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>
80 #define CREATE_TRACE_POINTS
81 #include <trace/events/task.h>
84 * Protected counters by write_lock_irq(&tasklist_lock)
86 unsigned long total_forks; /* Handle normal Linux uptimes. */
87 int nr_threads; /* The idle threads do not count.. */
89 int max_threads; /* tunable limit on nr_threads */
91 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
93 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
95 #ifdef CONFIG_PROVE_RCU
96 int lockdep_tasklist_lock_is_held(void)
98 return lockdep_is_held(&tasklist_lock);
100 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
101 #endif /* #ifdef CONFIG_PROVE_RCU */
103 int nr_processes(void)
108 for_each_possible_cpu(cpu)
109 total += per_cpu(process_counts, cpu);
114 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
115 # define alloc_task_struct_node(node) \
116 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
117 # define free_task_struct(tsk) \
118 kmem_cache_free(task_struct_cachep, (tsk))
119 static struct kmem_cache *task_struct_cachep;
122 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
123 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
126 #ifdef CONFIG_DEBUG_STACK_USAGE
127 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
129 gfp_t mask = GFP_KERNEL;
131 struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER);
133 return page ? page_address(page) : NULL;
136 static inline void free_thread_info(struct thread_info *ti)
138 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
142 /* SLAB cache for signal_struct structures (tsk->signal) */
143 static struct kmem_cache *signal_cachep;
145 /* SLAB cache for sighand_struct structures (tsk->sighand) */
146 struct kmem_cache *sighand_cachep;
148 /* SLAB cache for files_struct structures (tsk->files) */
149 struct kmem_cache *files_cachep;
151 /* SLAB cache for fs_struct structures (tsk->fs) */
152 struct kmem_cache *fs_cachep;
154 /* SLAB cache for vm_area_struct structures */
155 struct kmem_cache *vm_area_cachep;
157 /* SLAB cache for mm_struct structures (tsk->mm) */
158 static struct kmem_cache *mm_cachep;
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 account_kernel_stack(tsk->stack, -1);
170 free_thread_info(tsk->stack);
171 rt_mutex_debug_task_free(tsk);
172 ftrace_graph_exit_task(tsk);
173 free_task_struct(tsk);
175 EXPORT_SYMBOL(free_task);
177 static inline void free_signal_struct(struct signal_struct *sig)
179 taskstats_tgid_free(sig);
180 sched_autogroup_exit(sig);
181 kmem_cache_free(signal_cachep, sig);
184 static inline void put_signal_struct(struct signal_struct *sig)
186 if (atomic_dec_and_test(&sig->sigcnt))
187 free_signal_struct(sig);
190 void __put_task_struct(struct task_struct *tsk)
192 WARN_ON(!tsk->exit_state);
193 WARN_ON(atomic_read(&tsk->usage));
194 WARN_ON(tsk == current);
197 delayacct_tsk_free(tsk);
198 put_signal_struct(tsk->signal);
200 if (!profile_handoff_task(tsk))
203 EXPORT_SYMBOL_GPL(__put_task_struct);
206 * macro override instead of weak attribute alias, to workaround
207 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
209 #ifndef arch_task_cache_init
210 #define arch_task_cache_init()
213 void __init fork_init(unsigned long mempages)
215 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
216 #ifndef ARCH_MIN_TASKALIGN
217 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
219 /* create a slab on which task_structs can be allocated */
221 kmem_cache_create("task_struct", sizeof(struct task_struct),
222 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
225 /* do the arch specific task caches init */
226 arch_task_cache_init();
229 * The default maximum number of threads is set to a safe
230 * value: the thread structures can take up at most half
233 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
236 * we need to allow at least 20 threads to boot a system
238 if (max_threads < 20)
241 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
242 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
243 init_task.signal->rlim[RLIMIT_SIGPENDING] =
244 init_task.signal->rlim[RLIMIT_NPROC];
247 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
248 struct task_struct *src)
254 static struct task_struct *dup_task_struct(struct task_struct *orig)
256 struct task_struct *tsk;
257 struct thread_info *ti;
258 unsigned long *stackend;
259 int node = tsk_fork_get_node(orig);
262 prepare_to_copy(orig);
264 tsk = alloc_task_struct_node(node);
268 ti = alloc_thread_info_node(tsk, node);
270 free_task_struct(tsk);
274 err = arch_dup_task_struct(tsk, orig);
280 setup_thread_stack(tsk, orig);
281 clear_user_return_notifier(tsk);
