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/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/blkdev.h>
62 #include <linux/fs_struct.h>
63 #include <linux/magic.h>
64 #include <linux/perf_event.h>
65 #include <linux/posix-timers.h>
66 #include <linux/user-return-notifier.h>
67 #include <linux/oom.h>
68 #include <linux/khugepaged.h>
69 #include <linux/signalfd.h>
71 #include <asm/pgtable.h>
72 #include <asm/pgalloc.h>
73 #include <asm/uaccess.h>
74 #include <asm/mmu_context.h>
75 #include <asm/cacheflush.h>
76 #include <asm/tlbflush.h>
78 #include <trace/events/sched.h>
81 * Protected counters by write_lock_irq(&tasklist_lock)
83 unsigned long total_forks; /* Handle normal Linux uptimes. */
84 int nr_threads; /* The idle threads do not count.. */
86 int max_threads; /* tunable limit on nr_threads */
88 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
90 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
92 #ifdef CONFIG_PROVE_RCU
93 int lockdep_tasklist_lock_is_held(void)
95 return lockdep_is_held(&tasklist_lock);
97 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
98 #endif /* #ifdef CONFIG_PROVE_RCU */
100 int nr_processes(void)
105 for_each_possible_cpu(cpu)
106 total += per_cpu(process_counts, cpu);
111 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
112 # define alloc_task_struct_node(node) \
113 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
114 # define free_task_struct(tsk) \
115 kmem_cache_free(task_struct_cachep, (tsk))
116 static struct kmem_cache *task_struct_cachep;
119 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
120 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
123 #ifdef CONFIG_DEBUG_STACK_USAGE
124 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
126 gfp_t mask = GFP_KERNEL;
128 struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER);
130 return page ? page_address(page) : NULL;
133 static inline void free_thread_info(struct thread_info *ti)
135 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
139 /* SLAB cache for signal_struct structures (tsk->signal) */
140 static struct kmem_cache *signal_cachep;
142 /* SLAB cache for sighand_struct structures (tsk->sighand) */
143 struct kmem_cache *sighand_cachep;
145 /* SLAB cache for files_struct structures (tsk->files) */
146 struct kmem_cache *files_cachep;
148 /* SLAB cache for fs_struct structures (tsk->fs) */
149 struct kmem_cache *fs_cachep;
151 /* SLAB cache for vm_area_struct structures */
152 struct kmem_cache *vm_area_cachep;
154 /* SLAB cache for mm_struct structures (tsk->mm) */
155 static struct kmem_cache *mm_cachep;
157 static void account_kernel_stack(struct thread_info *ti, int account)
159 struct zone *zone = page_zone(virt_to_page(ti));
161 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
164 void free_task(struct task_struct *tsk)
166 account_kernel_stack(tsk->stack, -1);
167 free_thread_info(tsk->stack);
168 rt_mutex_debug_task_free(tsk);
169 ftrace_graph_exit_task(tsk);
170 free_task_struct(tsk);
172 EXPORT_SYMBOL(free_task);
174 static inline void free_signal_struct(struct signal_struct *sig)
176 taskstats_tgid_free(sig);
177 sched_autogroup_exit(sig);
178 kmem_cache_free(signal_cachep, sig);
181 static inline void put_signal_struct(struct signal_struct *sig)
183 if (atomic_dec_and_test(&sig->sigcnt))
184 free_signal_struct(sig);
187 void __put_task_struct(struct task_struct *tsk)
189 WARN_ON(!tsk->exit_state);
190 WARN_ON(atomic_read(&tsk->usage));
191 WARN_ON(tsk == current);
194 delayacct_tsk_free(tsk);
195 put_signal_struct(tsk->signal);
197 if (!profile_handoff_task(tsk))
200 EXPORT_SYMBOL_GPL(__put_task_struct);
203 * macro override instead of weak attribute alias, to workaround
204 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
206 #ifndef arch_task_cache_init
207 #define arch_task_cache_init()
210 void __init fork_init(unsigned long mempages)
212 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
213 #ifndef ARCH_MIN_TASKALIGN
214 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
216 /* create a slab on which task_structs can be allocated */
218 kmem_cache_create("task_struct", sizeof(struct task_struct),
219 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
222 /* do the arch specific task caches init */
223 arch_task_cache_init();
226 * The default maximum number of threads is set to a safe
227 * value: the thread structures can take up at most half
230 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
233 * we need to allow at least 20 threads to boot a system
235 if (max_threads < 20)
238 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
239 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
240 init_task.signal->rlim[RLIMIT_SIGPENDING] =
241 init_task.signal->rlim[RLIMIT_NPROC];
