+++ /dev/null
-/*
- * zsmalloc memory allocator
- *
- * Copyright (C) 2011 Nitin Gupta
- *
- * This code is released using a dual license strategy: BSD/GPL
- * You can choose the license that better fits your requirements.
- *
- * Released under the terms of 3-clause BSD License
- * Released under the terms of GNU General Public License Version 2.0
- */
-
-
-/*
- * This allocator is designed for use with zcache and zram. Thus, the
- * allocator is supposed to work well under low memory conditions. In
- * particular, it never attempts higher order page allocation which is
- * very likely to fail under memory pressure. On the other hand, if we
- * just use single (0-order) pages, it would suffer from very high
- * fragmentation -- any object of size PAGE_SIZE/2 or larger would occupy
- * an entire page. This was one of the major issues with its predecessor
- * (xvmalloc).
- *
- * To overcome these issues, zsmalloc allocates a bunch of 0-order pages
- * and links them together using various 'struct page' fields. These linked
- * pages act as a single higher-order page i.e. an object can span 0-order
- * page boundaries. The code refers to these linked pages as a single entity
- * called zspage.
- *
- * Following is how we use various fields and flags of underlying
- * struct page(s) to form a zspage.
- *
- * Usage of struct page fields:
- * page->first_page: points to the first component (0-order) page
- * page->index (union with page->freelist): offset of the first object
- * starting in this page. For the first page, this is
- * always 0, so we use this field (aka freelist) to point
- * to the first free object in zspage.
- * page->lru: links together all component pages (except the first page)
- * of a zspage
- *
- * For _first_ page only:
- *
- * page->private (union with page->first_page): refers to the
- * component page after the first page
- * page->freelist: points to the first free object in zspage.
- * Free objects are linked together using in-place
- * metadata.
- * page->objects: maximum number of objects we can store in this
- * zspage (class->zspage_order * PAGE_SIZE / class->size)
- * page->lru: links together first pages of various zspages.
- * Basically forming list of zspages in a fullness group.
- * page->mapping: class index and fullness group of the zspage
- *
- * Usage of struct page flags:
- * PG_private: identifies the first component page
- * PG_private2: identifies the last component page
- *
- */
-
-#ifdef CONFIG_ZSMALLOC_DEBUG
-#define DEBUG
-#endif
-
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/bitops.h>
-#include <linux/errno.h>
-#include <linux/highmem.h>
-#include <linux/init.h>
-#include <linux/string.h>
-#include <linux/slab.h>
-#include <asm/tlbflush.h>
-#include <asm/pgtable.h>
-#include <linux/cpumask.h>
-#include <linux/cpu.h>
-#include <linux/vmalloc.h>
-#include <linux/hardirq.h>
-#include <linux/spinlock.h>
-#include <linux/types.h>
-
-#include "zsmalloc.h"
-
-/*
- * This must be power of 2 and greater than of equal to sizeof(link_free).
- * These two conditions ensure that any 'struct link_free' itself doesn't
- * span more than 1 page which avoids complex case of mapping 2 pages simply
- * to restore link_free pointer values.
- */
-#define ZS_ALIGN 8
-
-/*
- * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
- * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
- */
-#define ZS_MAX_ZSPAGE_ORDER 2
-#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
-
-/*
- * Object location (<PFN>, <obj_idx>) is encoded as
- * as single (void *) handle value.
- *
- * Note that object index <obj_idx> is relative to system
- * page <PFN> it is stored in, so for each sub-page belonging
- * to a zspage, obj_idx starts with 0.
- *
- * This is made more complicated by various memory models and PAE.
- */
-
-#ifndef MAX_PHYSMEM_BITS
-#ifdef CONFIG_HIGHMEM64G
-#define MAX_PHYSMEM_BITS 36
-#else /* !CONFIG_HIGHMEM64G */
-/*
- * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
- * be PAGE_SHIFT
- */
-#define MAX_PHYSMEM_BITS BITS_PER_LONG
-#endif
-#endif
-#define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
-#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS)
-#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
-
-#define MAX(a, b) ((a) >= (b) ? (a) : (b))
-/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
-#define ZS_MIN_ALLOC_SIZE \
- MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
-#define ZS_MAX_ALLOC_SIZE PAGE_SIZE
-
-/*
- * On systems with 4K page size, this gives 254 size classes! There is a
- * trader-off here:
- * - Large number of size classes is potentially wasteful as free page are
- * spread across these classes
- * - Small number of size classes causes large internal fragmentation
- * - Probably its better to use specific size classes (empirically
- * determined). NOTE: all those class sizes must be set as multiple of
- * ZS_ALIGN to make sure link_free itself never has to span 2 pages.
- *
- * ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
- * (reason above)
- */
-#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
-#define ZS_SIZE_CLASSES ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / \
- ZS_SIZE_CLASS_DELTA + 1)
-
-/*
- * We do not maintain any list for completely empty or full pages
- */
-enum fullness_group {
- ZS_ALMOST_FULL,
- ZS_ALMOST_EMPTY,
- _ZS_NR_FULLNESS_GROUPS,
-
- ZS_EMPTY,
- ZS_FULL
-};
-
-/*
- * We assign a page to ZS_ALMOST_EMPTY fullness group when:
- * n <= N / f, where
- * n = number of allocated objects
- * N = total number of objects zspage can store
- * f = 1/fullness_threshold_frac
- *
- * Similarly, we assign zspage to:
- * ZS_ALMOST_FULL when n > N / f
- * ZS_EMPTY when n == 0
- * ZS_FULL when n == N
- *
- * (see: fix_fullness_group())
- */
-static const int fullness_threshold_frac = 4;
-
-struct size_class {
- /*
- * Size of objects stored in this class. Must be multiple
- * of ZS_ALIGN.
- */
- int size;
- unsigned int index;
-
- /* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
- int pages_per_zspage;
-
- spinlock_t lock;
-
- /* stats */
- u64 pages_allocated;
-
- struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
-};
-
-/*
- * Placed within free objects to form a singly linked list.
- * For every zspage, first_page->freelist gives head of this list.
- *
- * This must be power of 2 and less than or equal to ZS_ALIGN
- */
-struct link_free {
- /* Handle of next free chunk (encodes <PFN, obj_idx>) */
- void *next;
-};
-
-struct zs_pool {
- struct size_class size_class[ZS_SIZE_CLASSES];
-
- gfp_t flags; /* allocation flags used when growing pool */
-};
-
-/*
- * A zspage's class index and fullness group
- * are encoded in its (first)page->mapping
- */
-#define CLASS_IDX_BITS 28
-#define FULLNESS_BITS 4
-#define CLASS_IDX_MASK ((1 << CLASS_IDX_BITS) - 1)
-#define FULLNESS_MASK ((1 << FULLNESS_BITS) - 1)
-
-/*
- * By default, zsmalloc uses a copy-based object mapping method to access
- * allocations that span two pages. However, if a particular architecture
- * performs VM mapping faster than copying, then it should be added here
- * so that USE_PGTABLE_MAPPING is defined. This causes zsmalloc to use
- * page table mapping rather than copying for object mapping.
-*/
-#if defined(CONFIG_ARM) && !defined(MODULE)
-#define USE_PGTABLE_MAPPING
-#endif
-
-struct mapping_area {
-#ifdef USE_PGTABLE_MAPPING
- struct vm_struct *vm; /* vm area for mapping object that span pages */
-#else
- char *vm_buf; /* copy buffer for objects that span pages */
-#endif
- char *vm_addr; /* address of kmap_atomic()'ed pages */
- enum zs_mapmode vm_mm; /* mapping mode */
-};
-
-
-/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
-static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
-
-static int is_first_page(struct page *page)
-{
- return PagePrivate(page);
-}
-
-static int is_last_page(struct page *page)
-{
- return PagePrivate2(page);
-}
-
-static void get_zspage_mapping(struct page *page, unsigned int *class_idx,
- enum fullness_group *fullness)
-{
- unsigned long m;
- BUG_ON(!is_first_page(page));
-
- m = (unsigned long)page->mapping;
- *fullness = m & FULLNESS_MASK;
- *class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
-}
-
-static void set_zspage_mapping(struct page *page, unsigned int class_idx,
- enum fullness_group fullness)
-{
- unsigned long m;
- BUG_ON(!is_first_page(page));
-
- m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
- (fullness & FULLNESS_MASK);
- page->mapping = (struct address_space *)m;
-}
-
-static int get_size_class_index(int size)
-{
- int idx = 0;
-
- if (likely(size > ZS_MIN_ALLOC_SIZE))
- idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
- ZS_SIZE_CLASS_DELTA);
-
- return idx;
-}
-
-static enum fullness_group get_fullness_group(struct page *page)
-{
- int inuse, max_objects;
- enum fullness_group fg;
- BUG_ON(!is_first_page(page));
-
- inuse = page->inuse;
- max_objects = page->objects;
-
- if (inuse == 0)
- fg = ZS_EMPTY;
- else if (inuse == max_objects)
- fg = ZS_FULL;
- else if (inuse <= max_objects / fullness_threshold_frac)
- fg = ZS_ALMOST_EMPTY;
- else
- fg = ZS_ALMOST_FULL;
-
- return fg;
-}
-
-static void insert_zspage(struct page *page, struct size_class *class,
- enum fullness_group fullness)
-{
- struct page **head;
-
- BUG_ON(!is_first_page(page));
-
- if (fullness >= _ZS_NR_FULLNESS_GROUPS)
- return;
-
- head = &class->fullness_list[fullness];
- if (*head)
- list_add_tail(&page->lru, &(*head)->lru);
-
- *head = page;
-}
-
-static void remove_zspage(struct page *page, struct size_class *class,
- enum fullness_group fullness)
-{
- struct page **head;
-
- BUG_ON(!is_first_page(page));
-
- if (fullness >= _ZS_NR_FULLNESS_GROUPS)
- return;
-
- head = &class->fullness_list[fullness];
- BUG_ON(!*head);
- if (list_empty(&(*head)->lru))
- *head = NULL;
- else if (*head == page)
- *head = (struct page *)list_entry((*head)->lru.next,
- struct page, lru);
-
- list_del_init(&page->lru);
-}
-
-static enum fullness_group fix_fullness_group(struct zs_pool *pool,
- struct page *page)
-{
- int class_idx;
- struct size_class *class;
- enum fullness_group currfg, newfg;
-
- BUG_ON(!is_first_page(page));
-
- get_zspage_mapping(page, &class_idx, &currfg);
- newfg = get_fullness_group(page);
- if (newfg == currfg)
- goto out;
-
- class = &pool->size_class[class_idx];
- remove_zspage(page, class, currfg);
- insert_zspage(page, class, newfg);
- set_zspage_mapping(page, class_idx, newfg);
-
-out:
- return newfg;
-}
-
-/*
- * We have to decide on how many pages to link together
- * to form a zspage for each size class. This is important
- * to reduce wastage due to unusable space left at end of
- * each zspage which is given as:
- * wastage = Zp - Zp % size_class
- * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
- *
- * For example, for size class of 3/8 * PAGE_SIZE, we should
- * link together 3 PAGE_SIZE sized pages to form a zspage
- * since then we can perfectly fit in 8 such objects.
