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>
31 #include <linux/nsproxy.h>
32 #include <linux/capability.h>
33 #include <linux/cpu.h>
34 #include <linux/cgroup.h>
35 #include <linux/security.h>
36 #include <linux/hugetlb.h>
37 #include <linux/swap.h>
38 #include <linux/syscalls.h>
39 #include <linux/jiffies.h>
40 #include <linux/tracehook.h>
41 #include <linux/futex.h>
42 #include <linux/compat.h>
43 #include <linux/task_io_accounting_ops.h>
44 #include <linux/rcupdate.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/audit.h>
48 #include <linux/memcontrol.h>
49 #include <linux/ftrace.h>
50 #include <linux/profile.h>
51 #include <linux/rmap.h>
52 #include <linux/ksm.h>
53 #include <linux/acct.h>
54 #include <linux/tsacct_kern.h>
55 #include <linux/cn_proc.h>
56 #include <linux/freezer.h>
57 #include <linux/delayacct.h>
58 #include <linux/taskstats_kern.h>
59 #include <linux/random.h>
60 #include <linux/tty.h>
61 #include <linux/proc_fs.h>
62 #include <linux/blkdev.h>
63 #include <linux/fs_struct.h>
64 #include <linux/magic.h>
65 #include <linux/perf_event.h>
66 #include <linux/posix-timers.h>
68 #include <asm/pgtable.h>
69 #include <asm/pgalloc.h>
70 #include <asm/uaccess.h>
71 #include <asm/mmu_context.h>
72 #include <asm/cacheflush.h>
73 #include <asm/tlbflush.h>
75 #include <trace/events/sched.h>
78 * Protected counters by write_lock_irq(&tasklist_lock)
80 unsigned long total_forks; /* Handle normal Linux uptimes. */
81 int nr_threads; /* The idle threads do not count.. */
83 int max_threads; /* tunable limit on nr_threads */
85 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
87 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
89 int nr_processes(void)
94 for_each_online_cpu(cpu)
95 total += per_cpu(process_counts, cpu);
100 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
101 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
102 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
103 static struct kmem_cache *task_struct_cachep;
106 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
107 static inline struct thread_info *alloc_thread_info(struct task_struct *tsk)
109 #ifdef CONFIG_DEBUG_STACK_USAGE
110 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
112 gfp_t mask = GFP_KERNEL;
114 return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER);
117 static inline void free_thread_info(struct thread_info *ti)
119 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
123 /* SLAB cache for signal_struct structures (tsk->signal) */
124 static struct kmem_cache *signal_cachep;
126 /* SLAB cache for sighand_struct structures (tsk->sighand) */
127 struct kmem_cache *sighand_cachep;
129 /* SLAB cache for files_struct structures (tsk->files) */
130 struct kmem_cache *files_cachep;
132 /* SLAB cache for fs_struct structures (tsk->fs) */
133 struct kmem_cache *fs_cachep;
135 /* SLAB cache for vm_area_struct structures */
136 struct kmem_cache *vm_area_cachep;
138 /* SLAB cache for mm_struct structures (tsk->mm) */
139 static struct kmem_cache *mm_cachep;
141 static void account_kernel_stack(struct thread_info *ti, int account)
143 struct zone *zone = page_zone(virt_to_page(ti));
145 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
148 void free_task(struct task_struct *tsk)
150 prop_local_destroy_single(&tsk->dirties);
151 account_kernel_stack(tsk->stack, -1);
152 free_thread_info(tsk->stack);
153 rt_mutex_debug_task_free(tsk);
154 ftrace_graph_exit_task(tsk);
155 free_task_struct(tsk);
157 EXPORT_SYMBOL(free_task);
159 void __put_task_struct(struct task_struct *tsk)
161 WARN_ON(!tsk->exit_state);
162 WARN_ON(atomic_read(&tsk->usage));
163 WARN_ON(tsk == current);
166 delayacct_tsk_free(tsk);
168 if (!profile_handoff_task(tsk))
173 * macro override instead of weak attribute alias, to workaround
174 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
176 #ifndef arch_task_cache_init
177 #define arch_task_cache_init()
180 void __init fork_init(unsigned long mempages)
182 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
183 #ifndef ARCH_MIN_TASKALIGN
184 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
186 /* create a slab on which task_structs can be allocated */
188 kmem_cache_create("task_struct", sizeof(struct task_struct),
189 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
192 /* do the arch specific task caches init */
193 arch_task_cache_init();
196 * The default maximum number of threads is set to a safe
197 * value: the thread structures can take up at most half
200 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
203 * we need to allow at least 20 threads to boot a system
208 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
209 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
210 init_task.signal->rlim[RLIMIT_SIGPENDING] =
211 init_task.signal->rlim[RLIMIT_NPROC];
214 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
