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>
30 #include <linux/mmu_notifier.h>
32 #include <linux/nsproxy.h>
33 #include <linux/capability.h>
34 #include <linux/cpu.h>
35 #include <linux/cgroup.h>
36 #include <linux/security.h>
37 #include <linux/hugetlb.h>
38 #include <linux/swap.h>
39 #include <linux/syscalls.h>
40 #include <linux/jiffies.h>
41 #include <linux/tracehook.h>
42 #include <linux/futex.h>
43 #include <linux/task_io_accounting_ops.h>
44 #include <linux/rcupdate.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/audit.h>
48 #include <linux/memcontrol.h>
49 #include <linux/profile.h>
50 #include <linux/rmap.h>
51 #include <linux/acct.h>
52 #include <linux/tsacct_kern.h>
53 #include <linux/cn_proc.h>
54 #include <linux/freezer.h>
55 #include <linux/delayacct.h>
56 #include <linux/taskstats_kern.h>
57 #include <linux/random.h>
58 #include <linux/tty.h>
59 #include <linux/proc_fs.h>
60 #include <linux/blkdev.h>
61 #include <trace/sched.h>
63 #include <asm/pgtable.h>
64 #include <asm/pgalloc.h>
65 #include <asm/uaccess.h>
66 #include <asm/mmu_context.h>
67 #include <asm/cacheflush.h>
68 #include <asm/tlbflush.h>
71 * Protected counters by write_lock_irq(&tasklist_lock)
73 unsigned long total_forks
; /* Handle normal Linux uptimes. */
74 int nr_threads
; /* The idle threads do not count.. */
76 int max_threads
; /* tunable limit on nr_threads */
78 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
80 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
82 DEFINE_TRACE(sched_process_fork
);
84 int nr_processes(void)
89 for_each_online_cpu(cpu
)
90 total
+= per_cpu(process_counts
, cpu
);
95 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
96 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
97 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
98 static struct kmem_cache
*task_struct_cachep
;
101 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
102 static inline struct thread_info
*alloc_thread_info(struct task_struct
*tsk
)
104 #ifdef CONFIG_DEBUG_STACK_USAGE
105 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
107 gfp_t mask
= GFP_KERNEL
;
109 return (struct thread_info
*)__get_free_pages(mask
, THREAD_SIZE_ORDER
);
112 static inline void free_thread_info(struct thread_info
*ti
)
114 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
118 /* SLAB cache for signal_struct structures (tsk->signal) */
119 static struct kmem_cache
*signal_cachep
;
121 /* SLAB cache for sighand_struct structures (tsk->sighand) */
122 struct kmem_cache
*sighand_cachep
;
124 /* SLAB cache for files_struct structures (tsk->files) */
125 struct kmem_cache
*files_cachep
;
127 /* SLAB cache for fs_struct structures (tsk->fs) */
128 struct kmem_cache
*fs_cachep
;
130 /* SLAB cache for vm_area_struct structures */
131 struct kmem_cache
*vm_area_cachep
;
133 /* SLAB cache for mm_struct structures (tsk->mm) */
134 static struct kmem_cache
*mm_cachep
;
136 void free_task(struct task_struct
*tsk
)
138 prop_local_destroy_single(&tsk
->dirties
);
139 free_thread_info(tsk
->stack
);
140 rt_mutex_debug_task_free(tsk
);
141 free_task_struct(tsk
);
143 EXPORT_SYMBOL(free_task
);
145 void __put_task_struct(struct task_struct
*tsk
)
147 WARN_ON(!tsk
->exit_state
);
148 WARN_ON(atomic_read(&tsk
->usage
));
149 WARN_ON(tsk
== current
);
151 security_task_free(tsk
);
153 put_group_info(tsk
->group_info
);
154 delayacct_tsk_free(tsk
);
156 if (!profile_handoff_task(tsk
))
161 * macro override instead of weak attribute alias, to workaround
162 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
164 #ifndef arch_task_cache_init
165 #define arch_task_cache_init()
168 void __init
fork_init(unsigned long mempages
)
170 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
171 #ifndef ARCH_MIN_TASKALIGN
172 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
174 /* create a slab on which task_structs can be allocated */
176 kmem_cache_create("task_struct", sizeof(struct task_struct
),
177 ARCH_MIN_TASKALIGN
, SLAB_PANIC
, NULL
);
180 /* do the arch specific task caches init */
181 arch_task_cache_init();
184 * The default maximum number of threads is set to a safe
185 * value: the thread structures can take up at most half
188 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
191 * we need to allow at least 20 threads to boot a system
196 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
197 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
198 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
199 init_task
.signal
->rlim
[RLIMIT_NPROC
];
202 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
203 struct task_struct
*src
)
209 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
211 struct task_struct
*tsk
;
212 struct thread_info
*ti
;
215 prepare_to_copy(orig
);
217 tsk
= alloc_task_struct();