- */
-static int get_pages_per_zspage(int class_size)
-{
- int i, max_usedpc = 0;
- /* zspage order which gives maximum used size per KB */
- int max_usedpc_order = 1;
-
- for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
- int zspage_size;
- int waste, usedpc;
-
- zspage_size = i * PAGE_SIZE;
- waste = zspage_size % class_size;
- usedpc = (zspage_size - waste) * 100 / zspage_size;
-
- if (usedpc > max_usedpc) {
- max_usedpc = usedpc;
- max_usedpc_order = i;
- }
- }
-
- return max_usedpc_order;
-}
-
-/*
- * A single 'zspage' is composed of many system pages which are
- * linked together using fields in struct page. This function finds
- * the first/head page, given any component page of a zspage.
- */
-static struct page *get_first_page(struct page *page)
-{
- if (is_first_page(page))
- return page;
- else
- return page->first_page;
-}
-
-static struct page *get_next_page(struct page *page)
-{
- struct page *next;
-
- if (is_last_page(page))
- next = NULL;
- else if (is_first_page(page))
- next = (struct page *)page->private;
- else
- next = list_entry(page->lru.next, struct page, lru);
-
- return next;
-}
-
-/*
- * Encode <page, obj_idx> as a single handle value.
- * On hardware platforms with physical memory starting at 0x0 the pfn
- * could be 0 so we ensure that the handle will never be 0 by adjusting the
- * encoded obj_idx value before encoding.
- */
-static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
-{
- unsigned long handle;
-
- if (!page) {
- BUG_ON(obj_idx);
- return NULL;
- }
-
- handle = page_to_pfn(page) << OBJ_INDEX_BITS;
- handle |= ((obj_idx + 1) & OBJ_INDEX_MASK);
-
- return (void *)handle;
-}
-
-/*
- * Decode <page, obj_idx> pair from the given object handle. We adjust the
- * decoded obj_idx back to its original value since it was adjusted in
- * obj_location_to_handle().
- */
-static void obj_handle_to_location(unsigned long handle, struct page **page,
- unsigned long *obj_idx)
-{
- *page = pfn_to_page(handle >> OBJ_INDEX_BITS);
- *obj_idx = (handle & OBJ_INDEX_MASK) - 1;
-}
-
-static unsigned long obj_idx_to_offset(struct page *page,
- unsigned long obj_idx, int class_size)
-{
- unsigned long off = 0;
-
- if (!is_first_page(page))
- off = page->index;
-
- return off + obj_idx * class_size;
-}
-
-static void reset_page(struct page *page)
-{
- clear_bit(PG_private, &page->flags);
- clear_bit(PG_private_2, &page->flags);
- set_page_private(page, 0);
- page->mapping = NULL;
- page->freelist = NULL;
- page_mapcount_reset(page);
-}
-
-static void free_zspage(struct page *first_page)
-{
- struct page *nextp, *tmp, *head_extra;
-
- BUG_ON(!is_first_page(first_page));
- BUG_ON(first_page->inuse);
-
- head_extra = (struct page *)page_private(first_page);
-
- reset_page(first_page);
- __free_page(first_page);
-
- /* zspage with only 1 system page */
- if (!head_extra)
- return;
-
- list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
- list_del(&nextp->lru);
- reset_page(nextp);
- __free_page(nextp);
- }
- reset_page(head_extra);
- __free_page(head_extra);
-}
-
-/* Initialize a newly allocated zspage */
-static void init_zspage(struct page *first_page, struct size_class *class)
-{
- unsigned long off = 0;
- struct page *page = first_page;
-
- BUG_ON(!is_first_page(first_page));
- while (page) {
- struct page *next_page;
- struct link_free *link;
- unsigned int i, objs_on_page;
-
- /*
- * page->index stores offset of first object starting
- * in the page. For the first page, this is always 0,
- * so we use first_page->index (aka ->freelist) to store
- * head of corresponding zspage's freelist.
- */
- if (page != first_page)
- page->index = off;
-
- link = (struct link_free *)kmap_atomic(page) +
- off / sizeof(*link);
- objs_on_page = (PAGE_SIZE - off) / class->size;
-
- for (i = 1; i <= objs_on_page; i++) {
- off += class->size;
- if (off < PAGE_SIZE) {
- link->next = obj_location_to_handle(page, i);
- link += class->size / sizeof(*link);
- }
- }
-
- /*
- * We now come to the last (full or partial) object on this
- * page, which must point to the first object on the next
- * page (if present)
- */
- next_page = get_next_page(page);
- link->next = obj_location_to_handle(next_page, 0);
- kunmap_atomic(link);
- page = next_page;
- off = (off + class->size) % PAGE_SIZE;
- }
-}
-
-/*
- * Allocate a zspage for the given size class
- */
-static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
-{
- int i, error;
- struct page *first_page = NULL, *uninitialized_var(prev_page);
-
- /*
- * Allocate individual pages and link them together as:
- * 1. first page->private = first sub-page
- * 2. all sub-pages are linked together using page->lru
- * 3. each sub-page is linked to the first page using page->first_page
- *
- * For each size class, First/Head pages are linked together using
- * page->lru. Also, we set PG_private to identify the first page
- * (i.e. no other sub-page has this flag set) and PG_private_2 to
- * identify the last page.
- */
- error = -ENOMEM;
- for (i = 0; i < class->pages_per_zspage; i++) {
- struct page *page;
-
- page = alloc_page(flags);
- if (!page)
- goto cleanup;
-
- INIT_LIST_HEAD(&page->lru);
- if (i == 0) { /* first page */
- SetPagePrivate(page);
- set_page_private(page, 0);
- first_page = page;
- first_page->inuse = 0;
- }
- if (i == 1)
- first_page->private = (unsigned long)page;
- if (i >= 1)
- page->first_page = first_page;
- if (i >= 2)
- list_add(&page->lru, &prev_page->lru);
- if (i == class->pages_per_zspage - 1) /* last page */
- SetPagePrivate2(page);
- prev_page = page;
- }
-
- init_zspage(first_page, class);
-
- first_page->freelist = obj_location_to_handle(first_page, 0);
- /* Maximum number of objects we can store in this zspage */
- first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
-
- error = 0; /* Success */
-
-cleanup:
- if (unlikely(error) && first_page) {
- free_zspage(first_page);
- first_page = NULL;
- }
-
- return first_page;
-}
-
-static struct page *find_get_zspage(struct size_class *class)
-{
- int i;
- struct page *page;
-
- for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
- page = class->fullness_list[i];
- if (page)
- break;
- }
-
- return page;
-}
-
-#ifdef USE_PGTABLE_MAPPING
-static inline int __zs_cpu_up(struct mapping_area *area)
-{
- /*
- * Make sure we don't leak memory if a cpu UP notification
- * and zs_init() race and both call zs_cpu_up() on the same cpu
- */
- if (area->vm)
- return 0;
- area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
- if (!area->vm)
- return -ENOMEM;
- return 0;
-}
-
-static inline void __zs_cpu_down(struct mapping_area *area)
-{
- if (area->vm)
- free_vm_area(area->vm);
- area->vm = NULL;
-}
-
-static inline void *__zs_map_object(struct mapping_area *area,
- struct page *pages[2], int off, int size)
-{
- BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, &pages));
- area->vm_addr = area->vm->addr;
- return area->vm_addr + off;
-}
-
-static inline void __zs_unmap_object(struct mapping_area *area,
- struct page *pages[2], int off, int size)
-{
- unsigned long addr = (unsigned long)area->vm_addr;
-
- unmap_kernel_range(addr, PAGE_SIZE * 2);
-}
-
-#else /* USE_PGTABLE_MAPPING */
-
-static inline int __zs_cpu_up(struct mapping_area *area)
-{
- /*
- * Make sure we don't leak memory if a cpu UP notification
- * and zs_init() race and both call zs_cpu_up() on the same cpu
- */
- if (area->vm_buf)
- return 0;
- area->vm_buf = (char *)__get_free_page(GFP_KERNEL);
- if (!area->vm_buf)
- return -ENOMEM;
- return 0;
-}
-
-static inline void __zs_cpu_down(struct mapping_area *area)
-{
- if (area->vm_buf)
- free_page((unsigned long)area->vm_buf);
- area->vm_buf = NULL;
-}
-
-static void *__zs_map_object(struct mapping_area *area,
- struct page *pages[2], int off, int size)
-{
- int sizes[2];
- void *addr;
- char *buf = area->vm_buf;
-
- /* disable page faults to match kmap_atomic() return conditions */
- pagefault_disable();
-
- /* no read fastpath */
- if (area->vm_mm == ZS_MM_WO)
- goto out;
-
- sizes[0] = PAGE_SIZE - off;
- sizes[1] = size - sizes[0];
-
- /* copy object to per-cpu buffer */
- addr = kmap_atomic(pages[0]);
- memcpy(buf, addr + off, sizes[0]);
- kunmap_atomic(addr);
- addr = kmap_atomic(pages[1]);
- memcpy(buf + sizes[0], addr, sizes[1]);
- kunmap_atomic(addr);
-out:
- return area->vm_buf;
-}
-
-static void __zs_unmap_object(struct mapping_area *area,
- struct page *pages[2], int off, int size)
-{
- int sizes[2];
- void *addr;
- char *buf = area->vm_buf;
-
- /* no write fastpath */
- if (area->vm_mm == ZS_MM_RO)
- goto out;
-
- sizes[0] = PAGE_SIZE - off;
- sizes[1] = size - sizes[0];
-
- /* copy per-cpu buffer to object */
- addr = kmap_atomic(pages[0]);
- memcpy(addr + off, buf, sizes[0]);
- kunmap_atomic(addr);
- addr = kmap_atomic(pages[1]);
- memcpy(addr, buf + sizes[0], sizes[1]);
- kunmap_atomic(addr);
-
-out:
- /* enable page faults to match kunmap_atomic() return conditions */
- pagefault_enable();
-}
-
-#endif /* USE_PGTABLE_MAPPING */
-
-static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
- void *pcpu)
-{
- int ret, cpu = (long)pcpu;
- struct mapping_area *area;
-
- switch (action) {
- case CPU_UP_PREPARE:
- area = &per_cpu(zs_map_area, cpu);
- ret = __zs_cpu_up(area);
- if (ret)
- return notifier_from_errno(ret);
- break;
- case CPU_DEAD:
- case CPU_UP_CANCELED:
- area = &per_cpu(zs_map_area, cpu);
- __zs_cpu_down(area);
- break;
- }
-
- return NOTIFY_OK;
-}
-
-static struct notifier_block zs_cpu_nb = {
- .notifier_call = zs_cpu_notifier
-};
-
-static void zs_exit(void)
-{
- int cpu;
-
- for_each_online_cpu(cpu)
- zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
- unregister_cpu_notifier(&zs_cpu_nb);
-}
-
-static int zs_init(void)
-{
- int cpu, ret;
-
- register_cpu_notifier(&zs_cpu_nb);
- for_each_online_cpu(cpu) {
- ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
- if (notifier_to_errno(ret))
- goto fail;
- }
- return 0;
-fail:
- zs_exit();
- return notifier_to_errno(ret);
-}
-
-/**
- * zs_create_pool - Creates an allocation pool to work from.