215 struct task_struct *src)
221 static struct task_struct *dup_task_struct(struct task_struct *orig)
223 struct task_struct *tsk;
224 struct thread_info *ti;
225 unsigned long *stackend;
229 prepare_to_copy(orig);
231 tsk = alloc_task_struct();
235 ti = alloc_thread_info(tsk);
237 free_task_struct(tsk);
241 err = arch_dup_task_struct(tsk, orig);
247 err = prop_local_init_single(&tsk->dirties);
251 setup_thread_stack(tsk, orig);
252 stackend = end_of_stack(tsk);
253 *stackend = STACK_END_MAGIC; /* for overflow detection */
255 #ifdef CONFIG_CC_STACKPROTECTOR
256 tsk->stack_canary = get_random_int();
259 /* One for us, one for whoever does the "release_task()" (usually parent) */
260 atomic_set(&tsk->usage,2);
261 atomic_set(&tsk->fs_excl, 0);
262 #ifdef CONFIG_BLK_DEV_IO_TRACE
265 tsk->splice_pipe = NULL;
267 account_kernel_stack(ti, 1);
272 free_thread_info(ti);
273 free_task_struct(tsk);
278 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
280 struct vm_area_struct *mpnt, *tmp, **pprev;
281 struct rb_node **rb_link, *rb_parent;
283 unsigned long charge;
284 struct mempolicy *pol;
286 down_write(&oldmm->mmap_sem);
287 flush_cache_dup_mm(oldmm);
289 * Not linked in yet - no deadlock potential:
291 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
295 mm->mmap_cache = NULL;
296 mm->free_area_cache = oldmm->mmap_base;
297 mm->cached_hole_size = ~0UL;
299 cpumask_clear(mm_cpumask(mm));
301 rb_link = &mm->mm_rb.rb_node;
304 retval = ksm_fork(mm, oldmm);
308 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
311 if (mpnt->vm_flags & VM_DONTCOPY) {
312 long pages = vma_pages(mpnt);
313 mm->total_vm -= pages;
314 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
319 if (mpnt->vm_flags & VM_ACCOUNT) {
320 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
321 if (security_vm_enough_memory(len))
325 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
329 pol = mpol_dup(vma_policy(mpnt));
330 retval = PTR_ERR(pol);
332 goto fail_nomem_policy;
333 vma_set_policy(tmp, pol);
334 tmp->vm_flags &= ~VM_LOCKED;
340 struct inode *inode = file->f_path.dentry->d_inode;
341 struct address_space *mapping = file->f_mapping;
344 if (tmp->vm_flags & VM_DENYWRITE)
345 atomic_dec(&inode->i_writecount);
346 spin_lock(&mapping->i_mmap_lock);
347 if (tmp->vm_flags & VM_SHARED)
348 mapping->i_mmap_writable++;
349 tmp->vm_truncate_count = mpnt->vm_truncate_count;
350 flush_dcache_mmap_lock(mapping);
351 /* insert tmp into the share list, just after mpnt */
352 vma_prio_tree_add(tmp, mpnt);
353 flush_dcache_mmap_unlock(mapping);
354 spin_unlock(&mapping->i_mmap_lock);
358 * Clear hugetlb-related page reserves for children. This only
359 * affects MAP_PRIVATE mappings. Faults generated by the child
360 * are not guaranteed to succeed, even if read-only
362 if (is_vm_hugetlb_page(tmp))
363 reset_vma_resv_huge_pages(tmp);
366 * Link in the new vma and copy the page table entries.
369 pprev = &tmp->vm_next;
371 __vma_link_rb(mm, tmp, rb_link, rb_parent);
372 rb_link = &tmp->vm_rb.rb_right;
373 rb_parent = &tmp->vm_rb;
376 retval = copy_page_range(mm, oldmm, mpnt);
378 if (tmp->vm_ops && tmp->vm_ops->open)
379 tmp->vm_ops->open(tmp);
384 /* a new mm has just been created */
385 arch_dup_mmap(oldmm, mm);
388 up_write(&mm->mmap_sem);
390 up_write(&oldmm->mmap_sem);
393 kmem_cache_free(vm_area_cachep, tmp);
396 vm_unacct_memory(charge);
400 static inline int mm_alloc_pgd(struct mm_struct * mm)
402 mm->pgd = pgd_alloc(mm);
403 if (unlikely(!mm->pgd))
408 static inline void mm_free_pgd(struct mm_struct * mm)
410 pgd_free(mm, mm->pgd);
413 #define dup_mmap(mm, oldmm) (0)
414 #define mm_alloc_pgd(mm) (0)
415 #define mm_free_pgd(mm)
416 #endif /* CONFIG_MMU */
418 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
420 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
421 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
423 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
425 static int __init coredump_filter_setup(char *s)
427 default_dump_filter =
428 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
429 MMF_DUMP_FILTER_MASK;
433 __setup("coredump_filter=", coredump_filter_setup);
435 #include <linux/init_task.h>
437 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
439 atomic_set(&mm->mm_users, 1);
440 atomic_set(&mm->mm_count, 1);
441 init_rwsem(&mm->mmap_sem);
442 INIT_LIST_HEAD(&mm->mmlist);
443 mm->flags = (current->mm) ?
444 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
445 mm->core_state = NULL;
447 set_mm_counter(mm, file_rss, 0);
448 set_mm_counter(mm, anon_rss, 0);
449 spin_lock_init(&mm->page_table_lock);
450 spin_lock_init(&mm->ioctx_lock);
451 INIT_HLIST_HEAD(&mm->ioctx_list);
452 mm->free_area_cache = TASK_UNMAPPED_BASE;
453 mm->cached_hole_size = ~0UL;
454 mm_init_owner(mm, p);
456 if (likely(!mm_alloc_pgd(mm))) {
458 mmu_notifier_mm_init(mm);
467 * Allocate and initialize an mm_struct.
