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>
69 #include <asm/pgtable.h>
70 #include <asm/pgalloc.h>
71 #include <asm/uaccess.h>
72 #include <asm/mmu_context.h>
73 #include <asm/cacheflush.h>
74 #include <asm/tlbflush.h>
76 #include <trace/events/sched.h>
79 * Protected counters by write_lock_irq(&tasklist_lock)
81 unsigned long total_forks
; /* Handle normal Linux uptimes. */
82 int nr_threads
; /* The idle threads do not count.. */
84 int max_threads
; /* tunable limit on nr_threads */
86 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
88 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
89 EXPORT_SYMBOL_GPL(tasklist_lock
);
91 int nr_processes(void)
96 for_each_possible_cpu(cpu
)
97 total
+= per_cpu(process_counts
, cpu
);
102 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
103 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
104 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
105 static struct kmem_cache
*task_struct_cachep
;
108 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
109 static inline struct thread_info
*alloc_thread_info(struct task_struct
*tsk
)
111 #ifdef CONFIG_DEBUG_STACK_USAGE
112 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
114 gfp_t mask
= GFP_KERNEL
;
116 return (struct thread_info
*)__get_free_pages(mask
, THREAD_SIZE_ORDER
);
119 static inline void free_thread_info(struct thread_info
*ti
)
121 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
125 /* SLAB cache for signal_struct structures (tsk->signal) */
126 static struct kmem_cache
*signal_cachep
;
128 /* SLAB cache for sighand_struct structures (tsk->sighand) */
129 struct kmem_cache
*sighand_cachep
;
131 /* SLAB cache for files_struct structures (tsk->files) */
132 struct kmem_cache
*files_cachep
;
134 /* SLAB cache for fs_struct structures (tsk->fs) */
135 struct kmem_cache
*fs_cachep
;
137 /* SLAB cache for vm_area_struct structures */
138 struct kmem_cache
*vm_area_cachep
;
140 /* SLAB cache for mm_struct structures (tsk->mm) */
141 static struct kmem_cache
*mm_cachep
;
143 static void account_kernel_stack(struct thread_info
*ti
, int account
)
145 struct zone
*zone
= page_zone(virt_to_page(ti
));
147 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
150 void free_task(struct task_struct
*tsk
)
152 prop_local_destroy_single(&tsk
->dirties
);
153 account_kernel_stack(tsk
->stack
, -1);
154 free_thread_info(tsk
->stack
);
155 rt_mutex_debug_task_free(tsk
);
156 ftrace_graph_exit_task(tsk
);
157 free_task_struct(tsk
);
159 EXPORT_SYMBOL(free_task
);
161 void __put_task_struct(struct task_struct
*tsk
)
163 WARN_ON(!tsk
->exit_state
);
164 WARN_ON(atomic_read(&tsk
->usage
));
165 WARN_ON(tsk
== current
);
168 delayacct_tsk_free(tsk
);
170 if (!profile_handoff_task(tsk
))
175 * macro override instead of weak attribute alias, to workaround
176 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
178 #ifndef arch_task_cache_init
179 #define arch_task_cache_init()
182 void __init
fork_init(unsigned long mempages
)
184 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
185 #ifndef ARCH_MIN_TASKALIGN
186 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
188 /* create a slab on which task_structs can be allocated */
190 kmem_cache_create("task_struct", sizeof(struct task_struct
),
191 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
194 /* do the arch specific task caches init */
195 arch_task_cache_init();
198 * The default maximum number of threads is set to a safe
199 * value: the thread structures can take up at most half
202 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
205 * we need to allow at least 20 threads to boot a system
210 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
211 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
212 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
213 init_task
.signal
->rlim
[RLIMIT_NPROC
];
216 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
217 struct task_struct
*src
)
223 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
225 struct task_struct
*tsk
;
226 struct thread_info
*ti
;
227 unsigned long *stackend
;
231 prepare_to_copy(orig
);
233 tsk
= alloc_task_struct();
237 ti
= alloc_thread_info(tsk
);
239 free_task_struct(tsk
);
243 err
= arch_dup_task_struct(tsk
, orig
);
249 err
= prop_local_init_single(&tsk
->dirties
);
253 setup_thread_stack(tsk
, orig
);
254 clear_user_return_notifier(tsk
);
255 stackend
= end_of_stack(tsk
);
256 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
258 #ifdef CONFIG_CC_STACKPROTECTOR
259 tsk
->stack_canary
= get_random_int();
262 /* One for us, one for whoever does the "release_task()" (usually parent) */
