
+{
+ LIST_HEAD(preloaded_csets);
+ struct cgroup_taskset tset = CGROUP_TASKSET_INIT(tset);
+ struct cgroup_subsys_state *d_css;
+ struct cgroup *dsct;
+ struct css_set *src_cset;
+ int ret;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+
+ /* look up all csses currently attached to @cgrp's subtree */
+ spin_lock_irq(&css_set_lock);
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ struct cgrp_cset_link *link;
+
+ list_for_each_entry(link, &dsct->cset_links, cset_link)
+ cgroup_migrate_add_src(link->cset, dsct,
+ &preloaded_csets);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ /* NULL dst indicates self on default hierarchy */
+ ret = cgroup_migrate_prepare_dst(&preloaded_csets);
+ if (ret)
+ goto out_finish;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(src_cset, &preloaded_csets, mg_preload_node) {
+ struct task_struct *task, *ntask;
+
+ /* src_csets precede dst_csets, break on the first dst_cset */
+ if (!src_cset->mg_src_cgrp)
+ break;
+
+ /* all tasks in src_csets need to be migrated */
+ list_for_each_entry_safe(task, ntask, &src_cset->tasks, cg_list)
+ cgroup_taskset_add(task, &tset);
+ }
+ spin_unlock_irq(&css_set_lock);
+
+ ret = cgroup_taskset_migrate(&tset, cgrp->root);
+out_finish:
+ cgroup_migrate_finish(&preloaded_csets);
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ return ret;
+}
+
+/**
+ * cgroup_lock_and_drain_offline - lock cgroup_mutex and drain offlined csses
+ * @cgrp: root of the target subtree
+ *
+ * Because css offlining is asynchronous, userland may try to re-enable a
+ * controller while the previous css is still around. This function grabs
+ * cgroup_mutex and drains the previous css instances of @cgrp's subtree.
+ */
+static void cgroup_lock_and_drain_offline(struct cgroup *cgrp)
+ __acquires(&cgroup_mutex)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+restart:
+ mutex_lock(&cgroup_mutex);
+
+ cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+ DEFINE_WAIT(wait);
+
+ if (!css || !percpu_ref_is_dying(&css->refcnt))
+ continue;
+
+ cgroup_get(dsct);
+ prepare_to_wait(&dsct->offline_waitq, &wait,
+ TASK_UNINTERRUPTIBLE);
+
+ mutex_unlock(&cgroup_mutex);
+ schedule();
+ finish_wait(&dsct->offline_waitq, &wait);
+
+ cgroup_put(dsct);
+ goto restart;
+ }
+ }
+}
+
+/**
+ * cgroup_save_control - save control masks of a subtree
+ * @cgrp: root of the target subtree
+ *
+ * Save ->subtree_control and ->subtree_ss_mask to the respective old_
+ * prefixed fields for @cgrp's subtree including @cgrp itself.
+ */
+static void cgroup_save_control(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ dsct->old_subtree_control = dsct->subtree_control;
+ dsct->old_subtree_ss_mask = dsct->subtree_ss_mask;
+ }
+}
+
+/**
+ * cgroup_propagate_control - refresh control masks of a subtree
+ * @cgrp: root of the target subtree
+ *
+ * For @cgrp and its subtree, ensure ->subtree_ss_mask matches
+ * ->subtree_control and propagate controller availability through the
+ * subtree so that descendants don't have unavailable controllers enabled.
+ */
+static void cgroup_propagate_control(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ dsct->subtree_control &= cgroup_control(dsct);
+ dsct->subtree_ss_mask =
+ cgroup_calc_subtree_ss_mask(dsct->subtree_control,
+ cgroup_ss_mask(dsct));
+ }
+}
+
+/**
+ * cgroup_restore_control - restore control masks of a subtree
+ * @cgrp: root of the target subtree
+ *
+ * Restore ->subtree_control and ->subtree_ss_mask from the respective old_
+ * prefixed fields for @cgrp's subtree including @cgrp itself.
+ */
+static void cgroup_restore_control(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+
+ cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ dsct->subtree_control = dsct->old_subtree_control;
+ dsct->subtree_ss_mask = dsct->old_subtree_ss_mask;
+ }
+}
+
+static bool css_visible(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys *ss = css->ss;
+ struct cgroup *cgrp = css->cgroup;
+
+ if (cgroup_control(cgrp) & (1 << ss->id))
+ return true;
+ if (!(cgroup_ss_mask(cgrp) & (1 << ss->id)))
+ return false;
+ return cgroup_on_dfl(cgrp) && ss->implicit_on_dfl;
+}
+
+/**
+ * cgroup_apply_control_enable - enable or show csses according to control
+ * @cgrp: root of the target subtree
+ *
+ * Walk @cgrp's subtree and create new csses or make the existing ones
+ * visible. A css is created invisible if it's being implicitly enabled
+ * through dependency. An invisible css is made visible when the userland
+ * explicitly enables it.
+ *
+ * Returns 0 on success, -errno on failure. On failure, csses which have
+ * been processed already aren't cleaned up. The caller is responsible for
+ * cleaning up with cgroup_apply_control_disble().
+ */
+static int cgroup_apply_control_enable(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ struct cgroup_subsys *ss;
+ int ssid, ret;
+
+ cgroup_for_each_live_descendant_pre(dsct, d_css, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+
+ WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt));
+
+ if (!(cgroup_ss_mask(dsct) & (1 << ss->id)))
+ continue;
+
+ if (!css) {
+ css = css_create(dsct, ss);
+ if (IS_ERR(css))
+ return PTR_ERR(css);
+ }
+
+ if (css_visible(css)) {
+ ret = css_populate_dir(css);
+ if (ret)
+ return ret;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/**
+ * cgroup_apply_control_disable - kill or hide csses according to control
+ * @cgrp: root of the target subtree
+ *
+ * Walk @cgrp's subtree and kill and hide csses so that they match
+ * cgroup_ss_mask() and cgroup_visible_mask().
+ *
+ * A css is hidden when the userland requests it to be disabled while other
+ * subsystems are still depending on it. The css must not actively control
+ * resources and be in the vanilla state if it's made visible again later.
+ * Controllers which may be depended upon should provide ->css_reset() for
+ * this purpose.
+ */
+static void cgroup_apply_control_disable(struct cgroup *cgrp)
+{
+ struct cgroup *dsct;
+ struct cgroup_subsys_state *d_css;
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ cgroup_for_each_live_descendant_post(dsct, d_css, cgrp) {
+ for_each_subsys(ss, ssid) {
+ struct cgroup_subsys_state *css = cgroup_css(dsct, ss);
+
+ WARN_ON_ONCE(css && percpu_ref_is_dying(&css->refcnt));
+
+ if (!css)
+ continue;
+
+ if (css->parent &&
+ !(cgroup_ss_mask(dsct) & (1 << ss->id))) {
+ kill_css(css);
+ } else if (!css_visible(css)) {
+ css_clear_dir(css);
+ if (ss->css_reset)
+ ss->css_reset(css);
+ }
+ }
+ }
+}
+
+/**
+ * cgroup_apply_control - apply control mask updates to the subtree
+ * @cgrp: root of the target subtree
+ *
+ * subsystems can be enabled and disabled in a subtree using the following
+ * steps.
+ *
+ * 1. Call cgroup_save_control() to stash the current state.
+ * 2. Update ->subtree_control masks in the subtree as desired.
+ * 3. Call cgroup_apply_control() to apply the changes.
+ * 4. Optionally perform other related operations.
+ * 5. Call cgroup_finalize_control() to finish up.
+ *
+ * This function implements step 3 and propagates the mask changes
+ * throughout @cgrp's subtree, updates csses accordingly and perform
+ * process migrations.
+ */
+static int cgroup_apply_control(struct cgroup *cgrp)
+{
+ int ret;
+
+ cgroup_propagate_control(cgrp);
+
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ return ret;
+
+ /*
+ * At this point, cgroup_e_css() results reflect the new csses
+ * making the following cgroup_update_dfl_csses() properly update
+ * css associations of all tasks in the subtree.
+ */
+ ret = cgroup_update_dfl_csses(cgrp);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+/**
+ * cgroup_finalize_control - finalize control mask update
+ * @cgrp: root of the target subtree
+ * @ret: the result of the update
+ *
+ * Finalize control mask update. See cgroup_apply_control() for more info.
+ */
+static void cgroup_finalize_control(struct cgroup *cgrp, int ret)
+{
+ if (ret) {
+ cgroup_restore_control(cgrp);
+ cgroup_propagate_control(cgrp);
+ }
+
+ cgroup_apply_control_disable(cgrp);
+}
+
+/* change the enabled child controllers for a cgroup in the default hierarchy */
+static ssize_t cgroup_subtree_control_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes,
+ loff_t off)
+{
+ u16 enable = 0, disable = 0;
+ struct cgroup *cgrp, *child;
+ struct cgroup_subsys *ss;
+ char *tok;
+ int ssid, ret;
+
+ /*
+ * Parse input - space separated list of subsystem names prefixed
+ * with either + or -.
+ */
+ buf = strstrip(buf);
+ while ((tok = strsep(&buf, " "))) {
+ if (tok[0] == '\0')
+ continue;
+ do_each_subsys_mask(ss, ssid, ~cgrp_dfl_inhibit_ss_mask) {
+ if (!cgroup_ssid_enabled(ssid) ||
+ strcmp(tok + 1, ss->name))
+ continue;
+
+ if (*tok == '+') {
+ enable |= 1 << ssid;
+ disable &= ~(1 << ssid);
+ } else if (*tok == '-') {
+ disable |= 1 << ssid;
+ enable &= ~(1 << ssid);
+ } else {
+ return -EINVAL;
+ }
+ break;
+ } while_each_subsys_mask();
+ if (ssid == CGROUP_SUBSYS_COUNT)
+ return -EINVAL;
+ }
+
+ cgrp = cgroup_kn_lock_live(of->kn, true);
+ if (!cgrp)
+ return -ENODEV;
+
+ for_each_subsys(ss, ssid) {
+ if (enable & (1 << ssid)) {
+ if (cgrp->subtree_control & (1 << ssid)) {
+ enable &= ~(1 << ssid);
+ continue;
+ }
+
+ if (!(cgroup_control(cgrp) & (1 << ssid))) {
+ ret = -ENOENT;
+ goto out_unlock;
+ }
+ } else if (disable & (1 << ssid)) {
+ if (!(cgrp->subtree_control & (1 << ssid))) {
+ disable &= ~(1 << ssid);
+ continue;
+ }
+
+ /* a child has it enabled? */
+ cgroup_for_each_live_child(child, cgrp) {
+ if (child->subtree_control & (1 << ssid)) {
+ ret = -EBUSY;
+ goto out_unlock;
+ }
+ }
+ }
+ }
+
+ if (!enable && !disable) {
+ ret = 0;
+ goto out_unlock;
+ }
+
+ /*
+ * Except for the root, subtree_control must be zero for a cgroup
+ * with tasks so that child cgroups don't compete against tasks.
+ */
+ if (enable && cgroup_parent(cgrp)) {
+ struct cgrp_cset_link *link;
+
+ /*
+ * Because namespaces pin csets too, @cgrp->cset_links
+ * might not be empty even when @cgrp is empty. Walk and
+ * verify each cset.
+ */
+ spin_lock_irq(&css_set_lock);
+
+ ret = 0;
+ list_for_each_entry(link, &cgrp->cset_links, cset_link) {
+ if (css_set_populated(link->cset)) {
+ ret = -EBUSY;
+ break;
+ }
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ if (ret)
+ goto out_unlock;
+ }
+
+ /* save and update control masks and prepare csses */
+ cgroup_save_control(cgrp);
+
+ cgrp->subtree_control |= enable;
+ cgrp->subtree_control &= ~disable;
+
+ ret = cgroup_apply_control(cgrp);
+
+ cgroup_finalize_control(cgrp, ret);
+
+ kernfs_activate(cgrp->kn);
+ ret = 0;
+out_unlock:
+ cgroup_kn_unlock(of->kn);
+ return ret ?: nbytes;
+}
+
+static int cgroup_events_show(struct seq_file *seq, void *v)
+{
+ seq_printf(seq, "populated %d\n",
+ cgroup_is_populated(seq_css(seq)->cgroup));
+ return 0;
+}
+
+static int cgroup_file_open(struct kernfs_open_file *of)
+{
+ struct cftype *cft = of->kn->priv;
+
+ if (cft->open)
+ return cft->open(of);
+ return 0;
+}
+
+static void cgroup_file_release(struct kernfs_open_file *of)
+{
+ struct cftype *cft = of->kn->priv;
+
+ if (cft->release)
+ cft->release(of);
+}
+
+static ssize_t cgroup_file_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup *cgrp = of->kn->parent->priv;
+ struct cftype *cft = of->kn->priv;
+ struct cgroup_subsys_state *css;
+ int ret;
+
+ if (cft->write)
+ return cft->write(of, buf, nbytes, off);
+
+ /*
+ * kernfs guarantees that a file isn't deleted with operations in
+ * flight, which means that the matching css is and stays alive and
+ * doesn't need to be pinned. The RCU locking is not necessary
+ * either. It's just for the convenience of using cgroup_css().
+ */
+ rcu_read_lock();
+ css = cgroup_css(cgrp, cft->ss);
+ rcu_read_unlock();
+
+ if (cft->write_u64) {
+ unsigned long long v;
+ ret = kstrtoull(buf, 0, &v);
+ if (!ret)
+ ret = cft->write_u64(css, cft, v);
+ } else if (cft->write_s64) {
+ long long v;
+ ret = kstrtoll(buf, 0, &v);
+ if (!ret)
+ ret = cft->write_s64(css, cft, v);
+ } else {
+ ret = -EINVAL;
+ }
+
+ return ret ?: nbytes;
+}
+
+static void *cgroup_seqfile_start(struct seq_file *seq, loff_t *ppos)
+{
+ return seq_cft(seq)->seq_start(seq, ppos);
+}
+
+static void *cgroup_seqfile_next(struct seq_file *seq, void *v, loff_t *ppos)
+{
+ return seq_cft(seq)->seq_next(seq, v, ppos);
+}
+
+static void cgroup_seqfile_stop(struct seq_file *seq, void *v)
+{
+ if (seq_cft(seq)->seq_stop)
+ seq_cft(seq)->seq_stop(seq, v);
+}
+
+static int cgroup_seqfile_show(struct seq_file *m, void *arg)
+{
+ struct cftype *cft = seq_cft(m);
+ struct cgroup_subsys_state *css = seq_css(m);
+
+ if (cft->seq_show)
+ return cft->seq_show(m, arg);
+
+ if (cft->read_u64)
+ seq_printf(m, "%llu\n", cft->read_u64(css, cft));
+ else if (cft->read_s64)
+ seq_printf(m, "%lld\n", cft->read_s64(css, cft));
+ else
+ return -EINVAL;
+ return 0;
+}
+
+static struct kernfs_ops cgroup_kf_single_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .open = cgroup_file_open,
+ .release = cgroup_file_release,
+ .write = cgroup_file_write,
+ .seq_show = cgroup_seqfile_show,
+};
+
+static struct kernfs_ops cgroup_kf_ops = {
+ .atomic_write_len = PAGE_SIZE,
+ .open = cgroup_file_open,
+ .release = cgroup_file_release,
+ .write = cgroup_file_write,
+ .seq_start = cgroup_seqfile_start,
+ .seq_next = cgroup_seqfile_next,
+ .seq_stop = cgroup_seqfile_stop,
+ .seq_show = cgroup_seqfile_show,
+};
+
+/*
+ * cgroup_rename - Only allow simple rename of directories in place.
+ */
+static int cgroup_rename(struct kernfs_node *kn, struct kernfs_node *new_parent,
+ const char *new_name_str)
+{
+ struct cgroup *cgrp = kn->priv;
+ int ret;
+
+ if (kernfs_type(kn) != KERNFS_DIR)
+ return -ENOTDIR;
+ if (kn->parent != new_parent)
+ return -EIO;
+
+ /*
+ * This isn't a proper migration and its usefulness is very
+ * limited. Disallow on the default hierarchy.
+ */
+ if (cgroup_on_dfl(cgrp))
+ return -EPERM;
+
+ /*
+ * We're gonna grab cgroup_mutex which nests outside kernfs
+ * active_ref. kernfs_rename() doesn't require active_ref
+ * protection. Break them before grabbing cgroup_mutex.
+ */
+ kernfs_break_active_protection(new_parent);
+ kernfs_break_active_protection(kn);
+
+ mutex_lock(&cgroup_mutex);
+
+ ret = kernfs_rename(kn, new_parent, new_name_str);
+ if (!ret)
+ trace_cgroup_rename(cgrp);
+
+ mutex_unlock(&cgroup_mutex);
+
+ kernfs_unbreak_active_protection(kn);
+ kernfs_unbreak_active_protection(new_parent);
+ return ret;
+}
+
+/* set uid and gid of cgroup dirs and files to that of the creator */
+static int cgroup_kn_set_ugid(struct kernfs_node *kn)
+{
+ struct iattr iattr = { .ia_valid = ATTR_UID | ATTR_GID,
+ .ia_uid = current_fsuid(),
+ .ia_gid = current_fsgid(), };
+
+ if (uid_eq(iattr.ia_uid, GLOBAL_ROOT_UID) &&
+ gid_eq(iattr.ia_gid, GLOBAL_ROOT_GID))
+ return 0;
+
+ return kernfs_setattr(kn, &iattr);
+}
+
+static int cgroup_add_file(struct cgroup_subsys_state *css, struct cgroup *cgrp,
+ struct cftype *cft)
+{
+ char name[CGROUP_FILE_NAME_MAX];
+ struct kernfs_node *kn;
+ struct lock_class_key *key = NULL;
+ int ret;
+
+#ifdef CONFIG_DEBUG_LOCK_ALLOC
+ key = &cft->lockdep_key;
+#endif
+ kn = __kernfs_create_file(cgrp->kn, cgroup_file_name(cgrp, cft, name),
+ cgroup_file_mode(cft), 0, cft->kf_ops, cft,
+ NULL, key);
+ if (IS_ERR(kn))
+ return PTR_ERR(kn);
+
+ ret = cgroup_kn_set_ugid(kn);
+ if (ret) {
+ kernfs_remove(kn);
+ return ret;
+ }
+
+ if (cft->file_offset) {
+ struct cgroup_file *cfile = (void *)css + cft->file_offset;
+
+ spin_lock_irq(&cgroup_file_kn_lock);
+ cfile->kn = kn;
+ spin_unlock_irq(&cgroup_file_kn_lock);
+ }
+
+ return 0;
+}
+
+/**
+ * cgroup_addrm_files - add or remove files to a cgroup directory
+ * @css: the target css
+ * @cgrp: the target cgroup (usually css->cgroup)
+ * @cfts: array of cftypes to be added
+ * @is_add: whether to add or remove
+ *
+ * Depending on @is_add, add or remove files defined by @cfts on @cgrp.
+ * For removals, this function never fails.
+ */
+static int cgroup_addrm_files(struct cgroup_subsys_state *css,
+ struct cgroup *cgrp, struct cftype cfts[],
+ bool is_add)
+{
+ struct cftype *cft, *cft_end = NULL;
+ int ret = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+restart:
+ for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
+ /* does cft->flags tell us to skip this file on @cgrp? */
+ if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
+ continue;
+ if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
+ continue;
+ if ((cft->flags & CFTYPE_NOT_ON_ROOT) && !cgroup_parent(cgrp))
+ continue;
+ if ((cft->flags & CFTYPE_ONLY_ON_ROOT) && cgroup_parent(cgrp))
+ continue;
+
+ if (is_add) {
+ ret = cgroup_add_file(css, cgrp, cft);
+ if (ret) {
+ pr_warn("%s: failed to add %s, err=%d\n",
+ __func__, cft->name, ret);
+ cft_end = cft;
+ is_add = false;
+ goto restart;
+ }
+ } else {
+ cgroup_rm_file(cgrp, cft);
+ }
+ }
+ return ret;
+}
+
+static int cgroup_apply_cftypes(struct cftype *cfts, bool is_add)
+{
+ LIST_HEAD(pending);
+ struct cgroup_subsys *ss = cfts[0].ss;
+ struct cgroup *root = &ss->root->cgrp;
+ struct cgroup_subsys_state *css;
+ int ret = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /* add/rm files for all cgroups created before */
+ css_for_each_descendant_pre(css, cgroup_css(root, ss)) {
+ struct cgroup *cgrp = css->cgroup;
+
+ if (!(css->flags & CSS_VISIBLE))
+ continue;
+
+ ret = cgroup_addrm_files(css, cgrp, cfts, is_add);
+ if (ret)
+ break;
+ }
+
+ if (is_add && !ret)
+ kernfs_activate(root->kn);
+ return ret;
+}
+
+static void cgroup_exit_cftypes(struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ /* free copy for custom atomic_write_len, see init_cftypes() */
+ if (cft->max_write_len && cft->max_write_len != PAGE_SIZE)
+ kfree(cft->kf_ops);
+ cft->kf_ops = NULL;
+ cft->ss = NULL;
+
+ /* revert flags set by cgroup core while adding @cfts */
+ cft->flags &= ~(__CFTYPE_ONLY_ON_DFL | __CFTYPE_NOT_ON_DFL);
+ }
+}
+
+static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft->name[0] != '\0'; cft++) {
+ struct kernfs_ops *kf_ops;
+
+ WARN_ON(cft->ss || cft->kf_ops);
+
+ if (cft->seq_start)
+ kf_ops = &cgroup_kf_ops;
+ else
+ kf_ops = &cgroup_kf_single_ops;
+
+ /*
+ * Ugh... if @cft wants a custom max_write_len, we need to
+ * make a copy of kf_ops to set its atomic_write_len.
+ */
+ if (cft->max_write_len && cft->max_write_len != PAGE_SIZE) {
+ kf_ops = kmemdup(kf_ops, sizeof(*kf_ops), GFP_KERNEL);
+ if (!kf_ops) {
+ cgroup_exit_cftypes(cfts);
+ return -ENOMEM;
+ }
+ kf_ops->atomic_write_len = cft->max_write_len;
+ }
+
+ cft->kf_ops = kf_ops;
+ cft->ss = ss;
+ }
+
+ return 0;
+}
+
+static int cgroup_rm_cftypes_locked(struct cftype *cfts)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (!cfts || !cfts[0].ss)
+ return -ENOENT;
+
+ list_del(&cfts->node);
+ cgroup_apply_cftypes(cfts, false);
+ cgroup_exit_cftypes(cfts);
+ return 0;
+}
+
+/**
+ * cgroup_rm_cftypes - remove an array of cftypes from a subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Unregister @cfts. Files described by @cfts are removed from all
+ * existing cgroups and all future cgroups won't have them either. This
+ * function can be called anytime whether @cfts' subsys is attached or not.
+ *
+ * Returns 0 on successful unregistration, -ENOENT if @cfts is not
+ * registered.
+ */
+int cgroup_rm_cftypes(struct cftype *cfts)
+{
+ int ret;
+
+ mutex_lock(&cgroup_mutex);
+ ret = cgroup_rm_cftypes_locked(cfts);
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
+/**
+ * cgroup_add_cftypes - add an array of cftypes to a subsystem
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Register @cfts to @ss. Files described by @cfts are created for all
+ * existing cgroups to which @ss is attached and all future cgroups will
+ * have them too. This function can be called anytime whether @ss is
+ * attached or not.
+ *
+ * Returns 0 on successful registration, -errno on failure. Note that this
+ * function currently returns 0 as long as @cfts registration is successful
+ * even if some file creation attempts on existing cgroups fail.
+ */
+static int cgroup_add_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ int ret;
+
+ if (!cgroup_ssid_enabled(ss->id))
+ return 0;
+
+ if (!cfts || cfts[0].name[0] == '\0')
+ return 0;
+
+ ret = cgroup_init_cftypes(ss, cfts);
+ if (ret)
+ return ret;
+
+ mutex_lock(&cgroup_mutex);
+
+ list_add_tail(&cfts->node, &ss->cfts);
+ ret = cgroup_apply_cftypes(cfts, true);
+ if (ret)
+ cgroup_rm_cftypes_locked(cfts);
+
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
+/**
+ * cgroup_add_dfl_cftypes - add an array of cftypes for default hierarchy
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the default hierarchy.
+ */
+int cgroup_add_dfl_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+ cft->flags |= __CFTYPE_ONLY_ON_DFL;
+ return cgroup_add_cftypes(ss, cfts);
+}
+
+/**
+ * cgroup_add_legacy_cftypes - add an array of cftypes for legacy hierarchies
+ * @ss: target cgroup subsystem
+ * @cfts: zero-length name terminated array of cftypes
+ *
+ * Similar to cgroup_add_cftypes() but the added files are only used for
+ * the legacy hierarchies.
+ */
+int cgroup_add_legacy_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
+{
+ struct cftype *cft;
+
+ for (cft = cfts; cft && cft->name[0] != '\0'; cft++)
+ cft->flags |= __CFTYPE_NOT_ON_DFL;
+ return cgroup_add_cftypes(ss, cfts);
+}
+
+/**
+ * cgroup_file_notify - generate a file modified event for a cgroup_file
+ * @cfile: target cgroup_file
+ *
+ * @cfile must have been obtained by setting cftype->file_offset.
+ */
+void cgroup_file_notify(struct cgroup_file *cfile)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&cgroup_file_kn_lock, flags);
+ if (cfile->kn)
+ kernfs_notify(cfile->kn);
+ spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
+}
+
+/**
+ * cgroup_task_count - count the number of tasks in a cgroup.
+ * @cgrp: the cgroup in question
+ *
+ * Return the number of tasks in the cgroup. The returned number can be
+ * higher than the actual number of tasks due to css_set references from
+ * namespace roots and temporary usages.
+ */
+static int cgroup_task_count(const struct cgroup *cgrp)
+{
+ int count = 0;
+ struct cgrp_cset_link *link;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &cgrp->cset_links, cset_link)
+ count += atomic_read(&link->cset->refcount);
+ spin_unlock_irq(&css_set_lock);
+ return count;
+}
+
+/**
+ * css_next_child - find the next child of a given css
+ * @pos: the current position (%NULL to initiate traversal)
+ * @parent: css whose children to walk
+ *
+ * This function returns the next child of @parent and should be called
+ * under either cgroup_mutex or RCU read lock. The only requirement is
+ * that @parent and @pos are accessible. The next sibling is guaranteed to
+ * be returned regardless of their states.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ */
+struct cgroup_subsys_state *css_next_child(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *parent)
+{
+ struct cgroup_subsys_state *next;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ /*
+ * @pos could already have been unlinked from the sibling list.
+ * Once a cgroup is removed, its ->sibling.next is no longer
+ * updated when its next sibling changes. CSS_RELEASED is set when
+ * @pos is taken off list, at which time its next pointer is valid,
+ * and, as releases are serialized, the one pointed to by the next
+ * pointer is guaranteed to not have started release yet. This
+ * implies that if we observe !CSS_RELEASED on @pos in this RCU
+ * critical section, the one pointed to by its next pointer is
+ * guaranteed to not have finished its RCU grace period even if we
+ * have dropped rcu_read_lock() inbetween iterations.
+ *
+ * If @pos has CSS_RELEASED set, its next pointer can't be
+ * dereferenced; however, as each css is given a monotonically
+ * increasing unique serial number and always appended to the
+ * sibling list, the next one can be found by walking the parent's
+ * children until the first css with higher serial number than
+ * @pos's. While this path can be slower, it happens iff iteration
+ * races against release and the race window is very small.
+ */
+ if (!pos) {
+ next = list_entry_rcu(parent->children.next, struct cgroup_subsys_state, sibling);
+ } else if (likely(!(pos->flags & CSS_RELEASED))) {
+ next = list_entry_rcu(pos->sibling.next, struct cgroup_subsys_state, sibling);
+ } else {
+ list_for_each_entry_rcu(next, &parent->children, sibling)
+ if (next->serial_nr > pos->serial_nr)
+ break;
+ }
+
+ /*
+ * @next, if not pointing to the head, can be dereferenced and is
+ * the next sibling.
+ */
+ if (&next->sibling != &parent->children)
+ return next;
+ return NULL;
+}
+
+/**
+ * css_next_descendant_pre - find the next descendant for pre-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: css whose descendants to walk
+ *
+ * To be used by css_for_each_descendant_pre(). Find the next descendant
+ * to visit for pre-order traversal of @root's descendants. @root is
+ * included in the iteration and the first node to be visited.
+ *
+ * While this function requires cgroup_mutex or RCU read locking, it
+ * doesn't require the whole traversal to be contained in a single critical
+ * section. This function will return the correct next descendant as long
+ * as both @pos and @root are accessible and @pos is a descendant of @root.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ */
+struct cgroup_subsys_state *
+css_next_descendant_pre(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *root)
+{
+ struct cgroup_subsys_state *next;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ /* if first iteration, visit @root */
+ if (!pos)
+ return root;
+
+ /* visit the first child if exists */
+ next = css_next_child(NULL, pos);
+ if (next)
+ return next;
+
+ /* no child, visit my or the closest ancestor's next sibling */
+ while (pos != root) {
+ next = css_next_child(pos, pos->parent);
+ if (next)
+ return next;
+ pos = pos->parent;
+ }
+
+ return NULL;
+}
+
+/**
+ * css_rightmost_descendant - return the rightmost descendant of a css
+ * @pos: css of interest
+ *
+ * Return the rightmost descendant of @pos. If there's no descendant, @pos
+ * is returned. This can be used during pre-order traversal to skip
+ * subtree of @pos.
+ *
+ * While this function requires cgroup_mutex or RCU read locking, it
+ * doesn't require the whole traversal to be contained in a single critical
+ * section. This function will return the correct rightmost descendant as
+ * long as @pos is accessible.
+ */
+struct cgroup_subsys_state *
+css_rightmost_descendant(struct cgroup_subsys_state *pos)
+{
+ struct cgroup_subsys_state *last, *tmp;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ do {
+ last = pos;
+ /* ->prev isn't RCU safe, walk ->next till the end */
+ pos = NULL;
+ css_for_each_child(tmp, last)
+ pos = tmp;
+ } while (pos);
+
+ return last;
+}
+
+static struct cgroup_subsys_state *
+css_leftmost_descendant(struct cgroup_subsys_state *pos)
+{
+ struct cgroup_subsys_state *last;
+
+ do {
+ last = pos;
+ pos = css_next_child(NULL, pos);
+ } while (pos);
+
+ return last;
+}
+
+/**
+ * css_next_descendant_post - find the next descendant for post-order walk
+ * @pos: the current position (%NULL to initiate traversal)
+ * @root: css whose descendants to walk
+ *
+ * To be used by css_for_each_descendant_post(). Find the next descendant
+ * to visit for post-order traversal of @root's descendants. @root is
+ * included in the iteration and the last node to be visited.
+ *
+ * While this function requires cgroup_mutex or RCU read locking, it
+ * doesn't require the whole traversal to be contained in a single critical
+ * section. This function will return the correct next descendant as long
+ * as both @pos and @cgroup are accessible and @pos is a descendant of
+ * @cgroup.
+ *
+ * If a subsystem synchronizes ->css_online() and the start of iteration, a
+ * css which finished ->css_online() is guaranteed to be visible in the
+ * future iterations and will stay visible until the last reference is put.
+ * A css which hasn't finished ->css_online() or already finished
+ * ->css_offline() may show up during traversal. It's each subsystem's
+ * responsibility to synchronize against on/offlining.
+ */
+struct cgroup_subsys_state *
+css_next_descendant_post(struct cgroup_subsys_state *pos,
+ struct cgroup_subsys_state *root)
+{
+ struct cgroup_subsys_state *next;
+
+ cgroup_assert_mutex_or_rcu_locked();
+
+ /* if first iteration, visit leftmost descendant which may be @root */
+ if (!pos)
+ return css_leftmost_descendant(root);
+
+ /* if we visited @root, we're done */
+ if (pos == root)
+ return NULL;
+
+ /* if there's an unvisited sibling, visit its leftmost descendant */
+ next = css_next_child(pos, pos->parent);
+ if (next)
+ return css_leftmost_descendant(next);
+
+ /* no sibling left, visit parent */
+ return pos->parent;
+}
+
+/**
+ * css_has_online_children - does a css have online children
+ * @css: the target css
+ *
+ * Returns %true if @css has any online children; otherwise, %false. This
+ * function can be called from any context but the caller is responsible
+ * for synchronizing against on/offlining as necessary.
+ */
+bool css_has_online_children(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys_state *child;
+ bool ret = false;
+
+ rcu_read_lock();
+ css_for_each_child(child, css) {
+ if (child->flags & CSS_ONLINE) {
+ ret = true;
+ break;
+ }
+ }
+ rcu_read_unlock();
+ return ret;
+}
+
+/**
+ * css_task_iter_advance_css_set - advance a task itererator to the next css_set
+ * @it: the iterator to advance
+ *
+ * Advance @it to the next css_set to walk.
+ */
+static void css_task_iter_advance_css_set(struct css_task_iter *it)
+{
+ struct list_head *l = it->cset_pos;
+ struct cgrp_cset_link *link;
+ struct css_set *cset;
+
+ lockdep_assert_held(&css_set_lock);
+
+ /* Advance to the next non-empty css_set */
+ do {
+ l = l->next;
+ if (l == it->cset_head) {
+ it->cset_pos = NULL;
+ it->task_pos = NULL;
+ return;
+ }
+
+ if (it->ss) {
+ cset = container_of(l, struct css_set,
+ e_cset_node[it->ss->id]);
+ } else {
+ link = list_entry(l, struct cgrp_cset_link, cset_link);
+ cset = link->cset;
+ }
+ } while (!css_set_populated(cset));
+
+ it->cset_pos = l;
+
+ if (!list_empty(&cset->tasks))
+ it->task_pos = cset->tasks.next;
+ else
+ it->task_pos = cset->mg_tasks.next;
+
+ it->tasks_head = &cset->tasks;
+ it->mg_tasks_head = &cset->mg_tasks;
+
+ /*
+ * We don't keep css_sets locked across iteration steps and thus
+ * need to take steps to ensure that iteration can be resumed after
+ * the lock is re-acquired. Iteration is performed at two levels -
+ * css_sets and tasks in them.
+ *
+ * Once created, a css_set never leaves its cgroup lists, so a
+ * pinned css_set is guaranteed to stay put and we can resume
+ * iteration afterwards.
+ *
+ * Tasks may leave @cset across iteration steps. This is resolved
+ * by registering each iterator with the css_set currently being
+ * walked and making css_set_move_task() advance iterators whose
+ * next task is leaving.
+ */
+ if (it->cur_cset) {
+ list_del(&it->iters_node);
+ put_css_set_locked(it->cur_cset);
+ }
+ get_css_set(cset);
+ it->cur_cset = cset;
+ list_add(&it->iters_node, &cset->task_iters);
+}
+
+static void css_task_iter_advance(struct css_task_iter *it)
+{
+ struct list_head *l = it->task_pos;
+
+ lockdep_assert_held(&css_set_lock);
+ WARN_ON_ONCE(!l);
+
+ /*
+ * Advance iterator to find next entry. cset->tasks is consumed
+ * first and then ->mg_tasks. After ->mg_tasks, we move onto the
+ * next cset.
+ */
+ l = l->next;
+
+ if (l == it->tasks_head)
+ l = it->mg_tasks_head->next;
+
+ if (l == it->mg_tasks_head)
+ css_task_iter_advance_css_set(it);
+ else
+ it->task_pos = l;
+}
+
+/**
+ * css_task_iter_start - initiate task iteration
+ * @css: the css to walk tasks of
+ * @it: the task iterator to use
+ *
+ * Initiate iteration through the tasks of @css. The caller can call
+ * css_task_iter_next() to walk through the tasks until the function
+ * returns NULL. On completion of iteration, css_task_iter_end() must be
+ * called.
+ */
+void css_task_iter_start(struct cgroup_subsys_state *css,
+ struct css_task_iter *it)
+{
+ /* no one should try to iterate before mounting cgroups */
+ WARN_ON_ONCE(!use_task_css_set_links);
+
+ memset(it, 0, sizeof(*it));
+
+ spin_lock_irq(&css_set_lock);
+
+ it->ss = css->ss;
+
+ if (it->ss)
+ it->cset_pos = &css->cgroup->e_csets[css->ss->id];
+ else
+ it->cset_pos = &css->cgroup->cset_links;
+
+ it->cset_head = it->cset_pos;
+
+ css_task_iter_advance_css_set(it);
+
+ spin_unlock_irq(&css_set_lock);
+}
+
+/**
+ * css_task_iter_next - return the next task for the iterator
+ * @it: the task iterator being iterated
+ *
+ * The "next" function for task iteration. @it should have been
+ * initialized via css_task_iter_start(). Returns NULL when the iteration
+ * reaches the end.
+ */
+struct task_struct *css_task_iter_next(struct css_task_iter *it)
+{
+ if (it->cur_task) {
+ put_task_struct(it->cur_task);
+ it->cur_task = NULL;
+ }
+
+ spin_lock_irq(&css_set_lock);
+
+ if (it->task_pos) {
+ it->cur_task = list_entry(it->task_pos, struct task_struct,
+ cg_list);
+ get_task_struct(it->cur_task);
+ css_task_iter_advance(it);
+ }
+
+ spin_unlock_irq(&css_set_lock);
+
+ return it->cur_task;
+}
+
+/**
+ * css_task_iter_end - finish task iteration
+ * @it: the task iterator to finish
+ *
+ * Finish task iteration started by css_task_iter_start().
+ */
+void css_task_iter_end(struct css_task_iter *it)
+{
+ if (it->cur_cset) {
+ spin_lock_irq(&css_set_lock);
+ list_del(&it->iters_node);
+ put_css_set_locked(it->cur_cset);
+ spin_unlock_irq(&css_set_lock);
+ }
+
+ if (it->cur_task)
+ put_task_struct(it->cur_task);
+}
+
+/**
+ * cgroup_trasnsfer_tasks - move tasks from one cgroup to another
+ * @to: cgroup to which the tasks will be moved
+ * @from: cgroup in which the tasks currently reside
+ *
+ * Locking rules between cgroup_post_fork() and the migration path
+ * guarantee that, if a task is forking while being migrated, the new child
+ * is guaranteed to be either visible in the source cgroup after the
+ * parent's migration is complete or put into the target cgroup. No task
+ * can slip out of migration through forking.
+ */
+int cgroup_transfer_tasks(struct cgroup *to, struct cgroup *from)
+{
+ LIST_HEAD(preloaded_csets);
+ struct cgrp_cset_link *link;
+ struct css_task_iter it;
+ struct task_struct *task;
+ int ret;
+
+ if (cgroup_on_dfl(to))
+ return -EINVAL;
+
+ if (!cgroup_may_migrate_to(to))
+ return -EBUSY;
+
+ mutex_lock(&cgroup_mutex);
+
+ percpu_down_write(&cgroup_threadgroup_rwsem);
+
+ /* all tasks in @from are being moved, all csets are source */
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &from->cset_links, cset_link)
+ cgroup_migrate_add_src(link->cset, to, &preloaded_csets);
+ spin_unlock_irq(&css_set_lock);
+
+ ret = cgroup_migrate_prepare_dst(&preloaded_csets);
+ if (ret)
+ goto out_err;
+
+ /*
+ * Migrate tasks one-by-one until @from is empty. This fails iff
+ * ->can_attach() fails.
+ */
+ do {
+ css_task_iter_start(&from->self, &it);
+ task = css_task_iter_next(&it);
+ if (task)
+ get_task_struct(task);
+ css_task_iter_end(&it);
+
+ if (task) {
+ ret = cgroup_migrate(task, false, to->root);
+ if (!ret)
+ trace_cgroup_transfer_tasks(to, task, false);
+ put_task_struct(task);
+ }
+ } while (task && !ret);
+out_err:
+ cgroup_migrate_finish(&preloaded_csets);
+ percpu_up_write(&cgroup_threadgroup_rwsem);
+ mutex_unlock(&cgroup_mutex);
+ return ret;
+}
+
+static void cgroup_procs_release(struct kernfs_open_file *of)
+{
+ if (of->priv) {
+ css_task_iter_end(of->priv);
+ kfree(of->priv);
+ }
+}
+
+static void *cgroup_procs_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct kernfs_open_file *of = s->private;
+ struct css_task_iter *it = of->priv;
+ struct task_struct *task;
+
+ do {
+ task = css_task_iter_next(it);
+ } while (task && !thread_group_leader(task));
+
+ return task;
+}
+
+static void *cgroup_procs_start(struct seq_file *s, loff_t *pos)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+ struct css_task_iter *it = of->priv;
+
+ /*
+ * When a seq_file is seeked, it's always traversed sequentially
+ * from position 0, so we can simply keep iterating on !0 *pos.
+ */
+ if (!it) {
+ if (WARN_ON_ONCE((*pos)++))
+ return ERR_PTR(-EINVAL);
+
+ it = kzalloc(sizeof(*it), GFP_KERNEL);
+ if (!it)
+ return ERR_PTR(-ENOMEM);
+ of->priv = it;
+ css_task_iter_start(&cgrp->self, it);
+ } else if (!(*pos)++) {
+ css_task_iter_end(it);
+ css_task_iter_start(&cgrp->self, it);
+ }
+
+ return cgroup_procs_next(s, NULL, NULL);
+}
+
+static int cgroup_procs_show(struct seq_file *s, void *v)
+{
+ seq_printf(s, "%d\n", task_tgid_vnr(v));
+ return 0;
+}
+
+/*
+ * Stuff for reading the 'tasks'/'procs' files.