469 struct mm_struct * mm_alloc(void)
471 struct mm_struct * mm;
475 memset(mm, 0, sizeof(*mm));
476 mm = mm_init(mm, current);
482 * Called when the last reference to the mm
483 * is dropped: either by a lazy thread or by
484 * mmput. Free the page directory and the mm.
486 void __mmdrop(struct mm_struct *mm)
488 BUG_ON(mm == &init_mm);
491 mmu_notifier_mm_destroy(mm);
494 EXPORT_SYMBOL_GPL(__mmdrop);
497 * Decrement the use count and release all resources for an mm.
499 void mmput(struct mm_struct *mm)
503 if (atomic_dec_and_test(&mm->mm_users)) {
507 set_mm_exe_file(mm, NULL);
508 if (!list_empty(&mm->mmlist)) {
509 spin_lock(&mmlist_lock);
510 list_del(&mm->mmlist);
511 spin_unlock(&mmlist_lock);
517 EXPORT_SYMBOL_GPL(mmput);
520 * get_task_mm - acquire a reference to the task's mm
522 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
523 * this kernel workthread has transiently adopted a user mm with use_mm,
524 * to do its AIO) is not set and if so returns a reference to it, after
525 * bumping up the use count. User must release the mm via mmput()
526 * after use. Typically used by /proc and ptrace.
528 struct mm_struct *get_task_mm(struct task_struct *task)
530 struct mm_struct *mm;
535 if (task->flags & PF_KTHREAD)
538 atomic_inc(&mm->mm_users);
543 EXPORT_SYMBOL_GPL(get_task_mm);
545 /* Please note the differences between mmput and mm_release.
546 * mmput is called whenever we stop holding onto a mm_struct,
547 * error success whatever.
549 * mm_release is called after a mm_struct has been removed
550 * from the current process.
552 * This difference is important for error handling, when we
553 * only half set up a mm_struct for a new process and need to restore
554 * the old one. Because we mmput the new mm_struct before
555 * restoring the old one. . .
556 * Eric Biederman 10 January 1998
558 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
560 struct completion *vfork_done = tsk->vfork_done;
562 /* Get rid of any futexes when releasing the mm */
564 if (unlikely(tsk->robust_list))
565 exit_robust_list(tsk);
567 if (unlikely(tsk->compat_robust_list))
568 compat_exit_robust_list(tsk);
572 /* Get rid of any cached register state */
573 deactivate_mm(tsk, mm);
575 /* notify parent sleeping on vfork() */
577 tsk->vfork_done = NULL;
578 complete(vfork_done);
582 * If we're exiting normally, clear a user-space tid field if
583 * requested. We leave this alone when dying by signal, to leave
584 * the value intact in a core dump, and to save the unnecessary
585 * trouble otherwise. Userland only wants this done for a sys_exit.
587 if (tsk->clear_child_tid) {
588 if (!(tsk->flags & PF_SIGNALED) &&
589 atomic_read(&mm->mm_users) > 1) {
591 * We don't check the error code - if userspace has
592 * not set up a proper pointer then tough luck.
594 put_user(0, tsk->clear_child_tid);
595 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
598 tsk->clear_child_tid = NULL;
603 * Allocate a new mm structure and copy contents from the
604 * mm structure of the passed in task structure.
606 struct mm_struct *dup_mm(struct task_struct *tsk)
608 struct mm_struct *mm, *oldmm = current->mm;
618 memcpy(mm, oldmm, sizeof(*mm));
620 /* Initializing for Swap token stuff */
621 mm->token_priority = 0;
622 mm->last_interval = 0;
624 if (!mm_init(mm, tsk))
627 if (init_new_context(tsk, mm))
630 dup_mm_exe_file(oldmm, mm);
632 err = dup_mmap(mm, oldmm);
636 mm->hiwater_rss = get_mm_rss(mm);
637 mm->hiwater_vm = mm->total_vm;
649 * If init_new_context() failed, we cannot use mmput() to free the mm
650 * because it calls destroy_context()
657 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
659 struct mm_struct * mm, *oldmm;
662 tsk->min_flt = tsk->maj_flt = 0;
663 tsk->nvcsw = tsk->nivcsw = 0;
664 #ifdef CONFIG_DETECT_HUNG_TASK
665 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
669 tsk->active_mm = NULL;
672 * Are we cloning a kernel thread?
674 * We need to steal a active VM for that..
680 if (clone_flags & CLONE_VM) {
681 atomic_inc(&oldmm->mm_users);
692 /* Initializing for Swap token stuff */
693 mm->token_priority = 0;
694 mm->last_interval = 0;
704 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
706 struct fs_struct *fs = current->fs;
707 if (clone_flags & CLONE_FS) {
708 /* tsk->fs is already what we want */
709 write_lock(&fs->lock);
711 write_unlock(&fs->lock);
715 write_unlock(&fs->lock);
718 tsk->fs = copy_fs_struct(fs);
724 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
726 struct files_struct *oldf, *newf;
730 * A background process may not have any files ...