- * @flags: allocation flags used to allocate pool metadata
- *
- * This function must be called before anything when using
- * the zsmalloc allocator.
- *
- * On success, a pointer to the newly created pool is returned,
- * otherwise NULL.
- */
-struct zs_pool *zs_create_pool(gfp_t flags)
-{
- int i, ovhd_size;
- struct zs_pool *pool;
-
- ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
- pool = kzalloc(ovhd_size, GFP_KERNEL);
- if (!pool)
- return NULL;
-
- for (i = 0; i < ZS_SIZE_CLASSES; i++) {
- int size;
- struct size_class *class;
-
- size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
- if (size > ZS_MAX_ALLOC_SIZE)
- size = ZS_MAX_ALLOC_SIZE;
-
- class = &pool->size_class[i];
- class->size = size;
- class->index = i;
- spin_lock_init(&class->lock);
- class->pages_per_zspage = get_pages_per_zspage(size);
-
- }
-
- pool->flags = flags;
-
- return pool;
-}
-EXPORT_SYMBOL_GPL(zs_create_pool);
-
-void zs_destroy_pool(struct zs_pool *pool)
-{
- int i;
-
- for (i = 0; i < ZS_SIZE_CLASSES; i++) {
- int fg;
- struct size_class *class = &pool->size_class[i];
-
- for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
- if (class->fullness_list[fg]) {
- pr_info("Freeing non-empty class with size "
- "%db, fullness group %d\n",
- class->size, fg);
- }
- }
- }
- kfree(pool);
-}
-EXPORT_SYMBOL_GPL(zs_destroy_pool);
-
-/**
- * zs_malloc - Allocate block of given size from pool.
- * @pool: pool to allocate from
- * @size: size of block to allocate
- *
- * On success, handle to the allocated object is returned,
- * otherwise 0.
- * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
- */
-unsigned long zs_malloc(struct zs_pool *pool, size_t size)
-{
- unsigned long obj;
- struct link_free *link;
- int class_idx;
- struct size_class *class;
-
- struct page *first_page, *m_page;
- unsigned long m_objidx, m_offset;
-
- if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
- return 0;
-
- class_idx = get_size_class_index(size);
- class = &pool->size_class[class_idx];
- BUG_ON(class_idx != class->index);
-
- spin_lock(&class->lock);
- first_page = find_get_zspage(class);
-
- if (!first_page) {
- spin_unlock(&class->lock);
- first_page = alloc_zspage(class, pool->flags);
- if (unlikely(!first_page))
- return 0;
-
- set_zspage_mapping(first_page, class->index, ZS_EMPTY);
- spin_lock(&class->lock);
- class->pages_allocated += class->pages_per_zspage;
- }
-
- obj = (unsigned long)first_page->freelist;
- obj_handle_to_location(obj, &m_page, &m_objidx);
- m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
-
- link = (struct link_free *)kmap_atomic(m_page) +
- m_offset / sizeof(*link);
- first_page->freelist = link->next;
- memset(link, POISON_INUSE, sizeof(*link));
- kunmap_atomic(link);
-
- first_page->inuse++;
- /* Now move the zspage to another fullness group, if required */
- fix_fullness_group(pool, first_page);
- spin_unlock(&class->lock);
-
- return obj;
-}
-EXPORT_SYMBOL_GPL(zs_malloc);
-
-void zs_free(struct zs_pool *pool, unsigned long obj)
-{
- struct link_free *link;
- struct page *first_page, *f_page;
- unsigned long f_objidx, f_offset;
-
- int class_idx;
- struct size_class *class;
- enum fullness_group fullness;
-
- if (unlikely(!obj))
- return;
-
- obj_handle_to_location(obj, &f_page, &f_objidx);
- first_page = get_first_page(f_page);
-
- get_zspage_mapping(first_page, &class_idx, &fullness);
- class = &pool->size_class[class_idx];
- f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
-
- spin_lock(&class->lock);
-
- /* Insert this object in containing zspage's freelist */
- link = (struct link_free *)((unsigned char *)kmap_atomic(f_page)
- + f_offset);
- link->next = first_page->freelist;
- kunmap_atomic(link);
- first_page->freelist = (void *)obj;
-
- first_page->inuse--;
- fullness = fix_fullness_group(pool, first_page);
-
- if (fullness == ZS_EMPTY)
- class->pages_allocated -= class->pages_per_zspage;
-
- spin_unlock(&class->lock);
-
- if (fullness == ZS_EMPTY)
- free_zspage(first_page);
-}
-EXPORT_SYMBOL_GPL(zs_free);
-
-/**
- * zs_map_object - get address of allocated object from handle.
- * @pool: pool from which the object was allocated
- * @handle: handle returned from zs_malloc
- *
- * Before using an object allocated from zs_malloc, it must be mapped using
- * this function. When done with the object, it must be unmapped using
- * zs_unmap_object.
- *
- * Only one object can be mapped per cpu at a time. There is no protection
- * against nested mappings.
- *
- * This function returns with preemption and page faults disabled.
-*/
-void *zs_map_object(struct zs_pool *pool, unsigned long handle,
- enum zs_mapmode mm)
-{
- struct page *page;
- unsigned long obj_idx, off;
-
- unsigned int class_idx;
- enum fullness_group fg;
- struct size_class *class;
- struct mapping_area *area;
- struct page *pages[2];
-
- BUG_ON(!handle);
-
- /*
- * Because we use per-cpu mapping areas shared among the
- * pools/users, we can't allow mapping in interrupt context
- * because it can corrupt another users mappings.
- */
- BUG_ON(in_interrupt());
-
- obj_handle_to_location(handle, &page, &obj_idx);
- get_zspage_mapping(get_first_page(page), &class_idx, &fg);
- class = &pool->size_class[class_idx];
- off = obj_idx_to_offset(page, obj_idx, class->size);
-
- area = &get_cpu_var(zs_map_area);
- area->vm_mm = mm;
- if (off + class->size <= PAGE_SIZE) {
- /* this object is contained entirely within a page */
- area->vm_addr = kmap_atomic(page);
- return area->vm_addr + off;
- }
-
- /* this object spans two pages */
- pages[0] = page;
- pages[1] = get_next_page(page);
- BUG_ON(!pages[1]);
-
- return __zs_map_object(area, pages, off, class->size);
-}
-EXPORT_SYMBOL_GPL(zs_map_object);
-
-void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
-{
- struct page *page;
- unsigned long obj_idx, off;
-
- unsigned int class_idx;
- enum fullness_group fg;
- struct size_class *class;
- struct mapping_area *area;
-
- BUG_ON(!handle);
-
- obj_handle_to_location(handle, &page, &obj_idx);
- get_zspage_mapping(get_first_page(page), &class_idx, &fg);
- class = &pool->size_class[class_idx];
- off = obj_idx_to_offset(page, obj_idx, class->size);
-
- area = &__get_cpu_var(zs_map_area);
- if (off + class->size <= PAGE_SIZE)
- kunmap_atomic(area->vm_addr);
- else {
- struct page *pages[2];
-
- pages[0] = page;
- pages[1] = get_next_page(page);
- BUG_ON(!pages[1]);
-
- __zs_unmap_object(area, pages, off, class->size);
- }
- put_cpu_var(zs_map_area);
-}
-EXPORT_SYMBOL_GPL(zs_unmap_object);
-
-u64 zs_get_total_size_bytes(struct zs_pool *pool)
-{
- int i;
- u64 npages = 0;
-
- for (i = 0; i < ZS_SIZE_CLASSES; i++)
- npages += pool->size_class[i].pages_allocated;
-
- return npages << PAGE_SHIFT;
-}
-EXPORT_SYMBOL_GPL(zs_get_total_size_bytes);
-
-module_init(zs_init);
-module_exit(zs_exit);
-
-MODULE_LICENSE("Dual BSD/GPL");
-MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");
*/
/*
- * This allocator is designed for use with zram. Thus, the allocator is
- * supposed to work well under low memory conditions. In particular, it
- * never attempts higher order page allocation which is very likely to
- * fail under memory pressure. On the other hand, if we just use single
- * (0-order) pages, it would suffer from very high fragmentation --
- * any object of size PAGE_SIZE/2 or larger would occupy an entire page.
- * This was one of the major issues with its predecessor (xvmalloc).
- *
- * To overcome these issues, zsmalloc allocates a bunch of 0-order pages
- * and links them together using various 'struct page' fields. These linked
- * pages act as a single higher-order page i.e. an object can span 0-order
- * page boundaries. The code refers to these linked pages as a single entity
- * called zspage.
- *
- * For simplicity, zsmalloc can only allocate objects of size up to PAGE_SIZE
- * since this satisfies the requirements of all its current users (in the
- * worst case, page is incompressible and is thus stored "as-is" i.e. in
- * uncompressed form). For allocation requests larger than this size, failure
- * is returned (see zs_malloc).
- *
- * Additionally, zs_malloc() does not return a dereferenceable pointer.
- * Instead, it returns an opaque handle (unsigned long) which encodes actual
- * location of the allocated object. The reason for this indirection is that
- * zsmalloc does not keep zspages permanently mapped since that would cause
- * issues on 32-bit systems where the VA region for kernel space mappings
- * is very small. So, before using the allocating memory, the object has to
- * be mapped using zs_map_object() to get a usable pointer and subsequently
- * unmapped using zs_unmap_object().
- *
* Following is how we use various fields and flags of underlying
* struct page(s) to form a zspage.
*
*
* page->private (union with page->first_page): refers to the
* component page after the first page
+ * If the page is first_page for huge object, it stores handle.
+ * Look at size_class->huge.
* page->freelist: points to the first free object in zspage.
* Free objects are linked together using in-place
* metadata.
#include <linux/module.h>
#include <linux/kernel.h>
+#include <linux/sched.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/highmem.h>
#include <linux/hardirq.h>
#include <linux/spinlock.h>
#include <linux/types.h>
+#include <linux/debugfs.h>
#include <linux/zsmalloc.h>
#include <linux/zpool.h>
#define ZS_MAX_ZSPAGE_ORDER 2
#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
+#define ZS_HANDLE_SIZE (sizeof(unsigned long))
+
/*
* Object location (<PFN>, <obj_idx>) is encoded as
* as single (unsigned long) handle value.
#endif
#endif
#define _PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT)
-#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS)
+
+/*
+ * Memory for allocating for handle keeps object position by
+ * encoding <page, obj_idx> and the encoded value has a room
+ * in least bit(ie, look at obj_to_location).
+ * We use the bit to synchronize between object access by
+ * user and migration.