+ *
+ * Reading this file can return large amounts of data if a cgroup has
+ * *lots* of attached tasks. So it may need several calls to read(),
+ * but we cannot guarantee that the information we produce is correct
+ * unless we produce it entirely atomically.
+ *
+ */
+
+/* which pidlist file are we talking about? */
+enum cgroup_filetype {
+ CGROUP_FILE_PROCS,
+ CGROUP_FILE_TASKS,
+};
+
+/*
+ * A pidlist is a list of pids that virtually represents the contents of one
+ * of the cgroup files ("procs" or "tasks"). We keep a list of such pidlists,
+ * a pair (one each for procs, tasks) for each pid namespace that's relevant
+ * to the cgroup.
+ */
+struct cgroup_pidlist {
+ /*
+ * used to find which pidlist is wanted. doesn't change as long as
+ * this particular list stays in the list.
+ */
+ struct { enum cgroup_filetype type; struct pid_namespace *ns; } key;
+ /* array of xids */
+ pid_t *list;
+ /* how many elements the above list has */
+ int length;
+ /* each of these stored in a list by its cgroup */
+ struct list_head links;
+ /* pointer to the cgroup we belong to, for list removal purposes */
+ struct cgroup *owner;
+ /* for delayed destruction */
+ struct delayed_work destroy_dwork;
+};
+
+/*
+ * The following two functions "fix" the issue where there are more pids
+ * than kmalloc will give memory for; in such cases, we use vmalloc/vfree.
+ * TODO: replace with a kernel-wide solution to this problem
+ */
+#define PIDLIST_TOO_LARGE(c) ((c) * sizeof(pid_t) > (PAGE_SIZE * 2))
+static void *pidlist_allocate(int count)
+{
+ if (PIDLIST_TOO_LARGE(count))
+ return vmalloc(count * sizeof(pid_t));
+ else
+ return kmalloc(count * sizeof(pid_t), GFP_KERNEL);
+}
+
+static void pidlist_free(void *p)
+{
+ kvfree(p);
+}
+
+/*
+ * Used to destroy all pidlists lingering waiting for destroy timer. None
+ * should be left afterwards.
+ */
+static void cgroup_pidlist_destroy_all(struct cgroup *cgrp)
+{
+ struct cgroup_pidlist *l, *tmp_l;
+
+ mutex_lock(&cgrp->pidlist_mutex);
+ list_for_each_entry_safe(l, tmp_l, &cgrp->pidlists, links)
+ mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork, 0);
+ mutex_unlock(&cgrp->pidlist_mutex);
+
+ flush_workqueue(cgroup_pidlist_destroy_wq);
+ BUG_ON(!list_empty(&cgrp->pidlists));
+}
+
+static void cgroup_pidlist_destroy_work_fn(struct work_struct *work)
+{
+ struct delayed_work *dwork = to_delayed_work(work);
+ struct cgroup_pidlist *l = container_of(dwork, struct cgroup_pidlist,
+ destroy_dwork);
+ struct cgroup_pidlist *tofree = NULL;
+
+ mutex_lock(&l->owner->pidlist_mutex);
+
+ /*
+ * Destroy iff we didn't get queued again. The state won't change
+ * as destroy_dwork can only be queued while locked.
+ */
+ if (!delayed_work_pending(dwork)) {
+ list_del(&l->links);
+ pidlist_free(l->list);
+ put_pid_ns(l->key.ns);
+ tofree = l;
+ }
+
+ mutex_unlock(&l->owner->pidlist_mutex);
+ kfree(tofree);
+}
+
+/*
+ * pidlist_uniq - given a kmalloc()ed list, strip out all duplicate entries
+ * Returns the number of unique elements.
+ */
+static int pidlist_uniq(pid_t *list, int length)
+{
+ int src, dest = 1;
+
+ /*
+ * we presume the 0th element is unique, so i starts at 1. trivial
+ * edge cases first; no work needs to be done for either
+ */
+ if (length == 0 || length == 1)
+ return length;
+ /* src and dest walk down the list; dest counts unique elements */
+ for (src = 1; src < length; src++) {
+ /* find next unique element */
+ while (list[src] == list[src-1]) {
+ src++;
+ if (src == length)
+ goto after;
+ }
+ /* dest always points to where the next unique element goes */
+ list[dest] = list[src];
+ dest++;
+ }
+after:
+ return dest;
+}
+
+/*
+ * The two pid files - task and cgroup.procs - guaranteed that the result
+ * is sorted, which forced this whole pidlist fiasco. As pid order is
+ * different per namespace, each namespace needs differently sorted list,
+ * making it impossible to use, for example, single rbtree of member tasks
+ * sorted by task pointer. As pidlists can be fairly large, allocating one
+ * per open file is dangerous, so cgroup had to implement shared pool of
+ * pidlists keyed by cgroup and namespace.
+ */
+static int cmppid(const void *a, const void *b)
+{
+ return *(pid_t *)a - *(pid_t *)b;
+}
+
+static struct cgroup_pidlist *cgroup_pidlist_find(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ struct pid_namespace *ns = task_active_pid_ns(current);
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ list_for_each_entry(l, &cgrp->pidlists, links)
+ if (l->key.type == type && l->key.ns == ns)
+ return l;
+ return NULL;
+}
+
+/*
+ * find the appropriate pidlist for our purpose (given procs vs tasks)
+ * returns with the lock on that pidlist already held, and takes care
+ * of the use count, or returns NULL with no locks held if we're out of
+ * memory.
+ */
+static struct cgroup_pidlist *cgroup_pidlist_find_create(struct cgroup *cgrp,
+ enum cgroup_filetype type)
+{
+ struct cgroup_pidlist *l;
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ l = cgroup_pidlist_find(cgrp, type);
+ if (l)
+ return l;
+
+ /* entry not found; create a new one */
+ l = kzalloc(sizeof(struct cgroup_pidlist), GFP_KERNEL);
+ if (!l)
+ return l;
+
+ INIT_DELAYED_WORK(&l->destroy_dwork, cgroup_pidlist_destroy_work_fn);
+ l->key.type = type;
+ /* don't need task_nsproxy() if we're looking at ourself */
+ l->key.ns = get_pid_ns(task_active_pid_ns(current));
+ l->owner = cgrp;
+ list_add(&l->links, &cgrp->pidlists);
+ return l;
+}
+
+/*
+ * Load a cgroup's pidarray with either procs' tgids or tasks' pids
+ */
+static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
+ struct cgroup_pidlist **lp)
+{
+ pid_t *array;
+ int length;
+ int pid, n = 0; /* used for populating the array */
+ struct css_task_iter it;
+ struct task_struct *tsk;
+ struct cgroup_pidlist *l;
+
+ lockdep_assert_held(&cgrp->pidlist_mutex);
+
+ /*
+ * If cgroup gets more users after we read count, we won't have
+ * enough space - tough. This race is indistinguishable to the
+ * caller from the case that the additional cgroup users didn't
+ * show up until sometime later on.
+ */
+ length = cgroup_task_count(cgrp);
+ array = pidlist_allocate(length);
+ if (!array)
+ return -ENOMEM;
+ /* now, populate the array */
+ css_task_iter_start(&cgrp->self, &it);
+ while ((tsk = css_task_iter_next(&it))) {
+ if (unlikely(n == length))
+ break;
+ /* get tgid or pid for procs or tasks file respectively */
+ if (type == CGROUP_FILE_PROCS)
+ pid = task_tgid_vnr(tsk);
+ else
+ pid = task_pid_vnr(tsk);
+ if (pid > 0) /* make sure to only use valid results */
+ array[n++] = pid;
+ }
+ css_task_iter_end(&it);
+ length = n;
+ /* now sort & (if procs) strip out duplicates */
+ sort(array, length, sizeof(pid_t), cmppid, NULL);
+ if (type == CGROUP_FILE_PROCS)
+ length = pidlist_uniq(array, length);
+
+ l = cgroup_pidlist_find_create(cgrp, type);
+ if (!l) {
+ pidlist_free(array);
+ return -ENOMEM;
+ }
+
+ /* store array, freeing old if necessary */
+ pidlist_free(l->list);
+ l->list = array;
+ l->length = length;
+ *lp = l;
+ return 0;
+}
+
+/**
+ * cgroupstats_build - build and fill cgroupstats
+ * @stats: cgroupstats to fill information into
+ * @dentry: A dentry entry belonging to the cgroup for which stats have
+ * been requested.
+ *
+ * Build and fill cgroupstats so that taskstats can export it to user
+ * space.
+ */
+int cgroupstats_build(struct cgroupstats *stats, struct dentry *dentry)
+{
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+ struct cgroup *cgrp;
+ struct css_task_iter it;
+ struct task_struct *tsk;
+
+ /* it should be kernfs_node belonging to cgroupfs and is a directory */
+ if (dentry->d_sb->s_type != &cgroup_fs_type || !kn ||
+ kernfs_type(kn) != KERNFS_DIR)
+ return -EINVAL;
+
+ mutex_lock(&cgroup_mutex);
+
+ /*
+ * We aren't being called from kernfs and there's no guarantee on
+ * @kn->priv's validity. For this and css_tryget_online_from_dir(),
+ * @kn->priv is RCU safe. Let's do the RCU dancing.
+ */
+ rcu_read_lock();
+ cgrp = rcu_dereference(kn->priv);
+ if (!cgrp || cgroup_is_dead(cgrp)) {
+ rcu_read_unlock();
+ mutex_unlock(&cgroup_mutex);
+ return -ENOENT;
+ }
+ rcu_read_unlock();
+
+ css_task_iter_start(&cgrp->self, &it);
+ while ((tsk = css_task_iter_next(&it))) {
+ switch (tsk->state) {
+ case TASK_RUNNING:
+ stats->nr_running++;
+ break;
+ case TASK_INTERRUPTIBLE:
+ stats->nr_sleeping++;
+ break;
+ case TASK_UNINTERRUPTIBLE:
+ stats->nr_uninterruptible++;
+ break;
+ case TASK_STOPPED:
+ stats->nr_stopped++;
+ break;
+ default:
+ if (delayacct_is_task_waiting_on_io(tsk))
+ stats->nr_io_wait++;
+ break;
+ }
+ }
+ css_task_iter_end(&it);
+
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+}
+
+
+/*
+ * seq_file methods for the tasks/procs files. The seq_file position is the
+ * next pid to display; the seq_file iterator is a pointer to the pid
+ * in the cgroup->l->list array.
+ */
+
+static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
+{
+ /*
+ * Initially we receive a position value that corresponds to
+ * one more than the last pid shown (or 0 on the first call or
+ * after a seek to the start). Use a binary-search to find the
+ * next pid to display, if any
+ */
+ struct kernfs_open_file *of = s->private;
+ struct cgroup *cgrp = seq_css(s)->cgroup;
+ struct cgroup_pidlist *l;
+ enum cgroup_filetype type = seq_cft(s)->private;
+ int index = 0, pid = *pos;
+ int *iter, ret;
+
+ mutex_lock(&cgrp->pidlist_mutex);
+
+ /*
+ * !NULL @of->priv indicates that this isn't the first start()
+ * after open. If the matching pidlist is around, we can use that.
+ * Look for it. Note that @of->priv can't be used directly. It
+ * could already have been destroyed.
+ */
+ if (of->priv)
+ of->priv = cgroup_pidlist_find(cgrp, type);
+
+ /*
+ * Either this is the first start() after open or the matching
+ * pidlist has been destroyed inbetween. Create a new one.
+ */
+ if (!of->priv) {
+ ret = pidlist_array_load(cgrp, type,
+ (struct cgroup_pidlist **)&of->priv);
+ if (ret)
+ return ERR_PTR(ret);
+ }
+ l = of->priv;
+
+ if (pid) {
+ int end = l->length;
+
+ while (index < end) {
+ int mid = (index + end) / 2;
+ if (l->list[mid] == pid) {
+ index = mid;
+ break;
+ } else if (l->list[mid] <= pid)
+ index = mid + 1;
+ else
+ end = mid;
+ }
+ }
+ /* If we're off the end of the array, we're done */
+ if (index >= l->length)
+ return NULL;
+ /* Update the abstract position to be the actual pid that we found */
+ iter = l->list + index;
+ *pos = *iter;
+ return iter;
+}
+
+static void cgroup_pidlist_stop(struct seq_file *s, void *v)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_pidlist *l = of->priv;
+
+ if (l)
+ mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
+ CGROUP_PIDLIST_DESTROY_DELAY);
+ mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
+}
+
+static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)
+{
+ struct kernfs_open_file *of = s->private;
+ struct cgroup_pidlist *l = of->priv;
+ pid_t *p = v;
+ pid_t *end = l->list + l->length;
+ /*
+ * Advance to the next pid in the array. If this goes off the
+ * end, we're done
+ */
+ p++;
+ if (p >= end) {
+ return NULL;
+ } else {
+ *pos = *p;
+ return p;
+ }
+}
+
+static int cgroup_pidlist_show(struct seq_file *s, void *v)
+{
+ seq_printf(s, "%d\n", *(int *)v);
+
+ return 0;
+}
+
+static u64 cgroup_read_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return notify_on_release(css->cgroup);
+}
+
+static int cgroup_write_notify_on_release(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val)
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+ else
+ clear_bit(CGRP_NOTIFY_ON_RELEASE, &css->cgroup->flags);
+ return 0;
+}
+
+static u64 cgroup_clone_children_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+}
+
+static int cgroup_clone_children_write(struct cgroup_subsys_state *css,
+ struct cftype *cft, u64 val)
+{
+ if (val)
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+ else
+ clear_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags);
+ return 0;
+}
+
+/* cgroup core interface files for the default hierarchy */
+static struct cftype cgroup_dfl_base_files[] = {
+ {
+ .name = "cgroup.procs",
+ .file_offset = offsetof(struct cgroup, procs_file),
+ .release = cgroup_procs_release,
+ .seq_start = cgroup_procs_start,
+ .seq_next = cgroup_procs_next,
+ .seq_show = cgroup_procs_show,
+ .write = cgroup_procs_write,
+ },
+ {
+ .name = "cgroup.controllers",
+ .seq_show = cgroup_controllers_show,
+ },
+ {
+ .name = "cgroup.subtree_control",
+ .seq_show = cgroup_subtree_control_show,
+ .write = cgroup_subtree_control_write,
+ },
+ {
+ .name = "cgroup.events",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .file_offset = offsetof(struct cgroup, events_file),
+ .seq_show = cgroup_events_show,
+ },
+ { } /* terminate */
+};
+
+/* cgroup core interface files for the legacy hierarchies */
+static struct cftype cgroup_legacy_base_files[] = {
+ {
+ .name = "cgroup.procs",
+ .seq_start = cgroup_pidlist_start,
+ .seq_next = cgroup_pidlist_next,
+ .seq_stop = cgroup_pidlist_stop,
+ .seq_show = cgroup_pidlist_show,
+ .private = CGROUP_FILE_PROCS,
+ .write = cgroup_procs_write,
+ },
+ {
+ .name = "cgroup.clone_children",
+ .read_u64 = cgroup_clone_children_read,
+ .write_u64 = cgroup_clone_children_write,
+ },
+ {
+ .name = "cgroup.sane_behavior",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .seq_show = cgroup_sane_behavior_show,
+ },
+ {
+ .name = "tasks",
+ .seq_start = cgroup_pidlist_start,
+ .seq_next = cgroup_pidlist_next,
+ .seq_stop = cgroup_pidlist_stop,
+ .seq_show = cgroup_pidlist_show,
+ .private = CGROUP_FILE_TASKS,
+ .write = cgroup_tasks_write,
+ },
+ {
+ .name = "notify_on_release",
+ .read_u64 = cgroup_read_notify_on_release,
+ .write_u64 = cgroup_write_notify_on_release,
+ },
+ {
+ .name = "release_agent",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .seq_show = cgroup_release_agent_show,
+ .write = cgroup_release_agent_write,
+ .max_write_len = PATH_MAX - 1,
+ },
+ { } /* terminate */
+};
+
+/*
+ * css destruction is four-stage process.
+ *
+ * 1. Destruction starts. Killing of the percpu_ref is initiated.
+ * Implemented in kill_css().
+ *
+ * 2. When the percpu_ref is confirmed to be visible as killed on all CPUs
+ * and thus css_tryget_online() is guaranteed to fail, the css can be
+ * offlined by invoking offline_css(). After offlining, the base ref is
+ * put. Implemented in css_killed_work_fn().
+ *
+ * 3. When the percpu_ref reaches zero, the only possible remaining
+ * accessors are inside RCU read sections. css_release() schedules the
+ * RCU callback.
+ *
+ * 4. After the grace period, the css can be freed. Implemented in
+ * css_free_work_fn().
+ *
+ * It is actually hairier because both step 2 and 4 require process context
+ * and thus involve punting to css->destroy_work adding two additional
+ * steps to the already complex sequence.
+ */
+static void css_free_work_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup_subsys *ss = css->ss;
+ struct cgroup *cgrp = css->cgroup;
+
+ percpu_ref_exit(&css->refcnt);
+
+ if (ss) {
+ /* css free path */
+ struct cgroup_subsys_state *parent = css->parent;
+ int id = css->id;
+
+ ss->css_free(css);
+ cgroup_idr_remove(&ss->css_idr, id);
+ cgroup_put(cgrp);
+
+ if (parent)
+ css_put(parent);
+ } else {
+ /* cgroup free path */
+ atomic_dec(&cgrp->root->nr_cgrps);
+ cgroup_pidlist_destroy_all(cgrp);
+ cancel_work_sync(&cgrp->release_agent_work);
+
+ if (cgroup_parent(cgrp)) {
+ /*
+ * We get a ref to the parent, and put the ref when
+ * this cgroup is being freed, so it's guaranteed
+ * that the parent won't be destroyed before its
+ * children.
+ */
+ cgroup_put(cgroup_parent(cgrp));
+ kernfs_put(cgrp->kn);
+ kfree(cgrp);
+ } else {
+ /*
+ * This is root cgroup's refcnt reaching zero,
+ * which indicates that the root should be
+ * released.
+ */
+ cgroup_destroy_root(cgrp->root);
+ }
+ }
+}
+
+static void css_free_rcu_fn(struct rcu_head *rcu_head)
+{
+ struct cgroup_subsys_state *css =
+ container_of(rcu_head, struct cgroup_subsys_state, rcu_head);
+
+ INIT_WORK(&css->destroy_work, css_free_work_fn);
+ queue_work(cgroup_destroy_wq, &css->destroy_work);
+}
+
+static void css_release_work_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+ struct cgroup_subsys *ss = css->ss;
+ struct cgroup *cgrp = css->cgroup;
+
+ mutex_lock(&cgroup_mutex);
+
+ css->flags |= CSS_RELEASED;
+ list_del_rcu(&css->sibling);
+
+ if (ss) {
+ /* css release path */
+ cgroup_idr_replace(&ss->css_idr, NULL, css->id);
+ if (ss->css_released)
+ ss->css_released(css);
+ } else {
+ /* cgroup release path */
+ trace_cgroup_release(cgrp);
+
+ cgroup_idr_remove(&cgrp->root->cgroup_idr, cgrp->id);
+ cgrp->id = -1;
+
+ /*
+ * There are two control paths which try to determine
+ * cgroup from dentry without going through kernfs -
+ * cgroupstats_build() and css_tryget_online_from_dir().
+ * Those are supported by RCU protecting clearing of
+ * cgrp->kn->priv backpointer.
+ */
+ if (cgrp->kn)
+ RCU_INIT_POINTER(*(void __rcu __force **)&cgrp->kn->priv,
+ NULL);
+
+ cgroup_bpf_put(cgrp);
+ }
+
+ mutex_unlock(&cgroup_mutex);
+
+ call_rcu(&css->rcu_head, css_free_rcu_fn);
+}
+
+static void css_release(struct percpu_ref *ref)
+{
+ struct cgroup_subsys_state *css =
+ container_of(ref, struct cgroup_subsys_state, refcnt);
+
+ INIT_WORK(&css->destroy_work, css_release_work_fn);
+ queue_work(cgroup_destroy_wq, &css->destroy_work);
+}
+
+static void init_and_link_css(struct cgroup_subsys_state *css,
+ struct cgroup_subsys *ss, struct cgroup *cgrp)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ cgroup_get(cgrp);
+
+ memset(css, 0, sizeof(*css));
+ css->cgroup = cgrp;
+ css->ss = ss;
+ css->id = -1;
+ INIT_LIST_HEAD(&css->sibling);
+ INIT_LIST_HEAD(&css->children);
+ css->serial_nr = css_serial_nr_next++;
+ atomic_set(&css->online_cnt, 0);
+
+ if (cgroup_parent(cgrp)) {
+ css->parent = cgroup_css(cgroup_parent(cgrp), ss);
+ css_get(css->parent);
+ }
+
+ BUG_ON(cgroup_css(cgrp, ss));
+}
+
+/* invoke ->css_online() on a new CSS and mark it online if successful */
+static int online_css(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys *ss = css->ss;
+ int ret = 0;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (ss->css_online)
+ ret = ss->css_online(css);
+ if (!ret) {
+ css->flags |= CSS_ONLINE;
+ rcu_assign_pointer(css->cgroup->subsys[ss->id], css);
+
+ atomic_inc(&css->online_cnt);
+ if (css->parent)
+ atomic_inc(&css->parent->online_cnt);
+ }
+ return ret;
+}
+
+/* if the CSS is online, invoke ->css_offline() on it and mark it offline */
+static void offline_css(struct cgroup_subsys_state *css)
+{
+ struct cgroup_subsys *ss = css->ss;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ if (!(css->flags & CSS_ONLINE))
+ return;
+
+ if (ss->css_reset)
+ ss->css_reset(css);
+
+ if (ss->css_offline)
+ ss->css_offline(css);
+
+ css->flags &= ~CSS_ONLINE;
+ RCU_INIT_POINTER(css->cgroup->subsys[ss->id], NULL);
+
+ wake_up_all(&css->cgroup->offline_waitq);
+}
+
+/**
+ * css_create - create a cgroup_subsys_state
+ * @cgrp: the cgroup new css will be associated with
+ * @ss: the subsys of new css
+ *
+ * Create a new css associated with @cgrp - @ss pair. On success, the new
+ * css is online and installed in @cgrp. This function doesn't create the
+ * interface files. Returns 0 on success, -errno on failure.
+ */
+static struct cgroup_subsys_state *css_create(struct cgroup *cgrp,
+ struct cgroup_subsys *ss)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+ struct cgroup_subsys_state *parent_css = cgroup_css(parent, ss);
+ struct cgroup_subsys_state *css;
+ int err;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ css = ss->css_alloc(parent_css);
+ if (!css)
+ css = ERR_PTR(-ENOMEM);
+ if (IS_ERR(css))
+ return css;
+
+ init_and_link_css(css, ss, cgrp);
+
+ err = percpu_ref_init(&css->refcnt, css_release, 0, GFP_KERNEL);
+ if (err)
+ goto err_free_css;
+
+ err = cgroup_idr_alloc(&ss->css_idr, NULL, 2, 0, GFP_KERNEL);
+ if (err < 0)
+ goto err_free_css;
+ css->id = err;
+
+ /* @css is ready to be brought online now, make it visible */
+ list_add_tail_rcu(&css->sibling, &parent_css->children);
+ cgroup_idr_replace(&ss->css_idr, css, css->id);
+
+ err = online_css(css);
+ if (err)
+ goto err_list_del;
+
+ if (ss->broken_hierarchy && !ss->warned_broken_hierarchy &&
+ cgroup_parent(parent)) {
+ pr_warn("%s (%d) created nested cgroup for controller \"%s\" which has incomplete hierarchy support. Nested cgroups may change behavior in the future.\n",
+ current->comm, current->pid, ss->name);
+ if (!strcmp(ss->name, "memory"))
+ pr_warn("\"memory\" requires setting use_hierarchy to 1 on the root\n");
+ ss->warned_broken_hierarchy = true;
+ }
+
+ return css;
+
+err_list_del:
+ list_del_rcu(&css->sibling);
+err_free_css:
+ call_rcu(&css->rcu_head, css_free_rcu_fn);
+ return ERR_PTR(err);
+}
+
+static struct cgroup *cgroup_create(struct cgroup *parent)
+{
+ struct cgroup_root *root = parent->root;
+ struct cgroup *cgrp, *tcgrp;
+ int level = parent->level + 1;
+ int ret;
+
+ /* allocate the cgroup and its ID, 0 is reserved for the root */
+ cgrp = kzalloc(sizeof(*cgrp) +
+ sizeof(cgrp->ancestor_ids[0]) * (level + 1), GFP_KERNEL);
+ if (!cgrp)
+ return ERR_PTR(-ENOMEM);
+
+ ret = percpu_ref_init(&cgrp->self.refcnt, css_release, 0, GFP_KERNEL);
+ if (ret)
+ goto out_free_cgrp;
+
+ /*
+ * Temporarily set the pointer to NULL, so idr_find() won't return
+ * a half-baked cgroup.
+ */
+ cgrp->id = cgroup_idr_alloc(&root->cgroup_idr, NULL, 2, 0, GFP_KERNEL);
+ if (cgrp->id < 0) {
+ ret = -ENOMEM;
+ goto out_cancel_ref;
+ }
+
+ init_cgroup_housekeeping(cgrp);
+
+ cgrp->self.parent = &parent->self;
+ cgrp->root = root;
+ cgrp->level = level;
+
+ for (tcgrp = cgrp; tcgrp; tcgrp = cgroup_parent(tcgrp))
+ cgrp->ancestor_ids[tcgrp->level] = tcgrp->id;
+
+ if (notify_on_release(parent))
+ set_bit(CGRP_NOTIFY_ON_RELEASE, &cgrp->flags);
+
+ if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &parent->flags))
+ set_bit(CGRP_CPUSET_CLONE_CHILDREN, &cgrp->flags);
+
+ cgrp->self.serial_nr = css_serial_nr_next++;
+
+ /* allocation complete, commit to creation */
+ list_add_tail_rcu(&cgrp->self.sibling, &cgroup_parent(cgrp)->self.children);
+ atomic_inc(&root->nr_cgrps);
+ cgroup_get(parent);
+
+ /*
+ * @cgrp is now fully operational. If something fails after this
+ * point, it'll be released via the normal destruction path.
+ */
+ cgroup_idr_replace(&root->cgroup_idr, cgrp, cgrp->id);
+
+ /*
+ * On the default hierarchy, a child doesn't automatically inherit
+ * subtree_control from the parent. Each is configured manually.
+ */
+ if (!cgroup_on_dfl(cgrp))
+ cgrp->subtree_control = cgroup_control(cgrp);
+
+ if (parent)
+ cgroup_bpf_inherit(cgrp, parent);
+
+ cgroup_propagate_control(cgrp);
+
+ /* @cgrp doesn't have dir yet so the following will only create csses */
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ goto out_destroy;
+
+ return cgrp;
+
+out_cancel_ref:
+ percpu_ref_exit(&cgrp->self.refcnt);
+out_free_cgrp:
+ kfree(cgrp);
+ return ERR_PTR(ret);
+out_destroy:
+ cgroup_destroy_locked(cgrp);
+ return ERR_PTR(ret);
+}
+
+static int cgroup_mkdir(struct kernfs_node *parent_kn, const char *name,
+ umode_t mode)
+{
+ struct cgroup *parent, *cgrp;
+ struct kernfs_node *kn;
+ int ret;
+
+ /* do not accept '\n' to prevent making /proc/<pid>/cgroup unparsable */
+ if (strchr(name, '\n'))
+ return -EINVAL;
+
+ parent = cgroup_kn_lock_live(parent_kn, false);
+ if (!parent)
+ return -ENODEV;
+
+ cgrp = cgroup_create(parent);
+ if (IS_ERR(cgrp)) {
+ ret = PTR_ERR(cgrp);
+ goto out_unlock;
+ }
+
+ /* create the directory */
+ kn = kernfs_create_dir(parent->kn, name, mode, cgrp);
+ if (IS_ERR(kn)) {
+ ret = PTR_ERR(kn);
+ goto out_destroy;
+ }
+ cgrp->kn = kn;
+
+ /*
+ * This extra ref will be put in cgroup_free_fn() and guarantees
+ * that @cgrp->kn is always accessible.
+ */
+ kernfs_get(kn);
+
+ ret = cgroup_kn_set_ugid(kn);
+ if (ret)
+ goto out_destroy;
+
+ ret = css_populate_dir(&cgrp->self);
+ if (ret)
+ goto out_destroy;
+
+ ret = cgroup_apply_control_enable(cgrp);
+ if (ret)
+ goto out_destroy;
+
+ trace_cgroup_mkdir(cgrp);
+
+ /* let's create and online css's */
+ kernfs_activate(kn);
+
+ ret = 0;
+ goto out_unlock;
+
+out_destroy:
+ cgroup_destroy_locked(cgrp);
+out_unlock:
+ cgroup_kn_unlock(parent_kn);
+ return ret;
+}
+
+/*
+ * This is called when the refcnt of a css is confirmed to be killed.
+ * css_tryget_online() is now guaranteed to fail. Tell the subsystem to
+ * initate destruction and put the css ref from kill_css().
+ */
+static void css_killed_work_fn(struct work_struct *work)
+{
+ struct cgroup_subsys_state *css =
+ container_of(work, struct cgroup_subsys_state, destroy_work);
+
+ mutex_lock(&cgroup_mutex);
+
+ do {
+ offline_css(css);
+ css_put(css);
+ /* @css can't go away while we're holding cgroup_mutex */
+ css = css->parent;
+ } while (css && atomic_dec_and_test(&css->online_cnt));
+
+ mutex_unlock(&cgroup_mutex);
+}
+
+/* css kill confirmation processing requires process context, bounce */
+static void css_killed_ref_fn(struct percpu_ref *ref)
+{
+ struct cgroup_subsys_state *css =
+ container_of(ref, struct cgroup_subsys_state, refcnt);
+
+ if (atomic_dec_and_test(&css->online_cnt)) {
+ INIT_WORK(&css->destroy_work, css_killed_work_fn);
+ queue_work(cgroup_destroy_wq, &css->destroy_work);
+ }
+}
+
+/**
+ * kill_css - destroy a css
+ * @css: css to destroy
+ *
+ * This function initiates destruction of @css by removing cgroup interface
+ * files and putting its base reference. ->css_offline() will be invoked
+ * asynchronously once css_tryget_online() is guaranteed to fail and when
+ * the reference count reaches zero, @css will be released.
+ */
+static void kill_css(struct cgroup_subsys_state *css)
+{
+ lockdep_assert_held(&cgroup_mutex);
+
+ /*
+ * This must happen before css is disassociated with its cgroup.
+ * See seq_css() for details.
+ */
+ css_clear_dir(css);
+
+ /*
+ * Killing would put the base ref, but we need to keep it alive
+ * until after ->css_offline().
+ */
+ css_get(css);
+
+ /*
+ * cgroup core guarantees that, by the time ->css_offline() is
+ * invoked, no new css reference will be given out via
+ * css_tryget_online(). We can't simply call percpu_ref_kill() and
+ * proceed to offlining css's because percpu_ref_kill() doesn't
+ * guarantee that the ref is seen as killed on all CPUs on return.
+ *
+ * Use percpu_ref_kill_and_confirm() to get notifications as each
+ * css is confirmed to be seen as killed on all CPUs.
+ */
+ percpu_ref_kill_and_confirm(&css->refcnt, css_killed_ref_fn);
+}
+
+/**
+ * cgroup_destroy_locked - the first stage of cgroup destruction
+ * @cgrp: cgroup to be destroyed
+ *
+ * css's make use of percpu refcnts whose killing latency shouldn't be
+ * exposed to userland and are RCU protected. Also, cgroup core needs to
+ * guarantee that css_tryget_online() won't succeed by the time
+ * ->css_offline() is invoked. To satisfy all the requirements,
+ * destruction is implemented in the following two steps.
+ *
+ * s1. Verify @cgrp can be destroyed and mark it dying. Remove all
+ * userland visible parts and start killing the percpu refcnts of
+ * css's. Set up so that the next stage will be kicked off once all
+ * the percpu refcnts are confirmed to be killed.
+ *
+ * s2. Invoke ->css_offline(), mark the cgroup dead and proceed with the
+ * rest of destruction. Once all cgroup references are gone, the
+ * cgroup is RCU-freed.
+ *
+ * This function implements s1. After this step, @cgrp is gone as far as
+ * the userland is concerned and a new cgroup with the same name may be
+ * created. As cgroup doesn't care about the names internally, this
+ * doesn't cause any problem.
+ */
+static int cgroup_destroy_locked(struct cgroup *cgrp)
+ __releases(&cgroup_mutex) __acquires(&cgroup_mutex)
+{
+ struct cgroup_subsys_state *css;
+ struct cgrp_cset_link *link;
+ int ssid;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ /*
+ * Only migration can raise populated from zero and we're already
+ * holding cgroup_mutex.
+ */
+ if (cgroup_is_populated(cgrp))
+ return -EBUSY;
+
+ /*
+ * Make sure there's no live children. We can't test emptiness of
+ * ->self.children as dead children linger on it while being
+ * drained; otherwise, "rmdir parent/child parent" may fail.
+ */
+ if (css_has_online_children(&cgrp->self))
+ return -EBUSY;
+
+ /*
+ * Mark @cgrp and the associated csets dead. The former prevents
+ * further task migration and child creation by disabling
+ * cgroup_lock_live_group(). The latter makes the csets ignored by
+ * the migration path.
+ */
+ cgrp->self.flags &= ~CSS_ONLINE;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &cgrp->cset_links, cset_link)
+ link->cset->dead = true;
+ spin_unlock_irq(&css_set_lock);
+
+ /* initiate massacre of all css's */
+ for_each_css(css, ssid, cgrp)
+ kill_css(css);
+
+ /*
+ * Remove @cgrp directory along with the base files. @cgrp has an
+ * extra ref on its kn.
+ */
+ kernfs_remove(cgrp->kn);
+
+ check_for_release(cgroup_parent(cgrp));
+
+ /* put the base reference */
+ percpu_ref_kill(&cgrp->self.refcnt);
+
+ return 0;
+};
+
+static int cgroup_rmdir(struct kernfs_node *kn)
+{
+ struct cgroup *cgrp;
+ int ret = 0;
+
+ cgrp = cgroup_kn_lock_live(kn, false);
+ if (!cgrp)
+ return 0;
+
+ ret = cgroup_destroy_locked(cgrp);
+
+ if (!ret)
+ trace_cgroup_rmdir(cgrp);
+
+ cgroup_kn_unlock(kn);
+ return ret;
+}
+
+static struct kernfs_syscall_ops cgroup_kf_syscall_ops = {
+ .remount_fs = cgroup_remount,
+ .show_options = cgroup_show_options,
+ .mkdir = cgroup_mkdir,
+ .rmdir = cgroup_rmdir,
+ .rename = cgroup_rename,
+ .show_path = cgroup_show_path,
+};
+
+static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early)
+{
+ struct cgroup_subsys_state *css;
+
+ pr_debug("Initializing cgroup subsys %s\n", ss->name);
+
+ mutex_lock(&cgroup_mutex);
+
+ idr_init(&ss->css_idr);
+ INIT_LIST_HEAD(&ss->cfts);
+
+ /* Create the root cgroup state for this subsystem */
+ ss->root = &cgrp_dfl_root;
+ css = ss->css_alloc(cgroup_css(&cgrp_dfl_root.cgrp, ss));
+ /* We don't handle early failures gracefully */
+ BUG_ON(IS_ERR(css));
+ init_and_link_css(css, ss, &cgrp_dfl_root.cgrp);
+
+ /*
+ * Root csses are never destroyed and we can't initialize
+ * percpu_ref during early init. Disable refcnting.
+ */
+ css->flags |= CSS_NO_REF;
+
+ if (early) {
+ /* allocation can't be done safely during early init */
+ css->id = 1;
+ } else {
+ css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2, GFP_KERNEL);
+ BUG_ON(css->id < 0);
+ }
+
+ /* Update the init_css_set to contain a subsys
+ * pointer to this state - since the subsystem is
+ * newly registered, all tasks and hence the
+ * init_css_set is in the subsystem's root cgroup. */
+ init_css_set.subsys[ss->id] = css;
+
+ have_fork_callback |= (bool)ss->fork << ss->id;
+ have_exit_callback |= (bool)ss->exit << ss->id;
+ have_free_callback |= (bool)ss->free << ss->id;
+ have_canfork_callback |= (bool)ss->can_fork << ss->id;
+
+ /* At system boot, before all subsystems have been
+ * registered, no tasks have been forked, so we don't
+ * need to invoke fork callbacks here. */
+ BUG_ON(!list_empty(&init_task.tasks));
+
+ BUG_ON(online_css(css));
+
+ mutex_unlock(&cgroup_mutex);
+}
+
+/**
+ * cgroup_init_early - cgroup initialization at system boot
+ *
+ * Initialize cgroups at system boot, and initialize any
+ * subsystems that request early init.
+ */
+int __init cgroup_init_early(void)
+{
+ static struct cgroup_sb_opts __initdata opts;
+ struct cgroup_subsys *ss;
+ int i;
+
+ init_cgroup_root(&cgrp_dfl_root, &opts);
+ cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;
+
+ RCU_INIT_POINTER(init_task.cgroups, &init_css_set);
+
+ for_each_subsys(ss, i) {
+ WARN(!ss->css_alloc || !ss->css_free || ss->name || ss->id,
+ "invalid cgroup_subsys %d:%s css_alloc=%p css_free=%p id:name=%d:%s\n",
+ i, cgroup_subsys_name[i], ss->css_alloc, ss->css_free,
+ ss->id, ss->name);
+ WARN(strlen(cgroup_subsys_name[i]) > MAX_CGROUP_TYPE_NAMELEN,
+ "cgroup_subsys_name %s too long\n", cgroup_subsys_name[i]);
+
+ ss->id = i;
+ ss->name = cgroup_subsys_name[i];
+ if (!ss->legacy_name)
+ ss->legacy_name = cgroup_subsys_name[i];
+
+ if (ss->early_init)
+ cgroup_init_subsys(ss, true);
+ }
+ return 0;
+}
+
+static u16 cgroup_disable_mask __initdata;
+
+/**
+ * cgroup_init - cgroup initialization
+ *
+ * Register cgroup filesystem and /proc file, and initialize
+ * any subsystems that didn't request early init.
+ */
+int __init cgroup_init(void)
+{
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ BUILD_BUG_ON(CGROUP_SUBSYS_COUNT > 16);
+ BUG_ON(percpu_init_rwsem(&cgroup_threadgroup_rwsem));
+ BUG_ON(cgroup_init_cftypes(NULL, cgroup_dfl_base_files));
+ BUG_ON(cgroup_init_cftypes(NULL, cgroup_legacy_base_files));
+
+ /*
+ * The latency of the synchronize_sched() is too high for cgroups,
+ * avoid it at the cost of forcing all readers into the slow path.
+ */
+ rcu_sync_enter_start(&cgroup_threadgroup_rwsem.rss);
+
+ get_user_ns(init_cgroup_ns.user_ns);
+
+ mutex_lock(&cgroup_mutex);
+
+ /*
+ * Add init_css_set to the hash table so that dfl_root can link to
+ * it during init.
+ */
+ hash_add(css_set_table, &init_css_set.hlist,
+ css_set_hash(init_css_set.subsys));
+
+ BUG_ON(cgroup_setup_root(&cgrp_dfl_root, 0));
+
+ mutex_unlock(&cgroup_mutex);
+
+ for_each_subsys(ss, ssid) {
+ if (ss->early_init) {
+ struct cgroup_subsys_state *css =
+ init_css_set.subsys[ss->id];
+
+ css->id = cgroup_idr_alloc(&ss->css_idr, css, 1, 2,
+ GFP_KERNEL);
+ BUG_ON(css->id < 0);
+ } else {
+ cgroup_init_subsys(ss, false);
+ }
+
+ list_add_tail(&init_css_set.e_cset_node[ssid],
+ &cgrp_dfl_root.cgrp.e_csets[ssid]);
+
+ /*
+ * Setting dfl_root subsys_mask needs to consider the
+ * disabled flag and cftype registration needs kmalloc,
+ * both of which aren't available during early_init.
+ */
+ if (cgroup_disable_mask & (1 << ssid)) {
+ static_branch_disable(cgroup_subsys_enabled_key[ssid]);
+ printk(KERN_INFO "Disabling %s control group subsystem\n",
+ ss->name);
+ continue;
+ }
+
+ if (cgroup_ssid_no_v1(ssid))
+ printk(KERN_INFO "Disabling %s control group subsystem in v1 mounts\n",
+ ss->name);
+
+ cgrp_dfl_root.subsys_mask |= 1 << ss->id;
+
+ if (ss->implicit_on_dfl)
+ cgrp_dfl_implicit_ss_mask |= 1 << ss->id;
+ else if (!ss->dfl_cftypes)
+ cgrp_dfl_inhibit_ss_mask |= 1 << ss->id;
+
+ if (ss->dfl_cftypes == ss->legacy_cftypes) {
+ WARN_ON(cgroup_add_cftypes(ss, ss->dfl_cftypes));
+ } else {
+ WARN_ON(cgroup_add_dfl_cftypes(ss, ss->dfl_cftypes));
+ WARN_ON(cgroup_add_legacy_cftypes(ss, ss->legacy_cftypes));
+ }
+
+ if (ss->bind)
+ ss->bind(init_css_set.subsys[ssid]);
+ }
+
+ /* init_css_set.subsys[] has been updated, re-hash */
+ hash_del(&init_css_set.hlist);
+ hash_add(css_set_table, &init_css_set.hlist,
+ css_set_hash(init_css_set.subsys));
+
+ WARN_ON(sysfs_create_mount_point(fs_kobj, "cgroup"));
+ WARN_ON(register_filesystem(&cgroup_fs_type));
+ WARN_ON(register_filesystem(&cgroup2_fs_type));
+ WARN_ON(!proc_create("cgroups", 0, NULL, &proc_cgroupstats_operations));
+
+ return 0;
+}
+
+static int __init cgroup_wq_init(void)
+{
+ /*
+ * There isn't much point in executing destruction path in
+ * parallel. Good chunk is serialized with cgroup_mutex anyway.
