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/iocontext.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.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/task_io_accounting_ops.h>
43 #include <linux/rcupdate.h>
44 #include <linux/ptrace.h>
45 #include <linux/mount.h>
46 #include <linux/audit.h>
47 #include <linux/memcontrol.h>
48 #include <linux/profile.h>
49 #include <linux/rmap.h>
50 #include <linux/acct.h>
51 #include <linux/tsacct_kern.h>
52 #include <linux/cn_proc.h>
53 #include <linux/freezer.h>
54 #include <linux/delayacct.h>
55 #include <linux/taskstats_kern.h>
56 #include <linux/random.h>
57 #include <linux/tty.h>
58 #include <linux/proc_fs.h>
59 #include <linux/blkdev.h>
61 #include <asm/pgtable.h>
62 #include <asm/pgalloc.h>
63 #include <asm/uaccess.h>
64 #include <asm/mmu_context.h>
65 #include <asm/cacheflush.h>
66 #include <asm/tlbflush.h>
69 * Protected counters by write_lock_irq(&tasklist_lock)
71 unsigned long total_forks
; /* Handle normal Linux uptimes. */
72 int nr_threads
; /* The idle threads do not count.. */
74 int max_threads
; /* tunable limit on nr_threads */
76 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
78 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
80 int nr_processes(void)
85 for_each_online_cpu(cpu
)
86 total
+= per_cpu(process_counts
, cpu
);
91 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
92 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
93 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
94 static struct kmem_cache
*task_struct_cachep
;
97 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
98 static inline struct thread_info
*alloc_thread_info(struct task_struct
*tsk
)
100 #ifdef CONFIG_DEBUG_STACK_USAGE
101 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
103 gfp_t mask
= GFP_KERNEL
;
105 return (struct thread_info
*)__get_free_pages(mask
, THREAD_SIZE_ORDER
);
108 static inline void free_thread_info(struct thread_info
*ti
)
110 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
114 /* SLAB cache for signal_struct structures (tsk->signal) */
115 static struct kmem_cache
*signal_cachep
;
117 /* SLAB cache for sighand_struct structures (tsk->sighand) */
118 struct kmem_cache
*sighand_cachep
;
120 /* SLAB cache for files_struct structures (tsk->files) */
121 struct kmem_cache
*files_cachep
;
123 /* SLAB cache for fs_struct structures (tsk->fs) */
124 struct kmem_cache
*fs_cachep
;
126 /* SLAB cache for vm_area_struct structures */
127 struct kmem_cache
*vm_area_cachep
;
129 /* SLAB cache for mm_struct structures (tsk->mm) */
130 static struct kmem_cache
*mm_cachep
;
132 void free_task(struct task_struct
*tsk
)
134 prop_local_destroy_single(&tsk
->dirties
);
135 free_thread_info(tsk
->stack
);
136 rt_mutex_debug_task_free(tsk
);
137 free_task_struct(tsk
);
139 EXPORT_SYMBOL(free_task
);
141 void __put_task_struct(struct task_struct
*tsk
)
143 WARN_ON(!tsk
->exit_state
);
144 WARN_ON(atomic_read(&tsk
->usage
));
145 WARN_ON(tsk
== current
);
147 security_task_free(tsk
);
149 put_group_info(tsk
->group_info
);
150 delayacct_tsk_free(tsk
);
152 if (!profile_handoff_task(tsk
))
157 * macro override instead of weak attribute alias, to workaround
158 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
160 #ifndef arch_task_cache_init
161 #define arch_task_cache_init()
164 void __init
fork_init(unsigned long mempages
)
166 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
167 #ifndef ARCH_MIN_TASKALIGN
168 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
170 /* create a slab on which task_structs can be allocated */
172 kmem_cache_create("task_struct", sizeof(struct task_struct
),
173 ARCH_MIN_TASKALIGN
, SLAB_PANIC
, NULL
);
176 /* do the arch specific task caches init */
177 arch_task_cache_init();
180 * The default maximum number of threads is set to a safe
181 * value: the thread structures can take up at most half
184 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
187 * we need to allow at least 20 threads to boot a system
192 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
193 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
194 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
195 init_task
.signal
->rlim
[RLIMIT_NPROC
];
198 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
199 struct task_struct
*src
)
205 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
207 struct task_struct
*tsk
;
208 struct thread_info
*ti
;
211 prepare_to_copy(orig
);
213 tsk
= alloc_task_struct();
217 ti
= alloc_thread_info(tsk
);
219 free_task_struct(tsk
);
223 err
= arch_dup_task_struct(tsk
, orig
);
229 err
= prop_local_init_single(&tsk
->dirties
);
233 setup_thread_stack(tsk
, orig
);
235 #ifdef CONFIG_CC_STACKPROTECTOR
236 tsk
->stack_canary
= get_random_int();
239 /* One for us, one for whoever does the "release_task()" (usually parent) */
240 atomic_set(&tsk
->usage
,2);
241 atomic_set(&tsk
->fs_excl
, 0);
242 #ifdef CONFIG_BLK_DEV_IO_TRACE