+ */
+#define HANDLE_PIN_BIT 0
+
+/*
+ * Head in allocated object should have OBJ_ALLOCATED_TAG
+ * to identify the object was allocated or not.
+ * It's okay to add the status bit in the least bit because
+ * header keeps handle which is 4byte-aligned address so we
+ * have room for two bit at least.
+ */
+#define OBJ_ALLOCATED_TAG 1
+#define OBJ_TAG_BITS 1
+#define OBJ_INDEX_BITS (BITS_PER_LONG - _PFN_BITS - OBJ_TAG_BITS)
#define OBJ_INDEX_MASK ((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
#define MAX(a, b) ((a) >= (b) ? (a) : (b))
/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
#define ZS_MIN_ALLOC_SIZE \
MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
+/* each chunk includes extra space to keep handle */
#define ZS_MAX_ALLOC_SIZE PAGE_SIZE
/*
* (reason above)
*/
#define ZS_SIZE_CLASS_DELTA (PAGE_SIZE >> 8)
-#define ZS_SIZE_CLASSES ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / \
- ZS_SIZE_CLASS_DELTA + 1)
/*
- * We do not maintain any list for completely empty zspages,
- * since a zspage is freed when it becomes empty.
+ * We do not maintain any list for completely empty or full pages
*/
enum fullness_group {
ZS_ALMOST_FULL,
ZS_ALMOST_EMPTY,
- ZS_FULL,
-
_ZS_NR_FULLNESS_GROUPS,
ZS_EMPTY,
- ZS_RECLAIM
+ ZS_FULL
+};
+
+enum zs_stat_type {
+ OBJ_ALLOCATED,
+ OBJ_USED,
+ CLASS_ALMOST_FULL,
+ CLASS_ALMOST_EMPTY,
+ NR_ZS_STAT_TYPE,
+};
+
+#ifdef CONFIG_ZSMALLOC_STAT
+
+static struct dentry *zs_stat_root;
+
+struct zs_size_stat {
+ unsigned long objs[NR_ZS_STAT_TYPE];
};
-#define _ZS_NR_AVAILABLE_FULLNESS_GROUPS ZS_FULL
+
+#endif
+
+/*
+ * number of size_classes
+ */
+static int zs_size_classes;
/*
* We assign a page to ZS_ALMOST_EMPTY fullness group when:
/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
int pages_per_zspage;
+ /* huge object: pages_per_zspage == 1 && maxobj_per_zspage == 1 */
+ bool huge;
+
+#ifdef CONFIG_ZSMALLOC_STAT
+ struct zs_size_stat stats;
+#endif
spinlock_t lock;
* This must be power of 2 and less than or equal to ZS_ALIGN
*/
struct link_free {
- /* Handle of next free chunk (encodes <PFN, obj_idx>) */
- void *next;
+ union {
+ /*
+ * Position of next free chunk (encodes <PFN, obj_idx>)
+ * It's valid for non-allocated object
+ */
+ void *next;
+ /*
+ * Handle of allocated object.
+ */
+ unsigned long handle;
+ };
};
struct zs_pool {
- struct size_class *size_class[ZS_SIZE_CLASSES];
+ char *name;
+
+ struct size_class **size_class;
+ struct kmem_cache *handle_cachep;
gfp_t flags; /* allocation flags used when growing pool */
atomic_long_t pages_allocated;
- struct zs_ops *ops;
+#ifdef CONFIG_ZSMALLOC_STAT
+ struct dentry *stat_dentry;
+#endif
};
/*
#endif
char *vm_addr; /* address of kmap_atomic()'ed pages */
enum zs_mapmode vm_mm; /* mapping mode */
+ bool huge;
};
-/* atomic counter indicating which class/fg to reclaim from */
-static atomic_t lru_class_fg;
-/* specific order of fg we want to reclaim from */
-static enum fullness_group lru_fg[] = {
- ZS_ALMOST_EMPTY,
- ZS_ALMOST_FULL,
- ZS_FULL
-};
-#define _ZS_NR_LRU_CLASS_FG (ZS_SIZE_CLASSES * ARRAY_SIZE(lru_fg))
+static int create_handle_cache(struct zs_pool *pool)
+{
+ pool->handle_cachep = kmem_cache_create("zs_handle", ZS_HANDLE_SIZE,
+ 0, 0, NULL);
+ return pool->handle_cachep ? 0 : 1;
+}
-/* zpool driver */
+static void destroy_handle_cache(struct zs_pool *pool)
+{
+ if (pool->handle_cachep)
+ kmem_cache_destroy(pool->handle_cachep);
+}
-#ifdef CONFIG_ZPOOL
+static unsigned long alloc_handle(struct zs_pool *pool)
+{
+ return (unsigned long)kmem_cache_alloc(pool->handle_cachep,
+ pool->flags & ~__GFP_HIGHMEM);
+}
-static int zs_zpool_evict(struct zs_pool *pool, unsigned long handle)
+static void free_handle(struct zs_pool *pool, unsigned long handle)
{
- return zpool_evict(pool, handle);
+ kmem_cache_free(pool->handle_cachep, (void *)handle);
}
-static struct zs_ops zs_zpool_ops = {
- .evict = zs_zpool_evict
-};
+static void record_obj(unsigned long handle, unsigned long obj)
+{
+ /*
+ * lsb of @obj represents handle lock while other bits
+ * represent object value the handle is pointing so
+ * updating shouldn't do store tearing.
+ */
+ WRITE_ONCE(*(unsigned long *)handle, obj);
+}
+
+/* zpool driver */
+
+#ifdef CONFIG_ZPOOL
-static void *zs_zpool_create(gfp_t gfp, struct zpool_ops *zpool_ops)
+static void *zs_zpool_create(char *name, gfp_t gfp, struct zpool_ops *zpool_ops)
{
- return zs_create_pool(gfp, &zs_zpool_ops);
+ return zs_create_pool(name, gfp);
}
static void zs_zpool_destroy(void *pool)
static int zs_zpool_shrink(void *pool, unsigned int pages,
unsigned int *reclaimed)
{
- int total = 0, ret = 0;
-
- while (total < pages) {
- ret = zs_shrink(pool);
- WARN_ON(!ret);
- if (ret <= 0)
- break;
- total += ret;
- ret = 0;
- }
-
- if (reclaimed)
- *reclaimed = total;
- return ret;
+ return -EINVAL;
}
static void *zs_zpool_map(void *pool, unsigned long handle,
MODULE_ALIAS("zpool-zsmalloc");
#endif /* CONFIG_ZPOOL */
+static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
+{
+ return pages_per_zspage * PAGE_SIZE / size;
+}
+
/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
ZS_SIZE_CLASS_DELTA);
- return idx;
+ return min(zs_size_classes - 1, idx);
+}
+
+#ifdef CONFIG_ZSMALLOC_STAT
+
+static inline void zs_stat_inc(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+ class->stats.objs[type] += cnt;
+}
+
+static inline void zs_stat_dec(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+ class->stats.objs[type] -= cnt;
+}
+
+static inline unsigned long zs_stat_get(struct size_class *class,
+ enum zs_stat_type type)
+{
+ return class->stats.objs[type];
+}
+
+static int __init zs_stat_init(void)
+{
+ if (!debugfs_initialized())
+ return -ENODEV;
+
+ zs_stat_root = debugfs_create_dir("zsmalloc", NULL);
+ if (!zs_stat_root)
+ return -ENOMEM;
+
+ return 0;
+}
+
+static void __exit zs_stat_exit(void)
+{
+ debugfs_remove_recursive(zs_stat_root);
+}
+
+static int zs_stats_size_show(struct seq_file *s, void *v)
+{
+ int i;
+ struct zs_pool *pool = s->private;
+ struct size_class *class;
+ int objs_per_zspage;
+ unsigned long class_almost_full, class_almost_empty;
+ unsigned long obj_allocated, obj_used, pages_used;
+ unsigned long total_class_almost_full = 0, total_class_almost_empty = 0;
+ unsigned long total_objs = 0, total_used_objs = 0, total_pages = 0;
+
+ seq_printf(s, " %5s %5s %11s %12s %13s %10s %10s %16s\n",
+ "class", "size", "almost_full", "almost_empty",
+ "obj_allocated", "obj_used", "pages_used",
+ "pages_per_zspage");
+
+ for (i = 0; i < zs_size_classes; i++) {
+ class = pool->size_class[i];
+
+ if (class->index != i)
+ continue;
+
+ spin_lock(&class->lock);
+ class_almost_full = zs_stat_get(class, CLASS_ALMOST_FULL);
+ class_almost_empty = zs_stat_get(class, CLASS_ALMOST_EMPTY);
+ obj_allocated = zs_stat_get(class, OBJ_ALLOCATED);
+ obj_used = zs_stat_get(class, OBJ_USED);
+ spin_unlock(&class->lock);
+
+ objs_per_zspage = get_maxobj_per_zspage(class->size,
+ class->pages_per_zspage);
+ pages_used = obj_allocated / objs_per_zspage *
+ class->pages_per_zspage;
+
+ seq_printf(s, " %5u %5u %11lu %12lu %13lu %10lu %10lu %16d\n",
+ i, class->size, class_almost_full, class_almost_empty,
+ obj_allocated, obj_used, pages_used,
+ class->pages_per_zspage);
+
+ total_class_almost_full += class_almost_full;
+ total_class_almost_empty += class_almost_empty;
+ total_objs += obj_allocated;
+ total_used_objs += obj_used;
+ total_pages += pages_used;
+ }
+
+ seq_puts(s, "\n");
+ seq_printf(s, " %5s %5s %11lu %12lu %13lu %10lu %10lu\n",
+ "Total", "", total_class_almost_full,
+ total_class_almost_empty, total_objs,
+ total_used_objs, total_pages);
+
+ return 0;
+}
+
+static int zs_stats_size_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, zs_stats_size_show, inode->i_private);
+}
+
+static const struct file_operations zs_stat_size_ops = {
+ .open = zs_stats_size_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
+
+static int zs_pool_stat_create(char *name, struct zs_pool *pool)
+{
+ struct dentry *entry;
+
+ if (!zs_stat_root)
+ return -ENODEV;
+
+ entry = debugfs_create_dir(name, zs_stat_root);
+ if (!entry) {
+ pr_warn("debugfs dir <%s> creation failed\n", name);
+ return -ENOMEM;
+ }
+ pool->stat_dentry = entry;
+
+ entry = debugfs_create_file("classes", S_IFREG | S_IRUGO,
+ pool->stat_dentry, pool, &zs_stat_size_ops);
+ if (!entry) {
+ pr_warn("%s: debugfs file entry <%s> creation failed\n",
+ name, "classes");
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static void zs_pool_stat_destroy(struct zs_pool *pool)
+{
+ debugfs_remove_recursive(pool->stat_dentry);
+}
+
+#else /* CONFIG_ZSMALLOC_STAT */
+
+static inline void zs_stat_inc(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+}
+
+static inline void zs_stat_dec(struct size_class *class,
+ enum zs_stat_type type, unsigned long cnt)
+{
+}
+
+static inline unsigned long zs_stat_get(struct size_class *class,
+ enum zs_stat_type type)
+{
+ return 0;
+}
+
+static int __init zs_stat_init(void)
+{
+ return 0;
+}
+
+static void __exit zs_stat_exit(void)
+{
+}
+
+static inline int zs_pool_stat_create(char *name, struct zs_pool *pool)
+{
+ return 0;
+}
+
+static inline void zs_pool_stat_destroy(struct zs_pool *pool)
+{
}
+#endif
+
+
/*
* For each size class, zspages are divided into different groups
* depending on how "full" they are. This was done so that we could
fg = ZS_EMPTY;
else if (inuse == max_objects)
fg = ZS_FULL;
- else if (inuse <= max_objects / fullness_threshold_frac)
+ else if (inuse <= 3 * max_objects / fullness_threshold_frac)
fg = ZS_ALMOST_EMPTY;
else
fg = ZS_ALMOST_FULL;
list_add_tail(&page->lru, &(*head)->lru);
*head = page;
+ zs_stat_inc(class, fullness == ZS_ALMOST_EMPTY ?
+ CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
}
/*
struct page, lru);
list_del_init(&page->lru);
+ zs_stat_dec(class, fullness == ZS_ALMOST_EMPTY ?
+ CLASS_ALMOST_EMPTY : CLASS_ALMOST_FULL, 1);
}
/*
* page from the freelist of the old fullness group to that of the new
* fullness group.
*/
-static enum fullness_group fix_fullness_group(struct zs_pool *pool,
+static enum fullness_group fix_fullness_group(struct size_class *class,
struct page *page)
{
int class_idx;
- struct size_class *class;
enum fullness_group currfg, newfg;
BUG_ON(!is_first_page(page));
get_zspage_mapping(page, &class_idx, &currfg);
- class = pool->size_class[class_idx];
newfg = get_fullness_group(page);
- /* Need to do this even if currfg == newfg, to update lru */
+ if (newfg == currfg)
+ goto out;
+
remove_zspage(page, class, currfg);
insert_zspage(page, class, newfg);
- if (currfg != newfg)
- set_zspage_mapping(page, class_idx, newfg);
+ set_zspage_mapping(page, class_idx, newfg);
+out:
return newfg;
}
* to form a zspage for each size class. This is important
* to reduce wastage due to unusable space left at end of
* each zspage which is given as:
- * wastage = Zp - Zp % size_class
+ * wastage = Zp % class_size
+ * usage = Zp - wastage
* where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
*
* For example, for size class of 3/8 * PAGE_SIZE, we should
/*
* Encode <page, obj_idx> as a single handle value.
- * On hardware platforms with physical memory starting at 0x0 the pfn
- * could be 0 so we ensure that the handle will never be 0 by adjusting the
- * encoded obj_idx value before encoding.
+ * We use the least bit of handle for tagging.
*/
-static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
+static void *location_to_obj(struct page *page, unsigned long obj_idx)
{
- unsigned long handle;
+ unsigned long obj;
if (!page) {
BUG_ON(obj_idx);
return NULL;
}
- handle = page_to_pfn(page) << OBJ_INDEX_BITS;
- handle |= ((obj_idx + 1) & OBJ_INDEX_MASK);
+ obj = page_to_pfn(page) << OBJ_INDEX_BITS;
+ obj |= ((obj_idx) & OBJ_INDEX_MASK);
+ obj <<= OBJ_TAG_BITS;
- return (void *)handle;
+ return (void *)obj;
}
/*
* Decode <page, obj_idx> pair from the given object handle. We adjust the
* decoded obj_idx back to its original value since it was adjusted in
- * obj_location_to_handle().
+ * location_to_obj().
*/
-static void obj_handle_to_location(unsigned long handle, struct page **page,
+static void obj_to_location(unsigned long obj, struct page **page,
unsigned long *obj_idx)
{
- *page = pfn_to_page(handle >> OBJ_INDEX_BITS);
- *obj_idx = (handle & OBJ_INDEX_MASK) - 1;
+ obj >>= OBJ_TAG_BITS;
+ *page = pfn_to_page(obj >> OBJ_INDEX_BITS);
+ *obj_idx = (obj & OBJ_INDEX_MASK);
+}
+
+static unsigned long handle_to_obj(unsigned long handle)
+{
+ return *(unsigned long *)handle;
+}
+
+static unsigned long obj_to_head(struct size_class *class, struct page *page,
+ void *obj)
+{
+ if (class->huge) {
+ VM_BUG_ON(!is_first_page(page));
+ return *(unsigned long *)page_private(page);
+ } else
+ return *(unsigned long *)obj;
}
static unsigned long obj_idx_to_offset(struct page *page,
return off + obj_idx * class_size;
}
-static bool obj_handle_is_free(struct page *first_page,
- struct size_class *class, unsigned long handle)
+static inline int trypin_tag(unsigned long handle)
{
- unsigned long obj, idx, offset;
- struct page *page;
- struct link_free *link;
-
- BUG_ON(!is_first_page(first_page));
-
- obj = (unsigned long)first_page->freelist;
+ unsigned long *ptr = (unsigned long *)handle;
- while (obj) {
- if (obj == handle)
- return true;
-
- obj_handle_to_location(obj, &page, &idx);
- offset = obj_idx_to_offset(page, idx, class->size);
-
- link = (struct link_free *)kmap_atomic(page) +
- offset / sizeof(*link);
- obj = (unsigned long)link->next;
- kunmap_atomic(link);
- }
-
- return false;
+ return !test_and_set_bit_lock(HANDLE_PIN_BIT, ptr);
}
-static void obj_free(unsigned long obj, struct page *page, unsigned long offset)
+static void pin_tag(unsigned long handle)
{
- struct page *first_page = get_first_page(page);
- struct link_free *link;
+ while (!trypin_tag(handle));
+}
- /* Insert this object in containing zspage's freelist */
- link = (struct link_free *)((unsigned char *)kmap_atomic(page)
- + offset);
- link->next = first_page->freelist;
- kunmap_atomic(link);
- first_page->freelist = (void *)obj;
+static void unpin_tag(unsigned long handle)
+{
+ unsigned long *ptr = (unsigned long *)handle;
- first_page->inuse--;
+ clear_bit_unlock(HANDLE_PIN_BIT, ptr);
}
static void reset_page(struct page *page)
while (page) {
struct page *next_page;
struct link_free *link;
- unsigned int i, objs_on_page;
+ unsigned int i = 1;
+ void *vaddr;
/*
* page->index stores offset of first object starting
if (page != first_page)
page->index = off;
- link = (struct link_free *)kmap_atomic(page) +
- off / sizeof(*link);
- objs_on_page = (PAGE_SIZE - off) / class->size;
+ vaddr = kmap_atomic(page);
+ link = (struct link_free *)vaddr + off / sizeof(*link);
- for (i = 1; i <= objs_on_page; i++) {
- off += class->size;
- if (off < PAGE_SIZE) {
- link->next = obj_location_to_handle(page, i);
- link += class->size / sizeof(*link);
- }
+ while ((off += class->size) < PAGE_SIZE) {
+ link->next = location_to_obj(page, i++);
+ link += class->size / sizeof(*link);
}
/*
* page (if present)
*/
next_page = get_next_page(page);
- link->next = obj_location_to_handle(next_page, 0);
- kunmap_atomic(link);
+ link->next = location_to_obj(next_page, 0);
+ kunmap_atomic(vaddr);
page = next_page;
- off = (off + class->size) % PAGE_SIZE;
+ off %= PAGE_SIZE;
}
}
init_zspage(first_page, class);
- first_page->freelist = obj_location_to_handle(first_page, 0);
+ first_page->freelist = location_to_obj(first_page, 0);
/* Maximum number of objects we can store in this zspage */
first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
return first_page;
}
-/*
- * This tries to reclaim all the provided zspage's objects by calling the
- * zs_pool's ops->evict function for each object in use. This requires
- * the zspage's class lock to be held when calling this function. Since
- * the evict function may sleep, this drops the class lock before evicting
- * and objects. No other locks should be held when calling this function.
- * This will return with the class lock unlocked.
- *
- * If there is no zs_pool->ops or ops->evict function, this returns error.
- *
- * This returns 0 on success, -err on failure. On failure, some of the
- * objects may have been freed, but not all. On success, the entire zspage
- * has been freed and should not be used anymore.
- */
-static int reclaim_zspage(struct zs_pool *pool, struct page *first_page)
-{
- struct size_class *class;
- enum fullness_group fullness;
- struct page *page = first_page;
- unsigned long handle;
- int class_idx, ret = 0;
-
- BUG_ON(!is_first_page(first_page));
-
- get_zspage_mapping(first_page, &class_idx, &fullness);
- class = pool->size_class[class_idx];
-
- assert_spin_locked(&class->lock);
-
- if (!pool->ops || !pool->ops->evict) {
- spin_unlock(&class->lock);
- return -EINVAL;
- }
-
- /* move the zspage into the reclaim fullness group,
- * so it's not available for use by zs_malloc,
- * and won't be freed by zs_free
- */
- remove_zspage(first_page, class, fullness);
- set_zspage_mapping(first_page, class_idx, ZS_RECLAIM);
-
- spin_unlock(&class->lock);
-
- might_sleep();
-
- while (page) {
- unsigned long offset, idx = 0;
-
- while ((offset = obj_idx_to_offset(page, idx, class->size))
- < PAGE_SIZE) {
- handle = (unsigned long)obj_location_to_handle(page,
- idx++);
- if (obj_handle_is_free(first_page, class, handle))
- continue;
- ret = pool->ops->evict(pool, handle);
- if (ret) {
- spin_lock(&class->lock);
- fix_fullness_group(pool, first_page);
- spin_unlock(&class->lock);
- return ret;
- }
- obj_free(handle, page, offset);
- }
-
- page = get_next_page(page);
- }
-
- free_zspage(first_page);
-
- atomic_long_sub(class->pages_per_zspage, &pool->pages_allocated);
-
- return 0;
-}
-
-static struct page *find_available_zspage(struct size_class *class)
+static struct page *find_get_zspage(struct size_class *class)
{
int i;
struct page *page;
- for (i = 0; i < _ZS_NR_AVAILABLE_FULLNESS_GROUPS; i++) {
+ for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
page = class->fullness_list[i];
if (page)
break;
return page;
}
-/* this simply iterates atomically through all classes,
- * using a specific fullness group. At the end, it starts
- * over using the next fullness group, and so on. The
- * fullness groups are used in a specific order, from
- * least to most full.
