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/init.h>
16 #include <linux/unistd.h>
17 #include <linux/module.h>
18 #include <linux/vmalloc.h>
19 #include <linux/completion.h>
20 #include <linux/personality.h>
21 #include <linux/mempolicy.h>
22 #include <linux/sem.h>
23 #include <linux/file.h>
24 #include <linux/fdtable.h>
25 #include <linux/iocontext.h>
26 #include <linux/key.h>
27 #include <linux/binfmts.h>
28 #include <linux/mman.h>
29 #include <linux/mmu_notifier.h>
32 #include <linux/vmacache.h>
33 #include <linux/nsproxy.h>
34 #include <linux/capability.h>
35 #include <linux/cpu.h>
36 #include <linux/cgroup.h>
37 #include <linux/security.h>
38 #include <linux/hugetlb.h>
39 #include <linux/seccomp.h>
40 #include <linux/swap.h>
41 #include <linux/syscalls.h>
42 #include <linux/jiffies.h>
43 #include <linux/futex.h>
44 #include <linux/compat.h>
45 #include <linux/kthread.h>
46 #include <linux/task_io_accounting_ops.h>
47 #include <linux/rcupdate.h>
48 #include <linux/ptrace.h>
49 #include <linux/mount.h>
50 #include <linux/audit.h>
51 #include <linux/memcontrol.h>
52 #include <linux/ftrace.h>
53 #include <linux/proc_fs.h>
54 #include <linux/profile.h>
55 #include <linux/rmap.h>
56 #include <linux/ksm.h>
57 #include <linux/acct.h>
58 #include <linux/userfaultfd_k.h>
59 #include <linux/tsacct_kern.h>
60 #include <linux/cn_proc.h>
61 #include <linux/freezer.h>
62 #include <linux/delayacct.h>
63 #include <linux/taskstats_kern.h>
64 #include <linux/random.h>
65 #include <linux/tty.h>
66 #include <linux/blkdev.h>
67 #include <linux/fs_struct.h>
68 #include <linux/magic.h>
69 #include <linux/perf_event.h>
70 #include <linux/posix-timers.h>
71 #include <linux/user-return-notifier.h>
72 #include <linux/oom.h>
73 #include <linux/khugepaged.h>
74 #include <linux/signalfd.h>
75 #include <linux/uprobes.h>
76 #include <linux/aio.h>
77 #include <linux/compiler.h>
78 #include <linux/sysctl.h>
79 #include <linux/kcov.h>
81 #include <asm/pgtable.h>
82 #include <asm/pgalloc.h>
83 #include <linux/uaccess.h>
84 #include <asm/mmu_context.h>
85 #include <asm/cacheflush.h>
86 #include <asm/tlbflush.h>
88 #include <trace/events/sched.h>
90 #define CREATE_TRACE_POINTS
91 #include <trace/events/task.h>
94 * Minimum number of threads to boot the kernel
96 #define MIN_THREADS 20
99 * Maximum number of threads
101 #define MAX_THREADS FUTEX_TID_MASK
104 * Protected counters by write_lock_irq(&tasklist_lock)
106 unsigned long total_forks
; /* Handle normal Linux uptimes. */
107 int nr_threads
; /* The idle threads do not count.. */
109 int max_threads
; /* tunable limit on nr_threads */
111 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
113 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
115 #ifdef CONFIG_PROVE_RCU
116 int lockdep_tasklist_lock_is_held(void)
118 return lockdep_is_held(&tasklist_lock
);
120 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
121 #endif /* #ifdef CONFIG_PROVE_RCU */
123 int nr_processes(void)
128 for_each_possible_cpu(cpu
)
129 total
+= per_cpu(process_counts
, cpu
);
134 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
138 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
139 static struct kmem_cache
*task_struct_cachep
;
141 static inline struct task_struct
*alloc_task_struct_node(int node
)
143 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
146 static inline void free_task_struct(struct task_struct
*tsk
)
148 kmem_cache_free(task_struct_cachep
, tsk
);
152 void __weak
arch_release_thread_stack(unsigned long *stack
)
156 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
159 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
160 * kmemcache based allocator.
162 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
164 #ifdef CONFIG_VMAP_STACK
166 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
167 * flush. Try to minimize the number of calls by caching stacks.
169 #define NR_CACHED_STACKS 2
170 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
173 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
175 #ifdef CONFIG_VMAP_STACK
180 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
181 struct vm_struct
*s
= this_cpu_read(cached_stacks
[i
]);
185 this_cpu_write(cached_stacks
[i
], NULL
);
187 tsk
->stack_vm_area
= s
;
193 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_SIZE
,
194 VMALLOC_START
, VMALLOC_END
,
195 THREADINFO_GFP
| __GFP_HIGHMEM
,
197 0, node
, __builtin_return_address(0));
200 * We can't call find_vm_area() in interrupt context, and
201 * free_thread_stack() can be called in interrupt context,
202 * so cache the vm_struct.
205 tsk
->stack_vm_area
= find_vm_area(stack
);
208 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
211 return page
? page_address(page
) : NULL
;
215 static inline void free_thread_stack(struct task_struct
*tsk
)
217 #ifdef CONFIG_VMAP_STACK
218 if (task_stack_vm_area(tsk
)) {
222 local_irq_save(flags
);
223 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
224 if (this_cpu_read(cached_stacks
[i
]))
227 this_cpu_write(cached_stacks
[i
], tsk
->stack_vm_area
);
228 local_irq_restore(flags
);
231 local_irq_restore(flags
);
233 vfree_atomic(tsk
->stack
);
238 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
241 static struct kmem_cache
*thread_stack_cache
;
243 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
246 return kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
249 static void free_thread_stack(struct task_struct
*tsk
)
251 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
254 void thread_stack_cache_init(void)
256 thread_stack_cache
= kmem_cache_create("thread_stack", THREAD_SIZE
,
257 THREAD_SIZE
, 0, NULL
);
258 BUG_ON(thread_stack_cache
== NULL
);
263 /* SLAB cache for signal_struct structures (tsk->signal) */
264 static struct kmem_cache
*signal_cachep
;
266 /* SLAB cache for sighand_struct structures (tsk->sighand) */
267 struct kmem_cache
*sighand_cachep
;
269 /* SLAB cache for files_struct structures (tsk->files) */
