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/kthread.h>
44 #include <linux/task_io_accounting_ops.h>
45 #include <linux/rcupdate.h>
46 #include <linux/ptrace.h>
47 #include <linux/mount.h>
48 #include <linux/audit.h>
49 #include <linux/memcontrol.h>
50 #include <linux/ftrace.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>
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 /* Notifier list called when a task struct is freed */
158 static ATOMIC_NOTIFIER_HEAD(task_free_notifier);
160 static void account_kernel_stack(struct thread_info *ti, int account)
162 struct zone *zone = page_zone(virt_to_page(ti));
164 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
167 void free_task(struct task_struct *tsk)
169 prop_local_destroy_single(&tsk->dirties);
170 account_kernel_stack(tsk->stack, -1);
171 free_thread_info(tsk->stack);
172 rt_mutex_debug_task_free(tsk);
173 ftrace_graph_exit_task(tsk);
174 free_task_struct(tsk);
176 EXPORT_SYMBOL(free_task);
178 static inline void free_signal_struct(struct signal_struct *sig)
180 taskstats_tgid_free(sig);
181 sched_autogroup_exit(sig);
182 kmem_cache_free(signal_cachep, sig);
185 static inline void put_signal_struct(struct signal_struct *sig)
187 if (atomic_dec_and_test(&sig->sigcnt))
188 free_signal_struct(sig);
191 int task_free_register(struct notifier_block *n)
193 return atomic_notifier_chain_register(&task_free_notifier, n);
195 EXPORT_SYMBOL(task_free_register);
197 int task_free_unregister(struct notifier_block *n)
199 return atomic_notifier_chain_unregister(&task_free_notifier, n);
201 EXPORT_SYMBOL(task_free_unregister);
203 void __put_task_struct(struct task_struct *tsk)
205 WARN_ON(!tsk->exit_state);
206 WARN_ON(atomic_read(&tsk->usage));
207 WARN_ON(tsk == current);
210 delayacct_tsk_free(tsk);
211 put_signal_struct(tsk->signal);
213 atomic_notifier_call_chain(&task_free_notifier, 0, tsk);
214 if (!profile_handoff_task(tsk))
217 EXPORT_SYMBOL_GPL(__put_task_struct);
220 * macro override instead of weak attribute alias, to workaround
221 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
223 #ifndef arch_task_cache_init
224 #define arch_task_cache_init()
227 void __init fork_init(unsigned long mempages)
229 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
230 #ifndef ARCH_MIN_TASKALIGN
231 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
233 /* create a slab on which task_structs can be allocated */
235 kmem_cache_create("task_struct", sizeof(struct task_struct),
236 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
239 /* do the arch specific task caches init */
240 arch_task_cache_init();
243 * The default maximum number of threads is set to a safe
244 * value: the thread structures can take up at most half
247 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
250 * we need to allow at least 20 threads to boot a system
255 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
256 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
257 init_task.signal->rlim[RLIMIT_SIGPENDING] =
258 init_task.signal->rlim[RLIMIT_NPROC];
261 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
262 struct task_struct *src)
268 static struct task_struct *dup_task_struct(struct task_struct *orig)
270 struct task_struct *tsk;
271 struct thread_info *ti;
272 unsigned long *stackend;
273 int node = tsk_fork_get_node(orig);
276 prepare_to_copy(orig);
278 tsk = alloc_task_struct_node(node);
282 ti = alloc_thread_info_node(tsk, node);
284 free_task_struct(tsk);
288 err = arch_dup_task_struct(tsk, orig);
294 err = prop_local_init_single(&tsk->dirties);
298 setup_thread_stack(tsk, orig);
299 clear_user_return_notifier(tsk);
300 clear_tsk_need_resched(tsk);
301 stackend = end_of_stack(tsk);
302 *stackend = STACK_END_MAGIC; /* for overflow detection */
304 #ifdef CONFIG_CC_STACKPROTECTOR
305 tsk->stack_canary = get_random_int();
308 /* One for us, one for whoever does the "release_task()" (usually parent) */
309 atomic_set(&tsk->usage,2);
310 atomic_set(&tsk->fs_excl, 0);
311 #ifdef CONFIG_BLK_DEV_IO_TRACE
314 tsk->splice_pipe = NULL;
316 account_kernel_stack(ti, 1);
321 free_thread_info(ti);
322 free_task_struct(tsk);
327 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
329 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
330 struct rb_node **rb_link, *rb_parent;
332 unsigned long charge;
