4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
14 #include <linux/slab.h>
15 #include <linux/init.h>
16 #include <linux/unistd.h>
17 #include <linux/module.h>
18 #include <linux/vmalloc.h>
19 #include <linux/completion.h>
20 #include <linux/personality.h>
21 #include <linux/mempolicy.h>
22 #include <linux/sem.h>
23 #include <linux/file.h>
24 #include <linux/fdtable.h>
25 #include <linux/iocontext.h>
26 #include <linux/key.h>
27 #include <linux/binfmts.h>
28 #include <linux/mman.h>
29 #include <linux/mmu_notifier.h>
31 #include <linux/nsproxy.h>
32 #include <linux/capability.h>
33 #include <linux/cpu.h>
34 #include <linux/cgroup.h>
35 #include <linux/security.h>
36 #include <linux/hugetlb.h>
37 #include <linux/swap.h>
38 #include <linux/syscalls.h>
39 #include <linux/jiffies.h>
40 #include <linux/tracehook.h>
41 #include <linux/futex.h>
42 #include <linux/compat.h>
43 #include <linux/task_io_accounting_ops.h>
44 #include <linux/rcupdate.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/audit.h>
48 #include <linux/memcontrol.h>
49 #include <linux/ftrace.h>
50 #include <linux/profile.h>
51 #include <linux/rmap.h>
52 #include <linux/ksm.h>
53 #include <linux/acct.h>
54 #include <linux/tsacct_kern.h>
55 #include <linux/cn_proc.h>
56 #include <linux/freezer.h>
57 #include <linux/delayacct.h>
58 #include <linux/taskstats_kern.h>
59 #include <linux/random.h>
60 #include <linux/tty.h>
61 #include <linux/proc_fs.h>
62 #include <linux/blkdev.h>
63 #include <linux/fs_struct.h>
64 #include <linux/magic.h>
65 #include <linux/perf_event.h>
66 #include <linux/posix-timers.h>
67 #include <linux/user-return-notifier.h>
68 #include <linux/oom.h>
70 #include <asm/pgtable.h>
71 #include <asm/pgalloc.h>
72 #include <asm/uaccess.h>
73 #include <asm/mmu_context.h>
74 #include <asm/cacheflush.h>
75 #include <asm/tlbflush.h>
77 #include <trace/events/sched.h>
80 * Protected counters by write_lock_irq(&tasklist_lock)
82 unsigned long total_forks
; /* Handle normal Linux uptimes. */
83 int nr_threads
; /* The idle threads do not count.. */
85 int max_threads
; /* tunable limit on nr_threads */
87 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
89 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
91 #ifdef CONFIG_PROVE_RCU
92 int lockdep_tasklist_lock_is_held(void)
94 return lockdep_is_held(&tasklist_lock
);
96 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
97 #endif /* #ifdef CONFIG_PROVE_RCU */
99 int nr_processes(void)
104 for_each_possible_cpu(cpu
)
105 total
+= per_cpu(process_counts
, cpu
);
110 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
111 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
112 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
113 static struct kmem_cache
*task_struct_cachep
;
116 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
117 static inline struct thread_info
*alloc_thread_info(struct task_struct
*tsk
)
119 #ifdef CONFIG_DEBUG_STACK_USAGE
120 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
122 gfp_t mask
= GFP_KERNEL
;
124 return (struct thread_info
*)__get_free_pages(mask
, THREAD_SIZE_ORDER
);
127 static inline void free_thread_info(struct thread_info
*ti
)
129 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
133 /* SLAB cache for signal_struct structures (tsk->signal) */
134 static struct kmem_cache
*signal_cachep
;
136 /* SLAB cache for sighand_struct structures (tsk->sighand) */
137 struct kmem_cache
*sighand_cachep
;
139 /* SLAB cache for files_struct structures (tsk->files) */
140 struct kmem_cache
*files_cachep
;
142 /* SLAB cache for fs_struct structures (tsk->fs) */
143 struct kmem_cache
*fs_cachep
;
145 /* SLAB cache for vm_area_struct structures */
146 struct kmem_cache
*vm_area_cachep
;
148 /* SLAB cache for mm_struct structures (tsk->mm) */
149 static struct kmem_cache
*mm_cachep
;
151 static void account_kernel_stack(struct thread_info
*ti
, int account
)
153 struct zone
*zone
= page_zone(virt_to_page(ti
));
155 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
158 void free_task(struct task_struct
*tsk
)
160 prop_local_destroy_single(&tsk
->dirties
);
161 account_kernel_stack(tsk
->stack
, -1);
162 free_thread_info(tsk
->stack
);
163 rt_mutex_debug_task_free(tsk
);
164 ftrace_graph_exit_task(tsk
);
165 free_task_struct(tsk
);
167 EXPORT_SYMBOL(free_task
);
169 static inline void free_signal_struct(struct signal_struct
*sig
)
171 taskstats_tgid_free(sig
);
172 kmem_cache_free(signal_cachep
, sig
);
175 static inline void put_signal_struct(struct signal_struct
*sig
)
177 if (atomic_dec_and_test(&sig
->sigcnt
)) {
178 sched_autogroup_exit(sig
);
179 free_signal_struct(sig
);
183 void __put_task_struct(struct task_struct