263 atomic_set(&tsk
->usage
,2);
264 atomic_set(&tsk
->fs_excl
, 0);
265 #ifdef CONFIG_BLK_DEV_IO_TRACE
268 tsk
->splice_pipe
= NULL
;
270 account_kernel_stack(ti
, 1);
275 free_thread_info(ti
);
276 free_task_struct(tsk
);
281 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
283 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
284 struct rb_node
**rb_link
, *rb_parent
;
286 unsigned long charge
;
287 struct mempolicy
*pol
;
289 down_write(&oldmm
->mmap_sem
);
290 flush_cache_dup_mm(oldmm
);
292 * Not linked in yet - no deadlock potential:
294 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
298 mm
->mmap_cache
= NULL
;
299 mm
->free_area_cache
= oldmm
->mmap_base
;
300 mm
->cached_hole_size
= ~0UL;
302 cpumask_clear(mm_cpumask(mm
));
304 rb_link
= &mm
->mm_rb
.rb_node
;
307 retval
= ksm_fork(mm
, oldmm
);
311 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
314 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
315 long pages
= vma_pages(mpnt
);
316 mm
->total_vm
-= pages
;
317 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
322 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
323 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
324 if (security_vm_enough_memory(len
))
328 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
332 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
333 pol
= mpol_dup(vma_policy(mpnt
));
334 retval
= PTR_ERR(pol
);
336 goto fail_nomem_policy
;
337 vma_set_policy(tmp
, pol
);
338 if (anon_vma_fork(tmp
, mpnt
))
339 goto fail_nomem_anon_vma_fork
;
340 tmp
->vm_flags
&= ~VM_LOCKED
;
345 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
346 struct address_space
*mapping
= file
->f_mapping
;
349 if (tmp
->vm_flags
& VM_DENYWRITE
)
350 atomic_dec(&inode
->i_writecount
);
351 spin_lock(&mapping
->i_mmap_lock
);
352 if (tmp
->vm_flags
& VM_SHARED
)
353 mapping
->i_mmap_writable
++;
354 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
355 flush_dcache_mmap_lock(mapping
);
356 /* insert tmp into the share list, just after mpnt */
357 vma_prio_tree_add(tmp
, mpnt
);
358 flush_dcache_mmap_unlock(mapping
);
359 spin_unlock(&mapping
->i_mmap_lock
);
363 * Clear hugetlb-related page reserves for children. This only
364 * affects MAP_PRIVATE mappings. Faults generated by the child
365 * are not guaranteed to succeed, even if read-only
367 if (is_vm_hugetlb_page(tmp
))
368 reset_vma_resv_huge_pages(tmp
);
371 * Link in the new vma and copy the page table entries.
374 pprev
= &tmp
->vm_next
;
376 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
377 rb_link
= &tmp
->vm_rb
.rb_right
;
378 rb_parent
= &tmp
->vm_rb
;
381 retval
= copy_page_range(mm
, oldmm
, mpnt
);
383 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
384 tmp
->vm_ops
->open(tmp
);
389 /* a new mm has just been created */
390 arch_dup_mmap(oldmm
, mm
);
393 up_write(&mm
->mmap_sem
);
395 up_write(&oldmm
->mmap_sem
);
397 fail_nomem_anon_vma_fork
:
400 kmem_cache_free(vm_area_cachep
, tmp
);
403 vm_unacct_memory(charge
);
407 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
409 mm
->pgd
= pgd_alloc(mm
);
410 if (unlikely(!mm
->pgd
))
415 static inline void mm_free_pgd(struct mm_struct
* mm
)
417 pgd_free(mm
, mm
->pgd
);
420 #define dup_mmap(mm, oldmm) (0)
421 #define mm_alloc_pgd(mm) (0)
422 #define mm_free_pgd(mm)
423 #endif /* CONFIG_MMU */
425 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
427 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
428 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
430 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
432 static int __init
coredump_filter_setup(char *s
)
434 default_dump_filter
=
435 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
436 MMF_DUMP_FILTER_MASK
;
440 __setup("coredump_filter=", coredump_filter_setup
);
442 #include <linux/init_task.h>
444 static void mm_init_aio(struct mm_struct
*mm
)
447 spin_lock_init(&mm
->ioctx_lock
);
448 INIT_HLIST_HEAD(&mm
->ioctx_list
);
452 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
454 atomic_set(&mm
->mm_users
, 1);
455 atomic_set(&mm
->mm_count
, 1);
456 init_rwsem(&mm
->mmap_sem
);
457 INIT_LIST_HEAD(&mm
->mmlist
);
458 mm
->flags
= (current
->mm
) ?
459 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
460 mm
->core_state
= NULL
;
462 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
463 spin_lock_init(&mm
->page_table_lock
);
464 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
465 mm
->cached_hole_size
= ~0UL;
467 mm_init_owner(mm
, p
);
469 if (likely(!mm_alloc_pgd(mm
))) {
471 mmu_notifier_mm_init(mm
);
480 * Allocate and initialize an mm_struct.
