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/mnt_namespace.h>
21 #include <linux/personality.h>
22 #include <linux/mempolicy.h>
23 #include <linux/sem.h>
24 #include <linux/file.h>
25 #include <linux/fdtable.h>
26 #include <linux/key.h>
27 #include <linux/binfmts.h>
28 #include <linux/mman.h>
30 #include <linux/nsproxy.h>
31 #include <linux/capability.h>
32 #include <linux/cpu.h>
33 #include <linux/cgroup.h>
34 #include <linux/security.h>
35 #include <linux/swap.h>
36 #include <linux/syscalls.h>
37 #include <linux/jiffies.h>
38 #include <linux/futex.h>
39 #include <linux/task_io_accounting_ops.h>
40 #include <linux/rcupdate.h>
41 #include <linux/ptrace.h>
42 #include <linux/mount.h>
43 #include <linux/audit.h>
44 #include <linux/memcontrol.h>
45 #include <linux/profile.h>
46 #include <linux/rmap.h>
47 #include <linux/acct.h>
48 #include <linux/tsacct_kern.h>
49 #include <linux/cn_proc.h>
50 #include <linux/freezer.h>
51 #include <linux/delayacct.h>
52 #include <linux/taskstats_kern.h>
53 #include <linux/random.h>
54 #include <linux/tty.h>
55 #include <linux/proc_fs.h>
56 #include <linux/blkdev.h>
57 #include <linux/magic.h>
59 #include <asm/pgtable.h>
60 #include <asm/pgalloc.h>
61 #include <asm/uaccess.h>
62 #include <asm/mmu_context.h>
63 #include <asm/cacheflush.h>
64 #include <asm/tlbflush.h>
67 * Protected counters by write_lock_irq(&tasklist_lock)
69 unsigned long total_forks
; /* Handle normal Linux uptimes. */
70 int nr_threads
; /* The idle threads do not count.. */
72 int max_threads
; /* tunable limit on nr_threads */
74 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
76 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
78 int nr_processes(void)
83 for_each_online_cpu(cpu
)
84 total
+= per_cpu(process_counts
, cpu
);
89 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
90 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
91 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
92 static struct kmem_cache
*task_struct_cachep
;
95 /* SLAB cache for signal_struct structures (tsk->signal) */
96 static struct kmem_cache
*signal_cachep
;
98 /* SLAB cache for sighand_struct structures (tsk->sighand) */
99 struct kmem_cache
*sighand_cachep
;
101 /* SLAB cache for files_struct structures (tsk->files) */
102 struct kmem_cache
*files_cachep
;
104 /* SLAB cache for fs_struct structures (tsk->fs) */
105 struct kmem_cache
*fs_cachep
;
107 /* SLAB cache for vm_area_struct structures */
108 struct kmem_cache
*vm_area_cachep
;
110 /* SLAB cache for mm_struct structures (tsk->mm) */
111 static struct kmem_cache
*mm_cachep
;
113 void free_task(struct task_struct
*tsk
)
115 prop_local_destroy_single(&tsk
->dirties
);
116 free_thread_info(tsk
->stack
);
117 rt_mutex_debug_task_free(tsk
);
118 free_task_struct(tsk
);
120 EXPORT_SYMBOL(free_task
);
122 void __put_task_struct(struct task_struct
*tsk
)
124 WARN_ON(!tsk
->exit_state
);
125 WARN_ON(atomic_read(&tsk
->usage
));
126 WARN_ON(tsk
== current
);
128 security_task_free(tsk
);
130 put_group_info(tsk
->group_info
);
131 delayacct_tsk_free(tsk
);
133 if (!profile_handoff_task(tsk
))
138 * macro override instead of weak attribute alias, to workaround
139 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
141 #ifndef arch_task_cache_init
142 #define arch_task_cache_init()
145 void __init
fork_init(unsigned long mempages
)
147 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
148 #ifndef ARCH_MIN_TASKALIGN
149 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
151 /* create a slab on which task_structs can be allocated */
153 kmem_cache_create("task_struct", sizeof(struct task_struct
),
154 ARCH_MIN_TASKALIGN
, SLAB_PANIC
, NULL
);
157 /* do the arch specific task caches init */
158 arch_task_cache_init();
161 * The default maximum number of threads is set to a safe
162 * value: the thread structures can take up at most half
165 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
168 * we need to allow at least 20 threads to boot a system
173 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
174 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
175 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
176 init_task
.signal
->rlim
[RLIMIT_NPROC
];
179 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
180 struct task_struct
*src
)
186 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
188 struct task_struct
*tsk
;
189 struct thread_info
*ti
;
190 unsigned long *stackend
;
194 prepare_to_copy(orig
);
196 tsk
= alloc_task_struct();
200 ti
= alloc_thread_info(tsk
);
202 free_task_struct(tsk
);
206 err
= arch_dup_task_struct(tsk
, orig
);
212 err
= prop_local_init_single(&tsk
->dirties
);
216 setup_thread_stack(tsk
, orig
);
217 stackend
= end_of_stack(tsk
);
218 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
220 #ifdef CONFIG_CC_STACKPROTECTOR
221 tsk
->stack_canary
= get_random_int();
224 /* One for us, one for whoever does the "release_task()" (usually parent) */
225 atomic_set(&tsk
->usage
,2);
226 atomic_set(&tsk
