4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
14 #include <linux/slab.h>
15 #include <linux/sched/autogroup.h>
16 #include <linux/sched/mm.h>
17 #include <linux/sched/coredump.h>
18 #include <linux/sched/user.h>
19 #include <linux/sched/numa_balancing.h>
20 #include <linux/sched/stat.h>
21 #include <linux/sched/task.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/sched/cputime.h>
24 #include <linux/rtmutex.h>
25 #include <linux/init.h>
26 #include <linux/unistd.h>
27 #include <linux/module.h>
28 #include <linux/vmalloc.h>
29 #include <linux/completion.h>
30 #include <linux/personality.h>
31 #include <linux/mempolicy.h>
32 #include <linux/sem.h>
33 #include <linux/file.h>
34 #include <linux/fdtable.h>
35 #include <linux/iocontext.h>
36 #include <linux/key.h>
37 #include <linux/binfmts.h>
38 #include <linux/mman.h>
39 #include <linux/mmu_notifier.h>
42 #include <linux/vmacache.h>
43 #include <linux/nsproxy.h>
44 #include <linux/capability.h>
45 #include <linux/cpu.h>
46 #include <linux/cgroup.h>
47 #include <linux/security.h>
48 #include <linux/hugetlb.h>
49 #include <linux/seccomp.h>
50 #include <linux/swap.h>
51 #include <linux/syscalls.h>
52 #include <linux/jiffies.h>
53 #include <linux/futex.h>
54 #include <linux/compat.h>
55 #include <linux/kthread.h>
56 #include <linux/task_io_accounting_ops.h>
57 #include <linux/rcupdate.h>
58 #include <linux/ptrace.h>
59 #include <linux/mount.h>
60 #include <linux/audit.h>
61 #include <linux/memcontrol.h>
62 #include <linux/ftrace.h>
63 #include <linux/proc_fs.h>
64 #include <linux/profile.h>
65 #include <linux/rmap.h>
66 #include <linux/ksm.h>
67 #include <linux/acct.h>
68 #include <linux/userfaultfd_k.h>
69 #include <linux/tsacct_kern.h>
70 #include <linux/cn_proc.h>
71 #include <linux/freezer.h>
72 #include <linux/delayacct.h>
73 #include <linux/taskstats_kern.h>
74 #include <linux/random.h>
75 #include <linux/tty.h>
76 #include <linux/blkdev.h>
77 #include <linux/fs_struct.h>
78 #include <linux/magic.h>
79 #include <linux/perf_event.h>
80 #include <linux/posix-timers.h>
81 #include <linux/user-return-notifier.h>
82 #include <linux/oom.h>
83 #include <linux/khugepaged.h>
84 #include <linux/signalfd.h>
85 #include <linux/uprobes.h>
86 #include <linux/aio.h>
87 #include <linux/compiler.h>
88 #include <linux/sysctl.h>
89 #include <linux/kcov.h>
90 #include <linux/livepatch.h>
92 #include <asm/pgtable.h>
93 #include <asm/pgalloc.h>
94 #include <linux/uaccess.h>
95 #include <asm/mmu_context.h>
96 #include <asm/cacheflush.h>
97 #include <asm/tlbflush.h>
99 #include <trace/events/sched.h>
101 #define CREATE_TRACE_POINTS
102 #include <trace/events/task.h>
105 * Minimum number of threads to boot the kernel
107 #define MIN_THREADS 20
110 * Maximum number of threads
112 #define MAX_THREADS FUTEX_TID_MASK
115 * Protected counters by write_lock_irq(&tasklist_lock)
117 unsigned long total_forks
; /* Handle normal Linux uptimes. */
118 int nr_threads
; /* The idle threads do not count.. */
120 int max_threads
; /* tunable limit on nr_threads */
122 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
124 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
126 #ifdef CONFIG_PROVE_RCU
127 int lockdep_tasklist_lock_is_held(void)
129 return lockdep_is_held(&tasklist_lock
);
131 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
132 #endif /* #ifdef CONFIG_PROVE_RCU */
134 int nr_processes(void)
139 for_each_possible_cpu(cpu
)
140 total
+= per_cpu(process_counts
, cpu
);
145 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
149 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
150 static struct kmem_cache
*task_struct_cachep
;
152 static inline struct task_struct
*alloc_task_struct_node(int node
)
154 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
157 static inline void free_task_struct(struct task_struct
*tsk
)
159 kmem_cache_free(task_struct_cachep
, tsk
);
163 void __weak
arch_release_thread_stack(unsigned long *stack
)
167 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
170 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
171 * kmemcache based allocator.
173 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
175 #ifdef CONFIG_VMAP_STACK
177 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
178 * flush. Try to minimize the number of calls by caching stacks.
180 #define NR_CACHED_STACKS 2
181 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
184 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
186 #ifdef CONFIG_VMAP_STACK
191 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
192 struct vm_struct
*s
= this_cpu_read(cached_stacks
[i
]);
196 this_cpu_write(cached_stacks
[i
], NULL
);
198 tsk
->stack_vm_area
= s
;
204 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_SIZE
,
205 VMALLOC_START
, VMALLOC_END
,
206 THREADINFO_GFP
| __GFP_HIGHMEM
,
208 0, node
, __builtin_return_address(0));
211 * We can't call find_vm_area() in interrupt context, and
212 * free_thread_stack() can be called in interrupt context,
213 * so cache the vm_struct.
