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/futex.h>
41 #include <linux/compat.h>
42 #include <linux/kthread.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/proc_fs.h>
51 #include <linux/profile.h>
52 #include <linux/rmap.h>
53 #include <linux/ksm.h>
54 #include <linux/acct.h>
55 #include <linux/tsacct_kern.h>
56 #include <linux/cn_proc.h>
57 #include <linux/freezer.h>
58 #include <linux/delayacct.h>
59 #include <linux/taskstats_kern.h>
60 #include <linux/random.h>
61 #include <linux/tty.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>
67 #include <linux/user-return-notifier.h>
68 #include <linux/oom.h>
69 #include <linux/khugepaged.h>
70 #include <linux/signalfd.h>
72 #include <asm/pgtable.h>
73 #include <asm/pgalloc.h>
74 #include <asm/uaccess.h>
75 #include <asm/mmu_context.h>
76 #include <asm/cacheflush.h>
77 #include <asm/tlbflush.h>
79 #include <trace/events/sched.h>
82 * Protected counters by write_lock_irq(&tasklist_lock)
84 unsigned long total_forks; /* Handle normal Linux uptimes. */
85 int nr_threads; /* The idle threads do not count.. */
87 int max_threads; /* tunable limit on nr_threads */
89 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
91 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
93 #ifdef CONFIG_PROVE_RCU
94 int lockdep_tasklist_lock_is_held(void)
96 return lockdep_is_held(&tasklist_lock);
98 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
99 #endif /* #ifdef CONFIG_PROVE_RCU */
101 int nr_processes(void)
106 for_each_possible_cpu(cpu)
107 total += per_cpu(process_counts, cpu);
112 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
113 # define alloc_task_struct_node(node) \
114 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
115 # define free_task_struct(tsk) \
116 kmem_cache_free(task_struct_cachep, (tsk))
117 static struct kmem_cache *task_struct_cachep;
120 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
121 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
124 #ifdef CONFIG_DEBUG_STACK_USAGE
125 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
127 gfp_t mask = GFP_KERNEL;
129 struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER);
131 return page ? page_address(page) : NULL;
134 static inline void free_thread_info(struct thread_info *ti)
136 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
140 /* SLAB cache for signal_struct structures (tsk->signal) */
141 static struct kmem_cache *signal_cachep;
143 /* SLAB cache for sighand_struct structures (tsk->sighand) */
144 struct kmem_cache *sighand_cachep;
146 /* SLAB cache for files_struct structures (tsk->files) */
147 struct kmem_cache *files_cachep;
149 /* SLAB cache for fs_struct structures (tsk->fs) */
150 struct kmem_cache *fs_cachep;
152 /* SLAB cache for vm_area_struct structures */
153 struct kmem_cache *vm_area_cachep;
155 /* SLAB cache for mm_struct structures (tsk->mm) */
156 static struct kmem_cache *mm_cachep;
158 static void account_kernel_stack(struct thread_info *ti, int account)
160 struct zone *zone = page_zone(virt_to_page(ti));
162 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
165 void free_task(struct task_struct *tsk)
167 account_kernel_stack(tsk->stack, -1);
168 free_thread_info(tsk->stack);
169 rt_mutex_debug_task_free(tsk);
170 ftrace_graph_exit_task(tsk);
171 free_task_struct(tsk);
173 EXPORT_SYMBOL(free_task);
175 static inline void free_signal_struct(struct signal_struct *sig)
177 taskstats_tgid_free(sig);
178 sched_autogroup_exit(sig);
179 kmem_cache_free(signal_cachep, sig);
182 static inline void put_signal_struct(struct signal_struct *sig)
184 if (atomic_dec_and_test(&sig->sigcnt))
185 free_signal_struct(sig);
188 void __put_task_struct(struct task_struct *tsk)
190 WARN_ON(!tsk->exit_state);
191 WARN_ON(atomic_read(&tsk->usage));
192 WARN_ON(tsk == current);
195 delayacct_tsk_free(tsk);
196 put_signal_struct(tsk->signal);
198 if (!profile_handoff_task(tsk))
201 EXPORT_SYMBOL_GPL(__put_task_struct);
204 * macro override instead of weak attribute alias, to workaround
205 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
207 #ifndef arch_task_cache_init
208 #define arch_task_cache_init()
211 void __init fork_init(unsigned long mempages)
213 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
214 #ifndef ARCH_MIN_TASKALIGN
215 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
217 /* create a slab on which task_structs can be allocated */
219 kmem_cache_create("task_struct", sizeof(struct task_struct),
220 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
223 /* do the arch specific task caches init */
224 arch_task_cache_init();
227 * The default maximum number of threads is set to a safe
228 * value: the thread structures can take up at most half
231 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
234 * we need to allow at least 20 threads to boot a system
236 if (max_threads < 20)
239 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