482 struct mm_struct
* mm_alloc(void)
484 struct mm_struct
* mm
;
488 memset(mm
, 0, sizeof(*mm
));
489 mm
= mm_init(mm
, current
);
495 * Called when the last reference to the mm
496 * is dropped: either by a lazy thread or by
497 * mmput. Free the page directory and the mm.
499 void __mmdrop(struct mm_struct
*mm
)
501 BUG_ON(mm
== &init_mm
);
504 mmu_notifier_mm_destroy(mm
);
507 EXPORT_SYMBOL_GPL(__mmdrop
);
510 * Decrement the use count and release all resources for an mm.
512 void mmput(struct mm_struct
*mm
)
516 if (atomic_dec_and_test(&mm
->mm_users
)) {
520 set_mm_exe_file(mm
, NULL
);
521 if (!list_empty(&mm
->mmlist
)) {
522 spin_lock(&mmlist_lock
);
523 list_del(&mm
->mmlist
);
524 spin_unlock(&mmlist_lock
);
528 module_put(mm
->binfmt
->module
);
532 EXPORT_SYMBOL_GPL(mmput
);
535 * get_task_mm - acquire a reference to the task's mm
537 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
538 * this kernel workthread has transiently adopted a user mm with use_mm,
539 * to do its AIO) is not set and if so returns a reference to it, after
540 * bumping up the use count. User must release the mm via mmput()
541 * after use. Typically used by /proc and ptrace.
543 struct mm_struct
*get_task_mm(struct task_struct
*task
)
545 struct mm_struct
*mm
;
550 if (task
->flags
& PF_KTHREAD
)
553 atomic_inc(&mm
->mm_users
);
558 EXPORT_SYMBOL_GPL(get_task_mm
);
560 /* Please note the differences between mmput and mm_release.
561 * mmput is called whenever we stop holding onto a mm_struct,
562 * error success whatever.
564 * mm_release is called after a mm_struct has been removed
565 * from the current process.
567 * This difference is important for error handling, when we
568 * only half set up a mm_struct for a new process and need to restore
569 * the old one. Because we mmput the new mm_struct before
570 * restoring the old one. . .
571 * Eric Biederman 10 January 1998
573 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
575 struct completion
*vfork_done
= tsk
->vfork_done
;
577 /* Get rid of any futexes when releasing the mm */
579 if (unlikely(tsk
->robust_list
)) {
580 exit_robust_list(tsk
);
581 tsk
->robust_list
= NULL
;
584 if (unlikely(tsk
->compat_robust_list
)) {
585 compat_exit_robust_list(tsk
);
586 tsk
->compat_robust_list
= NULL
;
589 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
590 exit_pi_state_list(tsk
);
593 /* Get rid of any cached register state */
594 deactivate_mm(tsk
, mm
);
596 /* notify parent sleeping on vfork() */
598 tsk
->vfork_done
= NULL
;
599 complete(vfork_done
);
603 * If we're exiting normally, clear a user-space tid field if
604 * requested. We leave this alone when dying by signal, to leave
605 * the value intact in a core dump, and to save the unnecessary
606 * trouble otherwise. Userland only wants this done for a sys_exit.
608 if (tsk
->clear_child_tid
) {
609 if (!(tsk
->flags
& PF_SIGNALED
) &&
610 atomic_read(&mm
->mm_users
) > 1) {
612 * We don't check the error code - if userspace has
613 * not set up a proper pointer then tough luck.
615 put_user(0, tsk
->clear_child_tid
);
616 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
619 tsk
->clear_child_tid
= NULL
;
624 * Allocate a new mm structure and copy contents from the
625 * mm structure of the passed in task structure.
627 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
629 struct mm_struct
*mm
, *oldmm
= current
->mm
;
639 memcpy(mm
, oldmm
, sizeof(*mm
));
641 /* Initializing for Swap token stuff */
642 mm
->token_priority
= 0;
643 mm
->last_interval
= 0;
645 if (!mm_init(mm
, tsk
))
648 if (init_new_context(tsk
, mm
))
651 dup_mm_exe_file(oldmm
, mm
);
653 err
= dup_mmap(mm
, oldmm
);
657 mm
->hiwater_rss
= get_mm_rss(mm
);
658 mm
->hiwater_vm
= mm
->total_vm
;
660 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
666 /* don't put binfmt in mmput, we haven't got module yet */
675 * If init_new_context() failed, we cannot use mmput() to free the mm
676 * because it calls destroy_context()
683 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
685 struct mm_struct
* mm
, *oldmm
;
688 tsk
->min_flt
= tsk
->maj_flt
= 0;
689 tsk
->nvcsw
= tsk
->nivcsw
= 0;
690 #ifdef CONFIG_DETECT_HUNG_TASK
691 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
695 tsk
->active_mm
= NULL
;
698 * Are we cloning a kernel thread?
700 * We need to steal a active VM for that..
