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/proc_fs.h>
63 #include <linux/blkdev.h>
64 #include <linux/fs_struct.h>
65 #include <linux/magic.h>
66 #include <linux/perf_event.h>
67 #include <linux/posix-timers.h>
68 #include <linux/user-return-notifier.h>
69 #include <linux/oom.h>
70 #include <linux/khugepaged.h>
72 #include <asm/pgtable.h>
73 #include <asm/pgalloc.h>
74 #include <asm/uaccess.h>
75 #include <asm/mmu_context.h>
76 #include <asm/cacheflush.h>
77 #include <asm/tlbflush.h>
79 #include <trace/events/sched.h>
82 * Protected counters by write_lock_irq(&tasklist_lock)
84 unsigned long total_forks
; /* Handle normal Linux uptimes. */
85 int nr_threads
; /* The idle threads do not count.. */
87 int max_threads
; /* tunable limit on nr_threads */
89 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
91 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
93 #ifdef CONFIG_PROVE_RCU
94 int lockdep_tasklist_lock_is_held(void)
96 return lockdep_is_held(&tasklist_lock
);
98 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
99 #endif /* #ifdef CONFIG_PROVE_RCU */
101 int nr_processes(void)
106 for_each_possible_cpu(cpu
)
107 total
+= per_cpu(process_counts
, cpu
);
112 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
113 # define alloc_task_struct_node(node) \
114 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
115 # define free_task_struct(tsk) \
116 kmem_cache_free(task_struct_cachep, (tsk))
117 static struct kmem_cache
*task_struct_cachep
;
120 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
121 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
124 #ifdef CONFIG_DEBUG_STACK_USAGE
125 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
127 gfp_t mask
= GFP_KERNEL
;
129 struct page
*page
= alloc_pages_node(node
, mask
, THREAD_SIZE_ORDER
);
131 return page
? page_address(page
) : NULL
;
134 static inline void free_thread_info(struct thread_info
*ti
)
136 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
140 /* SLAB cache for signal_struct structures (tsk->signal) */
141 static struct kmem_cache
*signal_cachep
;
143 /* SLAB cache for sighand_struct structures (tsk->sighand) */
144 struct kmem_cache
*sighand_cachep
;
146 /* SLAB cache for files_struct structures (tsk->files) */
147 struct kmem_cache
*files_cachep
;
149 /* SLAB cache for fs_struct structures (tsk->fs) */
150 struct kmem_cache
*fs_cachep
;
152 /* SLAB cache for vm_area_struct structures */
153 struct kmem_cache
*vm_area_cachep
;
155 /* SLAB cache for mm_struct structures (tsk->mm) */
156 static struct kmem_cache
*mm_cachep
;
158 static void account_kernel_stack(struct thread_info
*ti
, int account
)
160 struct zone
*zone
= page_zone(virt_to_page(ti
));
162 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
165 void free_task(struct task_struct
*tsk
)
167 prop_local_destroy_single(&tsk
->dirties
);
168 account_kernel_stack(tsk
->stack
, -1);
169 free_thread_info(tsk
->stack
);
170 rt_mutex_debug_task_free(tsk
);
171 ftrace_graph_exit_task(tsk
);
172 free_task_struct(tsk
);
174 EXPORT_SYMBOL(free_task
);
176 static inline void free_signal_struct(struct signal_struct
*sig
)
178 taskstats_tgid_free(sig
);
179 sched_autogroup_exit(sig
);
180 kmem_cache_free(signal_cachep
, sig
);
183 static inline void put_signal_struct(struct signal_struct
*sig
)
185 if (atomic_dec_and_test(&sig
->sigcnt
))
186 free_signal_struct(sig
);
189 void __put_task_struct(struct task_struct
*tsk
)
191 WARN_ON(!tsk
->exit_state
);
192 WARN_ON(atomic_read(&tsk
->usage
));
193 WARN_ON(tsk
== current
);
196 delayacct_tsk_free(tsk
);
197 put_signal_struct(tsk
->signal
);
199 if (!profile_handoff_task(tsk
))
202 EXPORT_SYMBOL_GPL(__put_task_struct
);
205 * macro override instead of weak attribute alias, to workaround
206 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
208 #ifndef arch_task_cache_init
209 #define arch_task_cache_init()
212 void __init
fork_init(unsigned long mempages
)
214 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
215 #ifndef ARCH_MIN_TASKALIGN
216 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
218 /* create a slab on which task_structs can be allocated */
220 kmem_cache_create("task_struct", sizeof(struct task_struct
),
221 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
224 /* do the arch specific task caches init */
225 arch_task_cache_init();
228 * The default maximum number of threads is set to a safe
229 * value: the thread structures can take up at most half
232 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
235 * we need to allow at least 20 threads to boot a system
240 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
241 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
242 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
243 init_task
.signal
->rlim
[RLIMIT_NPROC
];
246 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
247 struct task_struct
*src
)
253 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