240 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
241 init_task.signal->rlim[RLIMIT_SIGPENDING] =
242 init_task.signal->rlim[RLIMIT_NPROC];
245 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
246 struct task_struct *src)
252 static struct task_struct *dup_task_struct(struct task_struct *orig)
254 struct task_struct *tsk;
255 struct thread_info *ti;
256 unsigned long *stackend;
257 int node = tsk_fork_get_node(orig);
260 prepare_to_copy(orig);
262 tsk = alloc_task_struct_node(node);
266 ti = alloc_thread_info_node(tsk, node);
268 free_task_struct(tsk);
272 err = arch_dup_task_struct(tsk, orig);
278 setup_thread_stack(tsk, orig);
279 clear_user_return_notifier(tsk);
280 clear_tsk_need_resched(tsk);
281 stackend = end_of_stack(tsk);
282 *stackend = STACK_END_MAGIC; /* for overflow detection */
284 #ifdef CONFIG_CC_STACKPROTECTOR
285 tsk->stack_canary = get_random_int();
289 * One for us, one for whoever does the "release_task()" (usually
292 atomic_set(&tsk->usage, 2);
293 #ifdef CONFIG_BLK_DEV_IO_TRACE
296 tsk->splice_pipe = NULL;
298 account_kernel_stack(ti, 1);
303 free_thread_info(ti);
304 free_task_struct(tsk);
309 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
311 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
312 struct rb_node **rb_link, *rb_parent;
314 unsigned long charge;
315 struct mempolicy *pol;
317 down_write(&oldmm->mmap_sem);
318 flush_cache_dup_mm(oldmm);
320 * Not linked in yet - no deadlock potential:
322 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
326 mm->mmap_cache = NULL;
327 mm->free_area_cache = oldmm->mmap_base;
328 mm->cached_hole_size = ~0UL;
330 cpumask_clear(mm_cpumask(mm));
332 rb_link = &mm->mm_rb.rb_node;
335 retval = ksm_fork(mm, oldmm);
338 retval = khugepaged_fork(mm, oldmm);
343 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
346 if (mpnt->vm_flags & VM_DONTCOPY) {
347 long pages = vma_pages(mpnt);
348 mm->total_vm -= pages;
349 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
354 if (mpnt->vm_flags & VM_ACCOUNT) {
355 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
356 if (security_vm_enough_memory(len))
360 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
364 INIT_LIST_HEAD(&tmp->anon_vma_chain);
365 pol = mpol_dup(vma_policy(mpnt));
366 retval = PTR_ERR(pol);
368 goto fail_nomem_policy;
369 vma_set_policy(tmp, pol);
371 if (anon_vma_fork(tmp, mpnt))
372 goto fail_nomem_anon_vma_fork;
373 tmp->vm_flags &= ~VM_LOCKED;
374 tmp->vm_next = tmp->vm_prev = NULL;
377 struct inode *inode = file->f_path.dentry->d_inode;
378 struct address_space *mapping = file->f_mapping;
381 if (tmp->vm_flags & VM_DENYWRITE)
382 atomic_dec(&inode->i_writecount);
383 mutex_lock(&mapping->i_mmap_mutex);
384 if (tmp->vm_flags & VM_SHARED)
385 mapping->i_mmap_writable++;
386 flush_dcache_mmap_lock(mapping);
387 /* insert tmp into the share list, just after mpnt */
388 vma_prio_tree_add(tmp, mpnt);
389 flush_dcache_mmap_unlock(mapping);
390 mutex_unlock(&mapping->i_mmap_mutex);
394 * Clear hugetlb-related page reserves for children. This only
395 * affects MAP_PRIVATE mappings. Faults generated by the child
396 * are not guaranteed to succeed, even if read-only
398 if (is_vm_hugetlb_page(tmp))
399 reset_vma_resv_huge_pages(tmp);
402 * Link in the new vma and copy the page table entries.
405 pprev = &tmp->vm_next;
409 __vma_link_rb(mm, tmp, rb_link, rb_parent);
410 rb_link = &tmp->vm_rb.rb_right;
411 rb_parent = &tmp->vm_rb;
414 retval = copy_page_range(mm, oldmm, mpnt);
416 if (tmp->vm_ops && tmp->vm_ops->open)
417 tmp->vm_ops->open(tmp);
422 /* a new mm has just been created */
423 arch_dup_mmap(oldmm, mm);
426 up_write(&mm->mmap_sem);
428 up_write(&oldmm->mmap_sem);
430 fail_nomem_anon_vma_fork:
433 kmem_cache_free(vm_area_cachep, tmp);
436 vm_unacct_memory(charge);
440 static inline int mm_alloc_pgd(struct mm_struct *mm)
442 mm->pgd = pgd_alloc(mm);
443 if (unlikely(!mm->pgd))
448 static inline void mm_free_pgd(struct mm_struct *mm)
450 pgd_free(mm, mm->pgd);
453 #define dup_mmap(mm, oldmm) (0)
454 #define mm_alloc_pgd(mm) (0)
455 #define mm_free_pgd(mm)
456 #endif /* CONFIG_MMU */
458 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
460 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
461 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
463 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
465 static int __init coredump_filter_setup(char *s)
467 default_dump_filter =
468 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
469 MMF_DUMP_FILTER_MASK;
473 __setup("coredump_filter=", coredump_filter_setup);
475 #include <linux/init_task.h>
477 static void mm_init_aio(struct mm_struct *mm)
480 spin_lock_init(&mm->ioctx_lock);
481 INIT_HLIST_HEAD(&mm->ioctx_list);
485 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
487 atomic_set(&mm->mm_users, 1);
488 atomic_set(&mm->mm_count, 1);
489 init_rwsem(&mm->mmap_sem);
490 INIT_LIST_HEAD(&mm->mmlist);
491 mm->flags = (current->mm) ?