244 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
245 struct task_struct *src)
251 static struct task_struct *dup_task_struct(struct task_struct *orig)
253 struct task_struct *tsk;
254 struct thread_info *ti;
255 unsigned long *stackend;
256 int node = tsk_fork_get_node(orig);
259 prepare_to_copy(orig);
261 tsk = alloc_task_struct_node(node);
265 ti = alloc_thread_info_node(tsk, node);
267 free_task_struct(tsk);
271 err = arch_dup_task_struct(tsk, orig);
277 setup_thread_stack(tsk, orig);
278 clear_user_return_notifier(tsk);
279 clear_tsk_need_resched(tsk);
280 stackend = end_of_stack(tsk);
281 *stackend = STACK_END_MAGIC; /* for overflow detection */
283 #ifdef CONFIG_CC_STACKPROTECTOR
284 tsk->stack_canary = get_random_int();
288 * One for us, one for whoever does the "release_task()" (usually
291 atomic_set(&tsk->usage, 2);
292 #ifdef CONFIG_BLK_DEV_IO_TRACE
295 tsk->splice_pipe = NULL;
297 account_kernel_stack(ti, 1);
302 free_thread_info(ti);
303 free_task_struct(tsk);
308 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
310 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
311 struct rb_node **rb_link, *rb_parent;
313 unsigned long charge;
314 struct mempolicy *pol;
316 down_write(&oldmm->mmap_sem);
317 flush_cache_dup_mm(oldmm);
319 * Not linked in yet - no deadlock potential:
321 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
325 mm->mmap_cache = NULL;
326 mm->free_area_cache = oldmm->mmap_base;
327 mm->cached_hole_size = ~0UL;
329 cpumask_clear(mm_cpumask(mm));
331 rb_link = &mm->mm_rb.rb_node;
334 retval = ksm_fork(mm, oldmm);
337 retval = khugepaged_fork(mm, oldmm);
342 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
345 if (mpnt->vm_flags & VM_DONTCOPY) {
346 long pages = vma_pages(mpnt);
347 mm->total_vm -= pages;
348 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
353 if (mpnt->vm_flags & VM_ACCOUNT) {
354 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
355 if (security_vm_enough_memory(len))
359 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
363 INIT_LIST_HEAD(&tmp->anon_vma_chain);
364 pol = mpol_dup(vma_policy(mpnt));
365 retval = PTR_ERR(pol);
367 goto fail_nomem_policy;
368 vma_set_policy(tmp, pol);
370 if (anon_vma_fork(tmp, mpnt))
371 goto fail_nomem_anon_vma_fork;
372 tmp->vm_flags &= ~VM_LOCKED;
373 tmp->vm_next = tmp->vm_prev = NULL;
376 struct inode *inode = file->f_path.dentry->d_inode;
377 struct address_space *mapping = file->f_mapping;
380 if (tmp->vm_flags & VM_DENYWRITE)
381 atomic_dec(&inode->i_writecount);
382 mutex_lock(&mapping->i_mmap_mutex);
383 if (tmp->vm_flags & VM_SHARED)
384 mapping->i_mmap_writable++;
385 flush_dcache_mmap_lock(mapping);
386 /* insert tmp into the share list, just after mpnt */
387 vma_prio_tree_add(tmp, mpnt);
388 flush_dcache_mmap_unlock(mapping);
389 mutex_unlock(&mapping->i_mmap_mutex);
393 * Clear hugetlb-related page reserves for children. This only
394 * affects MAP_PRIVATE mappings. Faults generated by the child
395 * are not guaranteed to succeed, even if read-only
397 if (is_vm_hugetlb_page(tmp))
398 reset_vma_resv_huge_pages(tmp);
401 * Link in the new vma and copy the page table entries.
404 pprev = &tmp->vm_next;
408 __vma_link_rb(mm, tmp, rb_link, rb_parent);
409 rb_link = &tmp->vm_rb.rb_right;
410 rb_parent = &tmp->vm_rb;
413 retval = copy_page_range(mm, oldmm, mpnt);
415 if (tmp->vm_ops && tmp->vm_ops->open)
416 tmp->vm_ops->open(tmp);
421 /* a new mm has just been created */
422 arch_dup_mmap(oldmm, mm);
425 up_write(&mm->mmap_sem);
427 up_write(&oldmm->mmap_sem);
429 fail_nomem_anon_vma_fork:
432 kmem_cache_free(vm_area_cachep, tmp);
435 vm_unacct_memory(charge);
439 static inline int mm_alloc_pgd(struct mm_struct *mm)
441 mm->pgd = pgd_alloc(mm);
442 if (unlikely(!mm->pgd))
447 static inline void mm_free_pgd(struct mm_struct *mm)
449 pgd_free(mm, mm->pgd);
452 #define dup_mmap(mm, oldmm) (0)
453 #define mm_alloc_pgd(mm) (0)
454 #define mm_free_pgd(mm)
455 #endif /* CONFIG_MMU */
457 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
459 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
460 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
462 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
464 static int __init coredump_filter_setup(char *s)
466 default_dump_filter =
467 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
468 MMF_DUMP_FILTER_MASK;
472 __setup("coredump_filter=", coredump_filter_setup);
474 #include <linux/init_task.h>
476 static void mm_init_aio(struct mm_struct *mm)
479 spin_lock_init(&mm->ioctx_lock);
480 INIT_HLIST_HEAD(&mm->ioctx_list);
484 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
486 atomic_set(&mm->mm_users, 1);
487 atomic_set(&mm->mm_count, 1);
488 init_rwsem(&mm->mmap_sem);
489 INIT_LIST_HEAD(&mm->mmlist);
490 mm->flags = (current->mm) ?