255 struct task_struct
*tsk
;
256 struct thread_info
*ti
;
257 unsigned long *stackend
;
258 int node
= tsk_fork_get_node(orig
);
261 prepare_to_copy(orig
);
263 tsk
= alloc_task_struct_node(node
);
267 ti
= alloc_thread_info_node(tsk
, node
);
269 free_task_struct(tsk
);
273 err
= arch_dup_task_struct(tsk
, orig
);
279 err
= prop_local_init_single(&tsk
->dirties
);
283 setup_thread_stack(tsk
, orig
);
284 clear_user_return_notifier(tsk
);
285 clear_tsk_need_resched(tsk
);
286 stackend
= end_of_stack(tsk
);
287 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
289 #ifdef CONFIG_CC_STACKPROTECTOR
290 tsk
->stack_canary
= get_random_int();
293 /* One for us, one for whoever does the "release_task()" (usually parent) */
294 atomic_set(&tsk
->usage
,2);
295 atomic_set(&tsk
->fs_excl
, 0);
296 #ifdef CONFIG_BLK_DEV_IO_TRACE
299 tsk
->splice_pipe
= NULL
;
301 account_kernel_stack(ti
, 1);
306 free_thread_info(ti
);
307 free_task_struct(tsk
);
312 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
314 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
315 struct rb_node
**rb_link
, *rb_parent
;
317 unsigned long charge
;
318 struct mempolicy
*pol
;
320 down_write(&oldmm
->mmap_sem
);
321 flush_cache_dup_mm(oldmm
);
323 * Not linked in yet - no deadlock potential:
325 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
329 mm
->mmap_cache
= NULL
;
330 mm
->free_area_cache
= oldmm
->mmap_base
;
331 mm
->cached_hole_size
= ~0UL;
333 cpumask_clear(mm_cpumask(mm
));
335 rb_link
= &mm
->mm_rb
.rb_node
;
338 retval
= ksm_fork(mm
, oldmm
);
341 retval
= khugepaged_fork(mm
, oldmm
);
346 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
349 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
350 long pages
= vma_pages(mpnt
);
351 mm
->total_vm
-= pages
;
352 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
357 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
358 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
359 if (security_vm_enough_memory(len
))
363 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
367 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
368 pol
= mpol_dup(vma_policy(mpnt
));
369 retval
= PTR_ERR(pol
);
371 goto fail_nomem_policy
;
372 vma_set_policy(tmp
, pol
);
374 if (anon_vma_fork(tmp
, mpnt
))
375 goto fail_nomem_anon_vma_fork
;
376 tmp
->vm_flags
&= ~VM_LOCKED
;
377 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
380 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
381 struct address_space
*mapping
= file
->f_mapping
;
384 if (tmp
->vm_flags
& VM_DENYWRITE
)
385 atomic_dec(&inode
->i_writecount
);
386 mutex_lock(&mapping
->i_mmap_mutex
);
387 if (tmp
->vm_flags
& VM_SHARED
)
388 mapping
->i_mmap_writable
++;
389 flush_dcache_mmap_lock(mapping
);
390 /* insert tmp into the share list, just after mpnt */
391 vma_prio_tree_add(tmp
, mpnt
);
392 flush_dcache_mmap_unlock(mapping
);
393 mutex_unlock(&mapping
->i_mmap_mutex
);
397 * Clear hugetlb-related page reserves for children. This only
398 * affects MAP_PRIVATE mappings. Faults generated by the child
399 * are not guaranteed to succeed, even if read-only
401 if (is_vm_hugetlb_page(tmp
))
402 reset_vma_resv_huge_pages(tmp
);
405 * Link in the new vma and copy the page table entries.
408 pprev
= &tmp
->vm_next
;
412 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
413 rb_link
= &tmp
->vm_rb
.rb_right
;
414 rb_parent
= &tmp
->vm_rb
;
417 retval
= copy_page_range(mm
, oldmm
, mpnt
);
419 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
420 tmp
->vm_ops
->open(tmp
);
425 /* a new mm has just been created */
426 arch_dup_mmap(oldmm
, mm
);
429 up_write(&mm
->mmap_sem
);
431 up_write(&oldmm
->mmap_sem
);
433 fail_nomem_anon_vma_fork
:
436 kmem_cache_free(vm_area_cachep
, tmp
);
439 vm_unacct_memory(charge
);
443 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
445 mm
->pgd
= pgd_alloc(mm
);
446 if (unlikely(!mm
->pgd
))
451 static inline void mm_free_pgd(struct mm_struct
* mm
)
453 pgd_free(mm
, mm
->pgd
);
456 #define dup_mmap(mm, oldmm) (0)
457 #define mm_alloc_pgd(mm) (0)
458 #define mm_free_pgd(mm)
459 #endif /* CONFIG_MMU */
461 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
463 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
464 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
466 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
468 static int __init
coredump_filter_setup(char *s
)
470 default_dump_filter
=
471 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
472 MMF_DUMP_FILTER_MASK
;
476 __setup("coredump_filter=", coredump_filter_setup
);
478 #include <linux/init_task.h>
480 static void mm_init_aio(struct mm_struct
*mm
)
483 spin_lock_init(&mm
->ioctx_lock
);
484 INIT_HLIST_HEAD(&mm
->ioctx_list
);
488 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
490 atomic_set(&mm
->mm_users
, 1);
491 atomic_set(&mm
->mm_count
, 1);
492 init_rwsem(&mm
->mmap_sem
);
493 INIT_LIST_HEAD(&mm
->mmlist
);
494 mm
->flags
= (current
->mm
) ?