270 struct kmem_cache
*files_cachep
;
272 /* SLAB cache for fs_struct structures (tsk->fs) */
273 struct kmem_cache
*fs_cachep
;
275 /* SLAB cache for vm_area_struct structures */
276 struct kmem_cache
*vm_area_cachep
;
278 /* SLAB cache for mm_struct structures (tsk->mm) */
279 static struct kmem_cache
*mm_cachep
;
281 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
283 void *stack
= task_stack_page(tsk
);
284 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
286 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
291 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
293 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
294 mod_zone_page_state(page_zone(vm
->pages
[i
]),
296 PAGE_SIZE
/ 1024 * account
);
299 /* All stack pages belong to the same memcg. */
300 memcg_kmem_update_page_stat(vm
->pages
[0], MEMCG_KERNEL_STACK_KB
,
301 account
* (THREAD_SIZE
/ 1024));
304 * All stack pages are in the same zone and belong to the
307 struct page
*first_page
= virt_to_page(stack
);
309 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
310 THREAD_SIZE
/ 1024 * account
);
312 memcg_kmem_update_page_stat(first_page
, MEMCG_KERNEL_STACK_KB
,
313 account
* (THREAD_SIZE
/ 1024));
317 static void release_task_stack(struct task_struct
*tsk
)
319 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
320 return; /* Better to leak the stack than to free prematurely */
322 account_kernel_stack(tsk
, -1);
323 arch_release_thread_stack(tsk
->stack
);
324 free_thread_stack(tsk
);
326 #ifdef CONFIG_VMAP_STACK
327 tsk
->stack_vm_area
= NULL
;
331 #ifdef CONFIG_THREAD_INFO_IN_TASK
332 void put_task_stack(struct task_struct
*tsk
)
334 if (atomic_dec_and_test(&tsk
->stack_refcount
))
335 release_task_stack(tsk
);
339 void free_task(struct task_struct
*tsk
)
341 #ifndef CONFIG_THREAD_INFO_IN_TASK
343 * The task is finally done with both the stack and thread_info,
346 release_task_stack(tsk
);
349 * If the task had a separate stack allocation, it should be gone
352 WARN_ON_ONCE(atomic_read(&tsk
->stack_refcount
) != 0);
354 rt_mutex_debug_task_free(tsk
);
355 ftrace_graph_exit_task(tsk
);
356 put_seccomp_filter(tsk
);
357 arch_release_task_struct(tsk
);
358 if (tsk
->flags
& PF_KTHREAD
)
359 free_kthread_struct(tsk
);
360 free_task_struct(tsk
);
362 EXPORT_SYMBOL(free_task
);
364 static inline void free_signal_struct(struct signal_struct
*sig
)
366 taskstats_tgid_free(sig
);
367 sched_autogroup_exit(sig
);
369 * __mmdrop is not safe to call from softirq context on x86 due to
370 * pgd_dtor so postpone it to the async context
373 mmdrop_async(sig
->oom_mm
);
374 kmem_cache_free(signal_cachep
, sig
);
377 static inline void put_signal_struct(struct signal_struct
*sig
)
379 if (atomic_dec_and_test(&sig
->sigcnt
))
380 free_signal_struct(sig
);
383 void __put_task_struct(struct task_struct
*tsk
)
385 WARN_ON(!tsk
->exit_state
);
386 WARN_ON(atomic_read(&tsk
->usage
));
387 WARN_ON(tsk
== current
);
391 security_task_free(tsk
);
393 delayacct_tsk_free(tsk
);
394 put_signal_struct(tsk
->signal
);
396 if (!profile_handoff_task(tsk
))
399 EXPORT_SYMBOL_GPL(__put_task_struct
);
401 void __init __weak
arch_task_cache_init(void) { }
406 static void set_max_threads(unsigned int max_threads_suggested
)
411 * The number of threads shall be limited such that the thread
412 * structures may only consume a small part of the available memory.
414 if (fls64(totalram_pages
) + fls64(PAGE_SIZE
) > 64)
415 threads
= MAX_THREADS
;
417 threads
= div64_u64((u64
) totalram_pages
* (u64
) PAGE_SIZE
,
418 (u64
) THREAD_SIZE
* 8UL);
420 if (threads
> max_threads_suggested
)
421 threads
= max_threads_suggested
;
423 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
426 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
427 /* Initialized by the architecture: */
428 int arch_task_struct_size __read_mostly
;
431 void __init
fork_init(void)
434 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
435 #ifndef ARCH_MIN_TASKALIGN
436 #define ARCH_MIN_TASKALIGN 0
438 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
440 /* create a slab on which task_structs can be allocated */
441 task_struct_cachep
= kmem_cache_create("task_struct",
442 arch_task_struct_size
, align
,
443 SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
, NULL
);
446 /* do the arch specific task caches init */
447 arch_task_cache_init();
449 set_max_threads(MAX_THREADS
);
451 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
452 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
453 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
454 init_task
.signal
->rlim
[RLIMIT_NPROC
];
456 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
457 init_user_ns
.ucount_max
[i
] = max_threads
/2;
461 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
462 struct task_struct
*src
)
468 void set_task_stack_end_magic(struct task_struct
*tsk
)
470 unsigned long *stackend
;
472 stackend
= end_of_stack(tsk
);
473 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
476 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
478 struct task_struct
*tsk
;
479 unsigned long *stack
;
480 struct vm_struct
*stack_vm_area
;
483 if (node
== NUMA_NO_NODE
)
484 node
= tsk_fork_get_node(orig
);
485 tsk
= alloc_task_struct_node(node
);
489 stack
= alloc_thread_stack_node(tsk
, node
);
493 stack_vm_area
= task_stack_vm_area(tsk
);
495 err
= arch_dup_task_struct(tsk
, orig
);
498 * arch_dup_task_struct() clobbers the stack-related fields. Make
499 * sure they're properly initialized before using any stack-related
503 #ifdef CONFIG_VMAP_STACK
504 tsk
->stack_vm_area
= stack_vm_area
;
506 #ifdef CONFIG_THREAD_INFO_IN_TASK
507 atomic_set(&tsk
->stack_refcount
, 1);
513 #ifdef CONFIG_SECCOMP
515 * We must handle setting up seccomp filters once we're under
516 * the sighand lock in case orig has changed between now and
517 * then. Until then, filter must be NULL to avoid messing up
518 * the usage counts on the error path calling free_task.