221 ti
= alloc_thread_info(tsk
);
223 free_task_struct(tsk
);
227 err
= arch_dup_task_struct(tsk
, orig
);
233 err
= prop_local_init_single(&tsk
->dirties
);
237 setup_thread_stack(tsk
, orig
);
239 #ifdef CONFIG_CC_STACKPROTECTOR
240 tsk
->stack_canary
= get_random_int();
243 /* One for us, one for whoever does the "release_task()" (usually parent) */
244 atomic_set(&tsk
->usage
,2);
245 atomic_set(&tsk
->fs_excl
, 0);
246 #ifdef CONFIG_BLK_DEV_IO_TRACE
249 tsk
->splice_pipe
= NULL
;
253 free_thread_info(ti
);
254 free_task_struct(tsk
);
259 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
261 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
262 struct rb_node
**rb_link
, *rb_parent
;
264 unsigned long charge
;
265 struct mempolicy
*pol
;
267 down_write(&oldmm
->mmap_sem
);
268 flush_cache_dup_mm(oldmm
);
270 * Not linked in yet - no deadlock potential:
272 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
276 mm
->mmap_cache
= NULL
;
277 mm
->free_area_cache
= oldmm
->mmap_base
;
278 mm
->cached_hole_size
= ~0UL;
280 cpus_clear(mm
->cpu_vm_mask
);
282 rb_link
= &mm
->mm_rb
.rb_node
;
286 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
289 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
290 long pages
= vma_pages(mpnt
);
291 mm
->total_vm
-= pages
;
292 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
297 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
298 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
299 if (security_vm_enough_memory(len
))
303 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
307 pol
= mpol_dup(vma_policy(mpnt
));
308 retval
= PTR_ERR(pol
);
310 goto fail_nomem_policy
;
311 vma_set_policy(tmp
, pol
);
312 tmp
->vm_flags
&= ~VM_LOCKED
;
318 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
320 if (tmp
->vm_flags
& VM_DENYWRITE
)
321 atomic_dec(&inode
->i_writecount
);
323 /* insert tmp into the share list, just after mpnt */
324 spin_lock(&file
->f_mapping
->i_mmap_lock
);
325 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
326 flush_dcache_mmap_lock(file
->f_mapping
);
327 vma_prio_tree_add(tmp
, mpnt
);
328 flush_dcache_mmap_unlock(file
->f_mapping
);
329 spin_unlock(&file
->f_mapping
->i_mmap_lock
);
333 * Clear hugetlb-related page reserves for children. This only
334 * affects MAP_PRIVATE mappings. Faults generated by the child
335 * are not guaranteed to succeed, even if read-only
337 if (is_vm_hugetlb_page(tmp
))
338 reset_vma_resv_huge_pages(tmp
);
341 * Link in the new vma and copy the page table entries.
344 pprev
= &tmp
->vm_next
;
346 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
347 rb_link
= &tmp
->vm_rb
.rb_right
;
348 rb_parent
= &tmp
->vm_rb
;
351 retval
= copy_page_range(mm
, oldmm
, mpnt
);
353 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
354 tmp
->vm_ops
->open(tmp
);
359 /* a new mm has just been created */
360 arch_dup_mmap(oldmm
, mm
);
363 up_write(&mm
->mmap_sem
);
365 up_write(&oldmm
->mmap_sem
);
368 kmem_cache_free(vm_area_cachep
, tmp
);
371 vm_unacct_memory(charge
);
375 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
377 mm
->pgd
= pgd_alloc(mm
);
378 if (unlikely(!mm
->pgd
))
383 static inline void mm_free_pgd(struct mm_struct
* mm
)
385 pgd_free(mm
, mm
->pgd
);
388 #define dup_mmap(mm, oldmm) (0)
389 #define mm_alloc_pgd(mm) (0)
390 #define mm_free_pgd(mm)
391 #endif /* CONFIG_MMU */
393 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
395 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
396 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
398 #include <linux/init_task.h>
400 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
402 atomic_set(&mm
->mm_users
, 1);
403 atomic_set(&mm
->mm_count
, 1);
404 init_rwsem(&mm
->mmap_sem
);
405 INIT_LIST_HEAD(&mm
->mmlist
);
406 mm
->flags
= (current
->mm
) ? current
->mm
->flags
407 : MMF_DUMP_FILTER_DEFAULT
;
408 mm
->core_state
= NULL
;
410 set_mm_counter(mm
, file_rss
, 0);
411 set_mm_counter(mm
, anon_rss
, 0);
412 spin_lock_init(&mm
->page_table_lock
);
413 rwlock_init(&mm
->ioctx_list_lock
);
414 mm
->ioctx_list
= NULL
;
415 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
416 mm
->cached_hole_size
= ~0UL;
417 mm_init_owner(mm
, p
);
419 if (likely(!mm_alloc_pgd(mm
))) {
421 mmu_notifier_mm_init(mm
);
430 * Allocate and initialize an mm_struct.
432 struct mm_struct
* mm_alloc(void)
434 struct mm_struct
* mm
;
438 memset(mm
, 0, sizeof(*mm
));
439 mm
= mm_init(mm
, current
);
445 * Called when the last reference to the mm
446 * is dropped: either by a lazy thread or by
447 * mmput. Free the page directory and the mm.
449 void __mmdrop(struct mm_struct
*mm
)
451 BUG_ON(mm
== &init_mm
);
454 mmu_notifier_mm_destroy(mm
);
457 EXPORT_SYMBOL_GPL(__mmdrop
);
460 * Decrement the use count and release all resources for an mm.