491 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
492 mm->core_state = NULL;
494 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
495 spin_lock_init(&mm->page_table_lock);
496 mm->free_area_cache = TASK_UNMAPPED_BASE;
497 mm->cached_hole_size = ~0UL;
499 mm_init_owner(mm, p);
501 if (likely(!mm_alloc_pgd(mm))) {
503 mmu_notifier_mm_init(mm);
512 * Allocate and initialize an mm_struct.
514 struct mm_struct *mm_alloc(void)
516 struct mm_struct *mm;
522 memset(mm, 0, sizeof(*mm));
524 return mm_init(mm, current);
528 * Called when the last reference to the mm
529 * is dropped: either by a lazy thread or by
530 * mmput. Free the page directory and the mm.
532 void __mmdrop(struct mm_struct *mm)
534 BUG_ON(mm == &init_mm);
537 mmu_notifier_mm_destroy(mm);
538 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
539 VM_BUG_ON(mm->pmd_huge_pte);
543 EXPORT_SYMBOL_GPL(__mmdrop);
546 * Decrement the use count and release all resources for an mm.
548 void mmput(struct mm_struct *mm)
552 if (atomic_dec_and_test(&mm->mm_users)) {
555 khugepaged_exit(mm); /* must run before exit_mmap */
557 set_mm_exe_file(mm, NULL);
558 if (!list_empty(&mm->mmlist)) {
559 spin_lock(&mmlist_lock);
560 list_del(&mm->mmlist);
561 spin_unlock(&mmlist_lock);
565 module_put(mm->binfmt->module);
569 EXPORT_SYMBOL_GPL(mmput);
572 * We added or removed a vma mapping the executable. The vmas are only mapped
573 * during exec and are not mapped with the mmap system call.
574 * Callers must hold down_write() on the mm's mmap_sem for these
576 void added_exe_file_vma(struct mm_struct *mm)
578 mm->num_exe_file_vmas++;
581 void removed_exe_file_vma(struct mm_struct *mm)
583 mm->num_exe_file_vmas--;
584 if ((mm->num_exe_file_vmas == 0) && mm->exe_file) {
591 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
594 get_file(new_exe_file);
597 mm->exe_file = new_exe_file;
598 mm->num_exe_file_vmas = 0;
601 struct file *get_mm_exe_file(struct mm_struct *mm)
603 struct file *exe_file;
605 /* We need mmap_sem to protect against races with removal of
606 * VM_EXECUTABLE vmas */
607 down_read(&mm->mmap_sem);
608 exe_file = mm->exe_file;
611 up_read(&mm->mmap_sem);
615 static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
617 /* It's safe to write the exe_file pointer without exe_file_lock because
618 * this is called during fork when the task is not yet in /proc */
619 newmm->exe_file = get_mm_exe_file(oldmm);
623 * get_task_mm - acquire a reference to the task's mm
625 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
626 * this kernel workthread has transiently adopted a user mm with use_mm,
627 * to do its AIO) is not set and if so returns a reference to it, after
628 * bumping up the use count. User must release the mm via mmput()
629 * after use. Typically used by /proc and ptrace.
631 struct mm_struct *get_task_mm(struct task_struct *task)
633 struct mm_struct *mm;
638 if (task->flags & PF_KTHREAD)
641 atomic_inc(&mm->mm_users);
646 EXPORT_SYMBOL_GPL(get_task_mm);
648 /* Please note the differences between mmput and mm_release.
649 * mmput is called whenever we stop holding onto a mm_struct,
650 * error success whatever.
652 * mm_release is called after a mm_struct has been removed
653 * from the current process.
655 * This difference is important for error handling, when we
656 * only half set up a mm_struct for a new process and need to restore
657 * the old one. Because we mmput the new mm_struct before
658 * restoring the old one. . .
659 * Eric Biederman 10 January 1998
661 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
663 struct completion *vfork_done = tsk->vfork_done;
665 /* Get rid of any futexes when releasing the mm */
667 if (unlikely(tsk->robust_list)) {
668 exit_robust_list(tsk);
669 tsk->robust_list = NULL;
672 if (unlikely(tsk->compat_robust_list)) {
673 compat_exit_robust_list(tsk);
674 tsk->compat_robust_list = NULL;
677 if (unlikely(!list_empty(&tsk->pi_state_list)))
678 exit_pi_state_list(tsk);
681 /* Get rid of any cached register state */
682 deactivate_mm(tsk, mm);
684 /* notify parent sleeping on vfork() */
686 tsk->vfork_done = NULL;
687 complete(vfork_done);
691 * If we're exiting normally, clear a user-space tid field if
692 * requested. We leave this alone when dying by signal, to leave
693 * the value intact in a core dump, and to save the unnecessary
694 * trouble otherwise. Userland only wants this done for a sys_exit.