520 tsk
->seccomp
.filter
= NULL
;
523 setup_thread_stack(tsk
, orig
);
524 clear_user_return_notifier(tsk
);
525 clear_tsk_need_resched(tsk
);
526 set_task_stack_end_magic(tsk
);
528 #ifdef CONFIG_CC_STACKPROTECTOR
529 tsk
->stack_canary
= get_random_int();
533 * One for us, one for whoever does the "release_task()" (usually
536 atomic_set(&tsk
->usage
, 2);
537 #ifdef CONFIG_BLK_DEV_IO_TRACE
540 tsk
->splice_pipe
= NULL
;
541 tsk
->task_frag
.page
= NULL
;
542 tsk
->wake_q
.next
= NULL
;
544 account_kernel_stack(tsk
, 1);
551 free_thread_stack(tsk
);
553 free_task_struct(tsk
);
558 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
559 struct mm_struct
*oldmm
)
561 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
562 struct rb_node
**rb_link
, *rb_parent
;
564 unsigned long charge
;
567 uprobe_start_dup_mmap();
568 if (down_write_killable(&oldmm
->mmap_sem
)) {
570 goto fail_uprobe_end
;
572 flush_cache_dup_mm(oldmm
);
573 uprobe_dup_mmap(oldmm
, mm
);
575 * Not linked in yet - no deadlock potential:
577 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
579 /* No ordering required: file already has been exposed. */
580 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
582 mm
->total_vm
= oldmm
->total_vm
;
583 mm
->data_vm
= oldmm
->data_vm
;
584 mm
->exec_vm
= oldmm
->exec_vm
;
585 mm
->stack_vm
= oldmm
->stack_vm
;
587 rb_link
= &mm
->mm_rb
.rb_node
;
590 retval
= ksm_fork(mm
, oldmm
);
593 retval
= khugepaged_fork(mm
, oldmm
);
598 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
601 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
602 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
606 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
607 unsigned long len
= vma_pages(mpnt
);
609 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
613 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
617 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
618 retval
= vma_dup_policy(mpnt
, tmp
);
620 goto fail_nomem_policy
;
622 retval
= dup_userfaultfd(tmp
, &uf
);
624 goto fail_nomem_anon_vma_fork
;
625 if (anon_vma_fork(tmp
, mpnt
))
626 goto fail_nomem_anon_vma_fork
;
627 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
628 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
631 struct inode
*inode
= file_inode(file
);
632 struct address_space
*mapping
= file
->f_mapping
;
635 if (tmp
->vm_flags
& VM_DENYWRITE
)
636 atomic_dec(&inode
->i_writecount
);
637 i_mmap_lock_write(mapping
);
638 if (tmp
->vm_flags
& VM_SHARED
)
639 atomic_inc(&mapping
->i_mmap_writable
);
640 flush_dcache_mmap_lock(mapping
);
641 /* insert tmp into the share list, just after mpnt */
642 vma_interval_tree_insert_after(tmp
, mpnt
,
644 flush_dcache_mmap_unlock(mapping
);
645 i_mmap_unlock_write(mapping
);
649 * Clear hugetlb-related page reserves for children. This only
650 * affects MAP_PRIVATE mappings. Faults generated by the child
651 * are not guaranteed to succeed, even if read-only
653 if (is_vm_hugetlb_page(tmp
))
654 reset_vma_resv_huge_pages(tmp
);
657 * Link in the new vma and copy the page table entries.
660 pprev
= &tmp
->vm_next
;
664 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
665 rb_link
= &tmp
->vm_rb
.rb_right
;
666 rb_parent
= &tmp
->vm_rb
;
669 retval
= copy_page_range(mm
, oldmm
, mpnt
);
671 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
672 tmp
->vm_ops
->open(tmp
);
677 /* a new mm has just been created */
678 arch_dup_mmap(oldmm
, mm
);
681 up_write(&mm
->mmap_sem
);
683 up_write(&oldmm
->mmap_sem
);
684 dup_userfaultfd_complete(&uf
);
686 uprobe_end_dup_mmap();
688 fail_nomem_anon_vma_fork
:
689 mpol_put(vma_policy(tmp
));
691 kmem_cache_free(vm_area_cachep
, tmp
);
694 vm_unacct_memory(charge
);
698 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
700 mm
->pgd
= pgd_alloc(mm
);
701 if (unlikely(!mm
->pgd
))
706 static inline void mm_free_pgd(struct mm_struct
*mm
)
708 pgd_free(mm
, mm
->pgd
);
711 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
713 down_write(&oldmm
->mmap_sem
);
714 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
715 up_write(&oldmm
->mmap_sem
);
718 #define mm_alloc_pgd(mm) (0)
719 #define mm_free_pgd(mm)
720 #endif /* CONFIG_MMU */
722 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
724 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
725 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
727 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
729 static int __init
coredump_filter_setup(char *s
)
731 default_dump_filter
=
732 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
733 MMF_DUMP_FILTER_MASK
;
737 __setup("coredump_filter=", coredump_filter_setup
);
739 #include <linux/init_task.h>
741 static void mm_init_aio(struct mm_struct
*mm
)
744 spin_lock_init(&mm
->ioctx_lock
);
745 mm
->ioctx_table
= NULL
;
749 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
756 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
757 struct user_namespace
*user_ns
)
761 mm
->vmacache_seqnum
= 0;
762 atomic_set(&mm
->mm_users
, 1);
763 atomic_set(&mm
->mm_count
, 1);
764 init_rwsem(&mm
->mmap_sem
);
765 INIT_LIST_HEAD(&mm
->mmlist
);
766 mm
->core_state
= NULL
;
767 atomic_long_set(&mm
->nr_ptes
, 0);
772 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
773 spin_lock_init(&mm
->page_table_lock
);
776 mm_init_owner(mm
, p
);
777 mmu_notifier_mm_init(mm
);
778 clear_tlb_flush_pending(mm
);
779 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
780 mm
->pmd_huge_pte
= NULL
;
784 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
785 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
787 mm
->flags
= default_dump_filter
;
791 if (mm_alloc_pgd(mm
))
794 if (init_new_context(p
, mm
))
797 mm
->user_ns
= get_user_ns(user_ns
);
807 static void check_mm(struct mm_struct
*mm
)
811 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
812 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
815 printk(KERN_ALERT
"BUG: Bad rss-counter state "
816 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
819 if (atomic_long_read(&mm
->nr_ptes
))
820 pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
821 atomic_long_read(&mm
->nr_ptes
));
823 pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
826 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
827 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
832 * Allocate and initialize an mm_struct.
834 struct mm_struct
*mm_alloc(void)
836 struct mm_struct
*mm
;
842 memset(mm
, 0, sizeof(*mm
));
843 return mm_init(mm
, current
, current_user_ns());
847 * Called when the last reference to the mm
848 * is dropped: either by a lazy thread or by
849 * mmput. Free the page directory and the mm.
851 void __mmdrop(struct mm_struct
*mm
)
853 BUG_ON(mm
== &init_mm
);
856 mmu_notifier_mm_destroy(mm
);
858 put_user_ns(mm
->user_ns
);
861 EXPORT_SYMBOL_GPL(__mmdrop
);
863 static inline void __mmput(struct mm_struct
*mm
)
865 VM_BUG_ON(atomic_read(&mm
->mm_users
));
867 uprobe_clear_state(mm
);
870 khugepaged_exit(mm
); /* must run before exit_mmap */
872 mm_put_huge_zero_page(mm
);
873 set_mm_exe_file(mm
, NULL
);
874 if (!list_empty(&mm
->mmlist
)) {
875 spin_lock(&mmlist_lock
);
876 list_del(&mm
->mmlist
);
877 spin_unlock(&mmlist_lock
);
880 module_put(mm
->binfmt
->module
);
881 set_bit(MMF_OOM_SKIP
, &mm
->flags
);
886 * Decrement the use count and release all resources for an mm.
888 void mmput(struct mm_struct
*mm
)
892 if (atomic_dec_and_test(&mm
->mm_users
))
895 EXPORT_SYMBOL_GPL(mmput
);
898 static void mmput_async_fn(struct work_struct
*work
)
900 struct mm_struct
*mm
= container_of(work
, struct mm_struct
, async_put_work
);
904 void mmput_async(struct mm_struct
*mm
)
906 if (atomic_dec_and_test(&mm
->mm_users
)) {
907 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
908 schedule_work(&mm
->async_put_work
);
914 * set_mm_exe_file - change a reference to the mm's executable file
916 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
918 * Main users are mmput() and sys_execve(). Callers prevent concurrent
919 * invocations: in mmput() nobody alive left, in execve task is single
920 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
921 * mm->exe_file, but does so without using set_mm_exe_file() in order
922 * to do avoid the need for any locks.