706 if (clone_flags
& CLONE_VM
) {
707 atomic_inc(&oldmm
->mm_users
);
718 /* Initializing for Swap token stuff */
719 mm
->token_priority
= 0;
720 mm
->last_interval
= 0;
730 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
732 struct fs_struct
*fs
= current
->fs
;
733 if (clone_flags
& CLONE_FS
) {
734 /* tsk->fs is already what we want */
735 write_lock(&fs
->lock
);
737 write_unlock(&fs
->lock
);
741 write_unlock(&fs
->lock
);
744 tsk
->fs
= copy_fs_struct(fs
);
750 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
752 struct files_struct
*oldf
, *newf
;
756 * A background process may not have any files ...
758 oldf
= current
->files
;
762 if (clone_flags
& CLONE_FILES
) {
763 atomic_inc(&oldf
->count
);
767 newf
= dup_fd(oldf
, &error
);
777 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
780 struct io_context
*ioc
= current
->io_context
;
785 * Share io context with parent, if CLONE_IO is set
787 if (clone_flags
& CLONE_IO
) {
788 tsk
->io_context
= ioc_task_link(ioc
);
789 if (unlikely(!tsk
->io_context
))
791 } else if (ioprio_valid(ioc
->ioprio
)) {
792 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
793 if (unlikely(!tsk
->io_context
))
796 tsk
->io_context
->ioprio
= ioc
->ioprio
;
802 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
804 struct sighand_struct
*sig
;
806 if (clone_flags
& CLONE_SIGHAND
) {
807 atomic_inc(¤t
->sighand
->count
);
810 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
811 rcu_assign_pointer(tsk
->sighand
, sig
);
814 atomic_set(&sig
->count
, 1);
815 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
819 void __cleanup_sighand(struct sighand_struct
*sighand
)
821 if (atomic_dec_and_test(&sighand
->count
))
822 kmem_cache_free(sighand_cachep
, sighand
);
827 * Initialize POSIX timer handling for a thread group.
829 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
831 unsigned long cpu_limit
;
833 /* Thread group counters. */
834 thread_group_cputime_init(sig
);
836 /* Expiration times and increments. */
837 sig
->it
[CPUCLOCK_PROF
].expires
= cputime_zero
;
838 sig
->it
[CPUCLOCK_PROF
].incr
= cputime_zero
;
839 sig
->it
[CPUCLOCK_VIRT
].expires
= cputime_zero
;
840 sig
->it
[CPUCLOCK_VIRT
].incr
= cputime_zero
;
842 /* Cached expiration times. */
843 sig
->cputime_expires
.prof_exp
= cputime_zero
;
844 sig
->cputime_expires
.virt_exp
= cputime_zero
;
845 sig
->cputime_expires
.sched_exp
= 0;
847 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
848 if (cpu_limit
!= RLIM_INFINITY
) {
849 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
850 sig
->cputimer
.running
= 1;
853 /* The timer lists. */
854 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
855 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
856 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
859 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
861 struct signal_struct
*sig
;
863 if (clone_flags
& CLONE_THREAD
)
866 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
871 atomic_set(&sig
->count
, 1);
872 atomic_set(&sig
->live
, 1);
873 init_waitqueue_head(&sig
->wait_chldexit
);
875 if (clone_flags
& CLONE_NEWPID
)
876 sig
->flags
|= SIGNAL_UNKILLABLE
;
877 sig
->group_exit_code
= 0;
878 sig
->group_exit_task
= NULL
;
879 sig
->group_stop_count
= 0;
880 sig
->curr_target
= tsk
;
881 init_sigpending(&sig
->shared_pending
);
882 INIT_LIST_HEAD(&sig
->posix_timers
);
884 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
885 sig
->it_real_incr
.tv64
= 0;
886 sig
->real_timer
.function
= it_real_fn
;
888 sig
->leader
= 0; /* session leadership doesn't inherit */
889 sig
->tty_old_pgrp
= NULL
;
892 sig
->utime
= sig
->stime
= sig
->cutime
= sig
->cstime
= cputime_zero
;
893 sig
->gtime
= cputime_zero
;
894 sig
->cgtime
= cputime_zero
;
895 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
896 sig
->prev_utime
= sig
->prev_stime
= cputime_zero
;
898 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
899 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
900 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
901 sig
->maxrss
= sig
->cmaxrss
= 0;
902 task_io_accounting_init(&sig
->ioac
);
903 sig
->sum_sched_runtime
= 0;
904 taskstats_tgid_init(sig
);
906 task_lock(current
->group_leader
);
907 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
908 task_unlock(current
->group_leader
);
910 posix_cpu_timers_init_group(sig
);
912 acct_init_pacct(&sig
->pacct
);
916 sig
->oom_adj
= current
->signal
->oom_adj
;
921 void __cleanup_signal(struct signal_struct
*sig
)
923 thread_group_cputime_free(sig
);
924 tty_kref_put(sig
->tty
);
925 kmem_cache_free(signal_cachep
, sig
);
928 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
930 unsigned long new_flags
= p
->flags
;
932 new_flags
&= ~PF_SUPERPRIV
;
933 new_flags
|= PF_FORKNOEXEC
;
934 new_flags
|= PF_STARTING
;
935 p
->flags
= new_flags
;
936 clear_freeze_flag(p
);
939 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
941 current
->clear_child_tid
= tidptr
;
943 return task_pid_vnr(current
);
946 static void rt_mutex_init_task(struct task_struct
*p
)
948 raw_spin_lock_init(&p
->pi_lock
);
949 #ifdef CONFIG_RT_MUTEXES
950 plist_head_init_raw(&p
->pi_waiters
, &p
->pi_lock
);
951 p
->pi_blocked_on
= NULL
;
955 #ifdef CONFIG_MM_OWNER
956 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
960 #endif /* CONFIG_MM_OWNER */
963 * Initialize POSIX timer handling for a single task.