282 clear_tsk_need_resched(tsk);
283 stackend = end_of_stack(tsk);
284 *stackend = STACK_END_MAGIC; /* for overflow detection */
286 #ifdef CONFIG_CC_STACKPROTECTOR
287 tsk->stack_canary = get_random_int();
291 * One for us, one for whoever does the "release_task()" (usually
294 atomic_set(&tsk->usage, 2);
295 #ifdef CONFIG_BLK_DEV_IO_TRACE
298 tsk->splice_pipe = NULL;
300 account_kernel_stack(ti, 1);
305 free_thread_info(ti);
306 free_task_struct(tsk);
311 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
313 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
314 struct rb_node **rb_link, *rb_parent;
316 unsigned long charge;
317 struct mempolicy *pol;
319 down_write(&oldmm->mmap_sem);
320 flush_cache_dup_mm(oldmm);
322 * Not linked in yet - no deadlock potential:
324 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
328 mm->mmap_cache = NULL;
329 mm->free_area_cache = oldmm->mmap_base;
330 mm->cached_hole_size = ~0UL;
332 cpumask_clear(mm_cpumask(mm));
334 rb_link = &mm->mm_rb.rb_node;
337 retval = ksm_fork(mm, oldmm);
340 retval = khugepaged_fork(mm, oldmm);
345 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
348 if (mpnt->vm_flags & VM_DONTCOPY) {
349 long pages = vma_pages(mpnt);
350 mm->total_vm -= pages;
351 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
356 if (mpnt->vm_flags & VM_ACCOUNT) {
357 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
358 if (security_vm_enough_memory(len))
362 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
366 INIT_LIST_HEAD(&tmp->anon_vma_chain);
367 pol = mpol_dup(vma_policy(mpnt));
368 retval = PTR_ERR(pol);
370 goto fail_nomem_policy;
371 vma_set_policy(tmp, pol);
373 if (anon_vma_fork(tmp, mpnt))
374 goto fail_nomem_anon_vma_fork;
375 tmp->vm_flags &= ~VM_LOCKED;
376 tmp->vm_next = tmp->vm_prev = NULL;
379 struct inode *inode = file->f_path.dentry->d_inode;
380 struct address_space *mapping = file->f_mapping;
383 if (tmp->vm_flags & VM_DENYWRITE)
384 atomic_dec(&inode->i_writecount);
385 mutex_lock(&mapping->i_mmap_mutex);
386 if (tmp->vm_flags & VM_SHARED)
387 mapping->i_mmap_writable++;
388 flush_dcache_mmap_lock(mapping);
389 /* insert tmp into the share list, just after mpnt */
390 vma_prio_tree_add(tmp, mpnt);
391 flush_dcache_mmap_unlock(mapping);
392 mutex_unlock(&mapping->i_mmap_mutex);
396 * Clear hugetlb-related page reserves for children. This only
397 * affects MAP_PRIVATE mappings. Faults generated by the child
398 * are not guaranteed to succeed, even if read-only
400 if (is_vm_hugetlb_page(tmp))
401 reset_vma_resv_huge_pages(tmp);
404 * Link in the new vma and copy the page table entries.
407 pprev = &tmp->vm_next;
411 __vma_link_rb(mm, tmp, rb_link, rb_parent);
412 rb_link = &tmp->vm_rb.rb_right;
413 rb_parent = &tmp->vm_rb;
416 retval = copy_page_range(mm, oldmm, mpnt);
418 if (tmp->vm_ops && tmp->vm_ops->open)
419 tmp->vm_ops->open(tmp);
424 /* a new mm has just been created */
425 arch_dup_mmap(oldmm, mm);
428 up_write(&mm->mmap_sem);
430 up_write(&oldmm->mmap_sem);
432 fail_nomem_anon_vma_fork:
435 kmem_cache_free(vm_area_cachep, tmp);
438 vm_unacct_memory(charge);
442 static inline int mm_alloc_pgd(struct mm_struct *mm)
444 mm->pgd = pgd_alloc(mm);
445 if (unlikely(!mm->pgd))
450 static inline void mm_free_pgd(struct mm_struct *mm)
452 pgd_free(mm, mm->pgd);
455 #define dup_mmap(mm, oldmm) (0)
456 #define mm_alloc_pgd(mm) (0)
457 #define mm_free_pgd(mm)
458 #endif /* CONFIG_MMU */
460 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
462 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
463 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
465 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
467 static int __init coredump_filter_setup(char *s)
469 default_dump_filter =
470 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
471 MMF_DUMP_FILTER_MASK;
475 __setup("coredump_filter=", coredump_filter_setup);
477 #include <linux/init_task.h>
479 static void mm_init_aio(struct mm_struct *mm)
482 spin_lock_init(&mm->ioctx_lock);
483 INIT_HLIST_HEAD(&mm->ioctx_list);
487 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
489 atomic_set(&mm->mm_users, 1);
490 atomic_set(&mm->mm_count, 1);
491 init_rwsem(&mm->mmap_sem);
492 INIT_LIST_HEAD(&mm->mmlist);
493 mm->flags = (current->mm) ?
494 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
495 mm->core_state = NULL;
497 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
498 spin_lock_init(&mm->page_table_lock);
499 mm->free_area_cache = TASK_UNMAPPED_BASE;
500 mm->cached_hole_size = ~0UL;
502 mm_init_owner(mm, p);
504 if (likely(!mm_alloc_pgd(mm))) {
506 mmu_notifier_mm_init(mm);
515 * Allocate and initialize an mm_struct.