462 void mmput(struct mm_struct
*mm
)
466 if (atomic_dec_and_test(&mm
->mm_users
)) {
469 set_mm_exe_file(mm
, NULL
);
470 if (!list_empty(&mm
->mmlist
)) {
471 spin_lock(&mmlist_lock
);
472 list_del(&mm
->mmlist
);
473 spin_unlock(&mmlist_lock
);
479 EXPORT_SYMBOL_GPL(mmput
);
482 * get_task_mm - acquire a reference to the task's mm
484 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
485 * this kernel workthread has transiently adopted a user mm with use_mm,
486 * to do its AIO) is not set and if so returns a reference to it, after
487 * bumping up the use count. User must release the mm via mmput()
488 * after use. Typically used by /proc and ptrace.
490 struct mm_struct
*get_task_mm(struct task_struct
*task
)
492 struct mm_struct
*mm
;
497 if (task
->flags
& PF_KTHREAD
)
500 atomic_inc(&mm
->mm_users
);
505 EXPORT_SYMBOL_GPL(get_task_mm
);
507 /* Please note the differences between mmput and mm_release.
508 * mmput is called whenever we stop holding onto a mm_struct,
509 * error success whatever.
511 * mm_release is called after a mm_struct has been removed
512 * from the current process.
514 * This difference is important for error handling, when we
515 * only half set up a mm_struct for a new process and need to restore
516 * the old one. Because we mmput the new mm_struct before
517 * restoring the old one. . .
518 * Eric Biederman 10 January 1998
520 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
522 struct completion
*vfork_done
= tsk
->vfork_done
;
524 /* Get rid of any cached register state */
525 deactivate_mm(tsk
, mm
);
527 /* notify parent sleeping on vfork() */
529 tsk
->vfork_done
= NULL
;
530 complete(vfork_done
);
534 * If we're exiting normally, clear a user-space tid field if
535 * requested. We leave this alone when dying by signal, to leave
536 * the value intact in a core dump, and to save the unnecessary
537 * trouble otherwise. Userland only wants this done for a sys_exit.
539 if (tsk
->clear_child_tid
540 && !(tsk
->flags
& PF_SIGNALED
)
541 && atomic_read(&mm
->mm_users
) > 1) {
542 u32 __user
* tidptr
= tsk
->clear_child_tid
;
543 tsk
->clear_child_tid
= NULL
;
546 * We don't check the error code - if userspace has
547 * not set up a proper pointer then tough luck.
550 sys_futex(tidptr
, FUTEX_WAKE
, 1, NULL
, NULL
, 0);
555 * Allocate a new mm structure and copy contents from the
556 * mm structure of the passed in task structure.
558 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
560 struct mm_struct
*mm
, *oldmm
= current
->mm
;
570 memcpy(mm
, oldmm
, sizeof(*mm
));
572 /* Initializing for Swap token stuff */
573 mm
->token_priority
= 0;
574 mm
->last_interval
= 0;
576 if (!mm_init(mm
, tsk
))
579 if (init_new_context(tsk
, mm
))
582 dup_mm_exe_file(oldmm
, mm
);
584 err
= dup_mmap(mm
, oldmm
);
588 mm
->hiwater_rss
= get_mm_rss(mm
);
589 mm
->hiwater_vm
= mm
->total_vm
;
601 * If init_new_context() failed, we cannot use mmput() to free the mm
602 * because it calls destroy_context()
609 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
611 struct mm_struct
* mm
, *oldmm
;
614 tsk
->min_flt
= tsk
->maj_flt
= 0;
615 tsk
->nvcsw
= tsk
->nivcsw
= 0;
618 tsk
->active_mm
= NULL
;
621 * Are we cloning a kernel thread?
623 * We need to steal a active VM for that..
629 if (clone_flags
& CLONE_VM
) {
630 atomic_inc(&oldmm
->mm_users
);
641 /* Initializing for Swap token stuff */
642 mm
->token_priority
= 0;
643 mm
->last_interval
= 0;
653 static struct fs_struct
*__copy_fs_struct(struct fs_struct
*old
)
655 struct fs_struct
*fs
= kmem_cache_alloc(fs_cachep
, GFP_KERNEL
);
656 /* We don't need to lock fs - think why ;-) */
658 atomic_set(&fs
->count
, 1);
659 rwlock_init(&fs
->lock
);
660 fs
->umask
= old
->umask
;
661 read_lock(&old
->lock
);
662 fs
->root
= old
->root
;
663 path_get(&old
->root
);
666 read_unlock(&old
->lock
);
671 struct fs_struct
*copy_fs_struct(struct fs_struct
*old
)
673 return __copy_fs_struct(old
);
676 EXPORT_SYMBOL_GPL(copy_fs_struct
);
678 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
680 if (clone_flags
& CLONE_FS
) {
681 atomic_inc(¤t
->fs
->count
);
684 tsk
->fs
= __copy_fs_struct(current
->fs
);
690 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
692 struct files_struct
*oldf
, *newf
;
696 * A background process may not have any files ...