- */
-static void find_next_lru_class_fg(struct zs_pool *pool,
- struct size_class **class, enum fullness_group *fg)
-{
- int i = atomic_inc_return(&lru_class_fg);
-
- if (i >= _ZS_NR_LRU_CLASS_FG) {
- int orig = i;
-
- i %= _ZS_NR_LRU_CLASS_FG;
- /* only need to try once, since if we don't
- * succeed whoever changed it will also try
- * and eventually someone will reset it
- */
- atomic_cmpxchg(&lru_class_fg, orig, i);
- }
- *class = pool->size_class[i % ZS_SIZE_CLASSES];
- *fg = lru_fg[i / ZS_SIZE_CLASSES];
-}
-
-/*
- * This attempts to find the LRU zspage, but that's not really possible
- * because zspages are not contained in a single LRU list, they're
- * contained inside fullness groups which are themselves contained
- * inside classes. So this simply iterates through the classes and
- * fullness groups to find the next non-empty fullness group, and
- * uses the LRU zspage there.
- *
- * On success, the zspage is returned with its class locked.
- * On failure, NULL is returned.
- */
-static struct page *find_lru_zspage(struct zs_pool *pool)
-{
- struct size_class *class;
- struct page *page;
- enum fullness_group fg;
- int tries = 0;
-
- while (tries++ < _ZS_NR_LRU_CLASS_FG) {
- find_next_lru_class_fg(pool, &class, &fg);
-
- spin_lock(&class->lock);
-
- page = class->fullness_list[fg];
- if (page)
- return list_prev_entry(page, lru);
-
- spin_unlock(&class->lock);
- }
-
- return NULL;
-}
-
#ifdef CONFIG_PGTABLE_MAPPING
static inline int __zs_cpu_up(struct mapping_area *area)
{
static inline void *__zs_map_object(struct mapping_area *area,
struct page *pages[2], int off, int size)
{
- BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, pages));
+ BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, &pages));
area->vm_addr = area->vm->addr;
return area->vm_addr + off;
}
*/
if (area->vm_buf)
return 0;
- area->vm_buf = (char *)__get_free_page(GFP_KERNEL);
+ area->vm_buf = kmalloc(ZS_MAX_ALLOC_SIZE, GFP_KERNEL);
if (!area->vm_buf)
return -ENOMEM;
return 0;
static inline void __zs_cpu_down(struct mapping_area *area)
{
- if (area->vm_buf)
- free_page((unsigned long)area->vm_buf);
+ kfree(area->vm_buf);
area->vm_buf = NULL;
}
{
int sizes[2];
void *addr;
- char *buf = area->vm_buf;
+ char *buf;
/* no write fastpath */
if (area->vm_mm == ZS_MM_RO)
goto out;
+ buf = area->vm_buf;
+ if (!area->huge) {
+ buf = buf + ZS_HANDLE_SIZE;
+ size -= ZS_HANDLE_SIZE;
+ off += ZS_HANDLE_SIZE;
+ }
+
sizes[0] = PAGE_SIZE - off;
sizes[1] = size - sizes[0];
.notifier_call = zs_cpu_notifier
};
-static void zs_exit(void)
+static int zs_register_cpu_notifier(void)
{
- int cpu;
-
-#ifdef CONFIG_ZPOOL
- zpool_unregister_driver(&zs_zpool_driver);
-#endif
+ int cpu, uninitialized_var(ret);
cpu_notifier_register_begin();
- for_each_online_cpu(cpu)
- zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
- __unregister_cpu_notifier(&zs_cpu_nb);
+ __register_cpu_notifier(&zs_cpu_nb);
+ for_each_online_cpu(cpu) {
+ ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
+ if (notifier_to_errno(ret))
+ break;
+ }
cpu_notifier_register_done();
+ return notifier_to_errno(ret);
}
-static int zs_init(void)
+static void zs_unregister_cpu_notifier(void)
{
- int cpu, ret;
+ int cpu;
cpu_notifier_register_begin();
- __register_cpu_notifier(&zs_cpu_nb);
- for_each_online_cpu(cpu) {
- ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
- if (notifier_to_errno(ret)) {
- cpu_notifier_register_done();
- goto fail;
- }
- }
+ for_each_online_cpu(cpu)
+ zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
+ __unregister_cpu_notifier(&zs_cpu_nb);
cpu_notifier_register_done();
-
-#ifdef CONFIG_ZPOOL
- zpool_register_driver(&zs_zpool_driver);
-#endif
-
- return 0;
-fail:
- zs_exit();
- return notifier_to_errno(ret);
}
-static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
+static void init_zs_size_classes(void)
{
- return pages_per_zspage * PAGE_SIZE / size;
+ int nr;
+
+ nr = (ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / ZS_SIZE_CLASS_DELTA + 1;
+ if ((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) % ZS_SIZE_CLASS_DELTA)
+ nr += 1;
+
+ zs_size_classes = nr;
}
static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
return true;
}
+static bool zspage_full(struct page *page)
+{
+ BUG_ON(!is_first_page(page));
+
+ return page->inuse == page->objects;
+}
+
+unsigned long zs_get_total_pages(struct zs_pool *pool)
+{
+ return atomic_long_read(&pool->pages_allocated);
+}
+EXPORT_SYMBOL_GPL(zs_get_total_pages);
+
/**
- * zs_create_pool - Creates an allocation pool to work from.
- * @flags: allocation flags used to allocate pool metadata
+ * zs_map_object - get address of allocated object from handle.
+ * @pool: pool from which the object was allocated
+ * @handle: handle returned from zs_malloc
*
- * This function must be called before anything when using
- * the zsmalloc allocator.
+ * Before using an object allocated from zs_malloc, it must be mapped using
+ * this function. When done with the object, it must be unmapped using
+ * zs_unmap_object.
*
- * On success, a pointer to the newly created pool is returned,
- * otherwise NULL.
+ * Only one object can be mapped per cpu at a time. There is no protection
+ * against nested mappings.
+ *
+ * This function returns with preemption and page faults disabled.
*/
-struct zs_pool *zs_create_pool(gfp_t flags, struct zs_ops *ops)
+void *zs_map_object(struct zs_pool *pool, unsigned long handle,
+ enum zs_mapmode mm)
{
- int i, ovhd_size;
- struct zs_pool *pool;
+ struct page *page;
+ unsigned long obj, obj_idx, off;
- ovhd_size = roundup(sizeof(*pool), PAGE_SIZE);
- pool = kzalloc(ovhd_size, GFP_KERNEL);
- if (!pool)
- return NULL;
+ unsigned int class_idx;
+ enum fullness_group fg;
+ struct size_class *class;
+ struct mapping_area *area;
+ struct page *pages[2];
+ void *ret;
+
+ BUG_ON(!handle);
/*
- * Iterate reversly, because, size of size_class that we want to use
- * for merging should be larger or equal to current size.
+ * Because we use per-cpu mapping areas shared among the
+ * pools/users, we can't allow mapping in interrupt context
+ * because it can corrupt another users mappings.
*/
- for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
- int size;
- int pages_per_zspage;
- struct size_class *class;
- struct size_class *prev_class;
-
- size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
- if (size > ZS_MAX_ALLOC_SIZE)
- size = ZS_MAX_ALLOC_SIZE;
- pages_per_zspage = get_pages_per_zspage(size);
+ BUG_ON(in_interrupt());
- /*
- * size_class is used for normal zsmalloc operation such
- * as alloc/free for that size. Although it is natural that we
- * have one size_class for each size, there is a chance that we
- * can get more memory utilization if we use one size_class for
- * many different sizes whose size_class have same
- * characteristics. So, we makes size_class point to
- * previous size_class if possible.
- */
- if (i < ZS_SIZE_CLASSES - 1) {
- prev_class = pool->size_class[i + 1];
- if (can_merge(prev_class, size, pages_per_zspage)) {
- pool->size_class[i] = prev_class;
- continue;
- }
- }
+ /* From now on, migration cannot move the object */
+ pin_tag(handle);
- class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
- if (!class)
- goto err;
+ obj = handle_to_obj(handle);
+ obj_to_location(obj, &page, &obj_idx);
+ get_zspage_mapping(get_first_page(page), &class_idx, &fg);
+ class = pool->size_class[class_idx];
+ off = obj_idx_to_offset(page, obj_idx, class->size);
- class->size = size;
- class->index = i;
- class->pages_per_zspage = pages_per_zspage;
- spin_lock_init(&class->lock);
- pool->size_class[i] = class;
+ area = &get_cpu_var(zs_map_area);
+ area->vm_mm = mm;
+ if (off + class->size <= PAGE_SIZE) {
+ /* this object is contained entirely within a page */
+ area->vm_addr = kmap_atomic(page);
+ ret = area->vm_addr + off;
+ goto out;
}
- pool->flags = flags;
- pool->ops = ops;
+ /* this object spans two pages */
+ pages[0] = page;
+ pages[1] = get_next_page(page);
+ BUG_ON(!pages[1]);
- return pool;
+ ret = __zs_map_object(area, pages, off, class->size);
+out:
+ if (!class->huge)
+ ret += ZS_HANDLE_SIZE;
-err:
- zs_destroy_pool(pool);
- return NULL;
+ return ret;
}
-EXPORT_SYMBOL_GPL(zs_create_pool);
+EXPORT_SYMBOL_GPL(zs_map_object);
-void zs_destroy_pool(struct zs_pool *pool)
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
{
- int i;
+ struct page *page;
+ unsigned long obj, obj_idx, off;
- for (i = 0; i < ZS_SIZE_CLASSES; i++) {
- int fg;
- struct size_class *class = pool->size_class[i];
+ unsigned int class_idx;
+ enum fullness_group fg;
+ struct size_class *class;
+ struct mapping_area *area;
- if (!class)
- continue;
+ BUG_ON(!handle);
- if (class->index != i)
- continue;
+ obj = handle_to_obj(handle);
+ obj_to_location(obj, &page, &obj_idx);
+ get_zspage_mapping(get_first_page(page), &class_idx, &fg);
+ class = pool->size_class[class_idx];
+ off = obj_idx_to_offset(page, obj_idx, class->size);
- for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
- if (class->fullness_list[fg]) {
- pr_info("Freeing non-empty class with size %db, fullness group %d\n",
- class->size, fg);
- }
- }
- kfree(class);
+ area = this_cpu_ptr(&zs_map_area);
+ if (off + class->size <= PAGE_SIZE)
+ kunmap_atomic(area->vm_addr);
+ else {
+ struct page *pages[2];
+
+ pages[0] = page;
+ pages[1] = get_next_page(page);
+ BUG_ON(!pages[1]);
+
+ __zs_unmap_object(area, pages, off, class->size);
}
- kfree(pool);
+ put_cpu_var(zs_map_area);
+ unpin_tag(handle);
}
-EXPORT_SYMBOL_GPL(zs_destroy_pool);
+EXPORT_SYMBOL_GPL(zs_unmap_object);
+
+static unsigned long obj_malloc(struct page *first_page,
+ struct size_class *class, unsigned long handle)
+{
+ unsigned long obj;
+ struct link_free *link;
+
+ struct page *m_page;
+ unsigned long m_objidx, m_offset;
+ void *vaddr;
+
+ handle |= OBJ_ALLOCATED_TAG;
+ obj = (unsigned long)first_page->freelist;
+ obj_to_location(obj, &m_page, &m_objidx);
+ m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
+
+ vaddr = kmap_atomic(m_page);
+ link = (struct link_free *)vaddr + m_offset / sizeof(*link);
+ first_page->freelist = link->next;
+ if (!class->huge)
+ /* record handle in the header of allocated chunk */
+ link->handle = handle;
+ else
+ /* record handle in first_page->private */
+ set_page_private(first_page, handle);
+ kunmap_atomic(vaddr);
+ first_page->inuse++;
+ zs_stat_inc(class, OBJ_USED, 1);
+
+ return obj;
+}
+
/**
* zs_malloc - Allocate block of given size from pool.