517 struct mm_struct *mm_alloc(void)
519 struct mm_struct *mm;
525 memset(mm, 0, sizeof(*mm));
527 return mm_init(mm, current);
531 * Called when the last reference to the mm
532 * is dropped: either by a lazy thread or by
533 * mmput. Free the page directory and the mm.
535 void __mmdrop(struct mm_struct *mm)
537 BUG_ON(mm == &init_mm);
540 mmu_notifier_mm_destroy(mm);
541 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
542 VM_BUG_ON(mm->pmd_huge_pte);
546 EXPORT_SYMBOL_GPL(__mmdrop);
549 * Decrement the use count and release all resources for an mm.
551 void mmput(struct mm_struct *mm)
555 if (atomic_dec_and_test(&mm->mm_users)) {
558 khugepaged_exit(mm); /* must run before exit_mmap */
560 set_mm_exe_file(mm, NULL);
561 if (!list_empty(&mm->mmlist)) {
562 spin_lock(&mmlist_lock);
563 list_del(&mm->mmlist);
564 spin_unlock(&mmlist_lock);
568 module_put(mm->binfmt->module);
572 EXPORT_SYMBOL_GPL(mmput);
575 * We added or removed a vma mapping the executable. The vmas are only mapped
576 * during exec and are not mapped with the mmap system call.
577 * Callers must hold down_write() on the mm's mmap_sem for these
579 void added_exe_file_vma(struct mm_struct *mm)
581 mm->num_exe_file_vmas++;
584 void removed_exe_file_vma(struct mm_struct *mm)
586 mm->num_exe_file_vmas--;
587 if ((mm->num_exe_file_vmas == 0) && mm->exe_file) {
594 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
597 get_file(new_exe_file);
600 mm->exe_file = new_exe_file;
601 mm->num_exe_file_vmas = 0;
604 struct file *get_mm_exe_file(struct mm_struct *mm)
606 struct file *exe_file;
608 /* We need mmap_sem to protect against races with removal of
609 * VM_EXECUTABLE vmas */
610 down_read(&mm->mmap_sem);
611 exe_file = mm->exe_file;
614 up_read(&mm->mmap_sem);
618 static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
620 /* It's safe to write the exe_file pointer without exe_file_lock because
621 * this is called during fork when the task is not yet in /proc */
622 newmm->exe_file = get_mm_exe_file(oldmm);
626 * get_task_mm - acquire a reference to the task's mm
628 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
629 * this kernel workthread has transiently adopted a user mm with use_mm,
630 * to do its AIO) is not set and if so returns a reference to it, after
631 * bumping up the use count. User must release the mm via mmput()
632 * after use. Typically used by /proc and ptrace.
634 struct mm_struct *get_task_mm(struct task_struct *task)
636 struct mm_struct *mm;
641 if (task->flags & PF_KTHREAD)
644 atomic_inc(&mm->mm_users);
649 EXPORT_SYMBOL_GPL(get_task_mm);
651 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
653 struct mm_struct *mm;
656 err = mutex_lock_killable(&task->signal->cred_guard_mutex);
660 mm = get_task_mm(task);
661 if (mm && mm != current->mm &&
662 !ptrace_may_access(task, mode)) {
664 mm = ERR_PTR(-EACCES);
666 mutex_unlock(&task->signal->cred_guard_mutex);
671 void complete_vfork_done(struct task_struct *tsk)
673 struct completion *vfork;
676 vfork = tsk->vfork_done;
678 tsk->vfork_done = NULL;
684 static int wait_for_vfork_done(struct task_struct *child,
685 struct completion *vfork)
689 freezer_do_not_count();
690 killed = wait_for_completion_killable(vfork);
695 child->vfork_done = NULL;
699 put_task_struct(child);
703 /* Please note the differences between mmput and mm_release.
704 * mmput is called whenever we stop holding onto a mm_struct,
705 * error success whatever.
707 * mm_release is called after a mm_struct has been removed
708 * from the current process.
710 * This difference is important for error handling, when we
711 * only half set up a mm_struct for a new process and need to restore
712 * the old one. Because we mmput the new mm_struct before
713 * restoring the old one. . .
714 * Eric Biederman 10 January 1998
716 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
718 /* Get rid of any futexes when releasing the mm */
720 if (unlikely(tsk->robust_list)) {
721 exit_robust_list(tsk);
722 tsk->robust_list = NULL;
725 if (unlikely(tsk->compat_robust_list)) {
726 compat_exit_robust_list(tsk);
727 tsk->compat_robust_list = NULL;
730 if (unlikely(!list_empty(&tsk->pi_state_list)))
731 exit_pi_state_list(tsk);
734 /* Get rid of any cached register state */
735 deactivate_mm(tsk, mm);
738 complete_vfork_done(tsk);
741 * If we're exiting normally, clear a user-space tid field if
742 * requested. We leave this alone when dying by signal, to leave
743 * the value intact in a core dump, and to save the unnecessary
744 * trouble, say, a killed vfork parent shouldn't touch this mm.
745 * Userland only wants this done for a sys_exit.
747 if (tsk->clear_child_tid) {
748 if (!(tsk->flags & PF_SIGNALED) &&
749 atomic_read(&mm->mm_users) > 1) {
751 * We don't check the error code - if userspace has
752 * not set up a proper pointer then tough luck.