333 struct mempolicy *pol;
335 down_write(&oldmm->mmap_sem);
336 flush_cache_dup_mm(oldmm);
338 * Not linked in yet - no deadlock potential:
340 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
344 mm->mmap_cache = NULL;
345 mm->free_area_cache = oldmm->mmap_base;
346 mm->cached_hole_size = ~0UL;
348 cpumask_clear(mm_cpumask(mm));
350 rb_link = &mm->mm_rb.rb_node;
353 retval = ksm_fork(mm, oldmm);
356 retval = khugepaged_fork(mm, oldmm);
361 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
364 if (mpnt->vm_flags & VM_DONTCOPY) {
365 long pages = vma_pages(mpnt);
366 mm->total_vm -= pages;
367 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
372 if (mpnt->vm_flags & VM_ACCOUNT) {
373 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
374 if (security_vm_enough_memory(len))
378 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
382 INIT_LIST_HEAD(&tmp->anon_vma_chain);
383 pol = mpol_dup(vma_policy(mpnt));
384 retval = PTR_ERR(pol);
386 goto fail_nomem_policy;
387 vma_set_policy(tmp, pol);
389 if (anon_vma_fork(tmp, mpnt))
390 goto fail_nomem_anon_vma_fork;
391 tmp->vm_flags &= ~VM_LOCKED;
392 tmp->vm_next = tmp->vm_prev = NULL;
395 struct inode *inode = file->f_path.dentry->d_inode;
396 struct address_space *mapping = file->f_mapping;
399 if (tmp->vm_flags & VM_DENYWRITE)
400 atomic_dec(&inode->i_writecount);
401 mutex_lock(&mapping->i_mmap_mutex);
402 if (tmp->vm_flags & VM_SHARED)
403 mapping->i_mmap_writable++;
404 flush_dcache_mmap_lock(mapping);
405 /* insert tmp into the share list, just after mpnt */
406 vma_prio_tree_add(tmp, mpnt);
407 flush_dcache_mmap_unlock(mapping);
408 mutex_unlock(&mapping->i_mmap_mutex);
412 * Clear hugetlb-related page reserves for children. This only
413 * affects MAP_PRIVATE mappings. Faults generated by the child
414 * are not guaranteed to succeed, even if read-only
416 if (is_vm_hugetlb_page(tmp))
417 reset_vma_resv_huge_pages(tmp);
420 * Link in the new vma and copy the page table entries.
423 pprev = &tmp->vm_next;
427 __vma_link_rb(mm, tmp, rb_link, rb_parent);
428 rb_link = &tmp->vm_rb.rb_right;
429 rb_parent = &tmp->vm_rb;
432 retval = copy_page_range(mm, oldmm, mpnt);
434 if (tmp->vm_ops && tmp->vm_ops->open)
435 tmp->vm_ops->open(tmp);
440 /* a new mm has just been created */
441 arch_dup_mmap(oldmm, mm);
444 up_write(&mm->mmap_sem);
446 up_write(&oldmm->mmap_sem);
448 fail_nomem_anon_vma_fork:
451 kmem_cache_free(vm_area_cachep, tmp);
454 vm_unacct_memory(charge);
458 static inline int mm_alloc_pgd(struct mm_struct * mm)
460 mm->pgd = pgd_alloc(mm);
461 if (unlikely(!mm->pgd))
466 static inline void mm_free_pgd(struct mm_struct * mm)
468 pgd_free(mm, mm->pgd);
471 #define dup_mmap(mm, oldmm) (0)
472 #define mm_alloc_pgd(mm) (0)
473 #define mm_free_pgd(mm)
474 #endif /* CONFIG_MMU */
476 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
478 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
479 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
481 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
483 static int __init coredump_filter_setup(char *s)
485 default_dump_filter =
486 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
487 MMF_DUMP_FILTER_MASK;
491 __setup("coredump_filter=", coredump_filter_setup);
493 #include <linux/init_task.h>
495 static void mm_init_aio(struct mm_struct *mm)
498 spin_lock_init(&mm->ioctx_lock);
499 INIT_HLIST_HEAD(&mm->ioctx_list);
503 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
505 atomic_set(&mm->mm_users, 1);
506 atomic_set(&mm->mm_count, 1);
507 init_rwsem(&mm->mmap_sem);
508 INIT_LIST_HEAD(&mm->mmlist);
509 mm->flags = (current->mm) ?
510 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
511 mm->core_state = NULL;
513 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
514 spin_lock_init(&mm->page_table_lock);
515 mm->free_area_cache = TASK_UNMAPPED_BASE;
516 mm->cached_hole_size = ~0UL;
518 mm_init_owner(mm, p);
519 atomic_set(&mm->oom_disable_count, 0);
521 if (likely(!mm_alloc_pgd(mm))) {
523 mmu_notifier_mm_init(mm);
532 * Allocate and initialize an mm_struct.
534 struct mm_struct * mm_alloc(void)
536 struct mm_struct * mm;
542 memset(mm, 0, sizeof(*mm));
544 return mm_init(mm, current);
548 * Called when the last reference to the mm
549 * is dropped: either by a lazy thread or by
550 * mmput. Free the page directory and the mm.