696 if (tsk->clear_child_tid) {
697 if (!(tsk->flags & PF_SIGNALED) &&
698 atomic_read(&mm->mm_users) > 1) {
700 * We don't check the error code - if userspace has
701 * not set up a proper pointer then tough luck.
703 put_user(0, tsk->clear_child_tid);
704 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
707 tsk->clear_child_tid = NULL;
712 * Allocate a new mm structure and copy contents from the
713 * mm structure of the passed in task structure.
715 struct mm_struct *dup_mm(struct task_struct *tsk)
717 struct mm_struct *mm, *oldmm = current->mm;
727 memcpy(mm, oldmm, sizeof(*mm));
730 /* Initializing for Swap token stuff */
731 mm->token_priority = 0;
732 mm->last_interval = 0;
734 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
735 mm->pmd_huge_pte = NULL;
738 if (!mm_init(mm, tsk))
741 if (init_new_context(tsk, mm))
744 dup_mm_exe_file(oldmm, mm);
746 err = dup_mmap(mm, oldmm);
750 mm->hiwater_rss = get_mm_rss(mm);
751 mm->hiwater_vm = mm->total_vm;
753 if (mm->binfmt && !try_module_get(mm->binfmt->module))
759 /* don't put binfmt in mmput, we haven't got module yet */
768 * If init_new_context() failed, we cannot use mmput() to free the mm
769 * because it calls destroy_context()
776 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
778 struct mm_struct *mm, *oldmm;
781 tsk->min_flt = tsk->maj_flt = 0;
782 tsk->nvcsw = tsk->nivcsw = 0;
783 #ifdef CONFIG_DETECT_HUNG_TASK
784 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
788 tsk->active_mm = NULL;
791 * Are we cloning a kernel thread?
793 * We need to steal a active VM for that..
799 if (clone_flags & CLONE_VM) {
800 atomic_inc(&oldmm->mm_users);
811 /* Initializing for Swap token stuff */
812 mm->token_priority = 0;
813 mm->last_interval = 0;
823 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
825 struct fs_struct *fs = current->fs;
826 if (clone_flags & CLONE_FS) {
827 /* tsk->fs is already what we want */
828 spin_lock(&fs->lock);
830 spin_unlock(&fs->lock);
834 spin_unlock(&fs->lock);
837 tsk->fs = copy_fs_struct(fs);
843 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
845 struct files_struct *oldf, *newf;
849 * A background process may not have any files ...
851 oldf = current->files;
855 if (clone_flags & CLONE_FILES) {
856 atomic_inc(&oldf->count);
860 newf = dup_fd(oldf, &error);
870 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
873 struct io_context *ioc = current->io_context;
878 * Share io context with parent, if CLONE_IO is set
880 if (clone_flags & CLONE_IO) {
881 tsk->io_context = ioc_task_link(ioc);
882 if (unlikely(!tsk->io_context))
884 } else if (ioprio_valid(ioc->ioprio)) {
885 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
886 if (unlikely(!tsk->io_context))
889 tsk->io_context->ioprio = ioc->ioprio;
895 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
897 struct sighand_struct *sig;
899 if (clone_flags & CLONE_SIGHAND) {
900 atomic_inc(¤t->sighand->count);
903 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
904 rcu_assign_pointer(tsk->sighand, sig);
907 atomic_set(&sig->count, 1);
908 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
912 void __cleanup_sighand(struct sighand_struct *sighand)
914 if (atomic_dec_and_test(&sighand->count)) {
915 signalfd_cleanup(sighand);
916 kmem_cache_free(sighand_cachep, sighand);
922 * Initialize POSIX timer handling for a thread group.
924 static void posix_cpu_timers_init_group(struct signal_struct *sig)
926 unsigned long cpu_limit;
928 /* Thread group counters. */
929 thread_group_cputime_init(sig);
931 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
932 if (cpu_limit != RLIM_INFINITY) {
933 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
934 sig->cputimer.running = 1;
937 /* The timer lists. */
938 INIT_LIST_HEAD(&sig->cpu_timers[0]);
939 INIT_LIST_HEAD(&sig->cpu_timers[1]);
940 INIT_LIST_HEAD(&sig->cpu_timers[2]);
943 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
945 struct signal_struct *sig;
947 if (clone_flags & CLONE_THREAD)
950 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
956 atomic_set(&sig->live, 1);
957 atomic_set(&sig->sigcnt, 1);
958 init_waitqueue_head(&sig->wait_chldexit);
959 if (clone_flags & CLONE_NEWPID)
960 sig->flags |= SIGNAL_UNKILLABLE;
961 sig->curr_target = tsk;
962 init_sigpending(&sig->shared_pending);
963 INIT_LIST_HEAD(&sig->posix_timers);
965 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
966 sig->real_timer.function = it_real_fn;
968 task_lock(current->group_leader);
969 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
970 task_unlock(current->group_leader);
972 posix_cpu_timers_init_group(sig);
975 sched_autogroup_fork(sig);
977 #ifdef CONFIG_CGROUPS
978 init_rwsem(&sig->threadgroup_fork_lock);
981 sig->oom_adj = current->signal->oom_adj;
982 sig->oom_score_adj = current->signal->oom_score_adj;
983 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
985 mutex_init(&sig->cred_guard_mutex);
990 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
992 unsigned long new_flags = p->flags;
994 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
995 new_flags |= PF_FORKNOEXEC;
996 new_flags |= PF_STARTING;
997 p->flags = new_flags;
998 clear_freeze_flag(p);
1001 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1003 current->clear_child_tid = tidptr;
1005 return task_pid_vnr(current);
1008 static void rt_mutex_init_task(struct task_struct *p)
1010 raw_spin_lock_init(&p->pi_lock);
1011 #ifdef CONFIG_RT_MUTEXES
1012 plist_head_init(&p->pi_waiters);
1013 p->pi_blocked_on = NULL;
1017 #ifdef CONFIG_MM_OWNER
1018 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1022 #endif /* CONFIG_MM_OWNER */
1025 * Initialize POSIX timer handling for a single task.