+ * Use 1 for @max_active.
+ *
+ * We would prefer to do this in cgroup_init() above, but that
+ * is called before init_workqueues(): so leave this until after.
+ */
+ cgroup_destroy_wq = alloc_workqueue("cgroup_destroy", 0, 1);
+ BUG_ON(!cgroup_destroy_wq);
+
+ /*
+ * Used to destroy pidlists and separate to serve as flush domain.
+ * Cap @max_active to 1 too.
+ */
+ cgroup_pidlist_destroy_wq = alloc_workqueue("cgroup_pidlist_destroy",
+ 0, 1);
+ BUG_ON(!cgroup_pidlist_destroy_wq);
+
+ return 0;
+}
+core_initcall(cgroup_wq_init);
+
+/*
+ * proc_cgroup_show()
+ * - Print task's cgroup paths into seq_file, one line for each hierarchy
+ * - Used for /proc/<pid>/cgroup.
+ */
+int proc_cgroup_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ char *buf;
+ int retval;
+ struct cgroup_root *root;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ mutex_lock(&cgroup_mutex);
+ spin_lock_irq(&css_set_lock);
+
+ for_each_root(root) {
+ struct cgroup_subsys *ss;
+ struct cgroup *cgrp;
+ int ssid, count = 0;
+
+ if (root == &cgrp_dfl_root && !cgrp_dfl_visible)
+ continue;
+
+ seq_printf(m, "%d:", root->hierarchy_id);
+ if (root != &cgrp_dfl_root)
+ for_each_subsys(ss, ssid)
+ if (root->subsys_mask & (1 << ssid))
+ seq_printf(m, "%s%s", count++ ? "," : "",
+ ss->legacy_name);
+ if (strlen(root->name))
+ seq_printf(m, "%sname=%s", count ? "," : "",
+ root->name);
+ seq_putc(m, ':');
+
+ cgrp = task_cgroup_from_root(tsk, root);
+
+ /*
+ * On traditional hierarchies, all zombie tasks show up as
+ * belonging to the root cgroup. On the default hierarchy,
+ * while a zombie doesn't show up in "cgroup.procs" and
+ * thus can't be migrated, its /proc/PID/cgroup keeps
+ * reporting the cgroup it belonged to before exiting. If
+ * the cgroup is removed before the zombie is reaped,
+ * " (deleted)" is appended to the cgroup path.
+ */
+ if (cgroup_on_dfl(cgrp) || !(tsk->flags & PF_EXITING)) {
+ retval = cgroup_path_ns_locked(cgrp, buf, PATH_MAX,
+ current->nsproxy->cgroup_ns);
+ if (retval >= PATH_MAX)
+ retval = -ENAMETOOLONG;
+ if (retval < 0)
+ goto out_unlock;
+
+ seq_puts(m, buf);
+ } else {
+ seq_puts(m, "/");
+ }
+
+ if (cgroup_on_dfl(cgrp) && cgroup_is_dead(cgrp))
+ seq_puts(m, " (deleted)\n");
+ else
+ seq_putc(m, '\n');
+ }
+
+ retval = 0;
+out_unlock:
+ spin_unlock_irq(&css_set_lock);
+ mutex_unlock(&cgroup_mutex);
+ kfree(buf);
+out:
+ return retval;
+}
+
+/* Display information about each subsystem and each hierarchy */
+static int proc_cgroupstats_show(struct seq_file *m, void *v)
+{
+ struct cgroup_subsys *ss;
+ int i;
+
+ seq_puts(m, "#subsys_name\thierarchy\tnum_cgroups\tenabled\n");
+ /*
+ * ideally we don't want subsystems moving around while we do this.
+ * cgroup_mutex is also necessary to guarantee an atomic snapshot of
+ * subsys/hierarchy state.
+ */
+ mutex_lock(&cgroup_mutex);
+
+ for_each_subsys(ss, i)
+ seq_printf(m, "%s\t%d\t%d\t%d\n",
+ ss->legacy_name, ss->root->hierarchy_id,
+ atomic_read(&ss->root->nr_cgrps),
+ cgroup_ssid_enabled(i));
+
+ mutex_unlock(&cgroup_mutex);
+ return 0;
+}
+
+static int cgroupstats_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, proc_cgroupstats_show, NULL);
+}
+
+static const struct file_operations proc_cgroupstats_operations = {
+ .open = cgroupstats_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+/**
+ * cgroup_fork - initialize cgroup related fields during copy_process()
+ * @child: pointer to task_struct of forking parent process.
+ *
+ * A task is associated with the init_css_set until cgroup_post_fork()
+ * attaches it to the parent's css_set. Empty cg_list indicates that
+ * @child isn't holding reference to its css_set.
+ */
+void cgroup_fork(struct task_struct *child)
+{
+ RCU_INIT_POINTER(child->cgroups, &init_css_set);
+ INIT_LIST_HEAD(&child->cg_list);
+}
+
+/**
+ * cgroup_can_fork - called on a new task before the process is exposed
+ * @child: the task in question.
+ *
+ * This calls the subsystem can_fork() callbacks. If the can_fork() callback
+ * returns an error, the fork aborts with that error code. This allows for
+ * a cgroup subsystem to conditionally allow or deny new forks.
+ */
+int cgroup_can_fork(struct task_struct *child)
+{
+ struct cgroup_subsys *ss;
+ int i, j, ret;
+
+ do_each_subsys_mask(ss, i, have_canfork_callback) {
+ ret = ss->can_fork(child);
+ if (ret)
+ goto out_revert;
+ } while_each_subsys_mask();
+
+ return 0;
+
+out_revert:
+ for_each_subsys(ss, j) {
+ if (j >= i)
+ break;
+ if (ss->cancel_fork)
+ ss->cancel_fork(child);
+ }
+
+ return ret;
+}
+
+/**
+ * cgroup_cancel_fork - called if a fork failed after cgroup_can_fork()
+ * @child: the task in question
+ *
+ * This calls the cancel_fork() callbacks if a fork failed *after*
+ * cgroup_can_fork() succeded.
+ */
+void cgroup_cancel_fork(struct task_struct *child)
+{
+ struct cgroup_subsys *ss;
+ int i;
+
+ for_each_subsys(ss, i)
+ if (ss->cancel_fork)
+ ss->cancel_fork(child);
+}
+
+/**
+ * cgroup_post_fork - called on a new task after adding it to the task list
+ * @child: the task in question
+ *
+ * Adds the task to the list running through its css_set if necessary and
+ * call the subsystem fork() callbacks. Has to be after the task is
+ * visible on the task list in case we race with the first call to
+ * cgroup_task_iter_start() - to guarantee that the new task ends up on its
+ * list.
+ */
+void cgroup_post_fork(struct task_struct *child)
+{
+ struct cgroup_subsys *ss;
+ int i;
+
+ /*
+ * This may race against cgroup_enable_task_cg_lists(). As that
+ * function sets use_task_css_set_links before grabbing
+ * tasklist_lock and we just went through tasklist_lock to add
+ * @child, it's guaranteed that either we see the set
+ * use_task_css_set_links or cgroup_enable_task_cg_lists() sees
+ * @child during its iteration.
+ *
+ * If we won the race, @child is associated with %current's
+ * css_set. Grabbing css_set_lock guarantees both that the
+ * association is stable, and, on completion of the parent's
+ * migration, @child is visible in the source of migration or
+ * already in the destination cgroup. This guarantee is necessary
+ * when implementing operations which need to migrate all tasks of
+ * a cgroup to another.
+ *
+ * Note that if we lose to cgroup_enable_task_cg_lists(), @child
+ * will remain in init_css_set. This is safe because all tasks are
+ * in the init_css_set before cg_links is enabled and there's no
+ * operation which transfers all tasks out of init_css_set.
+ */
+ if (use_task_css_set_links) {
+ struct css_set *cset;
+
+ spin_lock_irq(&css_set_lock);
+ cset = task_css_set(current);
+ if (list_empty(&child->cg_list)) {
+ get_css_set(cset);
+ css_set_move_task(child, NULL, cset, false);
+ }
+ spin_unlock_irq(&css_set_lock);
+ }
+
+ /*
+ * Call ss->fork(). This must happen after @child is linked on
+ * css_set; otherwise, @child might change state between ->fork()
+ * and addition to css_set.
+ */
+ do_each_subsys_mask(ss, i, have_fork_callback) {
+ ss->fork(child);
+ } while_each_subsys_mask();
+}
+
+/**
+ * cgroup_exit - detach cgroup from exiting task
+ * @tsk: pointer to task_struct of exiting process
+ *
+ * Description: Detach cgroup from @tsk and release it.
+ *
+ * Note that cgroups marked notify_on_release force every task in
+ * them to take the global cgroup_mutex mutex when exiting.
+ * This could impact scaling on very large systems. Be reluctant to
+ * use notify_on_release cgroups where very high task exit scaling
+ * is required on large systems.
+ *
+ * We set the exiting tasks cgroup to the root cgroup (top_cgroup). We
+ * call cgroup_exit() while the task is still competent to handle
+ * notify_on_release(), then leave the task attached to the root cgroup in
+ * each hierarchy for the remainder of its exit. No need to bother with
+ * init_css_set refcnting. init_css_set never goes away and we can't race
+ * with migration path - PF_EXITING is visible to migration path.
+ */
+void cgroup_exit(struct task_struct *tsk)
+{
+ struct cgroup_subsys *ss;
+ struct css_set *cset;
+ int i;
+
+ /*
+ * Unlink from @tsk from its css_set. As migration path can't race
+ * with us, we can check css_set and cg_list without synchronization.
+ */
+ cset = task_css_set(tsk);
+
+ if (!list_empty(&tsk->cg_list)) {
+ spin_lock_irq(&css_set_lock);
+ css_set_move_task(tsk, cset, NULL, false);
+ spin_unlock_irq(&css_set_lock);
+ } else {
+ get_css_set(cset);
+ }
+
+ /* see cgroup_post_fork() for details */
+ do_each_subsys_mask(ss, i, have_exit_callback) {
+ ss->exit(tsk);
+ } while_each_subsys_mask();
+}
+
+void cgroup_free(struct task_struct *task)
+{
+ struct css_set *cset = task_css_set(task);
+ struct cgroup_subsys *ss;
+ int ssid;
+
+ do_each_subsys_mask(ss, ssid, have_free_callback) {
+ ss->free(task);
+ } while_each_subsys_mask();
+
+ put_css_set(cset);
+}
+
+static void check_for_release(struct cgroup *cgrp)
+{
+ if (notify_on_release(cgrp) && !cgroup_is_populated(cgrp) &&
+ !css_has_online_children(&cgrp->self) && !cgroup_is_dead(cgrp))
+ schedule_work(&cgrp->release_agent_work);
+}
+
+/*
+ * Notify userspace when a cgroup is released, by running the
+ * configured release agent with the name of the cgroup (path
+ * relative to the root of cgroup file system) as the argument.
+ *
+ * Most likely, this user command will try to rmdir this cgroup.
+ *
+ * This races with the possibility that some other task will be
+ * attached to this cgroup before it is removed, or that some other
+ * user task will 'mkdir' a child cgroup of this cgroup. That's ok.
+ * The presumed 'rmdir' will fail quietly if this cgroup is no longer
+ * unused, and this cgroup will be reprieved from its death sentence,
+ * to continue to serve a useful existence. Next time it's released,
+ * we will get notified again, if it still has 'notify_on_release' set.
+ *
+ * The final arg to call_usermodehelper() is UMH_WAIT_EXEC, which
+ * means only wait until the task is successfully execve()'d. The
+ * separate release agent task is forked by call_usermodehelper(),
+ * then control in this thread returns here, without waiting for the
+ * release agent task. We don't bother to wait because the caller of
+ * this routine has no use for the exit status of the release agent
+ * task, so no sense holding our caller up for that.
+ */
+static void cgroup_release_agent(struct work_struct *work)
+{
+ struct cgroup *cgrp =
+ container_of(work, struct cgroup, release_agent_work);
+ char *pathbuf = NULL, *agentbuf = NULL;
+ char *argv[3], *envp[3];
+ int ret;
+
+ mutex_lock(&cgroup_mutex);
+
+ pathbuf = kmalloc(PATH_MAX, GFP_KERNEL);
+ agentbuf = kstrdup(cgrp->root->release_agent_path, GFP_KERNEL);
+ if (!pathbuf || !agentbuf)
+ goto out;
+
+ spin_lock_irq(&css_set_lock);
+ ret = cgroup_path_ns_locked(cgrp, pathbuf, PATH_MAX, &init_cgroup_ns);
+ spin_unlock_irq(&css_set_lock);
+ if (ret < 0 || ret >= PATH_MAX)
+ goto out;
+
+ argv[0] = agentbuf;
+ argv[1] = pathbuf;
+ argv[2] = NULL;
+
+ /* minimal command environment */
+ envp[0] = "HOME=/";
+ envp[1] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+ envp[2] = NULL;
+
+ mutex_unlock(&cgroup_mutex);
+ call_usermodehelper(argv[0], argv, envp, UMH_WAIT_EXEC);
+ goto out_free;
+out:
+ mutex_unlock(&cgroup_mutex);
+out_free:
+ kfree(agentbuf);
+ kfree(pathbuf);
+}
+
+static int __init cgroup_disable(char *str)
+{
+ struct cgroup_subsys *ss;
+ char *token;
+ int i;
+
+ while ((token = strsep(&str, ",")) != NULL) {
+ if (!*token)
+ continue;
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->name) &&
+ strcmp(token, ss->legacy_name))
+ continue;
+ cgroup_disable_mask |= 1 << i;
+ }
+ }
+ return 1;
+}
+__setup("cgroup_disable=", cgroup_disable);
+
+static int __init cgroup_no_v1(char *str)
+{
+ struct cgroup_subsys *ss;
+ char *token;
+ int i;
+
+ while ((token = strsep(&str, ",")) != NULL) {
+ if (!*token)
+ continue;
+
+ if (!strcmp(token, "all")) {
+ cgroup_no_v1_mask = U16_MAX;
+ break;
+ }
+
+ for_each_subsys(ss, i) {
+ if (strcmp(token, ss->name) &&
+ strcmp(token, ss->legacy_name))
+ continue;
+
+ cgroup_no_v1_mask |= 1 << i;
+ }
+ }
+ return 1;
+}
+__setup("cgroup_no_v1=", cgroup_no_v1);
+
+/**
+ * css_tryget_online_from_dir - get corresponding css from a cgroup dentry
+ * @dentry: directory dentry of interest
+ * @ss: subsystem of interest
+ *
+ * If @dentry is a directory for a cgroup which has @ss enabled on it, try
+ * to get the corresponding css and return it. If such css doesn't exist
+ * or can't be pinned, an ERR_PTR value is returned.
+ */
+struct cgroup_subsys_state *css_tryget_online_from_dir(struct dentry *dentry,
+ struct cgroup_subsys *ss)
+{
+ struct kernfs_node *kn = kernfs_node_from_dentry(dentry);
+ struct file_system_type *s_type = dentry->d_sb->s_type;
+ struct cgroup_subsys_state *css = NULL;
+ struct cgroup *cgrp;
+
+ /* is @dentry a cgroup dir? */
+ if ((s_type != &cgroup_fs_type && s_type != &cgroup2_fs_type) ||
+ !kn || kernfs_type(kn) != KERNFS_DIR)
+ return ERR_PTR(-EBADF);
+
+ rcu_read_lock();
+
+ /*
+ * This path doesn't originate from kernfs and @kn could already
+ * have been or be removed at any point. @kn->priv is RCU
+ * protected for this access. See css_release_work_fn() for details.
+ */
+ cgrp = rcu_dereference(kn->priv);
+ if (cgrp)
+ css = cgroup_css(cgrp, ss);
+
+ if (!css || !css_tryget_online(css))
+ css = ERR_PTR(-ENOENT);
+
+ rcu_read_unlock();
+ return css;
+}
+
+/**
+ * css_from_id - lookup css by id
+ * @id: the cgroup id
+ * @ss: cgroup subsys to be looked into
+ *
+ * Returns the css if there's valid one with @id, otherwise returns NULL.
+ * Should be called under rcu_read_lock().
+ */
+struct cgroup_subsys_state *css_from_id(int id, struct cgroup_subsys *ss)
+{
+ WARN_ON_ONCE(!rcu_read_lock_held());
+ return idr_find(&ss->css_idr, id);
+}
+
+/**
+ * cgroup_get_from_path - lookup and get a cgroup from its default hierarchy path
+ * @path: path on the default hierarchy
+ *
+ * Find the cgroup at @path on the default hierarchy, increment its
+ * reference count and return it. Returns pointer to the found cgroup on
+ * success, ERR_PTR(-ENOENT) if @path doens't exist and ERR_PTR(-ENOTDIR)
+ * if @path points to a non-directory.
+ */
+struct cgroup *cgroup_get_from_path(const char *path)
+{
+ struct kernfs_node *kn;
+ struct cgroup *cgrp;
+
+ mutex_lock(&cgroup_mutex);
+
+ kn = kernfs_walk_and_get(cgrp_dfl_root.cgrp.kn, path);
+ if (kn) {
+ if (kernfs_type(kn) == KERNFS_DIR) {
+ cgrp = kn->priv;
+ cgroup_get(cgrp);
+ } else {
+ cgrp = ERR_PTR(-ENOTDIR);
+ }
+ kernfs_put(kn);
+ } else {
+ cgrp = ERR_PTR(-ENOENT);
+ }
+
+ mutex_unlock(&cgroup_mutex);
+ return cgrp;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_from_path);
+
+/**
+ * cgroup_get_from_fd - get a cgroup pointer from a fd
+ * @fd: fd obtained by open(cgroup2_dir)
+ *
+ * Find the cgroup from a fd which should be obtained
+ * by opening a cgroup directory. Returns a pointer to the
+ * cgroup on success. ERR_PTR is returned if the cgroup
+ * cannot be found.
+ */
+struct cgroup *cgroup_get_from_fd(int fd)
+{
+ struct cgroup_subsys_state *css;
+ struct cgroup *cgrp;
+ struct file *f;
+
+ f = fget_raw(fd);
+ if (!f)
+ return ERR_PTR(-EBADF);
+
+ css = css_tryget_online_from_dir(f->f_path.dentry, NULL);
+ fput(f);
+ if (IS_ERR(css))
+ return ERR_CAST(css);
+
+ cgrp = css->cgroup;
+ if (!cgroup_on_dfl(cgrp)) {
+ cgroup_put(cgrp);
+ return ERR_PTR(-EBADF);
+ }
+
+ return cgrp;
+}
+EXPORT_SYMBOL_GPL(cgroup_get_from_fd);
+
+/*
+ * sock->sk_cgrp_data handling. For more info, see sock_cgroup_data
+ * definition in cgroup-defs.h.
+ */
+#ifdef CONFIG_SOCK_CGROUP_DATA
+
+#if defined(CONFIG_CGROUP_NET_PRIO) || defined(CONFIG_CGROUP_NET_CLASSID)
+
+DEFINE_SPINLOCK(cgroup_sk_update_lock);
+static bool cgroup_sk_alloc_disabled __read_mostly;
+
+void cgroup_sk_alloc_disable(void)
+{
+ if (cgroup_sk_alloc_disabled)
+ return;
+ pr_info("cgroup: disabling cgroup2 socket matching due to net_prio or net_cls activation\n");
+ cgroup_sk_alloc_disabled = true;
+}
+
+#else
+
+#define cgroup_sk_alloc_disabled false
+
+#endif
+
+void cgroup_sk_alloc(struct sock_cgroup_data *skcd)
+{
+ if (cgroup_sk_alloc_disabled)
+ return;
+
+ /* Socket clone path */
+ if (skcd->val) {
+ cgroup_get(sock_cgroup_ptr(skcd));
+ return;
+ }
+
+ rcu_read_lock();
+
+ while (true) {
+ struct css_set *cset;
+
+ cset = task_css_set(current);
+ if (likely(cgroup_tryget(cset->dfl_cgrp))) {
+ skcd->val = (unsigned long)cset->dfl_cgrp;
+ break;
+ }
+ cpu_relax();
+ }
+
+ rcu_read_unlock();
+}
+
+void cgroup_sk_free(struct sock_cgroup_data *skcd)
+{
+ cgroup_put(sock_cgroup_ptr(skcd));
+}
+
+#endif /* CONFIG_SOCK_CGROUP_DATA */
+
+/* cgroup namespaces */
+
+static struct ucounts *inc_cgroup_namespaces(struct user_namespace *ns)
+{
+ return inc_ucount(ns, current_euid(), UCOUNT_CGROUP_NAMESPACES);
+}
+
+static void dec_cgroup_namespaces(struct ucounts *ucounts)
+{
+ dec_ucount(ucounts, UCOUNT_CGROUP_NAMESPACES);
+}
+
+static struct cgroup_namespace *alloc_cgroup_ns(void)
+{
+ struct cgroup_namespace *new_ns;
+ int ret;
+
+ new_ns = kzalloc(sizeof(struct cgroup_namespace), GFP_KERNEL);
+ if (!new_ns)
+ return ERR_PTR(-ENOMEM);
+ ret = ns_alloc_inum(&new_ns->ns);
+ if (ret) {
+ kfree(new_ns);
+ return ERR_PTR(ret);
+ }
+ atomic_set(&new_ns->count, 1);
+ new_ns->ns.ops = &cgroupns_operations;
+ return new_ns;
+}
+
+void free_cgroup_ns(struct cgroup_namespace *ns)
+{
+ put_css_set(ns->root_cset);
+ dec_cgroup_namespaces(ns->ucounts);
+ put_user_ns(ns->user_ns);
+ ns_free_inum(&ns->ns);
+ kfree(ns);
+}
+EXPORT_SYMBOL(free_cgroup_ns);
+
+struct cgroup_namespace *copy_cgroup_ns(unsigned long flags,
+ struct user_namespace *user_ns,
+ struct cgroup_namespace *old_ns)
+{
+ struct cgroup_namespace *new_ns;
+ struct ucounts *ucounts;
+ struct css_set *cset;
+
+ BUG_ON(!old_ns);
+
+ if (!(flags & CLONE_NEWCGROUP)) {
+ get_cgroup_ns(old_ns);
+ return old_ns;
+ }
+
+ /* Allow only sysadmin to create cgroup namespace. */
+ if (!ns_capable(user_ns, CAP_SYS_ADMIN))
+ return ERR_PTR(-EPERM);
+
+ ucounts = inc_cgroup_namespaces(user_ns);
+ if (!ucounts)
+ return ERR_PTR(-ENOSPC);
+
+ /* It is not safe to take cgroup_mutex here */
+ spin_lock_irq(&css_set_lock);
+ cset = task_css_set(current);
+ get_css_set(cset);
+ spin_unlock_irq(&css_set_lock);
+
+ new_ns = alloc_cgroup_ns();
+ if (IS_ERR(new_ns)) {
+ put_css_set(cset);
+ dec_cgroup_namespaces(ucounts);
+ return new_ns;
+ }
+
+ new_ns->user_ns = get_user_ns(user_ns);
+ new_ns->ucounts = ucounts;
+ new_ns->root_cset = cset;
+
+ return new_ns;
+}
+
+static inline struct cgroup_namespace *to_cg_ns(struct ns_common *ns)
+{
+ return container_of(ns, struct cgroup_namespace, ns);
+}
+
+static int cgroupns_install(struct nsproxy *nsproxy, struct ns_common *ns)
+{
+ struct cgroup_namespace *cgroup_ns = to_cg_ns(ns);
+
+ if (!ns_capable(current_user_ns(), CAP_SYS_ADMIN) ||
+ !ns_capable(cgroup_ns->user_ns, CAP_SYS_ADMIN))
+ return -EPERM;
+
+ /* Don't need to do anything if we are attaching to our own cgroupns. */
+ if (cgroup_ns == nsproxy->cgroup_ns)
+ return 0;
+
+ get_cgroup_ns(cgroup_ns);
+ put_cgroup_ns(nsproxy->cgroup_ns);
+ nsproxy->cgroup_ns = cgroup_ns;
+
+ return 0;
+}
+
+static struct ns_common *cgroupns_get(struct task_struct *task)
+{
+ struct cgroup_namespace *ns = NULL;
+ struct nsproxy *nsproxy;
+
+ task_lock(task);
+ nsproxy = task->nsproxy;
+ if (nsproxy) {
+ ns = nsproxy->cgroup_ns;
+ get_cgroup_ns(ns);
+ }
+ task_unlock(task);
+
+ return ns ? &ns->ns : NULL;
+}
+
+static void cgroupns_put(struct ns_common *ns)
+{
+ put_cgroup_ns(to_cg_ns(ns));
+}
+
+static struct user_namespace *cgroupns_owner(struct ns_common *ns)
+{
+ return to_cg_ns(ns)->user_ns;
+}
+
+const struct proc_ns_operations cgroupns_operations = {
+ .name = "cgroup",
+ .type = CLONE_NEWCGROUP,
+ .get = cgroupns_get,
+ .put = cgroupns_put,
+ .install = cgroupns_install,
+ .owner = cgroupns_owner,
+};
+
+static __init int cgroup_namespaces_init(void)
+{
+ return 0;
+}
+subsys_initcall(cgroup_namespaces_init);
+
+#ifdef CONFIG_CGROUP_BPF
+void cgroup_bpf_update(struct cgroup *cgrp,
+ struct bpf_prog *prog,
+ enum bpf_attach_type type)
+{
+ struct cgroup *parent = cgroup_parent(cgrp);
+
+ mutex_lock(&cgroup_mutex);
+ __cgroup_bpf_update(cgrp, parent, prog, type);
+ mutex_unlock(&cgroup_mutex);
+}
+#endif /* CONFIG_CGROUP_BPF */
+
+#ifdef CONFIG_CGROUP_DEBUG
+static struct cgroup_subsys_state *
+debug_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct cgroup_subsys_state *css = kzalloc(sizeof(*css), GFP_KERNEL);
+
+ if (!css)
+ return ERR_PTR(-ENOMEM);
+
+ return css;
+}
+
+static void debug_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css);
+}
+
+static u64 debug_taskcount_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return cgroup_task_count(css->cgroup);
+}
+
+static u64 current_css_set_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ return (u64)(unsigned long)current->cgroups;
+}
+
+static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ u64 count;
+
+ rcu_read_lock();
+ count = atomic_read(&task_css_set(current)->refcount);
+ rcu_read_unlock();
+ return count;
+}
+
+static int current_css_set_cg_links_read(struct seq_file *seq, void *v)
+{
+ struct cgrp_cset_link *link;
+ struct css_set *cset;
+ char *name_buf;
+
+ name_buf = kmalloc(NAME_MAX + 1, GFP_KERNEL);
+ if (!name_buf)
+ return -ENOMEM;
+
+ spin_lock_irq(&css_set_lock);
+ rcu_read_lock();
+ cset = rcu_dereference(current->cgroups);
+ list_for_each_entry(link, &cset->cgrp_links, cgrp_link) {
+ struct cgroup *c = link->cgrp;
+
+ cgroup_name(c, name_buf, NAME_MAX + 1);
+ seq_printf(seq, "Root %d group %s\n",
+ c->root->hierarchy_id, name_buf);
+ }
+ rcu_read_unlock();
+ spin_unlock_irq(&css_set_lock);
+ kfree(name_buf);
+ return 0;
+}
+
+#define MAX_TASKS_SHOWN_PER_CSS 25
+static int cgroup_css_links_read(struct seq_file *seq, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(seq);
+ struct cgrp_cset_link *link;
+
+ spin_lock_irq(&css_set_lock);
+ list_for_each_entry(link, &css->cgroup->cset_links, cset_link) {
+ struct css_set *cset = link->cset;
+ struct task_struct *task;
+ int count = 0;
+
+ seq_printf(seq, "css_set %p\n", cset);
+
+ list_for_each_entry(task, &cset->tasks, cg_list) {
+ if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+ goto overflow;
+ seq_printf(seq, " task %d\n", task_pid_vnr(task));
+ }
+
+ list_for_each_entry(task, &cset->mg_tasks, cg_list) {
+ if (count++ > MAX_TASKS_SHOWN_PER_CSS)
+ goto overflow;
+ seq_printf(seq, " task %d\n", task_pid_vnr(task));
+ }
+ continue;
+ overflow:
+ seq_puts(seq, " ...\n");
+ }
+ spin_unlock_irq(&css_set_lock);
+ return 0;
+}
+
+static u64 releasable_read(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ return (!cgroup_is_populated(css->cgroup) &&
+ !css_has_online_children(&css->cgroup->self));
+}
+
+static struct cftype debug_files[] = {
+ {
+ .name = "taskcount",
+ .read_u64 = debug_taskcount_read,
+ },
+
+ {
+ .name = "current_css_set",
+ .read_u64 = current_css_set_read,
+ },
+
+ {
+ .name = "current_css_set_refcount",
+ .read_u64 = current_css_set_refcount_read,
+ },
+
+ {
+ .name = "current_css_set_cg_links",
+ .seq_show = current_css_set_cg_links_read,
+ },
+
+ {
+ .name = "cgroup_css_links",
+ .seq_show = cgroup_css_links_read,
+ },
+
+ {
+ .name = "releasable",
+ .read_u64 = releasable_read,
+ },
+
+ { } /* terminate */
+};
+
+struct cgroup_subsys debug_cgrp_subsys = {
+ .css_alloc = debug_css_alloc,
+ .css_free = debug_css_free,
+ .legacy_cftypes = debug_files,
+};
+#endif /* CONFIG_CGROUP_DEBUG */
--- /dev/null
+/*
+ * kernel/cpuset.c
+ *
+ * Processor and Memory placement constraints for sets of tasks.
+ *
+ * Copyright (C) 2003 BULL SA.
+ * Copyright (C) 2004-2007 Silicon Graphics, Inc.
+ * Copyright (C) 2006 Google, Inc
+ *
+ * Portions derived from Patrick Mochel's sysfs code.
+ * sysfs is Copyright (c) 2001-3 Patrick Mochel
+ *
+ * 2003-10-10 Written by Simon Derr.
+ * 2003-10-22 Updates by Stephen Hemminger.
+ * 2004 May-July Rework by Paul Jackson.
+ * 2006 Rework by Paul Menage to use generic cgroups
+ * 2008 Rework of the scheduler domains and CPU hotplug handling
+ * by Max Krasnyansky
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of the Linux
+ * distribution for more details.
+ */
+
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/cpuset.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/mempolicy.h>
+#include <linux/mm.h>
+#include <linux/memory.h>
+#include <linux/export.h>
+#include <linux/mount.h>
+#include <linux/namei.h>
+#include <linux/pagemap.h>
+#include <linux/proc_fs.h>
+#include <linux/rcupdate.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <linux/security.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/stat.h>
+#include <linux/string.h>
+#include <linux/time.h>
+#include <linux/time64.h>
+#include <linux/backing-dev.h>
+#include <linux/sort.h>
+
+#include <linux/uaccess.h>
+#include <linux/atomic.h>
+#include <linux/mutex.h>
+#include <linux/cgroup.h>
+#include <linux/wait.h>
+
+DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
+
+/* See "Frequency meter" comments, below. */
+
+struct fmeter {
+ int cnt; /* unprocessed events count */
+ int val; /* most recent output value */
+ time64_t time; /* clock (secs) when val computed */
+ spinlock_t lock; /* guards read or write of above */
+};
+
+struct cpuset {
+ struct cgroup_subsys_state css;
+
+ unsigned long flags; /* "unsigned long" so bitops work */
+
+ /*
+ * On default hierarchy:
+ *
+ * The user-configured masks can only be changed by writing to
+ * cpuset.cpus and cpuset.mems, and won't be limited by the
+ * parent masks.
+ *
+ * The effective masks is the real masks that apply to the tasks
+ * in the cpuset. They may be changed if the configured masks are
+ * changed or hotplug happens.
+ *
+ * effective_mask == configured_mask & parent's effective_mask,
+ * and if it ends up empty, it will inherit the parent's mask.
+ *
+ *
+ * On legacy hierachy:
+ *
+ * The user-configured masks are always the same with effective masks.
+ */
+
+ /* user-configured CPUs and Memory Nodes allow to tasks */
+ cpumask_var_t cpus_allowed;
+ nodemask_t mems_allowed;
+
+ /* effective CPUs and Memory Nodes allow to tasks */
+ cpumask_var_t effective_cpus;
+ nodemask_t effective_mems;
+
+ /*
+ * This is old Memory Nodes tasks took on.
+ *
+ * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
+ * - A new cpuset's old_mems_allowed is initialized when some
+ * task is moved into it.
+ * - old_mems_allowed is used in cpuset_migrate_mm() when we change
+ * cpuset.mems_allowed and have tasks' nodemask updated, and
+ * then old_mems_allowed is updated to mems_allowed.
+ */
+ nodemask_t old_mems_allowed;
+
+ struct fmeter fmeter; /* memory_pressure filter */
+
+ /*
+ * Tasks are being attached to this cpuset. Used to prevent
+ * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
+ */
+ int attach_in_progress;
+
+ /* partition number for rebuild_sched_domains() */
+ int pn;
+
+ /* for custom sched domain */
+ int relax_domain_level;
+};
+
+static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct cpuset, css) : NULL;
+}
+
+/* Retrieve the cpuset for a task */
+static inline struct cpuset *task_cs(struct task_struct *task)
+{
+ return css_cs(task_css(task, cpuset_cgrp_id));
+}
+
+static inline struct cpuset *parent_cs(struct cpuset *cs)
+{
+ return css_cs(cs->css.parent);
+}
+
+#ifdef CONFIG_NUMA
+static inline bool task_has_mempolicy(struct task_struct *task)
+{
+ return task->mempolicy;
+}
+#else
+static inline bool task_has_mempolicy(struct task_struct *task)
+{
+ return false;
+}
+#endif
+
+
+/* bits in struct cpuset flags field */
+typedef enum {
+ CS_ONLINE,
+ CS_CPU_EXCLUSIVE,
+ CS_MEM_EXCLUSIVE,
+ CS_MEM_HARDWALL,
+ CS_MEMORY_MIGRATE,
+ CS_SCHED_LOAD_BALANCE,
+ CS_SPREAD_PAGE,
+ CS_SPREAD_SLAB,
+} cpuset_flagbits_t;
+
+/* convenient tests for these bits */
+static inline bool is_cpuset_online(const struct cpuset *cs)
+{
+ return test_bit(CS_ONLINE, &cs->flags);
+}
+
+static inline int is_cpu_exclusive(const struct cpuset *cs)
+{
+ return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
+}
+
+static inline int is_mem_exclusive(const struct cpuset *cs)
+{
+ return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
+}
+
+static inline int is_mem_hardwall(const struct cpuset *cs)
+{
+ return test_bit(CS_MEM_HARDWALL, &cs->flags);
+}
+
+static inline int is_sched_load_balance(const struct cpuset *cs)
+{
+ return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+}
+
+static inline int is_memory_migrate(const struct cpuset *cs)
+{
+ return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
+}
+
+static inline int is_spread_page(const struct cpuset *cs)
+{
+ return test_bit(CS_SPREAD_PAGE, &cs->flags);
+}
+
+static inline int is_spread_slab(const struct cpuset *cs)
+{
+ return test_bit(CS_SPREAD_SLAB, &cs->flags);
+}
+
+static struct cpuset top_cpuset = {
+ .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
+ (1 << CS_MEM_EXCLUSIVE)),
+};
+
+/**
+ * cpuset_for_each_child - traverse online children of a cpuset
+ * @child_cs: loop cursor pointing to the current child
+ * @pos_css: used for iteration
+ * @parent_cs: target cpuset to walk children of
+ *
+ * Walk @child_cs through the online children of @parent_cs. Must be used
+ * with RCU read locked.
+ */
+#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
+ css_for_each_child((pos_css), &(parent_cs)->css) \
+ if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
+
+/**
+ * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
+ * @des_cs: loop cursor pointing to the current descendant
+ * @pos_css: used for iteration
+ * @root_cs: target cpuset to walk ancestor of
+ *
+ * Walk @des_cs through the online descendants of @root_cs. Must be used
+ * with RCU read locked. The caller may modify @pos_css by calling
+ * css_rightmost_descendant() to skip subtree. @root_cs is included in the
+ * iteration and the first node to be visited.
+ */
+#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
+ css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
+ if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
+
+/*
+ * There are two global locks guarding cpuset structures - cpuset_mutex and
+ * callback_lock. We also require taking task_lock() when dereferencing a
+ * task's cpuset pointer. See "The task_lock() exception", at the end of this
+ * comment.
+ *
+ * A task must hold both locks to modify cpusets. If a task holds
+ * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
+ * is the only task able to also acquire callback_lock and be able to
+ * modify cpusets. It can perform various checks on the cpuset structure
+ * first, knowing nothing will change. It can also allocate memory while
+ * just holding cpuset_mutex. While it is performing these checks, various
+ * callback routines can briefly acquire callback_lock to query cpusets.
+ * Once it is ready to make the changes, it takes callback_lock, blocking
+ * everyone else.
+ *
+ * Calls to the kernel memory allocator can not be made while holding
+ * callback_lock, as that would risk double tripping on callback_lock
+ * from one of the callbacks into the cpuset code from within
+ * __alloc_pages().
+ *
+ * If a task is only holding callback_lock, then it has read-only
+ * access to cpusets.
+ *
+ * Now, the task_struct fields mems_allowed and mempolicy may be changed
+ * by other task, we use alloc_lock in the task_struct fields to protect
+ * them.
+ *
+ * The cpuset_common_file_read() handlers only hold callback_lock across
+ * small pieces of code, such as when reading out possibly multi-word
+ * cpumasks and nodemasks.
+ *
+ * Accessing a task's cpuset should be done in accordance with the
+ * guidelines for accessing subsystem state in kernel/cgroup.c
+ */
+
+static DEFINE_MUTEX(cpuset_mutex);
+static DEFINE_SPINLOCK(callback_lock);
+
+static struct workqueue_struct *cpuset_migrate_mm_wq;
+
+/*
+ * CPU / memory hotplug is handled asynchronously.
+ */
+static void cpuset_hotplug_workfn(struct work_struct *work);
+static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
+
+static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
+
+/*
+ * This is ugly, but preserves the userspace API for existing cpuset
+ * users. If someone tries to mount the "cpuset" filesystem, we
+ * silently switch it to mount "cgroup" instead
+ */
+static struct dentry *cpuset_mount(struct file_system_type *fs_type,
+ int flags, const char *unused_dev_name, void *data)
+{
+ struct file_system_type *cgroup_fs = get_fs_type("cgroup");
+ struct dentry *ret = ERR_PTR(-ENODEV);
+ if (cgroup_fs) {
+ char mountopts[] =
+ "cpuset,noprefix,"
+ "release_agent=/sbin/cpuset_release_agent";
+ ret = cgroup_fs->mount(cgroup_fs, flags,
+ unused_dev_name, mountopts);
+ put_filesystem(cgroup_fs);
+ }
+ return ret;
+}
+
+static struct file_system_type cpuset_fs_type = {
+ .name = "cpuset",
+ .mount = cpuset_mount,
+};
+
+/*
+ * Return in pmask the portion of a cpusets's cpus_allowed that
+ * are online. If none are online, walk up the cpuset hierarchy
+ * until we find one that does have some online cpus.
+ *
+ * One way or another, we guarantee to return some non-empty subset
+ * of cpu_online_mask.
+ *
+ * Call with callback_lock or cpuset_mutex held.
+ */
+static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
+{
+ while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
+ cs = parent_cs(cs);
+ if (unlikely(!cs)) {
+ /*
+ * The top cpuset doesn't have any online cpu as a
+ * consequence of a race between cpuset_hotplug_work
+ * and cpu hotplug notifier. But we know the top
+ * cpuset's effective_cpus is on its way to to be
+ * identical to cpu_online_mask.
+ */
+ cpumask_copy(pmask, cpu_online_mask);
+ return;
+ }
+ }
+ cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
+}
+
+/*
+ * Return in *pmask the portion of a cpusets's mems_allowed that
+ * are online, with memory. If none are online with memory, walk
+ * up the cpuset hierarchy until we find one that does have some
+ * online mems. The top cpuset always has some mems online.
+ *
+ * One way or another, we guarantee to return some non-empty subset
+ * of node_states[N_MEMORY].
+ *
+ * Call with callback_lock or cpuset_mutex held.
+ */
+static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
+{
+ while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
+ cs = parent_cs(cs);
+ nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
+}
+
+/*
+ * update task's spread flag if cpuset's page/slab spread flag is set
+ *
+ * Call with callback_lock or cpuset_mutex held.
+ */
+static void cpuset_update_task_spread_flag(struct cpuset *cs,
+ struct task_struct *tsk)
+{
+ if (is_spread_page(cs))
+ task_set_spread_page(tsk);
+ else
+ task_clear_spread_page(tsk);
+
+ if (is_spread_slab(cs))
+ task_set_spread_slab(tsk);
+ else
+ task_clear_spread_slab(tsk);
+}
+
+/*
+ * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
+ *
+ * One cpuset is a subset of another if all its allowed CPUs and
+ * Memory Nodes are a subset of the other, and its exclusive flags
+ * are only set if the other's are set. Call holding cpuset_mutex.