*tsk
)
185 WARN_ON(!tsk
->exit_state
);
186 WARN_ON(atomic_read(&tsk
->usage
));
187 WARN_ON(tsk
== current
);
190 delayacct_tsk_free(tsk
);
191 put_signal_struct(tsk
->signal
);
193 if (!profile_handoff_task(tsk
))
198 * macro override instead of weak attribute alias, to workaround
199 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
201 #ifndef arch_task_cache_init
202 #define arch_task_cache_init()
205 void __init
fork_init(unsigned long mempages
)
207 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
208 #ifndef ARCH_MIN_TASKALIGN
209 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
211 /* create a slab on which task_structs can be allocated */
213 kmem_cache_create("task_struct", sizeof(struct task_struct
),
214 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
217 /* do the arch specific task caches init */
218 arch_task_cache_init();
221 * The default maximum number of threads is set to a safe
222 * value: the thread structures can take up at most half
225 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
228 * we need to allow at least 20 threads to boot a system
233 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
234 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
235 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
236 init_task
.signal
->rlim
[RLIMIT_NPROC
];
239 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
240 struct task_struct
*src
)
246 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
248 struct task_struct
*tsk
;
249 struct thread_info
*ti
;
250 unsigned long *stackend
;
254 prepare_to_copy(orig
);
256 tsk
= alloc_task_struct();
260 ti
= alloc_thread_info(tsk
);
262 free_task_struct(tsk
);
266 err
= arch_dup_task_struct(tsk
, orig
);
272 err
= prop_local_init_single(&tsk
->dirties
);
276 setup_thread_stack(tsk
, orig
);
277 clear_user_return_notifier(tsk
);
278 clear_tsk_need_resched(tsk
);
279 stackend
= end_of_stack(tsk
);
280 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
282 #ifdef CONFIG_CC_STACKPROTECTOR
283 tsk
->stack_canary
= get_random_int();
286 /* One for us, one for whoever does the "release_task()" (usually parent) */
287 atomic_set(&tsk
->usage
,2);
288 atomic_set(&tsk
->fs_excl
, 0);
289 #ifdef CONFIG_BLK_DEV_IO_TRACE
292 tsk
->splice_pipe
= NULL
;
294 account_kernel_stack(ti
, 1);
299 free_thread_info(ti
);
300 free_task_struct(tsk
);
305 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
307 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
308 struct rb_node
**rb_link
, *rb_parent
;
310 unsigned long charge
;
311 struct mempolicy
*pol
;
313 down_write(&oldmm
->mmap_sem
);
314 flush_cache_dup_mm(oldmm
);
316 * Not linked in yet - no deadlock potential:
318 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
322 mm
->mmap_cache
= NULL
;
323 mm
->free_area_cache
= oldmm
->mmap_base
;
324 mm
->cached_hole_size
= ~0UL;
326 cpumask_clear(mm_cpumask(mm
));
328 rb_link
= &mm
->mm_rb
.rb_node
;
331 retval
= ksm_fork(mm
, oldmm
);
336 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
339 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
340 long pages
= vma_pages(mpnt
);
341 mm
->total_vm
-= pages
;
342 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
347 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
348 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
349 if (security_vm_enough_memory(len
))
353 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
357 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
358 pol
= mpol_dup(vma_policy(mpnt
));
359 retval
= PTR_ERR(pol
);
361 goto fail_nomem_policy
;
362 vma_set_policy(tmp
, pol
);
364 if (anon_vma_fork(tmp
, mpnt
))
365 goto fail_nomem_anon_vma_fork
;
366 tmp
->vm_flags
&= ~VM_LOCKED
;
367 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
370 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
371 struct address_space
*mapping
= file
->f_mapping
;
374 if (tmp
->vm_flags
& VM_DENYWRITE
)
375 atomic_dec(&inode
->i_writecount
);
376 spin_lock(&mapping
->i_mmap_lock
);
377 if (tmp
->vm_flags
& VM_SHARED
)
378 mapping
->i_mmap_writable
++;
379 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
380 flush_dcache_mmap_lock(mapping
);
381 /* insert tmp into the share list, just after mpnt */
382 vma_prio_tree_add(tmp
, mpnt
);
383 flush_dcache_mmap_unlock(mapping
);
384 spin_unlock(&mapping
->i_mmap_lock
);
388 * Clear hugetlb-related page reserves for children. This only
389 * affects MAP_PRIVATE mappings. Faults generated by the child
390 * are not guaranteed to succeed, even if read-only
392 if (is_vm_hugetlb_page(tmp
))
393 reset_vma_resv_huge_pages(tmp
);
396 * Link in the new vma and copy the page table entries.