754 put_user(0, tsk->clear_child_tid);
755 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
758 tsk->clear_child_tid = NULL;
763 * Allocate a new mm structure and copy contents from the
764 * mm structure of the passed in task structure.
766 struct mm_struct *dup_mm(struct task_struct *tsk)
768 struct mm_struct *mm, *oldmm = current->mm;
778 memcpy(mm, oldmm, sizeof(*mm));
781 /* Initializing for Swap token stuff */
782 mm->token_priority = 0;
783 mm->last_interval = 0;
785 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
786 mm->pmd_huge_pte = NULL;
789 if (!mm_init(mm, tsk))
792 if (init_new_context(tsk, mm))
795 dup_mm_exe_file(oldmm, mm);
797 err = dup_mmap(mm, oldmm);
801 mm->hiwater_rss = get_mm_rss(mm);
802 mm->hiwater_vm = mm->total_vm;
804 if (mm->binfmt && !try_module_get(mm->binfmt->module))
810 /* don't put binfmt in mmput, we haven't got module yet */
819 * If init_new_context() failed, we cannot use mmput() to free the mm
820 * because it calls destroy_context()
827 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
829 struct mm_struct *mm, *oldmm;
832 tsk->min_flt = tsk->maj_flt = 0;
833 tsk->nvcsw = tsk->nivcsw = 0;
834 #ifdef CONFIG_DETECT_HUNG_TASK
835 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
839 tsk->active_mm = NULL;
842 * Are we cloning a kernel thread?
844 * We need to steal a active VM for that..
850 if (clone_flags & CLONE_VM) {
851 atomic_inc(&oldmm->mm_users);
862 /* Initializing for Swap token stuff */
863 mm->token_priority = 0;
864 mm->last_interval = 0;
874 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
876 struct fs_struct *fs = current->fs;
877 if (clone_flags & CLONE_FS) {
878 /* tsk->fs is already what we want */
879 spin_lock(&fs->lock);
881 spin_unlock(&fs->lock);
885 spin_unlock(&fs->lock);
888 tsk->fs = copy_fs_struct(fs);
894 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
896 struct files_struct *oldf, *newf;
900 * A background process may not have any files ...
902 oldf = current->files;
906 if (clone_flags & CLONE_FILES) {
907 atomic_inc(&oldf->count);
911 newf = dup_fd(oldf, &error);
921 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
924 struct io_context *ioc = current->io_context;
925 struct io_context *new_ioc;
930 * Share io context with parent, if CLONE_IO is set
932 if (clone_flags & CLONE_IO) {
933 tsk->io_context = ioc_task_link(ioc);
934 if (unlikely(!tsk->io_context))
936 } else if (ioprio_valid(ioc->ioprio)) {
937 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
938 if (unlikely(!new_ioc))
941 new_ioc->ioprio = ioc->ioprio;
942 put_io_context(new_ioc);
948 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
950 struct sighand_struct *sig;
952 if (clone_flags & CLONE_SIGHAND) {
953 atomic_inc(¤t->sighand->count);
956 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
957 rcu_assign_pointer(tsk->sighand, sig);
960 atomic_set(&sig->count, 1);
961 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
965 void __cleanup_sighand(struct sighand_struct *sighand)
967 if (atomic_dec_and_test(&sighand->count)) {
968 signalfd_cleanup(sighand);
969 kmem_cache_free(sighand_cachep, sighand);
975 * Initialize POSIX timer handling for a thread group.
977 static void posix_cpu_timers_init_group(struct signal_struct *sig)
979 unsigned long cpu_limit;
981 /* Thread group counters. */
982 thread_group_cputime_init(sig);
984 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
985 if (cpu_limit != RLIM_INFINITY) {
986 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
987 sig->cputimer.running = 1;
990 /* The timer lists. */
991 INIT_LIST_HEAD(&sig->cpu_timers[0]);
992 INIT_LIST_HEAD(&sig->cpu_timers[1]);
993 INIT_LIST_HEAD(&sig->cpu_timers[2]);
996 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
998 struct signal_struct *sig;
1000 if (clone_flags & CLONE_THREAD)
1003 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1008 sig->nr_threads = 1;
1009 atomic_set(&sig->live, 1);
1010 atomic_set(&sig->sigcnt, 1);
1011 init_waitqueue_head(&sig->wait_chldexit);
1012 if (clone_flags & CLONE_NEWPID)
1013 sig->flags |= SIGNAL_UNKILLABLE;
1014 sig->curr_target = tsk;
1015 init_sigpending(&sig->shared_pending);
1016 INIT_LIST_HEAD(&sig->posix_timers);
1018 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1019 sig->real_timer.function = it_real_fn;
1021 task_lock(current->group_leader);
1022 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1023 task_unlock(current->group_leader);
1025 posix_cpu_timers_init_group(sig);
1027 tty_audit_fork(sig);
1028 sched_autogroup_fork(sig);
1030 #ifdef CONFIG_CGROUPS
1031 init_rwsem(&sig->group_rwsem);
1034 sig->oom_adj = current->signal->oom_adj;
1035 sig->oom_score_adj = current->signal->oom_score_adj;
1036 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1038 mutex_init(&sig->cred_guard_mutex);
1043 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
1045 unsigned long new_flags = p->flags;
1047 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
1048 new_flags |= PF_FORKNOEXEC;
1049 new_flags |= PF_STARTING;
1050 p->flags = new_flags;
1053 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1055 current->clear_child_tid = tidptr;
1057 return task_pid_vnr(current);
1060 static void rt_mutex_init_task(struct task_struct *p)
1062 raw_spin_lock_init(&p->pi_lock);
1063 #ifdef CONFIG_RT_MUTEXES
1064 plist_head_init(&p->pi_waiters);
1065 p->pi_blocked_on = NULL;
1069 #ifdef CONFIG_MM_OWNER
1070 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1074 #endif /* CONFIG_MM_OWNER */
1077 * Initialize POSIX timer handling for a single task.