1027 static void posix_cpu_timers_init(struct task_struct *tsk)
1029 tsk->cputime_expires.prof_exp = cputime_zero;
1030 tsk->cputime_expires.virt_exp = cputime_zero;
1031 tsk->cputime_expires.sched_exp = 0;
1032 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1033 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1034 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1038 * This creates a new process as a copy of the old one,
1039 * but does not actually start it yet.
1041 * It copies the registers, and all the appropriate
1042 * parts of the process environment (as per the clone
1043 * flags). The actual kick-off is left to the caller.
1045 static struct task_struct *copy_process(unsigned long clone_flags,
1046 unsigned long stack_start,
1047 struct pt_regs *regs,
1048 unsigned long stack_size,
1049 int __user *child_tidptr,
1054 struct task_struct *p;
1055 int cgroup_callbacks_done = 0;
1057 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1058 return ERR_PTR(-EINVAL);
1061 * Thread groups must share signals as well, and detached threads
1062 * can only be started up within the thread group.
1064 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1065 return ERR_PTR(-EINVAL);
1068 * Shared signal handlers imply shared VM. By way of the above,
1069 * thread groups also imply shared VM. Blocking this case allows
1070 * for various simplifications in other code.
1072 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1073 return ERR_PTR(-EINVAL);
1076 * Siblings of global init remain as zombies on exit since they are
1077 * not reaped by their parent (swapper). To solve this and to avoid
1078 * multi-rooted process trees, prevent global and container-inits
1079 * from creating siblings.
1081 if ((clone_flags & CLONE_PARENT) &&
1082 current->signal->flags & SIGNAL_UNKILLABLE)
1083 return ERR_PTR(-EINVAL);
1085 retval = security_task_create(clone_flags);
1090 p = dup_task_struct(current);
1094 ftrace_graph_init_task(p);
1096 rt_mutex_init_task(p);
1098 #ifdef CONFIG_PROVE_LOCKING
1099 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1100 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1103 if (atomic_read(&p->real_cred->user->processes) >=
1104 task_rlimit(p, RLIMIT_NPROC)) {
1105 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1106 p->real_cred->user != INIT_USER)
1109 current->flags &= ~PF_NPROC_EXCEEDED;
1111 retval = copy_creds(p, clone_flags);
1116 * If multiple threads are within copy_process(), then this check
1117 * triggers too late. This doesn't hurt, the check is only there
1118 * to stop root fork bombs.
1121 if (nr_threads >= max_threads)
1122 goto bad_fork_cleanup_count;
1124 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1125 goto bad_fork_cleanup_count;
1128 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1129 copy_flags(clone_flags, p);
1130 INIT_LIST_HEAD(&p->children);
1131 INIT_LIST_HEAD(&p->sibling);
1132 rcu_copy_process(p);
1133 p->vfork_done = NULL;
1134 spin_lock_init(&p->alloc_lock);
1136 init_sigpending(&p->pending);
1138 p->utime = cputime_zero;
1139 p->stime = cputime_zero;
1140 p->gtime = cputime_zero;
1141 p->utimescaled = cputime_zero;
1142 p->stimescaled = cputime_zero;
1143 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1144 p->prev_utime = cputime_zero;
1145 p->prev_stime = cputime_zero;
1147 #if defined(SPLIT_RSS_COUNTING)
1148 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1151 p->default_timer_slack_ns = current->timer_slack_ns;
1153 task_io_accounting_init(&p->ioac);
1154 acct_clear_integrals(p);
1156 posix_cpu_timers_init(p);
1158 do_posix_clock_monotonic_gettime(&p->start_time);
1159 p->real_start_time = p->start_time;
1160 monotonic_to_bootbased(&p->real_start_time);
1161 p->io_context = NULL;
1162 p->audit_context = NULL;
1163 if (clone_flags & CLONE_THREAD)
1164 threadgroup_fork_read_lock(current);
1167 p->mempolicy = mpol_dup(p->mempolicy);
1168 if (IS_ERR(p->mempolicy)) {
1169 retval = PTR_ERR(p->mempolicy);
1170 p->mempolicy = NULL;
1171 goto bad_fork_cleanup_cgroup;
1173 mpol_fix_fork_child_flag(p);
1175 #ifdef CONFIG_CPUSETS
1176 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1177 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1179 #ifdef CONFIG_TRACE_IRQFLAGS