399 pprev
= &tmp
->vm_next
;
403 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
404 rb_link
= &tmp
->vm_rb
.rb_right
;
405 rb_parent
= &tmp
->vm_rb
;
408 retval
= copy_page_range(mm
, oldmm
, mpnt
);
410 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
411 tmp
->vm_ops
->open(tmp
);
416 /* a new mm has just been created */
417 arch_dup_mmap(oldmm
, mm
);
420 up_write(&mm
->mmap_sem
);
422 up_write(&oldmm
->mmap_sem
);
424 fail_nomem_anon_vma_fork
:
427 kmem_cache_free(vm_area_cachep
, tmp
);
430 vm_unacct_memory(charge
);
434 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
436 mm
->pgd
= pgd_alloc(mm
);
437 if (unlikely(!mm
->pgd
))
442 static inline void mm_free_pgd(struct mm_struct
* mm
)
444 pgd_free(mm
, mm
->pgd
);
447 #define dup_mmap(mm, oldmm) (0)
448 #define mm_alloc_pgd(mm) (0)
449 #define mm_free_pgd(mm)
450 #endif /* CONFIG_MMU */
452 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
454 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
455 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
457 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
459 static int __init
coredump_filter_setup(char *s
)
461 default_dump_filter
=
462 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
463 MMF_DUMP_FILTER_MASK
;
467 __setup("coredump_filter=", coredump_filter_setup
);
469 #include <linux/init_task.h>
471 static void mm_init_aio(struct mm_struct
*mm
)
474 spin_lock_init(&mm
->ioctx_lock
);
475 INIT_HLIST_HEAD(&mm
->ioctx_list
);
479 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
481 atomic_set(&mm
->mm_users
, 1);
482 atomic_set(&mm
->mm_count
, 1);
483 init_rwsem(&mm
->mmap_sem
);
484 INIT_LIST_HEAD(&mm
->mmlist
);
485 mm
->flags
= (current
->mm
) ?
486 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
487 mm
->core_state
= NULL
;
489 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
490 spin_lock_init(&mm
->page_table_lock
);
491 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
492 mm
->cached_hole_size
= ~0UL;
494 mm_init_owner(mm
, p
);
495 atomic_set(&mm
->oom_disable_count
, 0);
497 if (likely(!mm_alloc_pgd(mm
))) {
499 mmu_notifier_mm_init(mm
);
508 * Allocate and initialize an mm_struct.
510 struct mm_struct
* mm_alloc(void)
512 struct mm_struct
* mm
;
516 memset(mm
, 0, sizeof(*mm
));
517 mm
= mm_init(mm
, current
);
523 * Called when the last reference to the mm
524 * is dropped: either by a lazy thread or by
525 * mmput. Free the page directory and the mm.
527 void __mmdrop(struct mm_struct
*mm
)
529 BUG_ON(mm
== &init_mm
);
532 mmu_notifier_mm_destroy(mm
);
535 EXPORT_SYMBOL_GPL(__mmdrop
);
538 * Decrement the use count and release all resources for an mm.
540 void mmput(struct mm_struct
*mm
)
544 if (atomic_dec_and_test(&mm
->mm_users
)) {
548 set_mm_exe_file(mm
, NULL
);
549 if (!list_empty(&mm
->mmlist
)) {
550 spin_lock(&mmlist_lock
);
551 list_del(&mm
->mmlist
);
552 spin_unlock(&mmlist_lock
);
556 module_put(mm
->binfmt
->module
);
560 EXPORT_SYMBOL_GPL(mmput
);
563 * get_task_mm - acquire a reference to the task's mm
565 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
566 * this kernel workthread has transiently adopted a user mm with use_mm,
567 * to do its AIO) is not set and if so returns a reference to it, after
568 * bumping up the use count. User must release the mm via mmput()
569 * after use. Typically used by /proc and ptrace.
571 struct mm_struct
*get_task_mm(struct task_struct
*task
)
573 struct mm_struct
*mm
;
578 if (task
->flags
& PF_KTHREAD
)
581 atomic_inc(&mm
->mm_users
);
586 EXPORT_SYMBOL_GPL(get_task_mm
);
588 /* Please note the differences between mmput and mm_release.
589 * mmput is called whenever we stop holding onto a mm_struct,
590 * error success whatever.
592 * mm_release is called after a mm_struct has been removed
593 * from the current process.
595 * This difference is important for error handling, when we
596 * only half set up a mm_struct for a new process and need to restore
597 * the old one. Because we mmput the new mm_struct before
598 * restoring the old one. . .
599 * Eric Biederman 10 January 1998
601 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
603 struct completion
*vfork_done
= tsk
->vfork_done
;
605 /* Get rid of any futexes when releasing the mm */
607 if (unlikely(tsk
->robust_list
)) {
608 exit_robust_list(tsk
);
609 tsk
->robust_list
= NULL
;
612 if (unlikely(tsk
->compat_robust_list
)) {
613 compat_exit_robust_list(tsk
);
614 tsk
->compat_robust_list
= NULL
;
617 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
618 exit_pi_state_list(tsk
);
621 /* Get rid of any cached register state */
622 deactivate_mm(tsk
, mm
);
624 /* notify parent sleeping on vfork() */
626 tsk
->vfork_done
= NULL
;
627 complete(vfork_done
);
631 * If we're exiting normally, clear a user-space tid field if
632 * requested. We leave this alone when dying by signal, to leave
633 * the value intact in a core dump, and to save the unnecessary
634 * trouble otherwise. Userland only wants this done for a sys_exit.
636 if (tsk
->clear_child_tid
) {
637 if (!(tsk
->flags
& PF_SIGNALED
) &&
638 atomic_read(&mm
->mm_users
) > 1) {
640 * We don't check the error code - if userspace has
641 * not set up a proper pointer then tough luck.
643 put_user(0, tsk
->clear_child_tid
);
644 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
647 tsk
->clear_child_tid
= NULL
;
652 * Allocate a new mm structure and copy contents from the
653 * mm structure of the passed in task structure.