495 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
496 mm
->core_state
= NULL
;
498 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
499 spin_lock_init(&mm
->page_table_lock
);
500 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
501 mm
->cached_hole_size
= ~0UL;
503 mm_init_owner(mm
, p
);
504 atomic_set(&mm
->oom_disable_count
, 0);
506 if (likely(!mm_alloc_pgd(mm
))) {
508 mmu_notifier_mm_init(mm
);
517 * Allocate and initialize an mm_struct.
519 struct mm_struct
* mm_alloc(void)
521 struct mm_struct
* mm
;
525 memset(mm
, 0, sizeof(*mm
));
526 mm
= mm_init(mm
, current
);
532 * Called when the last reference to the mm
533 * is dropped: either by a lazy thread or by
534 * mmput. Free the page directory and the mm.
536 void __mmdrop(struct mm_struct
*mm
)
538 BUG_ON(mm
== &init_mm
);
541 mmu_notifier_mm_destroy(mm
);
542 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
543 VM_BUG_ON(mm
->pmd_huge_pte
);
547 EXPORT_SYMBOL_GPL(__mmdrop
);
550 * Decrement the use count and release all resources for an mm.
552 void mmput(struct mm_struct
*mm
)
556 if (atomic_dec_and_test(&mm
->mm_users
)) {
559 khugepaged_exit(mm
); /* must run before exit_mmap */
561 set_mm_exe_file(mm
, NULL
);
562 if (!list_empty(&mm
->mmlist
)) {
563 spin_lock(&mmlist_lock
);
564 list_del(&mm
->mmlist
);
565 spin_unlock(&mmlist_lock
);
569 module_put(mm
->binfmt
->module
);
573 EXPORT_SYMBOL_GPL(mmput
);
576 * get_task_mm - acquire a reference to the task's mm
578 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
579 * this kernel workthread has transiently adopted a user mm with use_mm,
580 * to do its AIO) is not set and if so returns a reference to it, after
581 * bumping up the use count. User must release the mm via mmput()
582 * after use. Typically used by /proc and ptrace.
584 struct mm_struct
*get_task_mm(struct task_struct
*task
)
586 struct mm_struct
*mm
;
591 if (task
->flags
& PF_KTHREAD
)
594 atomic_inc(&mm
->mm_users
);
599 EXPORT_SYMBOL_GPL(get_task_mm
);
601 /* Please note the differences between mmput and mm_release.
602 * mmput is called whenever we stop holding onto a mm_struct,
603 * error success whatever.
605 * mm_release is called after a mm_struct has been removed
606 * from the current process.
608 * This difference is important for error handling, when we
609 * only half set up a mm_struct for a new process and need to restore
610 * the old one. Because we mmput the new mm_struct before
611 * restoring the old one. . .
612 * Eric Biederman 10 January 1998
614 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
616 struct completion
*vfork_done
= tsk
->vfork_done
;
618 /* Get rid of any futexes when releasing the mm */
620 if (unlikely(tsk
->robust_list
)) {
621 exit_robust_list(tsk
);
622 tsk
->robust_list
= NULL
;
625 if (unlikely(tsk
->compat_robust_list
)) {
626 compat_exit_robust_list(tsk
);
627 tsk
->compat_robust_list
= NULL
;
630 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
631 exit_pi_state_list(tsk
);
634 /* Get rid of any cached register state */
635 deactivate_mm(tsk
, mm
);
637 /* notify parent sleeping on vfork() */
639 tsk
->vfork_done
= NULL
;
640 complete(vfork_done
);
644 * If we're exiting normally, clear a user-space tid field if
645 * requested. We leave this alone when dying by signal, to leave
646 * the value intact in a core dump, and to save the unnecessary
647 * trouble otherwise. Userland only wants this done for a sys_exit.
649 if (tsk
->clear_child_tid
) {
650 if (!(tsk
->flags
& PF_SIGNALED
) &&
651 atomic_read(&mm
->mm_users
) > 1) {
653 * We don't check the error code - if userspace has
654 * not set up a proper pointer then tough luck.
656 put_user(0, tsk
->clear_child_tid
);
657 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
660 tsk
->clear_child_tid
= NULL
;
665 * Allocate a new mm structure and copy contents from the
666 * mm structure of the passed in task structure.