965 static void posix_cpu_timers_init(struct task_struct
*tsk
)
967 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
968 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
969 tsk
->cputime_expires
.sched_exp
= 0;
970 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
971 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
972 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
976 * This creates a new process as a copy of the old one,
977 * but does not actually start it yet.
979 * It copies the registers, and all the appropriate
980 * parts of the process environment (as per the clone
981 * flags). The actual kick-off is left to the caller.
983 static struct task_struct
*copy_process(unsigned long clone_flags
,
984 unsigned long stack_start
,
985 struct pt_regs
*regs
,
986 unsigned long stack_size
,
987 int __user
*child_tidptr
,
992 struct task_struct
*p
;
993 int cgroup_callbacks_done
= 0;
995 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
996 return ERR_PTR(-EINVAL
);
999 * Thread groups must share signals as well, and detached threads
1000 * can only be started up within the thread group.
1002 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1003 return ERR_PTR(-EINVAL
);
1006 * Shared signal handlers imply shared VM. By way of the above,
1007 * thread groups also imply shared VM. Blocking this case allows
1008 * for various simplifications in other code.
1010 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1011 return ERR_PTR(-EINVAL
);
1014 * Siblings of global init remain as zombies on exit since they are
1015 * not reaped by their parent (swapper). To solve this and to avoid
1016 * multi-rooted process trees, prevent global and container-inits
1017 * from creating siblings.
1019 if ((clone_flags
& CLONE_PARENT
) &&
1020 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1021 return ERR_PTR(-EINVAL
);
1023 retval
= security_task_create(clone_flags
);
1028 p
= dup_task_struct(current
);
1032 ftrace_graph_init_task(p
);
1034 rt_mutex_init_task(p
);
1036 #ifdef CONFIG_PROVE_LOCKING
1037 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1038 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1041 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1042 task_rlimit(p
, RLIMIT_NPROC
)) {
1043 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1044 p
->real_cred
->user
!= INIT_USER
)
1048 retval
= copy_creds(p
, clone_flags
);
1053 * If multiple threads are within copy_process(), then this check
1054 * triggers too late. This doesn't hurt, the check is only there
1055 * to stop root fork bombs.
1058 if (nr_threads
>= max_threads
)
1059 goto bad_fork_cleanup_count
;
1061 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1062 goto bad_fork_cleanup_count
;
1065 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1066 copy_flags(clone_flags
, p
);
1067 INIT_LIST_HEAD(&p
->children
);
1068 INIT_LIST_HEAD(&p
->sibling
);
1069 rcu_copy_process(p
);
1070 p
->vfork_done
= NULL
;
1071 spin_lock_init(&p
->alloc_lock
);
1073 init_sigpending(&p
->pending
);
1075 p
->utime
= cputime_zero
;
1076 p
->stime
= cputime_zero
;
1077 p
->gtime
= cputime_zero
;
1078 p
->utimescaled
= cputime_zero
;
1079 p
->stimescaled
= cputime_zero
;
1080 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1081 p
->prev_utime
= cputime_zero
;
1082 p
->prev_stime
= cputime_zero
;
1085 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1087 task_io_accounting_init(&p
->ioac
);
1088 acct_clear_integrals(p
);
1090 posix_cpu_timers_init(p
);
1092 p
->lock_depth
= -1; /* -1 = no lock */
1093 do_posix_clock_monotonic_gettime(&p
->start_time
);
1094 p
->real_start_time
= p
->start_time
;
1095 monotonic_to_bootbased(&p
->real_start_time
);
1096 p
->io_context
= NULL
;
1097 p