924 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
926 struct file
*old_exe_file
;
929 * It is safe to dereference the exe_file without RCU as
930 * this function is only called if nobody else can access
931 * this mm -- see comment above for justification.
933 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
936 get_file(new_exe_file
);
937 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
943 * get_mm_exe_file - acquire a reference to the mm's executable file
945 * Returns %NULL if mm has no associated executable file.
946 * User must release file via fput().
948 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
950 struct file
*exe_file
;
953 exe_file
= rcu_dereference(mm
->exe_file
);
954 if (exe_file
&& !get_file_rcu(exe_file
))
959 EXPORT_SYMBOL(get_mm_exe_file
);
962 * get_task_exe_file - acquire a reference to the task's executable file
964 * Returns %NULL if task's mm (if any) has no associated executable file or
965 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
966 * User must release file via fput().
968 struct file
*get_task_exe_file(struct task_struct
*task
)
970 struct file
*exe_file
= NULL
;
971 struct mm_struct
*mm
;
976 if (!(task
->flags
& PF_KTHREAD
))
977 exe_file
= get_mm_exe_file(mm
);
982 EXPORT_SYMBOL(get_task_exe_file
);
985 * get_task_mm - acquire a reference to the task's mm
987 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
988 * this kernel workthread has transiently adopted a user mm with use_mm,
989 * to do its AIO) is not set and if so returns a reference to it, after
990 * bumping up the use count. User must release the mm via mmput()
991 * after use. Typically used by /proc and ptrace.
993 struct mm_struct
*get_task_mm(struct task_struct
*task
)
995 struct mm_struct
*mm
;
1000 if (task
->flags
& PF_KTHREAD
)
1008 EXPORT_SYMBOL_GPL(get_task_mm
);
1010 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1012 struct mm_struct
*mm
;
1015 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
1017 return ERR_PTR(err
);
1019 mm
= get_task_mm(task
);
1020 if (mm
&& mm
!= current
->mm
&&
1021 !ptrace_may_access(task
, mode
)) {
1023 mm
= ERR_PTR(-EACCES
);
1025 mutex_unlock(&task
->signal
->cred_guard_mutex
);
1030 static void complete_vfork_done(struct task_struct
*tsk
)
1032 struct completion
*vfork
;
1035 vfork
= tsk
->vfork_done
;
1036 if (likely(vfork
)) {
1037 tsk
->vfork_done
= NULL
;
1043 static int wait_for_vfork_done(struct task_struct
*child
,
1044 struct completion
*vfork
)
1048 freezer_do_not_count();
1049 killed
= wait_for_completion_killable(vfork
);
1054 child
->vfork_done
= NULL
;
1058 put_task_struct(child
);
1062 /* Please note the differences between mmput and mm_release.
1063 * mmput is called whenever we stop holding onto a mm_struct,
1064 * error success whatever.
1066 * mm_release is called after a mm_struct has been removed
1067 * from the current process.
1069 * This difference is important for error handling, when we
1070 * only half set up a mm_struct for a new process and need to restore
1071 * the old one. Because we mmput the new mm_struct before
1072 * restoring the old one. . .
1073 * Eric Biederman 10 January 1998
1075 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1077 /* Get rid of any futexes when releasing the mm */
1079 if (unlikely(tsk
->robust_list
)) {
1080 exit_robust_list(tsk
);
1081 tsk
->robust_list
= NULL
;
1083 #ifdef CONFIG_COMPAT
1084 if (unlikely(tsk
->compat_robust_list
)) {
1085 compat_exit_robust_list(tsk
);
1086 tsk
->compat_robust_list
= NULL
;
1089 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1090 exit_pi_state_list(tsk
);
1093 uprobe_free_utask(tsk
);
1095 /* Get rid of any cached register state */
1096 deactivate_mm(tsk
, mm
);
1099 * Signal userspace if we're not exiting with a core dump
1100 * because we want to leave the value intact for debugging
1103 if (tsk
->clear_child_tid
) {
1104 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1105 atomic_read(&mm
->mm_users
) > 1) {
1107 * We don't check the error code - if userspace has
1108 * not set up a proper pointer then tough luck.
1110 put_user(0, tsk
->clear_child_tid
);
1111 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1114 tsk
->clear_child_tid
= NULL
;
1118 * All done, finally we can wake up parent and return this mm to him.
1119 * Also kthread_stop() uses this completion for synchronization.
1121 if (tsk
->vfork_done
)
1122 complete_vfork_done(tsk
);
1126 * Allocate a new mm structure and copy contents from the
1127 * mm structure of the passed in task structure.
1129 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
1131 struct mm_struct
*mm
, *oldmm
= current
->mm
;
1138 memcpy(mm
, oldmm
, sizeof(*mm
));
1140 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1143 err
= dup_mmap(mm
, oldmm
);
1147 mm
->hiwater_rss
= get_mm_rss(mm
);
1148 mm
->hiwater_vm
= mm
->total_vm
;
1150 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1156 /* don't put binfmt in mmput, we haven't got module yet */
1164 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1166 struct mm_struct
*mm
, *oldmm
;
1169 tsk
->min_flt
= tsk
->maj_flt
= 0;
1170 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1171 #ifdef CONFIG_DETECT_HUNG_TASK
1172 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1176 tsk
->active_mm
= NULL
;
1179 * Are we cloning a kernel thread?
1181 * We need to steal a active VM for that..
1183 oldmm
= current
->mm
;
1187 /* initialize the new vmacache entries */
1188 vmacache_flush(tsk
);
1190 if (clone_flags
& CLONE_VM
) {
1203 tsk
->active_mm
= mm
;
1210 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1212 struct fs_struct
*fs
= current
->fs
;
1213 if (clone_flags
& CLONE_FS
) {
1214 /* tsk->fs is already what we want */
1215 spin_lock(&fs
->lock
);
1217 spin_unlock(&fs
->lock
);
1221 spin_unlock(&fs
->lock
);
1224 tsk
->fs
= copy_fs_struct(fs
);
1230 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1232 struct files_struct
*oldf
, *newf
;
1236 * A background process may not have any files ...
1238 oldf
= current
->files
;
1242 if (clone_flags
& CLONE_FILES
) {
1243 atomic_inc(&oldf
->count
);
1247 newf
= dup_fd(oldf
, &error
);
1257 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1260 struct io_context
*ioc
= current
->io_context
;
1261 struct io_context
*new_ioc
;
1266 * Share io context with parent, if CLONE_IO is set
1268 if (clone_flags
& CLONE_IO
) {
1270 tsk
->io_context
= ioc
;
1271 } else if (ioprio_valid(ioc
->ioprio
)) {
1272 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1273 if (unlikely(!new_ioc
))
1276 new_ioc
->ioprio
= ioc
->ioprio
;
1277 put_io_context(new_ioc
);
1283 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1285 struct sighand_struct
*sig
;
1287 if (clone_flags
& CLONE_SIGHAND
) {
1288 atomic_inc(¤t
->sighand
->count
);
1291 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1292 rcu_assign_pointer(tsk
->sighand
, sig
);
1296 atomic_set(&sig
->count
, 1);
1297 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1301 void __cleanup_sighand(struct sighand_struct
*sighand
)
1303 if (atomic_dec_and_test(&sighand
->count
)) {
1304 signalfd_cleanup(sighand
);
1306 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
1307 * without an RCU grace period, see __lock_task_sighand().