245 tsk
->splice_pipe
= NULL
;
249 free_thread_info(ti
);
250 free_task_struct(tsk
);
255 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
257 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
258 struct rb_node
**rb_link
, *rb_parent
;
260 unsigned long charge
;
261 struct mempolicy
*pol
;
263 down_write(&oldmm
->mmap_sem
);
264 flush_cache_dup_mm(oldmm
);
266 * Not linked in yet - no deadlock potential:
268 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
272 mm
->mmap_cache
= NULL
;
273 mm
->free_area_cache
= oldmm
->mmap_base
;
274 mm
->cached_hole_size
= ~0UL;
276 cpus_clear(mm
->cpu_vm_mask
);
278 rb_link
= &mm
->mm_rb
.rb_node
;
282 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
285 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
286 long pages
= vma_pages(mpnt
);
287 mm
->total_vm
-= pages
;
288 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
293 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
294 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
295 if (security_vm_enough_memory(len
))
299 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
303 pol
= mpol_dup(vma_policy(mpnt
));
304 retval
= PTR_ERR(pol
);
306 goto fail_nomem_policy
;
307 vma_set_policy(tmp
, pol
);
308 tmp
->vm_flags
&= ~VM_LOCKED
;
314 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
316 if (tmp
->vm_flags
& VM_DENYWRITE
)
317 atomic_dec(&inode
->i_writecount
);
319 /* insert tmp into the share list, just after mpnt */
320 spin_lock(&file
->f_mapping
->i_mmap_lock
);
321 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
322 flush_dcache_mmap_lock(file
->f_mapping
);
323 vma_prio_tree_add(tmp
, mpnt
);
324 flush_dcache_mmap_unlock(file
->f_mapping
);
325 spin_unlock(&file
->f_mapping
->i_mmap_lock
);
329 * Clear hugetlb-related page reserves for children. This only
330 * affects MAP_PRIVATE mappings. Faults generated by the child
331 * are not guaranteed to succeed, even if read-only
333 if (is_vm_hugetlb_page(tmp
))
334 reset_vma_resv_huge_pages(tmp
);
337 * Link in the new vma and copy the page table entries.
340 pprev
= &tmp
->vm_next
;
342 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
343 rb_link
= &tmp
->vm_rb
.rb_right
;
344 rb_parent
= &tmp
->vm_rb
;
347 retval
= copy_page_range(mm
, oldmm
, mpnt
);
349 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
350 tmp
->vm_ops
->open(tmp
);
355 /* a new mm has just been created */
356 arch_dup_mmap(oldmm
, mm
);
359 up_write(&mm
->mmap_sem
);
361 up_write(&oldmm
->mmap_sem
);
364 kmem_cache_free(vm_area_cachep
, tmp
);
367 vm_unacct_memory(charge
);
371 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
373 mm
->pgd
= pgd_alloc(mm
);
374 if (unlikely(!mm
->pgd
))
379 static inline void mm_free_pgd(struct mm_struct
* mm
)
381 pgd_free(mm
, mm
->pgd
);
384 #define dup_mmap(mm, oldmm) (0)
385 #define mm_alloc_pgd(mm) (0)
386 #define mm_free_pgd(mm)
387 #endif /* CONFIG_MMU */
389 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
391 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
392 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
394 #include <linux/init_task.h>
396 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
398 atomic_set(&mm
->mm_users
, 1);
399 atomic_set(&mm
->mm_count
, 1);
400 init_rwsem(&mm
->mmap_sem
);
401 INIT_LIST_HEAD(&mm
->mmlist
);
402 mm
->flags
= (current
->mm
) ? current
->mm
->flags
403 : MMF_DUMP_FILTER_DEFAULT
;
404 mm
->core_state
= NULL
;
406 set_mm_counter(mm
, file_rss
, 0);
407 set_mm_counter(mm
, anon_rss
, 0);
408 spin_lock_init(&mm
->page_table_lock
);
409 rwlock_init(&mm
->ioctx_list_lock
);
410 mm
->ioctx_list
= NULL
;
411 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
412 mm
->cached_hole_size
= ~0UL;
413 mm_init_owner(mm
, p
);
415 if (likely(!mm_alloc_pgd(mm
))) {
425 * Allocate and initialize an mm_struct.
427 struct mm_struct
* mm_alloc(void)
429 struct mm_struct
* mm
;
433 memset(mm
, 0, sizeof(*mm
));
434 mm
= mm_init(mm
, current
);
440 * Called when the last reference to the mm
441 * is dropped: either by a lazy thread or by
442 * mmput. Free the page directory and the mm.
444 void __mmdrop(struct mm_struct
*mm
)
446 BUG_ON(mm
== &init_mm
);
451 EXPORT_SYMBOL_GPL(__mmdrop
);
454 * Decrement the use count and release all resources for an mm.
456 void mmput(struct mm_struct
*mm
)
460 if (atomic_dec_and_test(&mm
->mm_users
)) {
463 set_mm_exe_file(mm
, NULL
);
464 if (!list_empty(&mm
->mmlist
)) {
465 spin_lock(&mmlist_lock
);
466 list_del(&mm
->mmlist
);
467 spin_unlock(&mmlist_lock
);
473 EXPORT_SYMBOL_GPL(mmput
);
476 * get_task_mm - acquire a reference to the task's mm
478 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
479 * this kernel workthread has transiently adopted a user mm with use_mm,
480 * to do its AIO) is not set and if so returns a reference to it, after
481 * bumping up the use count. User must release the mm via mmput()
482 * after use. Typically used by /proc and ptrace.