216 tsk
->stack_vm_area
= find_vm_area(stack
);
219 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
222 return page
? page_address(page
) : NULL
;
226 static inline void free_thread_stack(struct task_struct
*tsk
)
228 #ifdef CONFIG_VMAP_STACK
229 if (task_stack_vm_area(tsk
)) {
233 local_irq_save(flags
);
234 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
235 if (this_cpu_read(cached_stacks
[i
]))
238 this_cpu_write(cached_stacks
[i
], tsk
->stack_vm_area
);
239 local_irq_restore(flags
);
242 local_irq_restore(flags
);
244 vfree_atomic(tsk
->stack
);
249 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
252 static struct kmem_cache
*thread_stack_cache
;
254 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
257 return kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
260 static void free_thread_stack(struct task_struct
*tsk
)
262 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
265 void thread_stack_cache_init(void)
267 thread_stack_cache
= kmem_cache_create("thread_stack", THREAD_SIZE
,
268 THREAD_SIZE
, 0, NULL
);
269 BUG_ON(thread_stack_cache
== NULL
);
274 /* SLAB cache for signal_struct structures (tsk->signal) */
275 static struct kmem_cache
*signal_cachep
;
277 /* SLAB cache for sighand_struct structures (tsk->sighand) */
278 struct kmem_cache
*sighand_cachep
;
280 /* SLAB cache for files_struct structures (tsk->files) */
281 struct kmem_cache
*files_cachep
;
283 /* SLAB cache for fs_struct structures (tsk->fs) */
284 struct kmem_cache
*fs_cachep
;
286 /* SLAB cache for vm_area_struct structures */
287 struct kmem_cache
*vm_area_cachep
;
289 /* SLAB cache for mm_struct structures (tsk->mm) */
290 static struct kmem_cache
*mm_cachep
;
292 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
294 void *stack
= task_stack_page(tsk
);
295 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
297 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
302 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
304 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
305 mod_zone_page_state(page_zone(vm
->pages
[i
]),
307 PAGE_SIZE
/ 1024 * account
);
310 /* All stack pages belong to the same memcg. */
311 memcg_kmem_update_page_stat(vm
->pages
[0], MEMCG_KERNEL_STACK_KB
,
312 account
* (THREAD_SIZE
/ 1024));
315 * All stack pages are in the same zone and belong to the
318 struct page
*first_page
= virt_to_page(stack
);
320 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
321 THREAD_SIZE
/ 1024 * account
);
323 memcg_kmem_update_page_stat(first_page
, MEMCG_KERNEL_STACK_KB
,
324 account
* (THREAD_SIZE
/ 1024));
328 static void release_task_stack(struct task_struct
*tsk
)
330 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
331 return; /* Better to leak the stack than to free prematurely */
333 account_kernel_stack(tsk
, -1);
334 arch_release_thread_stack(tsk
->stack
);
335 free_thread_stack(tsk
);
337 #ifdef CONFIG_VMAP_STACK
338 tsk
->stack_vm_area
= NULL
;
342 #ifdef CONFIG_THREAD_INFO_IN_TASK
343 void put_task_stack(struct task_struct
*tsk
)
345 if (atomic_dec_and_test(&tsk
->stack_refcount
))
346 release_task_stack(tsk
);
350 void free_task(struct task_struct
*tsk
)
352 #ifndef CONFIG_THREAD_INFO_IN_TASK
354 * The task is finally done with both the stack and thread_info,
357 release_task_stack(tsk
);
360 * If the task had a separate stack allocation, it should be gone
363 WARN_ON_ONCE(atomic_read(&tsk
->stack_refcount
) != 0);
365 rt_mutex_debug_task_free(tsk
);
366 ftrace_graph_exit_task(tsk
);
367 put_seccomp_filter(tsk
);
368 arch_release_task_struct(tsk
);
369 if (tsk
->flags
& PF_KTHREAD
)
370 free_kthread_struct(tsk
);
371 free_task_struct(tsk
);
373 EXPORT_SYMBOL(free_task
);
375 static inline void free_signal_struct(struct signal_struct
*sig
)
377 taskstats_tgid_free(sig
);
378 sched_autogroup_exit(sig
);
380 * __mmdrop is not safe to call from softirq context on x86 due to
381 * pgd_dtor so postpone it to the async context
384 mmdrop_async(sig
->oom_mm
);
385 kmem_cache_free(signal_cachep
, sig
);
388 static inline void put_signal_struct(struct signal_struct
*sig
)
390 if (atomic_dec_and_test(&sig
->sigcnt
))
391 free_signal_struct(sig
);
394 void __put_task_struct(struct task_struct
*tsk
)
396 WARN_ON(!tsk
->exit_state
);
397 WARN_ON(atomic_read(&tsk
->usage
));
398 WARN_ON(tsk
== current
);
402 security_task_free(tsk
);
404 delayacct_tsk_free(tsk
);
405 put_signal_struct(tsk
->signal
);
407 if (!profile_handoff_task(tsk
))
410 EXPORT_SYMBOL_GPL(__put_task_struct
);
412 void __init __weak
arch_task_cache_init(void) { }
417 static void set_max_threads(unsigned int max_threads_suggested
)
422 * The number of threads shall be limited such that the thread
423 * structures may only consume a small part of the available memory.
425 if (fls64(totalram_pages
) + fls64(PAGE_SIZE
) > 64)
426 threads
= MAX_THREADS
;
428 threads
= div64_u64((u64
) totalram_pages
* (u64
) PAGE_SIZE
,
429 (u64
) THREAD_SIZE
* 8UL);
431 if (threads
> max_threads_suggested
)
432 threads
= max_threads_suggested
;
434 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
437 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
438 /* Initialized by the architecture: */
439 int arch_task_struct_size __read_mostly
;
442 void __init
fork_init(void)
445 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
446 #ifndef ARCH_MIN_TASKALIGN
447 #define ARCH_MIN_TASKALIGN 0
449 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
451 /* create a slab on which task_structs can be allocated */
452 task_struct_cachep
= kmem_cache_create("task_struct",
453 arch_task_struct_size
, align
,
454 SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
, NULL
);
457 /* do the arch specific task caches init */
458 arch_task_cache_init();
460 set_max_threads(MAX_THREADS
);
462 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
463 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
464 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
465 init_task
.signal
->rlim
[RLIMIT_NPROC
];
467 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
468 init_user_ns
.ucount_max
[i
] = max_threads
/2;
472 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
473 struct task_struct
*src
)
479 void set_task_stack_end_magic(struct task_struct
*tsk
)
481 unsigned long *stackend
;
483 stackend
= end_of_stack(tsk
);
484 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
487 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
489 struct task_struct
*tsk
;
490 unsigned long *stack
;
491 struct vm_struct
*stack_vm_area
;
494 if (node
== NUMA_NO_NODE
)
495 node
= tsk_fork_get_node(orig
);
496 tsk
= alloc_task_struct_node(node
);
500 stack
= alloc_thread_stack_node(tsk
, node
);
504 stack_vm_area
= task_stack_vm_area(tsk
);
506 err
= arch_dup_task_struct(tsk
, orig
);
509 * arch_dup_task_struct() clobbers the stack-related fields. Make
510 * sure they're properly initialized before using any stack-related
514 #ifdef CONFIG_VMAP_STACK
515 tsk
->stack_vm_area
= stack_vm_area
;
517 #ifdef CONFIG_THREAD_INFO_IN_TASK
518 atomic_set(&tsk
->stack_refcount
, 1);
524 #ifdef CONFIG_SECCOMP
526 * We must handle setting up seccomp filters once we're under
527 * the sighand lock in case orig has changed between now and
528 * then. Until then, filter must be NULL to avoid messing up
529 * the usage counts on the error path calling free_task.