1309 kmem_cache_free(sighand_cachep
, sighand
);
1313 #ifdef CONFIG_POSIX_TIMERS
1315 * Initialize POSIX timer handling for a thread group.
1317 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1319 unsigned long cpu_limit
;
1321 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1322 if (cpu_limit
!= RLIM_INFINITY
) {
1323 sig
->cputime_expires
.prof_exp
= cpu_limit
* NSEC_PER_SEC
;
1324 sig
->cputimer
.running
= true;
1327 /* The timer lists. */
1328 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1329 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1330 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1333 static inline void posix_cpu_timers_init_group(struct signal_struct
*sig
) { }
1336 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1338 struct signal_struct
*sig
;
1340 if (clone_flags
& CLONE_THREAD
)
1343 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1348 sig
->nr_threads
= 1;
1349 atomic_set(&sig
->live
, 1);
1350 atomic_set(&sig
->sigcnt
, 1);
1352 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1353 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1354 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1356 init_waitqueue_head(&sig
->wait_chldexit
);
1357 sig
->curr_target
= tsk
;
1358 init_sigpending(&sig
->shared_pending
);
1359 seqlock_init(&sig
->stats_lock
);
1360 prev_cputime_init(&sig
->prev_cputime
);
1362 #ifdef CONFIG_POSIX_TIMERS
1363 INIT_LIST_HEAD(&sig
->posix_timers
);
1364 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1365 sig
->real_timer
.function
= it_real_fn
;
1368 task_lock(current
->group_leader
);
1369 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1370 task_unlock(current
->group_leader
);
1372 posix_cpu_timers_init_group(sig
);
1374 tty_audit_fork(sig
);
1375 sched_autogroup_fork(sig
);
1377 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1378 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1380 mutex_init(&sig
->cred_guard_mutex
);
1385 static void copy_seccomp(struct task_struct
*p
)
1387 #ifdef CONFIG_SECCOMP
1389 * Must be called with sighand->lock held, which is common to
1390 * all threads in the group. Holding cred_guard_mutex is not
1391 * needed because this new task is not yet running and cannot
1394 assert_spin_locked(¤t
->sighand
->siglock
);
1396 /* Ref-count the new filter user, and assign it. */
1397 get_seccomp_filter(current
);
1398 p
->seccomp
= current
->seccomp
;
1401 * Explicitly enable no_new_privs here in case it got set
1402 * between the task_struct being duplicated and holding the
1403 * sighand lock. The seccomp state and nnp must be in sync.
1405 if (task_no_new_privs(current
))
1406 task_set_no_new_privs(p
);
1409 * If the parent gained a seccomp mode after copying thread
1410 * flags and between before we held the sighand lock, we have
1411 * to manually enable the seccomp thread flag here.
1413 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1414 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1418 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1420 current
->clear_child_tid
= tidptr
;
1422 return task_pid_vnr(current
);
1425 static void rt_mutex_init_task(struct task_struct
*p
)
1427 raw_spin_lock_init(&p
->pi_lock
);
1428 #ifdef CONFIG_RT_MUTEXES
1429 p
->pi_waiters
= RB_ROOT
;
1430 p
->pi_waiters_leftmost
= NULL
;
1431 p
->pi_blocked_on
= NULL
;
1435 #ifdef CONFIG_POSIX_TIMERS
1437 * Initialize POSIX timer handling for a single task.
1439 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1441 tsk
->cputime_expires
.prof_exp
= 0;
1442 tsk
->cputime_expires
.virt_exp
= 0;
1443 tsk
->cputime_expires
.sched_exp
= 0;
1444 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1445 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1446 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1449 static inline void posix_cpu_timers_init(struct task_struct
*tsk
) { }
1453 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1455 task
->pids
[type
].pid
= pid
;
1459 * This creates a new process as a copy of the old one,
1460 * but does not actually start it yet.
1462 * It copies the registers, and all the appropriate
1463 * parts of the process environment (as per the clone
1464 * flags). The actual kick-off is left to the caller.
1466 static __latent_entropy
struct task_struct
*copy_process(
1467 unsigned long clone_flags
,
1468 unsigned long stack_start
,
1469 unsigned long stack_size
,
1470 int __user
*child_tidptr
,
1477 struct task_struct
*p
;
1479 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1480 return ERR_PTR(-EINVAL
);
1482 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1483 return ERR_PTR(-EINVAL
);
1486 * Thread groups must share signals as well, and detached threads
1487 * can only be started up within the thread group.
1489 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1490 return ERR_PTR(-EINVAL
);
1493 * Shared signal handlers imply shared VM. By way of the above,
1494 * thread groups also imply shared VM. Blocking this case allows
1495 * for various simplifications in other code.
1497 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1498 return ERR_PTR(-EINVAL
);
1501 * Siblings of global init remain as zombies on exit since they are
1502 * not reaped by their parent (swapper). To solve this and to avoid
1503 * multi-rooted process trees, prevent global and container-inits
1504 * from creating siblings.
1506 if ((clone_flags
& CLONE_PARENT
) &&
1507 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1508 return ERR_PTR(-EINVAL
);
1511 * If the new process will be in a different pid or user namespace
1512 * do not allow it to share a thread group with the forking task.
1514 if (clone_flags
& CLONE_THREAD
) {
1515 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1516 (task_active_pid_ns(current
) !=
1517 current
->nsproxy
->pid_ns_for_children
))
1518 return ERR_PTR(-EINVAL
);
1521 retval
= security_task_create(clone_flags
);
1526 p
= dup_task_struct(current
, node
);
1530 ftrace_graph_init_task(p
);
1532 rt_mutex_init_task(p
);
1534 #ifdef CONFIG_PROVE_LOCKING
1535 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1536 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1539 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1540 task_rlimit(p
, RLIMIT_NPROC
)) {
1541 if (p
->real_cred
->user
!= INIT_USER
&&
1542 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1545 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1547 retval
= copy_creds(p
, clone_flags
);
1552 * If multiple threads are within copy_process(), then this check
1553 * triggers too late. This doesn't hurt, the check is only there
1554 * to stop root fork bombs.