668 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
670 struct mm_struct
*mm
, *oldmm
= current
->mm
;
680 memcpy(mm
, oldmm
, sizeof(*mm
));
682 /* Initializing for Swap token stuff */
683 mm
->token_priority
= 0;
684 mm
->last_interval
= 0;
686 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
687 mm
->pmd_huge_pte
= NULL
;
690 if (!mm_init(mm
, tsk
))
693 if (init_new_context(tsk
, mm
))
696 dup_mm_exe_file(oldmm
, mm
);
698 err
= dup_mmap(mm
, oldmm
);
702 mm
->hiwater_rss
= get_mm_rss(mm
);
703 mm
->hiwater_vm
= mm
->total_vm
;
705 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
711 /* don't put binfmt in mmput, we haven't got module yet */
720 * If init_new_context() failed, we cannot use mmput() to free the mm
721 * because it calls destroy_context()
728 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
730 struct mm_struct
* mm
, *oldmm
;
733 tsk
->min_flt
= tsk
->maj_flt
= 0;
734 tsk
->nvcsw
= tsk
->nivcsw
= 0;
735 #ifdef CONFIG_DETECT_HUNG_TASK
736 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
740 tsk
->active_mm
= NULL
;
743 * Are we cloning a kernel thread?
745 * We need to steal a active VM for that..
751 if (clone_flags
& CLONE_VM
) {
752 atomic_inc(&oldmm
->mm_users
);
763 /* Initializing for Swap token stuff */
764 mm
->token_priority
= 0;
765 mm
->last_interval
= 0;
766 if (tsk
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
)
767 atomic_inc(&mm
->oom_disable_count
);
777 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
779 struct fs_struct
*fs
= current
->fs
;
780 if (clone_flags
& CLONE_FS
) {
781 /* tsk->fs is already what we want */
782 spin_lock(&fs
->lock
);
784 spin_unlock(&fs
->lock
);
788 spin_unlock(&fs
->lock
);
791 tsk
->fs
= copy_fs_struct(fs
);
797 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
799 struct files_struct
*oldf
, *newf
;
803 * A background process may not have any files ...
805 oldf
= current
->files
;
809 if (clone_flags
& CLONE_FILES
) {
810 atomic_inc(&oldf
->count
);
814 newf
= dup_fd(oldf
, &error
);
824 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
827 struct io_context
*ioc
= current
->io_context
;
832 * Share io context with parent, if CLONE_IO is set
834 if (clone_flags
& CLONE_IO
) {
835 tsk
->io_context
= ioc_task_link(ioc
);
836 if (unlikely(!tsk
->io_context
))
838 } else if (ioprio_valid(ioc
->ioprio
)) {
839 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
840 if (unlikely(!tsk
->io_context
))
843 tsk
->io_context
->ioprio
= ioc
->ioprio
;
849 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
851 struct sighand_struct
*sig
;
853 if (clone_flags
& CLONE_SIGHAND
) {
854 atomic_inc(¤t
->sighand
->count
);
857 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
858 rcu_assign_pointer(tsk
->sighand
, sig
);
861 atomic_set(&sig
->count
, 1);
862 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
866 void __cleanup_sighand(struct sighand_struct
*sighand
)
868 if (atomic_dec_and_test(&sighand
->count
))
869 kmem_cache_free(sighand_cachep
, sighand
);
874 * Initialize POSIX timer handling for a thread group.
876 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
878 unsigned long cpu_limit
;
880 /* Thread group counters. */
881 thread_group_cputime_init(sig
);
883 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
884 if (cpu_limit
!= RLIM_INFINITY
) {
885 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
886 sig
->cputimer
.running
= 1;
889 /* The timer lists. */
890 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
891 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
892 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
895 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
897 struct signal_struct
*sig
;
899 if (clone_flags
& CLONE_THREAD
)
902 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
908 atomic_set(&sig
->live
, 1);
909 atomic_set(&sig
->sigcnt
, 1);
910 init_waitqueue_head(&sig
->wait_chldexit
);
911 if (clone_flags
& CLONE_NEWPID
)
912 sig
->flags
|= SIGNAL_UNKILLABLE
;
913 sig
->curr_target
= tsk
;
914 init_sigpending(&sig
->shared_pending
);
915 INIT_LIST_HEAD(&sig
->posix_timers
);
917 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
918 sig
->real_timer
.function
= it_real_fn
;
920 task_lock(current
->group_leader
);
921 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
922 task_unlock(current
->group_leader
);
924 posix_cpu_timers_init_group(sig
);
927 sched_autogroup_fork(sig
);
929 sig
->oom_adj
= current
->signal
->oom_adj
;
930 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
931 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
933 mutex_init(&sig
->cred_guard_mutex
);
938 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
940 unsigned long new_flags
= p
->flags
;
942 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
943 new_flags
|= PF_FORKNOEXEC
;
944 new_flags
|= PF_STARTING
;
945 p
->flags
= new_flags
;
946 clear_freeze_flag(p
);
949 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
951 current
->clear_child_tid
= tidptr
;
953 return task_pid_vnr(current
);
956 static void rt_mutex_init_task(struct task_struct
*p
)
958 raw_spin_lock_init(&p
->pi_lock
);
959 #ifdef CONFIG_RT_MUTEXES
960 plist_head_init_raw(&p
->pi_waiters
, &p
->pi_lock
);
961 p
->pi_blocked_on
= NULL
;
965 #ifdef CONFIG_MM_OWNER
966 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
970 #endif /* CONFIG_MM_OWNER */
973 * Initialize POSIX timer handling for a single task.