->audit_context
= NULL
;
1100 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1101 if (IS_ERR(p
->mempolicy
)) {
1102 retval
= PTR_ERR(p
->mempolicy
);
1103 p
->mempolicy
= NULL
;
1104 goto bad_fork_cleanup_cgroup
;
1106 mpol_fix_fork_child_flag(p
);
1108 #ifdef CONFIG_TRACE_IRQFLAGS
1110 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1111 p
->hardirqs_enabled
= 1;
1113 p
->hardirqs_enabled
= 0;
1115 p
->hardirq_enable_ip
= 0;
1116 p
->hardirq_enable_event
= 0;
1117 p
->hardirq_disable_ip
= _THIS_IP_
;
1118 p
->hardirq_disable_event
= 0;
1119 p
->softirqs_enabled
= 1;
1120 p
->softirq_enable_ip
= _THIS_IP_
;
1121 p
->softirq_enable_event
= 0;
1122 p
->softirq_disable_ip
= 0;
1123 p
->softirq_disable_event
= 0;
1124 p
->hardirq_context
= 0;
1125 p
->softirq_context
= 0;
1127 #ifdef CONFIG_LOCKDEP
1128 p
->lockdep_depth
= 0; /* no locks held yet */
1129 p
->curr_chain_key
= 0;
1130 p
->lockdep_recursion
= 0;
1133 #ifdef CONFIG_DEBUG_MUTEXES
1134 p
->blocked_on
= NULL
; /* not blocked yet */
1136 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1137 p
->memcg_batch
.do_batch
= 0;
1138 p
->memcg_batch
.memcg
= NULL
;
1143 p
->stack_start
= stack_start
;
1145 /* Perform scheduler related setup. Assign this task to a CPU. */
1146 sched_fork(p
, clone_flags
);
1148 retval
= perf_event_init_task(p
);
1150 goto bad_fork_cleanup_policy
;
1152 if ((retval
= audit_alloc(p
)))
1153 goto bad_fork_cleanup_policy
;
1154 /* copy all the process information */
1155 if ((retval
= copy_semundo(clone_flags
, p
)))
1156 goto bad_fork_cleanup_audit
;
1157 if ((retval
= copy_files(clone_flags
, p
)))
1158 goto bad_fork_cleanup_semundo
;
1159 if ((retval
= copy_fs(clone_flags
, p
)))
1160 goto bad_fork_cleanup_files
;
1161 if ((retval
= copy_sighand(clone_flags
, p
)))
1162 goto bad_fork_cleanup_fs
;
1163 if ((retval
= copy_signal(clone_flags
, p
)))
1164 goto bad_fork_cleanup_sighand
;
1165 if ((retval
= copy_mm(clone_flags
, p
)))
1166 goto bad_fork_cleanup_signal
;
1167 if ((retval
= copy_namespaces(clone_flags
, p
)))
1168 goto bad_fork_cleanup_mm
;
1169 if ((retval
= copy_io(clone_flags
, p
)))
1170 goto bad_fork_cleanup_namespaces
;
1171 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1173 goto bad_fork_cleanup_io
;
1175 if (pid
!= &init_struct_pid
) {
1177 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1179 goto bad_fork_cleanup_io
;
1181 if (clone_flags
& CLONE_NEWPID
) {
1182 retval
= pid_ns_prepare_proc(p
->nsproxy
->pid_ns
);
1184 goto bad_fork_free_pid
;
1188 p
->pid
= pid_nr(pid
);
1190 if (clone_flags
& CLONE_THREAD
)
1191 p
->tgid
= current
->tgid
;
1193 if (current
->nsproxy
!= p
->nsproxy
) {
1194 retval
= ns_cgroup_clone(p
, pid
);
1196 goto bad_fork_free_pid
;
1199 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1201 * Clear TID on mm_release()?
1203 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1205 p
->robust_list
= NULL
;
1206 #ifdef CONFIG_COMPAT
1207 p
->compat_robust_list
= NULL
;
1209 INIT_LIST_HEAD(&p
->pi_state_list
);
1210 p
->pi_state_cache
= NULL
;
1213 * sigaltstack should be cleared when sharing the same VM
1215 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1216 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1219 * Syscall tracing and stepping should be turned off in the
1220 * child regardless of CLONE_PTRACE.
1222 user_disable_single_step(p
);
1223 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1224 #ifdef TIF_SYSCALL_EMU
1225 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1227 clear_all_latency_tracing(p
);
1229 /* ok, now we should be set up.. */
1230 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1231 p
->pdeath_signal
= 0;
1235 * Ok, make it visible to the rest of the system.
1236 * We dont wake it up yet.