492 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
493 mm->core_state = NULL;
495 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
496 spin_lock_init(&mm->page_table_lock);
497 mm->free_area_cache = TASK_UNMAPPED_BASE;
498 mm->cached_hole_size = ~0UL;
500 mm_init_owner(mm, p);
502 if (likely(!mm_alloc_pgd(mm))) {
504 mmu_notifier_mm_init(mm);
513 * Allocate and initialize an mm_struct.
515 struct mm_struct *mm_alloc(void)
517 struct mm_struct *mm;
523 memset(mm, 0, sizeof(*mm));
525 return mm_init(mm, current);
529 * Called when the last reference to the mm
530 * is dropped: either by a lazy thread or by
531 * mmput. Free the page directory and the mm.
533 void __mmdrop(struct mm_struct *mm)
535 BUG_ON(mm == &init_mm);
538 mmu_notifier_mm_destroy(mm);
539 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
540 VM_BUG_ON(mm->pmd_huge_pte);
544 EXPORT_SYMBOL_GPL(__mmdrop);
547 * Decrement the use count and release all resources for an mm.
549 void mmput(struct mm_struct *mm)
553 if (atomic_dec_and_test(&mm->mm_users)) {
556 khugepaged_exit(mm); /* must run before exit_mmap */
558 set_mm_exe_file(mm, NULL);
559 if (!list_empty(&mm->mmlist)) {
560 spin_lock(&mmlist_lock);
561 list_del(&mm->mmlist);
562 spin_unlock(&mmlist_lock);
566 module_put(mm->binfmt->module);
570 EXPORT_SYMBOL_GPL(mmput);
573 * We added or removed a vma mapping the executable. The vmas are only mapped
574 * during exec and are not mapped with the mmap system call.
575 * Callers must hold down_write() on the mm's mmap_sem for these
577 void added_exe_file_vma(struct mm_struct *mm)
579 mm->num_exe_file_vmas++;
582 void removed_exe_file_vma(struct mm_struct *mm)
584 mm->num_exe_file_vmas--;
585 if ((mm->num_exe_file_vmas == 0) && mm->exe_file) {
592 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
595 get_file(new_exe_file);
598 mm->exe_file = new_exe_file;
599 mm->num_exe_file_vmas = 0;
602 struct file *get_mm_exe_file(struct mm_struct *mm)
604 struct file *exe_file;
606 /* We need mmap_sem to protect against races with removal of
607 * VM_EXECUTABLE vmas */
608 down_read(&mm->mmap_sem);
609 exe_file = mm->exe_file;
612 up_read(&mm->mmap_sem);
616 static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
618 /* It's safe to write the exe_file pointer without exe_file_lock because
619 * this is called during fork when the task is not yet in /proc */
620 newmm->exe_file = get_mm_exe_file(oldmm);
624 * get_task_mm - acquire a reference to the task's mm
626 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
627 * this kernel workthread has transiently adopted a user mm with use_mm,
628 * to do its AIO) is not set and if so returns a reference to it, after
629 * bumping up the use count. User must release the mm via mmput()
630 * after use. Typically used by /proc and ptrace.
632 struct mm_struct *get_task_mm(struct task_struct *task)
634 struct mm_struct *mm;
639 if (task->flags & PF_KTHREAD)
642 atomic_inc(&mm->mm_users);
647 EXPORT_SYMBOL_GPL(get_task_mm);
649 /* Please note the differences between mmput and mm_release.
650 * mmput is called whenever we stop holding onto a mm_struct,
651 * error success whatever.
653 * mm_release is called after a mm_struct has been removed
654 * from the current process.
656 * This difference is important for error handling, when we
657 * only half set up a mm_struct for a new process and need to restore
658 * the old one. Because we mmput the new mm_struct before
659 * restoring the old one. . .
660 * Eric Biederman 10 January 1998
662 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
664 struct completion *vfork_done = tsk->vfork_done;
666 /* Get rid of any futexes when releasing the mm */
668 if (unlikely(tsk->robust_list)) {
669 exit_robust_list(tsk);
670 tsk->robust_list = NULL;
673 if (unlikely(tsk->compat_robust_list)) {
674 compat_exit_robust_list(tsk);
675 tsk->compat_robust_list = NULL;
678 if (unlikely(!list_empty(&tsk->pi_state_list)))
679 exit_pi_state_list(tsk);
682 /* Get rid of any cached register state */
683 deactivate_mm(tsk, mm);
685 /* notify parent sleeping on vfork() */
687 tsk->vfork_done = NULL;
688 complete(vfork_done);
692 * If we're exiting normally, clear a user-space tid field if
693 * requested. We leave this alone when dying by signal, to leave
694 * the value intact in a core dump, and to save the unnecessary
695 * trouble otherwise. Userland only wants this done for a sys_exit.