698 oldf
= current
->files
;
702 if (clone_flags
& CLONE_FILES
) {
703 atomic_inc(&oldf
->count
);
707 newf
= dup_fd(oldf
, &error
);
717 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
720 struct io_context
*ioc
= current
->io_context
;
725 * Share io context with parent, if CLONE_IO is set
727 if (clone_flags
& CLONE_IO
) {
728 tsk
->io_context
= ioc_task_link(ioc
);
729 if (unlikely(!tsk
->io_context
))
731 } else if (ioprio_valid(ioc
->ioprio
)) {
732 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
733 if (unlikely(!tsk
->io_context
))
736 tsk
->io_context
->ioprio
= ioc
->ioprio
;
742 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
744 struct sighand_struct
*sig
;
746 if (clone_flags
& (CLONE_SIGHAND
| CLONE_THREAD
)) {
747 atomic_inc(¤t
->sighand
->count
);
750 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
751 rcu_assign_pointer(tsk
->sighand
, sig
);
754 atomic_set(&sig
->count
, 1);
755 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
759 void __cleanup_sighand(struct sighand_struct
*sighand
)
761 if (atomic_dec_and_test(&sighand
->count
))
762 kmem_cache_free(sighand_cachep
, sighand
);
767 * Initialize POSIX timer handling for a thread group.
769 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
771 /* Thread group counters. */
772 thread_group_cputime_init(sig
);
774 /* Expiration times and increments. */
775 sig
->it_virt_expires
= cputime_zero
;
776 sig
->it_virt_incr
= cputime_zero
;
777 sig
->it_prof_expires
= cputime_zero
;
778 sig
->it_prof_incr
= cputime_zero
;
780 /* Cached expiration times. */
781 sig
->cputime_expires
.prof_exp
= cputime_zero
;
782 sig
->cputime_expires
.virt_exp
= cputime_zero
;
783 sig
->cputime_expires
.sched_exp
= 0;
785 /* The timer lists. */
786 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
787 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
788 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
791 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
793 struct signal_struct
*sig
;
796 if (clone_flags
& CLONE_THREAD
) {
797 ret
= thread_group_cputime_clone_thread(current
);
799 atomic_inc(¤t
->signal
->count
);
800 atomic_inc(¤t
->signal
->live
);
804 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
809 ret
= copy_thread_group_keys(tsk
);
811 kmem_cache_free(signal_cachep
, sig
);
815 atomic_set(&sig
->count
, 1);
816 atomic_set(&sig
->live
, 1);
817 init_waitqueue_head(&sig
->wait_chldexit
);
819 sig
->group_exit_code
= 0;
820 sig
->group_exit_task
= NULL
;
821 sig
->group_stop_count
= 0;
822 sig
->curr_target
= tsk
;
823 init_sigpending(&sig
->shared_pending
);
824 INIT_LIST_HEAD(&sig
->posix_timers
);
826 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
827 sig
->it_real_incr
.tv64
= 0;
828 sig
->real_timer
.function
= it_real_fn
;
830 sig
->leader
= 0; /* session leadership doesn't inherit */
831 sig
->tty_old_pgrp
= NULL
;
834 sig
->cutime
= sig
->cstime
= cputime_zero
;
835 sig
->gtime
= cputime_zero
;
836 sig
->cgtime
= cputime_zero
;
837 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
838 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
839 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
840 task_io_accounting_init(&sig
->ioac
);
841 taskstats_tgid_init(sig
);
843 task_lock(current
->group_leader
);
844 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
845 task_unlock(current
->group_leader
);
847 posix_cpu_timers_init_group(sig
);
849 acct_init_pacct(&sig
->pacct
);
856 void __cleanup_signal(struct signal_struct
*sig
)
858 thread_group_cputime_free(sig
);
859 exit_thread_group_keys(sig
);
860 tty_kref_put(sig
->tty
);
861 kmem_cache_free(signal_cachep
, sig
);
864 static void cleanup_signal(struct task_struct
*tsk
)
866 struct signal_struct
*sig
= tsk
->signal
;
868 atomic_dec(&sig
->live
);
870 if (atomic_dec_and_test(&sig
->count
))
871 __cleanup_signal(sig
);
874 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
876 unsigned long new_flags
= p
->flags
;
878 new_flags
&= ~PF_SUPERPRIV
;
879 new_flags
|= PF_FORKNOEXEC
;
880 new_flags
|= PF_STARTING
;
881 p
->flags
= new_flags
;
882 clear_freeze_flag(p
);
885 asmlinkage
long sys_set_tid_address(int __user
*tidptr
)
887 current
->clear_child_tid
= tidptr
;
889 return task_pid_vnr(current
);
892 static void rt_mutex_init_task(struct task_struct
*p
)
894 spin_lock_init(&p
->pi_lock
);
895 #ifdef CONFIG_RT_MUTEXES
896 plist_head_init(&p
->pi_waiters
, &p
->pi_lock
);
897 p
->pi_blocked_on
= NULL
;
901 #ifdef CONFIG_MM_OWNER
902 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
906 #endif /* CONFIG_MM_OWNER */
909 * Initialize POSIX timer handling for a single task.
911 static void posix_cpu_timers_init(struct task_struct
*tsk
)
913 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
914 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
915 tsk
->cputime_expires
.sched_exp
= 0;
916 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
917 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
918 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
922 * This creates a new process as a copy of the old one,
923 * but does not actually start it yet.
925 * It copies the registers, and all the appropriate
926 * parts of the process environment (as per the clone
927 * flags). The actual kick-off is left to the caller.
929 static struct task_struct
*copy_process(unsigned long clone_flags
,
930 unsigned long stack_start
,
931 struct pt_regs
*regs
,
932 unsigned long stack_size
,
933 int __user
*child_tidptr
,
938 struct task_struct
*p
;
939 int cgroup_callbacks_done
= 0;
941 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
942 return ERR_PTR(-EINVAL
);
945 * Thread groups must share signals as well, and detached threads
946 * can only be started up within the thread group.