531 tsk
->seccomp
.filter
= NULL
;
534 setup_thread_stack(tsk
, orig
);
535 clear_user_return_notifier(tsk
);
536 clear_tsk_need_resched(tsk
);
537 set_task_stack_end_magic(tsk
);
539 #ifdef CONFIG_CC_STACKPROTECTOR
540 tsk
->stack_canary
= get_random_int();
544 * One for us, one for whoever does the "release_task()" (usually
547 atomic_set(&tsk
->usage
, 2);
548 #ifdef CONFIG_BLK_DEV_IO_TRACE
551 tsk
->splice_pipe
= NULL
;
552 tsk
->task_frag
.page
= NULL
;
553 tsk
->wake_q
.next
= NULL
;
555 account_kernel_stack(tsk
, 1);
562 free_thread_stack(tsk
);
564 free_task_struct(tsk
);
569 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
570 struct mm_struct
*oldmm
)
572 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
573 struct rb_node
**rb_link
, *rb_parent
;
575 unsigned long charge
;
578 uprobe_start_dup_mmap();
579 if (down_write_killable(&oldmm
->mmap_sem
)) {
581 goto fail_uprobe_end
;
583 flush_cache_dup_mm(oldmm
);
584 uprobe_dup_mmap(oldmm
, mm
);
586 * Not linked in yet - no deadlock potential:
588 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
590 /* No ordering required: file already has been exposed. */
591 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
593 mm
->total_vm
= oldmm
->total_vm
;
594 mm
->data_vm
= oldmm
->data_vm
;
595 mm
->exec_vm
= oldmm
->exec_vm
;
596 mm
->stack_vm
= oldmm
->stack_vm
;
598 rb_link
= &mm
->mm_rb
.rb_node
;
601 retval
= ksm_fork(mm
, oldmm
);
604 retval
= khugepaged_fork(mm
, oldmm
);
609 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
612 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
613 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
617 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
618 unsigned long len
= vma_pages(mpnt
);
620 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
624 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
628 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
629 retval
= vma_dup_policy(mpnt
, tmp
);
631 goto fail_nomem_policy
;
633 retval
= dup_userfaultfd(tmp
, &uf
);
635 goto fail_nomem_anon_vma_fork
;
636 if (anon_vma_fork(tmp
, mpnt
))
637 goto fail_nomem_anon_vma_fork
;
638 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
639 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
642 struct inode
*inode
= file_inode(file
);
643 struct address_space
*mapping
= file
->f_mapping
;
646 if (tmp
->vm_flags
& VM_DENYWRITE
)
647 atomic_dec(&inode
->i_writecount
);
648 i_mmap_lock_write(mapping
);
649 if (tmp
->vm_flags
& VM_SHARED
)
650 atomic_inc(&mapping
->i_mmap_writable
);
651 flush_dcache_mmap_lock(mapping
);
652 /* insert tmp into the share list, just after mpnt */
653 vma_interval_tree_insert_after(tmp
, mpnt
,
655 flush_dcache_mmap_unlock(mapping
);
656 i_mmap_unlock_write(mapping
);
660 * Clear hugetlb-related page reserves for children. This only
661 * affects MAP_PRIVATE mappings. Faults generated by the child
662 * are not guaranteed to succeed, even if read-only
664 if (is_vm_hugetlb_page(tmp
))
665 reset_vma_resv_huge_pages(tmp
);
668 * Link in the new vma and copy the page table entries.
671 pprev
= &tmp
->vm_next
;
675 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
676 rb_link
= &tmp
->vm_rb
.rb_right
;
677 rb_parent
= &tmp
->vm_rb
;
680 retval
= copy_page_range(mm
, oldmm
, mpnt
);
682 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
683 tmp
->vm_ops
->open(tmp
);
688 /* a new mm has just been created */
689 arch_dup_mmap(oldmm
, mm
);
692 up_write(&mm
->mmap_sem
);
694 up_write(&oldmm
->mmap_sem
);
695 dup_userfaultfd_complete(&uf
);
697 uprobe_end_dup_mmap();
699 fail_nomem_anon_vma_fork
:
700 mpol_put(vma_policy(tmp
));
702 kmem_cache_free(vm_area_cachep
, tmp
);
705 vm_unacct_memory(charge
);
709 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
711 mm
->pgd
= pgd_alloc(mm
);
712 if (unlikely(!mm
->pgd
))
717 static inline void mm_free_pgd(struct mm_struct
*mm
)
719 pgd_free(mm
, mm
->pgd
);
722 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
724 down_write(&oldmm
->mmap_sem
);
725 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
726 up_write(&oldmm
->mmap_sem
);
729 #define mm_alloc_pgd(mm) (0)
730 #define mm_free_pgd(mm)
731 #endif /* CONFIG_MMU */
733 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
735 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
736 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
738 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
740 static int __init
coredump_filter_setup(char *s
)
742 default_dump_filter
=
743 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
744 MMF_DUMP_FILTER_MASK
;
748 __setup("coredump_filter=", coredump_filter_setup
);
750 #include <linux/init_task.h>
752 static void mm_init_aio(struct mm_struct
*mm
)
755 spin_lock_init(&mm
->ioctx_lock
);
756 mm
->ioctx_table
= NULL
;
760 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
767 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
768 struct user_namespace
*user_ns
)
772 mm
->vmacache_seqnum
= 0;
773 atomic_set(&mm
->mm_users
, 1);
774 atomic_set(&mm
->mm_count
, 1);
775 init_rwsem(&mm
->mmap_sem
);
776 INIT_LIST_HEAD(&mm
->mmlist
);
777 mm
->core_state
= NULL
;
778 atomic_long_set(&mm
->nr_ptes
, 0);
783 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
784 spin_lock_init(&mm
->page_table_lock
);
787 mm_init_owner(mm
, p
);
788 mmu_notifier_mm_init(mm
);
789 clear_tlb_flush_pending(mm
);
790 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
791 mm
->pmd_huge_pte
= NULL
;
795 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
796 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
798 mm
->flags
= default_dump_filter
;
802 if (mm_alloc_pgd(mm
))
805 if (init_new_context(p
, mm
))
808 mm
->user_ns
= get_user_ns(user_ns
);
818 static void check_mm(struct mm_struct
*mm
)
822 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
823 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
826 printk(KERN_ALERT
"BUG: Bad rss-counter state "
827 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
830 if (atomic_long_read(&mm
->nr_ptes
))
831 pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
832 atomic_long_read(&mm
->nr_ptes
));
834 pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
837 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
838 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
843 * Allocate and initialize an mm_struct.
845 struct mm_struct
*mm_alloc(void)
847 struct mm_struct
*mm
;
853 memset(mm
, 0, sizeof(*mm
));
854 return mm_init(mm
, current
, current_user_ns());
858 * Called when the last reference to the mm
859 * is dropped: either by a lazy thread or by
860 * mmput. Free the page directory and the mm.
862 void __mmdrop(struct mm_struct
*mm
)
864 BUG_ON(mm
== &init_mm
);
867 mmu_notifier_mm_destroy(mm
);
869 put_user_ns(mm
->user_ns
);
872 EXPORT_SYMBOL_GPL(__mmdrop
);
874 static inline void __mmput(struct mm_struct
*mm
)
876 VM_BUG_ON(atomic_read(&mm
->mm_users
));
878 uprobe_clear_state(mm
);
881 khugepaged_exit(mm
); /* must run before exit_mmap */
883 mm_put_huge_zero_page(mm
);
884 set_mm_exe_file(mm
, NULL
);
885 if (!list_empty(&mm
->mmlist
)) {
886 spin_lock(&mmlist_lock
);
887 list_del(&mm
->mmlist
);
888 spin_unlock(&mmlist_lock
);
891 module_put(mm
->binfmt
->module
);
892 set_bit(MMF_OOM_SKIP
, &mm
->flags
);
897 * Decrement the use count and release all resources for an mm.
899 void mmput(struct mm_struct
*mm
)
903 if (atomic_dec_and_test(&mm
->mm_users
))
906 EXPORT_SYMBOL_GPL(mmput
);
909 static void mmput_async_fn(struct work_struct
*work
)
911 struct mm_struct
*mm
= container_of(work
, struct mm_struct
, async_put_work
);
915 void mmput_async(struct mm_struct
*mm
)
917 if (atomic_dec_and_test(&mm
->mm_users
)) {
918 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
919 schedule_work(&mm
->async_put_work
);
925 * set_mm_exe_file - change a reference to the mm's executable file
927 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
929 * Main users are mmput() and sys_execve(). Callers prevent concurrent
930 * invocations: in mmput() nobody alive left, in execve task is single
931 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
932 * mm->exe_file, but does so without using set_mm_exe_file() in order
933 * to do avoid the need for any locks.