697 if (tsk->clear_child_tid) {
698 if (!(tsk->flags & PF_SIGNALED) &&
699 atomic_read(&mm->mm_users) > 1) {
701 * We don't check the error code - if userspace has
702 * not set up a proper pointer then tough luck.
704 put_user(0, tsk->clear_child_tid);
705 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
708 tsk->clear_child_tid = NULL;
713 * Allocate a new mm structure and copy contents from the
714 * mm structure of the passed in task structure.
716 struct mm_struct *dup_mm(struct task_struct *tsk)
718 struct mm_struct *mm, *oldmm = current->mm;
728 memcpy(mm, oldmm, sizeof(*mm));
731 /* Initializing for Swap token stuff */
732 mm->token_priority = 0;
733 mm->last_interval = 0;
735 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
736 mm->pmd_huge_pte = NULL;
739 if (!mm_init(mm, tsk))
742 if (init_new_context(tsk, mm))
745 dup_mm_exe_file(oldmm, mm);
747 err = dup_mmap(mm, oldmm);
751 mm->hiwater_rss = get_mm_rss(mm);
752 mm->hiwater_vm = mm->total_vm;
754 if (mm->binfmt && !try_module_get(mm->binfmt->module))
760 /* don't put binfmt in mmput, we haven't got module yet */
769 * If init_new_context() failed, we cannot use mmput() to free the mm
770 * because it calls destroy_context()
777 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
779 struct mm_struct *mm, *oldmm;
782 tsk->min_flt = tsk->maj_flt = 0;
783 tsk->nvcsw = tsk->nivcsw = 0;
784 #ifdef CONFIG_DETECT_HUNG_TASK
785 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
789 tsk->active_mm = NULL;
792 * Are we cloning a kernel thread?
794 * We need to steal a active VM for that..
800 if (clone_flags & CLONE_VM) {
801 atomic_inc(&oldmm->mm_users);
812 /* Initializing for Swap token stuff */
813 mm->token_priority = 0;
814 mm->last_interval = 0;
824 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
826 struct fs_struct *fs = current->fs;
827 if (clone_flags & CLONE_FS) {
828 /* tsk->fs is already what we want */
829 spin_lock(&fs->lock);
831 spin_unlock(&fs->lock);
835 spin_unlock(&fs->lock);
838 tsk->fs = copy_fs_struct(fs);
844 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
846 struct files_struct *oldf, *newf;
850 * A background process may not have any files ...
852 oldf = current->files;
856 if (clone_flags & CLONE_FILES) {
857 atomic_inc(&oldf->count);
861 newf = dup_fd(oldf, &error);
871 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
874 struct io_context *ioc = current->io_context;
879 * Share io context with parent, if CLONE_IO is set
881 if (clone_flags & CLONE_IO) {
882 tsk->io_context = ioc_task_link(ioc);
883 if (unlikely(!tsk->io_context))
885 } else if (ioprio_valid(ioc->ioprio)) {
886 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
887 if (unlikely(!tsk->io_context))
890 tsk->io_context->ioprio = ioc->ioprio;
896 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
898 struct sighand_struct *sig;
900 if (clone_flags & CLONE_SIGHAND) {
901 atomic_inc(¤t->sighand->count);
904 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
905 rcu_assign_pointer(tsk->sighand, sig);
908 atomic_set(&sig->count, 1);
909 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
913 void __cleanup_sighand(struct sighand_struct *sighand)
915 if (atomic_dec_and_test(&sighand->count)) {
916 signalfd_cleanup(sighand);
917 kmem_cache_free(sighand_cachep, sighand);
923 * Initialize POSIX timer handling for a thread group.
925 static void posix_cpu_timers_init_group(struct signal_struct *sig)
927 unsigned long cpu_limit;
929 /* Thread group counters. */
930 thread_group_cputime_init(sig);
932 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
933 if (cpu_limit != RLIM_INFINITY) {
934 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
935 sig->cputimer.running = 1;
938 /* The timer lists. */
939 INIT_LIST_HEAD(&sig->cpu_timers[0]);
940 INIT_LIST_HEAD(&sig->cpu_timers[1]);
941 INIT_LIST_HEAD(&sig->cpu_timers[2]);
944 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
946 struct signal_struct *sig;
948 if (clone_flags & CLONE_THREAD)
951 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
957 atomic_set(&sig->live, 1);
958 atomic_set(&sig->sigcnt, 1);
959 init_waitqueue_head(&sig->wait_chldexit);
960 if (clone_flags & CLONE_NEWPID)
961 sig->flags |= SIGNAL_UNKILLABLE;
962 sig->curr_target = tsk;
963 init_sigpending(&sig->shared_pending);
964 INIT_LIST_HEAD(&sig->posix_timers);
966 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
967 sig->real_timer.function = it_real_fn;
969 task_lock(current->group_leader);
970 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
971 task_unlock(current->group_leader);
973 posix_cpu_timers_init_group(sig);
976 sched_autogroup_fork(sig);
978 #ifdef CONFIG_CGROUPS
979 init_rwsem(&sig->threadgroup_fork_lock);
982 sig->oom_adj = current->signal->oom_adj;
983 sig->oom_score_adj = current->signal->oom_score_adj;
984 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
986 mutex_init(&sig->cred_guard_mutex);
991 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
993 unsigned long new_flags = p->flags;
995 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
996 new_flags |= PF_FORKNOEXEC;
997 new_flags |= PF_STARTING;
998 p->flags = new_flags;
999 clear_freeze_flag(p);
1002 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1004 current->clear_child_tid = tidptr;
1006 return task_pid_vnr(current);
1009 static void rt_mutex_init_task(struct task_struct *p)
1011 raw_spin_lock_init(&p->pi_lock);
1012 #ifdef CONFIG_RT_MUTEXES
1013 plist_head_init(&p->pi_waiters);
1014 p->pi_blocked_on = NULL;
1018 #ifdef CONFIG_MM_OWNER
1019 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1023 #endif /* CONFIG_MM_OWNER */
1026 * Initialize POSIX timer handling for a single task.