975 static void posix_cpu_timers_init(struct task_struct
*tsk
)
977 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
978 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
979 tsk
->cputime_expires
.sched_exp
= 0;
980 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
981 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
982 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
986 * This creates a new process as a copy of the old one,
987 * but does not actually start it yet.
989 * It copies the registers, and all the appropriate
990 * parts of the process environment (as per the clone
991 * flags). The actual kick-off is left to the caller.
993 static struct task_struct
*copy_process(unsigned long clone_flags
,
994 unsigned long stack_start
,
995 struct pt_regs
*regs
,
996 unsigned long stack_size
,
997 int __user
*child_tidptr
,
1002 struct task_struct
*p
;
1003 int cgroup_callbacks_done
= 0;
1005 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1006 return ERR_PTR(-EINVAL
);
1009 * Thread groups must share signals as well, and detached threads
1010 * can only be started up within the thread group.
1012 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1013 return ERR_PTR(-EINVAL
);
1016 * Shared signal handlers imply shared VM. By way of the above,
1017 * thread groups also imply shared VM. Blocking this case allows
1018 * for various simplifications in other code.
1020 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1021 return ERR_PTR(-EINVAL
);
1024 * Siblings of global init remain as zombies on exit since they are
1025 * not reaped by their parent (swapper). To solve this and to avoid
1026 * multi-rooted process trees, prevent global and container-inits
1027 * from creating siblings.
1029 if ((clone_flags
& CLONE_PARENT
) &&
1030 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1031 return ERR_PTR(-EINVAL
);
1033 retval
= security_task_create(clone_flags
);
1038 p
= dup_task_struct(current
);
1042 ftrace_graph_init_task(p
);
1044 rt_mutex_init_task(p
);
1046 #ifdef CONFIG_PROVE_LOCKING
1047 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1048 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1051 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1052 task_rlimit(p
, RLIMIT_NPROC
)) {
1053 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1054 p
->real_cred
->user
!= INIT_USER
)
1058 retval
= copy_creds(p
, clone_flags
);
1063 * If multiple threads are within copy_process(), then this check
1064 * triggers too late. This doesn't hurt, the check is only there
1065 * to stop root fork bombs.
1068 if (nr_threads
>= max_threads
)
1069 goto bad_fork_cleanup_count
;
1071 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1072 goto bad_fork_cleanup_count
;
1075 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1076 copy_flags(clone_flags
, p
);
1077 INIT_LIST_HEAD(&p
->children
);
1078 INIT_LIST_HEAD(&p
->sibling
);
1079 rcu_copy_process(p
);
1080 p
->vfork_done
= NULL
;
1081 spin_lock_init(&p
->alloc_lock
);
1083 init_sigpending(&p
->pending
);
1085 p
->utime
= cputime_zero
;
1086 p
->stime
= cputime_zero
;
1087 p
->gtime
= cputime_zero
;
1088 p
->utimescaled
= cputime_zero
;
1089 p
->stimescaled
= cputime_zero
;
1090 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1091 p
->prev_utime
= cputime_zero
;
1092 p
->prev_stime
= cputime_zero
;
1094 #if defined(SPLIT_RSS_COUNTING)
1095 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1098 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1100 task_io_accounting_init(&p
->ioac
);
1101 acct_clear_integrals(p
);
1103 posix_cpu_timers_init(p
);
1105 do_posix_clock_monotonic_gettime(&p
->start_time
);
1106 p
->real_start_time
= p
->start_time
;
1107 monotonic_to_bootbased(&p
->real_start_time
);
1108 p
->io_context
= NULL
;
1109 p
->audit_context
= NULL
;
1112 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1113 if (IS_ERR(p
->mempolicy
)) {
1114 retval
= PTR_ERR(p
->mempolicy
);
1115 p
->mempolicy
= NULL
;
1116 goto bad_fork_cleanup_cgroup
;
1118 mpol_fix_fork_child_flag(p
);
1120 #ifdef CONFIG_TRACE_IRQFLAGS
1122 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1123 p
->hardirqs_enabled
= 1;
1125 p
->hardirqs_enabled
= 0;
1127 p