+ */
+
+static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
+{
+ return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
+ nodes_subset(p->mems_allowed, q->mems_allowed) &&
+ is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
+ is_mem_exclusive(p) <= is_mem_exclusive(q);
+}
+
+/**
+ * alloc_trial_cpuset - allocate a trial cpuset
+ * @cs: the cpuset that the trial cpuset duplicates
+ */
+static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
+{
+ struct cpuset *trial;
+
+ trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
+ if (!trial)
+ return NULL;
+
+ if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
+ goto free_cs;
+ if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
+ goto free_cpus;
+
+ cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
+ cpumask_copy(trial->effective_cpus, cs->effective_cpus);
+ return trial;
+
+free_cpus:
+ free_cpumask_var(trial->cpus_allowed);
+free_cs:
+ kfree(trial);
+ return NULL;
+}
+
+/**
+ * free_trial_cpuset - free the trial cpuset
+ * @trial: the trial cpuset to be freed
+ */
+static void free_trial_cpuset(struct cpuset *trial)
+{
+ free_cpumask_var(trial->effective_cpus);
+ free_cpumask_var(trial->cpus_allowed);
+ kfree(trial);
+}
+
+/*
+ * validate_change() - Used to validate that any proposed cpuset change
+ * follows the structural rules for cpusets.
+ *
+ * If we replaced the flag and mask values of the current cpuset
+ * (cur) with those values in the trial cpuset (trial), would
+ * our various subset and exclusive rules still be valid? Presumes
+ * cpuset_mutex held.
+ *
+ * 'cur' is the address of an actual, in-use cpuset. Operations
+ * such as list traversal that depend on the actual address of the
+ * cpuset in the list must use cur below, not trial.
+ *
+ * 'trial' is the address of bulk structure copy of cur, with
+ * perhaps one or more of the fields cpus_allowed, mems_allowed,
+ * or flags changed to new, trial values.
+ *
+ * Return 0 if valid, -errno if not.
+ */
+
+static int validate_change(struct cpuset *cur, struct cpuset *trial)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *c, *par;
+ int ret;
+
+ rcu_read_lock();
+
+ /* Each of our child cpusets must be a subset of us */
+ ret = -EBUSY;
+ cpuset_for_each_child(c, css, cur)
+ if (!is_cpuset_subset(c, trial))
+ goto out;
+
+ /* Remaining checks don't apply to root cpuset */
+ ret = 0;
+ if (cur == &top_cpuset)
+ goto out;
+
+ par = parent_cs(cur);
+
+ /* On legacy hiearchy, we must be a subset of our parent cpuset. */
+ ret = -EACCES;
+ if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ !is_cpuset_subset(trial, par))
+ goto out;
+
+ /*
+ * If either I or some sibling (!= me) is exclusive, we can't
+ * overlap
+ */
+ ret = -EINVAL;
+ cpuset_for_each_child(c, css, par) {
+ if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
+ c != cur &&
+ cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
+ goto out;
+ if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
+ c != cur &&
+ nodes_intersects(trial->mems_allowed, c->mems_allowed))
+ goto out;
+ }
+
+ /*
+ * Cpusets with tasks - existing or newly being attached - can't
+ * be changed to have empty cpus_allowed or mems_allowed.
+ */
+ ret = -ENOSPC;
+ if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
+ if (!cpumask_empty(cur->cpus_allowed) &&
+ cpumask_empty(trial->cpus_allowed))
+ goto out;
+ if (!nodes_empty(cur->mems_allowed) &&
+ nodes_empty(trial->mems_allowed))
+ goto out;
+ }
+
+ /*
+ * We can't shrink if we won't have enough room for SCHED_DEADLINE
+ * tasks.
+ */
+ ret = -EBUSY;
+ if (is_cpu_exclusive(cur) &&
+ !cpuset_cpumask_can_shrink(cur->cpus_allowed,
+ trial->cpus_allowed))
+ goto out;
+
+ ret = 0;
+out:
+ rcu_read_unlock();
+ return ret;
+}
+
+#ifdef CONFIG_SMP
+/*
+ * Helper routine for generate_sched_domains().
+ * Do cpusets a, b have overlapping effective cpus_allowed masks?
+ */
+static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
+{
+ return cpumask_intersects(a->effective_cpus, b->effective_cpus);
+}
+
+static void
+update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
+{
+ if (dattr->relax_domain_level < c->relax_domain_level)
+ dattr->relax_domain_level = c->relax_domain_level;
+ return;
+}
+
+static void update_domain_attr_tree(struct sched_domain_attr *dattr,
+ struct cpuset *root_cs)
+{
+ struct cpuset *cp;
+ struct cgroup_subsys_state *pos_css;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
+ /* skip the whole subtree if @cp doesn't have any CPU */
+ if (cpumask_empty(cp->cpus_allowed)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ if (is_sched_load_balance(cp))
+ update_domain_attr(dattr, cp);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * generate_sched_domains()
+ *
+ * This function builds a partial partition of the systems CPUs
+ * A 'partial partition' is a set of non-overlapping subsets whose
+ * union is a subset of that set.
+ * The output of this function needs to be passed to kernel/sched/core.c
+ * partition_sched_domains() routine, which will rebuild the scheduler's
+ * load balancing domains (sched domains) as specified by that partial
+ * partition.
+ *
+ * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
+ * for a background explanation of this.
+ *
+ * Does not return errors, on the theory that the callers of this
+ * routine would rather not worry about failures to rebuild sched
+ * domains when operating in the severe memory shortage situations
+ * that could cause allocation failures below.
+ *
+ * Must be called with cpuset_mutex held.
+ *
+ * The three key local variables below are:
+ * q - a linked-list queue of cpuset pointers, used to implement a
+ * top-down scan of all cpusets. This scan loads a pointer
+ * to each cpuset marked is_sched_load_balance into the
+ * array 'csa'. For our purposes, rebuilding the schedulers
+ * sched domains, we can ignore !is_sched_load_balance cpusets.
+ * csa - (for CpuSet Array) Array of pointers to all the cpusets
+ * that need to be load balanced, for convenient iterative
+ * access by the subsequent code that finds the best partition,
+ * i.e the set of domains (subsets) of CPUs such that the
+ * cpus_allowed of every cpuset marked is_sched_load_balance
+ * is a subset of one of these domains, while there are as
+ * many such domains as possible, each as small as possible.
+ * doms - Conversion of 'csa' to an array of cpumasks, for passing to
+ * the kernel/sched/core.c routine partition_sched_domains() in a
+ * convenient format, that can be easily compared to the prior
+ * value to determine what partition elements (sched domains)
+ * were changed (added or removed.)
+ *
+ * Finding the best partition (set of domains):
+ * The triple nested loops below over i, j, k scan over the
+ * load balanced cpusets (using the array of cpuset pointers in
+ * csa[]) looking for pairs of cpusets that have overlapping
+ * cpus_allowed, but which don't have the same 'pn' partition
+ * number and gives them in the same partition number. It keeps
+ * looping on the 'restart' label until it can no longer find
+ * any such pairs.
+ *
+ * The union of the cpus_allowed masks from the set of
+ * all cpusets having the same 'pn' value then form the one
+ * element of the partition (one sched domain) to be passed to
+ * partition_sched_domains().
+ */
+static int generate_sched_domains(cpumask_var_t **domains,
+ struct sched_domain_attr **attributes)
+{
+ struct cpuset *cp; /* scans q */
+ struct cpuset **csa; /* array of all cpuset ptrs */
+ int csn; /* how many cpuset ptrs in csa so far */
+ int i, j, k; /* indices for partition finding loops */
+ cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
+ cpumask_var_t non_isolated_cpus; /* load balanced CPUs */
+ struct sched_domain_attr *dattr; /* attributes for custom domains */
+ int ndoms = 0; /* number of sched domains in result */
+ int nslot; /* next empty doms[] struct cpumask slot */
+ struct cgroup_subsys_state *pos_css;
+
+ doms = NULL;
+ dattr = NULL;
+ csa = NULL;
+
+ if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
+ goto done;
+ cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
+
+ /* Special case for the 99% of systems with one, full, sched domain */
+ if (is_sched_load_balance(&top_cpuset)) {
+ ndoms = 1;
+ doms = alloc_sched_domains(ndoms);
+ if (!doms)
+ goto done;
+
+ dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
+ if (dattr) {
+ *dattr = SD_ATTR_INIT;
+ update_domain_attr_tree(dattr, &top_cpuset);
+ }
+ cpumask_and(doms[0], top_cpuset.effective_cpus,
+ non_isolated_cpus);
+
+ goto done;
+ }
+
+ csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
+ if (!csa)
+ goto done;
+ csn = 0;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
+ if (cp == &top_cpuset)
+ continue;
+ /*
+ * Continue traversing beyond @cp iff @cp has some CPUs and
+ * isn't load balancing. The former is obvious. The
+ * latter: All child cpusets contain a subset of the
+ * parent's cpus, so just skip them, and then we call
+ * update_domain_attr_tree() to calc relax_domain_level of
+ * the corresponding sched domain.
+ */
+ if (!cpumask_empty(cp->cpus_allowed) &&
+ !(is_sched_load_balance(cp) &&
+ cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
+ continue;
+
+ if (is_sched_load_balance(cp))
+ csa[csn++] = cp;
+
+ /* skip @cp's subtree */
+ pos_css = css_rightmost_descendant(pos_css);
+ }
+ rcu_read_unlock();
+
+ for (i = 0; i < csn; i++)
+ csa[i]->pn = i;
+ ndoms = csn;
+
+restart:
+ /* Find the best partition (set of sched domains) */
+ for (i = 0; i < csn; i++) {
+ struct cpuset *a = csa[i];
+ int apn = a->pn;
+
+ for (j = 0; j < csn; j++) {
+ struct cpuset *b = csa[j];
+ int bpn = b->pn;
+
+ if (apn != bpn && cpusets_overlap(a, b)) {
+ for (k = 0; k < csn; k++) {
+ struct cpuset *c = csa[k];
+
+ if (c->pn == bpn)
+ c->pn = apn;
+ }
+ ndoms--; /* one less element */
+ goto restart;
+ }
+ }
+ }
+
+ /*
+ * Now we know how many domains to create.
+ * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
+ */
+ doms = alloc_sched_domains(ndoms);
+ if (!doms)
+ goto done;
+
+ /*
+ * The rest of the code, including the scheduler, can deal with
+ * dattr==NULL case. No need to abort if alloc fails.
+ */
+ dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
+
+ for (nslot = 0, i = 0; i < csn; i++) {
+ struct cpuset *a = csa[i];
+ struct cpumask *dp;
+ int apn = a->pn;
+
+ if (apn < 0) {
+ /* Skip completed partitions */
+ continue;
+ }
+
+ dp = doms[nslot];
+
+ if (nslot == ndoms) {
+ static int warnings = 10;
+ if (warnings) {
+ pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
+ nslot, ndoms, csn, i, apn);
+ warnings--;
+ }
+ continue;
+ }
+
+ cpumask_clear(dp);
+ if (dattr)
+ *(dattr + nslot) = SD_ATTR_INIT;
+ for (j = i; j < csn; j++) {
+ struct cpuset *b = csa[j];
+
+ if (apn == b->pn) {
+ cpumask_or(dp, dp, b->effective_cpus);
+ cpumask_and(dp, dp, non_isolated_cpus);
+ if (dattr)
+ update_domain_attr_tree(dattr + nslot, b);
+
+ /* Done with this partition */
+ b->pn = -1;
+ }
+ }
+ nslot++;
+ }
+ BUG_ON(nslot != ndoms);
+
+done:
+ free_cpumask_var(non_isolated_cpus);
+ kfree(csa);
+
+ /*
+ * Fallback to the default domain if kmalloc() failed.
+ * See comments in partition_sched_domains().
+ */
+ if (doms == NULL)
+ ndoms = 1;
+
+ *domains = doms;
+ *attributes = dattr;
+ return ndoms;
+}
+
+/*
+ * Rebuild scheduler domains.
+ *
+ * If the flag 'sched_load_balance' of any cpuset with non-empty
+ * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
+ * which has that flag enabled, or if any cpuset with a non-empty
+ * 'cpus' is removed, then call this routine to rebuild the
+ * scheduler's dynamic sched domains.
+ *
+ * Call with cpuset_mutex held. Takes get_online_cpus().
+ */
+static void rebuild_sched_domains_locked(void)
+{
+ struct sched_domain_attr *attr;
+ cpumask_var_t *doms;
+ int ndoms;
+
+ lockdep_assert_held(&cpuset_mutex);
+ get_online_cpus();
+
+ /*
+ * We have raced with CPU hotplug. Don't do anything to avoid
+ * passing doms with offlined cpu to partition_sched_domains().
+ * Anyways, hotplug work item will rebuild sched domains.
+ */
+ if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
+ goto out;
+
+ /* Generate domain masks and attrs */
+ ndoms = generate_sched_domains(&doms, &attr);
+
+ /* Have scheduler rebuild the domains */
+ partition_sched_domains(ndoms, doms, attr);
+out:
+ put_online_cpus();
+}
+#else /* !CONFIG_SMP */
+static void rebuild_sched_domains_locked(void)
+{
+}
+#endif /* CONFIG_SMP */
+
+void rebuild_sched_domains(void)
+{
+ mutex_lock(&cpuset_mutex);
+ rebuild_sched_domains_locked();
+ mutex_unlock(&cpuset_mutex);
+}
+
+/**
+ * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
+ *
+ * Iterate through each task of @cs updating its cpus_allowed to the
+ * effective cpuset's. As this function is called with cpuset_mutex held,
+ * cpuset membership stays stable.
+ */
+static void update_tasks_cpumask(struct cpuset *cs)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&cs->css, &it);
+ while ((task = css_task_iter_next(&it)))
+ set_cpus_allowed_ptr(task, cs->effective_cpus);
+ css_task_iter_end(&it);
+}
+
+/*
+ * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
+ * @cs: the cpuset to consider
+ * @new_cpus: temp variable for calculating new effective_cpus
+ *
+ * When congifured cpumask is changed, the effective cpumasks of this cpuset
+ * and all its descendants need to be updated.
+ *
+ * On legacy hierachy, effective_cpus will be the same with cpu_allowed.
+ *
+ * Called with cpuset_mutex held
+ */
+static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
+{
+ struct cpuset *cp;
+ struct cgroup_subsys_state *pos_css;
+ bool need_rebuild_sched_domains = false;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, cs) {
+ struct cpuset *parent = parent_cs(cp);
+
+ cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
+
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some CPUs.
+ */
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ cpumask_empty(new_cpus))
+ cpumask_copy(new_cpus, parent->effective_cpus);
+
+ /* Skip the whole subtree if the cpumask remains the same. */
+ if (cpumask_equal(new_cpus, cp->effective_cpus)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ if (!css_tryget_online(&cp->css))
+ continue;
+ rcu_read_unlock();
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cp->effective_cpus, new_cpus);
+ spin_unlock_irq(&callback_lock);
+
+ WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
+
+ update_tasks_cpumask(cp);
+
+ /*
+ * If the effective cpumask of any non-empty cpuset is changed,
+ * we need to rebuild sched domains.
+ */
+ if (!cpumask_empty(cp->cpus_allowed) &&
+ is_sched_load_balance(cp))
+ need_rebuild_sched_domains = true;
+
+ rcu_read_lock();
+ css_put(&cp->css);
+ }
+ rcu_read_unlock();
+
+ if (need_rebuild_sched_domains)
+ rebuild_sched_domains_locked();
+}
+
+/**
+ * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
+ * @cs: the cpuset to consider
+ * @trialcs: trial cpuset
+ * @buf: buffer of cpu numbers written to this cpuset
+ */
+static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
+ const char *buf)
+{
+ int retval;
+
+ /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
+ if (cs == &top_cpuset)
+ return -EACCES;
+
+ /*
+ * An empty cpus_allowed is ok only if the cpuset has no tasks.
+ * Since cpulist_parse() fails on an empty mask, we special case
+ * that parsing. The validate_change() call ensures that cpusets
+ * with tasks have cpus.
+ */
+ if (!*buf) {
+ cpumask_clear(trialcs->cpus_allowed);
+ } else {
+ retval = cpulist_parse(buf, trialcs->cpus_allowed);
+ if (retval < 0)
+ return retval;
+
+ if (!cpumask_subset(trialcs->cpus_allowed,
+ top_cpuset.cpus_allowed))
+ return -EINVAL;
+ }
+
+ /* Nothing to do if the cpus didn't change */
+ if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
+ return 0;
+
+ retval = validate_change(cs, trialcs);
+ if (retval < 0)
+ return retval;
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
+ spin_unlock_irq(&callback_lock);
+
+ /* use trialcs->cpus_allowed as a temp variable */
+ update_cpumasks_hier(cs, trialcs->cpus_allowed);
+ return 0;
+}
+
+/*
+ * Migrate memory region from one set of nodes to another. This is
+ * performed asynchronously as it can be called from process migration path
+ * holding locks involved in process management. All mm migrations are
+ * performed in the queued order and can be waited for by flushing
+ * cpuset_migrate_mm_wq.
+ */
+
+struct cpuset_migrate_mm_work {
+ struct work_struct work;
+ struct mm_struct *mm;
+ nodemask_t from;
+ nodemask_t to;
+};
+
+static void cpuset_migrate_mm_workfn(struct work_struct *work)
+{
+ struct cpuset_migrate_mm_work *mwork =
+ container_of(work, struct cpuset_migrate_mm_work, work);
+
+ /* on a wq worker, no need to worry about %current's mems_allowed */
+ do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
+ mmput(mwork->mm);
+ kfree(mwork);
+}
+
+static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
+ const nodemask_t *to)
+{
+ struct cpuset_migrate_mm_work *mwork;
+
+ mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
+ if (mwork) {
+ mwork->mm = mm;
+ mwork->from = *from;
+ mwork->to = *to;
+ INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
+ queue_work(cpuset_migrate_mm_wq, &mwork->work);
+ } else {
+ mmput(mm);
+ }
+}
+
+static void cpuset_post_attach(void)
+{
+ flush_workqueue(cpuset_migrate_mm_wq);
+}
+
+/*
+ * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
+ * @tsk: the task to change
+ * @newmems: new nodes that the task will be set
+ *
+ * In order to avoid seeing no nodes if the old and new nodes are disjoint,
+ * we structure updates as setting all new allowed nodes, then clearing newly
+ * disallowed ones.
+ */
+static void cpuset_change_task_nodemask(struct task_struct *tsk,
+ nodemask_t *newmems)
+{
+ bool need_loop;
+
+ task_lock(tsk);
+ /*
+ * Determine if a loop is necessary if another thread is doing
+ * read_mems_allowed_begin(). If at least one node remains unchanged and
+ * tsk does not have a mempolicy, then an empty nodemask will not be
+ * possible when mems_allowed is larger than a word.
+ */
+ need_loop = task_has_mempolicy(tsk) ||
+ !nodes_intersects(*newmems, tsk->mems_allowed);
+
+ if (need_loop) {
+ local_irq_disable();
+ write_seqcount_begin(&tsk->mems_allowed_seq);
+ }
+
+ nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
+ mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
+
+ mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
+ tsk->mems_allowed = *newmems;
+
+ if (need_loop) {
+ write_seqcount_end(&tsk->mems_allowed_seq);
+ local_irq_enable();
+ }
+
+ task_unlock(tsk);
+}
+
+static void *cpuset_being_rebound;
+
+/**
+ * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
+ * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
+ *
+ * Iterate through each task of @cs updating its mems_allowed to the
+ * effective cpuset's. As this function is called with cpuset_mutex held,
+ * cpuset membership stays stable.
+ */
+static void update_tasks_nodemask(struct cpuset *cs)
+{
+ static nodemask_t newmems; /* protected by cpuset_mutex */
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
+
+ guarantee_online_mems(cs, &newmems);
+
+ /*
+ * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
+ * take while holding tasklist_lock. Forks can happen - the
+ * mpol_dup() cpuset_being_rebound check will catch such forks,
+ * and rebind their vma mempolicies too. Because we still hold
+ * the global cpuset_mutex, we know that no other rebind effort
+ * will be contending for the global variable cpuset_being_rebound.
+ * It's ok if we rebind the same mm twice; mpol_rebind_mm()
+ * is idempotent. Also migrate pages in each mm to new nodes.
+ */
+ css_task_iter_start(&cs->css, &it);
+ while ((task = css_task_iter_next(&it))) {
+ struct mm_struct *mm;
+ bool migrate;
+
+ cpuset_change_task_nodemask(task, &newmems);
+
+ mm = get_task_mm(task);
+ if (!mm)
+ continue;
+
+ migrate = is_memory_migrate(cs);
+
+ mpol_rebind_mm(mm, &cs->mems_allowed);
+ if (migrate)
+ cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
+ else
+ mmput(mm);
+ }
+ css_task_iter_end(&it);
+
+ /*
+ * All the tasks' nodemasks have been updated, update
+ * cs->old_mems_allowed.
+ */
+ cs->old_mems_allowed = newmems;
+
+ /* We're done rebinding vmas to this cpuset's new mems_allowed. */
+ cpuset_being_rebound = NULL;
+}
+
+/*
+ * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
+ * @cs: the cpuset to consider
+ * @new_mems: a temp variable for calculating new effective_mems
+ *
+ * When configured nodemask is changed, the effective nodemasks of this cpuset
+ * and all its descendants need to be updated.
+ *
+ * On legacy hiearchy, effective_mems will be the same with mems_allowed.
+ *
+ * Called with cpuset_mutex held
+ */
+static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
+{
+ struct cpuset *cp;
+ struct cgroup_subsys_state *pos_css;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cp, pos_css, cs) {
+ struct cpuset *parent = parent_cs(cp);
+
+ nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
+
+ /*
+ * If it becomes empty, inherit the effective mask of the
+ * parent, which is guaranteed to have some MEMs.
+ */
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ nodes_empty(*new_mems))
+ *new_mems = parent->effective_mems;
+
+ /* Skip the whole subtree if the nodemask remains the same. */
+ if (nodes_equal(*new_mems, cp->effective_mems)) {
+ pos_css = css_rightmost_descendant(pos_css);
+ continue;
+ }
+
+ if (!css_tryget_online(&cp->css))
+ continue;
+ rcu_read_unlock();
+
+ spin_lock_irq(&callback_lock);
+ cp->effective_mems = *new_mems;
+ spin_unlock_irq(&callback_lock);
+
+ WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ !nodes_equal(cp->mems_allowed, cp->effective_mems));
+
+ update_tasks_nodemask(cp);
+
+ rcu_read_lock();
+ css_put(&cp->css);
+ }
+ rcu_read_unlock();
+}
+
+/*
+ * Handle user request to change the 'mems' memory placement
+ * of a cpuset. Needs to validate the request, update the
+ * cpusets mems_allowed, and for each task in the cpuset,
+ * update mems_allowed and rebind task's mempolicy and any vma
+ * mempolicies and if the cpuset is marked 'memory_migrate',
+ * migrate the tasks pages to the new memory.
+ *
+ * Call with cpuset_mutex held. May take callback_lock during call.
+ * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
+ * lock each such tasks mm->mmap_sem, scan its vma's and rebind
+ * their mempolicies to the cpusets new mems_allowed.
+ */
+static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
+ const char *buf)
+{
+ int retval;
+
+ /*
+ * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
+ * it's read-only
+ */
+ if (cs == &top_cpuset) {
+ retval = -EACCES;
+ goto done;
+ }
+
+ /*
+ * An empty mems_allowed is ok iff there are no tasks in the cpuset.
+ * Since nodelist_parse() fails on an empty mask, we special case
+ * that parsing. The validate_change() call ensures that cpusets
+ * with tasks have memory.
+ */
+ if (!*buf) {
+ nodes_clear(trialcs->mems_allowed);
+ } else {
+ retval = nodelist_parse(buf, trialcs->mems_allowed);
+ if (retval < 0)
+ goto done;
+
+ if (!nodes_subset(trialcs->mems_allowed,
+ top_cpuset.mems_allowed)) {
+ retval = -EINVAL;
+ goto done;
+ }
+ }
+
+ if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
+ retval = 0; /* Too easy - nothing to do */
+ goto done;
+ }
+ retval = validate_change(cs, trialcs);
+ if (retval < 0)
+ goto done;
+
+ spin_lock_irq(&callback_lock);
+ cs->mems_allowed = trialcs->mems_allowed;
+ spin_unlock_irq(&callback_lock);
+
+ /* use trialcs->mems_allowed as a temp variable */
+ update_nodemasks_hier(cs, &trialcs->mems_allowed);
+done:
+ return retval;
+}
+
+int current_cpuset_is_being_rebound(void)
+{
+ int ret;
+
+ rcu_read_lock();
+ ret = task_cs(current) == cpuset_being_rebound;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static int update_relax_domain_level(struct cpuset *cs, s64 val)
+{
+#ifdef CONFIG_SMP
+ if (val < -1 || val >= sched_domain_level_max)
+ return -EINVAL;
+#endif
+
+ if (val != cs->relax_domain_level) {
+ cs->relax_domain_level = val;
+ if (!cpumask_empty(cs->cpus_allowed) &&
+ is_sched_load_balance(cs))
+ rebuild_sched_domains_locked();
+ }
+
+ return 0;
+}
+
+/**
+ * update_tasks_flags - update the spread flags of tasks in the cpuset.
+ * @cs: the cpuset in which each task's spread flags needs to be changed
+ *
+ * Iterate through each task of @cs updating its spread flags. As this
+ * function is called with cpuset_mutex held, cpuset membership stays
+ * stable.
+ */
+static void update_tasks_flags(struct cpuset *cs)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&cs->css, &it);
+ while ((task = css_task_iter_next(&it)))
+ cpuset_update_task_spread_flag(cs, task);
+ css_task_iter_end(&it);
+}
+
+/*
+ * update_flag - read a 0 or a 1 in a file and update associated flag
+ * bit: the bit to update (see cpuset_flagbits_t)
+ * cs: the cpuset to update
+ * turning_on: whether the flag is being set or cleared
+ *
+ * Call with cpuset_mutex held.
+ */
+
+static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
+ int turning_on)
+{
+ struct cpuset *trialcs;
+ int balance_flag_changed;
+ int spread_flag_changed;
+ int err;
+
+ trialcs = alloc_trial_cpuset(cs);
+ if (!trialcs)
+ return -ENOMEM;
+
+ if (turning_on)
+ set_bit(bit, &trialcs->flags);
+ else
+ clear_bit(bit, &trialcs->flags);
+
+ err = validate_change(cs, trialcs);
+ if (err < 0)
+ goto out;
+
+ balance_flag_changed = (is_sched_load_balance(cs) !=
+ is_sched_load_balance(trialcs));
+
+ spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
+ || (is_spread_page(cs) != is_spread_page(trialcs)));
+
+ spin_lock_irq(&callback_lock);
+ cs->flags = trialcs->flags;
+ spin_unlock_irq(&callback_lock);
+
+ if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
+ rebuild_sched_domains_locked();
+
+ if (spread_flag_changed)
+ update_tasks_flags(cs);
+out:
+ free_trial_cpuset(trialcs);
+ return err;
+}
+
+/*
+ * Frequency meter - How fast is some event occurring?
+ *
+ * These routines manage a digitally filtered, constant time based,
+ * event frequency meter. There are four routines:
+ * fmeter_init() - initialize a frequency meter.
+ * fmeter_markevent() - called each time the event happens.
+ * fmeter_getrate() - returns the recent rate of such events.
+ * fmeter_update() - internal routine used to update fmeter.
+ *
+ * A common data structure is passed to each of these routines,
+ * which is used to keep track of the state required to manage the
+ * frequency meter and its digital filter.
+ *
+ * The filter works on the number of events marked per unit time.
+ * The filter is single-pole low-pass recursive (IIR). The time unit
+ * is 1 second. Arithmetic is done using 32-bit integers scaled to
+ * simulate 3 decimal digits of precision (multiplied by 1000).
+ *
+ * With an FM_COEF of 933, and a time base of 1 second, the filter
+ * has a half-life of 10 seconds, meaning that if the events quit
+ * happening, then the rate returned from the fmeter_getrate()
+ * will be cut in half each 10 seconds, until it converges to zero.
+ *
+ * It is not worth doing a real infinitely recursive filter. If more
+ * than FM_MAXTICKS ticks have elapsed since the last filter event,
+ * just compute FM_MAXTICKS ticks worth, by which point the level
+ * will be stable.
+ *
+ * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
+ * arithmetic overflow in the fmeter_update() routine.
+ *
+ * Given the simple 32 bit integer arithmetic used, this meter works
+ * best for reporting rates between one per millisecond (msec) and
+ * one per 32 (approx) seconds. At constant rates faster than one
+ * per msec it maxes out at values just under 1,000,000. At constant
+ * rates between one per msec, and one per second it will stabilize
+ * to a value N*1000, where N is the rate of events per second.
+ * At constant rates between one per second and one per 32 seconds,
+ * it will be choppy, moving up on the seconds that have an event,
+ * and then decaying until the next event. At rates slower than
+ * about one in 32 seconds, it decays all the way back to zero between
+ * each event.
+ */
+
+#define FM_COEF 933 /* coefficient for half-life of 10 secs */
+#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
+#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
+#define FM_SCALE 1000 /* faux fixed point scale */
+
+/* Initialize a frequency meter */
+static void fmeter_init(struct fmeter *fmp)
+{
+ fmp->cnt = 0;
+ fmp->val = 0;
+ fmp->time = 0;
+ spin_lock_init(&fmp->lock);
+}
+
+/* Internal meter update - process cnt events and update value */
+static void fmeter_update(struct fmeter *fmp)
+{
+ time64_t now;
+ u32 ticks;
+
+ now = ktime_get_seconds();
+ ticks = now - fmp->time;
+
+ if (ticks == 0)
+ return;
+
+ ticks = min(FM_MAXTICKS, ticks);
+ while (ticks-- > 0)
+ fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
+ fmp->time = now;
+
+ fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
+ fmp->cnt = 0;
+}
+
+/* Process any previous ticks, then bump cnt by one (times scale). */
+static void fmeter_markevent(struct fmeter *fmp)
+{
+ spin_lock(&fmp->lock);
+ fmeter_update(fmp);
+ fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
+ spin_unlock(&fmp->lock);
+}
+
+/* Process any previous ticks, then return current value. */
+static int fmeter_getrate(struct fmeter *fmp)
+{
+ int val;
+
+ spin_lock(&fmp->lock);
+ fmeter_update(fmp);
+ val = fmp->val;
+ spin_unlock(&fmp->lock);
+ return val;
+}
+
+static struct cpuset *cpuset_attach_old_cs;
+
+/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
+static int cpuset_can_attach(struct cgroup_taskset *tset)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *cs;
+ struct task_struct *task;
+ int ret;
+
+ /* used later by cpuset_attach() */
+ cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
+ cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+
+ /* allow moving tasks into an empty cpuset if on default hierarchy */
+ ret = -ENOSPC;
+ if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
+ (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
+ goto out_unlock;
+
+ cgroup_taskset_for_each(task, css, tset) {
+ ret = task_can_attach(task, cs->cpus_allowed);
+ if (ret)
+ goto out_unlock;
+ ret = security_task_setscheduler(task);
+ if (ret)
+ goto out_unlock;
+ }
+
+ /*
+ * Mark attach is in progress. This makes validate_change() fail
+ * changes which zero cpus/mems_allowed.
+ */
+ cs->attach_in_progress++;
+ ret = 0;
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ return ret;
+}
+
+static void cpuset_cancel_attach(struct cgroup_taskset *tset)
+{
+ struct cgroup_subsys_state *css;
+ struct cpuset *cs;
+
+ cgroup_taskset_first(tset, &css);
+ cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+ css_cs(css)->attach_in_progress--;
+ mutex_unlock(&cpuset_mutex);
+}
+
+/*
+ * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
+ * but we can't allocate it dynamically there. Define it global and
+ * allocate from cpuset_init().
+ */
+static cpumask_var_t cpus_attach;
+
+static void cpuset_attach(struct cgroup_taskset *tset)
+{
+ /* static buf protected by cpuset_mutex */
+ static nodemask_t cpuset_attach_nodemask_to;
+ struct task_struct *task;
+ struct task_struct *leader;
+ struct cgroup_subsys_state *css;
+ struct cpuset *cs;
+ struct cpuset *oldcs = cpuset_attach_old_cs;
+
+ cgroup_taskset_first(tset, &css);
+ cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+
+ /* prepare for attach */
+ if (cs == &top_cpuset)
+ cpumask_copy(cpus_attach, cpu_possible_mask);
+ else
+ guarantee_online_cpus(cs, cpus_attach);
+
+ guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
+
+ cgroup_taskset_for_each(task, css, tset) {
+ /*
+ * can_attach beforehand should guarantee that this doesn't
+ * fail. TODO: have a better way to handle failure here
+ */
+ WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
+
+ cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
+ cpuset_update_task_spread_flag(cs, task);
+ }
+
+ /*
+ * Change mm for all threadgroup leaders. This is expensive and may
+ * sleep and should be moved outside migration path proper.
+ */
+ cpuset_attach_nodemask_to = cs->effective_mems;
+ cgroup_taskset_for_each_leader(leader, css, tset) {
+ struct mm_struct *mm = get_task_mm(leader);
+
+ if (mm) {
+ mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
+
+ /*
+ * old_mems_allowed is the same with mems_allowed
+ * here, except if this task is being moved
+ * automatically due to hotplug. In that case
+ * @mems_allowed has been updated and is empty, so
+ * @old_mems_allowed is the right nodesets that we
+ * migrate mm from.
+ */
+ if (is_memory_migrate(cs))
+ cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
+ &cpuset_attach_nodemask_to);
+ else
+ mmput(mm);
+ }
+ }
+
+ cs->old_mems_allowed = cpuset_attach_nodemask_to;
+
+ cs->attach_in_progress--;
+ if (!cs->attach_in_progress)
+ wake_up(&cpuset_attach_wq);
+
+ mutex_unlock(&cpuset_mutex);
+}
+
+/* The various types of files and directories in a cpuset file system */
+
+typedef enum {
+ FILE_MEMORY_MIGRATE,
+ FILE_CPULIST,
+ FILE_MEMLIST,
+ FILE_EFFECTIVE_CPULIST,
+ FILE_EFFECTIVE_MEMLIST,
+ FILE_CPU_EXCLUSIVE,
+ FILE_MEM_EXCLUSIVE,
+ FILE_MEM_HARDWALL,
+ FILE_SCHED_LOAD_BALANCE,
+ FILE_SCHED_RELAX_DOMAIN_LEVEL,
+ FILE_MEMORY_PRESSURE_ENABLED,
+ FILE_MEMORY_PRESSURE,
+ FILE_SPREAD_PAGE,
+ FILE_SPREAD_SLAB,
+} cpuset_filetype_t;
+
+static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
+ u64 val)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ int retval = 0;
+
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs)) {
+ retval = -ENODEV;
+ goto out_unlock;
+ }
+
+ switch (type) {
+ case FILE_CPU_EXCLUSIVE:
+ retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
+ break;
+ case FILE_MEM_EXCLUSIVE:
+ retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
+ break;
+ case FILE_MEM_HARDWALL:
+ retval = update_flag(CS_MEM_HARDWALL, cs, val);
+ break;
+ case FILE_SCHED_LOAD_BALANCE:
+ retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
+ break;
+ case FILE_MEMORY_MIGRATE:
+ retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
+ break;
+ case FILE_MEMORY_PRESSURE_ENABLED:
+ cpuset_memory_pressure_enabled = !!val;
+ break;
+ case FILE_SPREAD_PAGE:
+ retval = update_flag(CS_SPREAD_PAGE, cs, val);
+ break;
+ case FILE_SPREAD_SLAB:
+ retval = update_flag(CS_SPREAD_SLAB, cs, val);
+ break;
+ default:
+ retval = -EINVAL;
+ break;
+ }
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ return retval;
+}
+
+static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
+ s64 val)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ int retval = -ENODEV;
+
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs))
+ goto out_unlock;
+
+ switch (type) {
+ case FILE_SCHED_RELAX_DOMAIN_LEVEL:
+ retval = update_relax_domain_level(cs, val);
+ break;
+ default:
+ retval = -EINVAL;
+ break;
+ }
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ return retval;
+}
+
+/*
+ * Common handling for a write to a "cpus" or "mems" file.
+ */
+static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ struct cpuset *cs = css_cs(of_css(of));
+ struct cpuset *trialcs;
+ int retval = -ENODEV;
+
+ buf = strstrip(buf);
+
+ /*
+ * CPU or memory hotunplug may leave @cs w/o any execution
+ * resources, in which case the hotplug code asynchronously updates
+ * configuration and transfers all tasks to the nearest ancestor
+ * which can execute.
+ *
+ * As writes to "cpus" or "mems" may restore @cs's execution
+ * resources, wait for the previously scheduled operations before
+ * proceeding, so that we don't end up keep removing tasks added
+ * after execution capability is restored.
+ *
+ * cpuset_hotplug_work calls back into cgroup core via
+ * cgroup_transfer_tasks() and waiting for it from a cgroupfs
+ * operation like this one can lead to a deadlock through kernfs
+ * active_ref protection. Let's break the protection. Losing the
+ * protection is okay as we check whether @cs is online after
+ * grabbing cpuset_mutex anyway. This only happens on the legacy
+ * hierarchies.
+ */
+ css_get(&cs->css);
+ kernfs_break_active_protection(of->kn);
+ flush_work(&cpuset_hotplug_work);
+
+ mutex_lock(&cpuset_mutex);
+ if (!is_cpuset_online(cs))
+ goto out_unlock;
+
+ trialcs = alloc_trial_cpuset(cs);
+ if (!trialcs) {
+ retval = -ENOMEM;
+ goto out_unlock;
+ }
+
+ switch (of_cft(of)->private) {
+ case FILE_CPULIST:
+ retval = update_cpumask(cs, trialcs, buf);
+ break;
+ case FILE_MEMLIST:
+ retval = update_nodemask(cs, trialcs, buf);
+ break;
+ default:
+ retval = -EINVAL;
+ break;
+ }
+
+ free_trial_cpuset(trialcs);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ kernfs_unbreak_active_protection(of->kn);
+ css_put(&cs->css);
+ flush_workqueue(cpuset_migrate_mm_wq);
+ return retval ?: nbytes;
+}
+
+/*
+ * These ascii lists should be read in a single call, by using a user
+ * buffer large enough to hold the entire map. If read in smaller
+ * chunks, there is no guarantee of atomicity. Since the display format
+ * used, list of ranges of sequential numbers, is variable length,
+ * and since these maps can change value dynamically, one could read
+ * gibberish by doing partial reads while a list was changing.