552 void __mmdrop(struct mm_struct *mm)
554 BUG_ON(mm == &init_mm);
557 mmu_notifier_mm_destroy(mm);
558 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
559 VM_BUG_ON(mm->pmd_huge_pte);
563 EXPORT_SYMBOL_GPL(__mmdrop);
566 * Decrement the use count and release all resources for an mm.
568 void mmput(struct mm_struct *mm)
572 if (atomic_dec_and_test(&mm->mm_users)) {
575 khugepaged_exit(mm); /* must run before exit_mmap */
577 set_mm_exe_file(mm, NULL);
578 if (!list_empty(&mm->mmlist)) {
579 spin_lock(&mmlist_lock);
580 list_del(&mm->mmlist);
581 spin_unlock(&mmlist_lock);
585 module_put(mm->binfmt->module);
589 EXPORT_SYMBOL_GPL(mmput);
592 * We added or removed a vma mapping the executable. The vmas are only mapped
593 * during exec and are not mapped with the mmap system call.
594 * Callers must hold down_write() on the mm's mmap_sem for these
596 void added_exe_file_vma(struct mm_struct *mm)
598 mm->num_exe_file_vmas++;
601 void removed_exe_file_vma(struct mm_struct *mm)
603 mm->num_exe_file_vmas--;
604 if ((mm->num_exe_file_vmas == 0) && mm->exe_file){
611 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
614 get_file(new_exe_file);
617 mm->exe_file = new_exe_file;
618 mm->num_exe_file_vmas = 0;
621 struct file *get_mm_exe_file(struct mm_struct *mm)
623 struct file *exe_file;
625 /* We need mmap_sem to protect against races with removal of
626 * VM_EXECUTABLE vmas */
627 down_read(&mm->mmap_sem);
628 exe_file = mm->exe_file;
631 up_read(&mm->mmap_sem);
635 static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
637 /* It's safe to write the exe_file pointer without exe_file_lock because
638 * this is called during fork when the task is not yet in /proc */
639 newmm->exe_file = get_mm_exe_file(oldmm);
643 * get_task_mm - acquire a reference to the task's mm
645 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
646 * this kernel workthread has transiently adopted a user mm with use_mm,
647 * to do its AIO) is not set and if so returns a reference to it, after
648 * bumping up the use count. User must release the mm via mmput()
649 * after use. Typically used by /proc and ptrace.
651 struct mm_struct *get_task_mm(struct task_struct *task)
653 struct mm_struct *mm;
658 if (task->flags & PF_KTHREAD)
661 atomic_inc(&mm->mm_users);
666 EXPORT_SYMBOL_GPL(get_task_mm);
668 /* Please note the differences between mmput and mm_release.
669 * mmput is called whenever we stop holding onto a mm_struct,
670 * error success whatever.
672 * mm_release is called after a mm_struct has been removed
673 * from the current process.
675 * This difference is important for error handling, when we
676 * only half set up a mm_struct for a new process and need to restore
677 * the old one. Because we mmput the new mm_struct before
678 * restoring the old one. . .
679 * Eric Biederman 10 January 1998
681 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
683 struct completion *vfork_done = tsk->vfork_done;
685 /* Get rid of any futexes when releasing the mm */
687 if (unlikely(tsk->robust_list)) {
688 exit_robust_list(tsk);
689 tsk->robust_list = NULL;
692 if (unlikely(tsk->compat_robust_list)) {
693 compat_exit_robust_list(tsk);
694 tsk->compat_robust_list = NULL;
697 if (unlikely(!list_empty(&tsk->pi_state_list)))
698 exit_pi_state_list(tsk);
701 /* Get rid of any cached register state */
702 deactivate_mm(tsk, mm);
704 /* notify parent sleeping on vfork() */
706 tsk->vfork_done = NULL;
707 complete(vfork_done);
711 * If we're exiting normally, clear a user-space tid field if
712 * requested. We leave this alone when dying by signal, to leave
713 * the value intact in a core dump, and to save the unnecessary
714 * trouble otherwise. Userland only wants this done for a sys_exit.
716 if (tsk->clear_child_tid) {
717 if (!(tsk->flags & PF_SIGNALED) &&
718 atomic_read(&mm->mm_users) > 1) {
720 * We don't check the error code - if userspace has
721 * not set up a proper pointer then tough luck.
723 put_user(0, tsk->clear_child_tid);
724 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
727 tsk->clear_child_tid = NULL;
732 * Allocate a new mm structure and copy contents from the
733 * mm structure of the passed in task structure.