->fs_excl
, 0);
227 #ifdef CONFIG_BLK_DEV_IO_TRACE
230 tsk
->splice_pipe
= NULL
;
234 free_thread_info(ti
);
235 free_task_struct(tsk
);
240 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
242 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
243 struct rb_node
**rb_link
, *rb_parent
;
245 unsigned long charge
;
246 struct mempolicy
*pol
;
248 down_write(&oldmm
->mmap_sem
);
249 flush_cache_dup_mm(oldmm
);
251 * Not linked in yet - no deadlock potential:
253 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
257 mm
->mmap_cache
= NULL
;
258 mm
->free_area_cache
= oldmm
->mmap_base
;
259 mm
->cached_hole_size
= ~0UL;
261 cpus_clear(mm
->cpu_vm_mask
);
263 rb_link
= &mm
->mm_rb
.rb_node
;
267 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
270 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
271 long pages
= vma_pages(mpnt
);
272 mm
->total_vm
-= pages
;
273 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
278 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
279 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
280 if (security_vm_enough_memory(len
))
284 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
288 pol
= mpol_dup(vma_policy(mpnt
));
289 retval
= PTR_ERR(pol
);
291 goto fail_nomem_policy
;
292 vma_set_policy(tmp
, pol
);
293 tmp
->vm_flags
&= ~VM_LOCKED
;
299 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
301 if (tmp
->vm_flags
& VM_DENYWRITE
)
302 atomic_dec(&inode
->i_writecount
);
304 /* insert tmp into the share list, just after mpnt */
305 spin_lock(&file
->f_mapping
->i_mmap_lock
);
306 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
307 flush_dcache_mmap_lock(file
->f_mapping
);
308 vma_prio_tree_add(tmp
, mpnt
);
309 flush_dcache_mmap_unlock(file
->f_mapping
);
310 spin_unlock(&file
->f_mapping
->i_mmap_lock
);
314 * Link in the new vma and copy the page table entries.
317 pprev
= &tmp
->vm_next
;
319 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
320 rb_link
= &tmp
->vm_rb
.rb_right
;
321 rb_parent
= &tmp
->vm_rb
;
324 retval
= copy_page_range(mm
, oldmm
, mpnt
);
326 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
327 tmp
->vm_ops
->open(tmp
);
332 /* a new mm has just been created */
333 arch_dup_mmap(oldmm
, mm
);
336 up_write(&mm
->mmap_sem
);
338 up_write(&oldmm
->mmap_sem
);
341 kmem_cache_free(vm_area_cachep
, tmp
);
344 vm_unacct_memory(charge
);
348 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
350 mm
->pgd
= pgd_alloc(mm
);
351 if (unlikely(!mm
->pgd
))
356 static inline void mm_free_pgd(struct mm_struct
* mm
)
358 pgd_free(mm
, mm
->pgd
);
361 #define dup_mmap(mm, oldmm) (0)
362 #define mm_alloc_pgd(mm) (0)
363 #define mm_free_pgd(mm)
364 #endif /* CONFIG_MMU */
366 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
368 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
369 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
371 #include <linux/init_task.h>
373 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
375 atomic_set(&mm
->mm_users
, 1);
376 atomic_set(&mm
->mm_count
, 1);
377 init_rwsem(&mm
->mmap_sem
);
378 INIT_LIST_HEAD(&mm
->mmlist
);
379 mm
->flags
= (current
->mm
) ? current
->mm
->flags
380 : MMF_DUMP_FILTER_DEFAULT
;
381 mm
->core_waiters
= 0;
383 set_mm_counter(mm
, file_rss
, 0);
384 set_mm_counter(mm
, anon_rss
, 0);
385 spin_lock_init(&mm
->page_table_lock
);
386 rwlock_init(&mm
->ioctx_list_lock
);
387 mm
->ioctx_list
= NULL
;
388 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
389 mm
->cached_hole_size
= ~0UL;
390 mm_init_owner(mm
, p
);
392 if (likely(!mm_alloc_pgd(mm
))) {
402 * Allocate and initialize an mm_struct.
404 struct mm_struct
* mm_alloc(void)
406 struct mm_struct
* mm
;
410 memset(mm
, 0, sizeof(*mm
));
411 mm
= mm_init(mm
, current
);
417 * Called when the last reference to the mm
418 * is dropped: either by a lazy thread or by
419 * mmput. Free the page directory and the mm.
421 void __mmdrop(struct mm_struct
*mm
)
423 BUG_ON(mm
== &init_mm
);
428 EXPORT_SYMBOL_GPL(__mmdrop
);
431 * Decrement the use count and release all resources for an mm.
433 void mmput(struct mm_struct
*mm
)
437 if (atomic_dec_and_test(&mm
->mm_users
)) {
440 set_mm_exe_file(mm
, NULL
);
441 if (!list_empty(&mm
->mmlist
)) {
442 spin_lock(&mmlist_lock
);
443 list_del(&mm
->mmlist
);
444 spin_unlock(&mmlist_lock
);
450 EXPORT_SYMBOL_GPL(mmput
);
453 * get_task_mm - acquire a reference to the task's mm
455 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
456 * this kernel workthread has transiently adopted a user mm with use_mm,
457 * to do its AIO) is not set and if so returns a reference to it, after
458 * bumping up the use count. User must release the mm via mmput()
459 * after use. Typically used by /proc and ptrace.
461 struct mm_struct
*get_task_mm(struct task_struct
*task
)
463 struct mm_struct
*mm
;
468 if (task
->flags
& PF_BORROWED_MM
)
471 atomic_inc(&mm
->mm_users
);
476 EXPORT_SYMBOL_GPL(get_task_mm
);
478 /* Please note the differences between mmput and mm_release.