655 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
657 struct mm_struct
*mm
, *oldmm
= current
->mm
;
667 memcpy(mm
, oldmm
, sizeof(*mm
));
669 /* Initializing for Swap token stuff */
670 mm
->token_priority
= 0;
671 mm
->last_interval
= 0;
673 if (!mm_init(mm
, tsk
))
676 if (init_new_context(tsk
, mm
))
679 dup_mm_exe_file(oldmm
, mm
);
681 err
= dup_mmap(mm
, oldmm
);
685 mm
->hiwater_rss
= get_mm_rss(mm
);
686 mm
->hiwater_vm
= mm
->total_vm
;
688 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
694 /* don't put binfmt in mmput, we haven't got module yet */
703 * If init_new_context() failed, we cannot use mmput() to free the mm
704 * because it calls destroy_context()
711 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
713 struct mm_struct
* mm
, *oldmm
;
716 tsk
->min_flt
= tsk
->maj_flt
= 0;
717 tsk
->nvcsw
= tsk
->nivcsw
= 0;
718 #ifdef CONFIG_DETECT_HUNG_TASK
719 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
723 tsk
->active_mm
= NULL
;
726 * Are we cloning a kernel thread?
728 * We need to steal a active VM for that..
734 if (clone_flags
& CLONE_VM
) {
735 atomic_inc(&oldmm
->mm_users
);
746 /* Initializing for Swap token stuff */
747 mm
->token_priority
= 0;
748 mm
->last_interval
= 0;
749 if (tsk
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
)
750 atomic_inc(&mm
->oom_disable_count
);
760 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
762 struct fs_struct
*fs
= current
->fs
;
763 if (clone_flags
& CLONE_FS
) {
764 /* tsk->fs is already what we want */
765 spin_lock(&fs
->lock
);
767 spin_unlock(&fs
->lock
);
771 spin_unlock(&fs
->lock
);
774 tsk
->fs
= copy_fs_struct(fs
);
780 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
782 struct files_struct
*oldf
, *newf
;
786 * A background process may not have any files ...
788 oldf
= current
->files
;
792 if (clone_flags
& CLONE_FILES
) {
793 atomic_inc(&oldf
->count
);
797 newf
= dup_fd(oldf
, &error
);
807 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
810 struct io_context
*ioc
= current
->io_context
;
815 * Share io context with parent, if CLONE_IO is set
817 if (clone_flags
& CLONE_IO
) {
818 tsk
->io_context
= ioc_task_link(ioc
);
819 if (unlikely(!tsk
->io_context
))
821 } else if (ioprio_valid(ioc
->ioprio
)) {
822 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
823 if (unlikely(!tsk
->io_context
))
826 tsk
->io_context
->ioprio
= ioc
->ioprio
;
832 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
834 struct sighand_struct
*sig
;
836 if (clone_flags
& CLONE_SIGHAND
) {
837 atomic_inc(¤t
->sighand
->count
);
840 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
841 rcu_assign_pointer(tsk
->sighand
, sig
);
844 atomic_set(&sig
->count
, 1);
845 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
849 void __cleanup_sighand(struct sighand_struct
*sighand
)
851 if (atomic_dec_and_test(&sighand
->count
))
852 kmem_cache_free(sighand_cachep
, sighand
);
857 * Initialize POSIX timer handling for a thread group.
859 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
861 unsigned long cpu_limit
;
863 /* Thread group counters. */
864 thread_group_cputime_init(sig
);
866 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
867 if (cpu_limit
!= RLIM_INFINITY
) {
868 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
869 sig
->cputimer
.running
= 1;
872 /* The timer lists. */
873 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
874 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
875 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
878 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
880 struct signal_struct
*sig
;
882 if (clone_flags
& CLONE_THREAD
)
885 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
891 atomic_set(&sig
->live
, 1);
892 atomic_set(&sig
->sigcnt
, 1);
893 init_waitqueue_head(&sig
->wait_chldexit
);
894 if (clone_flags
& CLONE_NEWPID
)
895 sig
->flags
|= SIGNAL_UNKILLABLE
;
896 sig
->curr_target
= tsk
;
897 init_sigpending(&sig
->shared_pending
);
898 INIT_LIST_HEAD(&sig
->posix_timers
);
900 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
901 sig
->real_timer
.function
= it_real_fn
;
903 task_lock(current
->group_leader
);
904 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
905 task_unlock(current
->group_leader
);
907 posix_cpu_timers_init_group(sig
);
910 sched_autogroup_fork(sig
);
912 sig
->oom_adj
= current
->signal
->oom_adj
;
913 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
915 mutex_init(&sig
->cred_guard_mutex
);
920 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
922 unsigned long new_flags
= p
->flags
;
924 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
925 new_flags
|= PF_FORKNOEXEC
;
926 new_flags
|= PF_STARTING
;
927 p
->flags
= new_flags
;
928 clear_freeze_flag(p
);
931 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
933 current
->clear_child_tid
= tidptr
;
935 return task_pid_vnr(current
);
938 static void rt_mutex_init_task(struct task_struct
*p
)
940 raw_spin_lock_init(&p
->pi_lock
);
941 #ifdef CONFIG_RT_MUTEXES
942 plist_head_init_raw(&p
->pi_waiters
, &p
->pi_lock
);
943 p
->pi_blocked_on
= NULL
;
947 #ifdef CONFIG_MM_OWNER
948 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
952 #endif /* CONFIG_MM_OWNER */
955 * Initialize POSIX timer handling for a single task.