935 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
937 struct file
*old_exe_file
;
940 * It is safe to dereference the exe_file without RCU as
941 * this function is only called if nobody else can access
942 * this mm -- see comment above for justification.
944 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
947 get_file(new_exe_file
);
948 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
954 * get_mm_exe_file - acquire a reference to the mm's executable file
956 * Returns %NULL if mm has no associated executable file.
957 * User must release file via fput().
959 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
961 struct file
*exe_file
;
964 exe_file
= rcu_dereference(mm
->exe_file
);
965 if (exe_file
&& !get_file_rcu(exe_file
))
970 EXPORT_SYMBOL(get_mm_exe_file
);
973 * get_task_exe_file - acquire a reference to the task's executable file
975 * Returns %NULL if task's mm (if any) has no associated executable file or
976 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
977 * User must release file via fput().
979 struct file
*get_task_exe_file(struct task_struct
*task
)
981 struct file
*exe_file
= NULL
;
982 struct mm_struct
*mm
;
987 if (!(task
->flags
& PF_KTHREAD
))
988 exe_file
= get_mm_exe_file(mm
);
993 EXPORT_SYMBOL(get_task_exe_file
);
996 * get_task_mm - acquire a reference to the task's mm
998 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
999 * this kernel workthread has transiently adopted a user mm with use_mm,
1000 * to do its AIO) is not set and if so returns a reference to it, after
1001 * bumping up the use count. User must release the mm via mmput()
1002 * after use. Typically used by /proc and ptrace.
1004 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1006 struct mm_struct
*mm
;
1011 if (task
->flags
& PF_KTHREAD
)
1019 EXPORT_SYMBOL_GPL(get_task_mm
);
1021 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1023 struct mm_struct
*mm
;
1026 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
1028 return ERR_PTR(err
);
1030 mm
= get_task_mm(task
);
1031 if (mm
&& mm
!= current
->mm
&&
1032 !ptrace_may_access(task
, mode
)) {
1034 mm
= ERR_PTR(-EACCES
);
1036 mutex_unlock(&task
->signal
->cred_guard_mutex
);
1041 static void complete_vfork_done(struct task_struct
*tsk
)
1043 struct completion
*vfork
;
1046 vfork
= tsk
->vfork_done
;
1047 if (likely(vfork
)) {
1048 tsk
->vfork_done
= NULL
;
1054 static int wait_for_vfork_done(struct task_struct
*child
,
1055 struct completion
*vfork
)
1059 freezer_do_not_count();
1060 killed
= wait_for_completion_killable(vfork
);
1065 child
->vfork_done
= NULL
;
1069 put_task_struct(child
);
1073 /* Please note the differences between mmput and mm_release.
1074 * mmput is called whenever we stop holding onto a mm_struct,
1075 * error success whatever.
1077 * mm_release is called after a mm_struct has been removed
1078 * from the current process.
1080 * This difference is important for error handling, when we
1081 * only half set up a mm_struct for a new process and need to restore
1082 * the old one. Because we mmput the new mm_struct before
1083 * restoring the old one. . .
1084 * Eric Biederman 10 January 1998
1086 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1088 /* Get rid of any futexes when releasing the mm */
1090 if (unlikely(tsk
->robust_list
)) {
1091 exit_robust_list(tsk
);
1092 tsk
->robust_list
= NULL
;
1094 #ifdef CONFIG_COMPAT
1095 if (unlikely(tsk
->compat_robust_list
)) {
1096 compat_exit_robust_list(tsk
);
1097 tsk
->compat_robust_list
= NULL
;
1100 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1101 exit_pi_state_list(tsk
);
1104 uprobe_free_utask(tsk
);
1106 /* Get rid of any cached register state */
1107 deactivate_mm(tsk
, mm
);
1110 * Signal userspace if we're not exiting with a core dump
1111 * because we want to leave the value intact for debugging
1114 if (tsk
->clear_child_tid
) {
1115 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1116 atomic_read(&mm
->mm_users
) > 1) {
1118 * We don't check the error code - if userspace has
1119 * not set up a proper pointer then tough luck.
1121 put_user(0, tsk
->clear_child_tid
);
1122 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1125 tsk
->clear_child_tid
= NULL
;
1129 * All done, finally we can wake up parent and return this mm to him.
1130 * Also kthread_stop() uses this completion for synchronization.
1132 if (tsk
->vfork_done
)
1133 complete_vfork_done(tsk
);
1137 * Allocate a new mm structure and copy contents from the
1138 * mm structure of the passed in task structure.
1140 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
1142 struct mm_struct
*mm
, *oldmm
= current
->mm
;
1149 memcpy(mm
, oldmm
, sizeof(*mm
));
1151 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1154 err
= dup_mmap(mm
, oldmm
);
1158 mm
->hiwater_rss
= get_mm_rss(mm
);
1159 mm
->hiwater_vm
= mm
->total_vm
;
1161 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1167 /* don't put binfmt in mmput, we haven't got module yet */
1175 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1177 struct mm_struct
*mm
, *oldmm
;
1180 tsk
->min_flt
= tsk
->maj_flt
= 0;
1181 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1182 #ifdef CONFIG_DETECT_HUNG_TASK
1183 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1187 tsk
->active_mm
= NULL
;
1190 * Are we cloning a kernel thread?
1192 * We need to steal a active VM for that..
1194 oldmm
= current
->mm
;
1198 /* initialize the new vmacache entries */
1199 vmacache_flush(tsk
);
1201 if (clone_flags
& CLONE_VM
) {
1214 tsk
->active_mm
= mm
;
1221 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1223 struct fs_struct
*fs
= current
->fs
;
1224 if (clone_flags
& CLONE_FS
) {
1225 /* tsk->fs is already what we want */
1226 spin_lock(&fs
->lock
);
1228 spin_unlock(&fs
->lock
);
1232 spin_unlock(&fs
->lock
);
1235 tsk
->fs
= copy_fs_struct(fs
);
1241 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1243 struct files_struct
*oldf
, *newf
;
1247 * A background process may not have any files ...
1249 oldf
= current
->files
;
1253 if (clone_flags
& CLONE_FILES
) {
1254 atomic_inc(&oldf
->count
);
1258 newf
= dup_fd(oldf
, &error
);
1268 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1271 struct io_context
*ioc
= current
->io_context
;
1272 struct io_context
*new_ioc
;
1277 * Share io context with parent, if CLONE_IO is set
1279 if (clone_flags
& CLONE_IO
) {
1281 tsk
->io_context
= ioc
;
1282 } else if (ioprio_valid(ioc
->ioprio
)) {
1283 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1284 if (unlikely(!new_ioc
))
1287 new_ioc
->ioprio
= ioc
->ioprio
;
1288 put_io_context(new_ioc
);
1294 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1296 struct sighand_struct
*sig
;
1298 if (clone_flags
& CLONE_SIGHAND
) {
1299 atomic_inc(¤t
->sighand
->count
);
1302 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1303 rcu_assign_pointer(tsk
->sighand
, sig
);
1307 atomic_set(&sig
->count
, 1);
1308 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1312 void __cleanup_sighand(struct sighand_struct
*sighand
)
1314 if (atomic_dec_and_test(&sighand
->count
)) {
1315 signalfd_cleanup(sighand
);
1317 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
1318 * without an RCU grace period, see __lock_task_sighand().