->hardirq_enable_ip
= 0;
1128 p
->hardirq_enable_event
= 0;
1129 p
->hardirq_disable_ip
= _THIS_IP_
;
1130 p
->hardirq_disable_event
= 0;
1131 p
->softirqs_enabled
= 1;
1132 p
->softirq_enable_ip
= _THIS_IP_
;
1133 p
->softirq_enable_event
= 0;
1134 p
->softirq_disable_ip
= 0;
1135 p
->softirq_disable_event
= 0;
1136 p
->hardirq_context
= 0;
1137 p
->softirq_context
= 0;
1139 #ifdef CONFIG_LOCKDEP
1140 p
->lockdep_depth
= 0; /* no locks held yet */
1141 p
->curr_chain_key
= 0;
1142 p
->lockdep_recursion
= 0;
1145 #ifdef CONFIG_DEBUG_MUTEXES
1146 p
->blocked_on
= NULL
; /* not blocked yet */
1148 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1149 p
->memcg_batch
.do_batch
= 0;
1150 p
->memcg_batch
.memcg
= NULL
;
1153 /* Perform scheduler related setup. Assign this task to a CPU. */
1156 retval
= perf_event_init_task(p
);
1158 goto bad_fork_cleanup_policy
;
1160 if ((retval
= audit_alloc(p
)))
1161 goto bad_fork_cleanup_policy
;
1162 /* copy all the process information */
1163 if ((retval
= copy_semundo(clone_flags
, p
)))
1164 goto bad_fork_cleanup_audit
;
1165 if ((retval
= copy_files(clone_flags
, p
)))
1166 goto bad_fork_cleanup_semundo
;
1167 if ((retval
= copy_fs(clone_flags
, p
)))
1168 goto bad_fork_cleanup_files
;
1169 if ((retval
= copy_sighand(clone_flags
, p
)))
1170 goto bad_fork_cleanup_fs
;
1171 if ((retval
= copy_signal(clone_flags
, p
)))
1172 goto bad_fork_cleanup_sighand
;
1173 if ((retval
= copy_mm(clone_flags
, p
)))
1174 goto bad_fork_cleanup_signal
;
1175 if ((retval
= copy_namespaces(clone_flags
, p
)))
1176 goto bad_fork_cleanup_mm
;
1177 if ((retval
= copy_io(clone_flags
, p
)))
1178 goto bad_fork_cleanup_namespaces
;
1179 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1181 goto bad_fork_cleanup_io
;
1183 if (pid
!= &init_struct_pid
) {
1185 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1187 goto bad_fork_cleanup_io
;
1190 p
->pid
= pid_nr(pid
);
1192 if (clone_flags
& CLONE_THREAD
)
1193 p
->tgid
= current
->tgid
;
1195 if (current
->nsproxy
!= p
->nsproxy
) {
1196 retval
= ns_cgroup_clone(p
, pid
);
1198 goto bad_fork_free_pid
;
1201 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1203 * Clear TID on mm_release()?
1205 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1210 p
->robust_list
= NULL
;
1211 #ifdef CONFIG_COMPAT
1212 p
->compat_robust_list
= NULL
;
1214 INIT_LIST_HEAD(&p
->pi_state_list
);
1215 p
->pi_state_cache
= NULL
;
1218 * sigaltstack should be cleared when sharing the same VM
1220 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1221 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1224 * Syscall tracing and stepping should be turned off in the
1225 * child regardless of CLONE_PTRACE.
1227 user_disable_single_step(p
);
1228 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1229 #ifdef TIF_SYSCALL_EMU
1230 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1232 clear_all_latency_tracing(p
);
1234 /* ok, now we should be set up.. */
1235 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1236 p
->pdeath_signal
= 0;
1240 * Ok, make it visible to the rest of the system.
1241 * We dont wake it up yet.
1243 p
->group_leader
= p
;
1244 INIT_LIST_HEAD(&p
->thread_group
);
1246 /* Now that the task is set up, run cgroup callbacks if
1247 * necessary. We need to run them before the task is visible
1248 * on the tasklist. */
1249 cgroup_fork_callbacks(p
);
1250 cgroup_callbacks_done
= 1;
1252 /* Need tasklist lock for parent etc handling! */
1253 write_lock_irq(&tasklist_lock
);
1255 /* CLONE_PARENT re-uses the old parent */
1256 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1257 p
->real_parent
= current
->real_parent
;
1258 p
->parent_exec_id
= current
->parent_exec_id
;
1260 p
->real_parent
= current
;
1261 p
->parent_exec_id
= current
->self_exec_id
;
1264 spin_lock(¤t
->sighand
->siglock
);
1267 * Process group and session signals need to be delivered to just the
1268 * parent before the fork or both the parent and the child after the
1269 * fork. Restart if a signal comes in before we add the new process to
1270 * it's process group.
1271 * A fatal signal pending means that current will exit, so the new
1272 * thread can't slip out of an OOM kill (or normal SIGKILL).