732 oldf = current->files;
736 if (clone_flags & CLONE_FILES) {
737 atomic_inc(&oldf->count);
741 newf = dup_fd(oldf, &error);
751 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
754 struct io_context *ioc = current->io_context;
759 * Share io context with parent, if CLONE_IO is set
761 if (clone_flags & CLONE_IO) {
762 tsk->io_context = ioc_task_link(ioc);
763 if (unlikely(!tsk->io_context))
765 } else if (ioprio_valid(ioc->ioprio)) {
766 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
767 if (unlikely(!tsk->io_context))
770 tsk->io_context->ioprio = ioc->ioprio;
776 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
778 struct sighand_struct *sig;
780 if (clone_flags & CLONE_SIGHAND) {
781 atomic_inc(¤t->sighand->count);
784 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
785 rcu_assign_pointer(tsk->sighand, sig);
788 atomic_set(&sig->count, 1);
789 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
793 void __cleanup_sighand(struct sighand_struct *sighand)
795 if (atomic_dec_and_test(&sighand->count))
796 kmem_cache_free(sighand_cachep, sighand);
801 * Initialize POSIX timer handling for a thread group.
803 static void posix_cpu_timers_init_group(struct signal_struct *sig)
805 /* Thread group counters. */
806 thread_group_cputime_init(sig);
808 /* Expiration times and increments. */
809 sig->it[CPUCLOCK_PROF].expires = cputime_zero;
810 sig->it[CPUCLOCK_PROF].incr = cputime_zero;
811 sig->it[CPUCLOCK_VIRT].expires = cputime_zero;
812 sig->it[CPUCLOCK_VIRT].incr = cputime_zero;
814 /* Cached expiration times. */
815 sig->cputime_expires.prof_exp = cputime_zero;
816 sig->cputime_expires.virt_exp = cputime_zero;
817 sig->cputime_expires.sched_exp = 0;
819 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
820 sig->cputime_expires.prof_exp =
821 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
822 sig->cputimer.running = 1;
825 /* The timer lists. */
826 INIT_LIST_HEAD(&sig->cpu_timers[0]);
827 INIT_LIST_HEAD(&sig->cpu_timers[1]);
828 INIT_LIST_HEAD(&sig->cpu_timers[2]);
831 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
833 struct signal_struct *sig;
835 if (clone_flags & CLONE_THREAD)
838 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
843 atomic_set(&sig->count, 1);
844 atomic_set(&sig->live, 1);
845 init_waitqueue_head(&sig->wait_chldexit);
847 if (clone_flags & CLONE_NEWPID)
848 sig->flags |= SIGNAL_UNKILLABLE;
849 sig->group_exit_code = 0;
850 sig->group_exit_task = NULL;
851 sig->group_stop_count = 0;
852 sig->curr_target = tsk;
853 init_sigpending(&sig->shared_pending);
854 INIT_LIST_HEAD(&sig->posix_timers);
856 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
857 sig->it_real_incr.tv64 = 0;
858 sig->real_timer.function = it_real_fn;
860 sig->leader = 0; /* session leadership doesn't inherit */
861 sig->tty_old_pgrp = NULL;
864 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
865 sig->gtime = cputime_zero;
866 sig->cgtime = cputime_zero;
867 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
868 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
869 sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
870 sig->maxrss = sig->cmaxrss = 0;
871 task_io_accounting_init(&sig->ioac);
872 sig->sum_sched_runtime = 0;
873 taskstats_tgid_init(sig);
875 task_lock(current->group_leader);
876 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
877 task_unlock(current->group_leader);
879 posix_cpu_timers_init_group(sig);
881 acct_init_pacct(&sig->pacct);
885 sig->oom_adj = current->signal->oom_adj;
890 void __cleanup_signal(struct signal_struct *sig)
892 thread_group_cputime_free(sig);
893 tty_kref_put(sig->tty);
894 kmem_cache_free(signal_cachep, sig);
897 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
899 unsigned long new_flags = p->flags;
901 new_flags &= ~PF_SUPERPRIV;
902 new_flags |= PF_FORKNOEXEC;
903 new_flags |= PF_STARTING;
904 p->flags = new_flags;
905 clear_freeze_flag(p);
908 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
910 current->clear_child_tid = tidptr;
912 return task_pid_vnr(current);
915 static void rt_mutex_init_task(struct task_struct *p)
917 spin_lock_init(&p->pi_lock);
918 #ifdef CONFIG_RT_MUTEXES
919 plist_head_init(&p->pi_waiters, &p->pi_lock);
920 p->pi_blocked_on = NULL;
924 #ifdef CONFIG_MM_OWNER
925 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
929 #endif /* CONFIG_MM_OWNER */
932 * Initialize POSIX timer handling for a single task.
934 static void posix_cpu_timers_init(struct task_struct *tsk)
936 tsk->cputime_expires.prof_exp = cputime_zero;
937 tsk->cputime_expires.virt_exp = cputime_zero;
938 tsk->cputime_expires.sched_exp = 0;
939 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
940 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
941 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
945 * This creates a new process as a copy of the old one,
946 * but does not actually start it yet.
948 * It copies the registers, and all the appropriate
949 * parts of the process environment (as per the clone
950 * flags). The actual kick-off is left to the caller.