+ */
+static int cpuset_common_seq_show(struct seq_file *sf, void *v)
+{
+ struct cpuset *cs = css_cs(seq_css(sf));
+ cpuset_filetype_t type = seq_cft(sf)->private;
+ int ret = 0;
+
+ spin_lock_irq(&callback_lock);
+
+ switch (type) {
+ case FILE_CPULIST:
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
+ break;
+ case FILE_MEMLIST:
+ seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
+ break;
+ case FILE_EFFECTIVE_CPULIST:
+ seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
+ break;
+ case FILE_EFFECTIVE_MEMLIST:
+ seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
+ break;
+ default:
+ ret = -EINVAL;
+ }
+
+ spin_unlock_irq(&callback_lock);
+ return ret;
+}
+
+static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ switch (type) {
+ case FILE_CPU_EXCLUSIVE:
+ return is_cpu_exclusive(cs);
+ case FILE_MEM_EXCLUSIVE:
+ return is_mem_exclusive(cs);
+ case FILE_MEM_HARDWALL:
+ return is_mem_hardwall(cs);
+ case FILE_SCHED_LOAD_BALANCE:
+ return is_sched_load_balance(cs);
+ case FILE_MEMORY_MIGRATE:
+ return is_memory_migrate(cs);
+ case FILE_MEMORY_PRESSURE_ENABLED:
+ return cpuset_memory_pressure_enabled;
+ case FILE_MEMORY_PRESSURE:
+ return fmeter_getrate(&cs->fmeter);
+ case FILE_SPREAD_PAGE:
+ return is_spread_page(cs);
+ case FILE_SPREAD_SLAB:
+ return is_spread_slab(cs);
+ default:
+ BUG();
+ }
+
+ /* Unreachable but makes gcc happy */
+ return 0;
+}
+
+static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
+{
+ struct cpuset *cs = css_cs(css);
+ cpuset_filetype_t type = cft->private;
+ switch (type) {
+ case FILE_SCHED_RELAX_DOMAIN_LEVEL:
+ return cs->relax_domain_level;
+ default:
+ BUG();
+ }
+
+ /* Unrechable but makes gcc happy */
+ return 0;
+}
+
+
+/*
+ * for the common functions, 'private' gives the type of file
+ */
+
+static struct cftype files[] = {
+ {
+ .name = "cpus",
+ .seq_show = cpuset_common_seq_show,
+ .write = cpuset_write_resmask,
+ .max_write_len = (100U + 6 * NR_CPUS),
+ .private = FILE_CPULIST,
+ },
+
+ {
+ .name = "mems",
+ .seq_show = cpuset_common_seq_show,
+ .write = cpuset_write_resmask,
+ .max_write_len = (100U + 6 * MAX_NUMNODES),
+ .private = FILE_MEMLIST,
+ },
+
+ {
+ .name = "effective_cpus",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EFFECTIVE_CPULIST,
+ },
+
+ {
+ .name = "effective_mems",
+ .seq_show = cpuset_common_seq_show,
+ .private = FILE_EFFECTIVE_MEMLIST,
+ },
+
+ {
+ .name = "cpu_exclusive",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_CPU_EXCLUSIVE,
+ },
+
+ {
+ .name = "mem_exclusive",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEM_EXCLUSIVE,
+ },
+
+ {
+ .name = "mem_hardwall",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEM_HARDWALL,
+ },
+
+ {
+ .name = "sched_load_balance",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_SCHED_LOAD_BALANCE,
+ },
+
+ {
+ .name = "sched_relax_domain_level",
+ .read_s64 = cpuset_read_s64,
+ .write_s64 = cpuset_write_s64,
+ .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
+ },
+
+ {
+ .name = "memory_migrate",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEMORY_MIGRATE,
+ },
+
+ {
+ .name = "memory_pressure",
+ .read_u64 = cpuset_read_u64,
+ },
+
+ {
+ .name = "memory_spread_page",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_SPREAD_PAGE,
+ },
+
+ {
+ .name = "memory_spread_slab",
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_SPREAD_SLAB,
+ },
+
+ {
+ .name = "memory_pressure_enabled",
+ .flags = CFTYPE_ONLY_ON_ROOT,
+ .read_u64 = cpuset_read_u64,
+ .write_u64 = cpuset_write_u64,
+ .private = FILE_MEMORY_PRESSURE_ENABLED,
+ },
+
+ { } /* terminate */
+};
+
+/*
+ * cpuset_css_alloc - allocate a cpuset css
+ * cgrp: control group that the new cpuset will be part of
+ */
+
+static struct cgroup_subsys_state *
+cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct cpuset *cs;
+
+ if (!parent_css)
+ return &top_cpuset.css;
+
+ cs = kzalloc(sizeof(*cs), GFP_KERNEL);
+ if (!cs)
+ return ERR_PTR(-ENOMEM);
+ if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
+ goto free_cs;
+ if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
+ goto free_cpus;
+
+ set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
+ cpumask_clear(cs->cpus_allowed);
+ nodes_clear(cs->mems_allowed);
+ cpumask_clear(cs->effective_cpus);
+ nodes_clear(cs->effective_mems);
+ fmeter_init(&cs->fmeter);
+ cs->relax_domain_level = -1;
+
+ return &cs->css;
+
+free_cpus:
+ free_cpumask_var(cs->cpus_allowed);
+free_cs:
+ kfree(cs);
+ return ERR_PTR(-ENOMEM);
+}
+
+static int cpuset_css_online(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+ struct cpuset *parent = parent_cs(cs);
+ struct cpuset *tmp_cs;
+ struct cgroup_subsys_state *pos_css;
+
+ if (!parent)
+ return 0;
+
+ mutex_lock(&cpuset_mutex);
+
+ set_bit(CS_ONLINE, &cs->flags);
+ if (is_spread_page(parent))
+ set_bit(CS_SPREAD_PAGE, &cs->flags);
+ if (is_spread_slab(parent))
+ set_bit(CS_SPREAD_SLAB, &cs->flags);
+
+ cpuset_inc();
+
+ spin_lock_irq(&callback_lock);
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
+ cpumask_copy(cs->effective_cpus, parent->effective_cpus);
+ cs->effective_mems = parent->effective_mems;
+ }
+ spin_unlock_irq(&callback_lock);
+
+ if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
+ goto out_unlock;
+
+ /*
+ * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
+ * set. This flag handling is implemented in cgroup core for
+ * histrical reasons - the flag may be specified during mount.
+ *
+ * Currently, if any sibling cpusets have exclusive cpus or mem, we
+ * refuse to clone the configuration - thereby refusing the task to
+ * be entered, and as a result refusing the sys_unshare() or
+ * clone() which initiated it. If this becomes a problem for some
+ * users who wish to allow that scenario, then this could be
+ * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
+ * (and likewise for mems) to the new cgroup.
+ */
+ rcu_read_lock();
+ cpuset_for_each_child(tmp_cs, pos_css, parent) {
+ if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
+ rcu_read_unlock();
+ goto out_unlock;
+ }
+ }
+ rcu_read_unlock();
+
+ spin_lock_irq(&callback_lock);
+ cs->mems_allowed = parent->mems_allowed;
+ cs->effective_mems = parent->mems_allowed;
+ cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
+ cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
+ spin_unlock_irq(&callback_lock);
+out_unlock:
+ mutex_unlock(&cpuset_mutex);
+ return 0;
+}
+
+/*
+ * If the cpuset being removed has its flag 'sched_load_balance'
+ * enabled, then simulate turning sched_load_balance off, which
+ * will call rebuild_sched_domains_locked().
+ */
+
+static void cpuset_css_offline(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+
+ mutex_lock(&cpuset_mutex);
+
+ if (is_sched_load_balance(cs))
+ update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
+
+ cpuset_dec();
+ clear_bit(CS_ONLINE, &cs->flags);
+
+ mutex_unlock(&cpuset_mutex);
+}
+
+static void cpuset_css_free(struct cgroup_subsys_state *css)
+{
+ struct cpuset *cs = css_cs(css);
+
+ free_cpumask_var(cs->effective_cpus);
+ free_cpumask_var(cs->cpus_allowed);
+ kfree(cs);
+}
+
+static void cpuset_bind(struct cgroup_subsys_state *root_css)
+{
+ mutex_lock(&cpuset_mutex);
+ spin_lock_irq(&callback_lock);
+
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
+ cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
+ top_cpuset.mems_allowed = node_possible_map;
+ } else {
+ cpumask_copy(top_cpuset.cpus_allowed,
+ top_cpuset.effective_cpus);
+ top_cpuset.mems_allowed = top_cpuset.effective_mems;
+ }
+
+ spin_unlock_irq(&callback_lock);
+ mutex_unlock(&cpuset_mutex);
+}
+
+/*
+ * Make sure the new task conform to the current state of its parent,
+ * which could have been changed by cpuset just after it inherits the
+ * state from the parent and before it sits on the cgroup's task list.
+ */
+static void cpuset_fork(struct task_struct *task)
+{
+ if (task_css_is_root(task, cpuset_cgrp_id))
+ return;
+
+ set_cpus_allowed_ptr(task, ¤t->cpus_allowed);
+ task->mems_allowed = current->mems_allowed;
+}
+
+struct cgroup_subsys cpuset_cgrp_subsys = {
+ .css_alloc = cpuset_css_alloc,
+ .css_online = cpuset_css_online,
+ .css_offline = cpuset_css_offline,
+ .css_free = cpuset_css_free,
+ .can_attach = cpuset_can_attach,
+ .cancel_attach = cpuset_cancel_attach,
+ .attach = cpuset_attach,
+ .post_attach = cpuset_post_attach,
+ .bind = cpuset_bind,
+ .fork = cpuset_fork,
+ .legacy_cftypes = files,
+ .early_init = true,
+};
+
+/**
+ * cpuset_init - initialize cpusets at system boot
+ *
+ * Description: Initialize top_cpuset and the cpuset internal file system,
+ **/
+
+int __init cpuset_init(void)
+{
+ int err = 0;
+
+ if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
+ BUG();
+ if (!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL))
+ BUG();
+
+ cpumask_setall(top_cpuset.cpus_allowed);
+ nodes_setall(top_cpuset.mems_allowed);
+ cpumask_setall(top_cpuset.effective_cpus);
+ nodes_setall(top_cpuset.effective_mems);
+
+ fmeter_init(&top_cpuset.fmeter);
+ set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
+ top_cpuset.relax_domain_level = -1;
+
+ err = register_filesystem(&cpuset_fs_type);
+ if (err < 0)
+ return err;
+
+ if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
+ BUG();
+
+ return 0;
+}
+
+/*
+ * If CPU and/or memory hotplug handlers, below, unplug any CPUs
+ * or memory nodes, we need to walk over the cpuset hierarchy,
+ * removing that CPU or node from all cpusets. If this removes the
+ * last CPU or node from a cpuset, then move the tasks in the empty
+ * cpuset to its next-highest non-empty parent.
+ */
+static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
+{
+ struct cpuset *parent;
+
+ /*
+ * Find its next-highest non-empty parent, (top cpuset
+ * has online cpus, so can't be empty).
+ */
+ parent = parent_cs(cs);
+ while (cpumask_empty(parent->cpus_allowed) ||
+ nodes_empty(parent->mems_allowed))
+ parent = parent_cs(parent);
+
+ if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
+ pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
+ pr_cont_cgroup_name(cs->css.cgroup);
+ pr_cont("\n");
+ }
+}
+
+static void
+hotplug_update_tasks_legacy(struct cpuset *cs,
+ struct cpumask *new_cpus, nodemask_t *new_mems,
+ bool cpus_updated, bool mems_updated)
+{
+ bool is_empty;
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->cpus_allowed, new_cpus);
+ cpumask_copy(cs->effective_cpus, new_cpus);
+ cs->mems_allowed = *new_mems;
+ cs->effective_mems = *new_mems;
+ spin_unlock_irq(&callback_lock);
+
+ /*
+ * Don't call update_tasks_cpumask() if the cpuset becomes empty,
+ * as the tasks will be migratecd to an ancestor.
+ */
+ if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
+ update_tasks_cpumask(cs);
+ if (mems_updated && !nodes_empty(cs->mems_allowed))
+ update_tasks_nodemask(cs);
+
+ is_empty = cpumask_empty(cs->cpus_allowed) ||
+ nodes_empty(cs->mems_allowed);
+
+ mutex_unlock(&cpuset_mutex);
+
+ /*
+ * Move tasks to the nearest ancestor with execution resources,
+ * This is full cgroup operation which will also call back into
+ * cpuset. Should be done outside any lock.
+ */
+ if (is_empty)
+ remove_tasks_in_empty_cpuset(cs);
+
+ mutex_lock(&cpuset_mutex);
+}
+
+static void
+hotplug_update_tasks(struct cpuset *cs,
+ struct cpumask *new_cpus, nodemask_t *new_mems,
+ bool cpus_updated, bool mems_updated)
+{
+ if (cpumask_empty(new_cpus))
+ cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
+ if (nodes_empty(*new_mems))
+ *new_mems = parent_cs(cs)->effective_mems;
+
+ spin_lock_irq(&callback_lock);
+ cpumask_copy(cs->effective_cpus, new_cpus);
+ cs->effective_mems = *new_mems;
+ spin_unlock_irq(&callback_lock);
+
+ if (cpus_updated)
+ update_tasks_cpumask(cs);
+ if (mems_updated)
+ update_tasks_nodemask(cs);
+}
+
+/**
+ * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
+ * @cs: cpuset in interest
+ *
+ * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
+ * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
+ * all its tasks are moved to the nearest ancestor with both resources.
+ */
+static void cpuset_hotplug_update_tasks(struct cpuset *cs)
+{
+ static cpumask_t new_cpus;
+ static nodemask_t new_mems;
+ bool cpus_updated;
+ bool mems_updated;
+retry:
+ wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
+
+ mutex_lock(&cpuset_mutex);
+
+ /*
+ * We have raced with task attaching. We wait until attaching
+ * is finished, so we won't attach a task to an empty cpuset.
+ */
+ if (cs->attach_in_progress) {
+ mutex_unlock(&cpuset_mutex);
+ goto retry;
+ }
+
+ cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);
+ nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);
+
+ cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
+ mems_updated = !nodes_equal(new_mems, cs->effective_mems);
+
+ if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
+ hotplug_update_tasks(cs, &new_cpus, &new_mems,
+ cpus_updated, mems_updated);
+ else
+ hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
+ cpus_updated, mems_updated);
+
+ mutex_unlock(&cpuset_mutex);
+}
+
+/**
+ * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
+ *
+ * This function is called after either CPU or memory configuration has
+ * changed and updates cpuset accordingly. The top_cpuset is always
+ * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
+ * order to make cpusets transparent (of no affect) on systems that are
+ * actively using CPU hotplug but making no active use of cpusets.
+ *
+ * Non-root cpusets are only affected by offlining. If any CPUs or memory
+ * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
+ * all descendants.
+ *
+ * Note that CPU offlining during suspend is ignored. We don't modify
+ * cpusets across suspend/resume cycles at all.
+ */
+static void cpuset_hotplug_workfn(struct work_struct *work)
+{
+ static cpumask_t new_cpus;
+ static nodemask_t new_mems;
+ bool cpus_updated, mems_updated;
+ bool on_dfl = cgroup_subsys_on_dfl(cpuset_cgrp_subsys);
+
+ mutex_lock(&cpuset_mutex);
+
+ /* fetch the available cpus/mems and find out which changed how */
+ cpumask_copy(&new_cpus, cpu_active_mask);
+ new_mems = node_states[N_MEMORY];
+
+ cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
+ mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
+
+ /* synchronize cpus_allowed to cpu_active_mask */
+ if (cpus_updated) {
+ spin_lock_irq(&callback_lock);
+ if (!on_dfl)
+ cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
+ cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
+ spin_unlock_irq(&callback_lock);
+ /* we don't mess with cpumasks of tasks in top_cpuset */
+ }
+
+ /* synchronize mems_allowed to N_MEMORY */
+ if (mems_updated) {
+ spin_lock_irq(&callback_lock);
+ if (!on_dfl)
+ top_cpuset.mems_allowed = new_mems;
+ top_cpuset.effective_mems = new_mems;
+ spin_unlock_irq(&callback_lock);
+ update_tasks_nodemask(&top_cpuset);
+ }
+
+ mutex_unlock(&cpuset_mutex);
+
+ /* if cpus or mems changed, we need to propagate to descendants */
+ if (cpus_updated || mems_updated) {
+ struct cpuset *cs;
+ struct cgroup_subsys_state *pos_css;
+
+ rcu_read_lock();
+ cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
+ if (cs == &top_cpuset || !css_tryget_online(&cs->css))
+ continue;
+ rcu_read_unlock();
+
+ cpuset_hotplug_update_tasks(cs);
+
+ rcu_read_lock();
+ css_put(&cs->css);
+ }
+ rcu_read_unlock();
+ }
+
+ /* rebuild sched domains if cpus_allowed has changed */
+ if (cpus_updated)
+ rebuild_sched_domains();
+}
+
+void cpuset_update_active_cpus(bool cpu_online)
+{
+ /*
+ * We're inside cpu hotplug critical region which usually nests
+ * inside cgroup synchronization. Bounce actual hotplug processing
+ * to a work item to avoid reverse locking order.
+ *
+ * We still need to do partition_sched_domains() synchronously;
+ * otherwise, the scheduler will get confused and put tasks to the
+ * dead CPU. Fall back to the default single domain.
+ * cpuset_hotplug_workfn() will rebuild it as necessary.
+ */
+ partition_sched_domains(1, NULL, NULL);
+ schedule_work(&cpuset_hotplug_work);
+}
+
+/*
+ * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
+ * Call this routine anytime after node_states[N_MEMORY] changes.
+ * See cpuset_update_active_cpus() for CPU hotplug handling.
+ */
+static int cpuset_track_online_nodes(struct notifier_block *self,
+ unsigned long action, void *arg)
+{
+ schedule_work(&cpuset_hotplug_work);
+ return NOTIFY_OK;
+}
+
+static struct notifier_block cpuset_track_online_nodes_nb = {
+ .notifier_call = cpuset_track_online_nodes,
+ .priority = 10, /* ??! */
+};
+
+/**
+ * cpuset_init_smp - initialize cpus_allowed
+ *
+ * Description: Finish top cpuset after cpu, node maps are initialized
+ */
+void __init cpuset_init_smp(void)
+{
+ cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
+ top_cpuset.mems_allowed = node_states[N_MEMORY];
+ top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
+
+ cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
+ top_cpuset.effective_mems = node_states[N_MEMORY];
+
+ register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
+
+ cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
+ BUG_ON(!cpuset_migrate_mm_wq);
+}
+
+/**
+ * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
+ * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
+ * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
+ *
+ * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
+ * attached to the specified @tsk. Guaranteed to return some non-empty
+ * subset of cpu_online_mask, even if this means going outside the
+ * tasks cpuset.
+ **/
+
+void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&callback_lock, flags);
+ rcu_read_lock();
+ guarantee_online_cpus(task_cs(tsk), pmask);
+ rcu_read_unlock();
+ spin_unlock_irqrestore(&callback_lock, flags);
+}
+
+void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
+{
+ rcu_read_lock();
+ do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
+ rcu_read_unlock();
+
+ /*
+ * We own tsk->cpus_allowed, nobody can change it under us.
+ *
+ * But we used cs && cs->cpus_allowed lockless and thus can
+ * race with cgroup_attach_task() or update_cpumask() and get
+ * the wrong tsk->cpus_allowed. However, both cases imply the
+ * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
+ * which takes task_rq_lock().
+ *
+ * If we are called after it dropped the lock we must see all
+ * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
+ * set any mask even if it is not right from task_cs() pov,
+ * the pending set_cpus_allowed_ptr() will fix things.
+ *
+ * select_fallback_rq() will fix things ups and set cpu_possible_mask
+ * if required.
+ */
+}
+
+void __init cpuset_init_current_mems_allowed(void)
+{
+ nodes_setall(current->mems_allowed);
+}
+
+/**
+ * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
+ * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
+ *
+ * Description: Returns the nodemask_t mems_allowed of the cpuset
+ * attached to the specified @tsk. Guaranteed to return some non-empty
+ * subset of node_states[N_MEMORY], even if this means going outside the
+ * tasks cpuset.
+ **/
+
+nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
+{
+ nodemask_t mask;
+ unsigned long flags;
+
+ spin_lock_irqsave(&callback_lock, flags);
+ rcu_read_lock();
+ guarantee_online_mems(task_cs(tsk), &mask);
+ rcu_read_unlock();
+ spin_unlock_irqrestore(&callback_lock, flags);
+
+ return mask;
+}
+
+/**
+ * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
+ * @nodemask: the nodemask to be checked
+ *
+ * Are any of the nodes in the nodemask allowed in current->mems_allowed?
+ */
+int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
+{
+ return nodes_intersects(*nodemask, current->mems_allowed);
+}
+
+/*
+ * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
+ * mem_hardwall ancestor to the specified cpuset. Call holding
+ * callback_lock. If no ancestor is mem_exclusive or mem_hardwall
+ * (an unusual configuration), then returns the root cpuset.
+ */
+static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
+{
+ while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
+ cs = parent_cs(cs);
+ return cs;
+}
+
+/**
+ * cpuset_node_allowed - Can we allocate on a memory node?
+ * @node: is this an allowed node?
+ * @gfp_mask: memory allocation flags
+ *
+ * If we're in interrupt, yes, we can always allocate. If @node is set in
+ * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
+ * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
+ * yes. If current has access to memory reserves due to TIF_MEMDIE, yes.
+ * Otherwise, no.
+ *
+ * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
+ * and do not allow allocations outside the current tasks cpuset
+ * unless the task has been OOM killed as is marked TIF_MEMDIE.
+ * GFP_KERNEL allocations are not so marked, so can escape to the
+ * nearest enclosing hardwalled ancestor cpuset.
+ *
+ * Scanning up parent cpusets requires callback_lock. The
+ * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
+ * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
+ * current tasks mems_allowed came up empty on the first pass over
+ * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
+ * cpuset are short of memory, might require taking the callback_lock.
+ *
+ * The first call here from mm/page_alloc:get_page_from_freelist()
+ * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
+ * so no allocation on a node outside the cpuset is allowed (unless
+ * in interrupt, of course).
+ *
+ * The second pass through get_page_from_freelist() doesn't even call
+ * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
+ * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
+ * in alloc_flags. That logic and the checks below have the combined
+ * affect that:
+ * in_interrupt - any node ok (current task context irrelevant)
+ * GFP_ATOMIC - any node ok
+ * TIF_MEMDIE - any node ok
+ * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
+ * GFP_USER - only nodes in current tasks mems allowed ok.
+ */
+bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
+{
+ struct cpuset *cs; /* current cpuset ancestors */
+ int allowed; /* is allocation in zone z allowed? */
+ unsigned long flags;
+
+ if (in_interrupt())
+ return true;
+ if (node_isset(node, current->mems_allowed))
+ return true;
+ /*
+ * Allow tasks that have access to memory reserves because they have
+ * been OOM killed to get memory anywhere.
+ */
+ if (unlikely(test_thread_flag(TIF_MEMDIE)))
+ return true;
+ if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
+ return false;
+
+ if (current->flags & PF_EXITING) /* Let dying task have memory */
+ return true;
+
+ /* Not hardwall and node outside mems_allowed: scan up cpusets */
+ spin_lock_irqsave(&callback_lock, flags);
+
+ rcu_read_lock();
+ cs = nearest_hardwall_ancestor(task_cs(current));
+ allowed = node_isset(node, cs->mems_allowed);
+ rcu_read_unlock();
+
+ spin_unlock_irqrestore(&callback_lock, flags);
+ return allowed;
+}
+
+/**
+ * cpuset_mem_spread_node() - On which node to begin search for a file page
+ * cpuset_slab_spread_node() - On which node to begin search for a slab page
+ *
+ * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
+ * tasks in a cpuset with is_spread_page or is_spread_slab set),
+ * and if the memory allocation used cpuset_mem_spread_node()
+ * to determine on which node to start looking, as it will for
+ * certain page cache or slab cache pages such as used for file
+ * system buffers and inode caches, then instead of starting on the
+ * local node to look for a free page, rather spread the starting
+ * node around the tasks mems_allowed nodes.
+ *
+ * We don't have to worry about the returned node being offline
+ * because "it can't happen", and even if it did, it would be ok.
+ *
+ * The routines calling guarantee_online_mems() are careful to
+ * only set nodes in task->mems_allowed that are online. So it
+ * should not be possible for the following code to return an
+ * offline node. But if it did, that would be ok, as this routine
+ * is not returning the node where the allocation must be, only
+ * the node where the search should start. The zonelist passed to
+ * __alloc_pages() will include all nodes. If the slab allocator
+ * is passed an offline node, it will fall back to the local node.
+ * See kmem_cache_alloc_node().
+ */
+
+static int cpuset_spread_node(int *rotor)
+{
+ return *rotor = next_node_in(*rotor, current->mems_allowed);
+}
+
+int cpuset_mem_spread_node(void)
+{
+ if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
+ current->cpuset_mem_spread_rotor =
+ node_random(¤t->mems_allowed);
+
+ return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
+}
+
+int cpuset_slab_spread_node(void)
+{
+ if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
+ current->cpuset_slab_spread_rotor =
+ node_random(¤t->mems_allowed);
+
+ return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
+}
+
+EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
+
+/**
+ * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
+ * @tsk1: pointer to task_struct of some task.
+ * @tsk2: pointer to task_struct of some other task.
+ *
+ * Description: Return true if @tsk1's mems_allowed intersects the
+ * mems_allowed of @tsk2. Used by the OOM killer to determine if
+ * one of the task's memory usage might impact the memory available
+ * to the other.
+ **/
+
+int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
+ const struct task_struct *tsk2)
+{
+ return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
+}
+
+/**
+ * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
+ *
+ * Description: Prints current's name, cpuset name, and cached copy of its
+ * mems_allowed to the kernel log.
+ */
+void cpuset_print_current_mems_allowed(void)
+{
+ struct cgroup *cgrp;
+
+ rcu_read_lock();
+
+ cgrp = task_cs(current)->css.cgroup;
+ pr_info("%s cpuset=", current->comm);
+ pr_cont_cgroup_name(cgrp);
+ pr_cont(" mems_allowed=%*pbl\n",
+ nodemask_pr_args(¤t->mems_allowed));
+
+ rcu_read_unlock();
+}
+
+/*
+ * Collection of memory_pressure is suppressed unless
+ * this flag is enabled by writing "1" to the special
+ * cpuset file 'memory_pressure_enabled' in the root cpuset.
+ */
+
+int cpuset_memory_pressure_enabled __read_mostly;
+
+/**
+ * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
+ *
+ * Keep a running average of the rate of synchronous (direct)
+ * page reclaim efforts initiated by tasks in each cpuset.
+ *
+ * This represents the rate at which some task in the cpuset
+ * ran low on memory on all nodes it was allowed to use, and
+ * had to enter the kernels page reclaim code in an effort to
+ * create more free memory by tossing clean pages or swapping
+ * or writing dirty pages.
+ *
+ * Display to user space in the per-cpuset read-only file
+ * "memory_pressure". Value displayed is an integer
+ * representing the recent rate of entry into the synchronous
+ * (direct) page reclaim by any task attached to the cpuset.
+ **/
+
+void __cpuset_memory_pressure_bump(void)
+{
+ rcu_read_lock();
+ fmeter_markevent(&task_cs(current)->fmeter);
+ rcu_read_unlock();
+}
+
+#ifdef CONFIG_PROC_PID_CPUSET
+/*
+ * proc_cpuset_show()
+ * - Print tasks cpuset path into seq_file.
+ * - Used for /proc/<pid>/cpuset.
+ * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
+ * doesn't really matter if tsk->cpuset changes after we read it,
+ * and we take cpuset_mutex, keeping cpuset_attach() from changing it
+ * anyway.
+ */
+int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
+ struct pid *pid, struct task_struct *tsk)
+{
+ char *buf;
+ struct cgroup_subsys_state *css;
+ int retval;
+
+ retval = -ENOMEM;
+ buf = kmalloc(PATH_MAX, GFP_KERNEL);
+ if (!buf)
+ goto out;
+
+ css = task_get_css(tsk, cpuset_cgrp_id);
+ retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
+ current->nsproxy->cgroup_ns);
+ css_put(css);
+ if (retval >= PATH_MAX)
+ retval = -ENAMETOOLONG;
+ if (retval < 0)
+ goto out_free;
+ seq_puts(m, buf);
+ seq_putc(m, '\n');
+ retval = 0;
+out_free:
+ kfree(buf);
+out:
+ return retval;
+}
+#endif /* CONFIG_PROC_PID_CPUSET */
+
+/* Display task mems_allowed in /proc/<pid>/status file. */
+void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
+{
+ seq_printf(m, "Mems_allowed:\t%*pb\n",
+ nodemask_pr_args(&task->mems_allowed));
+ seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
+ nodemask_pr_args(&task->mems_allowed));
+}
--- /dev/null
+/*
+ * cgroup_freezer.c - control group freezer subsystem
+ *
+ * Copyright IBM Corporation, 2007
+ *
+ * Author : Cedric Le Goater <clg@fr.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2.1 of the GNU Lesser General Public License
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/cgroup.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+#include <linux/freezer.h>
+#include <linux/seq_file.h>
+#include <linux/mutex.h>
+
+/*
+ * A cgroup is freezing if any FREEZING flags are set. FREEZING_SELF is
+ * set if "FROZEN" is written to freezer.state cgroupfs file, and cleared
+ * for "THAWED". FREEZING_PARENT is set if the parent freezer is FREEZING
+ * for whatever reason. IOW, a cgroup has FREEZING_PARENT set if one of
+ * its ancestors has FREEZING_SELF set.
+ */
+enum freezer_state_flags {
+ CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */
+ CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */
+ CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */
+ CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */
+
+ /* mask for all FREEZING flags */
+ CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT,
+};
+
+struct freezer {
+ struct cgroup_subsys_state css;
+ unsigned int state;
+};
+
+static DEFINE_MUTEX(freezer_mutex);
+
+static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
+{
+ return css ? container_of(css, struct freezer, css) : NULL;
+}
+
+static inline struct freezer *task_freezer(struct task_struct *task)
+{
+ return css_freezer(task_css(task, freezer_cgrp_id));
+}
+
+static struct freezer *parent_freezer(struct freezer *freezer)
+{
+ return css_freezer(freezer->css.parent);
+}
+
+bool cgroup_freezing(struct task_struct *task)
+{
+ bool ret;
+
+ rcu_read_lock();
+ ret = task_freezer(task)->state & CGROUP_FREEZING;
+ rcu_read_unlock();
+
+ return ret;
+}
+
+static const char *freezer_state_strs(unsigned int state)
+{
+ if (state & CGROUP_FROZEN)
+ return "FROZEN";
+ if (state & CGROUP_FREEZING)
+ return "FREEZING";
+ return "THAWED";
+};
+
+static struct cgroup_subsys_state *
+freezer_css_alloc(struct cgroup_subsys_state *parent_css)
+{
+ struct freezer *freezer;
+
+ freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
+ if (!freezer)
+ return ERR_PTR(-ENOMEM);
+
+ return &freezer->css;
+}
+
+/**
+ * freezer_css_online - commit creation of a freezer css
+ * @css: css being created
+ *
+ * We're committing to creation of @css. Mark it online and inherit
+ * parent's freezing state while holding both parent's and our
+ * freezer->lock.
+ */
+static int freezer_css_online(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+ struct freezer *parent = parent_freezer(freezer);
+
+ mutex_lock(&freezer_mutex);
+
+ freezer->state |= CGROUP_FREEZER_ONLINE;
+
+ if (parent && (parent->state & CGROUP_FREEZING)) {
+ freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
+ atomic_inc(&system_freezing_cnt);
+ }
+
+ mutex_unlock(&freezer_mutex);
+ return 0;
+}
+
+/**
+ * freezer_css_offline - initiate destruction of a freezer css
+ * @css: css being destroyed
+ *
+ * @css is going away. Mark it dead and decrement system_freezing_count if
+ * it was holding one.
+ */
+static void freezer_css_offline(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ mutex_lock(&freezer_mutex);
+
+ if (freezer->state & CGROUP_FREEZING)
+ atomic_dec(&system_freezing_cnt);
+
+ freezer->state = 0;
+
+ mutex_unlock(&freezer_mutex);
+}
+
+static void freezer_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css_freezer(css));
+}
+
+/*
+ * Tasks can be migrated into a different freezer anytime regardless of its
+ * current state. freezer_attach() is responsible for making new tasks
+ * conform to the current state.
+ *
+ * Freezer state changes and task migration are synchronized via
+ * @freezer->lock. freezer_attach() makes the new tasks conform to the
+ * current state and all following state changes can see the new tasks.
+ */
+static void freezer_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *new_css;
+
+ mutex_lock(&freezer_mutex);
+
+ /*
+ * Make the new tasks conform to the current state of @new_css.
+ * For simplicity, when migrating any task to a FROZEN cgroup, we
+ * revert it to FREEZING and let update_if_frozen() determine the
+ * correct state later.
+ *
+ * Tasks in @tset are on @new_css but may not conform to its
+ * current state before executing the following - !frozen tasks may
+ * be visible in a FROZEN cgroup and frozen tasks in a THAWED one.
+ */
+ cgroup_taskset_for_each(task, new_css, tset) {
+ struct freezer *freezer = css_freezer(new_css);
+
+ if (!(freezer->state & CGROUP_FREEZING)) {
+ __thaw_task(task);
+ } else {
+ freeze_task(task);
+ /* clear FROZEN and propagate upwards */
+ while (freezer && (freezer->state & CGROUP_FROZEN)) {
+ freezer->state &= ~CGROUP_FROZEN;
+ freezer = parent_freezer(freezer);
+ }
+ }
+ }
+
+ mutex_unlock(&freezer_mutex);
+}
+
+/**
+ * freezer_fork - cgroup post fork callback
+ * @task: a task which has just been forked
+ *
+ * @task has just been created and should conform to the current state of
+ * the cgroup_freezer it belongs to. This function may race against
+ * freezer_attach(). Losing to freezer_attach() means that we don't have
+ * to do anything as freezer_attach() will put @task into the appropriate
+ * state.
+ */
+static void freezer_fork(struct task_struct *task)
+{
+ struct freezer *freezer;
+
+ /*
+ * The root cgroup is non-freezable, so we can skip locking the
+ * freezer. This is safe regardless of race with task migration.
+ * If we didn't race or won, skipping is obviously the right thing
+ * to do. If we lost and root is the new cgroup, noop is still the
+ * right thing to do.
+ */
+ if (task_css_is_root(task, freezer_cgrp_id))
+ return;
+
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+
+ freezer = task_freezer(task);
+ if (freezer->state & CGROUP_FREEZING)
+ freeze_task(task);
+
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+}
+
+/**
+ * update_if_frozen - update whether a cgroup finished freezing
+ * @css: css of interest
+ *
+ * Once FREEZING is initiated, transition to FROZEN is lazily updated by
+ * calling this function. If the current state is FREEZING but not FROZEN,
+ * this function checks whether all tasks of this cgroup and the descendant
+ * cgroups finished freezing and, if so, sets FROZEN.
+ *
+ * The caller is responsible for grabbing RCU read lock and calling
+ * update_if_frozen() on all descendants prior to invoking this function.
+ *
+ * Task states and freezer state might disagree while tasks are being
+ * migrated into or out of @css, so we can't verify task states against
+ * @freezer state here. See freezer_attach() for details.
+ */
+static void update_if_frozen(struct cgroup_subsys_state *css)
+{
+ struct freezer *freezer = css_freezer(css);
+ struct cgroup_subsys_state *pos;
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ lockdep_assert_held(&freezer_mutex);
+
+ if (!(freezer->state & CGROUP_FREEZING) ||
+ (freezer->state & CGROUP_FROZEN))
+ return;
+
+ /* are all (live) children frozen? */
+ rcu_read_lock();
+ css_for_each_child(pos, css) {
+ struct freezer *child = css_freezer(pos);
+
+ if ((child->state & CGROUP_FREEZER_ONLINE) &&
+ !(child->state & CGROUP_FROZEN)) {
+ rcu_read_unlock();
+ return;
+ }
+ }
+ rcu_read_unlock();
+
+ /* are all tasks frozen? */
+ css_task_iter_start(css, &it);
+
+ while ((task = css_task_iter_next(&it))) {
+ if (freezing(task)) {
+ /*
+ * freezer_should_skip() indicates that the task
+ * should be skipped when determining freezing
+ * completion. Consider it frozen in addition to
+ * the usual frozen condition.
+ */
+ if (!frozen(task) && !freezer_should_skip(task))
+ goto out_iter_end;
+ }
+ }
+
+ freezer->state |= CGROUP_FROZEN;
+out_iter_end:
+ css_task_iter_end(&it);
+}
+
+static int freezer_read(struct seq_file *m, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(m), *pos;
+
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+
+ /* update states bottom-up */
+ css_for_each_descendant_post(pos, css) {
+ if (!css_tryget_online(pos))
+ continue;
+ rcu_read_unlock();
+
+ update_if_frozen(pos);
+
+ rcu_read_lock();
+ css_put(pos);
+ }
+
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+
+ seq_puts(m, freezer_state_strs(css_freezer(css)->state));
+ seq_putc(m, '\n');
+ return 0;
+}
+
+static void freeze_cgroup(struct freezer *freezer)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&freezer->css, &it);
+ while ((task = css_task_iter_next(&it)))
+ freeze_task(task);
+ css_task_iter_end(&it);
+}
+
+static void unfreeze_cgroup(struct freezer *freezer)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ css_task_iter_start(&freezer->css, &it);
+ while ((task = css_task_iter_next(&it)))
+ __thaw_task(task);
+ css_task_iter_end(&it);
+}
+
+/**
+ * freezer_apply_state - apply state change to a single cgroup_freezer
+ * @freezer: freezer to apply state change to
+ * @freeze: whether to freeze or unfreeze
+ * @state: CGROUP_FREEZING_* flag to set or clear
+ *
+ * Set or clear @state on @cgroup according to @freeze, and perform
+ * freezing or thawing as necessary.
+ */
+static void freezer_apply_state(struct freezer *freezer, bool freeze,
+ unsigned int state)
+{
+ /* also synchronizes against task migration, see freezer_attach() */
+ lockdep_assert_held(&freezer_mutex);
+
+ if (!(freezer->state & CGROUP_FREEZER_ONLINE))
+ return;
+
+ if (freeze) {
+ if (!(freezer->state & CGROUP_FREEZING))
+ atomic_inc(&system_freezing_cnt);
+ freezer->state |= state;
+ freeze_cgroup(freezer);
+ } else {
+ bool was_freezing = freezer->state & CGROUP_FREEZING;
+
+ freezer->state &= ~state;
+
+ if (!(freezer->state & CGROUP_FREEZING)) {
+ if (was_freezing)
+ atomic_dec(&system_freezing_cnt);
+ freezer->state &= ~CGROUP_FROZEN;
+ unfreeze_cgroup(freezer);
+ }
+ }
+}
+
+/**
+ * freezer_change_state - change the freezing state of a cgroup_freezer
+ * @freezer: freezer of interest
+ * @freeze: whether to freeze or thaw
+ *
+ * Freeze or thaw @freezer according to @freeze. The operations are
+ * recursive - all descendants of @freezer will be affected.
+ */
+static void freezer_change_state(struct freezer *freezer, bool freeze)
+{
+ struct cgroup_subsys_state *pos;
+
+ /*
+ * Update all its descendants in pre-order traversal. Each
+ * descendant will try to inherit its parent's FREEZING state as
+ * CGROUP_FREEZING_PARENT.
+ */
+ mutex_lock(&freezer_mutex);
+ rcu_read_lock();
+ css_for_each_descendant_pre(pos, &freezer->css) {
+ struct freezer *pos_f = css_freezer(pos);
+ struct freezer *parent = parent_freezer(pos_f);
+
+ if (!css_tryget_online(pos))
+ continue;
+ rcu_read_unlock();
+
+ if (pos_f == freezer)
+ freezer_apply_state(pos_f, freeze,
+ CGROUP_FREEZING_SELF);
+ else
+ freezer_apply_state(pos_f,
+ parent->state & CGROUP_FREEZING,
+ CGROUP_FREEZING_PARENT);
+
+ rcu_read_lock();
+ css_put(pos);
+ }
+ rcu_read_unlock();
+ mutex_unlock(&freezer_mutex);
+}
+
+static ssize_t freezer_write(struct kernfs_open_file *of,
+ char *buf, size_t nbytes, loff_t off)
+{
+ bool freeze;
+
+ buf = strstrip(buf);
+
+ if (strcmp(buf, freezer_state_strs(0)) == 0)
+ freeze = false;
+ else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)
+ freeze = true;
+ else
+ return -EINVAL;
+
+ freezer_change_state(css_freezer(of_css(of)), freeze);
+ return nbytes;
+}
+
+static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_SELF);
+}
+
+static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct freezer *freezer = css_freezer(css);
+
+ return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
+}
+
+static struct cftype files[] = {
+ {
+ .name = "state",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .seq_show = freezer_read,
+ .write = freezer_write,
+ },
+ {
+ .name = "self_freezing",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = freezer_self_freezing_read,
+ },
+ {
+ .name = "parent_freezing",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .read_u64 = freezer_parent_freezing_read,
+ },
+ { } /* terminate */
+};
+
+struct cgroup_subsys freezer_cgrp_subsys = {
+ .css_alloc = freezer_css_alloc,
+ .css_online = freezer_css_online,
+ .css_offline = freezer_css_offline,
+ .css_free = freezer_css_free,
+ .attach = freezer_attach,
+ .fork = freezer_fork,
+ .legacy_cftypes = files,
+};
--- /dev/null
+/*
+ * Process number limiting controller for cgroups.
+ *
+ * Used to allow a cgroup hierarchy to stop any new processes from fork()ing
+ * after a certain limit is reached.
+ *
+ * Since it is trivial to hit the task limit without hitting any kmemcg limits
+ * in place, PIDs are a fundamental resource. As such, PID exhaustion must be
+ * preventable in the scope of a cgroup hierarchy by allowing resource limiting
+ * of the number of tasks in a cgroup.
+ *
+ * In order to use the `pids` controller, set the maximum number of tasks in
+ * pids.max (this is not available in the root cgroup for obvious reasons). The
+ * number of processes currently in the cgroup is given by pids.current.
+ * Organisational operations are not blocked by cgroup policies, so it is
+ * possible to have pids.current > pids.max. However, it is not possible to
+ * violate a cgroup policy through fork(). fork() will return -EAGAIN if forking
+ * would cause a cgroup policy to be violated.
+ *
+ * To set a cgroup to have no limit, set pids.max to "max". This is the default
+ * for all new cgroups (N.B. that PID limits are hierarchical, so the most
+ * stringent limit in the hierarchy is followed).
+ *
+ * pids.current tracks all child cgroup hierarchies, so parent/pids.current is
+ * a superset of parent/child/pids.current.
+ *
+ * Copyright (C) 2015 Aleksa Sarai <cyphar@cyphar.com>
+ *
+ * This file is subject to the terms and conditions of version 2 of the GNU
+ * General Public License. See the file COPYING in the main directory of the
+ * Linux distribution for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/threads.h>
+#include <linux/atomic.h>
+#include <linux/cgroup.h>
+#include <linux/slab.h>
+
+#define PIDS_MAX (PID_MAX_LIMIT + 1ULL)
+#define PIDS_MAX_STR "max"
+
+struct pids_cgroup {
+ struct cgroup_subsys_state css;
+
+ /*
+ * Use 64-bit types so that we can safely represent "max" as
+ * %PIDS_MAX = (%PID_MAX_LIMIT + 1).
+ */
+ atomic64_t counter;
+ int64_t limit;
+
+ /* Handle for "pids.events" */
+ struct cgroup_file events_file;
+
+ /* Number of times fork failed because limit was hit. */
+ atomic64_t events_limit;
+};
+
+static struct pids_cgroup *css_pids(struct cgroup_subsys_state *css)
+{
+ return container_of(css, struct pids_cgroup, css);
+}
+
+static struct pids_cgroup *parent_pids(struct pids_cgroup *pids)
+{
+ return css_pids(pids->css.parent);
+}
+
+static struct cgroup_subsys_state *
+pids_css_alloc(struct cgroup_subsys_state *parent)
+{
+ struct pids_cgroup *pids;
+
+ pids = kzalloc(sizeof(struct pids_cgroup), GFP_KERNEL);
+ if (!pids)
+ return ERR_PTR(-ENOMEM);
+
+ pids->limit = PIDS_MAX;
+ atomic64_set(&pids->counter, 0);
+ atomic64_set(&pids->events_limit, 0);
+ return &pids->css;
+}
+
+static void pids_css_free(struct cgroup_subsys_state *css)
+{
+ kfree(css_pids(css));
+}
+
+/**
+ * pids_cancel - uncharge the local pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to cancel
+ *
+ * This function will WARN if the pid count goes under 0, because such a case is
+ * a bug in the pids controller proper.