484 struct mm_struct
*get_task_mm(struct task_struct
*task
)
486 struct mm_struct
*mm
;
491 if (task
->flags
& PF_KTHREAD
)
494 atomic_inc(&mm
->mm_users
);
499 EXPORT_SYMBOL_GPL(get_task_mm
);
501 /* Please note the differences between mmput and mm_release.
502 * mmput is called whenever we stop holding onto a mm_struct,
503 * error success whatever.
505 * mm_release is called after a mm_struct has been removed
506 * from the current process.
508 * This difference is important for error handling, when we
509 * only half set up a mm_struct for a new process and need to restore
510 * the old one. Because we mmput the new mm_struct before
511 * restoring the old one. . .
512 * Eric Biederman 10 January 1998
514 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
516 struct completion
*vfork_done
= tsk
->vfork_done
;
518 /* Get rid of any cached register state */
519 deactivate_mm(tsk
, mm
);
521 /* notify parent sleeping on vfork() */
523 tsk
->vfork_done
= NULL
;
524 complete(vfork_done
);
528 * If we're exiting normally, clear a user-space tid field if
529 * requested. We leave this alone when dying by signal, to leave
530 * the value intact in a core dump, and to save the unnecessary
531 * trouble otherwise. Userland only wants this done for a sys_exit.
533 if (tsk
->clear_child_tid
534 && !(tsk
->flags
& PF_SIGNALED
)
535 && atomic_read(&mm
->mm_users
) > 1) {
536 u32 __user
* tidptr
= tsk
->clear_child_tid
;
537 tsk
->clear_child_tid
= NULL
;
540 * We don't check the error code - if userspace has
541 * not set up a proper pointer then tough luck.
544 sys_futex(tidptr
, FUTEX_WAKE
, 1, NULL
, NULL
, 0);
549 * Allocate a new mm structure and copy contents from the
550 * mm structure of the passed in task structure.
552 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
554 struct mm_struct
*mm
, *oldmm
= current
->mm
;
564 memcpy(mm
, oldmm
, sizeof(*mm
));
566 /* Initializing for Swap token stuff */
567 mm
->token_priority
= 0;
568 mm
->last_interval
= 0;
570 if (!mm_init(mm
, tsk
))
573 if (init_new_context(tsk
, mm
))
576 dup_mm_exe_file(oldmm
, mm
);
578 err
= dup_mmap(mm
, oldmm
);
582 mm
->hiwater_rss
= get_mm_rss(mm
);
583 mm
->hiwater_vm
= mm
->total_vm
;
595 * If init_new_context() failed, we cannot use mmput() to free the mm
596 * because it calls destroy_context()
603 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
605 struct mm_struct
* mm
, *oldmm
;
608 tsk
->min_flt
= tsk
->maj_flt
= 0;
609 tsk
->nvcsw
= tsk
->nivcsw
= 0;
612 tsk
->active_mm
= NULL
;
615 * Are we cloning a kernel thread?
617 * We need to steal a active VM for that..
623 if (clone_flags
& CLONE_VM
) {
624 atomic_inc(&oldmm
->mm_users
);
635 /* Initializing for Swap token stuff */
636 mm
->token_priority
= 0;
637 mm
->last_interval
= 0;
647 static struct fs_struct
*__copy_fs_struct(struct fs_struct
*old
)
649 struct fs_struct
*fs
= kmem_cache_alloc(fs_cachep
, GFP_KERNEL
);
650 /* We don't need to lock fs - think why ;-) */
652 atomic_set(&fs
->count
, 1);
653 rwlock_init(&fs
->lock
);
654 fs
->umask
= old
->umask
;
655 read_lock(&old
->lock
);
656 fs
->root
= old
->root
;
657 path_get(&old
->root
);
660 read_unlock(&old
->lock
);
665 struct fs_struct
*copy_fs_struct(struct fs_struct
*old
)
667 return __copy_fs_struct(old
);
670 EXPORT_SYMBOL_GPL(copy_fs_struct
);
672 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
674 if (clone_flags
& CLONE_FS
) {
675 atomic_inc(¤t
->fs
->count
);
678 tsk
->fs
= __copy_fs_struct(current
->fs
);
684 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
686 struct files_struct
*oldf
, *newf
;
690 * A background process may not have any files ...