1028 static void posix_cpu_timers_init(struct task_struct *tsk)
1030 tsk->cputime_expires.prof_exp = cputime_zero;
1031 tsk->cputime_expires.virt_exp = cputime_zero;
1032 tsk->cputime_expires.sched_exp = 0;
1033 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1034 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1035 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1039 * This creates a new process as a copy of the old one,
1040 * but does not actually start it yet.
1042 * It copies the registers, and all the appropriate
1043 * parts of the process environment (as per the clone
1044 * flags). The actual kick-off is left to the caller.
1046 static struct task_struct *copy_process(unsigned long clone_flags,
1047 unsigned long stack_start,
1048 struct pt_regs *regs,
1049 unsigned long stack_size,
1050 int __user *child_tidptr,
1055 struct task_struct *p;
1056 int cgroup_callbacks_done = 0;
1058 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1059 return ERR_PTR(-EINVAL);
1062 * Thread groups must share signals as well, and detached threads
1063 * can only be started up within the thread group.
1065 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1066 return ERR_PTR(-EINVAL);
1069 * Shared signal handlers imply shared VM. By way of the above,
1070 * thread groups also imply shared VM. Blocking this case allows
1071 * for various simplifications in other code.
1073 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1074 return ERR_PTR(-EINVAL);
1077 * Siblings of global init remain as zombies on exit since they are
1078 * not reaped by their parent (swapper). To solve this and to avoid
1079 * multi-rooted process trees, prevent global and container-inits
1080 * from creating siblings.
1082 if ((clone_flags & CLONE_PARENT) &&
1083 current->signal->flags & SIGNAL_UNKILLABLE)
1084 return ERR_PTR(-EINVAL);
1086 retval = security_task_create(clone_flags);
1091 p = dup_task_struct(current);
1095 ftrace_graph_init_task(p);
1097 rt_mutex_init_task(p);
1099 #ifdef CONFIG_PROVE_LOCKING
1100 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1101 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1104 if (atomic_read(&p->real_cred->user->processes) >=
1105 task_rlimit(p, RLIMIT_NPROC)) {
1106 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1107 p->real_cred->user != INIT_USER)
1110 current->flags &= ~PF_NPROC_EXCEEDED;
1112 retval = copy_creds(p, clone_flags);
1117 * If multiple threads are within copy_process(), then this check
1118 * triggers too late. This doesn't hurt, the check is only there
1119 * to stop root fork bombs.
1122 if (nr_threads >= max_threads)
1123 goto bad_fork_cleanup_count;
1125 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1126 goto bad_fork_cleanup_count;
1129 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1130 copy_flags(clone_flags, p);
1131 INIT_LIST_HEAD(&p->children);
1132 INIT_LIST_HEAD(&p->sibling);
1133 rcu_copy_process(p);
1134 p->vfork_done = NULL;
1135 spin_lock_init(&p->alloc_lock);
1137 init_sigpending(&p->pending);
1139 p->utime = cputime_zero;
1140 p->stime = cputime_zero;
1141 p->gtime = cputime_zero;
1142 p->utimescaled = cputime_zero;
1143 p->stimescaled = cputime_zero;
1144 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1145 p->prev_utime = cputime_zero;
1146 p->prev_stime = cputime_zero;
1148 #if defined(SPLIT_RSS_COUNTING)
1149 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1152 p->default_timer_slack_ns = current->timer_slack_ns;
1154 task_io_accounting_init(&p->ioac);
1155 acct_clear_integrals(p);
1157 posix_cpu_timers_init(p);
1159 do_posix_clock_monotonic_gettime(&p->start_time);
1160 p->real_start_time = p->start_time;
1161 monotonic_to_bootbased(&p->real_start_time);
1162 p->io_context = NULL;
1163 p->audit_context = NULL;
1164 if (clone_flags & CLONE_THREAD)
1165 threadgroup_fork_read_lock(current);
1168 p->mempolicy = mpol_dup(p->mempolicy);
1169 if (IS_ERR(p->mempolicy)) {
1170 retval = PTR_ERR(p->mempolicy);
1171 p->mempolicy = NULL;
1172 goto bad_fork_cleanup_cgroup;
1174 mpol_fix_fork_child_flag(p);
1176 #ifdef CONFIG_CPUSETS
1177 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1178 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1180 #ifdef CONFIG_TRACE_IRQFLAGS