1557 if (nr_threads
>= max_threads
)
1558 goto bad_fork_cleanup_count
;
1560 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1561 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1562 p
->flags
|= PF_FORKNOEXEC
;
1563 INIT_LIST_HEAD(&p
->children
);
1564 INIT_LIST_HEAD(&p
->sibling
);
1565 rcu_copy_process(p
);
1566 p
->vfork_done
= NULL
;
1567 spin_lock_init(&p
->alloc_lock
);
1569 init_sigpending(&p
->pending
);
1571 p
->utime
= p
->stime
= p
->gtime
= 0;
1572 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1573 p
->utimescaled
= p
->stimescaled
= 0;
1575 prev_cputime_init(&p
->prev_cputime
);
1577 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1578 seqcount_init(&p
->vtime_seqcount
);
1580 p
->vtime_snap_whence
= VTIME_INACTIVE
;
1583 #if defined(SPLIT_RSS_COUNTING)
1584 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1587 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1589 task_io_accounting_init(&p
->ioac
);
1590 acct_clear_integrals(p
);
1592 posix_cpu_timers_init(p
);
1594 p
->start_time
= ktime_get_ns();
1595 p
->real_start_time
= ktime_get_boot_ns();
1596 p
->io_context
= NULL
;
1597 p
->audit_context
= NULL
;
1600 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1601 if (IS_ERR(p
->mempolicy
)) {
1602 retval
= PTR_ERR(p
->mempolicy
);
1603 p
->mempolicy
= NULL
;
1604 goto bad_fork_cleanup_threadgroup_lock
;
1607 #ifdef CONFIG_CPUSETS
1608 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1609 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1610 seqcount_init(&p
->mems_allowed_seq
);
1612 #ifdef CONFIG_TRACE_IRQFLAGS
1614 p
->hardirqs_enabled
= 0;
1615 p
->hardirq_enable_ip
= 0;
1616 p
->hardirq_enable_event
= 0;
1617 p
->hardirq_disable_ip
= _THIS_IP_
;
1618 p
->hardirq_disable_event
= 0;
1619 p
->softirqs_enabled
= 1;
1620 p
->softirq_enable_ip
= _THIS_IP_
;
1621 p
->softirq_enable_event
= 0;
1622 p
->softirq_disable_ip
= 0;
1623 p
->softirq_disable_event
= 0;
1624 p
->hardirq_context
= 0;
1625 p
->softirq_context
= 0;
1628 p
->pagefault_disabled
= 0;
1630 #ifdef CONFIG_LOCKDEP
1631 p
->lockdep_depth
= 0; /* no locks held yet */
1632 p
->curr_chain_key
= 0;
1633 p
->lockdep_recursion
= 0;
1636 #ifdef CONFIG_DEBUG_MUTEXES
1637 p
->blocked_on
= NULL
; /* not blocked yet */
1639 #ifdef CONFIG_BCACHE
1640 p
->sequential_io
= 0;
1641 p
->sequential_io_avg
= 0;
1644 /* Perform scheduler related setup. Assign this task to a CPU. */
1645 retval
= sched_fork(clone_flags
, p
);
1647 goto bad_fork_cleanup_policy
;
1649 retval
= perf_event_init_task(p
);
1651 goto bad_fork_cleanup_policy
;
1652 retval
= audit_alloc(p
);
1654 goto bad_fork_cleanup_perf
;
1655 /* copy all the process information */
1657 retval
= copy_semundo(clone_flags
, p
);
1659 goto bad_fork_cleanup_audit
;
1660 retval
= copy_files(clone_flags
, p
);
1662 goto bad_fork_cleanup_semundo
;
1663 retval
= copy_fs(clone_flags
, p
);
1665 goto bad_fork_cleanup_files
;
1666 retval
= copy_sighand(clone_flags
, p
);
1668 goto bad_fork_cleanup_fs
;
1669 retval
= copy_signal(clone_flags
, p
);
1671 goto bad_fork_cleanup_sighand
;
1672 retval
= copy_mm(clone_flags
, p
);
1674 goto bad_fork_cleanup_signal
;
1675 retval
= copy_namespaces(clone_flags
, p
);
1677 goto bad_fork_cleanup_mm
;
1678 retval
= copy_io(clone_flags
, p
);
1680 goto bad_fork_cleanup_namespaces
;
1681 retval
= copy_thread_tls(clone_flags
, stack_start
, stack_size
, p
, tls
);
1683 goto bad_fork_cleanup_io
;
1685 if (pid
!= &init_struct_pid
) {
1686 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1688 retval
= PTR_ERR(pid
);
1689 goto bad_fork_cleanup_thread
;
1693 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1695 * Clear TID on mm_release()?
1697 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1702 p
->robust_list
= NULL
;
1703 #ifdef CONFIG_COMPAT
1704 p
->compat_robust_list
= NULL
;
1706 INIT_LIST_HEAD(&p
->pi_state_list
);
1707 p
->pi_state_cache
= NULL
;
1710 * sigaltstack should be cleared when sharing the same VM
1712 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1716 * Syscall tracing and stepping should be turned off in the
1717 * child regardless of CLONE_PTRACE.
1719 user_disable_single_step(p
);
1720 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1721 #ifdef TIF_SYSCALL_EMU
1722 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1724 clear_all_latency_tracing(p
);
1726 /* ok, now we should be set up.. */
1727 p
->pid
= pid_nr(pid
);
1728 if (clone_flags
& CLONE_THREAD
) {
1729 p
->exit_signal
= -1;
1730 p
->group_leader
= current
->group_leader
;
1731 p
->tgid
= current
->tgid
;
1733 if (clone_flags
& CLONE_PARENT
)
1734 p
->exit_signal
= current
->group_leader
->exit_signal
;
1736 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1737 p
->group_leader
= p
;
1742 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1743 p
->dirty_paused_when
= 0;
1745 p
->pdeath_signal
= 0;
1746 INIT_LIST_HEAD(&p
->thread_group
);
1747 p
->task_works
= NULL
;
1749 threadgroup_change_begin(current
);
1751 * Ensure that the cgroup subsystem policies allow the new process to be
1752 * forked. It should be noted the the new process's css_set can be changed
1753 * between here and cgroup_post_fork() if an organisation operation is in
1756 retval
= cgroup_can_fork(p
);
1758 goto bad_fork_free_pid
;
1761 * Make it visible to the rest of the system, but dont wake it up yet.
1762 * Need tasklist lock for parent etc handling!
1764 write_lock_irq(&tasklist_lock
);
1766 /* CLONE_PARENT re-uses the old parent */
1767 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1768 p
->real_parent
= current
->real_parent
;
1769 p
->parent_exec_id
= current
->parent_exec_id
;
1771 p
->real_parent
= current
;
1772 p
->parent_exec_id
= current
->self_exec_id
;
1775 spin_lock(¤t
->sighand
->siglock
);
1778 * Copy seccomp details explicitly here, in case they were changed
1779 * before holding sighand lock.
1784 * Process group and session signals need to be delivered to just the
1785 * parent before the fork or both the parent and the child after the
1786 * fork. Restart if a signal comes in before we add the new process to
1787 * it's process group.
1788 * A fatal signal pending means that current will exit, so the new
1789 * thread can't slip out of an OOM kill (or normal SIGKILL).