957 static void posix_cpu_timers_init(struct task_struct
*tsk
)
959 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
960 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
961 tsk
->cputime_expires
.sched_exp
= 0;
962 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
963 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
964 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
968 * This creates a new process as a copy of the old one,
969 * but does not actually start it yet.
971 * It copies the registers, and all the appropriate
972 * parts of the process environment (as per the clone
973 * flags). The actual kick-off is left to the caller.
975 static struct task_struct
*copy_process(unsigned long clone_flags
,
976 unsigned long stack_start
,
977 struct pt_regs
*regs
,
978 unsigned long stack_size
,
979 int __user
*child_tidptr
,
984 struct task_struct
*p
;
985 int cgroup_callbacks_done
= 0;
987 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
988 return ERR_PTR(-EINVAL
);
991 * Thread groups must share signals as well, and detached threads
992 * can only be started up within the thread group.
994 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
995 return ERR_PTR(-EINVAL
);
998 * Shared signal handlers imply shared VM. By way of the above,
999 * thread groups also imply shared VM. Blocking this case allows
1000 * for various simplifications in other code.
1002 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1003 return ERR_PTR(-EINVAL
);
1006 * Siblings of global init remain as zombies on exit since they are
1007 * not reaped by their parent (swapper). To solve this and to avoid
1008 * multi-rooted process trees, prevent global and container-inits
1009 * from creating siblings.
1011 if ((clone_flags
& CLONE_PARENT
) &&
1012 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1013 return ERR_PTR(-EINVAL
);
1015 retval
= security_task_create(clone_flags
);
1020 p
= dup_task_struct(current
);
1024 ftrace_graph_init_task(p
);
1026 rt_mutex_init_task(p
);
1028 #ifdef CONFIG_PROVE_LOCKING
1029 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1030 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1033 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1034 task_rlimit(p
, RLIMIT_NPROC
)) {
1035 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1036 p
->real_cred
->user
!= INIT_USER
)
1040 retval
= copy_creds(p
, clone_flags
);
1045 * If multiple threads are within copy_process(), then this check
1046 * triggers too late. This doesn't hurt, the check is only there
1047 * to stop root fork bombs.
1050 if (nr_threads
>= max_threads
)
1051 goto bad_fork_cleanup_count
;
1053 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1054 goto bad_fork_cleanup_count
;
1057 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1058 copy_flags(clone_flags
, p
);
1059 INIT_LIST_HEAD(&p
->children
);
1060 INIT_LIST_HEAD(&p
->sibling
);
1061 rcu_copy_process(p
);
1062 p
->vfork_done
= NULL
;
1063 spin_lock_init(&p
->alloc_lock
);
1065 init_sigpending(&p
->pending
);
1067 p
->utime
= cputime_zero
;
1068 p
->stime
= cputime_zero
;
1069 p
->gtime
= cputime_zero
;
1070 p
->utimescaled
= cputime_zero
;
1071 p
->stimescaled
= cputime_zero
;
1072 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1073 p
->prev_utime
= cputime_zero
;
1074 p
->prev_stime
= cputime_zero
;
1076 #if defined(SPLIT_RSS_COUNTING)
1077 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1080 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1082 task_io_accounting_init(&p
->ioac
);
1083 acct_clear_integrals(p
);
1085 posix_cpu_timers_init(p
);
1087 p
->lock_depth
= -1; /* -1 = no lock */
1088 do_posix_clock_monotonic_gettime(&p
->start_time
);
1089 p
->real_start_time
= p
->start_time
;
1090 monotonic_to_bootbased(&p
->real_start_time
);
1091 p
->io_context
= NULL
;
1092 p
->audit_context
= NULL
;
1095 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1096 if (IS_ERR(p
->mempolicy
)) {
1097 retval
= PTR_ERR(p
->mempolicy
);
1098 p
->mempolicy
= NULL
;
1099 goto bad_fork_cleanup_cgroup
;
1101 mpol_fix_fork_child_flag(p
);
1103 #ifdef CONFIG_TRACE_IRQFLAGS
1105 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1106 p
->hardirqs_enabled
= 1;
1108 p
->hardirqs_enabled
= 0;
1110 p
->hardirq_enable_ip
= 0;
1111 p
->hardirq_enable_event
= 0;
1112 p