479 * mmput is called whenever we stop holding onto a mm_struct,
480 * error success whatever.
482 * mm_release is called after a mm_struct has been removed
483 * from the current process.
485 * This difference is important for error handling, when we
486 * only half set up a mm_struct for a new process and need to restore
487 * the old one. Because we mmput the new mm_struct before
488 * restoring the old one. . .
489 * Eric Biederman 10 January 1998
491 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
493 struct completion
*vfork_done
= tsk
->vfork_done
;
495 /* Get rid of any cached register state */
496 deactivate_mm(tsk
, mm
);
498 /* notify parent sleeping on vfork() */
500 tsk
->vfork_done
= NULL
;
501 complete(vfork_done
);
505 * If we're exiting normally, clear a user-space tid field if
506 * requested. We leave this alone when dying by signal, to leave
507 * the value intact in a core dump, and to save the unnecessary
508 * trouble otherwise. Userland only wants this done for a sys_exit.
510 if (tsk
->clear_child_tid
511 && !(tsk
->flags
& PF_SIGNALED
)
512 && atomic_read(&mm
->mm_users
) > 1) {
513 u32 __user
* tidptr
= tsk
->clear_child_tid
;
514 tsk
->clear_child_tid
= NULL
;
517 * We don't check the error code - if userspace has
518 * not set up a proper pointer then tough luck.
521 sys_futex(tidptr
, FUTEX_WAKE
, 1, NULL
, NULL
, 0);
526 * Allocate a new mm structure and copy contents from the
527 * mm structure of the passed in task structure.
529 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
531 struct mm_struct
*mm
, *oldmm
= current
->mm
;
541 memcpy(mm
, oldmm
, sizeof(*mm
));
543 /* Initializing for Swap token stuff */
544 mm
->token_priority
= 0;
545 mm
->last_interval
= 0;
547 if (!mm_init(mm
, tsk
))
550 if (init_new_context(tsk
, mm
))
553 dup_mm_exe_file(oldmm
, mm
);
555 err
= dup_mmap(mm
, oldmm
);
559 mm
->hiwater_rss
= get_mm_rss(mm
);
560 mm
->hiwater_vm
= mm
->total_vm
;
572 * If init_new_context() failed, we cannot use mmput() to free the mm
573 * because it calls destroy_context()
580 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
582 struct mm_struct
* mm
, *oldmm
;
585 tsk
->min_flt
= tsk
->maj_flt
= 0;
586 tsk
->nvcsw
= tsk
->nivcsw
= 0;
589 tsk
->active_mm
= NULL
;
592 * Are we cloning a kernel thread?
594 * We need to steal a active VM for that..
600 if (clone_flags
& CLONE_VM
) {
601 atomic_inc(&oldmm
->mm_users
);
612 /* Initializing for Swap token stuff */
613 mm
->token_priority
= 0;
614 mm
->last_interval
= 0;
624 static struct fs_struct
*__copy_fs_struct(struct fs_struct
*old
)
626 struct fs_struct
*fs
= kmem_cache_alloc(fs_cachep
, GFP_KERNEL
);
627 /* We don't need to lock fs - think why ;-) */
629 atomic_set(&fs
->count
, 1);
630 rwlock_init(&fs
->lock
);
631 fs
->umask
= old
->umask
;
632 read_lock(&old
->lock
);
633 fs
->root
= old
->root
;
634 path_get(&old
->root
);
637 if (old
->altroot
.dentry
) {
638 fs
->altroot
= old
->altroot
;
639 path_get(&old
->altroot
);
641 fs
->altroot
.mnt
= NULL
;
642 fs
->altroot
.dentry
= NULL
;
644 read_unlock(&old
->lock
);
649 struct fs_struct
*copy_fs_struct(struct fs_struct
*old
)
651 return __copy_fs_struct(old
);
654 EXPORT_SYMBOL_GPL(copy_fs_struct
);
656 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
658 if (clone_flags
& CLONE_FS
) {
659 atomic_inc(¤t
->fs
->count
);
662 tsk
->fs
= __copy_fs_struct(current
->fs
);
668 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
670 struct files_struct
*oldf
, *newf
;
674 * A background process may not have any files ...