+ */
+static void pids_cancel(struct pids_cgroup *pids, int num)
+{
+ /*
+ * A negative count (or overflow for that matter) is invalid,
+ * and indicates a bug in the `pids` controller proper.
+ */
+ WARN_ON_ONCE(atomic64_add_negative(-num, &pids->counter));
+}
+
+/**
+ * pids_uncharge - hierarchically uncharge the pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to uncharge
+ */
+static void pids_uncharge(struct pids_cgroup *pids, int num)
+{
+ struct pids_cgroup *p;
+
+ for (p = pids; parent_pids(p); p = parent_pids(p))
+ pids_cancel(p, num);
+}
+
+/**
+ * pids_charge - hierarchically charge the pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to charge
+ *
+ * This function does *not* follow the pid limit set. It cannot fail and the new
+ * pid count may exceed the limit. This is only used for reverting failed
+ * attaches, where there is no other way out than violating the limit.
+ */
+static void pids_charge(struct pids_cgroup *pids, int num)
+{
+ struct pids_cgroup *p;
+
+ for (p = pids; parent_pids(p); p = parent_pids(p))
+ atomic64_add(num, &p->counter);
+}
+
+/**
+ * pids_try_charge - hierarchically try to charge the pid count
+ * @pids: the pid cgroup state
+ * @num: the number of pids to charge
+ *
+ * This function follows the set limit. It will fail if the charge would cause
+ * the new value to exceed the hierarchical limit. Returns 0 if the charge
+ * succeeded, otherwise -EAGAIN.
+ */
+static int pids_try_charge(struct pids_cgroup *pids, int num)
+{
+ struct pids_cgroup *p, *q;
+
+ for (p = pids; parent_pids(p); p = parent_pids(p)) {
+ int64_t new = atomic64_add_return(num, &p->counter);
+
+ /*
+ * Since new is capped to the maximum number of pid_t, if
+ * p->limit is %PIDS_MAX then we know that this test will never
+ * fail.
+ */
+ if (new > p->limit)
+ goto revert;
+ }
+
+ return 0;
+
+revert:
+ for (q = pids; q != p; q = parent_pids(q))
+ pids_cancel(q, num);
+ pids_cancel(p, num);
+
+ return -EAGAIN;
+}
+
+static int pids_can_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *dst_css;
+
+ cgroup_taskset_for_each(task, dst_css, tset) {
+ struct pids_cgroup *pids = css_pids(dst_css);
+ struct cgroup_subsys_state *old_css;
+ struct pids_cgroup *old_pids;
+
+ /*
+ * No need to pin @old_css between here and cancel_attach()
+ * because cgroup core protects it from being freed before
+ * the migration completes or fails.
+ */
+ old_css = task_css(task, pids_cgrp_id);
+ old_pids = css_pids(old_css);
+
+ pids_charge(pids, 1);
+ pids_uncharge(old_pids, 1);
+ }
+
+ return 0;
+}
+
+static void pids_cancel_attach(struct cgroup_taskset *tset)
+{
+ struct task_struct *task;
+ struct cgroup_subsys_state *dst_css;
+
+ cgroup_taskset_for_each(task, dst_css, tset) {
+ struct pids_cgroup *pids = css_pids(dst_css);
+ struct cgroup_subsys_state *old_css;
+ struct pids_cgroup *old_pids;
+
+ old_css = task_css(task, pids_cgrp_id);
+ old_pids = css_pids(old_css);
+
+ pids_charge(old_pids, 1);
+ pids_uncharge(pids, 1);
+ }
+}
+
+/*
+ * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies
+ * on threadgroup_change_begin() held by the copy_process().
+ */
+static int pids_can_fork(struct task_struct *task)
+{
+ struct cgroup_subsys_state *css;
+ struct pids_cgroup *pids;
+ int err;
+
+ css = task_css_check(current, pids_cgrp_id, true);
+ pids = css_pids(css);
+ err = pids_try_charge(pids, 1);
+ if (err) {
+ /* Only log the first time events_limit is incremented. */
+ if (atomic64_inc_return(&pids->events_limit) == 1) {
+ pr_info("cgroup: fork rejected by pids controller in ");
+ pr_cont_cgroup_path(task_cgroup(current, pids_cgrp_id));
+ pr_cont("\n");
+ }
+ cgroup_file_notify(&pids->events_file);
+ }
+ return err;
+}
+
+static void pids_cancel_fork(struct task_struct *task)
+{
+ struct cgroup_subsys_state *css;
+ struct pids_cgroup *pids;
+
+ css = task_css_check(current, pids_cgrp_id, true);
+ pids = css_pids(css);
+ pids_uncharge(pids, 1);
+}
+
+static void pids_free(struct task_struct *task)
+{
+ struct pids_cgroup *pids = css_pids(task_css(task, pids_cgrp_id));
+
+ pids_uncharge(pids, 1);
+}
+
+static ssize_t pids_max_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ struct cgroup_subsys_state *css = of_css(of);
+ struct pids_cgroup *pids = css_pids(css);
+ int64_t limit;
+ int err;
+
+ buf = strstrip(buf);
+ if (!strcmp(buf, PIDS_MAX_STR)) {
+ limit = PIDS_MAX;
+ goto set_limit;
+ }
+
+ err = kstrtoll(buf, 0, &limit);
+ if (err)
+ return err;
+
+ if (limit < 0 || limit >= PIDS_MAX)
+ return -EINVAL;
+
+set_limit:
+ /*
+ * Limit updates don't need to be mutex'd, since it isn't
+ * critical that any racing fork()s follow the new limit.
+ */
+ pids->limit = limit;
+ return nbytes;
+}
+
+static int pids_max_show(struct seq_file *sf, void *v)
+{
+ struct cgroup_subsys_state *css = seq_css(sf);
+ struct pids_cgroup *pids = css_pids(css);
+ int64_t limit = pids->limit;
+
+ if (limit >= PIDS_MAX)
+ seq_printf(sf, "%s\n", PIDS_MAX_STR);
+ else
+ seq_printf(sf, "%lld\n", limit);
+
+ return 0;
+}
+
+static s64 pids_current_read(struct cgroup_subsys_state *css,
+ struct cftype *cft)
+{
+ struct pids_cgroup *pids = css_pids(css);
+
+ return atomic64_read(&pids->counter);
+}
+
+static int pids_events_show(struct seq_file *sf, void *v)
+{
+ struct pids_cgroup *pids = css_pids(seq_css(sf));
+
+ seq_printf(sf, "max %lld\n", (s64)atomic64_read(&pids->events_limit));
+ return 0;
+}
+
+static struct cftype pids_files[] = {
+ {
+ .name = "max",
+ .write = pids_max_write,
+ .seq_show = pids_max_show,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "current",
+ .read_s64 = pids_current_read,
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ {
+ .name = "events",
+ .seq_show = pids_events_show,
+ .file_offset = offsetof(struct pids_cgroup, events_file),
+ .flags = CFTYPE_NOT_ON_ROOT,
+ },
+ { } /* terminate */
+};
+
+struct cgroup_subsys pids_cgrp_subsys = {
+ .css_alloc = pids_css_alloc,
+ .css_free = pids_css_free,
+ .can_attach = pids_can_attach,
+ .cancel_attach = pids_cancel_attach,
+ .can_fork = pids_can_fork,
+ .cancel_fork = pids_cancel_fork,
+ .free = pids_free,
+ .legacy_cftypes = pids_files,
+ .dfl_cftypes = pids_files,
+};
+++ /dev/null
-/*
- * cgroup_freezer.c - control group freezer subsystem
- *
- * Copyright IBM Corporation, 2007
- *
- * Author : Cedric Le Goater <clg@fr.ibm.com>
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of version 2.1 of the GNU Lesser General Public License
- * as published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it would be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- */
-
-#include <linux/export.h>
-#include <linux/slab.h>
-#include <linux/cgroup.h>
-#include <linux/fs.h>
-#include <linux/uaccess.h>
-#include <linux/freezer.h>
-#include <linux/seq_file.h>
-#include <linux/mutex.h>
-
-/*
- * A cgroup is freezing if any FREEZING flags are set. FREEZING_SELF is
- * set if "FROZEN" is written to freezer.state cgroupfs file, and cleared
- * for "THAWED". FREEZING_PARENT is set if the parent freezer is FREEZING
- * for whatever reason. IOW, a cgroup has FREEZING_PARENT set if one of
- * its ancestors has FREEZING_SELF set.
- */
-enum freezer_state_flags {
- CGROUP_FREEZER_ONLINE = (1 << 0), /* freezer is fully online */
- CGROUP_FREEZING_SELF = (1 << 1), /* this freezer is freezing */
- CGROUP_FREEZING_PARENT = (1 << 2), /* the parent freezer is freezing */
- CGROUP_FROZEN = (1 << 3), /* this and its descendants frozen */
-
- /* mask for all FREEZING flags */
- CGROUP_FREEZING = CGROUP_FREEZING_SELF | CGROUP_FREEZING_PARENT,
-};
-
-struct freezer {
- struct cgroup_subsys_state css;
- unsigned int state;
-};
-
-static DEFINE_MUTEX(freezer_mutex);
-
-static inline struct freezer *css_freezer(struct cgroup_subsys_state *css)
-{
- return css ? container_of(css, struct freezer, css) : NULL;
-}
-
-static inline struct freezer *task_freezer(struct task_struct *task)
-{
- return css_freezer(task_css(task, freezer_cgrp_id));
-}
-
-static struct freezer *parent_freezer(struct freezer *freezer)
-{
- return css_freezer(freezer->css.parent);
-}
-
-bool cgroup_freezing(struct task_struct *task)
-{
- bool ret;
-
- rcu_read_lock();
- ret = task_freezer(task)->state & CGROUP_FREEZING;
- rcu_read_unlock();
-
- return ret;
-}
-
-static const char *freezer_state_strs(unsigned int state)
-{
- if (state & CGROUP_FROZEN)
- return "FROZEN";
- if (state & CGROUP_FREEZING)
- return "FREEZING";
- return "THAWED";
-};
-
-static struct cgroup_subsys_state *
-freezer_css_alloc(struct cgroup_subsys_state *parent_css)
-{
- struct freezer *freezer;
-
- freezer = kzalloc(sizeof(struct freezer), GFP_KERNEL);
- if (!freezer)
- return ERR_PTR(-ENOMEM);
-
- return &freezer->css;
-}
-
-/**
- * freezer_css_online - commit creation of a freezer css
- * @css: css being created
- *
- * We're committing to creation of @css. Mark it online and inherit
- * parent's freezing state while holding both parent's and our
- * freezer->lock.
- */
-static int freezer_css_online(struct cgroup_subsys_state *css)
-{
- struct freezer *freezer = css_freezer(css);
- struct freezer *parent = parent_freezer(freezer);
-
- mutex_lock(&freezer_mutex);
-
- freezer->state |= CGROUP_FREEZER_ONLINE;
-
- if (parent && (parent->state & CGROUP_FREEZING)) {
- freezer->state |= CGROUP_FREEZING_PARENT | CGROUP_FROZEN;
- atomic_inc(&system_freezing_cnt);
- }
-
- mutex_unlock(&freezer_mutex);
- return 0;
-}
-
-/**
- * freezer_css_offline - initiate destruction of a freezer css
- * @css: css being destroyed
- *
- * @css is going away. Mark it dead and decrement system_freezing_count if
- * it was holding one.
- */
-static void freezer_css_offline(struct cgroup_subsys_state *css)
-{
- struct freezer *freezer = css_freezer(css);
-
- mutex_lock(&freezer_mutex);
-
- if (freezer->state & CGROUP_FREEZING)
- atomic_dec(&system_freezing_cnt);
-
- freezer->state = 0;
-
- mutex_unlock(&freezer_mutex);
-}
-
-static void freezer_css_free(struct cgroup_subsys_state *css)
-{
- kfree(css_freezer(css));
-}
-
-/*
- * Tasks can be migrated into a different freezer anytime regardless of its
- * current state. freezer_attach() is responsible for making new tasks
- * conform to the current state.
- *
- * Freezer state changes and task migration are synchronized via
- * @freezer->lock. freezer_attach() makes the new tasks conform to the
- * current state and all following state changes can see the new tasks.
- */
-static void freezer_attach(struct cgroup_taskset *tset)
-{
- struct task_struct *task;
- struct cgroup_subsys_state *new_css;
-
- mutex_lock(&freezer_mutex);
-
- /*
- * Make the new tasks conform to the current state of @new_css.
- * For simplicity, when migrating any task to a FROZEN cgroup, we
- * revert it to FREEZING and let update_if_frozen() determine the
- * correct state later.
- *
- * Tasks in @tset are on @new_css but may not conform to its
- * current state before executing the following - !frozen tasks may
- * be visible in a FROZEN cgroup and frozen tasks in a THAWED one.
- */
- cgroup_taskset_for_each(task, new_css, tset) {
- struct freezer *freezer = css_freezer(new_css);
-
- if (!(freezer->state & CGROUP_FREEZING)) {
- __thaw_task(task);
- } else {
- freeze_task(task);
- /* clear FROZEN and propagate upwards */
- while (freezer && (freezer->state & CGROUP_FROZEN)) {
- freezer->state &= ~CGROUP_FROZEN;
- freezer = parent_freezer(freezer);
- }
- }
- }
-
- mutex_unlock(&freezer_mutex);
-}
-
-/**
- * freezer_fork - cgroup post fork callback
- * @task: a task which has just been forked
- *
- * @task has just been created and should conform to the current state of
- * the cgroup_freezer it belongs to. This function may race against
- * freezer_attach(). Losing to freezer_attach() means that we don't have
- * to do anything as freezer_attach() will put @task into the appropriate
- * state.
- */
-static void freezer_fork(struct task_struct *task)
-{
- struct freezer *freezer;
-
- /*
- * The root cgroup is non-freezable, so we can skip locking the
- * freezer. This is safe regardless of race with task migration.
- * If we didn't race or won, skipping is obviously the right thing
- * to do. If we lost and root is the new cgroup, noop is still the
- * right thing to do.
- */
- if (task_css_is_root(task, freezer_cgrp_id))
- return;
-
- mutex_lock(&freezer_mutex);
- rcu_read_lock();
-
- freezer = task_freezer(task);
- if (freezer->state & CGROUP_FREEZING)
- freeze_task(task);
-
- rcu_read_unlock();
- mutex_unlock(&freezer_mutex);
-}
-
-/**
- * update_if_frozen - update whether a cgroup finished freezing
- * @css: css of interest
- *
- * Once FREEZING is initiated, transition to FROZEN is lazily updated by
- * calling this function. If the current state is FREEZING but not FROZEN,
- * this function checks whether all tasks of this cgroup and the descendant
- * cgroups finished freezing and, if so, sets FROZEN.
- *
- * The caller is responsible for grabbing RCU read lock and calling
- * update_if_frozen() on all descendants prior to invoking this function.
- *
- * Task states and freezer state might disagree while tasks are being
- * migrated into or out of @css, so we can't verify task states against
- * @freezer state here. See freezer_attach() for details.
- */
-static void update_if_frozen(struct cgroup_subsys_state *css)
-{
- struct freezer *freezer = css_freezer(css);
- struct cgroup_subsys_state *pos;
- struct css_task_iter it;
- struct task_struct *task;
-
- lockdep_assert_held(&freezer_mutex);
-
- if (!(freezer->state & CGROUP_FREEZING) ||
- (freezer->state & CGROUP_FROZEN))
- return;
-
- /* are all (live) children frozen? */
- rcu_read_lock();
- css_for_each_child(pos, css) {
- struct freezer *child = css_freezer(pos);
-
- if ((child->state & CGROUP_FREEZER_ONLINE) &&
- !(child->state & CGROUP_FROZEN)) {
- rcu_read_unlock();
- return;
- }
- }
- rcu_read_unlock();
-
- /* are all tasks frozen? */
- css_task_iter_start(css, &it);
-
- while ((task = css_task_iter_next(&it))) {
- if (freezing(task)) {
- /*
- * freezer_should_skip() indicates that the task
- * should be skipped when determining freezing
- * completion. Consider it frozen in addition to
- * the usual frozen condition.
- */
- if (!frozen(task) && !freezer_should_skip(task))
- goto out_iter_end;
- }
- }
-
- freezer->state |= CGROUP_FROZEN;
-out_iter_end:
- css_task_iter_end(&it);
-}
-
-static int freezer_read(struct seq_file *m, void *v)
-{
- struct cgroup_subsys_state *css = seq_css(m), *pos;
-
- mutex_lock(&freezer_mutex);
- rcu_read_lock();
-
- /* update states bottom-up */
- css_for_each_descendant_post(pos, css) {
- if (!css_tryget_online(pos))
- continue;
- rcu_read_unlock();
-
- update_if_frozen(pos);
-
- rcu_read_lock();
- css_put(pos);
- }
-
- rcu_read_unlock();
- mutex_unlock(&freezer_mutex);
-
- seq_puts(m, freezer_state_strs(css_freezer(css)->state));
- seq_putc(m, '\n');
- return 0;
-}
-
-static void freeze_cgroup(struct freezer *freezer)
-{
- struct css_task_iter it;
- struct task_struct *task;
-
- css_task_iter_start(&freezer->css, &it);
- while ((task = css_task_iter_next(&it)))
- freeze_task(task);
- css_task_iter_end(&it);
-}
-
-static void unfreeze_cgroup(struct freezer *freezer)
-{
- struct css_task_iter it;
- struct task_struct *task;
-
- css_task_iter_start(&freezer->css, &it);
- while ((task = css_task_iter_next(&it)))
- __thaw_task(task);
- css_task_iter_end(&it);
-}
-
-/**
- * freezer_apply_state - apply state change to a single cgroup_freezer
- * @freezer: freezer to apply state change to
- * @freeze: whether to freeze or unfreeze
- * @state: CGROUP_FREEZING_* flag to set or clear
- *
- * Set or clear @state on @cgroup according to @freeze, and perform
- * freezing or thawing as necessary.
- */
-static void freezer_apply_state(struct freezer *freezer, bool freeze,
- unsigned int state)
-{
- /* also synchronizes against task migration, see freezer_attach() */
- lockdep_assert_held(&freezer_mutex);
-
- if (!(freezer->state & CGROUP_FREEZER_ONLINE))
- return;
-
- if (freeze) {
- if (!(freezer->state & CGROUP_FREEZING))
- atomic_inc(&system_freezing_cnt);
- freezer->state |= state;
- freeze_cgroup(freezer);
- } else {
- bool was_freezing = freezer->state & CGROUP_FREEZING;
-
- freezer->state &= ~state;
-
- if (!(freezer->state & CGROUP_FREEZING)) {
- if (was_freezing)
- atomic_dec(&system_freezing_cnt);
- freezer->state &= ~CGROUP_FROZEN;
- unfreeze_cgroup(freezer);
- }
- }
-}
-
-/**
- * freezer_change_state - change the freezing state of a cgroup_freezer
- * @freezer: freezer of interest
- * @freeze: whether to freeze or thaw
- *
- * Freeze or thaw @freezer according to @freeze. The operations are
- * recursive - all descendants of @freezer will be affected.
- */
-static void freezer_change_state(struct freezer *freezer, bool freeze)
-{
- struct cgroup_subsys_state *pos;
-
- /*
- * Update all its descendants in pre-order traversal. Each
- * descendant will try to inherit its parent's FREEZING state as
- * CGROUP_FREEZING_PARENT.
- */
- mutex_lock(&freezer_mutex);
- rcu_read_lock();
- css_for_each_descendant_pre(pos, &freezer->css) {
- struct freezer *pos_f = css_freezer(pos);
- struct freezer *parent = parent_freezer(pos_f);
-
- if (!css_tryget_online(pos))
- continue;
- rcu_read_unlock();
-
- if (pos_f == freezer)
- freezer_apply_state(pos_f, freeze,
- CGROUP_FREEZING_SELF);
- else
- freezer_apply_state(pos_f,
- parent->state & CGROUP_FREEZING,
- CGROUP_FREEZING_PARENT);
-
- rcu_read_lock();
- css_put(pos);
- }
- rcu_read_unlock();
- mutex_unlock(&freezer_mutex);
-}
-
-static ssize_t freezer_write(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- bool freeze;
-
- buf = strstrip(buf);
-
- if (strcmp(buf, freezer_state_strs(0)) == 0)
- freeze = false;
- else if (strcmp(buf, freezer_state_strs(CGROUP_FROZEN)) == 0)
- freeze = true;
- else
- return -EINVAL;
-
- freezer_change_state(css_freezer(of_css(of)), freeze);
- return nbytes;
-}
-
-static u64 freezer_self_freezing_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct freezer *freezer = css_freezer(css);
-
- return (bool)(freezer->state & CGROUP_FREEZING_SELF);
-}
-
-static u64 freezer_parent_freezing_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct freezer *freezer = css_freezer(css);
-
- return (bool)(freezer->state & CGROUP_FREEZING_PARENT);
-}
-
-static struct cftype files[] = {
- {
- .name = "state",
- .flags = CFTYPE_NOT_ON_ROOT,
- .seq_show = freezer_read,
- .write = freezer_write,
- },
- {
- .name = "self_freezing",
- .flags = CFTYPE_NOT_ON_ROOT,
- .read_u64 = freezer_self_freezing_read,
- },
- {
- .name = "parent_freezing",
- .flags = CFTYPE_NOT_ON_ROOT,
- .read_u64 = freezer_parent_freezing_read,
- },
- { } /* terminate */
-};
-
-struct cgroup_subsys freezer_cgrp_subsys = {
- .css_alloc = freezer_css_alloc,
- .css_online = freezer_css_online,
- .css_offline = freezer_css_offline,
- .css_free = freezer_css_free,
- .attach = freezer_attach,
- .fork = freezer_fork,
- .legacy_cftypes = files,
-};
+++ /dev/null
-/*
- * Process number limiting controller for cgroups.
- *
- * Used to allow a cgroup hierarchy to stop any new processes from fork()ing
- * after a certain limit is reached.
- *
- * Since it is trivial to hit the task limit without hitting any kmemcg limits
- * in place, PIDs are a fundamental resource. As such, PID exhaustion must be
- * preventable in the scope of a cgroup hierarchy by allowing resource limiting
- * of the number of tasks in a cgroup.
- *
- * In order to use the `pids` controller, set the maximum number of tasks in
- * pids.max (this is not available in the root cgroup for obvious reasons). The
- * number of processes currently in the cgroup is given by pids.current.
- * Organisational operations are not blocked by cgroup policies, so it is
- * possible to have pids.current > pids.max. However, it is not possible to
- * violate a cgroup policy through fork(). fork() will return -EAGAIN if forking
- * would cause a cgroup policy to be violated.
- *
- * To set a cgroup to have no limit, set pids.max to "max". This is the default
- * for all new cgroups (N.B. that PID limits are hierarchical, so the most
- * stringent limit in the hierarchy is followed).
- *
- * pids.current tracks all child cgroup hierarchies, so parent/pids.current is
- * a superset of parent/child/pids.current.
- *
- * Copyright (C) 2015 Aleksa Sarai <cyphar@cyphar.com>
- *
- * This file is subject to the terms and conditions of version 2 of the GNU
- * General Public License. See the file COPYING in the main directory of the
- * Linux distribution for more details.
- */
-
-#include <linux/kernel.h>
-#include <linux/threads.h>
-#include <linux/atomic.h>
-#include <linux/cgroup.h>
-#include <linux/slab.h>
-
-#define PIDS_MAX (PID_MAX_LIMIT + 1ULL)
-#define PIDS_MAX_STR "max"
-
-struct pids_cgroup {
- struct cgroup_subsys_state css;
-
- /*
- * Use 64-bit types so that we can safely represent "max" as
- * %PIDS_MAX = (%PID_MAX_LIMIT + 1).
- */
- atomic64_t counter;
- int64_t limit;
-
- /* Handle for "pids.events" */
- struct cgroup_file events_file;
-
- /* Number of times fork failed because limit was hit. */
- atomic64_t events_limit;
-};
-
-static struct pids_cgroup *css_pids(struct cgroup_subsys_state *css)
-{
- return container_of(css, struct pids_cgroup, css);
-}
-
-static struct pids_cgroup *parent_pids(struct pids_cgroup *pids)
-{
- return css_pids(pids->css.parent);
-}
-
-static struct cgroup_subsys_state *
-pids_css_alloc(struct cgroup_subsys_state *parent)
-{
- struct pids_cgroup *pids;
-
- pids = kzalloc(sizeof(struct pids_cgroup), GFP_KERNEL);
- if (!pids)
- return ERR_PTR(-ENOMEM);
-
- pids->limit = PIDS_MAX;
- atomic64_set(&pids->counter, 0);
- atomic64_set(&pids->events_limit, 0);
- return &pids->css;
-}
-
-static void pids_css_free(struct cgroup_subsys_state *css)
-{
- kfree(css_pids(css));
-}
-
-/**
- * pids_cancel - uncharge the local pid count
- * @pids: the pid cgroup state
- * @num: the number of pids to cancel
- *
- * This function will WARN if the pid count goes under 0, because such a case is
- * a bug in the pids controller proper.
- */
-static void pids_cancel(struct pids_cgroup *pids, int num)
-{
- /*
- * A negative count (or overflow for that matter) is invalid,
- * and indicates a bug in the `pids` controller proper.
- */
- WARN_ON_ONCE(atomic64_add_negative(-num, &pids->counter));
-}
-
-/**
- * pids_uncharge - hierarchically uncharge the pid count
- * @pids: the pid cgroup state
- * @num: the number of pids to uncharge
- */
-static void pids_uncharge(struct pids_cgroup *pids, int num)
-{
- struct pids_cgroup *p;
-
- for (p = pids; parent_pids(p); p = parent_pids(p))
- pids_cancel(p, num);
-}
-
-/**
- * pids_charge - hierarchically charge the pid count
- * @pids: the pid cgroup state
- * @num: the number of pids to charge
- *
- * This function does *not* follow the pid limit set. It cannot fail and the new
- * pid count may exceed the limit. This is only used for reverting failed
- * attaches, where there is no other way out than violating the limit.
- */
-static void pids_charge(struct pids_cgroup *pids, int num)
-{
- struct pids_cgroup *p;
-
- for (p = pids; parent_pids(p); p = parent_pids(p))
- atomic64_add(num, &p->counter);
-}
-
-/**
- * pids_try_charge - hierarchically try to charge the pid count
- * @pids: the pid cgroup state
- * @num: the number of pids to charge
- *
- * This function follows the set limit. It will fail if the charge would cause
- * the new value to exceed the hierarchical limit. Returns 0 if the charge
- * succeeded, otherwise -EAGAIN.
- */
-static int pids_try_charge(struct pids_cgroup *pids, int num)
-{
- struct pids_cgroup *p, *q;
-
- for (p = pids; parent_pids(p); p = parent_pids(p)) {
- int64_t new = atomic64_add_return(num, &p->counter);
-
- /*
- * Since new is capped to the maximum number of pid_t, if
- * p->limit is %PIDS_MAX then we know that this test will never
- * fail.
- */
- if (new > p->limit)
- goto revert;
- }
-
- return 0;
-
-revert:
- for (q = pids; q != p; q = parent_pids(q))
- pids_cancel(q, num);
- pids_cancel(p, num);
-
- return -EAGAIN;
-}
-
-static int pids_can_attach(struct cgroup_taskset *tset)
-{
- struct task_struct *task;
- struct cgroup_subsys_state *dst_css;
-
- cgroup_taskset_for_each(task, dst_css, tset) {
- struct pids_cgroup *pids = css_pids(dst_css);
- struct cgroup_subsys_state *old_css;
- struct pids_cgroup *old_pids;
-
- /*
- * No need to pin @old_css between here and cancel_attach()
- * because cgroup core protects it from being freed before
- * the migration completes or fails.
- */
- old_css = task_css(task, pids_cgrp_id);
- old_pids = css_pids(old_css);
-
- pids_charge(pids, 1);
- pids_uncharge(old_pids, 1);
- }
-
- return 0;
-}
-
-static void pids_cancel_attach(struct cgroup_taskset *tset)
-{
- struct task_struct *task;
- struct cgroup_subsys_state *dst_css;
-
- cgroup_taskset_for_each(task, dst_css, tset) {
- struct pids_cgroup *pids = css_pids(dst_css);
- struct cgroup_subsys_state *old_css;
- struct pids_cgroup *old_pids;
-
- old_css = task_css(task, pids_cgrp_id);
- old_pids = css_pids(old_css);
-
- pids_charge(old_pids, 1);
- pids_uncharge(pids, 1);
- }
-}
-
-/*
- * task_css_check(true) in pids_can_fork() and pids_cancel_fork() relies
- * on threadgroup_change_begin() held by the copy_process().
- */
-static int pids_can_fork(struct task_struct *task)
-{
- struct cgroup_subsys_state *css;
- struct pids_cgroup *pids;
- int err;
-
- css = task_css_check(current, pids_cgrp_id, true);
- pids = css_pids(css);
- err = pids_try_charge(pids, 1);
- if (err) {
- /* Only log the first time events_limit is incremented. */
- if (atomic64_inc_return(&pids->events_limit) == 1) {
- pr_info("cgroup: fork rejected by pids controller in ");
- pr_cont_cgroup_path(task_cgroup(current, pids_cgrp_id));
- pr_cont("\n");
- }
- cgroup_file_notify(&pids->events_file);
- }
- return err;
-}
-
-static void pids_cancel_fork(struct task_struct *task)
-{
- struct cgroup_subsys_state *css;
- struct pids_cgroup *pids;
-
- css = task_css_check(current, pids_cgrp_id, true);
- pids = css_pids(css);
- pids_uncharge(pids, 1);
-}
-
-static void pids_free(struct task_struct *task)
-{
- struct pids_cgroup *pids = css_pids(task_css(task, pids_cgrp_id));
-
- pids_uncharge(pids, 1);
-}
-
-static ssize_t pids_max_write(struct kernfs_open_file *of, char *buf,
- size_t nbytes, loff_t off)
-{
- struct cgroup_subsys_state *css = of_css(of);
- struct pids_cgroup *pids = css_pids(css);
- int64_t limit;
- int err;
-
- buf = strstrip(buf);
- if (!strcmp(buf, PIDS_MAX_STR)) {
- limit = PIDS_MAX;
- goto set_limit;
- }
-
- err = kstrtoll(buf, 0, &limit);
- if (err)
- return err;
-
- if (limit < 0 || limit >= PIDS_MAX)
- return -EINVAL;
-
-set_limit:
- /*
- * Limit updates don't need to be mutex'd, since it isn't
- * critical that any racing fork()s follow the new limit.
- */
- pids->limit = limit;
- return nbytes;
-}
-
-static int pids_max_show(struct seq_file *sf, void *v)
-{
- struct cgroup_subsys_state *css = seq_css(sf);
- struct pids_cgroup *pids = css_pids(css);
- int64_t limit = pids->limit;
-
- if (limit >= PIDS_MAX)
- seq_printf(sf, "%s\n", PIDS_MAX_STR);
- else
- seq_printf(sf, "%lld\n", limit);
-
- return 0;
-}
-
-static s64 pids_current_read(struct cgroup_subsys_state *css,
- struct cftype *cft)
-{
- struct pids_cgroup *pids = css_pids(css);
-
- return atomic64_read(&pids->counter);
-}
-
-static int pids_events_show(struct seq_file *sf, void *v)
-{
- struct pids_cgroup *pids = css_pids(seq_css(sf));
-
- seq_printf(sf, "max %lld\n", (s64)atomic64_read(&pids->events_limit));
- return 0;
-}
-
-static struct cftype pids_files[] = {
- {
- .name = "max",
- .write = pids_max_write,
- .seq_show = pids_max_show,
- .flags = CFTYPE_NOT_ON_ROOT,
- },
- {
- .name = "current",
- .read_s64 = pids_current_read,
- .flags = CFTYPE_NOT_ON_ROOT,
- },
- {
- .name = "events",
- .seq_show = pids_events_show,
- .file_offset = offsetof(struct pids_cgroup, events_file),
- .flags = CFTYPE_NOT_ON_ROOT,
- },
- { } /* terminate */
-};
-
-struct cgroup_subsys pids_cgrp_subsys = {
- .css_alloc = pids_css_alloc,
- .css_free = pids_css_free,
- .can_attach = pids_can_attach,
- .cancel_attach = pids_cancel_attach,
- .can_fork = pids_can_fork,
- .cancel_fork = pids_cancel_fork,
- .free = pids_free,
- .legacy_cftypes = pids_files,
- .dfl_cftypes = pids_files,
-};
+++ /dev/null
-/*
- * kernel/cpuset.c
- *
- * Processor and Memory placement constraints for sets of tasks.
- *
- * Copyright (C) 2003 BULL SA.
- * Copyright (C) 2004-2007 Silicon Graphics, Inc.
- * Copyright (C) 2006 Google, Inc
- *
- * Portions derived from Patrick Mochel's sysfs code.
- * sysfs is Copyright (c) 2001-3 Patrick Mochel
- *
- * 2003-10-10 Written by Simon Derr.
- * 2003-10-22 Updates by Stephen Hemminger.
- * 2004 May-July Rework by Paul Jackson.
- * 2006 Rework by Paul Menage to use generic cgroups
- * 2008 Rework of the scheduler domains and CPU hotplug handling
- * by Max Krasnyansky
- *
- * This file is subject to the terms and conditions of the GNU General Public
- * License. See the file COPYING in the main directory of the Linux
- * distribution for more details.
- */
-
-#include <linux/cpu.h>
-#include <linux/cpumask.h>
-#include <linux/cpuset.h>
-#include <linux/err.h>
-#include <linux/errno.h>
-#include <linux/file.h>
-#include <linux/fs.h>
-#include <linux/init.h>
-#include <linux/interrupt.h>
-#include <linux/kernel.h>
-#include <linux/kmod.h>
-#include <linux/list.h>
-#include <linux/mempolicy.h>
-#include <linux/mm.h>
-#include <linux/memory.h>
-#include <linux/export.h>
-#include <linux/mount.h>
-#include <linux/namei.h>
-#include <linux/pagemap.h>
-#include <linux/proc_fs.h>
-#include <linux/rcupdate.h>
-#include <linux/sched.h>
-#include <linux/seq_file.h>
-#include <linux/security.h>
-#include <linux/slab.h>
-#include <linux/spinlock.h>
-#include <linux/stat.h>
-#include <linux/string.h>
-#include <linux/time.h>
-#include <linux/time64.h>
-#include <linux/backing-dev.h>
-#include <linux/sort.h>
-
-#include <linux/uaccess.h>
-#include <linux/atomic.h>
-#include <linux/mutex.h>
-#include <linux/cgroup.h>
-#include <linux/wait.h>
-
-DEFINE_STATIC_KEY_FALSE(cpusets_enabled_key);
-
-/* See "Frequency meter" comments, below. */
-
-struct fmeter {
- int cnt; /* unprocessed events count */
- int val; /* most recent output value */
- time64_t time; /* clock (secs) when val computed */
- spinlock_t lock; /* guards read or write of above */
-};
-
-struct cpuset {
- struct cgroup_subsys_state css;
-
- unsigned long flags; /* "unsigned long" so bitops work */
-
- /*
- * On default hierarchy:
- *
- * The user-configured masks can only be changed by writing to
- * cpuset.cpus and cpuset.mems, and won't be limited by the
- * parent masks.
- *
- * The effective masks is the real masks that apply to the tasks
- * in the cpuset. They may be changed if the configured masks are
- * changed or hotplug happens.
- *
- * effective_mask == configured_mask & parent's effective_mask,
- * and if it ends up empty, it will inherit the parent's mask.
- *
- *
- * On legacy hierachy:
- *
- * The user-configured masks are always the same with effective masks.
- */
-
- /* user-configured CPUs and Memory Nodes allow to tasks */
- cpumask_var_t cpus_allowed;
- nodemask_t mems_allowed;
-
- /* effective CPUs and Memory Nodes allow to tasks */
- cpumask_var_t effective_cpus;
- nodemask_t effective_mems;
-
- /*
- * This is old Memory Nodes tasks took on.
- *
- * - top_cpuset.old_mems_allowed is initialized to mems_allowed.
- * - A new cpuset's old_mems_allowed is initialized when some
- * task is moved into it.
- * - old_mems_allowed is used in cpuset_migrate_mm() when we change
- * cpuset.mems_allowed and have tasks' nodemask updated, and
- * then old_mems_allowed is updated to mems_allowed.
- */
- nodemask_t old_mems_allowed;
-
- struct fmeter fmeter; /* memory_pressure filter */
-
- /*
- * Tasks are being attached to this cpuset. Used to prevent
- * zeroing cpus/mems_allowed between ->can_attach() and ->attach().
- */
- int attach_in_progress;
-
- /* partition number for rebuild_sched_domains() */
- int pn;
-
- /* for custom sched domain */
- int relax_domain_level;
-};
-
-static inline struct cpuset *css_cs(struct cgroup_subsys_state *css)
-{
- return css ? container_of(css, struct cpuset, css) : NULL;
-}
-
-/* Retrieve the cpuset for a task */
-static inline struct cpuset *task_cs(struct task_struct *task)
-{
- return css_cs(task_css(task, cpuset_cgrp_id));
-}
-
-static inline struct cpuset *parent_cs(struct cpuset *cs)
-{
- return css_cs(cs->css.parent);
-}
-
-#ifdef CONFIG_NUMA
-static inline bool task_has_mempolicy(struct task_struct *task)
-{
- return task->mempolicy;
-}
-#else
-static inline bool task_has_mempolicy(struct task_struct *task)
-{
- return false;
-}
-#endif
-
-
-/* bits in struct cpuset flags field */
-typedef enum {
- CS_ONLINE,
- CS_CPU_EXCLUSIVE,
- CS_MEM_EXCLUSIVE,
- CS_MEM_HARDWALL,
- CS_MEMORY_MIGRATE,
- CS_SCHED_LOAD_BALANCE,
- CS_SPREAD_PAGE,
- CS_SPREAD_SLAB,
-} cpuset_flagbits_t;
-
-/* convenient tests for these bits */
-static inline bool is_cpuset_online(const struct cpuset *cs)
-{
- return test_bit(CS_ONLINE, &cs->flags);
-}
-
-static inline int is_cpu_exclusive(const struct cpuset *cs)
-{
- return test_bit(CS_CPU_EXCLUSIVE, &cs->flags);
-}
-
-static inline int is_mem_exclusive(const struct cpuset *cs)
-{
- return test_bit(CS_MEM_EXCLUSIVE, &cs->flags);
-}
-
-static inline int is_mem_hardwall(const struct cpuset *cs)
-{
- return test_bit(CS_MEM_HARDWALL, &cs->flags);
-}
-
-static inline int is_sched_load_balance(const struct cpuset *cs)
-{
- return test_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
-}
-
-static inline int is_memory_migrate(const struct cpuset *cs)
-{
- return test_bit(CS_MEMORY_MIGRATE, &cs->flags);
-}
-
-static inline int is_spread_page(const struct cpuset *cs)
-{
- return test_bit(CS_SPREAD_PAGE, &cs->flags);
-}
-
-static inline int is_spread_slab(const struct cpuset *cs)
-{
- return test_bit(CS_SPREAD_SLAB, &cs->flags);
-}
-
-static struct cpuset top_cpuset = {
- .flags = ((1 << CS_ONLINE) | (1 << CS_CPU_EXCLUSIVE) |
- (1 << CS_MEM_EXCLUSIVE)),
-};
-
-/**
- * cpuset_for_each_child - traverse online children of a cpuset
- * @child_cs: loop cursor pointing to the current child
- * @pos_css: used for iteration
- * @parent_cs: target cpuset to walk children of
- *
- * Walk @child_cs through the online children of @parent_cs. Must be used
- * with RCU read locked.
- */
-#define cpuset_for_each_child(child_cs, pos_css, parent_cs) \
- css_for_each_child((pos_css), &(parent_cs)->css) \
- if (is_cpuset_online(((child_cs) = css_cs((pos_css)))))
-
-/**
- * cpuset_for_each_descendant_pre - pre-order walk of a cpuset's descendants
- * @des_cs: loop cursor pointing to the current descendant
- * @pos_css: used for iteration
- * @root_cs: target cpuset to walk ancestor of
- *
- * Walk @des_cs through the online descendants of @root_cs. Must be used
- * with RCU read locked. The caller may modify @pos_css by calling
- * css_rightmost_descendant() to skip subtree. @root_cs is included in the
- * iteration and the first node to be visited.
- */
-#define cpuset_for_each_descendant_pre(des_cs, pos_css, root_cs) \
- css_for_each_descendant_pre((pos_css), &(root_cs)->css) \
- if (is_cpuset_online(((des_cs) = css_cs((pos_css)))))
-
-/*
- * There are two global locks guarding cpuset structures - cpuset_mutex and
- * callback_lock. We also require taking task_lock() when dereferencing a
- * task's cpuset pointer. See "The task_lock() exception", at the end of this
- * comment.
- *
- * A task must hold both locks to modify cpusets. If a task holds
- * cpuset_mutex, then it blocks others wanting that mutex, ensuring that it
- * is the only task able to also acquire callback_lock and be able to
- * modify cpusets. It can perform various checks on the cpuset structure
- * first, knowing nothing will change. It can also allocate memory while
- * just holding cpuset_mutex. While it is performing these checks, various
- * callback routines can briefly acquire callback_lock to query cpusets.