1079 static void posix_cpu_timers_init(struct task_struct *tsk)
1081 tsk->cputime_expires.prof_exp = 0;
1082 tsk->cputime_expires.virt_exp = 0;
1083 tsk->cputime_expires.sched_exp = 0;
1084 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1085 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1086 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1090 * This creates a new process as a copy of the old one,
1091 * but does not actually start it yet.
1093 * It copies the registers, and all the appropriate
1094 * parts of the process environment (as per the clone
1095 * flags). The actual kick-off is left to the caller.
1097 static struct task_struct *copy_process(unsigned long clone_flags,
1098 unsigned long stack_start,
1099 struct pt_regs *regs,
1100 unsigned long stack_size,
1101 int __user *child_tidptr,
1106 struct task_struct *p;
1107 int cgroup_callbacks_done = 0;
1109 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1110 return ERR_PTR(-EINVAL);
1113 * Thread groups must share signals as well, and detached threads
1114 * can only be started up within the thread group.
1116 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1117 return ERR_PTR(-EINVAL);
1120 * Shared signal handlers imply shared VM. By way of the above,
1121 * thread groups also imply shared VM. Blocking this case allows
1122 * for various simplifications in other code.
1124 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1125 return ERR_PTR(-EINVAL);
1128 * Siblings of global init remain as zombies on exit since they are
1129 * not reaped by their parent (swapper). To solve this and to avoid
1130 * multi-rooted process trees, prevent global and container-inits
1131 * from creating siblings.
1133 if ((clone_flags & CLONE_PARENT) &&
1134 current->signal->flags & SIGNAL_UNKILLABLE)
1135 return ERR_PTR(-EINVAL);
1137 retval = security_task_create(clone_flags);
1142 p = dup_task_struct(current);
1146 ftrace_graph_init_task(p);
1148 rt_mutex_init_task(p);
1150 #ifdef CONFIG_PROVE_LOCKING
1151 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1152 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1155 if (atomic_read(&p->real_cred->user->processes) >=
1156 task_rlimit(p, RLIMIT_NPROC)) {
1157 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1158 p->real_cred->user != INIT_USER)
1161 current->flags &= ~PF_NPROC_EXCEEDED;
1163 retval = copy_creds(p, clone_flags);
1168 * If multiple threads are within copy_process(), then this check
1169 * triggers too late. This doesn't hurt, the check is only there
1170 * to stop root fork bombs.
1173 if (nr_threads >= max_threads)
1174 goto bad_fork_cleanup_count;
1176 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1177 goto bad_fork_cleanup_count;
1180 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1181 copy_flags(clone_flags, p);
1182 INIT_LIST_HEAD(&p->children);
1183 INIT_LIST_HEAD(&p->sibling);
1184 rcu_copy_process(p);
1185 p->vfork_done = NULL;
1186 spin_lock_init(&p->alloc_lock);
1188 init_sigpending(&p->pending);
1190 p->utime = p->stime = p->gtime = 0;
1191 p->utimescaled = p->stimescaled = 0;
1192 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1193 p->prev_utime = p->prev_stime = 0;
1195 #if defined(SPLIT_RSS_COUNTING)
1196 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1199 p->default_timer_slack_ns = current->timer_slack_ns;
1201 task_io_accounting_init(&p->ioac);
1202 acct_clear_integrals(p);
1204 posix_cpu_timers_init(p);
1206 do_posix_clock_monotonic_gettime(&p->start_time);
1207 p->real_start_time = p->start_time;
1208 monotonic_to_bootbased(&p->real_start_time);
1209 p->io_context = NULL;
1210 p->audit_context = NULL;
1211 if (clone_flags & CLONE_THREAD)
1212 threadgroup_change_begin(current);
1215 p->mempolicy = mpol_dup(p->mempolicy);
1216 if (IS_ERR(p->mempolicy)) {
1217 retval = PTR_ERR(p->mempolicy);
1218 p->mempolicy = NULL;
1219 goto bad_fork_cleanup_cgroup;
1221 mpol_fix_fork_child_flag(p);
1223 #ifdef CONFIG_CPUSETS
1224 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1225 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1227 #ifdef CONFIG_TRACE_IRQFLAGS