692 oldf
= current
->files
;
696 if (clone_flags
& CLONE_FILES
) {
697 atomic_inc(&oldf
->count
);
701 newf
= dup_fd(oldf
, &error
);
711 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
714 struct io_context
*ioc
= current
->io_context
;
719 * Share io context with parent, if CLONE_IO is set
721 if (clone_flags
& CLONE_IO
) {
722 tsk
->io_context
= ioc_task_link(ioc
);
723 if (unlikely(!tsk
->io_context
))
725 } else if (ioprio_valid(ioc
->ioprio
)) {
726 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
727 if (unlikely(!tsk
->io_context
))
730 tsk
->io_context
->ioprio
= ioc
->ioprio
;
736 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
738 struct sighand_struct
*sig
;
740 if (clone_flags
& (CLONE_SIGHAND
| CLONE_THREAD
)) {
741 atomic_inc(¤t
->sighand
->count
);
744 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
745 rcu_assign_pointer(tsk
->sighand
, sig
);
748 atomic_set(&sig
->count
, 1);
749 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
753 void __cleanup_sighand(struct sighand_struct
*sighand
)
755 if (atomic_dec_and_test(&sighand
->count
))
756 kmem_cache_free(sighand_cachep
, sighand
);
759 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
761 struct signal_struct
*sig
;
764 if (clone_flags
& CLONE_THREAD
) {
765 atomic_inc(¤t
->signal
->count
);
766 atomic_inc(¤t
->signal
->live
);
769 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
774 ret
= copy_thread_group_keys(tsk
);
776 kmem_cache_free(signal_cachep
, sig
);
780 atomic_set(&sig
->count
, 1);
781 atomic_set(&sig
->live
, 1);
782 init_waitqueue_head(&sig
->wait_chldexit
);
784 sig
->group_exit_code
= 0;
785 sig
->group_exit_task
= NULL
;
786 sig
->group_stop_count
= 0;
787 sig
->curr_target
= tsk
;
788 init_sigpending(&sig
->shared_pending
);
789 INIT_LIST_HEAD(&sig
->posix_timers
);
791 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
792 sig
->it_real_incr
.tv64
= 0;
793 sig
->real_timer
.function
= it_real_fn
;
795 sig
->it_virt_expires
= cputime_zero
;
796 sig
->it_virt_incr
= cputime_zero
;
797 sig
->it_prof_expires
= cputime_zero
;
798 sig
->it_prof_incr
= cputime_zero
;
800 sig
->leader
= 0; /* session leadership doesn't inherit */
801 sig
->tty_old_pgrp
= NULL
;
803 sig
->utime
= sig
->stime
= sig
->cutime
= sig
->cstime
= cputime_zero
;
804 sig
->gtime
= cputime_zero
;
805 sig
->cgtime
= cputime_zero
;
806 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
807 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
808 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
809 #ifdef CONFIG_TASK_XACCT
810 sig
->rchar
= sig
->wchar
= sig
->syscr
= sig
->syscw
= 0;
812 #ifdef CONFIG_TASK_IO_ACCOUNTING
813 memset(&sig
->ioac
, 0, sizeof(sig
->ioac
));
815 sig
->sum_sched_runtime
= 0;
816 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
817 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
818 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
819 taskstats_tgid_init(sig
);
821 task_lock(current
->group_leader
);
822 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
823 task_unlock(current
->group_leader
);
825 if (sig
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
) {
827 * New sole thread in the process gets an expiry time
828 * of the whole CPU time limit.
830 tsk
->it_prof_expires
=
831 secs_to_cputime(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
833 acct_init_pacct(&sig
->pacct
);
840 void __cleanup_signal(struct signal_struct
*sig
)
842 exit_thread_group_keys(sig
);
843 kmem_cache_free(signal_cachep
, sig
);
846 static void cleanup_signal(struct task_struct
*tsk
)
848 struct signal_struct
*sig
= tsk
->signal
;
850 atomic_dec(&sig
->live
);
852 if (atomic_dec_and_test(&sig
->count
))
853 __cleanup_signal(sig
);
856 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
858 unsigned long new_flags
= p
->flags
;
860 new_flags
&= ~PF_SUPERPRIV
;
861 new_flags
|= PF_FORKNOEXEC
;
862 new_flags
|= PF_STARTING
;
863 p
->flags
= new_flags
;
864 clear_freeze_flag(p
);
867 asmlinkage
long sys_set_tid_address(int __user
*tidptr
)
869 current
->clear_child_tid
= tidptr
;
871 return task_pid_vnr(current
);
874 static void rt_mutex_init_task(struct task_struct
*p
)
876 spin_lock_init(&p
->pi_lock
);
877 #ifdef CONFIG_RT_MUTEXES
878 plist_head_init(&p
->pi_waiters
, &p
->pi_lock
);
879 p
->pi_blocked_on
= NULL
;
883 #ifdef CONFIG_MM_OWNER
884 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
888 #endif /* CONFIG_MM_OWNER */
891 * This creates a new process as a copy of the old one,
892 * but does not actually start it yet.
894 * It copies the registers, and all the appropriate
895 * parts of the process environment (as per the clone
896 * flags). The actual kick-off is left to the caller.
898 static struct task_struct
*copy_process(unsigned long clone_flags
,
899 unsigned long stack_start
,
900 struct pt_regs
*regs
,
901 unsigned long stack_size
,
902 int __user
*child_tidptr
,
907 struct task_struct
*p
;
908 int cgroup_callbacks_done
= 0;
910 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
911 return ERR_PTR(-EINVAL
);
914 * Thread groups must share signals as well, and detached threads
915 * can only be started up within the thread group.
917 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
918 return ERR_PTR(-EINVAL
);
921 * Shared signal handlers imply shared VM. By way of the above,
922 * thread groups also imply shared VM. Blocking this case allows
923 * for various simplifications in other code.
925 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
926 return ERR_PTR(-EINVAL
);
928 retval
= security_task_create(clone_flags
);
933 p
= dup_task_struct(current
);
937 rt_mutex_init_task(p
);
939 #ifdef CONFIG_PROVE_LOCKING
940 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
941 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
944 if (atomic_read(&p
->user
->processes
) >=
945 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
946 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
947 p
->user
!= current
->nsproxy
->user_ns
->root_user
)
951 atomic_inc(&p
->user
->__count
);
952 atomic_inc(&p
->user
->processes
);
953 get_group_info(p
->group_info
);
956 * If multiple threads are within copy_process(), then this check
957 * triggers too late. This doesn't hurt, the check is only there
958 * to stop root fork bombs.