1320 kmem_cache_free(sighand_cachep
, sighand
);
1324 #ifdef CONFIG_POSIX_TIMERS
1326 * Initialize POSIX timer handling for a thread group.
1328 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1330 unsigned long cpu_limit
;
1332 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1333 if (cpu_limit
!= RLIM_INFINITY
) {
1334 sig
->cputime_expires
.prof_exp
= cpu_limit
* NSEC_PER_SEC
;
1335 sig
->cputimer
.running
= true;
1338 /* The timer lists. */
1339 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1340 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1341 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1344 static inline void posix_cpu_timers_init_group(struct signal_struct
*sig
) { }
1347 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1349 struct signal_struct
*sig
;
1351 if (clone_flags
& CLONE_THREAD
)
1354 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1359 sig
->nr_threads
= 1;
1360 atomic_set(&sig
->live
, 1);
1361 atomic_set(&sig
->sigcnt
, 1);
1363 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1364 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1365 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1367 init_waitqueue_head(&sig
->wait_chldexit
);
1368 sig
->curr_target
= tsk
;
1369 init_sigpending(&sig
->shared_pending
);
1370 seqlock_init(&sig
->stats_lock
);
1371 prev_cputime_init(&sig
->prev_cputime
);
1373 #ifdef CONFIG_POSIX_TIMERS
1374 INIT_LIST_HEAD(&sig
->posix_timers
);
1375 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1376 sig
->real_timer
.function
= it_real_fn
;
1379 task_lock(current
->group_leader
);
1380 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1381 task_unlock(current
->group_leader
);
1383 posix_cpu_timers_init_group(sig
);
1385 tty_audit_fork(sig
);
1386 sched_autogroup_fork(sig
);
1388 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1389 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1391 mutex_init(&sig
->cred_guard_mutex
);
1396 static void copy_seccomp(struct task_struct
*p
)
1398 #ifdef CONFIG_SECCOMP
1400 * Must be called with sighand->lock held, which is common to
1401 * all threads in the group. Holding cred_guard_mutex is not
1402 * needed because this new task is not yet running and cannot
1405 assert_spin_locked(¤t
->sighand
->siglock
);
1407 /* Ref-count the new filter user, and assign it. */
1408 get_seccomp_filter(current
);
1409 p
->seccomp
= current
->seccomp
;
1412 * Explicitly enable no_new_privs here in case it got set
1413 * between the task_struct being duplicated and holding the
1414 * sighand lock. The seccomp state and nnp must be in sync.
1416 if (task_no_new_privs(current
))
1417 task_set_no_new_privs(p
);
1420 * If the parent gained a seccomp mode after copying thread
1421 * flags and between before we held the sighand lock, we have
1422 * to manually enable the seccomp thread flag here.
1424 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1425 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1429 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1431 current
->clear_child_tid
= tidptr
;
1433 return task_pid_vnr(current
);
1436 static void rt_mutex_init_task(struct task_struct
*p
)
1438 raw_spin_lock_init(&p
->pi_lock
);
1439 #ifdef CONFIG_RT_MUTEXES
1440 p
->pi_waiters
= RB_ROOT
;
1441 p
->pi_waiters_leftmost
= NULL
;
1442 p
->pi_top_task
= NULL
;
1443 p
->pi_blocked_on
= NULL
;
1447 #ifdef CONFIG_POSIX_TIMERS
1449 * Initialize POSIX timer handling for a single task.
1451 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1453 tsk
->cputime_expires
.prof_exp
= 0;
1454 tsk
->cputime_expires
.virt_exp
= 0;
1455 tsk
->cputime_expires
.sched_exp
= 0;
1456 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1457 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1458 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1461 static inline void posix_cpu_timers_init(struct task_struct
*tsk
) { }
1465 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1467 task
->pids
[type
].pid
= pid
;
1470 static inline void rcu_copy_process(struct task_struct
*p
)
1472 #ifdef CONFIG_PREEMPT_RCU
1473 p
->rcu_read_lock_nesting
= 0;
1474 p
->rcu_read_unlock_special
.s
= 0;
1475 p
->rcu_blocked_node
= NULL
;
1476 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1477 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1478 #ifdef CONFIG_TASKS_RCU
1479 p
->rcu_tasks_holdout
= false;
1480 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1481 p
->rcu_tasks_idle_cpu
= -1;
1482 #endif /* #ifdef CONFIG_TASKS_RCU */
1486 * This creates a new process as a copy of the old one,
1487 * but does not actually start it yet.
1489 * It copies the registers, and all the appropriate
1490 * parts of the process environment (as per the clone
1491 * flags). The actual kick-off is left to the caller.
1493 static __latent_entropy
struct task_struct
*copy_process(
1494 unsigned long clone_flags
,
1495 unsigned long stack_start
,
1496 unsigned long stack_size
,
1497 int __user
*child_tidptr
,
1504 struct task_struct
*p
;
1506 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1507 return ERR_PTR(-EINVAL
);
1509 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1510 return ERR_PTR(-EINVAL
);
1513 * Thread groups must share signals as well, and detached threads
1514 * can only be started up within the thread group.
1516 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1517 return ERR_PTR(-EINVAL
);
1520 * Shared signal handlers imply shared VM. By way of the above,
1521 * thread groups also imply shared VM. Blocking this case allows
1522 * for various simplifications in other code.
1524 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1525 return ERR_PTR(-EINVAL
);
1528 * Siblings of global init remain as zombies on exit since they are
1529 * not reaped by their parent (swapper). To solve this and to avoid
1530 * multi-rooted process trees, prevent global and container-inits
1531 * from creating siblings.
1533 if ((clone_flags
& CLONE_PARENT
) &&
1534 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1535 return ERR_PTR(-EINVAL
);
1538 * If the new process will be in a different pid or user namespace
1539 * do not allow it to share a thread group with the forking task.
1541 if (clone_flags
& CLONE_THREAD
) {
1542 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1543 (task_active_pid_ns(current
) !=
1544 current
->nsproxy
->pid_ns_for_children
))
1545 return ERR_PTR(-EINVAL
);
1548 retval
= security_task_create(clone_flags
);
1553 p
= dup_task_struct(current
, node
);
1557 ftrace_graph_init_task(p
);
1559 rt_mutex_init_task(p
);
1561 #ifdef CONFIG_PROVE_LOCKING
1562 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1563 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1566 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1567 task_rlimit(p
, RLIMIT_NPROC
)) {
1568 if (p
->real_cred
->user
!= INIT_USER
&&
1569 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1572 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1574 retval
= copy_creds(p
, clone_flags
);
1579 * If multiple threads are within copy_process(), then this check
1580 * triggers too late. This doesn't hurt, the check is only there
1581 * to stop root fork bombs.