952 static struct task_struct *copy_process(unsigned long clone_flags,
953 unsigned long stack_start,
954 struct pt_regs *regs,
955 unsigned long stack_size,
956 int __user *child_tidptr,
961 struct task_struct *p;
962 int cgroup_callbacks_done = 0;
964 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
965 return ERR_PTR(-EINVAL);
968 * Thread groups must share signals as well, and detached threads
969 * can only be started up within the thread group.
971 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
972 return ERR_PTR(-EINVAL);
975 * Shared signal handlers imply shared VM. By way of the above,
976 * thread groups also imply shared VM. Blocking this case allows
977 * for various simplifications in other code.
979 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
980 return ERR_PTR(-EINVAL);
983 * Siblings of global init remain as zombies on exit since they are
984 * not reaped by their parent (swapper). To solve this and to avoid
985 * multi-rooted process trees, prevent global and container-inits
986 * from creating siblings.
988 if ((clone_flags & CLONE_PARENT) &&
989 current->signal->flags & SIGNAL_UNKILLABLE)
990 return ERR_PTR(-EINVAL);
992 retval = security_task_create(clone_flags);
997 p = dup_task_struct(current);
1001 ftrace_graph_init_task(p);
1003 rt_mutex_init_task(p);
1005 #ifdef CONFIG_PROVE_LOCKING
1006 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1007 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1010 if (atomic_read(&p->real_cred->user->processes) >=
1011 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
1012 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1013 p->real_cred->user != INIT_USER)
1017 retval = copy_creds(p, clone_flags);
1022 * If multiple threads are within copy_process(), then this check
1023 * triggers too late. This doesn't hurt, the check is only there
1024 * to stop root fork bombs.
1027 if (nr_threads >= max_threads)
1028 goto bad_fork_cleanup_count;
1030 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1031 goto bad_fork_cleanup_count;
1033 if (p->binfmt && !try_module_get(p->binfmt->module))
1034 goto bad_fork_cleanup_put_domain;
1037 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1038 copy_flags(clone_flags, p);
1039 INIT_LIST_HEAD(&p->children);
1040 INIT_LIST_HEAD(&p->sibling);
1041 rcu_copy_process(p);
1042 p->vfork_done = NULL;
1043 spin_lock_init(&p->alloc_lock);
1045 init_sigpending(&p->pending);
1047 p->utime = cputime_zero;
1048 p->stime = cputime_zero;
1049 p->gtime = cputime_zero;
1050 p->utimescaled = cputime_zero;
1051 p->stimescaled = cputime_zero;
1052 p->prev_utime = cputime_zero;
1053 p->prev_stime = cputime_zero;
1055 p->default_timer_slack_ns = current->timer_slack_ns;
1057 task_io_accounting_init(&p->ioac);
1058 acct_clear_integrals(p);
1060 posix_cpu_timers_init(p);
1062 p->lock_depth = -1; /* -1 = no lock */
1063 do_posix_clock_monotonic_gettime(&p->start_time);
1064 p->real_start_time = p->start_time;
1065 monotonic_to_bootbased(&p->real_start_time);
1066 p->io_context = NULL;
1067 p->audit_context = NULL;
1070 p->mempolicy = mpol_dup(p->mempolicy);
1071 if (IS_ERR(p->mempolicy)) {
1072 retval = PTR_ERR(p->mempolicy);
1073 p->mempolicy = NULL;
1074 goto bad_fork_cleanup_cgroup;
1076 mpol_fix_fork_child_flag(p);
1078 #ifdef CONFIG_TRACE_IRQFLAGS
1080 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1081 p->hardirqs_enabled = 1;
1083 p->hardirqs_enabled = 0;
1085 p->hardirq_enable_ip = 0;
1086 p->hardirq_enable_event = 0;
1087 p->hardirq_disable_ip = _THIS_IP_;
1088 p->hardirq_disable_event = 0;
1089 p->softirqs_enabled = 1;
1090 p->softirq_enable_ip = _THIS_IP_;
1091 p->softirq_enable_event = 0;
1092 p->softirq_disable_ip = 0;
1093 p->softirq_disable_event = 0;
1094 p->hardirq_context = 0;
1095 p->softirq_context = 0;
1097 #ifdef CONFIG_LOCKDEP
1098 p->lockdep_depth = 0; /* no locks held yet */
1099 p->curr_chain_key = 0;
1100 p->lockdep_recursion = 0;
1103 #ifdef CONFIG_DEBUG_MUTEXES
1104 p->blocked_on = NULL; /* not blocked yet */
1109 p->stack_start = stack_start;
1111 /* Perform scheduler related setup. Assign this task to a CPU. */
1112 sched_fork(p, clone_flags);
1114 retval = perf_event_init_task(p);
1116 goto bad_fork_cleanup_policy;
1118 if ((retval = audit_alloc(p)))
1119 goto bad_fork_cleanup_policy;
1120 /* copy all the process information */
1121 if ((retval = copy_semundo(clone_flags, p)))
1122 goto bad_fork_cleanup_audit;
1123 if ((retval = copy_files(clone_flags, p)))
1124 goto bad_fork_cleanup_semundo;
1125 if ((retval = copy_fs(clone_flags, p)))
1126 goto bad_fork_cleanup_files;
1127 if ((retval = copy_sighand(clone_flags, p)))
1128 goto bad_fork_cleanup_fs;
1129 if ((retval = copy_signal(clone_flags, p)))
1130 goto bad_fork_cleanup_sighand;
1131 if ((retval = copy_mm(clone_flags, p)))
1132 goto bad_fork_cleanup_signal;
1133 if ((retval = copy_namespaces(clone_flags, p)))
1134 goto bad_fork_cleanup_mm;
1135 if ((retval = copy_io(clone_flags, p)))
1136 goto bad_fork_cleanup_namespaces;
1137 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1139 goto bad_fork_cleanup_io;
1141 if (pid != &init_struct_pid) {
1143 pid = alloc_pid(p->nsproxy->pid_ns);
1145 goto bad_fork_cleanup_io;
1147 if (clone_flags & CLONE_NEWPID) {
1148 retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
1150 goto bad_fork_free_pid;
1154 p->pid = pid_nr(pid);
1156 if (clone_flags & CLONE_THREAD)
1157 p->tgid = current->tgid;
1159 if (current->nsproxy != p->nsproxy) {
1160 retval = ns_cgroup_clone(p, pid);
1162 goto bad_fork_free_pid;
1165 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1167 * Clear TID on mm_release()?