- * Once it is ready to make the changes, it takes callback_lock, blocking
- * everyone else.
- *
- * Calls to the kernel memory allocator can not be made while holding
- * callback_lock, as that would risk double tripping on callback_lock
- * from one of the callbacks into the cpuset code from within
- * __alloc_pages().
- *
- * If a task is only holding callback_lock, then it has read-only
- * access to cpusets.
- *
- * Now, the task_struct fields mems_allowed and mempolicy may be changed
- * by other task, we use alloc_lock in the task_struct fields to protect
- * them.
- *
- * The cpuset_common_file_read() handlers only hold callback_lock across
- * small pieces of code, such as when reading out possibly multi-word
- * cpumasks and nodemasks.
- *
- * Accessing a task's cpuset should be done in accordance with the
- * guidelines for accessing subsystem state in kernel/cgroup.c
- */
-
-static DEFINE_MUTEX(cpuset_mutex);
-static DEFINE_SPINLOCK(callback_lock);
-
-static struct workqueue_struct *cpuset_migrate_mm_wq;
-
-/*
- * CPU / memory hotplug is handled asynchronously.
- */
-static void cpuset_hotplug_workfn(struct work_struct *work);
-static DECLARE_WORK(cpuset_hotplug_work, cpuset_hotplug_workfn);
-
-static DECLARE_WAIT_QUEUE_HEAD(cpuset_attach_wq);
-
-/*
- * This is ugly, but preserves the userspace API for existing cpuset
- * users. If someone tries to mount the "cpuset" filesystem, we
- * silently switch it to mount "cgroup" instead
- */
-static struct dentry *cpuset_mount(struct file_system_type *fs_type,
- int flags, const char *unused_dev_name, void *data)
-{
- struct file_system_type *cgroup_fs = get_fs_type("cgroup");
- struct dentry *ret = ERR_PTR(-ENODEV);
- if (cgroup_fs) {
- char mountopts[] =
- "cpuset,noprefix,"
- "release_agent=/sbin/cpuset_release_agent";
- ret = cgroup_fs->mount(cgroup_fs, flags,
- unused_dev_name, mountopts);
- put_filesystem(cgroup_fs);
- }
- return ret;
-}
-
-static struct file_system_type cpuset_fs_type = {
- .name = "cpuset",
- .mount = cpuset_mount,
-};
-
-/*
- * Return in pmask the portion of a cpusets's cpus_allowed that
- * are online. If none are online, walk up the cpuset hierarchy
- * until we find one that does have some online cpus.
- *
- * One way or another, we guarantee to return some non-empty subset
- * of cpu_online_mask.
- *
- * Call with callback_lock or cpuset_mutex held.
- */
-static void guarantee_online_cpus(struct cpuset *cs, struct cpumask *pmask)
-{
- while (!cpumask_intersects(cs->effective_cpus, cpu_online_mask)) {
- cs = parent_cs(cs);
- if (unlikely(!cs)) {
- /*
- * The top cpuset doesn't have any online cpu as a
- * consequence of a race between cpuset_hotplug_work
- * and cpu hotplug notifier. But we know the top
- * cpuset's effective_cpus is on its way to to be
- * identical to cpu_online_mask.
- */
- cpumask_copy(pmask, cpu_online_mask);
- return;
- }
- }
- cpumask_and(pmask, cs->effective_cpus, cpu_online_mask);
-}
-
-/*
- * Return in *pmask the portion of a cpusets's mems_allowed that
- * are online, with memory. If none are online with memory, walk
- * up the cpuset hierarchy until we find one that does have some
- * online mems. The top cpuset always has some mems online.
- *
- * One way or another, we guarantee to return some non-empty subset
- * of node_states[N_MEMORY].
- *
- * Call with callback_lock or cpuset_mutex held.
- */
-static void guarantee_online_mems(struct cpuset *cs, nodemask_t *pmask)
-{
- while (!nodes_intersects(cs->effective_mems, node_states[N_MEMORY]))
- cs = parent_cs(cs);
- nodes_and(*pmask, cs->effective_mems, node_states[N_MEMORY]);
-}
-
-/*
- * update task's spread flag if cpuset's page/slab spread flag is set
- *
- * Call with callback_lock or cpuset_mutex held.
- */
-static void cpuset_update_task_spread_flag(struct cpuset *cs,
- struct task_struct *tsk)
-{
- if (is_spread_page(cs))
- task_set_spread_page(tsk);
- else
- task_clear_spread_page(tsk);
-
- if (is_spread_slab(cs))
- task_set_spread_slab(tsk);
- else
- task_clear_spread_slab(tsk);
-}
-
-/*
- * is_cpuset_subset(p, q) - Is cpuset p a subset of cpuset q?
- *
- * One cpuset is a subset of another if all its allowed CPUs and
- * Memory Nodes are a subset of the other, and its exclusive flags
- * are only set if the other's are set. Call holding cpuset_mutex.
- */
-
-static int is_cpuset_subset(const struct cpuset *p, const struct cpuset *q)
-{
- return cpumask_subset(p->cpus_allowed, q->cpus_allowed) &&
- nodes_subset(p->mems_allowed, q->mems_allowed) &&
- is_cpu_exclusive(p) <= is_cpu_exclusive(q) &&
- is_mem_exclusive(p) <= is_mem_exclusive(q);
-}
-
-/**
- * alloc_trial_cpuset - allocate a trial cpuset
- * @cs: the cpuset that the trial cpuset duplicates
- */
-static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
-{
- struct cpuset *trial;
-
- trial = kmemdup(cs, sizeof(*cs), GFP_KERNEL);
- if (!trial)
- return NULL;
-
- if (!alloc_cpumask_var(&trial->cpus_allowed, GFP_KERNEL))
- goto free_cs;
- if (!alloc_cpumask_var(&trial->effective_cpus, GFP_KERNEL))
- goto free_cpus;
-
- cpumask_copy(trial->cpus_allowed, cs->cpus_allowed);
- cpumask_copy(trial->effective_cpus, cs->effective_cpus);
- return trial;
-
-free_cpus:
- free_cpumask_var(trial->cpus_allowed);
-free_cs:
- kfree(trial);
- return NULL;
-}
-
-/**
- * free_trial_cpuset - free the trial cpuset
- * @trial: the trial cpuset to be freed
- */
-static void free_trial_cpuset(struct cpuset *trial)
-{
- free_cpumask_var(trial->effective_cpus);
- free_cpumask_var(trial->cpus_allowed);
- kfree(trial);
-}
-
-/*
- * validate_change() - Used to validate that any proposed cpuset change
- * follows the structural rules for cpusets.
- *
- * If we replaced the flag and mask values of the current cpuset
- * (cur) with those values in the trial cpuset (trial), would
- * our various subset and exclusive rules still be valid? Presumes
- * cpuset_mutex held.
- *
- * 'cur' is the address of an actual, in-use cpuset. Operations
- * such as list traversal that depend on the actual address of the
- * cpuset in the list must use cur below, not trial.
- *
- * 'trial' is the address of bulk structure copy of cur, with
- * perhaps one or more of the fields cpus_allowed, mems_allowed,
- * or flags changed to new, trial values.
- *
- * Return 0 if valid, -errno if not.
- */
-
-static int validate_change(struct cpuset *cur, struct cpuset *trial)
-{
- struct cgroup_subsys_state *css;
- struct cpuset *c, *par;
- int ret;
-
- rcu_read_lock();
-
- /* Each of our child cpusets must be a subset of us */
- ret = -EBUSY;
- cpuset_for_each_child(c, css, cur)
- if (!is_cpuset_subset(c, trial))
- goto out;
-
- /* Remaining checks don't apply to root cpuset */
- ret = 0;
- if (cur == &top_cpuset)
- goto out;
-
- par = parent_cs(cur);
-
- /* On legacy hiearchy, we must be a subset of our parent cpuset. */
- ret = -EACCES;
- if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
- !is_cpuset_subset(trial, par))
- goto out;
-
- /*
- * If either I or some sibling (!= me) is exclusive, we can't
- * overlap
- */
- ret = -EINVAL;
- cpuset_for_each_child(c, css, par) {
- if ((is_cpu_exclusive(trial) || is_cpu_exclusive(c)) &&
- c != cur &&
- cpumask_intersects(trial->cpus_allowed, c->cpus_allowed))
- goto out;
- if ((is_mem_exclusive(trial) || is_mem_exclusive(c)) &&
- c != cur &&
- nodes_intersects(trial->mems_allowed, c->mems_allowed))
- goto out;
- }
-
- /*
- * Cpusets with tasks - existing or newly being attached - can't
- * be changed to have empty cpus_allowed or mems_allowed.
- */
- ret = -ENOSPC;
- if ((cgroup_is_populated(cur->css.cgroup) || cur->attach_in_progress)) {
- if (!cpumask_empty(cur->cpus_allowed) &&
- cpumask_empty(trial->cpus_allowed))
- goto out;
- if (!nodes_empty(cur->mems_allowed) &&
- nodes_empty(trial->mems_allowed))
- goto out;
- }
-
- /*
- * We can't shrink if we won't have enough room for SCHED_DEADLINE
- * tasks.
- */
- ret = -EBUSY;
- if (is_cpu_exclusive(cur) &&
- !cpuset_cpumask_can_shrink(cur->cpus_allowed,
- trial->cpus_allowed))
- goto out;
-
- ret = 0;
-out:
- rcu_read_unlock();
- return ret;
-}
-
-#ifdef CONFIG_SMP
-/*
- * Helper routine for generate_sched_domains().
- * Do cpusets a, b have overlapping effective cpus_allowed masks?
- */
-static int cpusets_overlap(struct cpuset *a, struct cpuset *b)
-{
- return cpumask_intersects(a->effective_cpus, b->effective_cpus);
-}
-
-static void
-update_domain_attr(struct sched_domain_attr *dattr, struct cpuset *c)
-{
- if (dattr->relax_domain_level < c->relax_domain_level)
- dattr->relax_domain_level = c->relax_domain_level;
- return;
-}
-
-static void update_domain_attr_tree(struct sched_domain_attr *dattr,
- struct cpuset *root_cs)
-{
- struct cpuset *cp;
- struct cgroup_subsys_state *pos_css;
-
- rcu_read_lock();
- cpuset_for_each_descendant_pre(cp, pos_css, root_cs) {
- /* skip the whole subtree if @cp doesn't have any CPU */
- if (cpumask_empty(cp->cpus_allowed)) {
- pos_css = css_rightmost_descendant(pos_css);
- continue;
- }
-
- if (is_sched_load_balance(cp))
- update_domain_attr(dattr, cp);
- }
- rcu_read_unlock();
-}
-
-/*
- * generate_sched_domains()
- *
- * This function builds a partial partition of the systems CPUs
- * A 'partial partition' is a set of non-overlapping subsets whose
- * union is a subset of that set.
- * The output of this function needs to be passed to kernel/sched/core.c
- * partition_sched_domains() routine, which will rebuild the scheduler's
- * load balancing domains (sched domains) as specified by that partial
- * partition.
- *
- * See "What is sched_load_balance" in Documentation/cgroups/cpusets.txt
- * for a background explanation of this.
- *
- * Does not return errors, on the theory that the callers of this
- * routine would rather not worry about failures to rebuild sched
- * domains when operating in the severe memory shortage situations
- * that could cause allocation failures below.
- *
- * Must be called with cpuset_mutex held.
- *
- * The three key local variables below are:
- * q - a linked-list queue of cpuset pointers, used to implement a
- * top-down scan of all cpusets. This scan loads a pointer
- * to each cpuset marked is_sched_load_balance into the
- * array 'csa'. For our purposes, rebuilding the schedulers
- * sched domains, we can ignore !is_sched_load_balance cpusets.
- * csa - (for CpuSet Array) Array of pointers to all the cpusets
- * that need to be load balanced, for convenient iterative
- * access by the subsequent code that finds the best partition,
- * i.e the set of domains (subsets) of CPUs such that the
- * cpus_allowed of every cpuset marked is_sched_load_balance
- * is a subset of one of these domains, while there are as
- * many such domains as possible, each as small as possible.
- * doms - Conversion of 'csa' to an array of cpumasks, for passing to
- * the kernel/sched/core.c routine partition_sched_domains() in a
- * convenient format, that can be easily compared to the prior
- * value to determine what partition elements (sched domains)
- * were changed (added or removed.)
- *
- * Finding the best partition (set of domains):
- * The triple nested loops below over i, j, k scan over the
- * load balanced cpusets (using the array of cpuset pointers in
- * csa[]) looking for pairs of cpusets that have overlapping
- * cpus_allowed, but which don't have the same 'pn' partition
- * number and gives them in the same partition number. It keeps
- * looping on the 'restart' label until it can no longer find
- * any such pairs.
- *
- * The union of the cpus_allowed masks from the set of
- * all cpusets having the same 'pn' value then form the one
- * element of the partition (one sched domain) to be passed to
- * partition_sched_domains().
- */
-static int generate_sched_domains(cpumask_var_t **domains,
- struct sched_domain_attr **attributes)
-{
- struct cpuset *cp; /* scans q */
- struct cpuset **csa; /* array of all cpuset ptrs */
- int csn; /* how many cpuset ptrs in csa so far */
- int i, j, k; /* indices for partition finding loops */
- cpumask_var_t *doms; /* resulting partition; i.e. sched domains */
- cpumask_var_t non_isolated_cpus; /* load balanced CPUs */
- struct sched_domain_attr *dattr; /* attributes for custom domains */
- int ndoms = 0; /* number of sched domains in result */
- int nslot; /* next empty doms[] struct cpumask slot */
- struct cgroup_subsys_state *pos_css;
-
- doms = NULL;
- dattr = NULL;
- csa = NULL;
-
- if (!alloc_cpumask_var(&non_isolated_cpus, GFP_KERNEL))
- goto done;
- cpumask_andnot(non_isolated_cpus, cpu_possible_mask, cpu_isolated_map);
-
- /* Special case for the 99% of systems with one, full, sched domain */
- if (is_sched_load_balance(&top_cpuset)) {
- ndoms = 1;
- doms = alloc_sched_domains(ndoms);
- if (!doms)
- goto done;
-
- dattr = kmalloc(sizeof(struct sched_domain_attr), GFP_KERNEL);
- if (dattr) {
- *dattr = SD_ATTR_INIT;
- update_domain_attr_tree(dattr, &top_cpuset);
- }
- cpumask_and(doms[0], top_cpuset.effective_cpus,
- non_isolated_cpus);
-
- goto done;
- }
-
- csa = kmalloc(nr_cpusets() * sizeof(cp), GFP_KERNEL);
- if (!csa)
- goto done;
- csn = 0;
-
- rcu_read_lock();
- cpuset_for_each_descendant_pre(cp, pos_css, &top_cpuset) {
- if (cp == &top_cpuset)
- continue;
- /*
- * Continue traversing beyond @cp iff @cp has some CPUs and
- * isn't load balancing. The former is obvious. The
- * latter: All child cpusets contain a subset of the
- * parent's cpus, so just skip them, and then we call
- * update_domain_attr_tree() to calc relax_domain_level of
- * the corresponding sched domain.
- */
- if (!cpumask_empty(cp->cpus_allowed) &&
- !(is_sched_load_balance(cp) &&
- cpumask_intersects(cp->cpus_allowed, non_isolated_cpus)))
- continue;
-
- if (is_sched_load_balance(cp))
- csa[csn++] = cp;
-
- /* skip @cp's subtree */
- pos_css = css_rightmost_descendant(pos_css);
- }
- rcu_read_unlock();
-
- for (i = 0; i < csn; i++)
- csa[i]->pn = i;
- ndoms = csn;
-
-restart:
- /* Find the best partition (set of sched domains) */
- for (i = 0; i < csn; i++) {
- struct cpuset *a = csa[i];
- int apn = a->pn;
-
- for (j = 0; j < csn; j++) {
- struct cpuset *b = csa[j];
- int bpn = b->pn;
-
- if (apn != bpn && cpusets_overlap(a, b)) {
- for (k = 0; k < csn; k++) {
- struct cpuset *c = csa[k];
-
- if (c->pn == bpn)
- c->pn = apn;
- }
- ndoms--; /* one less element */
- goto restart;
- }
- }
- }
-
- /*
- * Now we know how many domains to create.
- * Convert <csn, csa> to <ndoms, doms> and populate cpu masks.
- */
- doms = alloc_sched_domains(ndoms);
- if (!doms)
- goto done;
-
- /*
- * The rest of the code, including the scheduler, can deal with
- * dattr==NULL case. No need to abort if alloc fails.
- */
- dattr = kmalloc(ndoms * sizeof(struct sched_domain_attr), GFP_KERNEL);
-
- for (nslot = 0, i = 0; i < csn; i++) {
- struct cpuset *a = csa[i];
- struct cpumask *dp;
- int apn = a->pn;
-
- if (apn < 0) {
- /* Skip completed partitions */
- continue;
- }
-
- dp = doms[nslot];
-
- if (nslot == ndoms) {
- static int warnings = 10;
- if (warnings) {
- pr_warn("rebuild_sched_domains confused: nslot %d, ndoms %d, csn %d, i %d, apn %d\n",
- nslot, ndoms, csn, i, apn);
- warnings--;
- }
- continue;
- }
-
- cpumask_clear(dp);
- if (dattr)
- *(dattr + nslot) = SD_ATTR_INIT;
- for (j = i; j < csn; j++) {
- struct cpuset *b = csa[j];
-
- if (apn == b->pn) {
- cpumask_or(dp, dp, b->effective_cpus);
- cpumask_and(dp, dp, non_isolated_cpus);
- if (dattr)
- update_domain_attr_tree(dattr + nslot, b);
-
- /* Done with this partition */
- b->pn = -1;
- }
- }
- nslot++;
- }
- BUG_ON(nslot != ndoms);
-
-done:
- free_cpumask_var(non_isolated_cpus);
- kfree(csa);
-
- /*
- * Fallback to the default domain if kmalloc() failed.
- * See comments in partition_sched_domains().
- */
- if (doms == NULL)
- ndoms = 1;
-
- *domains = doms;
- *attributes = dattr;
- return ndoms;
-}
-
-/*
- * Rebuild scheduler domains.
- *
- * If the flag 'sched_load_balance' of any cpuset with non-empty
- * 'cpus' changes, or if the 'cpus' allowed changes in any cpuset
- * which has that flag enabled, or if any cpuset with a non-empty
- * 'cpus' is removed, then call this routine to rebuild the
- * scheduler's dynamic sched domains.
- *
- * Call with cpuset_mutex held. Takes get_online_cpus().
- */
-static void rebuild_sched_domains_locked(void)
-{
- struct sched_domain_attr *attr;
- cpumask_var_t *doms;
- int ndoms;
-
- lockdep_assert_held(&cpuset_mutex);
- get_online_cpus();
-
- /*
- * We have raced with CPU hotplug. Don't do anything to avoid
- * passing doms with offlined cpu to partition_sched_domains().
- * Anyways, hotplug work item will rebuild sched domains.
- */
- if (!cpumask_equal(top_cpuset.effective_cpus, cpu_active_mask))
- goto out;
-
- /* Generate domain masks and attrs */
- ndoms = generate_sched_domains(&doms, &attr);
-
- /* Have scheduler rebuild the domains */
- partition_sched_domains(ndoms, doms, attr);
-out:
- put_online_cpus();
-}
-#else /* !CONFIG_SMP */
-static void rebuild_sched_domains_locked(void)
-{
-}
-#endif /* CONFIG_SMP */
-
-void rebuild_sched_domains(void)
-{
- mutex_lock(&cpuset_mutex);
- rebuild_sched_domains_locked();
- mutex_unlock(&cpuset_mutex);
-}
-
-/**
- * update_tasks_cpumask - Update the cpumasks of tasks in the cpuset.
- * @cs: the cpuset in which each task's cpus_allowed mask needs to be changed
- *
- * Iterate through each task of @cs updating its cpus_allowed to the
- * effective cpuset's. As this function is called with cpuset_mutex held,
- * cpuset membership stays stable.
- */
-static void update_tasks_cpumask(struct cpuset *cs)
-{
- struct css_task_iter it;
- struct task_struct *task;
-
- css_task_iter_start(&cs->css, &it);
- while ((task = css_task_iter_next(&it)))
- set_cpus_allowed_ptr(task, cs->effective_cpus);
- css_task_iter_end(&it);
-}
-
-/*
- * update_cpumasks_hier - Update effective cpumasks and tasks in the subtree
- * @cs: the cpuset to consider
- * @new_cpus: temp variable for calculating new effective_cpus
- *
- * When congifured cpumask is changed, the effective cpumasks of this cpuset
- * and all its descendants need to be updated.
- *
- * On legacy hierachy, effective_cpus will be the same with cpu_allowed.
- *
- * Called with cpuset_mutex held
- */
-static void update_cpumasks_hier(struct cpuset *cs, struct cpumask *new_cpus)
-{
- struct cpuset *cp;
- struct cgroup_subsys_state *pos_css;
- bool need_rebuild_sched_domains = false;
-
- rcu_read_lock();
- cpuset_for_each_descendant_pre(cp, pos_css, cs) {
- struct cpuset *parent = parent_cs(cp);
-
- cpumask_and(new_cpus, cp->cpus_allowed, parent->effective_cpus);
-
- /*
- * If it becomes empty, inherit the effective mask of the
- * parent, which is guaranteed to have some CPUs.
- */
- if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
- cpumask_empty(new_cpus))
- cpumask_copy(new_cpus, parent->effective_cpus);
-
- /* Skip the whole subtree if the cpumask remains the same. */
- if (cpumask_equal(new_cpus, cp->effective_cpus)) {
- pos_css = css_rightmost_descendant(pos_css);
- continue;
- }
-
- if (!css_tryget_online(&cp->css))
- continue;
- rcu_read_unlock();
-
- spin_lock_irq(&callback_lock);
- cpumask_copy(cp->effective_cpus, new_cpus);
- spin_unlock_irq(&callback_lock);
-
- WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
- !cpumask_equal(cp->cpus_allowed, cp->effective_cpus));
-
- update_tasks_cpumask(cp);
-
- /*
- * If the effective cpumask of any non-empty cpuset is changed,
- * we need to rebuild sched domains.
- */
- if (!cpumask_empty(cp->cpus_allowed) &&
- is_sched_load_balance(cp))
- need_rebuild_sched_domains = true;
-
- rcu_read_lock();
- css_put(&cp->css);
- }
- rcu_read_unlock();
-
- if (need_rebuild_sched_domains)
- rebuild_sched_domains_locked();
-}
-
-/**
- * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
- * @cs: the cpuset to consider
- * @trialcs: trial cpuset
- * @buf: buffer of cpu numbers written to this cpuset
- */
-static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
- const char *buf)
-{
- int retval;
-
- /* top_cpuset.cpus_allowed tracks cpu_online_mask; it's read-only */
- if (cs == &top_cpuset)
- return -EACCES;
-
- /*
- * An empty cpus_allowed is ok only if the cpuset has no tasks.
- * Since cpulist_parse() fails on an empty mask, we special case
- * that parsing. The validate_change() call ensures that cpusets
- * with tasks have cpus.
- */
- if (!*buf) {
- cpumask_clear(trialcs->cpus_allowed);
- } else {
- retval = cpulist_parse(buf, trialcs->cpus_allowed);
- if (retval < 0)
- return retval;
-
- if (!cpumask_subset(trialcs->cpus_allowed,
- top_cpuset.cpus_allowed))
- return -EINVAL;
- }
-
- /* Nothing to do if the cpus didn't change */
- if (cpumask_equal(cs->cpus_allowed, trialcs->cpus_allowed))
- return 0;
-
- retval = validate_change(cs, trialcs);
- if (retval < 0)
- return retval;
-
- spin_lock_irq(&callback_lock);
- cpumask_copy(cs->cpus_allowed, trialcs->cpus_allowed);
- spin_unlock_irq(&callback_lock);
-
- /* use trialcs->cpus_allowed as a temp variable */
- update_cpumasks_hier(cs, trialcs->cpus_allowed);
- return 0;
-}
-
-/*
- * Migrate memory region from one set of nodes to another. This is
- * performed asynchronously as it can be called from process migration path
- * holding locks involved in process management. All mm migrations are
- * performed in the queued order and can be waited for by flushing
- * cpuset_migrate_mm_wq.
- */
-
-struct cpuset_migrate_mm_work {
- struct work_struct work;
- struct mm_struct *mm;
- nodemask_t from;
- nodemask_t to;
-};
-
-static void cpuset_migrate_mm_workfn(struct work_struct *work)
-{
- struct cpuset_migrate_mm_work *mwork =
- container_of(work, struct cpuset_migrate_mm_work, work);
-
- /* on a wq worker, no need to worry about %current's mems_allowed */
- do_migrate_pages(mwork->mm, &mwork->from, &mwork->to, MPOL_MF_MOVE_ALL);
- mmput(mwork->mm);
- kfree(mwork);
-}
-
-static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
- const nodemask_t *to)
-{
- struct cpuset_migrate_mm_work *mwork;
-
- mwork = kzalloc(sizeof(*mwork), GFP_KERNEL);
- if (mwork) {
- mwork->mm = mm;
- mwork->from = *from;
- mwork->to = *to;
- INIT_WORK(&mwork->work, cpuset_migrate_mm_workfn);
- queue_work(cpuset_migrate_mm_wq, &mwork->work);
- } else {
- mmput(mm);
- }
-}
-
-static void cpuset_post_attach(void)
-{
- flush_workqueue(cpuset_migrate_mm_wq);
-}
-
-/*
- * cpuset_change_task_nodemask - change task's mems_allowed and mempolicy
- * @tsk: the task to change
- * @newmems: new nodes that the task will be set
- *
- * In order to avoid seeing no nodes if the old and new nodes are disjoint,
- * we structure updates as setting all new allowed nodes, then clearing newly
- * disallowed ones.
- */
-static void cpuset_change_task_nodemask(struct task_struct *tsk,
- nodemask_t *newmems)
-{
- bool need_loop;
-
- task_lock(tsk);
- /*
- * Determine if a loop is necessary if another thread is doing
- * read_mems_allowed_begin(). If at least one node remains unchanged and
- * tsk does not have a mempolicy, then an empty nodemask will not be
- * possible when mems_allowed is larger than a word.
- */
- need_loop = task_has_mempolicy(tsk) ||
- !nodes_intersects(*newmems, tsk->mems_allowed);
-
- if (need_loop) {
- local_irq_disable();
- write_seqcount_begin(&tsk->mems_allowed_seq);
- }
-
- nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
- mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
-
- mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
- tsk->mems_allowed = *newmems;
-
- if (need_loop) {
- write_seqcount_end(&tsk->mems_allowed_seq);
- local_irq_enable();
- }
-
- task_unlock(tsk);
-}
-
-static void *cpuset_being_rebound;
-
-/**
- * update_tasks_nodemask - Update the nodemasks of tasks in the cpuset.
- * @cs: the cpuset in which each task's mems_allowed mask needs to be changed
- *
- * Iterate through each task of @cs updating its mems_allowed to the
- * effective cpuset's. As this function is called with cpuset_mutex held,
- * cpuset membership stays stable.
- */
-static void update_tasks_nodemask(struct cpuset *cs)
-{
- static nodemask_t newmems; /* protected by cpuset_mutex */
- struct css_task_iter it;
- struct task_struct *task;
-
- cpuset_being_rebound = cs; /* causes mpol_dup() rebind */
-
- guarantee_online_mems(cs, &newmems);
-
- /*
- * The mpol_rebind_mm() call takes mmap_sem, which we couldn't
- * take while holding tasklist_lock. Forks can happen - the
- * mpol_dup() cpuset_being_rebound check will catch such forks,
- * and rebind their vma mempolicies too. Because we still hold
- * the global cpuset_mutex, we know that no other rebind effort
- * will be contending for the global variable cpuset_being_rebound.
- * It's ok if we rebind the same mm twice; mpol_rebind_mm()
- * is idempotent. Also migrate pages in each mm to new nodes.
- */
- css_task_iter_start(&cs->css, &it);
- while ((task = css_task_iter_next(&it))) {
- struct mm_struct *mm;
- bool migrate;
-
- cpuset_change_task_nodemask(task, &newmems);
-
- mm = get_task_mm(task);
- if (!mm)
- continue;
-
- migrate = is_memory_migrate(cs);
-
- mpol_rebind_mm(mm, &cs->mems_allowed);
- if (migrate)
- cpuset_migrate_mm(mm, &cs->old_mems_allowed, &newmems);
- else
- mmput(mm);
- }
- css_task_iter_end(&it);
-
- /*
- * All the tasks' nodemasks have been updated, update
- * cs->old_mems_allowed.
- */
- cs->old_mems_allowed = newmems;
-
- /* We're done rebinding vmas to this cpuset's new mems_allowed. */
- cpuset_being_rebound = NULL;
-}
-
-/*
- * update_nodemasks_hier - Update effective nodemasks and tasks in the subtree
- * @cs: the cpuset to consider
- * @new_mems: a temp variable for calculating new effective_mems
- *
- * When configured nodemask is changed, the effective nodemasks of this cpuset
- * and all its descendants need to be updated.
- *
- * On legacy hiearchy, effective_mems will be the same with mems_allowed.
- *
- * Called with cpuset_mutex held
- */
-static void update_nodemasks_hier(struct cpuset *cs, nodemask_t *new_mems)
-{
- struct cpuset *cp;
- struct cgroup_subsys_state *pos_css;
-
- rcu_read_lock();
- cpuset_for_each_descendant_pre(cp, pos_css, cs) {
- struct cpuset *parent = parent_cs(cp);
-
- nodes_and(*new_mems, cp->mems_allowed, parent->effective_mems);
-
- /*
- * If it becomes empty, inherit the effective mask of the
- * parent, which is guaranteed to have some MEMs.
- */
- if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
- nodes_empty(*new_mems))
- *new_mems = parent->effective_mems;
-
- /* Skip the whole subtree if the nodemask remains the same. */
- if (nodes_equal(*new_mems, cp->effective_mems)) {
- pos_css = css_rightmost_descendant(pos_css);
- continue;
- }
-
- if (!css_tryget_online(&cp->css))
- continue;
- rcu_read_unlock();
-
- spin_lock_irq(&callback_lock);
- cp->effective_mems = *new_mems;
- spin_unlock_irq(&callback_lock);
-
- WARN_ON(!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
- !nodes_equal(cp->mems_allowed, cp->effective_mems));
-
- update_tasks_nodemask(cp);
-
- rcu_read_lock();
- css_put(&cp->css);
- }
- rcu_read_unlock();
-}
-
-/*
- * Handle user request to change the 'mems' memory placement
- * of a cpuset. Needs to validate the request, update the
- * cpusets mems_allowed, and for each task in the cpuset,
- * update mems_allowed and rebind task's mempolicy and any vma
- * mempolicies and if the cpuset is marked 'memory_migrate',
- * migrate the tasks pages to the new memory.
- *
- * Call with cpuset_mutex held. May take callback_lock during call.
- * Will take tasklist_lock, scan tasklist for tasks in cpuset cs,
- * lock each such tasks mm->mmap_sem, scan its vma's and rebind
- * their mempolicies to the cpusets new mems_allowed.
- */
-static int update_nodemask(struct cpuset *cs, struct cpuset *trialcs,
- const char *buf)
-{
- int retval;
-
- /*
- * top_cpuset.mems_allowed tracks node_stats[N_MEMORY];
- * it's read-only
- */
- if (cs == &top_cpuset) {
- retval = -EACCES;
- goto done;
- }
-
- /*
- * An empty mems_allowed is ok iff there are no tasks in the cpuset.
- * Since nodelist_parse() fails on an empty mask, we special case
- * that parsing. The validate_change() call ensures that cpusets
- * with tasks have memory.
- */
- if (!*buf) {
- nodes_clear(trialcs->mems_allowed);
- } else {
- retval = nodelist_parse(buf, trialcs->mems_allowed);
- if (retval < 0)
- goto done;
-
- if (!nodes_subset(trialcs->mems_allowed,
- top_cpuset.mems_allowed)) {
- retval = -EINVAL;
- goto done;
- }
- }
-
- if (nodes_equal(cs->mems_allowed, trialcs->mems_allowed)) {
- retval = 0; /* Too easy - nothing to do */
- goto done;
- }
- retval = validate_change(cs, trialcs);
- if (retval < 0)
- goto done;
-
- spin_lock_irq(&callback_lock);
- cs->mems_allowed = trialcs->mems_allowed;
- spin_unlock_irq(&callback_lock);
-
- /* use trialcs->mems_allowed as a temp variable */
- update_nodemasks_hier(cs, &trialcs->mems_allowed);
-done:
- return retval;
-}
-
-int current_cpuset_is_being_rebound(void)
-{
- int ret;
-
- rcu_read_lock();
- ret = task_cs(current) == cpuset_being_rebound;
- rcu_read_unlock();
-
- return ret;
-}
-
-static int update_relax_domain_level(struct cpuset *cs, s64 val)
-{
-#ifdef CONFIG_SMP
- if (val < -1 || val >= sched_domain_level_max)
- return -EINVAL;
-#endif
-
- if (val != cs->relax_domain_level) {
- cs->relax_domain_level = val;
- if (!cpumask_empty(cs->cpus_allowed) &&
- is_sched_load_balance(cs))
- rebuild_sched_domains_locked();
- }
-
- return 0;
-}
-
-/**
- * update_tasks_flags - update the spread flags of tasks in the cpuset.
- * @cs: the cpuset in which each task's spread flags needs to be changed
- *
- * Iterate through each task of @cs updating its spread flags. As this
- * function is called with cpuset_mutex held, cpuset membership stays
- * stable.
- */
-static void update_tasks_flags(struct cpuset *cs)
-{
- struct css_task_iter it;
- struct task_struct *task;
-
- css_task_iter_start(&cs->css, &it);
- while ((task = css_task_iter_next(&it)))
- cpuset_update_task_spread_flag(cs, task);
- css_task_iter_end(&it);
-}
-
-/*
- * update_flag - read a 0 or a 1 in a file and update associated flag
- * bit: the bit to update (see cpuset_flagbits_t)
- * cs: the cpuset to update
- * turning_on: whether the flag is being set or cleared
- *
- * Call with cpuset_mutex held.
- */
-
-static int update_flag(cpuset_flagbits_t bit, struct cpuset *cs,
- int turning_on)
-{
- struct cpuset *trialcs;
- int balance_flag_changed;
- int spread_flag_changed;
- int err;
-
- trialcs = alloc_trial_cpuset(cs);
- if (!trialcs)
- return -ENOMEM;
-
- if (turning_on)
- set_bit(bit, &trialcs->flags);
- else
- clear_bit(bit, &trialcs->flags);
-
- err = validate_change(cs, trialcs);
- if (err < 0)
- goto out;
-
- balance_flag_changed = (is_sched_load_balance(cs) !=
- is_sched_load_balance(trialcs));
-
- spread_flag_changed = ((is_spread_slab(cs) != is_spread_slab(trialcs))
- || (is_spread_page(cs) != is_spread_page(trialcs)));
-
- spin_lock_irq(&callback_lock);
- cs->flags = trialcs->flags;
- spin_unlock_irq(&callback_lock);
-
- if (!cpumask_empty(trialcs->cpus_allowed) && balance_flag_changed)
- rebuild_sched_domains_locked();
-
- if (spread_flag_changed)
- update_tasks_flags(cs);
-out:
- free_trial_cpuset(trialcs);
- return err;
-}
-
-/*
- * Frequency meter - How fast is some event occurring?
- *
- * These routines manage a digitally filtered, constant time based,
- * event frequency meter. There are four routines:
- * fmeter_init() - initialize a frequency meter.
- * fmeter_markevent() - called each time the event happens.
- * fmeter_getrate() - returns the recent rate of such events.
- * fmeter_update() - internal routine used to update fmeter.
- *
- * A common data structure is passed to each of these routines,
- * which is used to keep track of the state required to manage the
- * frequency meter and its digital filter.
- *
- * The filter works on the number of events marked per unit time.
- * The filter is single-pole low-pass recursive (IIR). The time unit
- * is 1 second. Arithmetic is done using 32-bit integers scaled to
- * simulate 3 decimal digits of precision (multiplied by 1000).
- *
- * With an FM_COEF of 933, and a time base of 1 second, the filter
- * has a half-life of 10 seconds, meaning that if the events quit
- * happening, then the rate returned from the fmeter_getrate()
- * will be cut in half each 10 seconds, until it converges to zero.
- *
- * It is not worth doing a real infinitely recursive filter. If more
- * than FM_MAXTICKS ticks have elapsed since the last filter event,
- * just compute FM_MAXTICKS ticks worth, by which point the level
- * will be stable.
- *
- * Limit the count of unprocessed events to FM_MAXCNT, so as to avoid
- * arithmetic overflow in the fmeter_update() routine.
- *
- * Given the simple 32 bit integer arithmetic used, this meter works
- * best for reporting rates between one per millisecond (msec) and
- * one per 32 (approx) seconds. At constant rates faster than one
- * per msec it maxes out at values just under 1,000,000. At constant
- * rates between one per msec, and one per second it will stabilize
- * to a value N*1000, where N is the rate of events per second.
- * At constant rates between one per second and one per 32 seconds,
- * it will be choppy, moving up on the seconds that have an event,
- * and then decaying until the next event. At rates slower than
- * about one in 32 seconds, it decays all the way back to zero between
- * each event.
- */
-
-#define FM_COEF 933 /* coefficient for half-life of 10 secs */
-#define FM_MAXTICKS ((u32)99) /* useless computing more ticks than this */
-#define FM_MAXCNT 1000000 /* limit cnt to avoid overflow */
-#define FM_SCALE 1000 /* faux fixed point scale */
-
-/* Initialize a frequency meter */
-static void fmeter_init(struct fmeter *fmp)
-{
- fmp->cnt = 0;
- fmp->val = 0;
- fmp->time = 0;
- spin_lock_init(&fmp->lock);
-}
-
-/* Internal meter update - process cnt events and update value */
-static void fmeter_update(struct fmeter *fmp)
-{
- time64_t now;
- u32 ticks;
-
- now = ktime_get_seconds();
- ticks = now - fmp->time;
-
- if (ticks == 0)
- return;
-
- ticks = min(FM_MAXTICKS, ticks);
- while (ticks-- > 0)
- fmp->val = (FM_COEF * fmp->val) / FM_SCALE;
- fmp->time = now;
-
- fmp->val += ((FM_SCALE - FM_COEF) * fmp->cnt) / FM_SCALE;
- fmp->cnt = 0;
-}
-
-/* Process any previous ticks, then bump cnt by one (times scale). */
-static void fmeter_markevent(struct fmeter *fmp)
-{
- spin_lock(&fmp->lock);
- fmeter_update(fmp);
- fmp->cnt = min(FM_MAXCNT, fmp->cnt + FM_SCALE);
- spin_unlock(&fmp->lock);
-}
-
-/* Process any previous ticks, then return current value. */
-static int fmeter_getrate(struct fmeter *fmp)
-{
- int val;
-
- spin_lock(&fmp->lock);
- fmeter_update(fmp);
- val = fmp->val;
- spin_unlock(&fmp->lock);
- return val;
-}
-
-static struct cpuset *cpuset_attach_old_cs;
-
-/* Called by cgroups to determine if a cpuset is usable; cpuset_mutex held */
-static int cpuset_can_attach(struct cgroup_taskset *tset)
-{
- struct cgroup_subsys_state *css;
- struct cpuset *cs;
- struct task_struct *task;
- int ret;
-
- /* used later by cpuset_attach() */
- cpuset_attach_old_cs = task_cs(cgroup_taskset_first(tset, &css));
- cs = css_cs(css);
-
- mutex_lock(&cpuset_mutex);
-
- /* allow moving tasks into an empty cpuset if on default hierarchy */
- ret = -ENOSPC;
- if (!cgroup_subsys_on_dfl(cpuset_cgrp_subsys) &&
- (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)))
- goto out_unlock;
-
- cgroup_taskset_for_each(task, css, tset) {
- ret = task_can_attach(task, cs->cpus_allowed);
- if (ret)
- goto out_unlock;
- ret = security_task_setscheduler(task);
- if (ret)
- goto out_unlock;
- }
-
- /*
- * Mark attach is in progress. This makes validate_change() fail
- * changes which zero cpus/mems_allowed.
- */
- cs->attach_in_progress++;
- ret = 0;
-out_unlock:
- mutex_unlock(&cpuset_mutex);
- return ret;
-}
-
-static void cpuset_cancel_attach(struct cgroup_taskset *tset)
-{
- struct cgroup_subsys_state *css;
- struct cpuset *cs;
-
- cgroup_taskset_first(tset, &css);
- cs = css_cs(css);
-
- mutex_lock(&cpuset_mutex);
- css_cs(css)->attach_in_progress--;
- mutex_unlock(&cpuset_mutex);
-}
-
-/*
- * Protected by cpuset_mutex. cpus_attach is used only by cpuset_attach()
- * but we can't allocate it dynamically there. Define it global and
- * allocate from cpuset_init().