1584 if (nr_threads
>= max_threads
)
1585 goto bad_fork_cleanup_count
;
1587 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1588 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1589 p
->flags
|= PF_FORKNOEXEC
;
1590 INIT_LIST_HEAD(&p
->children
);
1591 INIT_LIST_HEAD(&p
->sibling
);
1592 rcu_copy_process(p
);
1593 p
->vfork_done
= NULL
;
1594 spin_lock_init(&p
->alloc_lock
);
1596 init_sigpending(&p
->pending
);
1598 p
->utime
= p
->stime
= p
->gtime
= 0;
1599 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1600 p
->utimescaled
= p
->stimescaled
= 0;
1602 prev_cputime_init(&p
->prev_cputime
);
1604 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1605 seqcount_init(&p
->vtime_seqcount
);
1607 p
->vtime_snap_whence
= VTIME_INACTIVE
;
1610 #if defined(SPLIT_RSS_COUNTING)
1611 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1614 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1616 task_io_accounting_init(&p
->ioac
);
1617 acct_clear_integrals(p
);
1619 posix_cpu_timers_init(p
);
1621 p
->start_time
= ktime_get_ns();
1622 p
->real_start_time
= ktime_get_boot_ns();
1623 p
->io_context
= NULL
;
1624 p
->audit_context
= NULL
;
1627 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1628 if (IS_ERR(p
->mempolicy
)) {
1629 retval
= PTR_ERR(p
->mempolicy
);
1630 p
->mempolicy
= NULL
;
1631 goto bad_fork_cleanup_threadgroup_lock
;
1634 #ifdef CONFIG_CPUSETS
1635 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1636 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1637 seqcount_init(&p
->mems_allowed_seq
);
1639 #ifdef CONFIG_TRACE_IRQFLAGS
1641 p
->hardirqs_enabled
= 0;
1642 p
->hardirq_enable_ip
= 0;
1643 p
->hardirq_enable_event
= 0;
1644 p
->hardirq_disable_ip
= _THIS_IP_
;
1645 p
->hardirq_disable_event
= 0;
1646 p
->softirqs_enabled
= 1;
1647 p
->softirq_enable_ip
= _THIS_IP_
;
1648 p
->softirq_enable_event
= 0;
1649 p
->softirq_disable_ip
= 0;
1650 p
->softirq_disable_event
= 0;
1651 p
->hardirq_context
= 0;
1652 p
->softirq_context
= 0;
1655 p
->pagefault_disabled
= 0;
1657 #ifdef CONFIG_LOCKDEP
1658 p
->lockdep_depth
= 0; /* no locks held yet */
1659 p
->curr_chain_key
= 0;
1660 p
->lockdep_recursion
= 0;
1663 #ifdef CONFIG_DEBUG_MUTEXES
1664 p
->blocked_on
= NULL
; /* not blocked yet */
1666 #ifdef CONFIG_BCACHE
1667 p
->sequential_io
= 0;
1668 p
->sequential_io_avg
= 0;
1671 /* Perform scheduler related setup. Assign this task to a CPU. */
1672 retval
= sched_fork(clone_flags
, p
);
1674 goto bad_fork_cleanup_policy
;
1676 retval
= perf_event_init_task(p
);
1678 goto bad_fork_cleanup_policy
;
1679 retval
= audit_alloc(p
);
1681 goto bad_fork_cleanup_perf
;
1682 /* copy all the process information */
1684 retval
= security_task_alloc(p
, clone_flags
);
1686 goto bad_fork_cleanup_audit
;
1687 retval
= copy_semundo(clone_flags
, p
);
1689 goto bad_fork_cleanup_security
;
1690 retval
= copy_files(clone_flags
, p
);
1692 goto bad_fork_cleanup_semundo
;
1693 retval
= copy_fs(clone_flags
, p
);
1695 goto bad_fork_cleanup_files
;
1696 retval
= copy_sighand(clone_flags
, p
);
1698 goto bad_fork_cleanup_fs
;
1699 retval
= copy_signal(clone_flags
, p
);
1701 goto bad_fork_cleanup_sighand
;
1702 retval
= copy_mm(clone_flags
, p
);
1704 goto bad_fork_cleanup_signal
;
1705 retval
= copy_namespaces(clone_flags
, p
);
1707 goto bad_fork_cleanup_mm
;
1708 retval
= copy_io(clone_flags
, p
);
1710 goto bad_fork_cleanup_namespaces
;
1711 retval
= copy_thread_tls(clone_flags
, stack_start
, stack_size
, p
, tls
);
1713 goto bad_fork_cleanup_io
;
1715 if (pid
!= &init_struct_pid
) {
1716 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1718 retval
= PTR_ERR(pid
);
1719 goto bad_fork_cleanup_thread
;
1723 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1725 * Clear TID on mm_release()?
1727 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1732 p
->robust_list
= NULL
;
1733 #ifdef CONFIG_COMPAT
1734 p
->compat_robust_list
= NULL
;
1736 INIT_LIST_HEAD(&p
->pi_state_list
);
1737 p
->pi_state_cache
= NULL
;
1740 * sigaltstack should be cleared when sharing the same VM
1742 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1746 * Syscall tracing and stepping should be turned off in the
1747 * child regardless of CLONE_PTRACE.
1749 user_disable_single_step(p
);
1750 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1751 #ifdef TIF_SYSCALL_EMU
1752 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1754 clear_all_latency_tracing(p
);
1756 /* ok, now we should be set up.. */
1757 p
->pid
= pid_nr(pid
);
1758 if (clone_flags
& CLONE_THREAD
) {
1759 p
->exit_signal
= -1;
1760 p
->group_leader
= current
->group_leader
;
1761 p
->tgid
= current
->tgid
;
1763 if (clone_flags
& CLONE_PARENT
)
1764 p
->exit_signal
= current
->group_leader
->exit_signal
;
1766 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1767 p
->group_leader
= p
;
1772 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1773 p
->dirty_paused_when
= 0;
1775 p
->pdeath_signal
= 0;
1776 INIT_LIST_HEAD(&p
->thread_group
);
1777 p
->task_works
= NULL
;
1779 cgroup_threadgroup_change_begin(current
);
1781 * Ensure that the cgroup subsystem policies allow the new process to be
1782 * forked. It should be noted the the new process's css_set can be changed
1783 * between here and cgroup_post_fork() if an organisation operation is in
1786 retval
= cgroup_can_fork(p
);
1788 goto bad_fork_free_pid
;
1791 * Make it visible to the rest of the system, but dont wake it up yet.
1792 * Need tasklist lock for parent etc handling!
1794 write_lock_irq(&tasklist_lock
);
1796 /* CLONE_PARENT re-uses the old parent */
1797 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1798 p
->real_parent
= current
->real_parent
;
1799 p
->parent_exec_id
= current
->parent_exec_id
;
1801 p
->real_parent
= current
;
1802 p
->parent_exec_id
= current
->self_exec_id
;
1805 klp_copy_process(p
);
1807 spin_lock(¤t
->sighand
->siglock
);
1810 * Copy seccomp details explicitly here, in case they were changed
1811 * before holding sighand lock.
1816 * Process group and session signals need to be delivered to just the
1817 * parent before the fork or both the parent and the child after the
1818 * fork. Restart if a signal comes in before we add the new process to
1819 * it's process group.