948 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
949 return ERR_PTR(-EINVAL
);
952 * Shared signal handlers imply shared VM. By way of the above,
953 * thread groups also imply shared VM. Blocking this case allows
954 * for various simplifications in other code.
956 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
957 return ERR_PTR(-EINVAL
);
959 retval
= security_task_create(clone_flags
);
964 p
= dup_task_struct(current
);
968 rt_mutex_init_task(p
);
970 #ifdef CONFIG_PROVE_LOCKING
971 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
972 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
975 if (atomic_read(&p
->user
->processes
) >=
976 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
977 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
978 p
->user
!= current
->nsproxy
->user_ns
->root_user
)
982 atomic_inc(&p
->user
->__count
);
983 atomic_inc(&p
->user
->processes
);
984 get_group_info(p
->group_info
);
987 * If multiple threads are within copy_process(), then this check
988 * triggers too late. This doesn't hurt, the check is only there
989 * to stop root fork bombs.
991 if (nr_threads
>= max_threads
)
992 goto bad_fork_cleanup_count
;
994 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
995 goto bad_fork_cleanup_count
;
997 if (p
->binfmt
&& !try_module_get(p
->binfmt
->module
))
998 goto bad_fork_cleanup_put_domain
;
1001 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1002 copy_flags(clone_flags
, p
);
1003 INIT_LIST_HEAD(&p
->children
);
1004 INIT_LIST_HEAD(&p
->sibling
);
1005 #ifdef CONFIG_PREEMPT_RCU
1006 p
->rcu_read_lock_nesting
= 0;
1007 p
->rcu_flipctr_idx
= 0;
1008 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1009 p
->vfork_done
= NULL
;
1010 spin_lock_init(&p
->alloc_lock
);
1012 clear_tsk_thread_flag(p
, TIF_SIGPENDING
);
1013 init_sigpending(&p
->pending
);
1015 p
->utime
= cputime_zero
;
1016 p
->stime
= cputime_zero
;
1017 p
->gtime
= cputime_zero
;
1018 p
->utimescaled
= cputime_zero
;
1019 p
->stimescaled
= cputime_zero
;
1020 p
->prev_utime
= cputime_zero
;
1021 p
->prev_stime
= cputime_zero
;
1023 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1025 #ifdef CONFIG_DETECT_SOFTLOCKUP
1026 p
->last_switch_count
= 0;
1027 p
->last_switch_timestamp
= 0;
1030 task_io_accounting_init(&p
->ioac
);
1031 acct_clear_integrals(p
);
1033 posix_cpu_timers_init(p
);
1035 p
->lock_depth
= -1; /* -1 = no lock */
1036 do_posix_clock_monotonic_gettime(&p
->start_time
);
1037 p
->real_start_time
= p
->start_time
;
1038 monotonic_to_bootbased(&p
->real_start_time
);
1039 #ifdef CONFIG_SECURITY
1042 p
->cap_bset
= current
->cap_bset
;
1043 p
->io_context
= NULL
;
1044 p
->audit_context
= NULL
;
1047 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1048 if (IS_ERR(p
->mempolicy
)) {
1049 retval
= PTR_ERR(p
->mempolicy
);
1050 p
->mempolicy
= NULL
;
1051 goto bad_fork_cleanup_cgroup
;
1053 mpol_fix_fork_child_flag(p
);
1055 #ifdef CONFIG_TRACE_IRQFLAGS
1057 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1058 p
->hardirqs_enabled
= 1;
1060 p
->hardirqs_enabled
= 0;
1062 p
->hardirq_enable_ip
= 0;
1063 p
->hardirq_enable_event
= 0;
1064 p
->hardirq_disable_ip
= _THIS_IP_
;
1065 p
->hardirq_disable_event
= 0;
1066 p
->softirqs_enabled
= 1;
1067 p
->softirq_enable_ip
= _THIS_IP_
;
1068 p
->softirq_enable_event
= 0;
1069 p
->softirq_disable_ip
= 0;
1070 p
->softirq_disable_event
= 0;
1071 p
->hardirq_context
= 0;
1072 p
->softirq_context
= 0;
1074 #ifdef CONFIG_LOCKDEP
1075 p
->lockdep_depth
= 0; /* no locks held yet */
1076 p
->curr_chain_key
= 0;
1077 p
->lockdep_recursion
= 0;
1080 #ifdef CONFIG_DEBUG_MUTEXES
1081 p
->blocked_on
= NULL
; /* not blocked yet */
1084 /* Perform scheduler related setup. Assign this task to a CPU. */
1085 sched_fork(p
, clone_flags
);
1087 if ((retval
= security_task_alloc(p
)))
1088 goto bad_fork_cleanup_policy
;
1089 if ((retval
= audit_alloc(p
)))
1090 goto bad_fork_cleanup_security
;
1091 /* copy all the process information */
1092 if ((retval
= copy_semundo(clone_flags
, p
)))