676 oldf
= current
->files
;
680 if (clone_flags
& CLONE_FILES
) {
681 atomic_inc(&oldf
->count
);
685 newf
= dup_fd(oldf
, &error
);
695 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
698 struct io_context
*ioc
= current
->io_context
;
703 * Share io context with parent, if CLONE_IO is set
705 if (clone_flags
& CLONE_IO
) {
706 tsk
->io_context
= ioc_task_link(ioc
);
707 if (unlikely(!tsk
->io_context
))
709 } else if (ioprio_valid(ioc
->ioprio
)) {
710 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
711 if (unlikely(!tsk
->io_context
))
714 tsk
->io_context
->ioprio
= ioc
->ioprio
;
720 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
722 struct sighand_struct
*sig
;
724 if (clone_flags
& (CLONE_SIGHAND
| CLONE_THREAD
)) {
725 atomic_inc(¤t
->sighand
->count
);
728 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
729 rcu_assign_pointer(tsk
->sighand
, sig
);
732 atomic_set(&sig
->count
, 1);
733 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
737 void __cleanup_sighand(struct sighand_struct
*sighand
)
739 if (atomic_dec_and_test(&sighand
->count
))
740 kmem_cache_free(sighand_cachep
, sighand
);
743 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
745 struct signal_struct
*sig
;
748 if (clone_flags
& CLONE_THREAD
) {
749 atomic_inc(¤t
->signal
->count
);
750 atomic_inc(¤t
->signal
->live
);
753 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
758 ret
= copy_thread_group_keys(tsk
);
760 kmem_cache_free(signal_cachep
, sig
);
764 atomic_set(&sig
->count
, 1);
765 atomic_set(&sig
->live
, 1);
766 init_waitqueue_head(&sig
->wait_chldexit
);
768 sig
->group_exit_code
= 0;
769 sig
->group_exit_task
= NULL
;
770 sig
->group_stop_count
= 0;
771 sig
->curr_target
= tsk
;
772 init_sigpending(&sig
->shared_pending
);
773 INIT_LIST_HEAD(&sig
->posix_timers
);
775 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
776 sig
->it_real_incr
.tv64
= 0;
777 sig
->real_timer
.function
= it_real_fn
;
779 sig
->it_virt_expires
= cputime_zero
;
780 sig
->it_virt_incr
= cputime_zero
;
781 sig
->it_prof_expires
= cputime_zero
;
782 sig
->it_prof_incr
= cputime_zero
;
784 sig
->leader
= 0; /* session leadership doesn't inherit */
785 sig
->tty_old_pgrp
= NULL
;
787 sig
->utime
= sig
->stime
= sig
->cutime
= sig
->cstime
= cputime_zero
;
788 sig
->gtime
= cputime_zero
;
789 sig
->cgtime
= cputime_zero
;
790 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
791 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
792 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
793 sig
->sum_sched_runtime
= 0;
794 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
795 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
796 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
797 taskstats_tgid_init(sig
);
799 task_lock(current
->group_leader
);
800 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
801 task_unlock(current
->group_leader
);
803 if (sig
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
) {
805 * New sole thread in the process gets an expiry time
806 * of the whole CPU time limit.
808 tsk
->it_prof_expires
=
809 secs_to_cputime(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
811 acct_init_pacct(&sig
->pacct
);
818 void __cleanup_signal(struct signal_struct
*sig
)
820 exit_thread_group_keys(sig
);
821 kmem_cache_free(signal_cachep
, sig
);
824 static void cleanup_signal(struct task_struct
*tsk
)
826 struct signal_struct
*sig
= tsk
->signal
;
828 atomic_dec(&sig
->live
);
830 if (atomic_dec_and_test(&sig
->count
))
831 __cleanup_signal(sig
);
834 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
836 unsigned long new_flags
= p
->flags
;
838 new_flags
&= ~PF_SUPERPRIV
;
839 new_flags
|= PF_FORKNOEXEC
;
840 if (!(clone_flags
& CLONE_PTRACE
))
842 p
->flags
= new_flags
;
843 clear_freeze_flag(p
);
846 asmlinkage
long sys_set_tid_address(int __user
*tidptr
)
848 current
->clear_child_tid
= tidptr
;
850 return task_pid_vnr(current
);
853 static void rt_mutex_init_task(struct task_struct
*p
)
855 spin_lock_init(&p
->pi_lock
);
856 #ifdef CONFIG_RT_MUTEXES
857 plist_head_init(&p
->pi_waiters
, &p
->pi_lock
);
858 p
->pi_blocked_on
= NULL
;
862 #ifdef CONFIG_MM_OWNER
863 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
867 #endif /* CONFIG_MM_OWNER */
870 * This creates a new process as a copy of the old one,
871 * but does not actually start it yet.
873 * It copies the registers, and all the appropriate
874 * parts of the process environment (as per the clone
875 * flags). The actual kick-off is left to the caller.
877 static struct task_struct
*copy_process(unsigned long clone_flags
,
878 unsigned long stack_start
,
879 struct pt_regs
*regs
,
880 unsigned long stack_size
,
881 int __user
*child_tidptr
,
885 struct task_struct
*p
;
886 int cgroup_callbacks_done
= 0;
888 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
889 return ERR_PTR(-EINVAL
);
892 * Thread groups must share signals as well, and detached threads
893 * can only be started up within the thread group.
895 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
896 return ERR_PTR(-EINVAL
);
899 * Shared signal handlers imply shared VM. By way of the above,
900 * thread groups also imply shared VM. Blocking this case allows
901 * for various simplifications in other code.
903 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
904 return ERR_PTR(-EINVAL
);
906 retval
= security_task_create(clone_flags
);
911 p
= dup_task_struct(current
);
915 rt_mutex_init_task(p
);
917 #ifdef CONFIG_TRACE_IRQFLAGS
918 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
919 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
922 if (atomic_read(&p
->user
->processes
) >=
923 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
924 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
925 p
->user
!= current
->nsproxy
->user_ns
->root_user
)
929 atomic_inc(&p
->user
->__count
);
930 atomic_inc(&p
->user
->processes
);
931 get_group_info(p
->group_info
);
934 * If multiple threads are within copy_process(), then this check
935 * triggers too late. This doesn't hurt, the check is only there
936 * to stop root fork bombs.