1791 recalc_sigpending();
1792 if (signal_pending(current
)) {
1793 spin_unlock(¤t
->sighand
->siglock
);
1794 write_unlock_irq(&tasklist_lock
);
1795 retval
= -ERESTARTNOINTR
;
1796 goto bad_fork_cancel_cgroup
;
1799 if (likely(p
->pid
)) {
1800 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1802 init_task_pid(p
, PIDTYPE_PID
, pid
);
1803 if (thread_group_leader(p
)) {
1804 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1805 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1807 if (is_child_reaper(pid
)) {
1808 ns_of_pid(pid
)->child_reaper
= p
;
1809 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1812 p
->signal
->leader_pid
= pid
;
1813 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1815 * Inherit has_child_subreaper flag under the same
1816 * tasklist_lock with adding child to the process tree
1817 * for propagate_has_child_subreaper optimization.
1819 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
1820 p
->real_parent
->signal
->is_child_subreaper
;
1821 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1822 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1823 attach_pid(p
, PIDTYPE_PGID
);
1824 attach_pid(p
, PIDTYPE_SID
);
1825 __this_cpu_inc(process_counts
);
1827 current
->signal
->nr_threads
++;
1828 atomic_inc(¤t
->signal
->live
);
1829 atomic_inc(¤t
->signal
->sigcnt
);
1830 list_add_tail_rcu(&p
->thread_group
,
1831 &p
->group_leader
->thread_group
);
1832 list_add_tail_rcu(&p
->thread_node
,
1833 &p
->signal
->thread_head
);
1835 attach_pid(p
, PIDTYPE_PID
);
1840 spin_unlock(¤t
->sighand
->siglock
);
1841 syscall_tracepoint_update(p
);
1842 write_unlock_irq(&tasklist_lock
);
1844 proc_fork_connector(p
);
1845 cgroup_post_fork(p
);
1846 threadgroup_change_end(current
);
1849 trace_task_newtask(p
, clone_flags
);
1850 uprobe_copy_process(p
, clone_flags
);
1854 bad_fork_cancel_cgroup
:
1855 cgroup_cancel_fork(p
);
1857 threadgroup_change_end(current
);
1858 if (pid
!= &init_struct_pid
)
1860 bad_fork_cleanup_thread
:
1862 bad_fork_cleanup_io
:
1865 bad_fork_cleanup_namespaces
:
1866 exit_task_namespaces(p
);
1867 bad_fork_cleanup_mm
:
1870 bad_fork_cleanup_signal
:
1871 if (!(clone_flags
& CLONE_THREAD
))
1872 free_signal_struct(p
->signal
);
1873 bad_fork_cleanup_sighand
:
1874 __cleanup_sighand(p
->sighand
);
1875 bad_fork_cleanup_fs
:
1876 exit_fs(p
); /* blocking */
1877 bad_fork_cleanup_files
:
1878 exit_files(p
); /* blocking */
1879 bad_fork_cleanup_semundo
:
1881 bad_fork_cleanup_audit
:
1883 bad_fork_cleanup_perf
:
1884 perf_event_free_task(p
);
1885 bad_fork_cleanup_policy
:
1887 mpol_put(p
->mempolicy
);
1888 bad_fork_cleanup_threadgroup_lock
:
1890 delayacct_tsk_free(p
);
1891 bad_fork_cleanup_count
:
1892 atomic_dec(&p
->cred
->user
->processes
);
1895 p
->state
= TASK_DEAD
;
1899 return ERR_PTR(retval
);
1902 static inline void init_idle_pids(struct pid_link
*links
)
1906 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1907 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1908 links
[type
].pid
= &init_struct_pid
;
1912 struct task_struct
*fork_idle(int cpu
)
1914 struct task_struct
*task
;
1915 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0, 0,
1917 if (!IS_ERR(task
)) {
1918 init_idle_pids(task
->pids
);
1919 init_idle(task
, cpu
);
1926 * Ok, this is the main fork-routine.
1928 * It copies the process, and if successful kick-starts
1929 * it and waits for it to finish using the VM if required.
1931 long _do_fork(unsigned long clone_flags
,
1932 unsigned long stack_start
,
1933 unsigned long stack_size
,
1934 int __user
*parent_tidptr
,
1935 int __user
*child_tidptr
,
1938 struct task_struct
*p
;
1943 * Determine whether and which event to report to ptracer. When
1944 * called from kernel_thread or CLONE_UNTRACED is explicitly
1945 * requested, no event is reported; otherwise, report if the event
1946 * for the type of forking is enabled.
1948 if (!(clone_flags
& CLONE_UNTRACED
)) {
1949 if (clone_flags
& CLONE_VFORK
)
1950 trace
= PTRACE_EVENT_VFORK
;
1951 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1952 trace
= PTRACE_EVENT_CLONE
;
1954 trace
= PTRACE_EVENT_FORK
;
1956 if (likely(!ptrace_event_enabled(current
, trace
)))
1960 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1961 child_tidptr
, NULL
, trace
, tls
, NUMA_NO_NODE
);
1962 add_latent_entropy();
1964 * Do this prior waking up the new thread - the thread pointer
1965 * might get invalid after that point, if the thread exits quickly.
1968 struct completion vfork
;
1971 trace_sched_process_fork(current
, p
);
1973 pid
= get_task_pid(p
, PIDTYPE_PID
);
1976 if (clone_flags
& CLONE_PARENT_SETTID
)
1977 put_user(nr
, parent_tidptr
);
1979 if (clone_flags
& CLONE_VFORK
) {
1980 p
->vfork_done
= &vfork
;
1981 init_completion(&vfork
);
1985 wake_up_new_task(p
);
1987 /* forking complete and child started to run, tell ptracer */
1988 if (unlikely(trace
))
1989 ptrace_event_pid(trace
, pid
);
1991 if (clone_flags
& CLONE_VFORK
) {
1992 if (!wait_for_vfork_done(p
, &vfork
))
1993 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2003 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2004 /* For compatibility with architectures that call do_fork directly rather than
2005 * using the syscall entry points below. */
2006 long do_fork(unsigned long clone_flags
,
2007 unsigned long stack_start
,
2008 unsigned long stack_size
,
2009 int __user
*parent_tidptr
,
2010 int __user
*child_tidptr
)
2012 return _do_fork(clone_flags
, stack_start
, stack_size
,
2013 parent_tidptr
, child_tidptr
, 0);
2018 * Create a kernel thread.