1238 p
->group_leader
= p
;
1239 INIT_LIST_HEAD(&p
->thread_group
);
1241 /* Now that the task is set up, run cgroup callbacks if
1242 * necessary. We need to run them before the task is visible
1243 * on the tasklist. */
1244 cgroup_fork_callbacks(p
);
1245 cgroup_callbacks_done
= 1;
1247 /* Need tasklist lock for parent etc handling! */
1248 write_lock_irq(&tasklist_lock
);
1250 /* CLONE_PARENT re-uses the old parent */
1251 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1252 p
->real_parent
= current
->real_parent
;
1253 p
->parent_exec_id
= current
->parent_exec_id
;
1255 p
->real_parent
= current
;
1256 p
->parent_exec_id
= current
->self_exec_id
;
1259 spin_lock(¤t
->sighand
->siglock
);
1262 * Process group and session signals need to be delivered to just the
1263 * parent before the fork or both the parent and the child after the
1264 * fork. Restart if a signal comes in before we add the new process to
1265 * it's process group.
1266 * A fatal signal pending means that current will exit, so the new
1267 * thread can't slip out of an OOM kill (or normal SIGKILL).
1269 recalc_sigpending();
1270 if (signal_pending(current
)) {
1271 spin_unlock(¤t
->sighand
->siglock
);
1272 write_unlock_irq(&tasklist_lock
);
1273 retval
= -ERESTARTNOINTR
;
1274 goto bad_fork_free_pid
;
1277 if (clone_flags
& CLONE_THREAD
) {
1278 atomic_inc(¤t
->signal
->count
);
1279 atomic_inc(¤t
->signal
->live
);
1280 p
->group_leader
= current
->group_leader
;
1281 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1284 if (likely(p
->pid
)) {
1285 tracehook_finish_clone(p
, clone_flags
, trace
);
1287 if (thread_group_leader(p
)) {
1288 if (clone_flags
& CLONE_NEWPID
)
1289 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1291 p
->signal
->leader_pid
= pid
;
1292 tty_kref_put(p
->signal
->tty
);
1293 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1294 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1295 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1296 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1297 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1298 __get_cpu_var(process_counts
)++;
1300 attach_pid(p
, PIDTYPE_PID
, pid
);
1305 spin_unlock(¤t
->sighand
->siglock
);
1306 write_unlock_irq(&tasklist_lock
);
1307 proc_fork_connector(p
);
1308 cgroup_post_fork(p
);
1313 if (pid
!= &init_struct_pid
)
1315 bad_fork_cleanup_io
:
1318 bad_fork_cleanup_namespaces
:
1319 exit_task_namespaces(p
);
1320 bad_fork_cleanup_mm
:
1323 bad_fork_cleanup_signal
:
1324 if (!(clone_flags
& CLONE_THREAD
))
1325 __cleanup_signal(p
->signal
);
1326 bad_fork_cleanup_sighand
:
1327 __cleanup_sighand(p
->sighand
);
1328 bad_fork_cleanup_fs
:
1329 exit_fs(p
); /* blocking */
1330 bad_fork_cleanup_files
:
1331 exit_files(p
); /* blocking */
1332 bad_fork_cleanup_semundo
:
1334 bad_fork_cleanup_audit
:
1336 bad_fork_cleanup_policy
:
1337 perf_event_free_task(p
);
1339 mpol_put(p
->mempolicy
);
1340 bad_fork_cleanup_cgroup
:
1342 cgroup_exit(p
, cgroup_callbacks_done
);
1343 delayacct_tsk_free(p
);
1344 module_put(task_thread_info(p
)->exec_domain
->module
);
1345 bad_fork_cleanup_count
:
1346 atomic_dec(&p
->cred
->user
->processes
);
1351 return ERR_PTR(retval
);
1354 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1356 memset(regs
, 0, sizeof(struct pt_regs
));
1360 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1362 struct task_struct
*task
;
1363 struct pt_regs regs
;
1365 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1366 &init_struct_pid
, 0);
1368 init_idle(task
, cpu
);
1374 * Ok, this is the main fork-routine.
1376 * It copies the process, and if successful kick-starts
1377 * it and waits for it to finish using the VM if required.
1379 long do_fork(unsigned long clone_flags
,
1380 unsigned long stack_start
,
1381 struct pt_regs
*regs
,
1382 unsigned long stack_size
,
1383 int __user
*parent_tidptr
,
1384 int __user
*child_tidptr
)
1386 struct task_struct
*p
;
1391 * Do some preliminary argument and permissions checking before we
1392 * actually start allocating stuff
1394 if (clone_flags
& CLONE_NEWUSER
) {
1395 if (clone_flags
& CLONE_THREAD
)
1397 /* hopefully this check will go away when userns support is
1400 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1401 !capable(CAP_SETGID
))
1406 * We hope to recycle these flags after 2.6.26
1408 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1409 static int __read_mostly count
= 100;
1411 if (count
> 0 && printk_ratelimit()) {
1412 char comm
[TASK_COMM_LEN
];
1415 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1416 "clone flags 0x%lx\n",
1417 get_task_comm(comm
, current
),
1418 clone_flags
& CLONE_STOPPED
);
1423 * When called from kernel_thread, don't do user tracing stuff.