960 if (nr_threads
>= max_threads
)
961 goto bad_fork_cleanup_count
;
963 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
964 goto bad_fork_cleanup_count
;
966 if (p
->binfmt
&& !try_module_get(p
->binfmt
->module
))
967 goto bad_fork_cleanup_put_domain
;
970 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
971 copy_flags(clone_flags
, p
);
972 INIT_LIST_HEAD(&p
->children
);
973 INIT_LIST_HEAD(&p
->sibling
);
974 #ifdef CONFIG_PREEMPT_RCU
975 p
->rcu_read_lock_nesting
= 0;
976 p
->rcu_flipctr_idx
= 0;
977 #endif /* #ifdef CONFIG_PREEMPT_RCU */
978 p
->vfork_done
= NULL
;
979 spin_lock_init(&p
->alloc_lock
);
981 clear_tsk_thread_flag(p
, TIF_SIGPENDING
);
982 init_sigpending(&p
->pending
);
984 p
->utime
= cputime_zero
;
985 p
->stime
= cputime_zero
;
986 p
->gtime
= cputime_zero
;
987 p
->utimescaled
= cputime_zero
;
988 p
->stimescaled
= cputime_zero
;
989 p
->prev_utime
= cputime_zero
;
990 p
->prev_stime
= cputime_zero
;
992 #ifdef CONFIG_DETECT_SOFTLOCKUP
993 p
->last_switch_count
= 0;
994 p
->last_switch_timestamp
= 0;
997 #ifdef CONFIG_TASK_XACCT
998 p
->rchar
= 0; /* I/O counter: bytes read */
999 p
->wchar
= 0; /* I/O counter: bytes written */
1000 p
->syscr
= 0; /* I/O counter: read syscalls */
1001 p
->syscw
= 0; /* I/O counter: write syscalls */
1003 task_io_accounting_init(p
);
1004 acct_clear_integrals(p
);
1006 p
->it_virt_expires
= cputime_zero
;
1007 p
->it_prof_expires
= cputime_zero
;
1008 p
->it_sched_expires
= 0;
1009 INIT_LIST_HEAD(&p
->cpu_timers
[0]);
1010 INIT_LIST_HEAD(&p
->cpu_timers
[1]);
1011 INIT_LIST_HEAD(&p
->cpu_timers
[2]);
1013 p
->lock_depth
= -1; /* -1 = no lock */
1014 do_posix_clock_monotonic_gettime(&p
->start_time
);
1015 p
->real_start_time
= p
->start_time
;
1016 monotonic_to_bootbased(&p
->real_start_time
);
1017 #ifdef CONFIG_SECURITY
1020 p
->cap_bset
= current
->cap_bset
;
1021 p
->io_context
= NULL
;
1022 p
->audit_context
= NULL
;
1025 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1026 if (IS_ERR(p
->mempolicy
)) {
1027 retval
= PTR_ERR(p
->mempolicy
);
1028 p
->mempolicy
= NULL
;
1029 goto bad_fork_cleanup_cgroup
;
1031 mpol_fix_fork_child_flag(p
);
1033 #ifdef CONFIG_TRACE_IRQFLAGS
1035 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1036 p
->hardirqs_enabled
= 1;
1038 p
->hardirqs_enabled
= 0;
1040 p
->hardirq_enable_ip
= 0;
1041 p
->hardirq_enable_event
= 0;
1042 p
->hardirq_disable_ip
= _THIS_IP_
;
1043 p
->hardirq_disable_event
= 0;
1044 p
->softirqs_enabled
= 1;
1045 p
->softirq_enable_ip
= _THIS_IP_
;
1046 p
->softirq_enable_event
= 0;
1047 p
->softirq_disable_ip
= 0;
1048 p
->softirq_disable_event
= 0;
1049 p
->hardirq_context
= 0;
1050 p
->softirq_context
= 0;
1052 #ifdef CONFIG_LOCKDEP
1053 p
->lockdep_depth
= 0; /* no locks held yet */
1054 p
->curr_chain_key
= 0;
1055 p
->lockdep_recursion
= 0;
1058 #ifdef CONFIG_DEBUG_MUTEXES
1059 p
->blocked_on
= NULL
; /* not blocked yet */
1062 /* Perform scheduler related setup. Assign this task to a CPU. */
1063 sched_fork(p
, clone_flags
);
1065 if ((retval
= security_task_alloc(p
)))
1066 goto bad_fork_cleanup_policy
;
1067 if ((retval
= audit_alloc(p
)))
1068 goto bad_fork_cleanup_security
;
1069 /* copy all the process information */
1070 if ((retval
= copy_semundo(clone_flags
, p
)))
1071 goto bad_fork_cleanup_audit
;
1072 if ((retval
= copy_files(clone_flags
, p
)))
1073 goto bad_fork_cleanup_semundo
;
1074 if ((retval
= copy_fs(clone_flags
, p
)))
1075 goto bad_fork_cleanup_files
;
1076 if ((retval
= copy_sighand(clone_flags
, p
)))
1077 goto bad_fork_cleanup_fs
;
1078 if ((retval
= copy_signal(clone_flags
, p
)))
1079 goto bad_fork_cleanup_sighand
;
1080 if ((retval
= copy_mm(clone_flags
, p
)))
1081 goto bad_fork_cleanup_signal
;
1082 if ((retval
= copy_keys(clone_flags
, p
)))
1083 goto bad_fork_cleanup_mm
;
1084 if ((retval
= copy_namespaces(clone_flags
, p
)))
1085 goto bad_fork_cleanup_keys
;
1086 if ((retval
= copy_io(clone_flags
, p
)))
1087 goto bad_fork_cleanup_namespaces
;
1088 retval
= copy_thread(0, clone_flags
, stack_start
, stack_size
, p
, regs
);
1090 goto bad_fork_cleanup_io
;
1092 if (pid
!= &init_struct_pid
) {
1094 pid
= alloc_pid(task_active_pid_ns(p
));
1096 goto bad_fork_cleanup_io
;
1098 if (clone_flags
& CLONE_NEWPID
) {
1099 retval
= pid_ns_prepare_proc(task_active_pid_ns(p
));
1101 goto bad_fork_free_pid
;
1105 p
->pid
= pid_nr(pid
);
1107 if (clone_flags
& CLONE_THREAD
)
1108 p
->tgid
= current
->tgid
;
1110 if (current
->nsproxy
!= p
->nsproxy
) {
1111 retval
= ns_cgroup_clone(p
, pid
);
1113 goto bad_fork_free_pid
;
1116 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1118 * Clear TID on mm_release()?