938 if (nr_threads
>= max_threads
)
939 goto bad_fork_cleanup_count
;
941 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
942 goto bad_fork_cleanup_count
;
944 if (p
->binfmt
&& !try_module_get(p
->binfmt
->module
))
945 goto bad_fork_cleanup_put_domain
;
948 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
949 copy_flags(clone_flags
, p
);
950 INIT_LIST_HEAD(&p
->children
);
951 INIT_LIST_HEAD(&p
->sibling
);
952 #ifdef CONFIG_PREEMPT_RCU
953 p
->rcu_read_lock_nesting
= 0;
954 p
->rcu_flipctr_idx
= 0;
955 #endif /* #ifdef CONFIG_PREEMPT_RCU */
956 p
->vfork_done
= NULL
;
957 spin_lock_init(&p
->alloc_lock
);
959 clear_tsk_thread_flag(p
, TIF_SIGPENDING
);
960 init_sigpending(&p
->pending
);
962 p
->utime
= cputime_zero
;
963 p
->stime
= cputime_zero
;
964 p
->gtime
= cputime_zero
;
965 p
->utimescaled
= cputime_zero
;
966 p
->stimescaled
= cputime_zero
;
967 p
->prev_utime
= cputime_zero
;
968 p
->prev_stime
= cputime_zero
;
970 #ifdef CONFIG_DETECT_SOFTLOCKUP
971 p
->last_switch_count
= 0;
972 p
->last_switch_timestamp
= 0;
975 #ifdef CONFIG_TASK_XACCT
976 p
->rchar
= 0; /* I/O counter: bytes read */
977 p
->wchar
= 0; /* I/O counter: bytes written */
978 p
->syscr
= 0; /* I/O counter: read syscalls */
979 p
->syscw
= 0; /* I/O counter: write syscalls */
981 task_io_accounting_init(p
);
982 acct_clear_integrals(p
);
984 p
->it_virt_expires
= cputime_zero
;
985 p
->it_prof_expires
= cputime_zero
;
986 p
->it_sched_expires
= 0;
987 INIT_LIST_HEAD(&p
->cpu_timers
[0]);
988 INIT_LIST_HEAD(&p
->cpu_timers
[1]);
989 INIT_LIST_HEAD(&p
->cpu_timers
[2]);
991 p
->lock_depth
= -1; /* -1 = no lock */
992 do_posix_clock_monotonic_gettime(&p
->start_time
);
993 p
->real_start_time
= p
->start_time
;
994 monotonic_to_bootbased(&p
->real_start_time
);
995 #ifdef CONFIG_SECURITY
998 p
->cap_bset
= current
->cap_bset
;
999 p
->io_context
= NULL
;
1000 p
->audit_context
= NULL
;
1003 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1004 if (IS_ERR(p
->mempolicy
)) {
1005 retval
= PTR_ERR(p
->mempolicy
);
1006 p
->mempolicy
= NULL
;
1007 goto bad_fork_cleanup_cgroup
;
1009 mpol_fix_fork_child_flag(p
);
1011 #ifdef CONFIG_TRACE_IRQFLAGS
1013 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1014 p
->hardirqs_enabled
= 1;
1016 p
->hardirqs_enabled
= 0;
1018 p
->hardirq_enable_ip
= 0;
1019 p
->hardirq_enable_event
= 0;
1020 p
->hardirq_disable_ip
= _THIS_IP_
;
1021 p
->hardirq_disable_event
= 0;
1022 p
->softirqs_enabled
= 1;
1023 p
->softirq_enable_ip
= _THIS_IP_
;
1024 p
->softirq_enable_event
= 0;
1025 p
->softirq_disable_ip
= 0;
1026 p
->softirq_disable_event
= 0;
1027 p
->hardirq_context
= 0;
1028 p
->softirq_context
= 0;
1030 #ifdef CONFIG_LOCKDEP
1031 p
->lockdep_depth
= 0; /* no locks held yet */
1032 p
->curr_chain_key
= 0;
1033 p
->lockdep_recursion
= 0;
1036 #ifdef CONFIG_DEBUG_MUTEXES
1037 p
->blocked_on
= NULL
; /* not blocked yet */
1040 /* Perform scheduler related setup. Assign this task to a CPU. */
1041 sched_fork(p
, clone_flags
);
1043 if ((retval
= security_task_alloc(p
)))
1044 goto bad_fork_cleanup_policy
;
1045 if ((retval
= audit_alloc(p
)))
1046 goto bad_fork_cleanup_security
;
1047 /* copy all the process information */
1048 if ((retval
= copy_semundo(clone_flags
, p
)))
1049 goto bad_fork_cleanup_audit
;
1050 if ((retval
= copy_files(clone_flags
, p
)))
1051 goto bad_fork_cleanup_semundo
;
1052 if ((retval
= copy_fs(clone_flags
, p
)))
1053 goto bad_fork_cleanup_files
;
1054 if ((retval
= copy_sighand(clone_flags
, p
)))
1055 goto bad_fork_cleanup_fs
;
1056 if ((retval
= copy_signal(clone_flags
, p
)))
1057 goto bad_fork_cleanup_sighand
;
1058 if ((retval
= copy_mm(clone_flags
, p
)))
1059 goto bad_fork_cleanup_signal
;
1060 if ((retval
= copy_keys(clone_flags
, p
)))
1061 goto bad_fork_cleanup_mm
;
1062 if ((retval
= copy_namespaces(clone_flags
, p
)))
1063 goto bad_fork_cleanup_keys
;
1064 if ((retval
= copy_io(clone_flags
, p
)))
1065 goto bad_fork_cleanup_namespaces
;
1066 retval
= copy_thread(0, clone_flags
, stack_start
, stack_size
, p
, regs
);
1068 goto bad_fork_cleanup_io
;
1070 if (pid
!= &init_struct_pid
) {
1072 pid
= alloc_pid(task_active_pid_ns(p
));
1074 goto bad_fork_cleanup_io
;
1076 if (clone_flags
& CLONE_NEWPID
) {
1077 retval
= pid_ns_prepare_proc(task_active_pid_ns(p
));
1079 goto bad_fork_free_pid
;
1083 p
->pid
= pid_nr(pid
);
1085 if (clone_flags
& CLONE_THREAD
)
1086 p
->tgid
= current
->tgid
;
1088 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1090 * Clear TID on mm_release()?