->hardirq_disable_ip
= _THIS_IP_
;
1113 p
->hardirq_disable_event
= 0;
1114 p
->softirqs_enabled
= 1;
1115 p
->softirq_enable_ip
= _THIS_IP_
;
1116 p
->softirq_enable_event
= 0;
1117 p
->softirq_disable_ip
= 0;
1118 p
->softirq_disable_event
= 0;
1119 p
->hardirq_context
= 0;
1120 p
->softirq_context
= 0;
1122 #ifdef CONFIG_LOCKDEP
1123 p
->lockdep_depth
= 0; /* no locks held yet */
1124 p
->curr_chain_key
= 0;
1125 p
->lockdep_recursion
= 0;
1128 #ifdef CONFIG_DEBUG_MUTEXES
1129 p
->blocked_on
= NULL
; /* not blocked yet */
1131 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1132 p
->memcg_batch
.do_batch
= 0;
1133 p
->memcg_batch
.memcg
= NULL
;
1136 /* Perform scheduler related setup. Assign this task to a CPU. */
1137 sched_fork(p
, clone_flags
);
1139 retval
= perf_event_init_task(p
);
1141 goto bad_fork_cleanup_policy
;
1143 if ((retval
= audit_alloc(p
)))
1144 goto bad_fork_cleanup_policy
;
1145 /* copy all the process information */
1146 if ((retval
= copy_semundo(clone_flags
, p
)))
1147 goto bad_fork_cleanup_audit
;
1148 if ((retval
= copy_files(clone_flags
, p
)))
1149 goto bad_fork_cleanup_semundo
;
1150 if ((retval
= copy_fs(clone_flags
, p
)))
1151 goto bad_fork_cleanup_files
;
1152 if ((retval
= copy_sighand(clone_flags
, p
)))
1153 goto bad_fork_cleanup_fs
;
1154 if ((retval
= copy_signal(clone_flags
, p
)))
1155 goto bad_fork_cleanup_sighand
;
1156 if ((retval
= copy_mm(clone_flags
, p
)))
1157 goto bad_fork_cleanup_signal
;
1158 if ((retval
= copy_namespaces(clone_flags
, p
)))
1159 goto bad_fork_cleanup_mm
;
1160 if ((retval
= copy_io(clone_flags
, p
)))
1161 goto bad_fork_cleanup_namespaces
;
1162 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1164 goto bad_fork_cleanup_io
;
1166 if (pid
!= &init_struct_pid
) {
1168 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1170 goto bad_fork_cleanup_io
;
1172 if (clone_flags
& CLONE_NEWPID
) {
1173 retval
= pid_ns_prepare_proc(p
->nsproxy
->pid_ns
);
1175 goto bad_fork_free_pid
;
1179 p
->pid
= pid_nr(pid
);
1181 if (clone_flags
& CLONE_THREAD
)
1182 p
->tgid
= current
->tgid
;
1184 if (current
->nsproxy
!= p
->nsproxy
) {
1185 retval
= ns_cgroup_clone(p
, pid
);
1187 goto bad_fork_free_pid
;
1190 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1192 * Clear TID on mm_release()?
1194 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1196 p
->robust_list
= NULL
;
1197 #ifdef CONFIG_COMPAT
1198 p
->compat_robust_list
= NULL
;
1200 INIT_LIST_HEAD(&p
->pi_state_list
);
1201 p
->pi_state_cache
= NULL
;
1204 * sigaltstack should be cleared when sharing the same VM
1206 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1207 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1210 * Syscall tracing and stepping should be turned off in the
1211 * child regardless of CLONE_PTRACE.
1213 user_disable_single_step(p
);
1214 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1215 #ifdef TIF_SYSCALL_EMU
1216 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1218 clear_all_latency_tracing(p
);
1220 /* ok, now we should be set up.. */
1221 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1222 p
->pdeath_signal
= 0;
1226 * Ok, make it visible to the rest of the system.
1227 * We dont wake it up yet.
1229 p
->group_leader
= p
;
1230 INIT_LIST_HEAD(&p
->thread_group
);
1232 /* Now that the task is set up, run cgroup callbacks if
1233 * necessary. We need to run them before the task is visible
1234 * on the tasklist. */
1235 cgroup_fork_callbacks(p
);
1236 cgroup_callbacks_done
= 1;
1238 /* Need tasklist lock for parent etc handling! */
1239 write_lock_irq(&tasklist_lock
);
1241 /* CLONE_PARENT re-uses the old parent */
1242 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1243 p
->real_parent
= current
->real_parent
;
1244 p
->parent_exec_id
= current
->parent_exec_id
;
1246 p
->real_parent
= current
;
1247 p
->parent_exec_id
= current
->self_exec_id
;
1250 spin_lock(¤t
->sighand
->siglock
);
1253 * Process group and session signals need to be delivered to just the
1254 * parent before the fork or both the parent and the child after the
1255 * fork. Restart if a signal comes in before we add the new process to
1256 * it's process group.
1257 * A fatal signal pending means that current will exit, so the new
1258 * thread can't slip out of an OOM kill (or normal SIGKILL).