735 struct mm_struct *dup_mm(struct task_struct *tsk)
737 struct mm_struct *mm, *oldmm = current->mm;
747 memcpy(mm, oldmm, sizeof(*mm));
750 /* Initializing for Swap token stuff */
751 mm->token_priority = 0;
752 mm->last_interval = 0;
754 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
755 mm->pmd_huge_pte = NULL;
758 if (!mm_init(mm, tsk))
761 if (init_new_context(tsk, mm))
764 dup_mm_exe_file(oldmm, mm);
766 err = dup_mmap(mm, oldmm);
770 mm->hiwater_rss = get_mm_rss(mm);
771 mm->hiwater_vm = mm->total_vm;
773 if (mm->binfmt && !try_module_get(mm->binfmt->module))
779 /* don't put binfmt in mmput, we haven't got module yet */
788 * If init_new_context() failed, we cannot use mmput() to free the mm
789 * because it calls destroy_context()
796 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
798 struct mm_struct * mm, *oldmm;
801 tsk->min_flt = tsk->maj_flt = 0;
802 tsk->nvcsw = tsk->nivcsw = 0;
803 #ifdef CONFIG_DETECT_HUNG_TASK
804 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
808 tsk->active_mm = NULL;
811 * Are we cloning a kernel thread?
813 * We need to steal a active VM for that..
819 if (clone_flags & CLONE_VM) {
820 atomic_inc(&oldmm->mm_users);
831 /* Initializing for Swap token stuff */
832 mm->token_priority = 0;
833 mm->last_interval = 0;
834 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
835 atomic_inc(&mm->oom_disable_count);
845 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
847 struct fs_struct *fs = current->fs;
848 if (clone_flags & CLONE_FS) {
849 /* tsk->fs is already what we want */
850 spin_lock(&fs->lock);
852 spin_unlock(&fs->lock);
856 spin_unlock(&fs->lock);
859 tsk->fs = copy_fs_struct(fs);
865 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
867 struct files_struct *oldf, *newf;
871 * A background process may not have any files ...
873 oldf = current->files;
877 if (clone_flags & CLONE_FILES) {
878 atomic_inc(&oldf->count);
882 newf = dup_fd(oldf, &error);
892 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
895 struct io_context *ioc = current->io_context;
900 * Share io context with parent, if CLONE_IO is set
902 if (clone_flags & CLONE_IO) {
903 tsk->io_context = ioc_task_link(ioc);
904 if (unlikely(!tsk->io_context))
906 } else if (ioprio_valid(ioc->ioprio)) {
907 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
908 if (unlikely(!tsk->io_context))
911 tsk->io_context->ioprio = ioc->ioprio;
917 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
919 struct sighand_struct *sig;
921 if (clone_flags & CLONE_SIGHAND) {
922 atomic_inc(¤t->sighand->count);
925 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
926 rcu_assign_pointer(tsk->sighand, sig);
929 atomic_set(&sig->count, 1);
930 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
934 void __cleanup_sighand(struct sighand_struct *sighand)
936 if (atomic_dec_and_test(&sighand->count))
937 kmem_cache_free(sighand_cachep, sighand);
942 * Initialize POSIX timer handling for a thread group.
944 static void posix_cpu_timers_init_group(struct signal_struct *sig)
946 unsigned long cpu_limit;
948 /* Thread group counters. */
949 thread_group_cputime_init(sig);
951 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
952 if (cpu_limit != RLIM_INFINITY) {
953 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
954 sig->cputimer.running = 1;
957 /* The timer lists. */
958 INIT_LIST_HEAD(&sig->cpu_timers[0]);
959 INIT_LIST_HEAD(&sig->cpu_timers[1]);
960 INIT_LIST_HEAD(&sig->cpu_timers[2]);
963 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
965 struct signal_struct *sig;
967 if (clone_flags & CLONE_THREAD)
970 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
976 atomic_set(&sig->live, 1);
977 atomic_set(&sig->sigcnt, 1);
978 init_waitqueue_head(&sig->wait_chldexit);
979 if (clone_flags & CLONE_NEWPID)
980 sig->flags |= SIGNAL_UNKILLABLE;
981 sig->curr_target = tsk;
982 init_sigpending(&sig->shared_pending);
983 INIT_LIST_HEAD(&sig->posix_timers);
985 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
986 sig->real_timer.function = it_real_fn;
988 task_lock(current->group_leader);
989 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
990 task_unlock(current->group_leader);
992 posix_cpu_timers_init_group(sig);
995 sched_autogroup_fork(sig);
997 #ifdef CONFIG_CGROUPS
998 init_rwsem(&sig->threadgroup_fork_lock);
1001 sig->oom_adj = current->signal->oom_adj;
1002 sig->oom_score_adj = current->signal->oom_score_adj;
1003 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1005 mutex_init(&sig->cred_guard_mutex);
1010 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
1012 unsigned long new_flags = p->flags;
1014 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
1015 new_flags |= PF_FORKNOEXEC;
1016 new_flags |= PF_STARTING;
1017 p->flags = new_flags;
1018 clear_freeze_flag(p);
1021 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1023 current->clear_child_tid = tidptr;
1025 return task_pid_vnr(current);
1028 static void rt_mutex_init_task(struct task_struct *p)
1030 raw_spin_lock_init(&p->pi_lock);
1031 #ifdef CONFIG_RT_MUTEXES
1032 plist_head_init(&p->pi_waiters);
1033 p->pi_blocked_on = NULL;
1037 #ifdef CONFIG_MM_OWNER
1038 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1042 #endif /* CONFIG_MM_OWNER */
1045 * Initialize POSIX timer handling for a single task.