1274 recalc_sigpending();
1275 if (signal_pending(current
)) {
1276 spin_unlock(¤t
->sighand
->siglock
);
1277 write_unlock_irq(&tasklist_lock
);
1278 retval
= -ERESTARTNOINTR
;
1279 goto bad_fork_free_pid
;
1282 if (clone_flags
& CLONE_THREAD
) {
1283 current
->signal
->nr_threads
++;
1284 atomic_inc(¤t
->signal
->live
);
1285 atomic_inc(¤t
->signal
->sigcnt
);
1286 p
->group_leader
= current
->group_leader
;
1287 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1290 if (likely(p
->pid
)) {
1291 tracehook_finish_clone(p
, clone_flags
, trace
);
1293 if (thread_group_leader(p
)) {
1294 if (is_child_reaper(pid
))
1295 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1297 p
->signal
->leader_pid
= pid
;
1298 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1299 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1300 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1301 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1302 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1303 __this_cpu_inc(process_counts
);
1305 attach_pid(p
, PIDTYPE_PID
, pid
);
1310 spin_unlock(¤t
->sighand
->siglock
);
1311 write_unlock_irq(&tasklist_lock
);
1312 proc_fork_connector(p
);
1313 cgroup_post_fork(p
);
1318 if (pid
!= &init_struct_pid
)
1320 bad_fork_cleanup_io
:
1323 bad_fork_cleanup_namespaces
:
1324 exit_task_namespaces(p
);
1325 bad_fork_cleanup_mm
:
1328 if (p
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
)
1329 atomic_dec(&p
->mm
->oom_disable_count
);
1333 bad_fork_cleanup_signal
:
1334 if (!(clone_flags
& CLONE_THREAD
))
1335 free_signal_struct(p
->signal
);
1336 bad_fork_cleanup_sighand
:
1337 __cleanup_sighand(p
->sighand
);
1338 bad_fork_cleanup_fs
:
1339 exit_fs(p
); /* blocking */
1340 bad_fork_cleanup_files
:
1341 exit_files(p
); /* blocking */
1342 bad_fork_cleanup_semundo
:
1344 bad_fork_cleanup_audit
:
1346 bad_fork_cleanup_policy
:
1347 perf_event_free_task(p
);
1349 mpol_put(p
->mempolicy
);
1350 bad_fork_cleanup_cgroup
:
1352 cgroup_exit(p
, cgroup_callbacks_done
);
1353 delayacct_tsk_free(p
);
1354 module_put(task_thread_info(p
)->exec_domain
->module
);
1355 bad_fork_cleanup_count
:
1356 atomic_dec(&p
->cred
->user
->processes
);
1361 return ERR_PTR(retval
);
1364 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1366 memset(regs
, 0, sizeof(struct pt_regs
));
1370 static inline void init_idle_pids(struct pid_link
*links
)
1374 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1375 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1376 links
[type
].pid
= &init_struct_pid
;
1380 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1382 struct task_struct
*task
;
1383 struct pt_regs regs
;
1385 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1386 &init_struct_pid
, 0);
1387 if (!IS_ERR(task
)) {
1388 init_idle_pids(task
->pids
);
1389 init_idle(task
, cpu
);
1396 * Ok, this is the main fork-routine.
1398 * It copies the process, and if successful kick-starts
1399 * it and waits for it to finish using the VM if required.
1401 long do_fork(unsigned long clone_flags
,
1402 unsigned long stack_start
,
1403 struct pt_regs
*regs
,
1404 unsigned long stack_size
,
1405 int __user
*parent_tidptr
,
1406 int __user
*child_tidptr
)
1408 struct task_struct
*p
;
1413 * Do some preliminary argument and permissions checking before we
1414 * actually start allocating stuff
1416 if (clone_flags
& CLONE_NEWUSER
) {
1417 if (clone_flags
& CLONE_THREAD
)
1419 /* hopefully this check will go away when userns support is
1422 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1423 !capable(CAP_SETGID
))
1428 * When called from kernel_thread, don't do user tracing stuff.
1430 if (likely(user_mode(regs
)))
1431 trace
= tracehook_prepare_clone(clone_flags
);
1433 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1434 child_tidptr
, NULL
, trace
);
1436 * Do this prior waking up the new thread - the thread pointer
1437 * might get invalid after that point, if the thread exits quickly.
1440 struct completion vfork
;
1442 trace_sched_process_fork(current
, p
);
1444 nr
= task_pid_vnr(p
);
1446 if (clone_flags
& CLONE_PARENT_SETTID
)
1447 put_user(nr
, parent_tidptr
);
1449 if (clone_flags
& CLONE_VFORK
) {
1450 p
->vfork_done
= &vfork
;
1451 init_completion(&vfork
);
1454 audit_finish_fork(p
);
1455 tracehook_report_clone(regs
, clone_flags
, nr
, p
);
1458 * We set PF_STARTING at creation in case tracing wants to
1459 * use this to distinguish a fully live task from one that
1460 * hasn't gotten to tracehook_report_clone() yet. Now we
1461 * clear it and set the child going.