- */
-static cpumask_var_t cpus_attach;
-
-static void cpuset_attach(struct cgroup_taskset *tset)
-{
- /* static buf protected by cpuset_mutex */
- static nodemask_t cpuset_attach_nodemask_to;
- struct task_struct *task;
- struct task_struct *leader;
- struct cgroup_subsys_state *css;
- struct cpuset *cs;
- struct cpuset *oldcs = cpuset_attach_old_cs;
-
- cgroup_taskset_first(tset, &css);
- cs = css_cs(css);
-
- mutex_lock(&cpuset_mutex);
-
- /* prepare for attach */
- if (cs == &top_cpuset)
- cpumask_copy(cpus_attach, cpu_possible_mask);
- else
- guarantee_online_cpus(cs, cpus_attach);
-
- guarantee_online_mems(cs, &cpuset_attach_nodemask_to);
-
- cgroup_taskset_for_each(task, css, tset) {
- /*
- * can_attach beforehand should guarantee that this doesn't
- * fail. TODO: have a better way to handle failure here
- */
- WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpus_attach));
-
- cpuset_change_task_nodemask(task, &cpuset_attach_nodemask_to);
- cpuset_update_task_spread_flag(cs, task);
- }
-
- /*
- * Change mm for all threadgroup leaders. This is expensive and may
- * sleep and should be moved outside migration path proper.
- */
- cpuset_attach_nodemask_to = cs->effective_mems;
- cgroup_taskset_for_each_leader(leader, css, tset) {
- struct mm_struct *mm = get_task_mm(leader);
-
- if (mm) {
- mpol_rebind_mm(mm, &cpuset_attach_nodemask_to);
-
- /*
- * old_mems_allowed is the same with mems_allowed
- * here, except if this task is being moved
- * automatically due to hotplug. In that case
- * @mems_allowed has been updated and is empty, so
- * @old_mems_allowed is the right nodesets that we
- * migrate mm from.
- */
- if (is_memory_migrate(cs))
- cpuset_migrate_mm(mm, &oldcs->old_mems_allowed,
- &cpuset_attach_nodemask_to);
- else
- mmput(mm);
- }
- }
-
- cs->old_mems_allowed = cpuset_attach_nodemask_to;
-
- cs->attach_in_progress--;
- if (!cs->attach_in_progress)
- wake_up(&cpuset_attach_wq);
-
- mutex_unlock(&cpuset_mutex);
-}
-
-/* The various types of files and directories in a cpuset file system */
-
-typedef enum {
- FILE_MEMORY_MIGRATE,
- FILE_CPULIST,
- FILE_MEMLIST,
- FILE_EFFECTIVE_CPULIST,
- FILE_EFFECTIVE_MEMLIST,
- FILE_CPU_EXCLUSIVE,
- FILE_MEM_EXCLUSIVE,
- FILE_MEM_HARDWALL,
- FILE_SCHED_LOAD_BALANCE,
- FILE_SCHED_RELAX_DOMAIN_LEVEL,
- FILE_MEMORY_PRESSURE_ENABLED,
- FILE_MEMORY_PRESSURE,
- FILE_SPREAD_PAGE,
- FILE_SPREAD_SLAB,
-} cpuset_filetype_t;
-
-static int cpuset_write_u64(struct cgroup_subsys_state *css, struct cftype *cft,
- u64 val)
-{
- struct cpuset *cs = css_cs(css);
- cpuset_filetype_t type = cft->private;
- int retval = 0;
-
- mutex_lock(&cpuset_mutex);
- if (!is_cpuset_online(cs)) {
- retval = -ENODEV;
- goto out_unlock;
- }
-
- switch (type) {
- case FILE_CPU_EXCLUSIVE:
- retval = update_flag(CS_CPU_EXCLUSIVE, cs, val);
- break;
- case FILE_MEM_EXCLUSIVE:
- retval = update_flag(CS_MEM_EXCLUSIVE, cs, val);
- break;
- case FILE_MEM_HARDWALL:
- retval = update_flag(CS_MEM_HARDWALL, cs, val);
- break;
- case FILE_SCHED_LOAD_BALANCE:
- retval = update_flag(CS_SCHED_LOAD_BALANCE, cs, val);
- break;
- case FILE_MEMORY_MIGRATE:
- retval = update_flag(CS_MEMORY_MIGRATE, cs, val);
- break;
- case FILE_MEMORY_PRESSURE_ENABLED:
- cpuset_memory_pressure_enabled = !!val;
- break;
- case FILE_SPREAD_PAGE:
- retval = update_flag(CS_SPREAD_PAGE, cs, val);
- break;
- case FILE_SPREAD_SLAB:
- retval = update_flag(CS_SPREAD_SLAB, cs, val);
- break;
- default:
- retval = -EINVAL;
- break;
- }
-out_unlock:
- mutex_unlock(&cpuset_mutex);
- return retval;
-}
-
-static int cpuset_write_s64(struct cgroup_subsys_state *css, struct cftype *cft,
- s64 val)
-{
- struct cpuset *cs = css_cs(css);
- cpuset_filetype_t type = cft->private;
- int retval = -ENODEV;
-
- mutex_lock(&cpuset_mutex);
- if (!is_cpuset_online(cs))
- goto out_unlock;
-
- switch (type) {
- case FILE_SCHED_RELAX_DOMAIN_LEVEL:
- retval = update_relax_domain_level(cs, val);
- break;
- default:
- retval = -EINVAL;
- break;
- }
-out_unlock:
- mutex_unlock(&cpuset_mutex);
- return retval;
-}
-
-/*
- * Common handling for a write to a "cpus" or "mems" file.
- */
-static ssize_t cpuset_write_resmask(struct kernfs_open_file *of,
- char *buf, size_t nbytes, loff_t off)
-{
- struct cpuset *cs = css_cs(of_css(of));
- struct cpuset *trialcs;
- int retval = -ENODEV;
-
- buf = strstrip(buf);
-
- /*
- * CPU or memory hotunplug may leave @cs w/o any execution
- * resources, in which case the hotplug code asynchronously updates
- * configuration and transfers all tasks to the nearest ancestor
- * which can execute.
- *
- * As writes to "cpus" or "mems" may restore @cs's execution
- * resources, wait for the previously scheduled operations before
- * proceeding, so that we don't end up keep removing tasks added
- * after execution capability is restored.
- *
- * cpuset_hotplug_work calls back into cgroup core via
- * cgroup_transfer_tasks() and waiting for it from a cgroupfs
- * operation like this one can lead to a deadlock through kernfs
- * active_ref protection. Let's break the protection. Losing the
- * protection is okay as we check whether @cs is online after
- * grabbing cpuset_mutex anyway. This only happens on the legacy
- * hierarchies.
- */
- css_get(&cs->css);
- kernfs_break_active_protection(of->kn);
- flush_work(&cpuset_hotplug_work);
-
- mutex_lock(&cpuset_mutex);
- if (!is_cpuset_online(cs))
- goto out_unlock;
-
- trialcs = alloc_trial_cpuset(cs);
- if (!trialcs) {
- retval = -ENOMEM;
- goto out_unlock;
- }
-
- switch (of_cft(of)->private) {
- case FILE_CPULIST:
- retval = update_cpumask(cs, trialcs, buf);
- break;
- case FILE_MEMLIST:
- retval = update_nodemask(cs, trialcs, buf);
- break;
- default:
- retval = -EINVAL;
- break;
- }
-
- free_trial_cpuset(trialcs);
-out_unlock:
- mutex_unlock(&cpuset_mutex);
- kernfs_unbreak_active_protection(of->kn);
- css_put(&cs->css);
- flush_workqueue(cpuset_migrate_mm_wq);
- return retval ?: nbytes;
-}
-
-/*
- * These ascii lists should be read in a single call, by using a user
- * buffer large enough to hold the entire map. If read in smaller
- * chunks, there is no guarantee of atomicity. Since the display format
- * used, list of ranges of sequential numbers, is variable length,
- * and since these maps can change value dynamically, one could read
- * gibberish by doing partial reads while a list was changing.
- */
-static int cpuset_common_seq_show(struct seq_file *sf, void *v)
-{
- struct cpuset *cs = css_cs(seq_css(sf));
- cpuset_filetype_t type = seq_cft(sf)->private;
- int ret = 0;
-
- spin_lock_irq(&callback_lock);
-
- switch (type) {
- case FILE_CPULIST:
- seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->cpus_allowed));
- break;
- case FILE_MEMLIST:
- seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->mems_allowed));
- break;
- case FILE_EFFECTIVE_CPULIST:
- seq_printf(sf, "%*pbl\n", cpumask_pr_args(cs->effective_cpus));
- break;
- case FILE_EFFECTIVE_MEMLIST:
- seq_printf(sf, "%*pbl\n", nodemask_pr_args(&cs->effective_mems));
- break;
- default:
- ret = -EINVAL;
- }
-
- spin_unlock_irq(&callback_lock);
- return ret;
-}
-
-static u64 cpuset_read_u64(struct cgroup_subsys_state *css, struct cftype *cft)
-{
- struct cpuset *cs = css_cs(css);
- cpuset_filetype_t type = cft->private;
- switch (type) {
- case FILE_CPU_EXCLUSIVE:
- return is_cpu_exclusive(cs);
- case FILE_MEM_EXCLUSIVE:
- return is_mem_exclusive(cs);
- case FILE_MEM_HARDWALL:
- return is_mem_hardwall(cs);
- case FILE_SCHED_LOAD_BALANCE:
- return is_sched_load_balance(cs);
- case FILE_MEMORY_MIGRATE:
- return is_memory_migrate(cs);
- case FILE_MEMORY_PRESSURE_ENABLED:
- return cpuset_memory_pressure_enabled;
- case FILE_MEMORY_PRESSURE:
- return fmeter_getrate(&cs->fmeter);
- case FILE_SPREAD_PAGE:
- return is_spread_page(cs);
- case FILE_SPREAD_SLAB:
- return is_spread_slab(cs);
- default:
- BUG();
- }
-
- /* Unreachable but makes gcc happy */
- return 0;
-}
-
-static s64 cpuset_read_s64(struct cgroup_subsys_state *css, struct cftype *cft)
-{
- struct cpuset *cs = css_cs(css);
- cpuset_filetype_t type = cft->private;
- switch (type) {
- case FILE_SCHED_RELAX_DOMAIN_LEVEL:
- return cs->relax_domain_level;
- default:
- BUG();
- }
-
- /* Unrechable but makes gcc happy */
- return 0;
-}
-
-
-/*
- * for the common functions, 'private' gives the type of file
- */
-
-static struct cftype files[] = {
- {
- .name = "cpus",
- .seq_show = cpuset_common_seq_show,
- .write = cpuset_write_resmask,
- .max_write_len = (100U + 6 * NR_CPUS),
- .private = FILE_CPULIST,
- },
-
- {
- .name = "mems",
- .seq_show = cpuset_common_seq_show,
- .write = cpuset_write_resmask,
- .max_write_len = (100U + 6 * MAX_NUMNODES),
- .private = FILE_MEMLIST,
- },
-
- {
- .name = "effective_cpus",
- .seq_show = cpuset_common_seq_show,
- .private = FILE_EFFECTIVE_CPULIST,
- },
-
- {
- .name = "effective_mems",
- .seq_show = cpuset_common_seq_show,
- .private = FILE_EFFECTIVE_MEMLIST,
- },
-
- {
- .name = "cpu_exclusive",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_CPU_EXCLUSIVE,
- },
-
- {
- .name = "mem_exclusive",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_MEM_EXCLUSIVE,
- },
-
- {
- .name = "mem_hardwall",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_MEM_HARDWALL,
- },
-
- {
- .name = "sched_load_balance",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_SCHED_LOAD_BALANCE,
- },
-
- {
- .name = "sched_relax_domain_level",
- .read_s64 = cpuset_read_s64,
- .write_s64 = cpuset_write_s64,
- .private = FILE_SCHED_RELAX_DOMAIN_LEVEL,
- },
-
- {
- .name = "memory_migrate",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_MEMORY_MIGRATE,
- },
-
- {
- .name = "memory_pressure",
- .read_u64 = cpuset_read_u64,
- },
-
- {
- .name = "memory_spread_page",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_SPREAD_PAGE,
- },
-
- {
- .name = "memory_spread_slab",
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_SPREAD_SLAB,
- },
-
- {
- .name = "memory_pressure_enabled",
- .flags = CFTYPE_ONLY_ON_ROOT,
- .read_u64 = cpuset_read_u64,
- .write_u64 = cpuset_write_u64,
- .private = FILE_MEMORY_PRESSURE_ENABLED,
- },
-
- { } /* terminate */
-};
-
-/*
- * cpuset_css_alloc - allocate a cpuset css
- * cgrp: control group that the new cpuset will be part of
- */
-
-static struct cgroup_subsys_state *
-cpuset_css_alloc(struct cgroup_subsys_state *parent_css)
-{
- struct cpuset *cs;
-
- if (!parent_css)
- return &top_cpuset.css;
-
- cs = kzalloc(sizeof(*cs), GFP_KERNEL);
- if (!cs)
- return ERR_PTR(-ENOMEM);
- if (!alloc_cpumask_var(&cs->cpus_allowed, GFP_KERNEL))
- goto free_cs;
- if (!alloc_cpumask_var(&cs->effective_cpus, GFP_KERNEL))
- goto free_cpus;
-
- set_bit(CS_SCHED_LOAD_BALANCE, &cs->flags);
- cpumask_clear(cs->cpus_allowed);
- nodes_clear(cs->mems_allowed);
- cpumask_clear(cs->effective_cpus);
- nodes_clear(cs->effective_mems);
- fmeter_init(&cs->fmeter);
- cs->relax_domain_level = -1;
-
- return &cs->css;
-
-free_cpus:
- free_cpumask_var(cs->cpus_allowed);
-free_cs:
- kfree(cs);
- return ERR_PTR(-ENOMEM);
-}
-
-static int cpuset_css_online(struct cgroup_subsys_state *css)
-{
- struct cpuset *cs = css_cs(css);
- struct cpuset *parent = parent_cs(cs);
- struct cpuset *tmp_cs;
- struct cgroup_subsys_state *pos_css;
-
- if (!parent)
- return 0;
-
- mutex_lock(&cpuset_mutex);
-
- set_bit(CS_ONLINE, &cs->flags);
- if (is_spread_page(parent))
- set_bit(CS_SPREAD_PAGE, &cs->flags);
- if (is_spread_slab(parent))
- set_bit(CS_SPREAD_SLAB, &cs->flags);
-
- cpuset_inc();
-
- spin_lock_irq(&callback_lock);
- if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
- cpumask_copy(cs->effective_cpus, parent->effective_cpus);
- cs->effective_mems = parent->effective_mems;
- }
- spin_unlock_irq(&callback_lock);
-
- if (!test_bit(CGRP_CPUSET_CLONE_CHILDREN, &css->cgroup->flags))
- goto out_unlock;
-
- /*
- * Clone @parent's configuration if CGRP_CPUSET_CLONE_CHILDREN is
- * set. This flag handling is implemented in cgroup core for
- * histrical reasons - the flag may be specified during mount.
- *
- * Currently, if any sibling cpusets have exclusive cpus or mem, we
- * refuse to clone the configuration - thereby refusing the task to
- * be entered, and as a result refusing the sys_unshare() or
- * clone() which initiated it. If this becomes a problem for some
- * users who wish to allow that scenario, then this could be
- * changed to grant parent->cpus_allowed-sibling_cpus_exclusive
- * (and likewise for mems) to the new cgroup.
- */
- rcu_read_lock();
- cpuset_for_each_child(tmp_cs, pos_css, parent) {
- if (is_mem_exclusive(tmp_cs) || is_cpu_exclusive(tmp_cs)) {
- rcu_read_unlock();
- goto out_unlock;
- }
- }
- rcu_read_unlock();
-
- spin_lock_irq(&callback_lock);
- cs->mems_allowed = parent->mems_allowed;
- cs->effective_mems = parent->mems_allowed;
- cpumask_copy(cs->cpus_allowed, parent->cpus_allowed);
- cpumask_copy(cs->effective_cpus, parent->cpus_allowed);
- spin_unlock_irq(&callback_lock);
-out_unlock:
- mutex_unlock(&cpuset_mutex);
- return 0;
-}
-
-/*
- * If the cpuset being removed has its flag 'sched_load_balance'
- * enabled, then simulate turning sched_load_balance off, which
- * will call rebuild_sched_domains_locked().
- */
-
-static void cpuset_css_offline(struct cgroup_subsys_state *css)
-{
- struct cpuset *cs = css_cs(css);
-
- mutex_lock(&cpuset_mutex);
-
- if (is_sched_load_balance(cs))
- update_flag(CS_SCHED_LOAD_BALANCE, cs, 0);
-
- cpuset_dec();
- clear_bit(CS_ONLINE, &cs->flags);
-
- mutex_unlock(&cpuset_mutex);
-}
-
-static void cpuset_css_free(struct cgroup_subsys_state *css)
-{
- struct cpuset *cs = css_cs(css);
-
- free_cpumask_var(cs->effective_cpus);
- free_cpumask_var(cs->cpus_allowed);
- kfree(cs);
-}
-
-static void cpuset_bind(struct cgroup_subsys_state *root_css)
-{
- mutex_lock(&cpuset_mutex);
- spin_lock_irq(&callback_lock);
-
- if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys)) {
- cpumask_copy(top_cpuset.cpus_allowed, cpu_possible_mask);
- top_cpuset.mems_allowed = node_possible_map;
- } else {
- cpumask_copy(top_cpuset.cpus_allowed,
- top_cpuset.effective_cpus);
- top_cpuset.mems_allowed = top_cpuset.effective_mems;
- }
-
- spin_unlock_irq(&callback_lock);
- mutex_unlock(&cpuset_mutex);
-}
-
-/*
- * Make sure the new task conform to the current state of its parent,
- * which could have been changed by cpuset just after it inherits the
- * state from the parent and before it sits on the cgroup's task list.
- */
-static void cpuset_fork(struct task_struct *task)
-{
- if (task_css_is_root(task, cpuset_cgrp_id))
- return;
-
- set_cpus_allowed_ptr(task, ¤t->cpus_allowed);
- task->mems_allowed = current->mems_allowed;
-}
-
-struct cgroup_subsys cpuset_cgrp_subsys = {
- .css_alloc = cpuset_css_alloc,
- .css_online = cpuset_css_online,
- .css_offline = cpuset_css_offline,
- .css_free = cpuset_css_free,
- .can_attach = cpuset_can_attach,
- .cancel_attach = cpuset_cancel_attach,
- .attach = cpuset_attach,
- .post_attach = cpuset_post_attach,
- .bind = cpuset_bind,
- .fork = cpuset_fork,
- .legacy_cftypes = files,
- .early_init = true,
-};
-
-/**
- * cpuset_init - initialize cpusets at system boot
- *
- * Description: Initialize top_cpuset and the cpuset internal file system,
- **/
-
-int __init cpuset_init(void)
-{
- int err = 0;
-
- if (!alloc_cpumask_var(&top_cpuset.cpus_allowed, GFP_KERNEL))
- BUG();
- if (!alloc_cpumask_var(&top_cpuset.effective_cpus, GFP_KERNEL))
- BUG();
-
- cpumask_setall(top_cpuset.cpus_allowed);
- nodes_setall(top_cpuset.mems_allowed);
- cpumask_setall(top_cpuset.effective_cpus);
- nodes_setall(top_cpuset.effective_mems);
-
- fmeter_init(&top_cpuset.fmeter);
- set_bit(CS_SCHED_LOAD_BALANCE, &top_cpuset.flags);
- top_cpuset.relax_domain_level = -1;
-
- err = register_filesystem(&cpuset_fs_type);
- if (err < 0)
- return err;
-
- if (!alloc_cpumask_var(&cpus_attach, GFP_KERNEL))
- BUG();
-
- return 0;
-}
-
-/*
- * If CPU and/or memory hotplug handlers, below, unplug any CPUs
- * or memory nodes, we need to walk over the cpuset hierarchy,
- * removing that CPU or node from all cpusets. If this removes the
- * last CPU or node from a cpuset, then move the tasks in the empty
- * cpuset to its next-highest non-empty parent.
- */
-static void remove_tasks_in_empty_cpuset(struct cpuset *cs)
-{
- struct cpuset *parent;
-
- /*
- * Find its next-highest non-empty parent, (top cpuset
- * has online cpus, so can't be empty).
- */
- parent = parent_cs(cs);
- while (cpumask_empty(parent->cpus_allowed) ||
- nodes_empty(parent->mems_allowed))
- parent = parent_cs(parent);
-
- if (cgroup_transfer_tasks(parent->css.cgroup, cs->css.cgroup)) {
- pr_err("cpuset: failed to transfer tasks out of empty cpuset ");
- pr_cont_cgroup_name(cs->css.cgroup);
- pr_cont("\n");
- }
-}
-
-static void
-hotplug_update_tasks_legacy(struct cpuset *cs,
- struct cpumask *new_cpus, nodemask_t *new_mems,
- bool cpus_updated, bool mems_updated)
-{
- bool is_empty;
-
- spin_lock_irq(&callback_lock);
- cpumask_copy(cs->cpus_allowed, new_cpus);
- cpumask_copy(cs->effective_cpus, new_cpus);
- cs->mems_allowed = *new_mems;
- cs->effective_mems = *new_mems;
- spin_unlock_irq(&callback_lock);
-
- /*
- * Don't call update_tasks_cpumask() if the cpuset becomes empty,
- * as the tasks will be migratecd to an ancestor.
- */
- if (cpus_updated && !cpumask_empty(cs->cpus_allowed))
- update_tasks_cpumask(cs);
- if (mems_updated && !nodes_empty(cs->mems_allowed))
- update_tasks_nodemask(cs);
-
- is_empty = cpumask_empty(cs->cpus_allowed) ||
- nodes_empty(cs->mems_allowed);
-
- mutex_unlock(&cpuset_mutex);
-
- /*
- * Move tasks to the nearest ancestor with execution resources,
- * This is full cgroup operation which will also call back into
- * cpuset. Should be done outside any lock.
- */
- if (is_empty)
- remove_tasks_in_empty_cpuset(cs);
-
- mutex_lock(&cpuset_mutex);
-}
-
-static void
-hotplug_update_tasks(struct cpuset *cs,
- struct cpumask *new_cpus, nodemask_t *new_mems,
- bool cpus_updated, bool mems_updated)
-{
- if (cpumask_empty(new_cpus))
- cpumask_copy(new_cpus, parent_cs(cs)->effective_cpus);
- if (nodes_empty(*new_mems))
- *new_mems = parent_cs(cs)->effective_mems;
-
- spin_lock_irq(&callback_lock);
- cpumask_copy(cs->effective_cpus, new_cpus);
- cs->effective_mems = *new_mems;
- spin_unlock_irq(&callback_lock);
-
- if (cpus_updated)
- update_tasks_cpumask(cs);
- if (mems_updated)
- update_tasks_nodemask(cs);
-}
-
-/**
- * cpuset_hotplug_update_tasks - update tasks in a cpuset for hotunplug
- * @cs: cpuset in interest
- *
- * Compare @cs's cpu and mem masks against top_cpuset and if some have gone
- * offline, update @cs accordingly. If @cs ends up with no CPU or memory,
- * all its tasks are moved to the nearest ancestor with both resources.
- */
-static void cpuset_hotplug_update_tasks(struct cpuset *cs)
-{
- static cpumask_t new_cpus;
- static nodemask_t new_mems;
- bool cpus_updated;
- bool mems_updated;
-retry:
- wait_event(cpuset_attach_wq, cs->attach_in_progress == 0);
-
- mutex_lock(&cpuset_mutex);
-
- /*
- * We have raced with task attaching. We wait until attaching
- * is finished, so we won't attach a task to an empty cpuset.
- */
- if (cs->attach_in_progress) {
- mutex_unlock(&cpuset_mutex);
- goto retry;
- }
-
- cpumask_and(&new_cpus, cs->cpus_allowed, parent_cs(cs)->effective_cpus);
- nodes_and(new_mems, cs->mems_allowed, parent_cs(cs)->effective_mems);
-
- cpus_updated = !cpumask_equal(&new_cpus, cs->effective_cpus);
- mems_updated = !nodes_equal(new_mems, cs->effective_mems);
-
- if (cgroup_subsys_on_dfl(cpuset_cgrp_subsys))
- hotplug_update_tasks(cs, &new_cpus, &new_mems,
- cpus_updated, mems_updated);
- else
- hotplug_update_tasks_legacy(cs, &new_cpus, &new_mems,
- cpus_updated, mems_updated);
-
- mutex_unlock(&cpuset_mutex);
-}
-
-/**
- * cpuset_hotplug_workfn - handle CPU/memory hotunplug for a cpuset
- *
- * This function is called after either CPU or memory configuration has
- * changed and updates cpuset accordingly. The top_cpuset is always
- * synchronized to cpu_active_mask and N_MEMORY, which is necessary in
- * order to make cpusets transparent (of no affect) on systems that are
- * actively using CPU hotplug but making no active use of cpusets.
- *
- * Non-root cpusets are only affected by offlining. If any CPUs or memory
- * nodes have been taken down, cpuset_hotplug_update_tasks() is invoked on
- * all descendants.
- *
- * Note that CPU offlining during suspend is ignored. We don't modify
- * cpusets across suspend/resume cycles at all.
- */
-static void cpuset_hotplug_workfn(struct work_struct *work)
-{
- static cpumask_t new_cpus;
- static nodemask_t new_mems;
- bool cpus_updated, mems_updated;
- bool on_dfl = cgroup_subsys_on_dfl(cpuset_cgrp_subsys);
-
- mutex_lock(&cpuset_mutex);
-
- /* fetch the available cpus/mems and find out which changed how */
- cpumask_copy(&new_cpus, cpu_active_mask);
- new_mems = node_states[N_MEMORY];
-
- cpus_updated = !cpumask_equal(top_cpuset.effective_cpus, &new_cpus);
- mems_updated = !nodes_equal(top_cpuset.effective_mems, new_mems);
-
- /* synchronize cpus_allowed to cpu_active_mask */
- if (cpus_updated) {
- spin_lock_irq(&callback_lock);
- if (!on_dfl)
- cpumask_copy(top_cpuset.cpus_allowed, &new_cpus);
- cpumask_copy(top_cpuset.effective_cpus, &new_cpus);
- spin_unlock_irq(&callback_lock);
- /* we don't mess with cpumasks of tasks in top_cpuset */
- }
-
- /* synchronize mems_allowed to N_MEMORY */
- if (mems_updated) {
- spin_lock_irq(&callback_lock);
- if (!on_dfl)
- top_cpuset.mems_allowed = new_mems;
- top_cpuset.effective_mems = new_mems;
- spin_unlock_irq(&callback_lock);
- update_tasks_nodemask(&top_cpuset);
- }
-
- mutex_unlock(&cpuset_mutex);
-
- /* if cpus or mems changed, we need to propagate to descendants */
- if (cpus_updated || mems_updated) {
- struct cpuset *cs;
- struct cgroup_subsys_state *pos_css;
-
- rcu_read_lock();
- cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
- if (cs == &top_cpuset || !css_tryget_online(&cs->css))
- continue;
- rcu_read_unlock();
-
- cpuset_hotplug_update_tasks(cs);
-
- rcu_read_lock();
- css_put(&cs->css);
- }
- rcu_read_unlock();
- }
-
- /* rebuild sched domains if cpus_allowed has changed */
- if (cpus_updated)
- rebuild_sched_domains();
-}
-
-void cpuset_update_active_cpus(bool cpu_online)
-{
- /*
- * We're inside cpu hotplug critical region which usually nests
- * inside cgroup synchronization. Bounce actual hotplug processing
- * to a work item to avoid reverse locking order.
- *
- * We still need to do partition_sched_domains() synchronously;
- * otherwise, the scheduler will get confused and put tasks to the
- * dead CPU. Fall back to the default single domain.
- * cpuset_hotplug_workfn() will rebuild it as necessary.
- */
- partition_sched_domains(1, NULL, NULL);
- schedule_work(&cpuset_hotplug_work);
-}
-
-/*
- * Keep top_cpuset.mems_allowed tracking node_states[N_MEMORY].
- * Call this routine anytime after node_states[N_MEMORY] changes.
- * See cpuset_update_active_cpus() for CPU hotplug handling.
- */
-static int cpuset_track_online_nodes(struct notifier_block *self,
- unsigned long action, void *arg)
-{
- schedule_work(&cpuset_hotplug_work);
- return NOTIFY_OK;
-}
-
-static struct notifier_block cpuset_track_online_nodes_nb = {
- .notifier_call = cpuset_track_online_nodes,
- .priority = 10, /* ??! */
-};
-
-/**
- * cpuset_init_smp - initialize cpus_allowed
- *
- * Description: Finish top cpuset after cpu, node maps are initialized
- */
-void __init cpuset_init_smp(void)
-{
- cpumask_copy(top_cpuset.cpus_allowed, cpu_active_mask);
- top_cpuset.mems_allowed = node_states[N_MEMORY];
- top_cpuset.old_mems_allowed = top_cpuset.mems_allowed;
-
- cpumask_copy(top_cpuset.effective_cpus, cpu_active_mask);
- top_cpuset.effective_mems = node_states[N_MEMORY];
-
- register_hotmemory_notifier(&cpuset_track_online_nodes_nb);
-
- cpuset_migrate_mm_wq = alloc_ordered_workqueue("cpuset_migrate_mm", 0);
- BUG_ON(!cpuset_migrate_mm_wq);
-}
-
-/**
- * cpuset_cpus_allowed - return cpus_allowed mask from a tasks cpuset.
- * @tsk: pointer to task_struct from which to obtain cpuset->cpus_allowed.
- * @pmask: pointer to struct cpumask variable to receive cpus_allowed set.
- *
- * Description: Returns the cpumask_var_t cpus_allowed of the cpuset
- * attached to the specified @tsk. Guaranteed to return some non-empty
- * subset of cpu_online_mask, even if this means going outside the
- * tasks cpuset.
- **/
-
-void cpuset_cpus_allowed(struct task_struct *tsk, struct cpumask *pmask)
-{
- unsigned long flags;
-
- spin_lock_irqsave(&callback_lock, flags);
- rcu_read_lock();
- guarantee_online_cpus(task_cs(tsk), pmask);
- rcu_read_unlock();
- spin_unlock_irqrestore(&callback_lock, flags);
-}
-
-void cpuset_cpus_allowed_fallback(struct task_struct *tsk)
-{
- rcu_read_lock();
- do_set_cpus_allowed(tsk, task_cs(tsk)->effective_cpus);
- rcu_read_unlock();
-
- /*
- * We own tsk->cpus_allowed, nobody can change it under us.
- *
- * But we used cs && cs->cpus_allowed lockless and thus can
- * race with cgroup_attach_task() or update_cpumask() and get
- * the wrong tsk->cpus_allowed. However, both cases imply the
- * subsequent cpuset_change_cpumask()->set_cpus_allowed_ptr()
- * which takes task_rq_lock().
- *
- * If we are called after it dropped the lock we must see all
- * changes in tsk_cs()->cpus_allowed. Otherwise we can temporary
- * set any mask even if it is not right from task_cs() pov,
- * the pending set_cpus_allowed_ptr() will fix things.
- *
- * select_fallback_rq() will fix things ups and set cpu_possible_mask
- * if required.
- */
-}
-
-void __init cpuset_init_current_mems_allowed(void)
-{
- nodes_setall(current->mems_allowed);
-}
-
-/**
- * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
- * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
- *
- * Description: Returns the nodemask_t mems_allowed of the cpuset
- * attached to the specified @tsk. Guaranteed to return some non-empty
- * subset of node_states[N_MEMORY], even if this means going outside the
- * tasks cpuset.
- **/
-
-nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
-{
- nodemask_t mask;
- unsigned long flags;
-
- spin_lock_irqsave(&callback_lock, flags);
- rcu_read_lock();
- guarantee_online_mems(task_cs(tsk), &mask);
- rcu_read_unlock();
- spin_unlock_irqrestore(&callback_lock, flags);
-
- return mask;
-}
-
-/**
- * cpuset_nodemask_valid_mems_allowed - check nodemask vs. curremt mems_allowed
- * @nodemask: the nodemask to be checked
- *
- * Are any of the nodes in the nodemask allowed in current->mems_allowed?
- */
-int cpuset_nodemask_valid_mems_allowed(nodemask_t *nodemask)
-{
- return nodes_intersects(*nodemask, current->mems_allowed);
-}
-
-/*
- * nearest_hardwall_ancestor() - Returns the nearest mem_exclusive or
- * mem_hardwall ancestor to the specified cpuset. Call holding
- * callback_lock. If no ancestor is mem_exclusive or mem_hardwall
- * (an unusual configuration), then returns the root cpuset.
- */
-static struct cpuset *nearest_hardwall_ancestor(struct cpuset *cs)
-{
- while (!(is_mem_exclusive(cs) || is_mem_hardwall(cs)) && parent_cs(cs))
- cs = parent_cs(cs);
- return cs;
-}
-
-/**
- * cpuset_node_allowed - Can we allocate on a memory node?
- * @node: is this an allowed node?
- * @gfp_mask: memory allocation flags
- *
- * If we're in interrupt, yes, we can always allocate. If @node is set in
- * current's mems_allowed, yes. If it's not a __GFP_HARDWALL request and this
- * node is set in the nearest hardwalled cpuset ancestor to current's cpuset,
- * yes. If current has access to memory reserves due to TIF_MEMDIE, yes.
- * Otherwise, no.
- *
- * GFP_USER allocations are marked with the __GFP_HARDWALL bit,
- * and do not allow allocations outside the current tasks cpuset
- * unless the task has been OOM killed as is marked TIF_MEMDIE.
- * GFP_KERNEL allocations are not so marked, so can escape to the
- * nearest enclosing hardwalled ancestor cpuset.
- *
- * Scanning up parent cpusets requires callback_lock. The
- * __alloc_pages() routine only calls here with __GFP_HARDWALL bit
- * _not_ set if it's a GFP_KERNEL allocation, and all nodes in the
- * current tasks mems_allowed came up empty on the first pass over
- * the zonelist. So only GFP_KERNEL allocations, if all nodes in the
- * cpuset are short of memory, might require taking the callback_lock.
- *
- * The first call here from mm/page_alloc:get_page_from_freelist()
- * has __GFP_HARDWALL set in gfp_mask, enforcing hardwall cpusets,
- * so no allocation on a node outside the cpuset is allowed (unless
- * in interrupt, of course).
- *
- * The second pass through get_page_from_freelist() doesn't even call
- * here for GFP_ATOMIC calls. For those calls, the __alloc_pages()
- * variable 'wait' is not set, and the bit ALLOC_CPUSET is not set
- * in alloc_flags. That logic and the checks below have the combined
- * affect that:
- * in_interrupt - any node ok (current task context irrelevant)
- * GFP_ATOMIC - any node ok
- * TIF_MEMDIE - any node ok
- * GFP_KERNEL - any node in enclosing hardwalled cpuset ok
- * GFP_USER - only nodes in current tasks mems allowed ok.
- */
-bool __cpuset_node_allowed(int node, gfp_t gfp_mask)
-{
- struct cpuset *cs; /* current cpuset ancestors */
- int allowed; /* is allocation in zone z allowed? */
- unsigned long flags;
-
- if (in_interrupt())
- return true;
- if (node_isset(node, current->mems_allowed))
- return true;
- /*
- * Allow tasks that have access to memory reserves because they have
- * been OOM killed to get memory anywhere.
- */
- if (unlikely(test_thread_flag(TIF_MEMDIE)))
- return true;
- if (gfp_mask & __GFP_HARDWALL) /* If hardwall request, stop here */
- return false;
-
- if (current->flags & PF_EXITING) /* Let dying task have memory */
- return true;
-
- /* Not hardwall and node outside mems_allowed: scan up cpusets */
- spin_lock_irqsave(&callback_lock, flags);
-
- rcu_read_lock();
- cs = nearest_hardwall_ancestor(task_cs(current));
- allowed = node_isset(node, cs->mems_allowed);
- rcu_read_unlock();
-
- spin_unlock_irqrestore(&callback_lock, flags);
- return allowed;
-}
-
-/**
- * cpuset_mem_spread_node() - On which node to begin search for a file page
- * cpuset_slab_spread_node() - On which node to begin search for a slab page
- *
- * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for
- * tasks in a cpuset with is_spread_page or is_spread_slab set),
- * and if the memory allocation used cpuset_mem_spread_node()
- * to determine on which node to start looking, as it will for
- * certain page cache or slab cache pages such as used for file
- * system buffers and inode caches, then instead of starting on the
- * local node to look for a free page, rather spread the starting
- * node around the tasks mems_allowed nodes.
- *
- * We don't have to worry about the returned node being offline
- * because "it can't happen", and even if it did, it would be ok.
- *
- * The routines calling guarantee_online_mems() are careful to
- * only set nodes in task->mems_allowed that are online. So it
- * should not be possible for the following code to return an
- * offline node. But if it did, that would be ok, as this routine
- * is not returning the node where the allocation must be, only
- * the node where the search should start. The zonelist passed to
- * __alloc_pages() will include all nodes. If the slab allocator
- * is passed an offline node, it will fall back to the local node.
- * See kmem_cache_alloc_node().
- */
-
-static int cpuset_spread_node(int *rotor)
-{
- return *rotor = next_node_in(*rotor, current->mems_allowed);
-}
-
-int cpuset_mem_spread_node(void)
-{
- if (current->cpuset_mem_spread_rotor == NUMA_NO_NODE)
- current->cpuset_mem_spread_rotor =
- node_random(¤t->mems_allowed);
-
- return cpuset_spread_node(¤t->cpuset_mem_spread_rotor);
-}
-
-int cpuset_slab_spread_node(void)
-{
- if (current->cpuset_slab_spread_rotor == NUMA_NO_NODE)
- current->cpuset_slab_spread_rotor =
- node_random(¤t->mems_allowed);
-
- return cpuset_spread_node(¤t->cpuset_slab_spread_rotor);
-}
-
-EXPORT_SYMBOL_GPL(cpuset_mem_spread_node);
-
-/**
- * cpuset_mems_allowed_intersects - Does @tsk1's mems_allowed intersect @tsk2's?
- * @tsk1: pointer to task_struct of some task.
- * @tsk2: pointer to task_struct of some other task.
- *
- * Description: Return true if @tsk1's mems_allowed intersects the
- * mems_allowed of @tsk2. Used by the OOM killer to determine if
- * one of the task's memory usage might impact the memory available
- * to the other.
- **/
-
-int cpuset_mems_allowed_intersects(const struct task_struct *tsk1,
- const struct task_struct *tsk2)
-{
- return nodes_intersects(tsk1->mems_allowed, tsk2->mems_allowed);
-}
-
-/**
- * cpuset_print_current_mems_allowed - prints current's cpuset and mems_allowed
- *
- * Description: Prints current's name, cpuset name, and cached copy of its
- * mems_allowed to the kernel log.
- */
-void cpuset_print_current_mems_allowed(void)
-{
- struct cgroup *cgrp;
-
- rcu_read_lock();
-
- cgrp = task_cs(current)->css.cgroup;
- pr_info("%s cpuset=", current->comm);
- pr_cont_cgroup_name(cgrp);
- pr_cont(" mems_allowed=%*pbl\n",
- nodemask_pr_args(¤t->mems_allowed));
-
- rcu_read_unlock();
-}
-
-/*
- * Collection of memory_pressure is suppressed unless
- * this flag is enabled by writing "1" to the special
- * cpuset file 'memory_pressure_enabled' in the root cpuset.
- */
-
-int cpuset_memory_pressure_enabled __read_mostly;
-
-/**
- * cpuset_memory_pressure_bump - keep stats of per-cpuset reclaims.
- *
- * Keep a running average of the rate of synchronous (direct)
- * page reclaim efforts initiated by tasks in each cpuset.
- *
- * This represents the rate at which some task in the cpuset
- * ran low on memory on all nodes it was allowed to use, and
- * had to enter the kernels page reclaim code in an effort to
- * create more free memory by tossing clean pages or swapping
- * or writing dirty pages.
- *
- * Display to user space in the per-cpuset read-only file
- * "memory_pressure". Value displayed is an integer
- * representing the recent rate of entry into the synchronous
- * (direct) page reclaim by any task attached to the cpuset.
- **/
-
-void __cpuset_memory_pressure_bump(void)
-{
- rcu_read_lock();
- fmeter_markevent(&task_cs(current)->fmeter);
- rcu_read_unlock();
-}
-
-#ifdef CONFIG_PROC_PID_CPUSET
-/*
- * proc_cpuset_show()
- * - Print tasks cpuset path into seq_file.
- * - Used for /proc/<pid>/cpuset.
- * - No need to task_lock(tsk) on this tsk->cpuset reference, as it
- * doesn't really matter if tsk->cpuset changes after we read it,
- * and we take cpuset_mutex, keeping cpuset_attach() from changing it
- * anyway.
- */
-int proc_cpuset_show(struct seq_file *m, struct pid_namespace *ns,
- struct pid *pid, struct task_struct *tsk)
-{
- char *buf;
- struct cgroup_subsys_state *css;
- int retval;
-
- retval = -ENOMEM;
- buf = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!buf)
- goto out;
-
- css = task_get_css(tsk, cpuset_cgrp_id);
- retval = cgroup_path_ns(css->cgroup, buf, PATH_MAX,
- current->nsproxy->cgroup_ns);
- css_put(css);
- if (retval >= PATH_MAX)
- retval = -ENAMETOOLONG;
- if (retval < 0)
- goto out_free;
- seq_puts(m, buf);
- seq_putc(m, '\n');
- retval = 0;
-out_free:
- kfree(buf);
-out:
- return retval;
-}
-#endif /* CONFIG_PROC_PID_CPUSET */
-
-/* Display task mems_allowed in /proc/<pid>/status file. */
-void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task)
-{
- seq_printf(m, "Mems_allowed:\t%*pb\n",
- nodemask_pr_args(&task->mems_allowed));
- seq_printf(m, "Mems_allowed_list:\t%*pbl\n",
- nodemask_pr_args(&task->mems_allowed));
-}
projects / GitHub / LineageOS / android_kernel_motorola_exynos9610.git / commitdiff