1047 static void posix_cpu_timers_init(struct task_struct *tsk)
1049 tsk->cputime_expires.prof_exp = cputime_zero;
1050 tsk->cputime_expires.virt_exp = cputime_zero;
1051 tsk->cputime_expires.sched_exp = 0;
1052 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1053 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1054 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1058 * This creates a new process as a copy of the old one,
1059 * but does not actually start it yet.
1061 * It copies the registers, and all the appropriate
1062 * parts of the process environment (as per the clone
1063 * flags). The actual kick-off is left to the caller.
1065 static struct task_struct *copy_process(unsigned long clone_flags,
1066 unsigned long stack_start,
1067 struct pt_regs *regs,
1068 unsigned long stack_size,
1069 int __user *child_tidptr,
1074 struct task_struct *p;
1075 int cgroup_callbacks_done = 0;
1077 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1078 return ERR_PTR(-EINVAL);
1081 * Thread groups must share signals as well, and detached threads
1082 * can only be started up within the thread group.
1084 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1085 return ERR_PTR(-EINVAL);
1088 * Shared signal handlers imply shared VM. By way of the above,
1089 * thread groups also imply shared VM. Blocking this case allows
1090 * for various simplifications in other code.
1092 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1093 return ERR_PTR(-EINVAL);
1096 * Siblings of global init remain as zombies on exit since they are
1097 * not reaped by their parent (swapper). To solve this and to avoid
1098 * multi-rooted process trees, prevent global and container-inits
1099 * from creating siblings.
1101 if ((clone_flags & CLONE_PARENT) &&
1102 current->signal->flags & SIGNAL_UNKILLABLE)
1103 return ERR_PTR(-EINVAL);
1105 retval = security_task_create(clone_flags);
1110 p = dup_task_struct(current);
1114 ftrace_graph_init_task(p);
1116 rt_mutex_init_task(p);
1118 #ifdef CONFIG_PROVE_LOCKING
1119 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1120 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1123 if (atomic_read(&p->real_cred->user->processes) >=
1124 task_rlimit(p, RLIMIT_NPROC)) {
1125 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1126 p->real_cred->user != INIT_USER)
1130 retval = copy_creds(p, clone_flags);
1135 * If multiple threads are within copy_process(), then this check
1136 * triggers too late. This doesn't hurt, the check is only there
1137 * to stop root fork bombs.
1140 if (nr_threads >= max_threads)
1141 goto bad_fork_cleanup_count;
1143 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1144 goto bad_fork_cleanup_count;
1147 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1148 copy_flags(clone_flags, p);
1149 INIT_LIST_HEAD(&p->children);
1150 INIT_LIST_HEAD(&p->sibling);
1151 rcu_copy_process(p);
1152 p->vfork_done = NULL;
1153 spin_lock_init(&p->alloc_lock);
1155 init_sigpending(&p->pending);
1157 p->utime = cputime_zero;
1158 p->stime = cputime_zero;
1159 p->gtime = cputime_zero;
1160 p->utimescaled = cputime_zero;
1161 p->stimescaled = cputime_zero;
1162 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1163 p->prev_utime = cputime_zero;
1164 p->prev_stime = cputime_zero;
1166 #if defined(SPLIT_RSS_COUNTING)
1167 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1170 p->default_timer_slack_ns = current->timer_slack_ns;
1172 task_io_accounting_init(&p->ioac);
1173 acct_clear_integrals(p);
1175 posix_cpu_timers_init(p);
1177 do_posix_clock_monotonic_gettime(&p->start_time);
1178 p->real_start_time = p->start_time;
1179 monotonic_to_bootbased(&p->real_start_time);
1180 p->io_context = NULL;
1181 p->audit_context = NULL;
1182 if (clone_flags & CLONE_THREAD)
1183 threadgroup_fork_read_lock(current);
1186 p->mempolicy = mpol_dup(p->mempolicy);
1187 if (IS_ERR(p->mempolicy)) {
1188 retval = PTR_ERR(p->mempolicy);
1189 p->mempolicy = NULL;
1190 goto bad_fork_cleanup_cgroup;
1192 mpol_fix_fork_child_flag(p);
1194 #ifdef CONFIG_TRACE_IRQFLAGS