1169 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1171 p->robust_list = NULL;
1172 #ifdef CONFIG_COMPAT
1173 p->compat_robust_list = NULL;
1175 INIT_LIST_HEAD(&p->pi_state_list);
1176 p->pi_state_cache = NULL;
1179 * sigaltstack should be cleared when sharing the same VM
1181 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1182 p->sas_ss_sp = p->sas_ss_size = 0;
1185 * Syscall tracing should be turned off in the child regardless
1188 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1189 #ifdef TIF_SYSCALL_EMU
1190 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1192 clear_all_latency_tracing(p);
1194 /* ok, now we should be set up.. */
1195 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1196 p->pdeath_signal = 0;
1200 * Ok, make it visible to the rest of the system.
1201 * We dont wake it up yet.
1203 p->group_leader = p;
1204 INIT_LIST_HEAD(&p->thread_group);
1206 /* Now that the task is set up, run cgroup callbacks if
1207 * necessary. We need to run them before the task is visible
1208 * on the tasklist. */
1209 cgroup_fork_callbacks(p);
1210 cgroup_callbacks_done = 1;
1212 /* Need tasklist lock for parent etc handling! */
1213 write_lock_irq(&tasklist_lock);
1216 * The task hasn't been attached yet, so its cpus_allowed mask will
1217 * not be changed, nor will its assigned CPU.
1219 * The cpus_allowed mask of the parent may have changed after it was
1220 * copied first time - so re-copy it here, then check the child's CPU
1221 * to ensure it is on a valid CPU (and if not, just force it back to
1222 * parent's CPU). This avoids alot of nasty races.
1224 p->cpus_allowed = current->cpus_allowed;
1225 p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
1226 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1227 !cpu_online(task_cpu(p))))
1228 set_task_cpu(p, smp_processor_id());
1230 /* CLONE_PARENT re-uses the old parent */
1231 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1232 p->real_parent = current->real_parent;
1233 p->parent_exec_id = current->parent_exec_id;
1235 p->real_parent = current;
1236 p->parent_exec_id = current->self_exec_id;
1239 spin_lock(¤t->sighand->siglock);
1242 * Process group and session signals need to be delivered to just the
1243 * parent before the fork or both the parent and the child after the
1244 * fork. Restart if a signal comes in before we add the new process to
1245 * it's process group.
1246 * A fatal signal pending means that current will exit, so the new
1247 * thread can't slip out of an OOM kill (or normal SIGKILL).
1249 recalc_sigpending();
1250 if (signal_pending(current)) {
1251 spin_unlock(¤t->sighand->siglock);
1252 write_unlock_irq(&tasklist_lock);
1253 retval = -ERESTARTNOINTR;
1254 goto bad_fork_free_pid;
1257 if (clone_flags & CLONE_THREAD) {
1258 atomic_inc(¤t->signal->count);
1259 atomic_inc(¤t->signal->live);
1260 p->group_leader = current->group_leader;
1261 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1264 if (likely(p->pid)) {
1265 list_add_tail(&p->sibling, &p->real_parent->children);
1266 tracehook_finish_clone(p, clone_flags, trace);
1268 if (thread_group_leader(p)) {
1269 if (clone_flags & CLONE_NEWPID)
1270 p->nsproxy->pid_ns->child_reaper = p;
1272 p->signal->leader_pid = pid;
1273 tty_kref_put(p->signal->tty);
1274 p->signal->tty = tty_kref_get(current->signal->tty);
1275 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1276 attach_pid(p, PIDTYPE_SID, task_session(current));
1277 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1278 __get_cpu_var(process_counts)++;
1280 attach_pid(p, PIDTYPE_PID, pid);
1285 spin_unlock(¤t->sighand->siglock);
1286 write_unlock_irq(&tasklist_lock);
1287 proc_fork_connector(p);
1288 cgroup_post_fork(p);
1293 if (pid != &init_struct_pid)
1295 bad_fork_cleanup_io:
1296 put_io_context(p->io_context);
1297 bad_fork_cleanup_namespaces:
1298 exit_task_namespaces(p);
1299 bad_fork_cleanup_mm:
1302 bad_fork_cleanup_signal:
1303 if (!(clone_flags & CLONE_THREAD))
1304 __cleanup_signal(p->signal);
1305 bad_fork_cleanup_sighand:
1306 __cleanup_sighand(p->sighand);
1307 bad_fork_cleanup_fs:
1308 exit_fs(p); /* blocking */
1309 bad_fork_cleanup_files:
1310 exit_files(p); /* blocking */
1311 bad_fork_cleanup_semundo:
1313 bad_fork_cleanup_audit:
1315 bad_fork_cleanup_policy:
1316 perf_event_free_task(p);
1318 mpol_put(p->mempolicy);
1319 bad_fork_cleanup_cgroup:
1321 cgroup_exit(p, cgroup_callbacks_done);
1322 delayacct_tsk_free(p);
1324 module_put(p->binfmt->module);
1325 bad_fork_cleanup_put_domain:
1326 module_put(task_thread_info(p)->exec_domain->module);
1327 bad_fork_cleanup_count:
1328 atomic_dec(&p->cred->user->processes);
1333 return ERR_PTR(retval);
1336 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1338 memset(regs, 0, sizeof(struct pt_regs));
1342 struct task_struct * __cpuinit fork_idle(int cpu)
1344 struct task_struct *task;
1345 struct pt_regs regs;
1347 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1348 &init_struct_pid, 0);
1350 init_idle(task, cpu);
1356 * Ok, this is the main fork-routine.