1092 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1094 p
->robust_list
= NULL
;
1095 #ifdef CONFIG_COMPAT
1096 p
->compat_robust_list
= NULL
;
1098 INIT_LIST_HEAD(&p
->pi_state_list
);
1099 p
->pi_state_cache
= NULL
;
1102 * sigaltstack should be cleared when sharing the same VM
1104 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1105 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1108 * Syscall tracing should be turned off in the child regardless
1111 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1112 #ifdef TIF_SYSCALL_EMU
1113 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1115 clear_all_latency_tracing(p
);
1117 /* Our parent execution domain becomes current domain
1118 These must match for thread signalling to apply */
1119 p
->parent_exec_id
= p
->self_exec_id
;
1121 /* ok, now we should be set up.. */
1122 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1123 p
->pdeath_signal
= 0;
1127 * Ok, make it visible to the rest of the system.
1128 * We dont wake it up yet.
1130 p
->group_leader
= p
;
1131 INIT_LIST_HEAD(&p
->thread_group
);
1132 INIT_LIST_HEAD(&p
->ptrace_children
);
1133 INIT_LIST_HEAD(&p
->ptrace_list
);
1135 /* Now that the task is set up, run cgroup callbacks if
1136 * necessary. We need to run them before the task is visible
1137 * on the tasklist. */
1138 cgroup_fork_callbacks(p
);
1139 cgroup_callbacks_done
= 1;
1141 /* Need tasklist lock for parent etc handling! */
1142 write_lock_irq(&tasklist_lock
);
1145 * The task hasn't been attached yet, so its cpus_allowed mask will
1146 * not be changed, nor will its assigned CPU.
1148 * The cpus_allowed mask of the parent may have changed after it was
1149 * copied first time - so re-copy it here, then check the child's CPU
1150 * to ensure it is on a valid CPU (and if not, just force it back to
1151 * parent's CPU). This avoids alot of nasty races.
1153 p
->cpus_allowed
= current
->cpus_allowed
;
1154 p
->rt
.nr_cpus_allowed
= current
->rt
.nr_cpus_allowed
;
1155 if (unlikely(!cpu_isset(task_cpu(p
), p
->cpus_allowed
) ||
1156 !cpu_online(task_cpu(p
))))
1157 set_task_cpu(p
, smp_processor_id());
1159 /* CLONE_PARENT re-uses the old parent */
1160 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
))
1161 p
->real_parent
= current
->real_parent
;
1163 p
->real_parent
= current
;
1164 p
->parent
= p
->real_parent
;
1166 spin_lock(¤t
->sighand
->siglock
);
1169 * Process group and session signals need to be delivered to just the
1170 * parent before the fork or both the parent and the child after the
1171 * fork. Restart if a signal comes in before we add the new process to
1172 * it's process group.
1173 * A fatal signal pending means that current will exit, so the new
1174 * thread can't slip out of an OOM kill (or normal SIGKILL).
1176 recalc_sigpending();
1177 if (signal_pending(current
)) {
1178 spin_unlock(¤t
->sighand
->siglock
);
1179 write_unlock_irq(&tasklist_lock
);
1180 retval
= -ERESTARTNOINTR
;
1181 goto bad_fork_free_pid
;
1184 if (clone_flags
& CLONE_THREAD
) {
1185 p
->group_leader
= current
->group_leader
;
1186 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1188 if (!cputime_eq(current
->signal
->it_virt_expires
,
1190 !cputime_eq(current
->signal
->it_prof_expires
,
1192 current
->signal
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
||
1193 !list_empty(¤t
->signal
->cpu_timers
[0]) ||
1194 !list_empty(¤t
->signal
->cpu_timers
[1]) ||
1195 !list_empty(¤t
->signal
->cpu_timers
[2])) {
1197 * Have child wake up on its first tick to check
1198 * for process CPU timers.