1196 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1197 p->hardirqs_enabled = 1;
1199 p->hardirqs_enabled = 0;
1201 p->hardirq_enable_ip = 0;
1202 p->hardirq_enable_event = 0;
1203 p->hardirq_disable_ip = _THIS_IP_;
1204 p->hardirq_disable_event = 0;
1205 p->softirqs_enabled = 1;
1206 p->softirq_enable_ip = _THIS_IP_;
1207 p->softirq_enable_event = 0;
1208 p->softirq_disable_ip = 0;
1209 p->softirq_disable_event = 0;
1210 p->hardirq_context = 0;
1211 p->softirq_context = 0;
1213 #ifdef CONFIG_LOCKDEP
1214 p->lockdep_depth = 0; /* no locks held yet */
1215 p->curr_chain_key = 0;
1216 p->lockdep_recursion = 0;
1219 #ifdef CONFIG_DEBUG_MUTEXES
1220 p->blocked_on = NULL; /* not blocked yet */
1222 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1223 p->memcg_batch.do_batch = 0;
1224 p->memcg_batch.memcg = NULL;
1227 /* Perform scheduler related setup. Assign this task to a CPU. */
1230 retval = perf_event_init_task(p);
1232 goto bad_fork_cleanup_policy;
1234 if ((retval = audit_alloc(p)))
1235 goto bad_fork_cleanup_policy;
1236 /* copy all the process information */
1237 if ((retval = copy_semundo(clone_flags, p)))
1238 goto bad_fork_cleanup_audit;
1239 if ((retval = copy_files(clone_flags, p)))
1240 goto bad_fork_cleanup_semundo;
1241 if ((retval = copy_fs(clone_flags, p)))
1242 goto bad_fork_cleanup_files;
1243 if ((retval = copy_sighand(clone_flags, p)))
1244 goto bad_fork_cleanup_fs;
1245 if ((retval = copy_signal(clone_flags, p)))
1246 goto bad_fork_cleanup_sighand;
1247 if ((retval = copy_mm(clone_flags, p)))
1248 goto bad_fork_cleanup_signal;
1249 if ((retval = copy_namespaces(clone_flags, p)))
1250 goto bad_fork_cleanup_mm;
1251 if ((retval = copy_io(clone_flags, p)))
1252 goto bad_fork_cleanup_namespaces;
1253 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1255 goto bad_fork_cleanup_io;
1257 if (pid != &init_struct_pid) {
1259 pid = alloc_pid(p->nsproxy->pid_ns);
1261 goto bad_fork_cleanup_io;
1264 p->pid = pid_nr(pid);
1266 if (clone_flags & CLONE_THREAD)
1267 p->tgid = current->tgid;
1269 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1271 * Clear TID on mm_release()?
1273 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1278 p->robust_list = NULL;
1279 #ifdef CONFIG_COMPAT
1280 p->compat_robust_list = NULL;
1282 INIT_LIST_HEAD(&p->pi_state_list);
1283 p->pi_state_cache = NULL;
1286 * sigaltstack should be cleared when sharing the same VM
1288 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1289 p->sas_ss_sp = p->sas_ss_size = 0;
1292 * Syscall tracing and stepping should be turned off in the
1293 * child regardless of CLONE_PTRACE.
1295 user_disable_single_step(p);
1296 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1297 #ifdef TIF_SYSCALL_EMU
1298 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1300 clear_all_latency_tracing(p);
1302 /* ok, now we should be set up.. */
1303 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1304 p->pdeath_signal = 0;
1308 * Ok, make it visible to the rest of the system.
1309 * We dont wake it up yet.
1311 p->group_leader = p;
1312 INIT_LIST_HEAD(&p->thread_group);
1314 /* Now that the task is set up, run cgroup callbacks if
1315 * necessary. We need to run them before the task is visible
1316 * on the tasklist. */
1317 cgroup_fork_callbacks(p);
1318 cgroup_callbacks_done = 1;
1320 /* Need tasklist lock for parent etc handling! */
1321 write_lock_irq(&tasklist_lock);
1323 /* CLONE_PARENT re-uses the old parent */
1324 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1325 p->real_parent = current->real_parent;
1326 p->parent_exec_id = current->parent_exec_id;
1328 p->real_parent = current;
1329 p->parent_exec_id = current->self_exec_id;
1332 spin_lock(¤t->sighand->siglock);
1335 * Process group and session signals need to be delivered to just the
1336 * parent before the fork or both the parent and the child after the
1337 * fork. Restart if a signal comes in before we add the new process to
1338 * it's process group.
1339 * A fatal signal pending means that current will exit, so the new
1340 * thread can't slip out of an OOM kill (or normal SIGKILL).