1093 goto bad_fork_cleanup_audit
;
1094 if ((retval
= copy_files(clone_flags
, p
)))
1095 goto bad_fork_cleanup_semundo
;
1096 if ((retval
= copy_fs(clone_flags
, p
)))
1097 goto bad_fork_cleanup_files
;
1098 if ((retval
= copy_sighand(clone_flags
, p
)))
1099 goto bad_fork_cleanup_fs
;
1100 if ((retval
= copy_signal(clone_flags
, p
)))
1101 goto bad_fork_cleanup_sighand
;
1102 if ((retval
= copy_mm(clone_flags
, p
)))
1103 goto bad_fork_cleanup_signal
;
1104 if ((retval
= copy_keys(clone_flags
, p
)))
1105 goto bad_fork_cleanup_mm
;
1106 if ((retval
= copy_namespaces(clone_flags
, p
)))
1107 goto bad_fork_cleanup_keys
;
1108 if ((retval
= copy_io(clone_flags
, p
)))
1109 goto bad_fork_cleanup_namespaces
;
1110 retval
= copy_thread(0, clone_flags
, stack_start
, stack_size
, p
, regs
);
1112 goto bad_fork_cleanup_io
;
1114 if (pid
!= &init_struct_pid
) {
1116 pid
= alloc_pid(task_active_pid_ns(p
));
1118 goto bad_fork_cleanup_io
;
1120 if (clone_flags
& CLONE_NEWPID
) {
1121 retval
= pid_ns_prepare_proc(task_active_pid_ns(p
));
1123 goto bad_fork_free_pid
;
1127 p
->pid
= pid_nr(pid
);
1129 if (clone_flags
& CLONE_THREAD
)
1130 p
->tgid
= current
->tgid
;
1132 if (current
->nsproxy
!= p
->nsproxy
) {
1133 retval
= ns_cgroup_clone(p
, pid
);
1135 goto bad_fork_free_pid
;
1138 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1140 * Clear TID on mm_release()?
1142 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1144 p
->robust_list
= NULL
;
1145 #ifdef CONFIG_COMPAT
1146 p
->compat_robust_list
= NULL
;
1148 INIT_LIST_HEAD(&p
->pi_state_list
);
1149 p
->pi_state_cache
= NULL
;
1152 * sigaltstack should be cleared when sharing the same VM
1154 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1155 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1158 * Syscall tracing should be turned off in the child regardless
1161 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1162 #ifdef TIF_SYSCALL_EMU
1163 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1165 clear_all_latency_tracing(p
);
1167 /* Our parent execution domain becomes current domain
1168 These must match for thread signalling to apply */
1169 p
->parent_exec_id
= p
->self_exec_id
;
1171 /* ok, now we should be set up.. */
1172 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1173 p
->pdeath_signal
= 0;
1177 * Ok, make it visible to the rest of the system.
1178 * We dont wake it up yet.
1180 p
->group_leader
= p
;
1181 INIT_LIST_HEAD(&p
->thread_group
);
1183 /* Now that the task is set up, run cgroup callbacks if
1184 * necessary. We need to run them before the task is visible
1185 * on the tasklist. */
1186 cgroup_fork_callbacks(p
);
1187 cgroup_callbacks_done
= 1;
1189 /* Need tasklist lock for parent etc handling! */
1190 write_lock_irq(&tasklist_lock
);
1193 * The task hasn't been attached yet, so its cpus_allowed mask will
1194 * not be changed, nor will its assigned CPU.
1196 * The cpus_allowed mask of the parent may have changed after it was
1197 * copied first time - so re-copy it here, then check the child's CPU
1198 * to ensure it is on a valid CPU (and if not, just force it back to
1199 * parent's CPU). This avoids alot of nasty races.
1201 p
->cpus_allowed
= current
->cpus_allowed
;
1202 p
->rt
.nr_cpus_allowed
= current
->rt
.nr_cpus_allowed
;
1203 if (unlikely(!cpu_isset(task_cpu(p
), p
->cpus_allowed
) ||
1204 !cpu_online(task_cpu(p
))))
1205 set_task_cpu(p
, smp_processor_id());
1207 /* CLONE_PARENT re-uses the old parent */
1208 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
))
1209 p
->real_parent
= current
->real_parent
;
1211 p
->real_parent
= current
;
1213 spin_lock(¤t
->sighand
->siglock
);
1216 * Process group and session signals need to be delivered to just the
1217 * parent before the fork or both the parent and the child after the
1218 * fork. Restart if a signal comes in before we add the new process to
1219 * it's process group.
1220 * A fatal signal pending means that current will exit, so the new
1221 * thread can't slip out of an OOM kill (or normal SIGKILL).