1200 p
->it_prof_expires
= jiffies_to_cputime(1);
1204 if (likely(p
->pid
)) {
1206 if (unlikely(p
->ptrace
& PT_PTRACED
))
1207 __ptrace_link(p
, current
->parent
);
1209 if (thread_group_leader(p
)) {
1210 if (clone_flags
& CLONE_NEWPID
)
1211 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1213 p
->signal
->leader_pid
= pid
;
1214 p
->signal
->tty
= current
->signal
->tty
;
1215 set_task_pgrp(p
, task_pgrp_nr(current
));
1216 set_task_session(p
, task_session_nr(current
));
1217 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1218 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1219 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1220 __get_cpu_var(process_counts
)++;
1222 attach_pid(p
, PIDTYPE_PID
, pid
);
1227 spin_unlock(¤t
->sighand
->siglock
);
1228 write_unlock_irq(&tasklist_lock
);
1229 proc_fork_connector(p
);
1230 cgroup_post_fork(p
);
1234 if (pid
!= &init_struct_pid
)
1236 bad_fork_cleanup_io
:
1237 put_io_context(p
->io_context
);
1238 bad_fork_cleanup_namespaces
:
1239 exit_task_namespaces(p
);
1240 bad_fork_cleanup_keys
:
1242 bad_fork_cleanup_mm
:
1245 bad_fork_cleanup_signal
:
1247 bad_fork_cleanup_sighand
:
1248 __cleanup_sighand(p
->sighand
);
1249 bad_fork_cleanup_fs
:
1250 exit_fs(p
); /* blocking */
1251 bad_fork_cleanup_files
:
1252 exit_files(p
); /* blocking */
1253 bad_fork_cleanup_semundo
:
1255 bad_fork_cleanup_audit
:
1257 bad_fork_cleanup_security
:
1258 security_task_free(p
);
1259 bad_fork_cleanup_policy
:
1261 mpol_put(p
->mempolicy
);
1262 bad_fork_cleanup_cgroup
:
1264 cgroup_exit(p
, cgroup_callbacks_done
);
1265 delayacct_tsk_free(p
);
1267 module_put(p
->binfmt
->module
);
1268 bad_fork_cleanup_put_domain
:
1269 module_put(task_thread_info(p
)->exec_domain
->module
);
1270 bad_fork_cleanup_count
:
1271 put_group_info(p
->group_info
);
1272 atomic_dec(&p
->user
->processes
);
1277 return ERR_PTR(retval
);
1280 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1282 memset(regs
, 0, sizeof(struct pt_regs
));
1286 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1288 struct task_struct
*task
;
1289 struct pt_regs regs
;
1291 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1294 init_idle(task
, cpu
);
1299 static int fork_traceflag(unsigned clone_flags
)
1301 if (clone_flags
& CLONE_UNTRACED
)
1303 else if (clone_flags
& CLONE_VFORK
) {
1304 if (current
->ptrace
& PT_TRACE_VFORK
)
1305 return PTRACE_EVENT_VFORK
;
1306 } else if ((clone_flags
& CSIGNAL
) != SIGCHLD
) {
1307 if (current
->ptrace
& PT_TRACE_CLONE
)
1308 return PTRACE_EVENT_CLONE
;
1309 } else if (current
->ptrace
& PT_TRACE_FORK
)
1310 return PTRACE_EVENT_FORK
;
1316 * Ok, this is the main fork-routine.
1318 * It copies the process, and if successful kick-starts
1319 * it and waits for it to finish using the VM if required.
1321 long do_fork(unsigned long clone_flags
,
1322 unsigned long stack_start
,
1323 struct pt_regs
*regs
,
1324 unsigned long stack_size
,
1325 int __user
*parent_tidptr
,
1326 int __user
*child_tidptr
)
1328 struct task_struct
*p
;
1333 * We hope to recycle these flags after 2.6.26
1335 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1336 static int __read_mostly count
= 100;
1338 if (count
> 0 && printk_ratelimit()) {
1339 char comm
[TASK_COMM_LEN
];
1342 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1343 "clone flags 0x%lx\n",
1344 get_task_comm(comm
, current
),
1345 clone_flags
& CLONE_STOPPED
);
1349 if (unlikely(current
->ptrace
)) {
1350 trace
= fork_traceflag (clone_flags
);
1352 clone_flags
|= CLONE_PTRACE
;
1355 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1356 child_tidptr
, NULL
);
1358 * Do this prior waking up the new thread - the thread pointer
1359 * might get invalid after that point, if the thread exits quickly.
1362 struct completion vfork
;
1364 nr
= task_pid_vnr(p
);
1366 if (clone_flags
& CLONE_PARENT_SETTID
)
1367 put_user(nr
, parent_tidptr
);
1369 if (clone_flags
& CLONE_VFORK
) {
1370 p
->vfork_done
= &vfork
;
1371 init_completion(&vfork
);
1374 if ((p
->ptrace
& PT_PTRACED
) || (clone_flags
& CLONE_STOPPED
)) {
1376 * We'll start up with an immediate SIGSTOP.
1378 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1379 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1382 if (!(clone_flags
& CLONE_STOPPED
))
1383 wake_up_new_task(p
, clone_flags
);
1385 __set_task_state(p
, TASK_STOPPED
);
1387 if (unlikely (trace
)) {
1388 current
->ptrace_message
= nr
;
1389 ptrace_notify ((trace
<< 8) | SIGTRAP
);
1392 if (clone_flags
& CLONE_VFORK
) {
1393 freezer_do_not_count();
1394 wait_for_completion(&vfork
);
1396 if (unlikely (current
->ptrace
& PT_TRACE_VFORK_DONE
)) {
1397 current
->ptrace_message
= nr
;
1398 ptrace_notify ((PTRACE_EVENT_VFORK_DONE
<< 8) | SIGTRAP
);
1407 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1408 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1411 static void sighand_ctor(struct kmem_cache
*cachep
, void *data
)
1413 struct sighand_struct
*sighand
= data
;
1415 spin_lock_init(&sighand
->siglock
);
1416 init_waitqueue_head(&sighand
->signalfd_wqh
);
1419 void __init
proc_caches_init(void)
1421 sighand_cachep
= kmem_cache_create("sighand_cache",
1422 sizeof(struct sighand_struct
), 0,
1423 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
,
1425 signal_cachep
= kmem_cache_create("signal_cache",
1426 sizeof(struct signal_struct
), 0,
1427 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1428 files_cachep
= kmem_cache_create("files_cache",
1429 sizeof(struct files_struct
), 0,
1430 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1431 fs_cachep
= kmem_cache_create("fs_cache",
1432 sizeof(struct fs_struct
), 0,
1433 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1434 vm_area_cachep
= kmem_cache_create("vm_area_struct",
1435 sizeof(struct vm_area_struct
), 0,
1437 mm_cachep
= kmem_cache_create("mm_struct",
1438 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1439 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1443 * Check constraints on flags passed to the unshare system call and
1444 * force unsharing of additional process context as appropriate.