1260 recalc_sigpending();
1261 if (signal_pending(current
)) {
1262 spin_unlock(¤t
->sighand
->siglock
);
1263 write_unlock_irq(&tasklist_lock
);
1264 retval
= -ERESTARTNOINTR
;
1265 goto bad_fork_free_pid
;
1268 if (clone_flags
& CLONE_THREAD
) {
1269 current
->signal
->nr_threads
++;
1270 atomic_inc(¤t
->signal
->live
);
1271 atomic_inc(¤t
->signal
->sigcnt
);
1272 p
->group_leader
= current
->group_leader
;
1273 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1276 if (likely(p
->pid
)) {
1277 tracehook_finish_clone(p
, clone_flags
, trace
);
1279 if (thread_group_leader(p
)) {
1280 if (clone_flags
& CLONE_NEWPID
)
1281 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1283 p
->signal
->leader_pid
= pid
;
1284 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1285 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1286 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1287 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1288 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1289 __get_cpu_var(process_counts
)++;
1291 attach_pid(p
, PIDTYPE_PID
, pid
);
1296 spin_unlock(¤t
->sighand
->siglock
);
1297 write_unlock_irq(&tasklist_lock
);
1298 proc_fork_connector(p
);
1299 cgroup_post_fork(p
);
1304 if (pid
!= &init_struct_pid
)
1306 bad_fork_cleanup_io
:
1309 bad_fork_cleanup_namespaces
:
1310 exit_task_namespaces(p
);
1311 bad_fork_cleanup_mm
:
1314 if (p
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
)
1315 atomic_dec(&p
->mm
->oom_disable_count
);
1319 bad_fork_cleanup_signal
:
1320 if (!(clone_flags
& CLONE_THREAD
))
1321 put_signal_struct(p
->signal
);
1322 bad_fork_cleanup_sighand
:
1323 __cleanup_sighand(p
->sighand
);
1324 bad_fork_cleanup_fs
:
1325 exit_fs(p
); /* blocking */
1326 bad_fork_cleanup_files
:
1327 exit_files(p
); /* blocking */
1328 bad_fork_cleanup_semundo
:
1330 bad_fork_cleanup_audit
:
1332 bad_fork_cleanup_policy
:
1333 perf_event_free_task(p
);
1335 mpol_put(p
->mempolicy
);
1336 bad_fork_cleanup_cgroup
:
1338 cgroup_exit(p
, cgroup_callbacks_done
);
1339 delayacct_tsk_free(p
);
1340 module_put(task_thread_info(p
)->exec_domain
->module
);
1341 bad_fork_cleanup_count
:
1342 atomic_dec(&p
->cred
->user
->processes
);
1347 return ERR_PTR(retval
);
1350 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1352 memset(regs
, 0, sizeof(struct pt_regs
));
1356 static inline void init_idle_pids(struct pid_link
*links
)
1360 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1361 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1362 links
[type
].pid
= &init_struct_pid
;
1366 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1368 struct task_struct
*task
;
1369 struct pt_regs regs
;
1371 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1372 &init_struct_pid
, 0);
1373 if (!IS_ERR(task
)) {
1374 init_idle_pids(task
->pids
);
1375 init_idle(task
, cpu
);
1382 * Ok, this is the main fork-routine.
1384 * It copies the process, and if successful kick-starts
1385 * it and waits for it to finish using the VM if required.
1387 long do_fork(unsigned long clone_flags
,
1388 unsigned long stack_start
,
1389 struct pt_regs
*regs
,
1390 unsigned long stack_size
,
1391 int __user
*parent_tidptr
,
1392 int __user
*child_tidptr
)
1394 struct task_struct
*p
;
1399 * Do some preliminary argument and permissions checking before we
1400 * actually start allocating stuff
1402 if (clone_flags
& CLONE_NEWUSER
) {
1403 if (clone_flags
& CLONE_THREAD
)
1405 /* hopefully this check will go away when userns support is
1408 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1409 !capable(CAP_SETGID
))
1414 * We hope to recycle these flags after 2.6.26
1416 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1417 static int __read_mostly count
= 100;
1419 if (count
> 0 && printk_ratelimit()) {
1420 char comm
[TASK_COMM_LEN
];
1423 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1424 "clone flags 0x%lx\n",
1425 get_task_comm(comm
, current
),
1426 clone_flags
& CLONE_STOPPED
);
1431 * When called from kernel_thread, don't do user tracing stuff.
1433 if (likely(user_mode(regs
)))
1434 trace
= tracehook_prepare_clone(clone_flags
);
1436 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1437 child_tidptr
, NULL
, trace
);
1439 * Do this prior waking up the new thread - the thread pointer
1440 * might get invalid after that point, if the thread exits quickly.
1443 struct completion vfork
;
1445 trace_sched_process_fork(current
, p
);
1447 nr
= task_pid_vnr(p
);
1449 if (clone_flags
& CLONE_PARENT_SETTID
)
1450 put_user(nr
, parent_tidptr
);
1452 if (clone_flags
& CLONE_VFORK
) {
1453 p
->vfork_done
= &vfork
;
1454 init_completion(&vfork
);
1457 audit_finish_fork(p
);
1458 tracehook_report_clone(regs
, clone_flags
, nr
, p
);
1461 * We set PF_STARTING at creation in case tracing wants to
1462 * use this to distinguish a fully live task from one that
1463 * hasn't gotten to tracehook_report_clone() yet. Now we
1464 * clear it and set the child going.
1466 p
->flags
&= ~PF_STARTING
;
1468 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1470 * We'll start up with an immediate SIGSTOP.
1472 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1473 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1474 __set_task_state(p
, TASK_STOPPED
);
1476 wake_up_new_task(p
, clone_flags
);
1479 tracehook_report_clone_complete(trace
, regs
,
1480 clone_flags
, nr
, p
);
1482 if (clone_flags
& CLONE_VFORK
) {
1483 freezer_do_not_count();
1484 wait_for_completion(&vfork
);
1486 tracehook_report_vfork_done(p
, nr
);
1494 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1495 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1498 static void sighand_ctor(void *data
)
1500 struct sighand_struct
*sighand
= data
;
1502 spin_lock_init(&sighand
->siglock
);
1503 init_waitqueue_head(&sighand
->signalfd_wqh
);
1506 void __init
proc_caches_init(void)
1508 sighand_cachep
= kmem_cache_create("sighand_cache",
1509 sizeof(struct sighand_struct
), 0,
1510 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1511 SLAB_NOTRACK
, sighand_ctor
);
1512 signal_cachep
= kmem_cache_create("signal_cache",
1513 sizeof(struct signal_struct
), 0,
1514 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1515 files_cachep
= kmem_cache_create("files_cache",
1516 sizeof(struct files_struct
), 0,
1517 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1518 fs_cachep
= kmem_cache_create("fs_cache",
1519 sizeof(struct fs_struct
), 0,
1520 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1521 mm_cachep
= kmem_cache_create("mm_struct",
1522 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1523 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1524 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1529 * Check constraints on flags passed to the unshare system call and
1530 * force unsharing of additional process context as appropriate.