1342 recalc_sigpending();
1343 if (signal_pending(current)) {
1344 spin_unlock(¤t->sighand->siglock);
1345 write_unlock_irq(&tasklist_lock);
1346 retval = -ERESTARTNOINTR;
1347 goto bad_fork_free_pid;
1350 if (clone_flags & CLONE_THREAD) {
1351 current->signal->nr_threads++;
1352 atomic_inc(¤t->signal->live);
1353 atomic_inc(¤t->signal->sigcnt);
1354 p->group_leader = current->group_leader;
1355 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1358 if (likely(p->pid)) {
1359 tracehook_finish_clone(p, clone_flags, trace);
1361 if (thread_group_leader(p)) {
1362 if (is_child_reaper(pid))
1363 p->nsproxy->pid_ns->child_reaper = p;
1365 p->signal->leader_pid = pid;
1366 p->signal->tty = tty_kref_get(current->signal->tty);
1367 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1368 attach_pid(p, PIDTYPE_SID, task_session(current));
1369 list_add_tail(&p->sibling, &p->real_parent->children);
1370 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1371 __this_cpu_inc(process_counts);
1373 attach_pid(p, PIDTYPE_PID, pid);
1378 spin_unlock(¤t->sighand->siglock);
1379 write_unlock_irq(&tasklist_lock);
1380 proc_fork_connector(p);
1381 cgroup_post_fork(p);
1382 if (clone_flags & CLONE_THREAD)
1383 threadgroup_fork_read_unlock(current);
1388 if (pid != &init_struct_pid)
1390 bad_fork_cleanup_io:
1393 bad_fork_cleanup_namespaces:
1394 exit_task_namespaces(p);
1395 bad_fork_cleanup_mm:
1398 if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
1399 atomic_dec(&p->mm->oom_disable_count);
1403 bad_fork_cleanup_signal:
1404 if (!(clone_flags & CLONE_THREAD))
1405 free_signal_struct(p->signal);
1406 bad_fork_cleanup_sighand:
1407 __cleanup_sighand(p->sighand);
1408 bad_fork_cleanup_fs:
1409 exit_fs(p); /* blocking */
1410 bad_fork_cleanup_files:
1411 exit_files(p); /* blocking */
1412 bad_fork_cleanup_semundo:
1414 bad_fork_cleanup_audit:
1416 bad_fork_cleanup_policy:
1417 perf_event_free_task(p);
1419 mpol_put(p->mempolicy);
1420 bad_fork_cleanup_cgroup:
1422 if (clone_flags & CLONE_THREAD)
1423 threadgroup_fork_read_unlock(current);
1424 cgroup_exit(p, cgroup_callbacks_done);
1425 delayacct_tsk_free(p);
1426 module_put(task_thread_info(p)->exec_domain->module);
1427 bad_fork_cleanup_count:
1428 atomic_dec(&p->cred->user->processes);
1433 return ERR_PTR(retval);
1436 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1438 memset(regs, 0, sizeof(struct pt_regs));
1442 static inline void init_idle_pids(struct pid_link *links)
1446 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1447 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1448 links[type].pid = &init_struct_pid;
1452 struct task_struct * __cpuinit fork_idle(int cpu)
1454 struct task_struct *task;
1455 struct pt_regs regs;
1457 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1458 &init_struct_pid, 0);
1459 if (!IS_ERR(task)) {
1460 init_idle_pids(task->pids);
1461 init_idle(task, cpu);
1468 * Ok, this is the main fork-routine.
1470 * It copies the process, and if successful kick-starts
1471 * it and waits for it to finish using the VM if required.
1473 long do_fork(unsigned long clone_flags,
1474 unsigned long stack_start,
1475 struct pt_regs *regs,
1476 unsigned long stack_size,
1477 int __user *parent_tidptr,
1478 int __user *child_tidptr)
1480 struct task_struct *p;
1485 * Do some preliminary argument and permissions checking before we
1486 * actually start allocating stuff
1488 if (clone_flags & CLONE_NEWUSER) {
1489 if (clone_flags & CLONE_THREAD)
1491 /* hopefully this check will go away when userns support is
1494 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1495 !capable(CAP_SETGID))
1500 * When called from kernel_thread, don't do user tracing stuff.
1502 if (likely(user_mode(regs)))
1503 trace = tracehook_prepare_clone(clone_flags);
1505 p = copy_process(clone_flags, stack_start, regs, stack_size,
1506 child_tidptr, NULL, trace);
1508 * Do this prior waking up the new thread - the thread pointer
1509 * might get invalid after that point, if the thread exits quickly.
1512 struct completion vfork;
1514 trace_sched_process_fork(current, p);
1516 nr = task_pid_vnr(p);
1518 if (clone_flags & CLONE_PARENT_SETTID)
1519 put_user(nr, parent_tidptr);
1521 if (clone_flags & CLONE_VFORK) {
1522 p->vfork_done = &vfork;
1523 init_completion(&vfork);
1526 audit_finish_fork(p);
1527 tracehook_report_clone(regs, clone_flags, nr, p);
1530 * We set PF_STARTING at creation in case tracing wants to
1531 * use this to distinguish a fully live task from one that
1532 * hasn't gotten to tracehook_report_clone() yet. Now we
1533 * clear it and set the child going.