1358 * It copies the process, and if successful kick-starts
1359 * it and waits for it to finish using the VM if required.
1361 long do_fork(unsigned long clone_flags,
1362 unsigned long stack_start,
1363 struct pt_regs *regs,
1364 unsigned long stack_size,
1365 int __user *parent_tidptr,
1366 int __user *child_tidptr)
1368 struct task_struct *p;
1373 * Do some preliminary argument and permissions checking before we
1374 * actually start allocating stuff
1376 if (clone_flags & CLONE_NEWUSER) {
1377 if (clone_flags & CLONE_THREAD)
1379 /* hopefully this check will go away when userns support is
1382 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1383 !capable(CAP_SETGID))
1388 * We hope to recycle these flags after 2.6.26
1390 if (unlikely(clone_flags & CLONE_STOPPED)) {
1391 static int __read_mostly count = 100;
1393 if (count > 0 && printk_ratelimit()) {
1394 char comm[TASK_COMM_LEN];
1397 printk(KERN_INFO "fork(): process `%s' used deprecated "
1398 "clone flags 0x%lx\n",
1399 get_task_comm(comm, current),
1400 clone_flags & CLONE_STOPPED);
1405 * When called from kernel_thread, don't do user tracing stuff.
1407 if (likely(user_mode(regs)))
1408 trace = tracehook_prepare_clone(clone_flags);
1410 p = copy_process(clone_flags, stack_start, regs, stack_size,
1411 child_tidptr, NULL, trace);
1413 * Do this prior waking up the new thread - the thread pointer
1414 * might get invalid after that point, if the thread exits quickly.
1417 struct completion vfork;
1419 trace_sched_process_fork(current, p);
1421 nr = task_pid_vnr(p);
1423 if (clone_flags & CLONE_PARENT_SETTID)
1424 put_user(nr, parent_tidptr);
1426 if (clone_flags & CLONE_VFORK) {
1427 p->vfork_done = &vfork;
1428 init_completion(&vfork);
1431 audit_finish_fork(p);
1432 tracehook_report_clone(regs, clone_flags, nr, p);
1435 * We set PF_STARTING at creation in case tracing wants to
1436 * use this to distinguish a fully live task from one that
1437 * hasn't gotten to tracehook_report_clone() yet. Now we
1438 * clear it and set the child going.
1440 p->flags &= ~PF_STARTING;
1442 if (unlikely(clone_flags & CLONE_STOPPED)) {
1444 * We'll start up with an immediate SIGSTOP.
1446 sigaddset(&p->pending.signal, SIGSTOP);
1447 set_tsk_thread_flag(p, TIF_SIGPENDING);
1448 __set_task_state(p, TASK_STOPPED);
1450 wake_up_new_task(p, clone_flags);
1453 tracehook_report_clone_complete(trace, regs,
1454 clone_flags, nr, p);
1456 if (clone_flags & CLONE_VFORK) {
1457 freezer_do_not_count();
1458 wait_for_completion(&vfork);
1460 tracehook_report_vfork_done(p, nr);
1468 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1469 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1472 static void sighand_ctor(void *data)
1474 struct sighand_struct *sighand = data;
1476 spin_lock_init(&sighand->siglock);
1477 init_waitqueue_head(&sighand->signalfd_wqh);
1480 void __init proc_caches_init(void)
1482 sighand_cachep = kmem_cache_create("sighand_cache",
1483 sizeof(struct sighand_struct), 0,
1484 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1485 SLAB_NOTRACK, sighand_ctor);
1486 signal_cachep = kmem_cache_create("signal_cache",
1487 sizeof(struct signal_struct), 0,
1488 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1489 files_cachep = kmem_cache_create("files_cache",
1490 sizeof(struct files_struct), 0,
1491 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1492 fs_cachep = kmem_cache_create("fs_cache",
1493 sizeof(struct fs_struct), 0,
1494 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1495 mm_cachep = kmem_cache_create("mm_struct",
1496 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1497 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1498 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1503 * Check constraints on flags passed to the unshare system call and
1504 * force unsharing of additional process context as appropriate.