1532 static void check_unshare_flags(unsigned long *flags_ptr
)
1535 * If unsharing a thread from a thread group, must also
1538 if (*flags_ptr
& CLONE_THREAD
)
1539 *flags_ptr
|= CLONE_VM
;
1542 * If unsharing vm, must also unshare signal handlers.
1544 if (*flags_ptr
& CLONE_VM
)
1545 *flags_ptr
|= CLONE_SIGHAND
;
1548 * If unsharing namespace, must also unshare filesystem information.
1550 if (*flags_ptr
& CLONE_NEWNS
)
1551 *flags_ptr
|= CLONE_FS
;
1555 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1557 static int unshare_thread(unsigned long unshare_flags
)
1559 if (unshare_flags
& CLONE_THREAD
)
1566 * Unshare the filesystem structure if it is being shared
1568 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1570 struct fs_struct
*fs
= current
->fs
;
1572 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1575 /* don't need lock here; in the worst case we'll do useless copy */
1579 *new_fsp
= copy_fs_struct(fs
);
1587 * Unsharing of sighand is not supported yet
1589 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1591 struct sighand_struct
*sigh
= current
->sighand
;
1593 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1600 * Unshare vm if it is being shared
1602 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1604 struct mm_struct
*mm
= current
->mm
;
1606 if ((unshare_flags
& CLONE_VM
) &&
1607 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1615 * Unshare file descriptor table if it is being shared
1617 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1619 struct files_struct
*fd
= current
->files
;
1622 if ((unshare_flags
& CLONE_FILES
) &&
1623 (fd
&& atomic_read(&fd
->count
) > 1)) {
1624 *new_fdp
= dup_fd(fd
, &error
);
1633 * unshare allows a process to 'unshare' part of the process
1634 * context which was originally shared using clone. copy_*
1635 * functions used by do_fork() cannot be used here directly
1636 * because they modify an inactive task_struct that is being
1637 * constructed. Here we are modifying the current, active,
1640 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1643 struct fs_struct
*fs
, *new_fs
= NULL
;
1644 struct sighand_struct
*new_sigh
= NULL
;
1645 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1646 struct files_struct
*fd
, *new_fd
= NULL
;
1647 struct nsproxy
*new_nsproxy
= NULL
;
1650 check_unshare_flags(&unshare_flags
);
1652 /* Return -EINVAL for all unsupported flags */
1654 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1655 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1656 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
))
1657 goto bad_unshare_out
;
1660 * CLONE_NEWIPC must also detach from the undolist: after switching
1661 * to a new ipc namespace, the semaphore arrays from the old
1662 * namespace are unreachable.
1664 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1666 if ((err
= unshare_thread(unshare_flags
)))
1667 goto bad_unshare_out
;
1668 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1669 goto bad_unshare_cleanup_thread
;
1670 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1671 goto bad_unshare_cleanup_fs
;
1672 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1673 goto bad_unshare_cleanup_sigh
;
1674 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1675 goto bad_unshare_cleanup_vm
;
1676 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1678 goto bad_unshare_cleanup_fd
;
1680 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1683 * CLONE_SYSVSEM is equivalent to sys_exit().
1689 switch_task_namespaces(current
, new_nsproxy
);
1697 spin_lock(&fs
->lock
);
1698 current
->fs
= new_fs
;
1703 spin_unlock(&fs
->lock
);
1708 active_mm
= current
->active_mm
;
1709 current
->mm
= new_mm
;
1710 current
->active_mm
= new_mm
;
1711 if (current
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
) {
1712 atomic_dec(&mm
->oom_disable_count
);
1713 atomic_inc(&new_mm
->oom_disable_count
);
1715 activate_mm(active_mm
, new_mm
);
1720 fd
= current
->files
;
1721 current
->files
= new_fd
;
1725 task_unlock(current
);
1729 put_nsproxy(new_nsproxy
);
1731 bad_unshare_cleanup_fd
:
1733 put_files_struct(new_fd
);
1735 bad_unshare_cleanup_vm
:
1739 bad_unshare_cleanup_sigh
:
1741 if (atomic_dec_and_test(&new_sigh
->count
))
1742 kmem_cache_free(sighand_cachep
, new_sigh
);
1744 bad_unshare_cleanup_fs
:
1746 free_fs_struct(new_fs
);
1748 bad_unshare_cleanup_thread
:
1754 * Helper to unshare the files of the current task.
1755 * We don't want to expose copy_files internals to
1756 * the exec layer of the kernel.
1759 int unshare_files(struct files_struct
**displaced
)
1761 struct task_struct
*task
= current
;
1762 struct files_struct
*copy
= NULL
;
1765 error
= unshare_fd(CLONE_FILES
, ©
);
1766 if (error
|| !copy
) {
1770 *displaced
= task
->files
;