2020 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2022 return _do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
2023 (unsigned long)arg
, NULL
, NULL
, 0);
2026 #ifdef __ARCH_WANT_SYS_FORK
2027 SYSCALL_DEFINE0(fork
)
2030 return _do_fork(SIGCHLD
, 0, 0, NULL
, NULL
, 0);
2032 /* can not support in nommu mode */
2038 #ifdef __ARCH_WANT_SYS_VFORK
2039 SYSCALL_DEFINE0(vfork
)
2041 return _do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
2046 #ifdef __ARCH_WANT_SYS_CLONE
2047 #ifdef CONFIG_CLONE_BACKWARDS
2048 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2049 int __user
*, parent_tidptr
,
2051 int __user
*, child_tidptr
)
2052 #elif defined(CONFIG_CLONE_BACKWARDS2)
2053 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2054 int __user
*, parent_tidptr
,
2055 int __user
*, child_tidptr
,
2057 #elif defined(CONFIG_CLONE_BACKWARDS3)
2058 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2060 int __user
*, parent_tidptr
,
2061 int __user
*, child_tidptr
,
2064 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2065 int __user
*, parent_tidptr
,
2066 int __user
*, child_tidptr
,
2070 return _do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
, tls
);
2074 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2076 struct task_struct
*leader
, *parent
, *child
;
2079 read_lock(&tasklist_lock
);
2080 leader
= top
= top
->group_leader
;
2082 for_each_thread(leader
, parent
) {
2083 list_for_each_entry(child
, &parent
->children
, sibling
) {
2084 res
= visitor(child
, data
);
2096 if (leader
!= top
) {
2098 parent
= child
->real_parent
;
2099 leader
= parent
->group_leader
;
2103 read_unlock(&tasklist_lock
);
2106 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2107 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2110 static void sighand_ctor(void *data
)
2112 struct sighand_struct
*sighand
= data
;
2114 spin_lock_init(&sighand
->siglock
);
2115 init_waitqueue_head(&sighand
->signalfd_wqh
);
2118 void __init
proc_caches_init(void)
2120 sighand_cachep
= kmem_cache_create("sighand_cache",
2121 sizeof(struct sighand_struct
), 0,
2122 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
2123 SLAB_NOTRACK
|SLAB_ACCOUNT
, sighand_ctor
);
2124 signal_cachep
= kmem_cache_create("signal_cache",
2125 sizeof(struct signal_struct
), 0,
2126 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2128 files_cachep
= kmem_cache_create("files_cache",
2129 sizeof(struct files_struct
), 0,
2130 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2132 fs_cachep
= kmem_cache_create("fs_cache",
2133 sizeof(struct fs_struct
), 0,
2134 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2137 * FIXME! The "sizeof(struct mm_struct)" currently includes the
2138 * whole struct cpumask for the OFFSTACK case. We could change
2139 * this to *only* allocate as much of it as required by the
2140 * maximum number of CPU's we can ever have. The cpumask_allocation
2141 * is at the end of the structure, exactly for that reason.
2143 mm_cachep
= kmem_cache_create("mm_struct",
2144 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
2145 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2147 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2149 nsproxy_cache_init();
2153 * Check constraints on flags passed to the unshare system call.
2155 static int check_unshare_flags(unsigned long unshare_flags
)
2157 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2158 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2159 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2160 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
))
2163 * Not implemented, but pretend it works if there is nothing
2164 * to unshare. Note that unsharing the address space or the
2165 * signal handlers also need to unshare the signal queues (aka
2168 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2169 if (!thread_group_empty(current
))
2172 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2173 if (atomic_read(¤t
->sighand
->count
) > 1)
2176 if (unshare_flags
& CLONE_VM
) {
2177 if (!current_is_single_threaded())
2185 * Unshare the filesystem structure if it is being shared
2187 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2189 struct fs_struct
*fs
= current
->fs
;
2191 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2194 /* don't need lock here; in the worst case we'll do useless copy */
2198 *new_fsp
= copy_fs_struct(fs
);
2206 * Unshare file descriptor table if it is being shared
2208 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2210 struct files_struct
*fd
= current
->files
;
2213 if ((unshare_flags
& CLONE_FILES
) &&
2214 (fd
&& atomic_read(&fd
->count
) > 1)) {
2215 *new_fdp
= dup_fd(fd
, &error
);
2224 * unshare allows a process to 'unshare' part of the process
2225 * context which was originally shared using clone. copy_*
2226 * functions used by do_fork() cannot be used here directly
2227 * because they modify an inactive task_struct that is being
2228 * constructed. Here we are modifying the current, active,
2231 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
2233 struct fs_struct
*fs
, *new_fs
= NULL
;
2234 struct files_struct
*fd
, *new_fd
= NULL
;
2235 struct cred
*new_cred
= NULL
;
2236 struct nsproxy
*new_nsproxy
= NULL
;
2241 * If unsharing a user namespace must also unshare the thread group
2242 * and unshare the filesystem root and working directories.
2244 if (unshare_flags
& CLONE_NEWUSER
)
2245 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2247 * If unsharing vm, must also unshare signal handlers.
2249 if (unshare_flags
& CLONE_VM
)
2250 unshare_flags
|= CLONE_SIGHAND
;
2252 * If unsharing a signal handlers, must also unshare the signal queues.
2254 if (unshare_flags
& CLONE_SIGHAND
)
2255 unshare_flags
|= CLONE_THREAD
;
2257 * If unsharing namespace, must also unshare filesystem information.
2259 if (unshare_flags
& CLONE_NEWNS
)
2260 unshare_flags
|= CLONE_FS
;
2262 err
= check_unshare_flags(unshare_flags
);
2264 goto bad_unshare_out
;
2266 * CLONE_NEWIPC must also detach from the undolist: after switching
2267 * to a new ipc namespace, the semaphore arrays from the old
2268 * namespace are unreachable.
2270 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2272 err
= unshare_fs(unshare_flags
, &new_fs
);
2274 goto bad_unshare_out
;
2275 err
= unshare_fd(unshare_flags
, &new_fd
);
2277 goto bad_unshare_cleanup_fs
;
2278 err
= unshare_userns(unshare_flags
, &new_cred
);
2280 goto bad_unshare_cleanup_fd
;
2281 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2284 goto bad_unshare_cleanup_cred
;
2286 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2289 * CLONE_SYSVSEM is equivalent to sys_exit().
2293 if (unshare_flags
& CLONE_NEWIPC
) {
2294 /* Orphan segments in old ns (see sem above). */
2296 shm_init_task(current
);
2300 switch_task_namespaces(current
, new_nsproxy
);
2306 spin_lock(&fs
->lock
);
2307 current
->fs
= new_fs
;
2312 spin_unlock(&fs
->lock
);
2316 fd
= current
->files
;
2317 current
->files
= new_fd
;
2321 task_unlock(current
);
2324 /* Install the new user namespace */
2325 commit_creds(new_cred
);
2330 bad_unshare_cleanup_cred
:
2333 bad_unshare_cleanup_fd
:
2335 put_files_struct(new_fd
);
2337 bad_unshare_cleanup_fs
:
2339 free_fs_struct(new_fs
);
2346 * Helper to unshare the files of the current task.
2347 * We don't want to expose copy_files internals to
2348 * the exec layer of the kernel.
2351 int unshare_files(struct files_struct
**displaced
)
2353 struct task_struct
*task
= current
;
2354 struct files_struct
*copy
= NULL
;
2357 error
= unshare_fd(CLONE_FILES
, ©
);
2358 if (error
|| !copy
) {
2362 *displaced
= task
->files
;
2369 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2370 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2374 int threads
= max_threads
;
2375 int min
= MIN_THREADS
;
2376 int max
= MAX_THREADS
;
2383 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2387 set_max_threads(threads
);