1229 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1230 p->hardirqs_enabled = 1;
1232 p->hardirqs_enabled = 0;
1234 p->hardirq_enable_ip = 0;
1235 p->hardirq_enable_event = 0;
1236 p->hardirq_disable_ip = _THIS_IP_;
1237 p->hardirq_disable_event = 0;
1238 p->softirqs_enabled = 1;
1239 p->softirq_enable_ip = _THIS_IP_;
1240 p->softirq_enable_event = 0;
1241 p->softirq_disable_ip = 0;
1242 p->softirq_disable_event = 0;
1243 p->hardirq_context = 0;
1244 p->softirq_context = 0;
1246 #ifdef CONFIG_LOCKDEP
1247 p->lockdep_depth = 0; /* no locks held yet */
1248 p->curr_chain_key = 0;
1249 p->lockdep_recursion = 0;
1252 #ifdef CONFIG_DEBUG_MUTEXES
1253 p->blocked_on = NULL; /* not blocked yet */
1255 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1256 p->memcg_batch.do_batch = 0;
1257 p->memcg_batch.memcg = NULL;
1260 /* Perform scheduler related setup. Assign this task to a CPU. */
1263 retval = perf_event_init_task(p);
1265 goto bad_fork_cleanup_policy;
1266 retval = audit_alloc(p);
1268 goto bad_fork_cleanup_policy;
1269 /* copy all the process information */
1270 retval = copy_semundo(clone_flags, p);
1272 goto bad_fork_cleanup_audit;
1273 retval = copy_files(clone_flags, p);
1275 goto bad_fork_cleanup_semundo;
1276 retval = copy_fs(clone_flags, p);
1278 goto bad_fork_cleanup_files;
1279 retval = copy_sighand(clone_flags, p);
1281 goto bad_fork_cleanup_fs;
1282 retval = copy_signal(clone_flags, p);
1284 goto bad_fork_cleanup_sighand;
1285 retval = copy_mm(clone_flags, p);
1287 goto bad_fork_cleanup_signal;
1288 retval = copy_namespaces(clone_flags, p);
1290 goto bad_fork_cleanup_mm;
1291 retval = copy_io(clone_flags, p);
1293 goto bad_fork_cleanup_namespaces;
1294 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1296 goto bad_fork_cleanup_io;
1298 if (pid != &init_struct_pid) {
1300 pid = alloc_pid(p->nsproxy->pid_ns);
1302 goto bad_fork_cleanup_io;
1305 p->pid = pid_nr(pid);
1307 if (clone_flags & CLONE_THREAD)
1308 p->tgid = current->tgid;
1310 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1312 * Clear TID on mm_release()?
1314 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1319 p->robust_list = NULL;
1320 #ifdef CONFIG_COMPAT
1321 p->compat_robust_list = NULL;
1323 INIT_LIST_HEAD(&p->pi_state_list);
1324 p->pi_state_cache = NULL;
1327 * sigaltstack should be cleared when sharing the same VM
1329 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1330 p->sas_ss_sp = p->sas_ss_size = 0;
1333 * Syscall tracing and stepping should be turned off in the
1334 * child regardless of CLONE_PTRACE.
1336 user_disable_single_step(p);
1337 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1338 #ifdef TIF_SYSCALL_EMU
1339 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1341 clear_all_latency_tracing(p);
1343 /* ok, now we should be set up.. */
1344 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1345 p->pdeath_signal = 0;
1349 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1350 p->dirty_paused_when = 0;
1353 * Ok, make it visible to the rest of the system.
1354 * We dont wake it up yet.
1356 p->group_leader = p;
1357 INIT_LIST_HEAD(&p->thread_group);
1359 /* Now that the task is set up, run cgroup callbacks if
1360 * necessary. We need to run them before the task is visible
1361 * on the tasklist. */
1362 cgroup_fork_callbacks(p);
1363 cgroup_callbacks_done = 1;
1365 /* Need tasklist lock for parent etc handling! */
1366 write_lock_irq(&tasklist_lock);
1368 /* CLONE_PARENT re-uses the old parent */
1369 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1370 p->real_parent = current->real_parent;
1371 p->parent_exec_id = current->parent_exec_id;
1373 p->real_parent = current;
1374 p->parent_exec_id = current->self_exec_id;
1377 spin_lock(¤t->sighand->siglock);
1380 * Process group and session signals need to be delivered to just the
1381 * parent before the fork or both the parent and the child after the
1382 * fork. Restart if a signal comes in before we add the new process to
1383 * it's process group.
1384 * A fatal signal pending means that current will exit, so the new
1385 * thread can't slip out of an OOM kill (or normal SIGKILL).