1506 static void check_unshare_flags(unsigned long *flags_ptr)
1509 * If unsharing a thread from a thread group, must also
1512 if (*flags_ptr & CLONE_THREAD)
1513 *flags_ptr |= CLONE_VM;
1516 * If unsharing vm, must also unshare signal handlers.
1518 if (*flags_ptr & CLONE_VM)
1519 *flags_ptr |= CLONE_SIGHAND;
1522 * If unsharing signal handlers and the task was created
1523 * using CLONE_THREAD, then must unshare the thread
1525 if ((*flags_ptr & CLONE_SIGHAND) &&
1526 (atomic_read(¤t->signal->count) > 1))
1527 *flags_ptr |= CLONE_THREAD;
1530 * If unsharing namespace, must also unshare filesystem information.
1532 if (*flags_ptr & CLONE_NEWNS)
1533 *flags_ptr |= CLONE_FS;
1537 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1539 static int unshare_thread(unsigned long unshare_flags)
1541 if (unshare_flags & CLONE_THREAD)
1548 * Unshare the filesystem structure if it is being shared
1550 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1552 struct fs_struct *fs = current->fs;
1554 if (!(unshare_flags & CLONE_FS) || !fs)
1557 /* don't need lock here; in the worst case we'll do useless copy */
1561 *new_fsp = copy_fs_struct(fs);
1569 * Unsharing of sighand is not supported yet
1571 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
1573 struct sighand_struct *sigh = current->sighand;
1575 if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)
1582 * Unshare vm if it is being shared
1584 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
1586 struct mm_struct *mm = current->mm;
1588 if ((unshare_flags & CLONE_VM) &&
1589 (mm && atomic_read(&mm->mm_users) > 1)) {
1597 * Unshare file descriptor table if it is being shared
1599 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1601 struct files_struct *fd = current->files;
1604 if ((unshare_flags & CLONE_FILES) &&
1605 (fd && atomic_read(&fd->count) > 1)) {
1606 *new_fdp = dup_fd(fd, &error);
1615 * unshare allows a process to 'unshare' part of the process
1616 * context which was originally shared using clone. copy_*
1617 * functions used by do_fork() cannot be used here directly
1618 * because they modify an inactive task_struct that is being
1619 * constructed. Here we are modifying the current, active,
1622 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1625 struct fs_struct *fs, *new_fs = NULL;
1626 struct sighand_struct *new_sigh = NULL;
1627 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
1628 struct files_struct *fd, *new_fd = NULL;
1629 struct nsproxy *new_nsproxy = NULL;
1632 check_unshare_flags(&unshare_flags);
1634 /* Return -EINVAL for all unsupported flags */
1636 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1637 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1638 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1639 goto bad_unshare_out;
1642 * CLONE_NEWIPC must also detach from the undolist: after switching
1643 * to a new ipc namespace, the semaphore arrays from the old
1644 * namespace are unreachable.
1646 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1648 if ((err = unshare_thread(unshare_flags)))
1649 goto bad_unshare_out;
1650 if ((err = unshare_fs(unshare_flags, &new_fs)))
1651 goto bad_unshare_cleanup_thread;
1652 if ((err = unshare_sighand(unshare_flags, &new_sigh)))
1653 goto bad_unshare_cleanup_fs;
1654 if ((err = unshare_vm(unshare_flags, &new_mm)))
1655 goto bad_unshare_cleanup_sigh;
1656 if ((err = unshare_fd(unshare_flags, &new_fd)))
1657 goto bad_unshare_cleanup_vm;
1658 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
1660 goto bad_unshare_cleanup_fd;
1662 if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) {
1665 * CLONE_SYSVSEM is equivalent to sys_exit().
1671 switch_task_namespaces(current, new_nsproxy);
1679 write_lock(&fs->lock);
1680 current->fs = new_fs;
1685 write_unlock(&fs->lock);
1690 active_mm = current->active_mm;
1691 current->mm = new_mm;
1692 current->active_mm = new_mm;
1693 activate_mm(active_mm, new_mm);
1698 fd = current->files;
1699 current->files = new_fd;
1703 task_unlock(current);
1707 put_nsproxy(new_nsproxy);
1709 bad_unshare_cleanup_fd:
1711 put_files_struct(new_fd);
1713 bad_unshare_cleanup_vm:
1717 bad_unshare_cleanup_sigh:
1719 if (atomic_dec_and_test(&new_sigh->count))
1720 kmem_cache_free(sighand_cachep, new_sigh);
1722 bad_unshare_cleanup_fs:
1724 free_fs_struct(new_fs);
1726 bad_unshare_cleanup_thread:
1732 * Helper to unshare the files of the current task.
1733 * We don't want to expose copy_files internals to
1734 * the exec layer of the kernel.
1737 int unshare_files(struct files_struct **displaced)
1739 struct task_struct *task = current;
1740 struct files_struct *copy = NULL;
1743 error = unshare_fd(CLONE_FILES, ©);
1744 if (error || !copy) {
1748 *displaced = task->files;