1223 recalc_sigpending();
1224 if (signal_pending(current
)) {
1225 spin_unlock(¤t
->sighand
->siglock
);
1226 write_unlock_irq(&tasklist_lock
);
1227 retval
= -ERESTARTNOINTR
;
1228 goto bad_fork_free_pid
;
1231 if (clone_flags
& CLONE_THREAD
) {
1232 p
->group_leader
= current
->group_leader
;
1233 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1236 if (likely(p
->pid
)) {
1237 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1238 tracehook_finish_clone(p
, clone_flags
, trace
);
1240 if (thread_group_leader(p
)) {
1241 if (clone_flags
& CLONE_NEWPID
)
1242 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1244 p
->signal
->leader_pid
= pid
;
1245 tty_kref_put(p
->signal
->tty
);
1246 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1247 set_task_pgrp(p
, task_pgrp_nr(current
));
1248 set_task_session(p
, task_session_nr(current
));
1249 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1250 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1251 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1252 __get_cpu_var(process_counts
)++;
1254 attach_pid(p
, PIDTYPE_PID
, pid
);
1259 spin_unlock(¤t
->sighand
->siglock
);
1260 write_unlock_irq(&tasklist_lock
);
1261 proc_fork_connector(p
);
1262 cgroup_post_fork(p
);
1266 if (pid
!= &init_struct_pid
)
1268 bad_fork_cleanup_io
:
1269 put_io_context(p
->io_context
);
1270 bad_fork_cleanup_namespaces
:
1271 exit_task_namespaces(p
);
1272 bad_fork_cleanup_keys
:
1274 bad_fork_cleanup_mm
:
1277 bad_fork_cleanup_signal
:
1279 bad_fork_cleanup_sighand
:
1280 __cleanup_sighand(p
->sighand
);
1281 bad_fork_cleanup_fs
:
1282 exit_fs(p
); /* blocking */
1283 bad_fork_cleanup_files
:
1284 exit_files(p
); /* blocking */
1285 bad_fork_cleanup_semundo
:
1287 bad_fork_cleanup_audit
:
1289 bad_fork_cleanup_security
:
1290 security_task_free(p
);
1291 bad_fork_cleanup_policy
:
1293 mpol_put(p
->mempolicy
);
1294 bad_fork_cleanup_cgroup
:
1296 cgroup_exit(p
, cgroup_callbacks_done
);
1297 delayacct_tsk_free(p
);
1299 module_put(p
->binfmt
->module
);
1300 bad_fork_cleanup_put_domain
:
1301 module_put(task_thread_info(p
)->exec_domain
->module
);
1302 bad_fork_cleanup_count
:
1303 put_group_info(p
->group_info
);
1304 atomic_dec(&p
->user
->processes
);
1309 return ERR_PTR(retval
);
1312 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1314 memset(regs
, 0, sizeof(struct pt_regs
));
1318 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1320 struct task_struct
*task
;
1321 struct pt_regs regs
;
1323 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1324 &init_struct_pid
, 0);
1326 init_idle(task
, cpu
);
1332 * Ok, this is the main fork-routine.
1334 * It copies the process, and if successful kick-starts
1335 * it and waits for it to finish using the VM if required.
1337 long do_fork(unsigned long clone_flags
,
1338 unsigned long stack_start
,
1339 struct pt_regs
*regs
,
1340 unsigned long stack_size
,
1341 int __user
*parent_tidptr
,
1342 int __user
*child_tidptr
)
1344 struct task_struct
*p
;
1349 * We hope to recycle these flags after 2.6.26
1351 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1352 static int __read_mostly count
= 100;
1354 if (count
> 0 && printk_ratelimit()) {
1355 char comm
[TASK_COMM_LEN
];
1358 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1359 "clone flags 0x%lx\n",
1360 get_task_comm(comm
, current
),
1361 clone_flags
& CLONE_STOPPED
);
1366 * When called from kernel_thread, don't do user tracing stuff.
1368 if (likely(user_mode(regs
)))
1369 trace
= tracehook_prepare_clone(clone_flags
);
1371 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1372 child_tidptr
, NULL
, trace
);
1374 * Do this prior waking up the new thread - the thread pointer
1375 * might get invalid after that point, if the thread exits quickly.
1378 struct completion vfork
;
1380 trace_sched_process_fork(current
, p
);
1382 nr
= task_pid_vnr(p
);
1384 if (clone_flags
& CLONE_PARENT_SETTID
)
1385 put_user(nr
, parent_tidptr
);
1387 if (clone_flags
& CLONE_VFORK
) {
1388 p
->vfork_done
= &vfork
;
1389 init_completion(&vfork
);
1392 tracehook_report_clone(trace
, regs
, clone_flags
, nr
, p
);
1395 * We set PF_STARTING at creation in case tracing wants to
1396 * use this to distinguish a fully live task from one that
1397 * hasn't gotten to tracehook_report_clone() yet. Now we
1398 * clear it and set the child going.
1400 p
->flags
&= ~PF_STARTING
;
1402 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1404 * We'll start up with an immediate SIGSTOP.
1406 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1407 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1408 __set_task_state(p
, TASK_STOPPED
);
1410 wake_up_new_task(p
, clone_flags
);
1413 tracehook_report_clone_complete(trace
, regs
,
1414 clone_flags
, nr
, p
);
1416 if (clone_flags
& CLONE_VFORK
) {
1417 freezer_do_not_count();
1418 wait_for_completion(&vfork
);
1420 tracehook_report_vfork_done(p
, nr
);
1428 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1429 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1432 static void sighand_ctor(void *data
)
1434 struct sighand_struct
*sighand
= data
;
1436 spin_lock_init(&sighand
->siglock
);
1437 init_waitqueue_head(&sighand
->signalfd_wqh
);
1440 void __init
proc_caches_init(void)
1442 sighand_cachep
= kmem_cache_create("sighand_cache",
1443 sizeof(struct sighand_struct
), 0,
1444 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
,
1446 signal_cachep
= kmem_cache_create("signal_cache",
1447 sizeof(struct signal_struct
), 0,
1448 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1449 files_cachep
= kmem_cache_create("files_cache",
1450 sizeof(struct files_struct
), 0,
1451 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1452 fs_cachep
= kmem_cache_create("fs_cache",
1453 sizeof(struct fs_struct
), 0,
1454 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1455 vm_area_cachep
= kmem_cache_create("vm_area_struct",
1456 sizeof(struct vm_area_struct
), 0,
1458 mm_cachep
= kmem_cache_create("mm_struct",
1459 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1460 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
);
1464 * Check constraints on flags passed to the unshare system call and
1465 * force unsharing of additional process context as appropriate.