1120 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1122 p
->robust_list
= NULL
;
1123 #ifdef CONFIG_COMPAT
1124 p
->compat_robust_list
= NULL
;
1126 INIT_LIST_HEAD(&p
->pi_state_list
);
1127 p
->pi_state_cache
= NULL
;
1130 * sigaltstack should be cleared when sharing the same VM
1132 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1133 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1136 * Syscall tracing should be turned off in the child regardless
1139 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1140 #ifdef TIF_SYSCALL_EMU
1141 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1143 clear_all_latency_tracing(p
);
1145 /* Our parent execution domain becomes current domain
1146 These must match for thread signalling to apply */
1147 p
->parent_exec_id
= p
->self_exec_id
;
1149 /* ok, now we should be set up.. */
1150 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1151 p
->pdeath_signal
= 0;
1155 * Ok, make it visible to the rest of the system.
1156 * We dont wake it up yet.
1158 p
->group_leader
= p
;
1159 INIT_LIST_HEAD(&p
->thread_group
);
1161 /* Now that the task is set up, run cgroup callbacks if
1162 * necessary. We need to run them before the task is visible
1163 * on the tasklist. */
1164 cgroup_fork_callbacks(p
);
1165 cgroup_callbacks_done
= 1;
1167 /* Need tasklist lock for parent etc handling! */
1168 write_lock_irq(&tasklist_lock
);
1171 * The task hasn't been attached yet, so its cpus_allowed mask will
1172 * not be changed, nor will its assigned CPU.
1174 * The cpus_allowed mask of the parent may have changed after it was
1175 * copied first time - so re-copy it here, then check the child's CPU
1176 * to ensure it is on a valid CPU (and if not, just force it back to
1177 * parent's CPU). This avoids alot of nasty races.
1179 p
->cpus_allowed
= current
->cpus_allowed
;
1180 p
->rt
.nr_cpus_allowed
= current
->rt
.nr_cpus_allowed
;
1181 if (unlikely(!cpu_isset(task_cpu(p
), p
->cpus_allowed
) ||
1182 !cpu_online(task_cpu(p
))))
1183 set_task_cpu(p
, smp_processor_id());
1185 /* CLONE_PARENT re-uses the old parent */
1186 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
))
1187 p
->real_parent
= current
->real_parent
;
1189 p
->real_parent
= current
;
1191 spin_lock(¤t
->sighand
->siglock
);
1194 * Process group and session signals need to be delivered to just the
1195 * parent before the fork or both the parent and the child after the
1196 * fork. Restart if a signal comes in before we add the new process to
1197 * it's process group.
1198 * A fatal signal pending means that current will exit, so the new
1199 * thread can't slip out of an OOM kill (or normal SIGKILL).
1201 recalc_sigpending();
1202 if (signal_pending(current
)) {
1203 spin_unlock(¤t
->sighand
->siglock
);
1204 write_unlock_irq(&tasklist_lock
);
1205 retval
= -ERESTARTNOINTR
;
1206 goto bad_fork_free_pid
;
1209 if (clone_flags
& CLONE_THREAD
) {
1210 p
->group_leader
= current
->group_leader
;
1211 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1213 if (!cputime_eq(current
->signal
->it_virt_expires
,
1215 !cputime_eq(current
->signal
->it_prof_expires
,
1217 current
->signal
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
||
1218 !list_empty(¤t
->signal
->cpu_timers
[0]) ||
1219 !list_empty(¤t
->signal
->cpu_timers
[1]) ||
1220 !list_empty(¤t
->signal
->cpu_timers
[2])) {
1222 * Have child wake up on its first tick to check
1223 * for process CPU timers.