1425 if (likely(user_mode(regs
)))
1426 trace
= tracehook_prepare_clone(clone_flags
);
1428 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1429 child_tidptr
, NULL
, trace
);
1431 * Do this prior waking up the new thread - the thread pointer
1432 * might get invalid after that point, if the thread exits quickly.
1435 struct completion vfork
;
1437 trace_sched_process_fork(current
, p
);
1439 nr
= task_pid_vnr(p
);
1441 if (clone_flags
& CLONE_PARENT_SETTID
)
1442 put_user(nr
, parent_tidptr
);
1444 if (clone_flags
& CLONE_VFORK
) {
1445 p
->vfork_done
= &vfork
;
1446 init_completion(&vfork
);
1449 audit_finish_fork(p
);
1450 tracehook_report_clone(regs
, clone_flags
, nr
, p
);
1453 * We set PF_STARTING at creation in case tracing wants to
1454 * use this to distinguish a fully live task from one that
1455 * hasn't gotten to tracehook_report_clone() yet. Now we
1456 * clear it and set the child going.
1458 p
->flags
&= ~PF_STARTING
;
1460 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1462 * We'll start up with an immediate SIGSTOP.
1464 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1465 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1466 __set_task_state(p
, TASK_STOPPED
);
1468 wake_up_new_task(p
, clone_flags
);
1471 tracehook_report_clone_complete(trace
, regs
,
1472 clone_flags
, nr
, p
);
1474 if (clone_flags
& CLONE_VFORK
) {
1475 freezer_do_not_count();
1476 wait_for_completion(&vfork
);
1478 tracehook_report_vfork_done(p
, nr
);
1486 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1487 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1490 static void sighand_ctor(void *data
)
1492 struct sighand_struct
*sighand
= data
;
1494 spin_lock_init(&sighand
->siglock
);
1495 init_waitqueue_head(&sighand
->signalfd_wqh
);
1498 void __init
proc_caches_init(void)
1500 sighand_cachep
= kmem_cache_create("sighand_cache",
1501 sizeof(struct sighand_struct
), 0,
1502 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1503 SLAB_NOTRACK
, sighand_ctor
);
1504 signal_cachep
= kmem_cache_create("signal_cache",
1505 sizeof(struct signal_struct
), 0,
1506 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1507 files_cachep
= kmem_cache_create("files_cache",
1508 sizeof(struct files_struct
), 0,
1509 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1510 fs_cachep
= kmem_cache_create("fs_cache",
1511 sizeof(struct fs_struct
), 0,
1512 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1513 mm_cachep
= kmem_cache_create("mm_struct",
1514 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1515 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1516 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1521 * Check constraints on flags passed to the unshare system call and
1522 * force unsharing of additional process context as appropriate.
1524 static void check_unshare_flags(unsigned long *flags_ptr
)
1527 * If unsharing a thread from a thread group, must also
1530 if (*flags_ptr
& CLONE_THREAD
)
1531 *flags_ptr
|= CLONE_VM
;
1534 * If unsharing vm, must also unshare signal handlers.
1536 if (*flags_ptr
& CLONE_VM
)
1537 *flags_ptr
|= CLONE_SIGHAND
;
1540 * If unsharing signal handlers and the task was created
1541 * using CLONE_THREAD, then must unshare the thread
1543 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1544 (atomic_read(¤t
->signal
->count
) > 1))
1545 *flags_ptr
|= CLONE_THREAD
;
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 write_lock(&fs
->lock
);
1698 current
->fs
= new_fs
;
1703 write_unlock(&fs
->lock
);
1708 active_mm
= current
->active_mm
;
1709 current
->mm
= new_mm
;
1710 current
->active_mm
= new_mm
;
1711 activate_mm(active_mm
, new_mm
);
1716 fd
= current
->files
;
1717 current
->files
= new_fd
;
1721 task_unlock(current
);
1725 put_nsproxy(new_nsproxy
);
1727 bad_unshare_cleanup_fd
:
1729 put_files_struct(new_fd
);
1731 bad_unshare_cleanup_vm
:
1735 bad_unshare_cleanup_sigh
:
1737 if (atomic_dec_and_test(&new_sigh
->count
))
1738 kmem_cache_free(sighand_cachep
, new_sigh
);
1740 bad_unshare_cleanup_fs
:
1742 free_fs_struct(new_fs
);
1744 bad_unshare_cleanup_thread
:
1750 * Helper to unshare the files of the current task.
1751 * We don't want to expose copy_files internals to
1752 * the exec layer of the kernel.
1755 int unshare_files(struct files_struct
**displaced
)
1757 struct task_struct
*task
= current
;
1758 struct files_struct
*copy
= NULL
;
1761 error
= unshare_fd(CLONE_FILES
, ©
);
1762 if (error
|| !copy
) {
1766 *displaced
= task
->files
;