1182 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1183 p->hardirqs_enabled = 1;
1185 p->hardirqs_enabled = 0;
1187 p->hardirq_enable_ip = 0;
1188 p->hardirq_enable_event = 0;
1189 p->hardirq_disable_ip = _THIS_IP_;
1190 p->hardirq_disable_event = 0;
1191 p->softirqs_enabled = 1;
1192 p->softirq_enable_ip = _THIS_IP_;
1193 p->softirq_enable_event = 0;
1194 p->softirq_disable_ip = 0;
1195 p->softirq_disable_event = 0;
1196 p->hardirq_context = 0;
1197 p->softirq_context = 0;
1199 #ifdef CONFIG_LOCKDEP
1200 p->lockdep_depth = 0; /* no locks held yet */
1201 p->curr_chain_key = 0;
1202 p->lockdep_recursion = 0;
1205 #ifdef CONFIG_DEBUG_MUTEXES
1206 p->blocked_on = NULL; /* not blocked yet */
1208 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1209 p->memcg_batch.do_batch = 0;
1210 p->memcg_batch.memcg = NULL;
1213 /* Perform scheduler related setup. Assign this task to a CPU. */
1216 retval = perf_event_init_task(p);
1218 goto bad_fork_cleanup_policy;
1219 retval = audit_alloc(p);
1221 goto bad_fork_cleanup_policy;
1222 /* copy all the process information */
1223 retval = copy_semundo(clone_flags, p);
1225 goto bad_fork_cleanup_audit;
1226 retval = copy_files(clone_flags, p);
1228 goto bad_fork_cleanup_semundo;
1229 retval = copy_fs(clone_flags, p);
1231 goto bad_fork_cleanup_files;
1232 retval = copy_sighand(clone_flags, p);
1234 goto bad_fork_cleanup_fs;
1235 retval = copy_signal(clone_flags, p);
1237 goto bad_fork_cleanup_sighand;
1238 retval = copy_mm(clone_flags, p);
1240 goto bad_fork_cleanup_signal;
1241 retval = copy_namespaces(clone_flags, p);
1243 goto bad_fork_cleanup_mm;
1244 retval = copy_io(clone_flags, p);
1246 goto bad_fork_cleanup_namespaces;
1247 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1249 goto bad_fork_cleanup_io;
1251 if (pid != &init_struct_pid) {
1253 pid = alloc_pid(p->nsproxy->pid_ns);
1255 goto bad_fork_cleanup_io;
1258 p->pid = pid_nr(pid);
1260 if (clone_flags & CLONE_THREAD)
1261 p->tgid = current->tgid;
1263 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1265 * Clear TID on mm_release()?
1267 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1272 p->robust_list = NULL;
1273 #ifdef CONFIG_COMPAT
1274 p->compat_robust_list = NULL;
1276 INIT_LIST_HEAD(&p->pi_state_list);
1277 p->pi_state_cache = NULL;
1280 * sigaltstack should be cleared when sharing the same VM
1282 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1283 p->sas_ss_sp = p->sas_ss_size = 0;
1286 * Syscall tracing and stepping should be turned off in the
1287 * child regardless of CLONE_PTRACE.
1289 user_disable_single_step(p);
1290 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1291 #ifdef TIF_SYSCALL_EMU
1292 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1294 clear_all_latency_tracing(p);
1296 /* ok, now we should be set up.. */
1297 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1298 p->pdeath_signal = 0;
1302 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1305 * Ok, make it visible to the rest of the system.
1306 * We dont wake it up yet.
1308 p->group_leader = p;
1309 INIT_LIST_HEAD(&p->thread_group);
1311 /* Now that the task is set up, run cgroup callbacks if
1312 * necessary. We need to run them before the task is visible
1313 * on the tasklist. */
1314 cgroup_fork_callbacks(p);
1315 cgroup_callbacks_done = 1;
1317 /* Need tasklist lock for parent etc handling! */
1318 write_lock_irq(&tasklist_lock);
1320 /* CLONE_PARENT re-uses the old parent */
1321 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1322 p->real_parent = current->real_parent;
1323 p->parent_exec_id = current->parent_exec_id;
1325 p->real_parent = current;
1326 p->parent_exec_id = current->self_exec_id;
1329 spin_lock(¤t->sighand->siglock);
1332 * Process group and session signals need to be delivered to just the
1333 * parent before the fork or both the parent and the child after the
1334 * fork. Restart if a signal comes in before we add the new process to
1335 * it's process group.
1336 * A fatal signal pending means that current will exit, so the new
1337 * thread can't slip out of an OOM kill (or normal SIGKILL).