1181 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1182 p->hardirqs_enabled = 1;
1184 p->hardirqs_enabled = 0;
1186 p->hardirq_enable_ip = 0;
1187 p->hardirq_enable_event = 0;
1188 p->hardirq_disable_ip = _THIS_IP_;
1189 p->hardirq_disable_event = 0;
1190 p->softirqs_enabled = 1;
1191 p->softirq_enable_ip = _THIS_IP_;
1192 p->softirq_enable_event = 0;
1193 p->softirq_disable_ip = 0;
1194 p->softirq_disable_event = 0;
1195 p->hardirq_context = 0;
1196 p->softirq_context = 0;
1198 #ifdef CONFIG_LOCKDEP
1199 p->lockdep_depth = 0; /* no locks held yet */
1200 p->curr_chain_key = 0;
1201 p->lockdep_recursion = 0;
1204 #ifdef CONFIG_DEBUG_MUTEXES
1205 p->blocked_on = NULL; /* not blocked yet */
1207 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1208 p->memcg_batch.do_batch = 0;
1209 p->memcg_batch.memcg = NULL;
1212 /* Perform scheduler related setup. Assign this task to a CPU. */
1215 retval = perf_event_init_task(p);
1217 goto bad_fork_cleanup_policy;
1218 retval = audit_alloc(p);
1220 goto bad_fork_cleanup_policy;
1221 /* copy all the process information */
1222 retval = copy_semundo(clone_flags, p);
1224 goto bad_fork_cleanup_audit;
1225 retval = copy_files(clone_flags, p);
1227 goto bad_fork_cleanup_semundo;
1228 retval = copy_fs(clone_flags, p);
1230 goto bad_fork_cleanup_files;
1231 retval = copy_sighand(clone_flags, p);
1233 goto bad_fork_cleanup_fs;
1234 retval = copy_signal(clone_flags, p);
1236 goto bad_fork_cleanup_sighand;
1237 retval = copy_mm(clone_flags, p);
1239 goto bad_fork_cleanup_signal;
1240 retval = copy_namespaces(clone_flags, p);
1242 goto bad_fork_cleanup_mm;
1243 retval = copy_io(clone_flags, p);
1245 goto bad_fork_cleanup_namespaces;
1246 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1248 goto bad_fork_cleanup_io;
1250 if (pid != &init_struct_pid) {
1252 pid = alloc_pid(p->nsproxy->pid_ns);
1254 goto bad_fork_cleanup_io;
1257 p->pid = pid_nr(pid);
1259 if (clone_flags & CLONE_THREAD)
1260 p->tgid = current->tgid;
1262 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1264 * Clear TID on mm_release()?
1266 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1271 p->robust_list = NULL;
1272 #ifdef CONFIG_COMPAT
1273 p->compat_robust_list = NULL;
1275 INIT_LIST_HEAD(&p->pi_state_list);
1276 p->pi_state_cache = NULL;
1279 * sigaltstack should be cleared when sharing the same VM
1281 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1282 p->sas_ss_sp = p->sas_ss_size = 0;
1285 * Syscall tracing and stepping should be turned off in the
1286 * child regardless of CLONE_PTRACE.
1288 user_disable_single_step(p);
1289 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1290 #ifdef TIF_SYSCALL_EMU
1291 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1293 clear_all_latency_tracing(p);
1295 /* ok, now we should be set up.. */
1296 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1297 p->pdeath_signal = 0;
1301 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1304 * Ok, make it visible to the rest of the system.
1305 * We dont wake it up yet.
1307 p->group_leader = p;
1308 INIT_LIST_HEAD(&p->thread_group);
1310 /* Now that the task is set up, run cgroup callbacks if
1311 * necessary. We need to run them before the task is visible
1312 * on the tasklist. */
1313 cgroup_fork_callbacks(p);
1314 cgroup_callbacks_done = 1;
1316 /* Need tasklist lock for parent etc handling! */
1317 write_lock_irq(&tasklist_lock);
1319 /* CLONE_PARENT re-uses the old parent */
1320 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1321 p->real_parent = current->real_parent;
1322 p->parent_exec_id = current->parent_exec_id;
1324 p->real_parent = current;
1325 p->parent_exec_id = current->self_exec_id;
1328 spin_lock(¤t->sighand->siglock);
1331 * Process group and session signals need to be delivered to just the
1332 * parent before the fork or both the parent and the child after the
1333 * fork. Restart if a signal comes in before we add the new process to
1334 * it's process group.
1335 * A fatal signal pending means that current will exit, so the new
1336 * thread can't slip out of an OOM kill (or normal SIGKILL).