1820 * A fatal signal pending means that current will exit, so the new
1821 * thread can't slip out of an OOM kill (or normal SIGKILL).
1823 recalc_sigpending();
1824 if (signal_pending(current
)) {
1825 spin_unlock(¤t
->sighand
->siglock
);
1826 write_unlock_irq(&tasklist_lock
);
1827 retval
= -ERESTARTNOINTR
;
1828 goto bad_fork_cancel_cgroup
;
1831 if (likely(p
->pid
)) {
1832 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1834 init_task_pid(p
, PIDTYPE_PID
, pid
);
1835 if (thread_group_leader(p
)) {
1836 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1837 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1839 if (is_child_reaper(pid
)) {
1840 ns_of_pid(pid
)->child_reaper
= p
;
1841 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1844 p
->signal
->leader_pid
= pid
;
1845 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1847 * Inherit has_child_subreaper flag under the same
1848 * tasklist_lock with adding child to the process tree
1849 * for propagate_has_child_subreaper optimization.
1851 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
1852 p
->real_parent
->signal
->is_child_subreaper
;
1853 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1854 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1855 attach_pid(p
, PIDTYPE_PGID
);
1856 attach_pid(p
, PIDTYPE_SID
);
1857 __this_cpu_inc(process_counts
);
1859 current
->signal
->nr_threads
++;
1860 atomic_inc(¤t
->signal
->live
);
1861 atomic_inc(¤t
->signal
->sigcnt
);
1862 list_add_tail_rcu(&p
->thread_group
,
1863 &p
->group_leader
->thread_group
);
1864 list_add_tail_rcu(&p
->thread_node
,
1865 &p
->signal
->thread_head
);
1867 attach_pid(p
, PIDTYPE_PID
);
1872 spin_unlock(¤t
->sighand
->siglock
);
1873 syscall_tracepoint_update(p
);
1874 write_unlock_irq(&tasklist_lock
);
1876 proc_fork_connector(p
);
1877 cgroup_post_fork(p
);
1878 cgroup_threadgroup_change_end(current
);
1881 trace_task_newtask(p
, clone_flags
);
1882 uprobe_copy_process(p
, clone_flags
);
1886 bad_fork_cancel_cgroup
:
1887 cgroup_cancel_fork(p
);
1889 cgroup_threadgroup_change_end(current
);
1890 if (pid
!= &init_struct_pid
)
1892 bad_fork_cleanup_thread
:
1894 bad_fork_cleanup_io
:
1897 bad_fork_cleanup_namespaces
:
1898 exit_task_namespaces(p
);
1899 bad_fork_cleanup_mm
:
1902 bad_fork_cleanup_signal
:
1903 if (!(clone_flags
& CLONE_THREAD
))
1904 free_signal_struct(p
->signal
);
1905 bad_fork_cleanup_sighand
:
1906 __cleanup_sighand(p
->sighand
);
1907 bad_fork_cleanup_fs
:
1908 exit_fs(p
); /* blocking */
1909 bad_fork_cleanup_files
:
1910 exit_files(p
); /* blocking */
1911 bad_fork_cleanup_semundo
:
1913 bad_fork_cleanup_security
:
1914 security_task_free(p
);
1915 bad_fork_cleanup_audit
:
1917 bad_fork_cleanup_perf
:
1918 perf_event_free_task(p
);
1919 bad_fork_cleanup_policy
:
1921 mpol_put(p
->mempolicy
);
1922 bad_fork_cleanup_threadgroup_lock
:
1924 delayacct_tsk_free(p
);
1925 bad_fork_cleanup_count
:
1926 atomic_dec(&p
->cred
->user
->processes
);
1929 p
->state
= TASK_DEAD
;
1933 return ERR_PTR(retval
);
1936 static inline void init_idle_pids(struct pid_link
*links
)
1940 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1941 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1942 links
[type
].pid
= &init_struct_pid
;
1946 struct task_struct
*fork_idle(int cpu
)
1948 struct task_struct
*task
;
1949 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0, 0,
1951 if (!IS_ERR(task
)) {
1952 init_idle_pids(task
->pids
);
1953 init_idle(task
, cpu
);
1960 * Ok, this is the main fork-routine.
1962 * It copies the process, and if successful kick-starts
1963 * it and waits for it to finish using the VM if required.
1965 long _do_fork(unsigned long clone_flags
,
1966 unsigned long stack_start
,
1967 unsigned long stack_size
,
1968 int __user
*parent_tidptr
,
1969 int __user
*child_tidptr
,
1972 struct task_struct
*p
;
1977 * Determine whether and which event to report to ptracer. When
1978 * called from kernel_thread or CLONE_UNTRACED is explicitly
1979 * requested, no event is reported; otherwise, report if the event
1980 * for the type of forking is enabled.
1982 if (!(clone_flags
& CLONE_UNTRACED
)) {
1983 if (clone_flags
& CLONE_VFORK
)
1984 trace
= PTRACE_EVENT_VFORK
;
1985 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1986 trace
= PTRACE_EVENT_CLONE
;
1988 trace
= PTRACE_EVENT_FORK
;
1990 if (likely(!ptrace_event_enabled(current
, trace
)))
1994 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1995 child_tidptr
, NULL
, trace
, tls
, NUMA_NO_NODE
);
1996 add_latent_entropy();
1998 * Do this prior waking up the new thread - the thread pointer
1999 * might get invalid after that point, if the thread exits quickly.
2002 struct completion vfork
;
2005 trace_sched_process_fork(current
, p
);
2007 pid
= get_task_pid(p
, PIDTYPE_PID
);
2010 if (clone_flags
& CLONE_PARENT_SETTID
)
2011 put_user(nr
, parent_tidptr
);
2013 if (clone_flags
& CLONE_VFORK
) {
2014 p
->vfork_done
= &vfork
;
2015 init_completion(&vfork
);
2019 wake_up_new_task(p
);
2021 /* forking complete and child started to run, tell ptracer */
2022 if (unlikely(trace
))
2023 ptrace_event_pid(trace
, pid
);
2025 if (clone_flags
& CLONE_VFORK
) {
2026 if (!wait_for_vfork_done(p
, &vfork
))
2027 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2037 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2038 /* For compatibility with architectures that call do_fork directly rather than
2039 * using the syscall entry points below. */
2040 long do_fork(unsigned long clone_flags
,
2041 unsigned long stack_start
,
2042 unsigned long stack_size
,
2043 int __user
*parent_tidptr
,
2044 int __user
*child_tidptr
)
2046 return _do_fork(clone_flags
, stack_start
, stack_size
,
2047 parent_tidptr
, child_tidptr
, 0);
2052 * Create a kernel thread.