1339 recalc_sigpending();
1340 if (signal_pending(current)) {
1341 spin_unlock(¤t->sighand->siglock);
1342 write_unlock_irq(&tasklist_lock);
1343 retval = -ERESTARTNOINTR;
1344 goto bad_fork_free_pid;
1347 if (clone_flags & CLONE_THREAD) {
1348 current->signal->nr_threads++;
1349 atomic_inc(¤t->signal->live);
1350 atomic_inc(¤t->signal->sigcnt);
1351 p->group_leader = current->group_leader;
1352 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1355 if (likely(p->pid)) {
1356 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
1358 if (thread_group_leader(p)) {
1359 if (is_child_reaper(pid))
1360 p->nsproxy->pid_ns->child_reaper = p;
1362 p->signal->leader_pid = pid;
1363 p->signal->tty = tty_kref_get(current->signal->tty);
1364 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1365 attach_pid(p, PIDTYPE_SID, task_session(current));
1366 list_add_tail(&p->sibling, &p->real_parent->children);
1367 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1368 __this_cpu_inc(process_counts);
1370 attach_pid(p, PIDTYPE_PID, pid);
1375 spin_unlock(¤t->sighand->siglock);
1376 write_unlock_irq(&tasklist_lock);
1377 proc_fork_connector(p);
1378 cgroup_post_fork(p);
1379 if (clone_flags & CLONE_THREAD)
1380 threadgroup_fork_read_unlock(current);
1385 if (pid != &init_struct_pid)
1387 bad_fork_cleanup_io:
1390 bad_fork_cleanup_namespaces:
1391 if (unlikely(clone_flags & CLONE_NEWPID))
1392 pid_ns_release_proc(p->nsproxy->pid_ns);
1393 exit_task_namespaces(p);
1394 bad_fork_cleanup_mm:
1397 bad_fork_cleanup_signal:
1398 if (!(clone_flags & CLONE_THREAD))
1399 free_signal_struct(p->signal);
1400 bad_fork_cleanup_sighand:
1401 __cleanup_sighand(p->sighand);
1402 bad_fork_cleanup_fs:
1403 exit_fs(p); /* blocking */
1404 bad_fork_cleanup_files:
1405 exit_files(p); /* blocking */
1406 bad_fork_cleanup_semundo:
1408 bad_fork_cleanup_audit:
1410 bad_fork_cleanup_policy:
1411 perf_event_free_task(p);
1413 mpol_put(p->mempolicy);
1414 bad_fork_cleanup_cgroup:
1416 if (clone_flags & CLONE_THREAD)
1417 threadgroup_fork_read_unlock(current);
1418 cgroup_exit(p, cgroup_callbacks_done);
1419 delayacct_tsk_free(p);
1420 module_put(task_thread_info(p)->exec_domain->module);
1421 bad_fork_cleanup_count:
1422 atomic_dec(&p->cred->user->processes);
1427 return ERR_PTR(retval);
1430 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1432 memset(regs, 0, sizeof(struct pt_regs));
1436 static inline void init_idle_pids(struct pid_link *links)
1440 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1441 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1442 links[type].pid = &init_struct_pid;
1446 struct task_struct * __cpuinit fork_idle(int cpu)
1448 struct task_struct *task;
1449 struct pt_regs regs;
1451 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1452 &init_struct_pid, 0);
1453 if (!IS_ERR(task)) {
1454 init_idle_pids(task->pids);
1455 init_idle(task, cpu);
1462 * Ok, this is the main fork-routine.
1464 * It copies the process, and if successful kick-starts
1465 * it and waits for it to finish using the VM if required.
1467 long do_fork(unsigned long clone_flags,
1468 unsigned long stack_start,
1469 struct pt_regs *regs,
1470 unsigned long stack_size,
1471 int __user *parent_tidptr,
1472 int __user *child_tidptr)
1474 struct task_struct *p;
1479 * Do some preliminary argument and permissions checking before we
1480 * actually start allocating stuff
1482 if (clone_flags & CLONE_NEWUSER) {
1483 if (clone_flags & CLONE_THREAD)
1485 /* hopefully this check will go away when userns support is
1488 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1489 !capable(CAP_SETGID))
1494 * Determine whether and which event to report to ptracer. When
1495 * called from kernel_thread or CLONE_UNTRACED is explicitly
1496 * requested, no event is reported; otherwise, report if the event
1497 * for the type of forking is enabled.
1499 if (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) {
1500 if (clone_flags & CLONE_VFORK)
1501 trace = PTRACE_EVENT_VFORK;
1502 else if ((clone_flags & CSIGNAL) != SIGCHLD)
1503 trace = PTRACE_EVENT_CLONE;
1505 trace = PTRACE_EVENT_FORK;
1507 if (likely(!ptrace_event_enabled(current, trace)))
1511 p = copy_process(clone_flags, stack_start, regs, stack_size,
1512 child_tidptr, NULL, trace);
1514 * Do this prior waking up the new thread - the thread pointer
1515 * might get invalid after that point, if the thread exits quickly.