1225 p
->it_prof_expires
= jiffies_to_cputime(1);
1229 if (likely(p
->pid
)) {
1230 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1231 tracehook_finish_clone(p
, clone_flags
, trace
);
1233 if (thread_group_leader(p
)) {
1234 if (clone_flags
& CLONE_NEWPID
)
1235 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1237 p
->signal
->leader_pid
= pid
;
1238 p
->signal
->tty
= current
->signal
->tty
;
1239 set_task_pgrp(p
, task_pgrp_nr(current
));
1240 set_task_session(p
, task_session_nr(current
));
1241 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1242 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1243 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1244 __get_cpu_var(process_counts
)++;
1246 attach_pid(p
, PIDTYPE_PID
, pid
);
1251 spin_unlock(¤t
->sighand
->siglock
);
1252 write_unlock_irq(&tasklist_lock
);
1253 proc_fork_connector(p
);
1254 cgroup_post_fork(p
);
1258 if (pid
!= &init_struct_pid
)
1260 bad_fork_cleanup_io
:
1261 put_io_context(p
->io_context
);
1262 bad_fork_cleanup_namespaces
:
1263 exit_task_namespaces(p
);
1264 bad_fork_cleanup_keys
:
1266 bad_fork_cleanup_mm
:
1269 bad_fork_cleanup_signal
:
1271 bad_fork_cleanup_sighand
:
1272 __cleanup_sighand(p
->sighand
);
1273 bad_fork_cleanup_fs
:
1274 exit_fs(p
); /* blocking */
1275 bad_fork_cleanup_files
:
1276 exit_files(p
); /* blocking */
1277 bad_fork_cleanup_semundo
:
1279 bad_fork_cleanup_audit
:
1281 bad_fork_cleanup_security
:
1282 security_task_free(p
);
1283 bad_fork_cleanup_policy
:
1285 mpol_put(p
->mempolicy
);
1286 bad_fork_cleanup_cgroup
:
1288 cgroup_exit(p
, cgroup_callbacks_done
);
1289 delayacct_tsk_free(p
);
1291 module_put(p
->binfmt
->module
);
1292 bad_fork_cleanup_put_domain
:
1293 module_put(task_thread_info(p
)->exec_domain
->module
);
1294 bad_fork_cleanup_count
:
1295 put_group_info(p
->group_info
);
1296 atomic_dec(&p
->user
->processes
);
1301 return ERR_PTR(retval
);
1304 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1306 memset(regs
, 0, sizeof(struct pt_regs
));
1310 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1312 struct task_struct
*task
;
1313 struct pt_regs regs
;
1315 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1316 &init_struct_pid
, 0);
1318 init_idle(task
, cpu
);
1324 * Ok, this is the main fork-routine.
1326 * It copies the process, and if successful kick-starts
1327 * it and waits for it to finish using the VM if required.
1329 long do_fork(unsigned long clone_flags
,
1330 unsigned long stack_start
,
1331 struct pt_regs
*regs
,
1332 unsigned long stack_size
,
1333 int __user
*parent_tidptr
,
1334 int __user
*child_tidptr
)
1336 struct task_struct
*p
;
1341 * We hope to recycle these flags after 2.6.26
1343 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1344 static int __read_mostly count
= 100;
1346 if (count
> 0 && printk_ratelimit()) {
1347 char comm
[TASK_COMM_LEN
];
1350 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1351 "clone flags 0x%lx\n",
1352 get_task_comm(comm
, current
),
1353 clone_flags
& CLONE_STOPPED
);
1358 * When called from kernel_thread, don't do user tracing stuff.
1360 if (likely(user_mode(regs
)))
1361 trace
= tracehook_prepare_clone(clone_flags
);
1363 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1364 child_tidptr
, NULL
, trace
);
1366 * Do this prior waking up the new thread - the thread pointer
1367 * might get invalid after that point, if the thread exits quickly.
1370 struct completion vfork
;
1372 nr
= task_pid_vnr(p
);
1374 if (clone_flags
& CLONE_PARENT_SETTID
)
1375 put_user(nr
, parent_tidptr
);
1377 if (clone_flags
& CLONE_VFORK
) {
1378 p
->vfork_done
= &vfork
;
1379 init_completion(&vfork
);
1382 tracehook_report_clone(trace
, regs
, clone_flags
, nr
, p
);
1385 * We set PF_STARTING at creation in case tracing wants to
1386 * use this to distinguish a fully live task from one that
1387 * hasn't gotten to tracehook_report_clone() yet. Now we
1388 * clear it and set the child going.
1390 p
->flags
&= ~PF_STARTING
;
1392 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1394 * We'll start up with an immediate SIGSTOP.
1396 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1397 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1398 __set_task_state(p
, TASK_STOPPED
);
1400 wake_up_new_task(p
, clone_flags
);
1403 tracehook_report_clone_complete(trace
, regs
,
1404 clone_flags
, nr
, p
);
1406 if (clone_flags
& CLONE_VFORK
) {
1407 freezer_do_not_count();
1408 wait_for_completion(&vfork
);
1410 tracehook_report_vfork_done(p
, nr
);
1418 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1419 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1422 static void sighand_ctor(void *data
)
1424 struct sighand_struct
*sighand
= data
;
1426 spin_lock_init(&sighand
->siglock
);
1427 init_waitqueue_head(&sighand
->signalfd_wqh
);
1430 void __init
proc_caches_init(void)
1432 sighand_cachep
= kmem_cache_create("sighand_cache",
1433 sizeof(struct sighand_struct
), 0,
1434 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
,
1436 signal_cachep
= kmem_cache_create("signal_cache",
1437 sizeof(struct signal_struct
), 0,
1438 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1439 files_cachep
= kmem_cache_create("files_cache",
1440 sizeof(struct files_struct
), 0,
1441 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1442 fs_cachep
= kmem_cache_create("fs_cache",
1443 sizeof(struct fs_struct
), 0,
1444 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1445 vm_area_cachep
= kmem_cache_create("vm_area_struct",
1446 sizeof(struct vm_area_struct
), 0,
1448 mm_cachep
= kmem_cache_create("mm_struct",
1449 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1450 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1454 * Check constraints on flags passed to the unshare system call and
1455 * force unsharing of additional process context as appropriate.