1338 recalc_sigpending();
1339 if (signal_pending(current)) {
1340 spin_unlock(¤t->sighand->siglock);
1341 write_unlock_irq(&tasklist_lock);
1342 retval = -ERESTARTNOINTR;
1343 goto bad_fork_free_pid;
1346 if (clone_flags & CLONE_THREAD) {
1347 current->signal->nr_threads++;
1348 atomic_inc(¤t->signal->live);
1349 atomic_inc(¤t->signal->sigcnt);
1350 p->group_leader = current->group_leader;
1351 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1354 if (likely(p->pid)) {
1355 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
1357 if (thread_group_leader(p)) {
1358 if (is_child_reaper(pid))
1359 p->nsproxy->pid_ns->child_reaper = p;
1361 p->signal->leader_pid = pid;
1362 p->signal->tty = tty_kref_get(current->signal->tty);
1363 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1364 attach_pid(p, PIDTYPE_SID, task_session(current));
1365 list_add_tail(&p->sibling, &p->real_parent->children);
1366 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1367 __this_cpu_inc(process_counts);
1369 attach_pid(p, PIDTYPE_PID, pid);
1374 spin_unlock(¤t->sighand->siglock);
1375 write_unlock_irq(&tasklist_lock);
1376 proc_fork_connector(p);
1377 cgroup_post_fork(p);
1378 if (clone_flags & CLONE_THREAD)
1379 threadgroup_fork_read_unlock(current);
1384 if (pid != &init_struct_pid)
1386 bad_fork_cleanup_io:
1389 bad_fork_cleanup_namespaces:
1390 exit_task_namespaces(p);
1391 bad_fork_cleanup_mm:
1394 bad_fork_cleanup_signal:
1395 if (!(clone_flags & CLONE_THREAD))
1396 free_signal_struct(p->signal);
1397 bad_fork_cleanup_sighand:
1398 __cleanup_sighand(p->sighand);
1399 bad_fork_cleanup_fs:
1400 exit_fs(p); /* blocking */
1401 bad_fork_cleanup_files:
1402 exit_files(p); /* blocking */
1403 bad_fork_cleanup_semundo:
1405 bad_fork_cleanup_audit:
1407 bad_fork_cleanup_policy:
1408 perf_event_free_task(p);
1410 mpol_put(p->mempolicy);
1411 bad_fork_cleanup_cgroup:
1413 if (clone_flags & CLONE_THREAD)
1414 threadgroup_fork_read_unlock(current);
1415 cgroup_exit(p, cgroup_callbacks_done);
1416 delayacct_tsk_free(p);
1417 module_put(task_thread_info(p)->exec_domain->module);
1418 bad_fork_cleanup_count:
1419 atomic_dec(&p->cred->user->processes);
1424 return ERR_PTR(retval);
1427 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1429 memset(regs, 0, sizeof(struct pt_regs));
1433 static inline void init_idle_pids(struct pid_link *links)
1437 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1438 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1439 links[type].pid = &init_struct_pid;
1443 struct task_struct * __cpuinit fork_idle(int cpu)
1445 struct task_struct *task;
1446 struct pt_regs regs;
1448 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1449 &init_struct_pid, 0);
1450 if (!IS_ERR(task)) {
1451 init_idle_pids(task->pids);
1452 init_idle(task, cpu);
1459 * Ok, this is the main fork-routine.
1461 * It copies the process, and if successful kick-starts
1462 * it and waits for it to finish using the VM if required.
1464 long do_fork(unsigned long clone_flags,
1465 unsigned long stack_start,
1466 struct pt_regs *regs,
1467 unsigned long stack_size,
1468 int __user *parent_tidptr,
1469 int __user *child_tidptr)
1471 struct task_struct *p;
1476 * Do some preliminary argument and permissions checking before we
1477 * actually start allocating stuff
1479 if (clone_flags & CLONE_NEWUSER) {
1480 if (clone_flags & CLONE_THREAD)
1482 /* hopefully this check will go away when userns support is
1485 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1486 !capable(CAP_SETGID))
1491 * Determine whether and which event to report to ptracer. When
1492 * called from kernel_thread or CLONE_UNTRACED is explicitly
1493 * requested, no event is reported; otherwise, report if the event
1494 * for the type of forking is enabled.
1496 if (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) {
1497 if (clone_flags & CLONE_VFORK)
1498 trace = PTRACE_EVENT_VFORK;
1499 else if ((clone_flags & CSIGNAL) != SIGCHLD)
1500 trace = PTRACE_EVENT_CLONE;
1502 trace = PTRACE_EVENT_FORK;
1504 if (likely(!ptrace_event_enabled(current, trace)))
1508 p = copy_process(clone_flags, stack_start, regs, stack_size,
1509 child_tidptr, NULL, trace);
1511 * Do this prior waking up the new thread - the thread pointer
1512 * might get invalid after that point, if the thread exits quickly.
1515 struct completion vfork;
1517 trace_sched_process_fork(current, p);
1519 nr = task_pid_vnr(p);
1521 if (clone_flags & CLONE_PARENT_SETTID)
1522 put_user(nr, parent_tidptr);
1524 if (clone_flags & CLONE_VFORK) {
1525 p->vfork_done = &vfork;
1526 init_completion(&vfork);
1529 audit_finish_fork(p);
1532 * We set PF_STARTING at creation in case tracing wants to
1533 * use this to distinguish a fully live task from one that
1534 * hasn't finished SIGSTOP raising yet. Now we clear it
1535 * and set the child going.