1535 p->flags &= ~PF_STARTING;
1537 wake_up_new_task(p);
1539 tracehook_report_clone_complete(trace, regs,
1540 clone_flags, nr, p);
1542 if (clone_flags & CLONE_VFORK) {
1543 freezer_do_not_count();
1544 wait_for_completion(&vfork);
1546 tracehook_report_vfork_done(p, nr);
1554 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1555 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1558 static void sighand_ctor(void *data)
1560 struct sighand_struct *sighand = data;
1562 spin_lock_init(&sighand->siglock);
1563 init_waitqueue_head(&sighand->signalfd_wqh);
1566 void __init proc_caches_init(void)
1568 sighand_cachep = kmem_cache_create("sighand_cache",
1569 sizeof(struct sighand_struct), 0,
1570 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1571 SLAB_NOTRACK, sighand_ctor);
1572 signal_cachep = kmem_cache_create("signal_cache",
1573 sizeof(struct signal_struct), 0,
1574 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1575 files_cachep = kmem_cache_create("files_cache",
1576 sizeof(struct files_struct), 0,
1577 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1578 fs_cachep = kmem_cache_create("fs_cache",
1579 sizeof(struct fs_struct), 0,
1580 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1582 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1583 * whole struct cpumask for the OFFSTACK case. We could change
1584 * this to *only* allocate as much of it as required by the
1585 * maximum number of CPU's we can ever have. The cpumask_allocation
1586 * is at the end of the structure, exactly for that reason.
1588 mm_cachep = kmem_cache_create("mm_struct",
1589 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1590 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1591 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1596 * Check constraints on flags passed to the unshare system call.
1598 static int check_unshare_flags(unsigned long unshare_flags)
1600 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1601 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1602 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1605 * Not implemented, but pretend it works if there is nothing to
1606 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1607 * needs to unshare vm.
1609 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1610 /* FIXME: get_task_mm() increments ->mm_users */
1611 if (atomic_read(¤t->mm->mm_users) > 1)
1619 * Unshare the filesystem structure if it is being shared
1621 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1623 struct fs_struct *fs = current->fs;
1625 if (!(unshare_flags & CLONE_FS) || !fs)
1628 /* don't need lock here; in the worst case we'll do useless copy */
1632 *new_fsp = copy_fs_struct(fs);
1640 * Unshare file descriptor table if it is being shared
1642 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1644 struct files_struct *fd = current->files;
1647 if ((unshare_flags & CLONE_FILES) &&
1648 (fd && atomic_read(&fd->count) > 1)) {
1649 *new_fdp = dup_fd(fd, &error);
1658 * unshare allows a process to 'unshare' part of the process
1659 * context which was originally shared using clone. copy_*
1660 * functions used by do_fork() cannot be used here directly
1661 * because they modify an inactive task_struct that is being
1662 * constructed. Here we are modifying the current, active,
1665 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1667 struct fs_struct *fs, *new_fs = NULL;
1668 struct files_struct *fd, *new_fd = NULL;
1669 struct nsproxy *new_nsproxy = NULL;
1673 err = check_unshare_flags(unshare_flags);
1675 goto bad_unshare_out;
1678 * If unsharing namespace, must also unshare filesystem information.
1680 if (unshare_flags & CLONE_NEWNS)
1681 unshare_flags |= CLONE_FS;
1683 * CLONE_NEWIPC must also detach from the undolist: after switching
1684 * to a new ipc namespace, the semaphore arrays from the old
1685 * namespace are unreachable.
1687 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1689 if ((err = unshare_fs(unshare_flags, &new_fs)))
1690 goto bad_unshare_out;
1691 if ((err = unshare_fd(unshare_flags, &new_fd)))
1692 goto bad_unshare_cleanup_fs;
1693 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
1695 goto bad_unshare_cleanup_fd;
1697 if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
1700 * CLONE_SYSVSEM is equivalent to sys_exit().
1706 switch_task_namespaces(current, new_nsproxy);
1714 spin_lock(&fs->lock);
1715 current->fs = new_fs;
1720 spin_unlock(&fs->lock);
1724 fd = current->files;
1725 current->files = new_fd;
1729 task_unlock(current);
1733 put_nsproxy(new_nsproxy);
1735 bad_unshare_cleanup_fd:
1737 put_files_struct(new_fd);
1739 bad_unshare_cleanup_fs:
1741 free_fs_struct(new_fs);
1748 * Helper to unshare the files of the current task.
1749 * We don't want to expose copy_files internals to
1750 * the exec layer of the kernel.
1753 int unshare_files(struct files_struct **displaced)
1755 struct task_struct *task = current;
1756 struct files_struct *copy = NULL;
1759 error = unshare_fd(CLONE_FILES, ©);
1760 if (error || !copy) {
1764 *displaced = task->files;