*/
unsigned long zs_malloc(struct zs_pool *pool, size_t size)
{
- unsigned long obj;
- struct link_free *link;
+ unsigned long handle, obj;
struct size_class *class;
-
- struct page *first_page, *m_page;
- unsigned long m_objidx, m_offset;
+ struct page *first_page;
if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
return 0;
+ handle = alloc_handle(pool);
+ if (!handle)
+ return 0;
+
+ /* extra space in chunk to keep the handle */
+ size += ZS_HANDLE_SIZE;
class = pool->size_class[get_size_class_index(size)];
spin_lock(&class->lock);
- first_page = find_available_zspage(class);
+ first_page = find_get_zspage(class);
if (!first_page) {
spin_unlock(&class->lock);
first_page = alloc_zspage(class, pool->flags);
- if (unlikely(!first_page))
+ if (unlikely(!first_page)) {
+ free_handle(pool, handle);
return 0;
+ }
set_zspage_mapping(first_page, class->index, ZS_EMPTY);
atomic_long_add(class->pages_per_zspage,
&pool->pages_allocated);
+
spin_lock(&class->lock);
+ zs_stat_inc(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+ class->size, class->pages_per_zspage));
}
- obj = (unsigned long)first_page->freelist;
- obj_handle_to_location(obj, &m_page, &m_objidx);
- m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
-
- link = (struct link_free *)kmap_atomic(m_page) +
- m_offset / sizeof(*link);
- first_page->freelist = link->next;
- memset(link, POISON_INUSE, sizeof(*link));
- kunmap_atomic(link);
-
- first_page->inuse++;
+ obj = obj_malloc(first_page, class, handle);
/* Now move the zspage to another fullness group, if required */
- fix_fullness_group(pool, first_page);
+ fix_fullness_group(class, first_page);
+ record_obj(handle, obj);
spin_unlock(&class->lock);
- return obj;
+ return handle;
}
EXPORT_SYMBOL_GPL(zs_malloc);
-/**
- * zs_free - Free the handle from this pool.
- * @pool: pool containing the handle
- * @obj: the handle to free
- *
- * The caller must provide a valid handle that is contained
- * in the provided pool. The caller must ensure this is
- * not called after evict() has returned successfully for the
- * handle.
- */
-void zs_free(struct zs_pool *pool, unsigned long obj)
+static void obj_free(struct zs_pool *pool, struct size_class *class,
+ unsigned long obj)
{
+ struct link_free *link;
struct page *first_page, *f_page;
unsigned long f_objidx, f_offset;
+ void *vaddr;
+ int class_idx;
+ enum fullness_group fullness;
+
+ BUG_ON(!obj);
+
+ obj &= ~OBJ_ALLOCATED_TAG;
+ obj_to_location(obj, &f_page, &f_objidx);
+ first_page = get_first_page(f_page);
+
+ get_zspage_mapping(first_page, &class_idx, &fullness);
+ f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
+
+ vaddr = kmap_atomic(f_page);
+
+ /* Insert this object in containing zspage's freelist */
+ link = (struct link_free *)(vaddr + f_offset);
+ link->next = first_page->freelist;
+ if (class->huge)
+ set_page_private(first_page, 0);
+ kunmap_atomic(vaddr);
+ first_page->freelist = (void *)obj;
+ first_page->inuse--;
+ zs_stat_dec(class, OBJ_USED, 1);
+}
+void zs_free(struct zs_pool *pool, unsigned long handle)
+{
+ struct page *first_page, *f_page;
+ unsigned long obj, f_objidx;
int class_idx;
struct size_class *class;
enum fullness_group fullness;
- if (unlikely(!obj))
+ if (unlikely(!handle))
return;
- obj_handle_to_location(obj, &f_page, &f_objidx);
+ pin_tag(handle);
+ obj = handle_to_obj(handle);
+ obj_to_location(obj, &f_page, &f_objidx);
first_page = get_first_page(f_page);
get_zspage_mapping(first_page, &class_idx, &fullness);
class = pool->size_class[class_idx];
- f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
spin_lock(&class->lock);
+ obj_free(pool, class, obj);
+ fullness = fix_fullness_group(class, first_page);
+ if (fullness == ZS_EMPTY) {
+ zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+ class->size, class->pages_per_zspage));
+ atomic_long_sub(class->pages_per_zspage,
+ &pool->pages_allocated);
+ free_zspage(first_page);
+ }
+ spin_unlock(&class->lock);
+ unpin_tag(handle);
- /* must re-check fullness after taking class lock */
- get_zspage_mapping(first_page, &class_idx, &fullness);
- if (fullness == ZS_RECLAIM) {
- spin_unlock(&class->lock);
- return; /* will be freed during reclaim */
+ free_handle(pool, handle);
+}
+EXPORT_SYMBOL_GPL(zs_free);
+
+static void zs_object_copy(unsigned long src, unsigned long dst,
+ struct size_class *class)
+{
+ struct page *s_page, *d_page;
+ unsigned long s_objidx, d_objidx;
+ unsigned long s_off, d_off;
+ void *s_addr, *d_addr;
+ int s_size, d_size, size;
+ int written = 0;
+
+ s_size = d_size = class->size;
+
+ obj_to_location(src, &s_page, &s_objidx);
+ obj_to_location(dst, &d_page, &d_objidx);
+
+ s_off = obj_idx_to_offset(s_page, s_objidx, class->size);
+ d_off = obj_idx_to_offset(d_page, d_objidx, class->size);
+
+ if (s_off + class->size > PAGE_SIZE)
+ s_size = PAGE_SIZE - s_off;
+
+ if (d_off + class->size > PAGE_SIZE)
+ d_size = PAGE_SIZE - d_off;
+
+ s_addr = kmap_atomic(s_page);
+ d_addr = kmap_atomic(d_page);
+
+ while (1) {
+ size = min(s_size, d_size);
+ memcpy(d_addr + d_off, s_addr + s_off, size);
+ written += size;
+
+ if (written == class->size)
+ break;
+
+ s_off += size;
+ s_size -= size;
+ d_off += size;
+ d_size -= size;
+
+ if (s_off >= PAGE_SIZE) {
+ kunmap_atomic(d_addr);
+ kunmap_atomic(s_addr);
+ s_page = get_next_page(s_page);
+ BUG_ON(!s_page);
+ s_addr = kmap_atomic(s_page);
+ d_addr = kmap_atomic(d_page);
+ s_size = class->size - written;
+ s_off = 0;
+ }
+
+ if (d_off >= PAGE_SIZE) {
+ kunmap_atomic(d_addr);
+ d_page = get_next_page(d_page);
+ BUG_ON(!d_page);
+ d_addr = kmap_atomic(d_page);
+ d_size = class->size - written;
+ d_off = 0;
+ }
}
- obj_free(obj, f_page, f_offset);
+ kunmap_atomic(d_addr);
+ kunmap_atomic(s_addr);
+}
- fullness = fix_fullness_group(pool, first_page);
- spin_unlock(&class->lock);
+/*
+ * Find alloced object in zspage from index object and
+ * return handle.
+ */
+static unsigned long find_alloced_obj(struct page *page, int index,
+ struct size_class *class)
+{
+ unsigned long head;
+ int offset = 0;
+ unsigned long handle = 0;
+ void *addr = kmap_atomic(page);
+
+ if (!is_first_page(page))
+ offset = page->index;
+ offset += class->size * index;
+
+ while (offset < PAGE_SIZE) {
+ head = obj_to_head(class, page, addr + offset);
+ if (head & OBJ_ALLOCATED_TAG) {
+ handle = head & ~OBJ_ALLOCATED_TAG;
+ if (trypin_tag(handle))
+ break;
+ handle = 0;
+ }
+
+ offset += class->size;
+ index++;
+ }
+
+ kunmap_atomic(addr);
+ return handle;
+}
+
+struct zs_compact_control {
+ /* Source page for migration which could be a subpage of zspage. */
+ struct page *s_page;
+ /* Destination page for migration which should be a first page
+ * of zspage. */
+ struct page *d_page;
+ /* Starting object index within @s_page which used for live object
+ * in the subpage. */
+ int index;
+ /* how many of objects are migrated */
+ int nr_migrated;
+};
+
+static int migrate_zspage(struct zs_pool *pool, struct size_class *class,
+ struct zs_compact_control *cc)
+{
+ unsigned long used_obj, free_obj;
+ unsigned long handle;
+ struct page *s_page = cc->s_page;
+ struct page *d_page = cc->d_page;
+ unsigned long index = cc->index;
+ int nr_migrated = 0;
+ int ret = 0;
+
+ while (1) {
+ handle = find_alloced_obj(s_page, index, class);
+ if (!handle) {
+ s_page = get_next_page(s_page);
+ if (!s_page)
+ break;
+ index = 0;
+ continue;
+ }
+
+ /* Stop if there is no more space */
+ if (zspage_full(d_page)) {
+ unpin_tag(handle);
+ ret = -ENOMEM;
+ break;
+ }
+
+ used_obj = handle_to_obj(handle);
+ free_obj = obj_malloc(d_page, class, handle);
+ zs_object_copy(used_obj, free_obj, class);
+ index++;
+ /*
+ * record_obj updates handle's value to free_obj and it will
+ * invalidate lock bit(ie, HANDLE_PIN_BIT) of handle, which
+ * breaks synchronization using pin_tag(e,g, zs_free) so
+ * let's keep the lock bit.
+ */
+ free_obj |= BIT(HANDLE_PIN_BIT);
+ record_obj(handle, free_obj);
+ unpin_tag(handle);
+ obj_free(pool, class, used_obj);
+ nr_migrated++;
+ }
+
+ /* Remember last position in this iteration */
+ cc->s_page = s_page;
+ cc->index = index;
+ cc->nr_migrated = nr_migrated;
+
+ return ret;
+}
+
+static struct page *alloc_target_page(struct size_class *class)
+{
+ int i;
+ struct page *page;
+
+ for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
+ page = class->fullness_list[i];
+ if (page) {
+ remove_zspage(page, class, i);
+ break;
+ }
+ }
+
+ return page;
+}
+
+static void putback_zspage(struct zs_pool *pool, struct size_class *class,
+ struct page *first_page)
+{
+ enum fullness_group fullness;
+
+ BUG_ON(!is_first_page(first_page));
+
+ fullness = get_fullness_group(first_page);
+ insert_zspage(first_page, class, fullness);
+ set_zspage_mapping(first_page, class->index, fullness);
if (fullness == ZS_EMPTY) {
+ zs_stat_dec(class, OBJ_ALLOCATED, get_maxobj_per_zspage(
+ class->size, class->pages_per_zspage));
atomic_long_sub(class->pages_per_zspage,
&pool->pages_allocated);
+
free_zspage(first_page);
}
}
-EXPORT_SYMBOL_GPL(zs_free);
-/**
- * zs_shrink - Shrink the pool
- * @pool: pool to shrink
- *
- * The pool will be shrunk by one zspage, which is some
- * number of pages in size. On success, the number of freed
- * pages is returned. On failure, the error is returned.