1457 static void check_unshare_flags(unsigned long *flags_ptr
)
1460 * If unsharing a thread from a thread group, must also
1463 if (*flags_ptr
& CLONE_THREAD
)
1464 *flags_ptr
|= CLONE_VM
;
1467 * If unsharing vm, must also unshare signal handlers.
1469 if (*flags_ptr
& CLONE_VM
)
1470 *flags_ptr
|= CLONE_SIGHAND
;
1473 * If unsharing signal handlers and the task was created
1474 * using CLONE_THREAD, then must unshare the thread
1476 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1477 (atomic_read(¤t
->signal
->count
) > 1))
1478 *flags_ptr
|= CLONE_THREAD
;
1481 * If unsharing namespace, must also unshare filesystem information.
1483 if (*flags_ptr
& CLONE_NEWNS
)
1484 *flags_ptr
|= CLONE_FS
;
1488 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1490 static int unshare_thread(unsigned long unshare_flags
)
1492 if (unshare_flags
& CLONE_THREAD
)
1499 * Unshare the filesystem structure if it is being shared
1501 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1503 struct fs_struct
*fs
= current
->fs
;
1505 if ((unshare_flags
& CLONE_FS
) &&
1506 (fs
&& atomic_read(&fs
->count
) > 1)) {
1507 *new_fsp
= __copy_fs_struct(current
->fs
);
1516 * Unsharing of sighand is not supported yet
1518 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1520 struct sighand_struct
*sigh
= current
->sighand
;
1522 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1529 * Unshare vm if it is being shared
1531 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1533 struct mm_struct
*mm
= current
->mm
;
1535 if ((unshare_flags
& CLONE_VM
) &&
1536 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1544 * Unshare file descriptor table if it is being shared
1546 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1548 struct files_struct
*fd
= current
->files
;
1551 if ((unshare_flags
& CLONE_FILES
) &&
1552 (fd
&& atomic_read(&fd
->count
) > 1)) {
1553 *new_fdp
= dup_fd(fd
, &error
);
1562 * unshare allows a process to 'unshare' part of the process
1563 * context which was originally shared using clone. copy_*
1564 * functions used by do_fork() cannot be used here directly
1565 * because they modify an inactive task_struct that is being
1566 * constructed. Here we are modifying the current, active,
1569 asmlinkage
long sys_unshare(unsigned long unshare_flags
)
1572 struct fs_struct
*fs
, *new_fs
= NULL
;
1573 struct sighand_struct
*new_sigh
= NULL
;
1574 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1575 struct files_struct
*fd
, *new_fd
= NULL
;
1576 struct nsproxy
*new_nsproxy
= NULL
;
1579 check_unshare_flags(&unshare_flags
);
1581 /* Return -EINVAL for all unsupported flags */
1583 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1584 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1585 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWUSER
|
1587 goto bad_unshare_out
;
1590 * CLONE_NEWIPC must also detach from the undolist: after switching
1591 * to a new ipc namespace, the semaphore arrays from the old
1592 * namespace are unreachable.
1594 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1596 if ((err
= unshare_thread(unshare_flags
)))
1597 goto bad_unshare_out
;
1598 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1599 goto bad_unshare_cleanup_thread
;
1600 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1601 goto bad_unshare_cleanup_fs
;
1602 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1603 goto bad_unshare_cleanup_sigh
;
1604 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1605 goto bad_unshare_cleanup_vm
;
1606 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1608 goto bad_unshare_cleanup_fd
;
1610 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1613 * CLONE_SYSVSEM is equivalent to sys_exit().
1619 switch_task_namespaces(current
, new_nsproxy
);
1627 current
->fs
= new_fs
;
1633 active_mm
= current
->active_mm
;
1634 current
->mm
= new_mm
;
1635 current
->active_mm
= new_mm
;
1636 activate_mm(active_mm
, new_mm
);
1641 fd
= current
->files
;
1642 current
->files
= new_fd
;
1646 task_unlock(current
);
1650 put_nsproxy(new_nsproxy
);
1652 bad_unshare_cleanup_fd
:
1654 put_files_struct(new_fd
);
1656 bad_unshare_cleanup_vm
:
1660 bad_unshare_cleanup_sigh
:
1662 if (atomic_dec_and_test(&new_sigh
->count
))
1663 kmem_cache_free(sighand_cachep
, new_sigh
);
1665 bad_unshare_cleanup_fs
:
1667 put_fs_struct(new_fs
);
1669 bad_unshare_cleanup_thread
:
1675 * Helper to unshare the files of the current task.
1676 * We don't want to expose copy_files internals to
1677 * the exec layer of the kernel.
1680 int unshare_files(struct files_struct
**displaced
)
1682 struct task_struct
*task
= current
;
1683 struct files_struct
*copy
= NULL
;
1686 error
= unshare_fd(CLONE_FILES
, ©
);
1687 if (error
|| !copy
) {
1691 *displaced
= task
->files
;