1387 recalc_sigpending();
1388 if (signal_pending(current)) {
1389 spin_unlock(¤t->sighand->siglock);
1390 write_unlock_irq(&tasklist_lock);
1391 retval = -ERESTARTNOINTR;
1392 goto bad_fork_free_pid;
1395 if (clone_flags & CLONE_THREAD) {
1396 current->signal->nr_threads++;
1397 atomic_inc(¤t->signal->live);
1398 atomic_inc(¤t->signal->sigcnt);
1399 p->group_leader = current->group_leader;
1400 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1403 if (likely(p->pid)) {
1404 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
1406 if (thread_group_leader(p)) {
1407 if (is_child_reaper(pid))
1408 p->nsproxy->pid_ns->child_reaper = p;
1410 p->signal->leader_pid = pid;
1411 p->signal->tty = tty_kref_get(current->signal->tty);
1412 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1413 attach_pid(p, PIDTYPE_SID, task_session(current));
1414 list_add_tail(&p->sibling, &p->real_parent->children);
1415 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1416 __this_cpu_inc(process_counts);
1418 attach_pid(p, PIDTYPE_PID, pid);
1423 spin_unlock(¤t->sighand->siglock);
1424 write_unlock_irq(&tasklist_lock);
1425 proc_fork_connector(p);
1426 cgroup_post_fork(p);
1427 if (clone_flags & CLONE_THREAD)
1428 threadgroup_change_end(current);
1431 trace_task_newtask(p, clone_flags);
1436 if (pid != &init_struct_pid)
1438 bad_fork_cleanup_io:
1441 bad_fork_cleanup_namespaces:
1442 exit_task_namespaces(p);
1443 bad_fork_cleanup_mm:
1446 bad_fork_cleanup_signal:
1447 if (!(clone_flags & CLONE_THREAD))
1448 free_signal_struct(p->signal);
1449 bad_fork_cleanup_sighand:
1450 __cleanup_sighand(p->sighand);
1451 bad_fork_cleanup_fs:
1452 exit_fs(p); /* blocking */
1453 bad_fork_cleanup_files:
1454 exit_files(p); /* blocking */
1455 bad_fork_cleanup_semundo:
1457 bad_fork_cleanup_audit:
1459 bad_fork_cleanup_policy:
1460 perf_event_free_task(p);
1462 mpol_put(p->mempolicy);
1463 bad_fork_cleanup_cgroup:
1465 if (clone_flags & CLONE_THREAD)
1466 threadgroup_change_end(current);
1467 cgroup_exit(p, cgroup_callbacks_done);
1468 delayacct_tsk_free(p);
1469 module_put(task_thread_info(p)->exec_domain->module);
1470 bad_fork_cleanup_count:
1471 atomic_dec(&p->cred->user->processes);
1476 return ERR_PTR(retval);
1479 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1481 memset(regs, 0, sizeof(struct pt_regs));
1485 static inline void init_idle_pids(struct pid_link *links)
1489 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1490 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1491 links[type].pid = &init_struct_pid;
1495 struct task_struct * __cpuinit fork_idle(int cpu)
1497 struct task_struct *task;
1498 struct pt_regs regs;
1500 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1501 &init_struct_pid, 0);
1502 if (!IS_ERR(task)) {
1503 init_idle_pids(task->pids);
1504 init_idle(task, cpu);
1511 * Ok, this is the main fork-routine.
1513 * It copies the process, and if successful kick-starts
1514 * it and waits for it to finish using the VM if required.
1516 long do_fork(unsigned long clone_flags,
1517 unsigned long stack_start,
1518 struct pt_regs *regs,
1519 unsigned long stack_size,
1520 int __user *parent_tidptr,
1521 int __user *child_tidptr)
1523 struct task_struct *p;
1528 * Do some preliminary argument and permissions checking before we
1529 * actually start allocating stuff
1531 if (clone_flags & CLONE_NEWUSER) {
1532 if (clone_flags & CLONE_THREAD)
1534 /* hopefully this check will go away when userns support is
1537 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1538 !capable(CAP_SETGID))
1543 * Determine whether and which event to report to ptracer. When
1544 * called from kernel_thread or CLONE_UNTRACED is explicitly
1545 * requested, no event is reported; otherwise, report if the event
1546 * for the type of forking is enabled.
1548 if (likely(user_mode(regs)) && !(clone_flags & CLONE_UNTRACED)) {
1549 if (clone_flags & CLONE_VFORK)
1550 trace = PTRACE_EVENT_VFORK;
1551 else if ((clone_flags & CSIGNAL) != SIGCHLD)
1552 trace = PTRACE_EVENT_CLONE;
1554 trace = PTRACE_EVENT_FORK;
1556 if (likely(!ptrace_event_enabled(current, trace)))
1560 p = copy_process(clone_flags, stack_start, regs, stack_size,
1561 child_tidptr, NULL, trace);
1563 * Do this prior waking up the new thread - the thread pointer
1564 * might get invalid after that point, if the thread exits quickly.
1567 struct completion vfork;
1569 trace_sched_process_fork(current, p);
1571 nr = task_pid_vnr(p);
1573 if (clone_flags & CLONE_PARENT_SETTID)
1574 put_user(nr, parent_tidptr);
1576 if (clone_flags & CLONE_VFORK) {
1577 p->vfork_done = &vfork;
1578 init_completion(&vfork);
1583 * We set PF_STARTING at creation in case tracing wants to
1584 * use this to distinguish a fully live task from one that
1585 * hasn't finished SIGSTOP raising yet. Now we clear it
1586 * and set the child going.