- */
-int zs_shrink(struct zs_pool *pool)
+static struct page *isolate_source_page(struct size_class *class)
{
- struct size_class *class;
- enum fullness_group fullness;
struct page *page;
- int class_idx, ret;
- if (!pool->ops || !pool->ops->evict)
- return -EINVAL;
+ page = class->fullness_list[ZS_ALMOST_EMPTY];
+ if (page)
+ remove_zspage(page, class, ZS_ALMOST_EMPTY);
- /* if a page is found, the class is locked */
- page = find_lru_zspage(pool);
- if (!page)
- return -ENOENT;
+ return page;
+}
- get_zspage_mapping(page, &class_idx, &fullness);
- class = pool->size_class[class_idx];
+static unsigned long __zs_compact(struct zs_pool *pool,
+ struct size_class *class)
+{
+ int nr_to_migrate;
+ struct zs_compact_control cc;
+ struct page *src_page;
+ struct page *dst_page = NULL;
+ unsigned long nr_total_migrated = 0;
- /* reclaim_zspage unlocks the class lock */
- ret = reclaim_zspage(pool, page);
- if (ret)
- return ret;
+ spin_lock(&class->lock);
+ while ((src_page = isolate_source_page(class))) {
+
+ BUG_ON(!is_first_page(src_page));
+
+ /* The goal is to migrate all live objects in source page */
+ nr_to_migrate = src_page->inuse;
+ cc.index = 0;
+ cc.s_page = src_page;
+
+ while ((dst_page = alloc_target_page(class))) {
+ cc.d_page = dst_page;
+ /*
+ * If there is no more space in dst_page, try to
+ * allocate another zspage.
+ */
+ if (!migrate_zspage(pool, class, &cc))
+ break;
+
+ putback_zspage(pool, class, dst_page);
+ nr_total_migrated += cc.nr_migrated;
+ nr_to_migrate -= cc.nr_migrated;
+ }
+
+ /* Stop if we couldn't find slot */
+ if (dst_page == NULL)
+ break;
+
+ putback_zspage(pool, class, dst_page);
+ putback_zspage(pool, class, src_page);
+ spin_unlock(&class->lock);
+ nr_total_migrated += cc.nr_migrated;
+ cond_resched();
+ spin_lock(&class->lock);
+ }
+
+ if (src_page)
+ putback_zspage(pool, class, src_page);
+
+ spin_unlock(&class->lock);
+
+ return nr_total_migrated;
+}
+
+unsigned long zs_compact(struct zs_pool *pool)
+{
+ int i;
+ unsigned long nr_migrated = 0;
+ struct size_class *class;
- return class->pages_per_zspage;
+ for (i = zs_size_classes - 1; i >= 0; i--) {
+ class = pool->size_class[i];
+ if (!class)
+ continue;
+ if (class->index != i)
+ continue;
+ nr_migrated += __zs_compact(pool, class);
+ }
+
+ return nr_migrated;
}
-EXPORT_SYMBOL_GPL(zs_shrink);
+EXPORT_SYMBOL_GPL(zs_compact);
/**
- * zs_map_object - get address of allocated object from handle.
- * @pool: pool from which the object was allocated
- * @handle: handle returned from zs_malloc
- *
- * Before using an object allocated from zs_malloc, it must be mapped using
- * this function. When done with the object, it must be unmapped using
- * zs_unmap_object.
+ * zs_create_pool - Creates an allocation pool to work from.
+ * @flags: allocation flags used to allocate pool metadata
*
- * Only one object can be mapped per cpu at a time. There is no protection
- * against nested mappings.
+ * This function must be called before anything when using
+ * the zsmalloc allocator.
*
- * This function returns with preemption and page faults disabled.
+ * On success, a pointer to the newly created pool is returned,
+ * otherwise NULL.
*/
-void *zs_map_object(struct zs_pool *pool, unsigned long handle,
- enum zs_mapmode mm)
+struct zs_pool *zs_create_pool(char *name, gfp_t flags)
{
- struct page *page;
- unsigned long obj_idx, off;
+ int i;
+ struct zs_pool *pool;
+ struct size_class *prev_class = NULL;
- unsigned int class_idx;
- enum fullness_group fg;
- struct size_class *class;
- struct mapping_area *area;
- struct page *pages[2];
+ pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+ if (!pool)
+ return NULL;
- BUG_ON(!handle);
+ pool->size_class = kcalloc(zs_size_classes, sizeof(struct size_class *),
+ GFP_KERNEL);
+ if (!pool->size_class) {
+ kfree(pool);
+ return NULL;
+ }
+
+ pool->name = kstrdup(name, GFP_KERNEL);
+ if (!pool->name)
+ goto err;
+
+ if (create_handle_cache(pool))
+ goto err;
/*
- * Because we use per-cpu mapping areas shared among the
- * pools/users, we can't allow mapping in interrupt context
- * because it can corrupt another users mappings.
+ * Iterate reversly, because, size of size_class that we want to use
+ * for merging should be larger or equal to current size.
*/
- BUG_ON(in_interrupt());
+ for (i = zs_size_classes - 1; i >= 0; i--) {
+ int size;
+ int pages_per_zspage;
+ struct size_class *class;
- obj_handle_to_location(handle, &page, &obj_idx);
- get_zspage_mapping(get_first_page(page), &class_idx, &fg);
- class = pool->size_class[class_idx];
- off = obj_idx_to_offset(page, obj_idx, class->size);
+ size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
+ if (size > ZS_MAX_ALLOC_SIZE)
+ size = ZS_MAX_ALLOC_SIZE;
+ pages_per_zspage = get_pages_per_zspage(size);
- area = &get_cpu_var(zs_map_area);
- area->vm_mm = mm;
- if (off + class->size <= PAGE_SIZE) {
- /* this object is contained entirely within a page */
- area->vm_addr = kmap_atomic(page);
- return area->vm_addr + off;
+ /*
+ * size_class is used for normal zsmalloc operation such
+ * as alloc/free for that size. Although it is natural that we
+ * have one size_class for each size, there is a chance that we
+ * can get more memory utilization if we use one size_class for
+ * many different sizes whose size_class have same
+ * characteristics. So, we makes size_class point to
+ * previous size_class if possible.
+ */
+ if (prev_class) {
+ if (can_merge(prev_class, size, pages_per_zspage)) {
+ pool->size_class[i] = prev_class;
+ continue;
+ }
+ }
+
+ class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
+ if (!class)
+ goto err;
+
+ class->size = size;
+ class->index = i;
+ class->pages_per_zspage = pages_per_zspage;
+ if (pages_per_zspage == 1 &&
+ get_maxobj_per_zspage(size, pages_per_zspage) == 1)
+ class->huge = true;
+ spin_lock_init(&class->lock);
+ pool->size_class[i] = class;
+
+ prev_class = class;
}
- /* this object spans two pages */
- pages[0] = page;
- pages[1] = get_next_page(page);
- BUG_ON(!pages[1]);
+ pool->flags = flags;
+
+ if (zs_pool_stat_create(name, pool))
+ goto err;
- return __zs_map_object(area, pages, off, class->size);
+ return pool;
+
+err:
+ zs_destroy_pool(pool);
+ return NULL;
}
-EXPORT_SYMBOL_GPL(zs_map_object);
+EXPORT_SYMBOL_GPL(zs_create_pool);
-void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
+void zs_destroy_pool(struct zs_pool *pool)
{
- struct page *page;
- unsigned long obj_idx, off;
+ int i;
- unsigned int class_idx;
- enum fullness_group fg;
- struct size_class *class;
- struct mapping_area *area;
+ zs_pool_stat_destroy(pool);
- BUG_ON(!handle);
+ for (i = 0; i < zs_size_classes; i++) {
+ int fg;
+ struct size_class *class = pool->size_class[i];
- obj_handle_to_location(handle, &page, &obj_idx);
- get_zspage_mapping(get_first_page(page), &class_idx, &fg);
- class = pool->size_class[class_idx];
- off = obj_idx_to_offset(page, obj_idx, class->size);
+ if (!class)
+ continue;
- area = this_cpu_ptr(&zs_map_area);
- if (off + class->size <= PAGE_SIZE)
- kunmap_atomic(area->vm_addr);
- else {
- struct page *pages[2];
+ if (class->index != i)
+ continue;
- pages[0] = page;
- pages[1] = get_next_page(page);
- BUG_ON(!pages[1]);
+ for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
+ if (class->fullness_list[fg]) {
+ pr_info("Freeing non-empty class with size %db, fullness group %d\n",
+ class->size, fg);
+ }
+ }
+ kfree(class);
+ }
- __zs_unmap_object(area, pages, off, class->size);
+ destroy_handle_cache(pool);
+ kfree(pool->size_class);
+ kfree(pool->name);
+ kfree(pool);
+}
+EXPORT_SYMBOL_GPL(zs_destroy_pool);
+
+static int __init zs_init(void)
+{
+ int ret = zs_register_cpu_notifier();
+
+ if (ret)
+ goto notifier_fail;
+
+ init_zs_size_classes();
+
+#ifdef CONFIG_ZPOOL
+ zpool_register_driver(&zs_zpool_driver);
+#endif
+
+ ret = zs_stat_init();
+ if (ret) {
+ pr_err("zs stat initialization failed\n");
+ goto stat_fail;
}
- put_cpu_var(zs_map_area);
+ return 0;
+
+stat_fail:
+#ifdef CONFIG_ZPOOL
+ zpool_unregister_driver(&zs_zpool_driver);
+#endif
+notifier_fail:
+ zs_unregister_cpu_notifier();
+
+ return ret;
}
-EXPORT_SYMBOL_GPL(zs_unmap_object);
-unsigned long zs_get_total_pages(struct zs_pool *pool)
+static void __exit zs_exit(void)
{
- return atomic_long_read(&pool->pages_allocated);
+#ifdef CONFIG_ZPOOL
+ zpool_unregister_driver(&zs_zpool_driver);
+#endif
+ zs_unregister_cpu_notifier();
+
+ zs_stat_exit();
}
-EXPORT_SYMBOL_GPL(zs_get_total_pages);
module_init(zs_init);
module_exit(zs_exit);
projects / GitHub / LineageOS / android_kernel_samsung_universal7580.git / commitdiff