1446 static void check_unshare_flags(unsigned long *flags_ptr
)
1449 * If unsharing a thread from a thread group, must also
1452 if (*flags_ptr
& CLONE_THREAD
)
1453 *flags_ptr
|= CLONE_VM
;
1456 * If unsharing vm, must also unshare signal handlers.
1458 if (*flags_ptr
& CLONE_VM
)
1459 *flags_ptr
|= CLONE_SIGHAND
;
1462 * If unsharing signal handlers and the task was created
1463 * using CLONE_THREAD, then must unshare the thread
1465 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1466 (atomic_read(¤t
->signal
->count
) > 1))
1467 *flags_ptr
|= CLONE_THREAD
;
1470 * If unsharing namespace, must also unshare filesystem information.
1472 if (*flags_ptr
& CLONE_NEWNS
)
1473 *flags_ptr
|= CLONE_FS
;
1477 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1479 static int unshare_thread(unsigned long unshare_flags
)
1481 if (unshare_flags
& CLONE_THREAD
)
1488 * Unshare the filesystem structure if it is being shared
1490 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1492 struct fs_struct
*fs
= current
->fs
;
1494 if ((unshare_flags
& CLONE_FS
) &&
1495 (fs
&& atomic_read(&fs
->count
) > 1)) {
1496 *new_fsp
= __copy_fs_struct(current
->fs
);
1505 * Unsharing of sighand is not supported yet
1507 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1509 struct sighand_struct
*sigh
= current
->sighand
;
1511 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1518 * Unshare vm if it is being shared
1520 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1522 struct mm_struct
*mm
= current
->mm
;
1524 if ((unshare_flags
& CLONE_VM
) &&
1525 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1533 * Unshare file descriptor table if it is being shared
1535 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1537 struct files_struct
*fd
= current
->files
;
1540 if ((unshare_flags
& CLONE_FILES
) &&
1541 (fd
&& atomic_read(&fd
->count
) > 1)) {
1542 *new_fdp
= dup_fd(fd
, &error
);
1551 * unshare allows a process to 'unshare' part of the process
1552 * context which was originally shared using clone. copy_*
1553 * functions used by do_fork() cannot be used here directly
1554 * because they modify an inactive task_struct that is being
1555 * constructed. Here we are modifying the current, active,
1558 asmlinkage
long sys_unshare(unsigned long unshare_flags
)
1561 struct fs_struct
*fs
, *new_fs
= NULL
;
1562 struct sighand_struct
*new_sigh
= NULL
;
1563 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1564 struct files_struct
*fd
, *new_fd
= NULL
;
1565 struct nsproxy
*new_nsproxy
= NULL
;
1568 check_unshare_flags(&unshare_flags
);
1570 /* Return -EINVAL for all unsupported flags */
1572 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1573 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1574 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWUSER
|
1576 goto bad_unshare_out
;
1579 * CLONE_NEWIPC must also detach from the undolist: after switching
1580 * to a new ipc namespace, the semaphore arrays from the old
1581 * namespace are unreachable.
1583 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1585 if ((err
= unshare_thread(unshare_flags
)))
1586 goto bad_unshare_out
;
1587 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1588 goto bad_unshare_cleanup_thread
;
1589 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1590 goto bad_unshare_cleanup_fs
;
1591 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1592 goto bad_unshare_cleanup_sigh
;
1593 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1594 goto bad_unshare_cleanup_vm
;
1595 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1597 goto bad_unshare_cleanup_fd
;
1599 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1602 * CLONE_SYSVSEM is equivalent to sys_exit().
1608 switch_task_namespaces(current
, new_nsproxy
);
1616 current
->fs
= new_fs
;
1622 active_mm
= current
->active_mm
;
1623 current
->mm
= new_mm
;
1624 current
->active_mm
= new_mm
;
1625 activate_mm(active_mm
, new_mm
);
1630 fd
= current
->files
;
1631 current
->files
= new_fd
;
1635 task_unlock(current
);
1639 put_nsproxy(new_nsproxy
);
1641 bad_unshare_cleanup_fd
:
1643 put_files_struct(new_fd
);
1645 bad_unshare_cleanup_vm
:
1649 bad_unshare_cleanup_sigh
:
1651 if (atomic_dec_and_test(&new_sigh
->count
))
1652 kmem_cache_free(sighand_cachep
, new_sigh
);
1654 bad_unshare_cleanup_fs
:
1656 put_fs_struct(new_fs
);
1658 bad_unshare_cleanup_thread
:
1664 * Helper to unshare the files of the current task.
1665 * We don't want to expose copy_files internals to
1666 * the exec layer of the kernel.
1669 int unshare_files(struct files_struct
**displaced
)
1671 struct task_struct
*task
= current
;
1672 struct files_struct
*copy
= NULL
;
1675 error
= unshare_fd(CLONE_FILES
, ©
);
1676 if (error
|| !copy
) {
1680 *displaced
= task
->files
;