1518 struct completion vfork;
1520 trace_sched_process_fork(current, p);
1522 nr = task_pid_vnr(p);
1524 if (clone_flags & CLONE_PARENT_SETTID)
1525 put_user(nr, parent_tidptr);
1527 if (clone_flags & CLONE_VFORK) {
1528 p->vfork_done = &vfork;
1529 init_completion(&vfork);
1532 audit_finish_fork(p);
1535 * We set PF_STARTING at creation in case tracing wants to
1536 * use this to distinguish a fully live task from one that
1537 * hasn't finished SIGSTOP raising yet. Now we clear it
1538 * and set the child going.
1540 p->flags &= ~PF_STARTING;
1542 wake_up_new_task(p);
1544 /* forking complete and child started to run, tell ptracer */
1545 if (unlikely(trace))
1546 ptrace_event(trace, nr);
1548 if (clone_flags & CLONE_VFORK) {
1549 freezer_do_not_count();
1550 wait_for_completion(&vfork);
1552 ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
1560 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1561 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1564 static void sighand_ctor(void *data)
1566 struct sighand_struct *sighand = data;
1568 spin_lock_init(&sighand->siglock);
1569 init_waitqueue_head(&sighand->signalfd_wqh);
1572 void __init proc_caches_init(void)
1574 sighand_cachep = kmem_cache_create("sighand_cache",
1575 sizeof(struct sighand_struct), 0,
1576 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1577 SLAB_NOTRACK, sighand_ctor);
1578 signal_cachep = kmem_cache_create("signal_cache",
1579 sizeof(struct signal_struct), 0,
1580 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1581 files_cachep = kmem_cache_create("files_cache",
1582 sizeof(struct files_struct), 0,
1583 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1584 fs_cachep = kmem_cache_create("fs_cache",
1585 sizeof(struct fs_struct), 0,
1586 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1588 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1589 * whole struct cpumask for the OFFSTACK case. We could change
1590 * this to *only* allocate as much of it as required by the
1591 * maximum number of CPU's we can ever have. The cpumask_allocation
1592 * is at the end of the structure, exactly for that reason.
1594 mm_cachep = kmem_cache_create("mm_struct",
1595 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1596 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1597 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1599 nsproxy_cache_init();
1603 * Check constraints on flags passed to the unshare system call.
1605 static int check_unshare_flags(unsigned long unshare_flags)
1607 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1608 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1609 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1612 * Not implemented, but pretend it works if there is nothing to
1613 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1614 * needs to unshare vm.
1616 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1617 /* FIXME: get_task_mm() increments ->mm_users */
1618 if (atomic_read(¤t->mm->mm_users) > 1)
1626 * Unshare the filesystem structure if it is being shared
1628 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1630 struct fs_struct *fs = current->fs;
1632 if (!(unshare_flags & CLONE_FS) || !fs)
1635 /* don't need lock here; in the worst case we'll do useless copy */
1639 *new_fsp = copy_fs_struct(fs);
1647 * Unshare file descriptor table if it is being shared
1649 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1651 struct files_struct *fd = current->files;
1654 if ((unshare_flags & CLONE_FILES) &&
1655 (fd && atomic_read(&fd->count) > 1)) {
1656 *new_fdp = dup_fd(fd, &error);
1665 * unshare allows a process to 'unshare' part of the process
1666 * context which was originally shared using clone. copy_*
1667 * functions used by do_fork() cannot be used here directly
1668 * because they modify an inactive task_struct that is being
1669 * constructed. Here we are modifying the current, active,
1672 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1674 struct fs_struct *fs, *new_fs = NULL;
1675 struct files_struct *fd, *new_fd = NULL;
1676 struct nsproxy *new_nsproxy = NULL;
1680 err = check_unshare_flags(unshare_flags);
1682 goto bad_unshare_out;
1685 * If unsharing namespace, must also unshare filesystem information.
1687 if (unshare_flags & CLONE_NEWNS)
1688 unshare_flags |= CLONE_FS;
1690 * CLONE_NEWIPC must also detach from the undolist: after switching
1691 * to a new ipc namespace, the semaphore arrays from the old
1692 * namespace are unreachable.
1694 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1696 err = unshare_fs(unshare_flags, &new_fs);
1698 goto bad_unshare_out;
1699 err = unshare_fd(unshare_flags, &new_fd);
1701 goto bad_unshare_cleanup_fs;
1702 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs);
1704 goto bad_unshare_cleanup_fd;
1706 if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
1709 * CLONE_SYSVSEM is equivalent to sys_exit().
1715 switch_task_namespaces(current, new_nsproxy);
1723 spin_lock(&fs->lock);
1724 current->fs = new_fs;
1729 spin_unlock(&fs->lock);
1733 fd = current->files;
1734 current->files = new_fd;
1738 task_unlock(current);
1742 put_nsproxy(new_nsproxy);
1744 bad_unshare_cleanup_fd:
1746 put_files_struct(new_fd);
1748 bad_unshare_cleanup_fs:
1750 free_fs_struct(new_fs);
1757 * Helper to unshare the files of the current task.
1758 * We don't want to expose copy_files internals to
1759 * the exec layer of the kernel.
1762 int unshare_files(struct files_struct **displaced)
1764 struct task_struct *task = current;
1765 struct files_struct *copy = NULL;
1768 error = unshare_fd(CLONE_FILES, ©);
1769 if (error || !copy) {
1773 *displaced = task->files;