1463 p
->flags
&= ~PF_STARTING
;
1465 wake_up_new_task(p
);
1467 tracehook_report_clone_complete(trace
, regs
,
1468 clone_flags
, nr
, p
);
1470 if (clone_flags
& CLONE_VFORK
) {
1471 freezer_do_not_count();
1472 wait_for_completion(&vfork
);
1474 tracehook_report_vfork_done(p
, nr
);
1482 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1483 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1486 static void sighand_ctor(void *data
)
1488 struct sighand_struct
*sighand
= data
;
1490 spin_lock_init(&sighand
->siglock
);
1491 init_waitqueue_head(&sighand
->signalfd_wqh
);
1494 void __init
proc_caches_init(void)
1496 sighand_cachep
= kmem_cache_create("sighand_cache",
1497 sizeof(struct sighand_struct
), 0,
1498 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1499 SLAB_NOTRACK
, sighand_ctor
);
1500 signal_cachep
= kmem_cache_create("signal_cache",
1501 sizeof(struct signal_struct
), 0,
1502 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1503 files_cachep
= kmem_cache_create("files_cache",
1504 sizeof(struct files_struct
), 0,
1505 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1506 fs_cachep
= kmem_cache_create("fs_cache",
1507 sizeof(struct fs_struct
), 0,
1508 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1509 mm_cachep
= kmem_cache_create("mm_struct",
1510 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1511 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1512 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1517 * Check constraints on flags passed to the unshare system call.
1519 static int check_unshare_flags(unsigned long unshare_flags
)
1521 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1522 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1523 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
))
1526 * Not implemented, but pretend it works if there is nothing to
1527 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1528 * needs to unshare vm.
1530 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
1531 /* FIXME: get_task_mm() increments ->mm_users */
1532 if (atomic_read(¤t
->mm
->mm_users
) > 1)
1540 * Unshare the filesystem structure if it is being shared
1542 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1544 struct fs_struct
*fs
= current
->fs
;
1546 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1549 /* don't need lock here; in the worst case we'll do useless copy */
1553 *new_fsp
= copy_fs_struct(fs
);
1561 * Unshare file descriptor table if it is being shared
1563 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1565 struct files_struct
*fd
= current
->files
;
1568 if ((unshare_flags
& CLONE_FILES
) &&
1569 (fd
&& atomic_read(&fd
->count
) > 1)) {
1570 *new_fdp
= dup_fd(fd
, &error
);
1579 * unshare allows a process to 'unshare' part of the process
1580 * context which was originally shared using clone. copy_*
1581 * functions used by do_fork() cannot be used here directly
1582 * because they modify an inactive task_struct that is being
1583 * constructed. Here we are modifying the current, active,
1586 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1588 struct fs_struct
*fs
, *new_fs
= NULL
;
1589 struct files_struct
*fd
, *new_fd
= NULL
;
1590 struct nsproxy
*new_nsproxy
= NULL
;
1594 err
= check_unshare_flags(unshare_flags
);
1596 goto bad_unshare_out
;
1599 * If unsharing namespace, must also unshare filesystem information.
1601 if (unshare_flags
& CLONE_NEWNS
)
1602 unshare_flags
|= CLONE_FS
;
1604 * CLONE_NEWIPC must also detach from the undolist: after switching
1605 * to a new ipc namespace, the semaphore arrays from the old
1606 * namespace are unreachable.
1608 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1610 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1611 goto bad_unshare_out
;
1612 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1613 goto bad_unshare_cleanup_fs
;
1614 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1616 goto bad_unshare_cleanup_fd
;
1618 if (new_fs
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1621 * CLONE_SYSVSEM is equivalent to sys_exit().
1627 switch_task_namespaces(current
, new_nsproxy
);
1635 spin_lock(&fs
->lock
);
1636 current
->fs
= new_fs
;
1641 spin_unlock(&fs
->lock
);
1645 fd
= current
->files
;
1646 current
->files
= new_fd
;
1650 task_unlock(current
);
1654 put_nsproxy(new_nsproxy
);
1656 bad_unshare_cleanup_fd
:
1658 put_files_struct(new_fd
);
1660 bad_unshare_cleanup_fs
:
1662 free_fs_struct(new_fs
);
1669 * Helper to unshare the files of the current task.
1670 * We don't want to expose copy_files internals to
1671 * the exec layer of the kernel.
1674 int unshare_files(struct files_struct
**displaced
)
1676 struct task_struct
*task
= current
;
1677 struct files_struct
*copy
= NULL
;
1680 error
= unshare_fd(CLONE_FILES
, ©
);
1681 if (error
|| !copy
) {
1685 *displaced
= task
->files
;