1467 static void check_unshare_flags(unsigned long *flags_ptr
)
1470 * If unsharing a thread from a thread group, must also
1473 if (*flags_ptr
& CLONE_THREAD
)
1474 *flags_ptr
|= CLONE_VM
;
1477 * If unsharing vm, must also unshare signal handlers.
1479 if (*flags_ptr
& CLONE_VM
)
1480 *flags_ptr
|= CLONE_SIGHAND
;
1483 * If unsharing signal handlers and the task was created
1484 * using CLONE_THREAD, then must unshare the thread
1486 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1487 (atomic_read(¤t
->signal
->count
) > 1))
1488 *flags_ptr
|= CLONE_THREAD
;
1491 * If unsharing namespace, must also unshare filesystem information.
1493 if (*flags_ptr
& CLONE_NEWNS
)
1494 *flags_ptr
|= CLONE_FS
;
1498 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1500 static int unshare_thread(unsigned long unshare_flags
)
1502 if (unshare_flags
& CLONE_THREAD
)
1509 * Unshare the filesystem structure if it is being shared
1511 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1513 struct fs_struct
*fs
= current
->fs
;
1515 if ((unshare_flags
& CLONE_FS
) &&
1516 (fs
&& atomic_read(&fs
->count
) > 1)) {
1517 *new_fsp
= __copy_fs_struct(current
->fs
);
1526 * Unsharing of sighand is not supported yet
1528 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1530 struct sighand_struct
*sigh
= current
->sighand
;
1532 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1539 * Unshare vm if it is being shared
1541 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1543 struct mm_struct
*mm
= current
->mm
;
1545 if ((unshare_flags
& CLONE_VM
) &&
1546 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1554 * Unshare file descriptor table if it is being shared
1556 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1558 struct files_struct
*fd
= current
->files
;
1561 if ((unshare_flags
& CLONE_FILES
) &&
1562 (fd
&& atomic_read(&fd
->count
) > 1)) {
1563 *new_fdp
= dup_fd(fd
, &error
);
1572 * unshare allows a process to 'unshare' part of the process
1573 * context which was originally shared using clone. copy_*
1574 * functions used by do_fork() cannot be used here directly
1575 * because they modify an inactive task_struct that is being
1576 * constructed. Here we are modifying the current, active,
1579 asmlinkage
long sys_unshare(unsigned long unshare_flags
)
1582 struct fs_struct
*fs
, *new_fs
= NULL
;
1583 struct sighand_struct
*new_sigh
= NULL
;
1584 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1585 struct files_struct
*fd
, *new_fd
= NULL
;
1586 struct nsproxy
*new_nsproxy
= NULL
;
1589 check_unshare_flags(&unshare_flags
);
1591 /* Return -EINVAL for all unsupported flags */
1593 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1594 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1595 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWUSER
|
1597 goto bad_unshare_out
;
1600 * CLONE_NEWIPC must also detach from the undolist: after switching
1601 * to a new ipc namespace, the semaphore arrays from the old
1602 * namespace are unreachable.
1604 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1606 if ((err
= unshare_thread(unshare_flags
)))
1607 goto bad_unshare_out
;
1608 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1609 goto bad_unshare_cleanup_thread
;
1610 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1611 goto bad_unshare_cleanup_fs
;
1612 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1613 goto bad_unshare_cleanup_sigh
;
1614 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1615 goto bad_unshare_cleanup_vm
;
1616 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1618 goto bad_unshare_cleanup_fd
;
1620 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1623 * CLONE_SYSVSEM is equivalent to sys_exit().
1629 switch_task_namespaces(current
, new_nsproxy
);
1637 current
->fs
= new_fs
;
1643 active_mm
= current
->active_mm
;
1644 current
->mm
= new_mm
;
1645 current
->active_mm
= new_mm
;
1646 activate_mm(active_mm
, new_mm
);
1651 fd
= current
->files
;
1652 current
->files
= new_fd
;
1656 task_unlock(current
);
1660 put_nsproxy(new_nsproxy
);
1662 bad_unshare_cleanup_fd
:
1664 put_files_struct(new_fd
);
1666 bad_unshare_cleanup_vm
:
1670 bad_unshare_cleanup_sigh
:
1672 if (atomic_dec_and_test(&new_sigh
->count
))
1673 kmem_cache_free(sighand_cachep
, new_sigh
);
1675 bad_unshare_cleanup_fs
:
1677 put_fs_struct(new_fs
);
1679 bad_unshare_cleanup_thread
:
1685 * Helper to unshare the files of the current task.
1686 * We don't want to expose copy_files internals to
1687 * the exec layer of the kernel.
1690 int unshare_files(struct files_struct
**displaced
)
1692 struct task_struct
*task
= current
;
1693 struct files_struct
*copy
= NULL
;
1696 error
= unshare_fd(CLONE_FILES
, ©
);
1697 if (error
|| !copy
) {
1701 *displaced
= task
->files
;