1588 p->flags &= ~PF_STARTING;
1590 wake_up_new_task(p);
1592 /* forking complete and child started to run, tell ptracer */
1593 if (unlikely(trace))
1594 ptrace_event(trace, nr);
1596 if (clone_flags & CLONE_VFORK) {
1597 if (!wait_for_vfork_done(p, &vfork))
1598 ptrace_event(PTRACE_EVENT_VFORK_DONE, nr);
1606 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1607 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1610 static void sighand_ctor(void *data)
1612 struct sighand_struct *sighand = data;
1614 spin_lock_init(&sighand->siglock);
1615 init_waitqueue_head(&sighand->signalfd_wqh);
1618 void __init proc_caches_init(void)
1620 sighand_cachep = kmem_cache_create("sighand_cache",
1621 sizeof(struct sighand_struct), 0,
1622 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1623 SLAB_NOTRACK, sighand_ctor);
1624 signal_cachep = kmem_cache_create("signal_cache",
1625 sizeof(struct signal_struct), 0,
1626 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1627 files_cachep = kmem_cache_create("files_cache",
1628 sizeof(struct files_struct), 0,
1629 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1630 fs_cachep = kmem_cache_create("fs_cache",
1631 sizeof(struct fs_struct), 0,
1632 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1634 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1635 * whole struct cpumask for the OFFSTACK case. We could change
1636 * this to *only* allocate as much of it as required by the
1637 * maximum number of CPU's we can ever have. The cpumask_allocation
1638 * is at the end of the structure, exactly for that reason.
1640 mm_cachep = kmem_cache_create("mm_struct",
1641 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1642 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1643 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1645 nsproxy_cache_init();
1649 * Check constraints on flags passed to the unshare system call.
1651 static int check_unshare_flags(unsigned long unshare_flags)
1653 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1654 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1655 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1658 * Not implemented, but pretend it works if there is nothing to
1659 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1660 * needs to unshare vm.
1662 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1663 /* FIXME: get_task_mm() increments ->mm_users */
1664 if (atomic_read(¤t->mm->mm_users) > 1)
1672 * Unshare the filesystem structure if it is being shared
1674 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1676 struct fs_struct *fs = current->fs;
1678 if (!(unshare_flags & CLONE_FS) || !fs)
1681 /* don't need lock here; in the worst case we'll do useless copy */
1685 *new_fsp = copy_fs_struct(fs);
1693 * Unshare file descriptor table if it is being shared
1695 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1697 struct files_struct *fd = current->files;
1700 if ((unshare_flags & CLONE_FILES) &&
1701 (fd && atomic_read(&fd->count) > 1)) {
1702 *new_fdp = dup_fd(fd, &error);
1711 * unshare allows a process to 'unshare' part of the process
1712 * context which was originally shared using clone. copy_*
1713 * functions used by do_fork() cannot be used here directly
1714 * because they modify an inactive task_struct that is being
1715 * constructed. Here we are modifying the current, active,
1718 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1720 struct fs_struct *fs, *new_fs = NULL;
1721 struct files_struct *fd, *new_fd = NULL;
1722 struct nsproxy *new_nsproxy = NULL;
1726 err = check_unshare_flags(unshare_flags);
1728 goto bad_unshare_out;
1731 * If unsharing namespace, must also unshare filesystem information.
1733 if (unshare_flags & CLONE_NEWNS)
1734 unshare_flags |= CLONE_FS;
1736 * CLONE_NEWIPC must also detach from the undolist: after switching
1737 * to a new ipc namespace, the semaphore arrays from the old
1738 * namespace are unreachable.
1740 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1742 err = unshare_fs(unshare_flags, &new_fs);
1744 goto bad_unshare_out;
1745 err = unshare_fd(unshare_flags, &new_fd);
1747 goto bad_unshare_cleanup_fs;
1748 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy, new_fs);
1750 goto bad_unshare_cleanup_fd;
1752 if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
1755 * CLONE_SYSVSEM is equivalent to sys_exit().
1761 switch_task_namespaces(current, new_nsproxy);
1769 spin_lock(&fs->lock);
1770 current->fs = new_fs;
1775 spin_unlock(&fs->lock);
1779 fd = current->files;
1780 current->files = new_fd;
1784 task_unlock(current);
1788 put_nsproxy(new_nsproxy);
1790 bad_unshare_cleanup_fd:
1792 put_files_struct(new_fd);
1794 bad_unshare_cleanup_fs:
1796 free_fs_struct(new_fs);
1803 * Helper to unshare the files of the current task.
1804 * We don't want to expose copy_files internals to
1805 * the exec layer of the kernel.
1808 int unshare_files(struct files_struct **displaced)
1810 struct task_struct *task = current;
1811 struct files_struct *copy = NULL;
1814 error = unshare_fd(CLONE_FILES, ©);
1815 if (error || !copy) {
1819 *displaced = task->files;