1537 p->flags &= ~PF_STARTING;
1539 wake_up_new_task(p);
1541 /* forking complete and child started to run, tell ptracer */
1542 if (unlikely(trace))
1543 ptrace_event(trace, nr);
1545 if (clone_flags & CLONE_VFORK) {
1546 freezer_do_not_count();
1547 wait_for_completion(&vfork);
1549 ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
1557 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1558 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1561 static void sighand_ctor(void *data)
1563 struct sighand_struct *sighand = data;
1565 spin_lock_init(&sighand->siglock);
1566 init_waitqueue_head(&sighand->signalfd_wqh);
1569 void __init proc_caches_init(void)
1571 sighand_cachep = kmem_cache_create("sighand_cache",
1572 sizeof(struct sighand_struct), 0,
1573 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1574 SLAB_NOTRACK, sighand_ctor);
1575 signal_cachep = kmem_cache_create("signal_cache",
1576 sizeof(struct signal_struct), 0,
1577 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1578 files_cachep = kmem_cache_create("files_cache",
1579 sizeof(struct files_struct), 0,
1580 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1581 fs_cachep = kmem_cache_create("fs_cache",
1582 sizeof(struct fs_struct), 0,
1583 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1585 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1586 * whole struct cpumask for the OFFSTACK case. We could change
1587 * this to *only* allocate as much of it as required by the
1588 * maximum number of CPU's we can ever have. The cpumask_allocation
1589 * is at the end of the structure, exactly for that reason.
1591 mm_cachep = kmem_cache_create("mm_struct",
1592 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1593 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1594 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1596 nsproxy_cache_init();
1600 * Check constraints on flags passed to the unshare system call.
1602 static int check_unshare_flags(unsigned long unshare_flags)
1604 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1605 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1606 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1609 * Not implemented, but pretend it works if there is nothing to
1610 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1611 * needs to unshare vm.
1613 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1614 /* FIXME: get_task_mm() increments ->mm_users */
1615 if (atomic_read(¤t->mm->mm_users) > 1)
1623 * Unshare the filesystem structure if it is being shared
1625 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1627 struct fs_struct *fs = current->fs;
1629 if (!(unshare_flags & CLONE_FS) || !fs)
1632 /* don't need lock here; in the worst case we'll do useless copy */
1636 *new_fsp = copy_fs_struct(fs);
1644 * Unshare file descriptor table if it is being shared
1646 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1648 struct files_struct *fd = current->files;
1651 if ((unshare_flags & CLONE_FILES) &&
1652 (fd && atomic_read(&fd->count) > 1)) {
1653 *new_fdp = dup_fd(fd, &error);
1662 * unshare allows a process to 'unshare' part of the process
1663 * context which was originally shared using clone. copy_*
1664 * functions used by do_fork() cannot be used here directly
1665 * because they modify an inactive task_struct that is being
1666 * constructed. Here we are modifying the current, active,
1669 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1671 struct fs_struct *fs, *new_fs = NULL;
1672 struct files_struct *fd, *new_fd = NULL;
1673 struct nsproxy *new_nsproxy = NULL;
1677 err = check_unshare_flags(unshare_flags);
1679 goto bad_unshare_out;
1682 * If unsharing namespace, must also unshare filesystem information.
1684 if (unshare_flags & CLONE_NEWNS)
1685 unshare_flags |= CLONE_FS;
1687 * CLONE_NEWIPC must also detach from the undolist: after switching
1688 * to a new ipc namespace, the semaphore arrays from the old
1689 * namespace are unreachable.
1691 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1693 err = unshare_fs(unshare_flags, &new_fs);
1695 goto bad_unshare_out;
1696 err = unshare_fd(unshare_flags, &new_fd);
1698 goto bad_unshare_cleanup_fs;
1699 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs);
1701 goto bad_unshare_cleanup_fd;
1703 if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
1706 * CLONE_SYSVSEM is equivalent to sys_exit().
1712 switch_task_namespaces(current, new_nsproxy);
1720 spin_lock(&fs->lock);
1721 current->fs = new_fs;
1726 spin_unlock(&fs->lock);
1730 fd = current->files;
1731 current->files = new_fd;
1735 task_unlock(current);
1739 put_nsproxy(new_nsproxy);
1741 bad_unshare_cleanup_fd:
1743 put_files_struct(new_fd);
1745 bad_unshare_cleanup_fs:
1747 free_fs_struct(new_fs);
1754 * Helper to unshare the files of the current task.
1755 * We don't want to expose copy_files internals to
1756 * the exec layer of the kernel.
1759 int unshare_files(struct files_struct **displaced)
1761 struct task_struct *task = current;
1762 struct files_struct *copy = NULL;
1765 error = unshare_fd(CLONE_FILES, ©);
1766 if (error || !copy) {
1770 *displaced = task->files;