2054 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2056 return _do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
2057 (unsigned long)arg
, NULL
, NULL
, 0);
2060 #ifdef __ARCH_WANT_SYS_FORK
2061 SYSCALL_DEFINE0(fork
)
2064 return _do_fork(SIGCHLD
, 0, 0, NULL
, NULL
, 0);
2066 /* can not support in nommu mode */
2072 #ifdef __ARCH_WANT_SYS_VFORK
2073 SYSCALL_DEFINE0(vfork
)
2075 return _do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
2080 #ifdef __ARCH_WANT_SYS_CLONE
2081 #ifdef CONFIG_CLONE_BACKWARDS
2082 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2083 int __user
*, parent_tidptr
,
2085 int __user
*, child_tidptr
)
2086 #elif defined(CONFIG_CLONE_BACKWARDS2)
2087 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2088 int __user
*, parent_tidptr
,
2089 int __user
*, child_tidptr
,
2091 #elif defined(CONFIG_CLONE_BACKWARDS3)
2092 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2094 int __user
*, parent_tidptr
,
2095 int __user
*, child_tidptr
,
2098 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2099 int __user
*, parent_tidptr
,
2100 int __user
*, child_tidptr
,
2104 return _do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
, tls
);
2108 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2110 struct task_struct
*leader
, *parent
, *child
;
2113 read_lock(&tasklist_lock
);
2114 leader
= top
= top
->group_leader
;
2116 for_each_thread(leader
, parent
) {
2117 list_for_each_entry(child
, &parent
->children
, sibling
) {
2118 res
= visitor(child
, data
);
2130 if (leader
!= top
) {
2132 parent
= child
->real_parent
;
2133 leader
= parent
->group_leader
;
2137 read_unlock(&tasklist_lock
);
2140 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2141 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2144 static void sighand_ctor(void *data
)
2146 struct sighand_struct
*sighand
= data
;
2148 spin_lock_init(&sighand
->siglock
);
2149 init_waitqueue_head(&sighand
->signalfd_wqh
);
2152 void __init
proc_caches_init(void)
2154 sighand_cachep
= kmem_cache_create("sighand_cache",
2155 sizeof(struct sighand_struct
), 0,
2156 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
2157 SLAB_NOTRACK
|SLAB_ACCOUNT
, sighand_ctor
);
2158 signal_cachep
= kmem_cache_create("signal_cache",
2159 sizeof(struct signal_struct
), 0,
2160 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2162 files_cachep
= kmem_cache_create("files_cache",
2163 sizeof(struct files_struct
), 0,
2164 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2166 fs_cachep
= kmem_cache_create("fs_cache",
2167 sizeof(struct fs_struct
), 0,
2168 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2171 * FIXME! The "sizeof(struct mm_struct)" currently includes the
2172 * whole struct cpumask for the OFFSTACK case. We could change
2173 * this to *only* allocate as much of it as required by the
2174 * maximum number of CPU's we can ever have. The cpumask_allocation
2175 * is at the end of the structure, exactly for that reason.
2177 mm_cachep
= kmem_cache_create("mm_struct",
2178 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
2179 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2181 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2183 nsproxy_cache_init();
2187 * Check constraints on flags passed to the unshare system call.
2189 static int check_unshare_flags(unsigned long unshare_flags
)
2191 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2192 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2193 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2194 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
))
2197 * Not implemented, but pretend it works if there is nothing
2198 * to unshare. Note that unsharing the address space or the
2199 * signal handlers also need to unshare the signal queues (aka
2202 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2203 if (!thread_group_empty(current
))
2206 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2207 if (atomic_read(¤t
->sighand
->count
) > 1)
2210 if (unshare_flags
& CLONE_VM
) {
2211 if (!current_is_single_threaded())
2219 * Unshare the filesystem structure if it is being shared
2221 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2223 struct fs_struct
*fs
= current
->fs
;
2225 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2228 /* don't need lock here; in the worst case we'll do useless copy */
2232 *new_fsp
= copy_fs_struct(fs
);
2240 * Unshare file descriptor table if it is being shared
2242 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2244 struct files_struct
*fd
= current
->files
;
2247 if ((unshare_flags
& CLONE_FILES
) &&
2248 (fd
&& atomic_read(&fd
->count
) > 1)) {
2249 *new_fdp
= dup_fd(fd
, &error
);
2258 * unshare allows a process to 'unshare' part of the process
2259 * context which was originally shared using clone. copy_*
2260 * functions used by do_fork() cannot be used here directly
2261 * because they modify an inactive task_struct that is being
2262 * constructed. Here we are modifying the current, active,
2265 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
2267 struct fs_struct
*fs
, *new_fs
= NULL
;
2268 struct files_struct
*fd
, *new_fd
= NULL
;
2269 struct cred
*new_cred
= NULL
;
2270 struct nsproxy
*new_nsproxy
= NULL
;
2275 * If unsharing a user namespace must also unshare the thread group
2276 * and unshare the filesystem root and working directories.
2278 if (unshare_flags
& CLONE_NEWUSER
)
2279 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2281 * If unsharing vm, must also unshare signal handlers.
2283 if (unshare_flags
& CLONE_VM
)
2284 unshare_flags
|= CLONE_SIGHAND
;
2286 * If unsharing a signal handlers, must also unshare the signal queues.
2288 if (unshare_flags
& CLONE_SIGHAND
)
2289 unshare_flags
|= CLONE_THREAD
;
2291 * If unsharing namespace, must also unshare filesystem information.
2293 if (unshare_flags
& CLONE_NEWNS
)
2294 unshare_flags
|= CLONE_FS
;
2296 err
= check_unshare_flags(unshare_flags
);
2298 goto bad_unshare_out
;
2300 * CLONE_NEWIPC must also detach from the undolist: after switching
2301 * to a new ipc namespace, the semaphore arrays from the old
2302 * namespace are unreachable.
2304 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2306 err
= unshare_fs(unshare_flags
, &new_fs
);
2308 goto bad_unshare_out
;
2309 err
= unshare_fd(unshare_flags
, &new_fd
);
2311 goto bad_unshare_cleanup_fs
;
2312 err
= unshare_userns(unshare_flags
, &new_cred
);
2314 goto bad_unshare_cleanup_fd
;
2315 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2318 goto bad_unshare_cleanup_cred
;
2320 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2323 * CLONE_SYSVSEM is equivalent to sys_exit().
2327 if (unshare_flags
& CLONE_NEWIPC
) {
2328 /* Orphan segments in old ns (see sem above). */
2330 shm_init_task(current
);
2334 switch_task_namespaces(current
, new_nsproxy
);
2340 spin_lock(&fs
->lock
);
2341 current
->fs
= new_fs
;
2346 spin_unlock(&fs
->lock
);
2350 fd
= current
->files
;
2351 current
->files
= new_fd
;
2355 task_unlock(current
);
2358 /* Install the new user namespace */
2359 commit_creds(new_cred
);
2364 perf_event_namespaces(current
);
2366 bad_unshare_cleanup_cred
:
2369 bad_unshare_cleanup_fd
:
2371 put_files_struct(new_fd
);
2373 bad_unshare_cleanup_fs
:
2375 free_fs_struct(new_fs
);
2382 * Helper to unshare the files of the current task.
2383 * We don't want to expose copy_files internals to
2384 * the exec layer of the kernel.
2387 int unshare_files(struct files_struct
**displaced
)
2389 struct task_struct
*task
= current
;
2390 struct files_struct
*copy
= NULL
;
2393 error
= unshare_fd(CLONE_FILES
, ©
);
2394 if (error
|| !copy
) {
2398 *displaced
= task
->files
;
2405 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2406 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2410 int threads
= max_threads
;
2411 int min
= MIN_THREADS
;
2412 int max
= MAX_THREADS
;
2419 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2423 set_max_threads(threads
);