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>
68 #include <asm/pgtable.h>
69 #include <asm/pgalloc.h>
70 #include <asm/uaccess.h>
71 #include <asm/mmu_context.h>
72 #include <asm/cacheflush.h>
73 #include <asm/tlbflush.h>
75 #include <trace/events/sched.h>
78 * Protected counters by write_lock_irq(&tasklist_lock)
80 unsigned long total_forks
; /* Handle normal Linux uptimes. */
81 int nr_threads
; /* The idle threads do not count.. */
83 int max_threads
; /* tunable limit on nr_threads */
85 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
87 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
89 int nr_processes(void)
94 for_each_possible_cpu(cpu
)
95 total
+= per_cpu(process_counts
, cpu
);
100 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
101 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
102 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
103 static struct kmem_cache
*task_struct_cachep
;
106 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
107 static inline struct thread_info
*alloc_thread_info(struct task_struct
*tsk
)
109 #ifdef CONFIG_DEBUG_STACK_USAGE
110 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
112 gfp_t mask
= GFP_KERNEL
;
114 return (struct thread_info
*)__get_free_pages(mask
, THREAD_SIZE_ORDER
);
117 static inline void free_thread_info(struct thread_info
*ti
)
119 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
123 /* SLAB cache for signal_struct structures (tsk->signal) */
124 static struct kmem_cache
*signal_cachep
;
126 /* SLAB cache for sighand_struct structures (tsk->sighand) */
127 struct kmem_cache
*sighand_cachep
;
129 /* SLAB cache for files_struct structures (tsk->files) */
130 struct kmem_cache
*files_cachep
;
132 /* SLAB cache for fs_struct structures (tsk->fs) */
133 struct kmem_cache
*fs_cachep
;
135 /* SLAB cache for vm_area_struct structures */
136 struct kmem_cache
*vm_area_cachep
;
138 /* SLAB cache for mm_struct structures (tsk->mm) */
139 static struct kmem_cache
*mm_cachep
;
141 static void account_kernel_stack(struct thread_info
*ti
, int account
)
143 struct zone
*zone
= page_zone(virt_to_page(ti
));
145 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
148 void free_task(struct task_struct
*tsk
)
150 prop_local_destroy_single(&tsk
->dirties
);
151 account_kernel_stack(tsk
->stack
, -1);
152 free_thread_info(tsk
->stack
);
153 rt_mutex_debug_task_free(tsk
);
154 ftrace_graph_exit_task(tsk
);
155 free_task_struct(tsk
);
157 EXPORT_SYMBOL(free_task
);
159 void __put_task_struct(struct task_struct
*tsk
)
161 WARN_ON(!tsk
->exit_state
);
162 WARN_ON(atomic_read(&tsk
->usage
));
163 WARN_ON(tsk
== current
);
166 delayacct_tsk_free(tsk
);
168 if (!profile_handoff_task(tsk
))
173 * macro override instead of weak attribute alias, to workaround
174 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
176 #ifndef arch_task_cache_init
177 #define arch_task_cache_init()
180 void __init
fork_init(unsigned long mempages
)
182 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
183 #ifndef ARCH_MIN_TASKALIGN
184 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
186 /* create a slab on which task_structs can be allocated */
188 kmem_cache_create("task_struct", sizeof(struct task_struct
),
189 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
192 /* do the arch specific task caches init */
193 arch_task_cache_init();
196 * The default maximum number of threads is set to a safe
197 * value: the thread structures can take up at most half
200 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
203 * we need to allow at least 20 threads to boot a system
208 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
209 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
210 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
211 init_task
.signal
->rlim
[RLIMIT_NPROC
];
214 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
215 struct task_struct
*src
)
221 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
223 struct task_struct
*tsk
;
224 struct thread_info
*ti
;
225 unsigned long *stackend
;
229 prepare_to_copy(orig
);
231 tsk
= alloc_task_struct();
235 ti
= alloc_thread_info(tsk
);
237 free_task_struct(tsk
);
241 err
= arch_dup_task_struct(tsk
, orig
);
247 err
= prop_local_init_single(&tsk
->dirties
);
251 setup_thread_stack(tsk
, orig
);
252 stackend
= end_of_stack(tsk
);
253 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
255 #ifdef CONFIG_CC_STACKPROTECTOR
256 tsk
->stack_canary
= get_random_int();
259 /* One for us, one for whoever does the "release_task()" (usually parent) */
260 atomic_set(&tsk
->usage
,2);
261 atomic_set(&tsk
->fs_excl
, 0);
262 #ifdef CONFIG_BLK_DEV_IO_TRACE
265 tsk
->splice_pipe
= NULL
;
267 account_kernel_stack(ti
, 1);
272 free_thread_info(ti
);
273 free_task_struct(tsk
);
278 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
280 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
281 struct rb_node
**rb_link
, *rb_parent
;
283 unsigned long charge
;
284 struct mempolicy
*pol
;
286 down_write(&oldmm
->mmap_sem
);
287 flush_cache_dup_mm(oldmm
);
289 * Not linked in yet - no deadlock potential:
291 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
295 mm
->mmap_cache
= NULL
;
296 mm
->free_area_cache
= oldmm
->mmap_base
;
297 mm
->cached_hole_size
= ~0UL;
299 cpumask_clear(mm_cpumask(mm
));
301 rb_link
= &mm
->mm_rb
.rb_node
;
304 retval
= ksm_fork(mm
, oldmm
);
309 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
312 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
313 long pages
= vma_pages(mpnt
);
314 mm
->total_vm
-= pages
;
315 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
320 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
321 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
322 if (security_vm_enough_memory(len
))
326 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
330 pol
= mpol_dup(vma_policy(mpnt
));
331 retval
= PTR_ERR(pol
);
333 goto fail_nomem_policy
;
334 vma_set_policy(tmp
, pol
);
335 tmp
->vm_flags
&= ~VM_LOCKED
;
337 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
341 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
342 struct address_space
*mapping
= file
->f_mapping
;
345 if (tmp
->vm_flags
& VM_DENYWRITE
)
346 atomic_dec(&inode
->i_writecount
);
347 spin_lock(&mapping
->i_mmap_lock
);
348 if (tmp
->vm_flags
& VM_SHARED
)
349 mapping
->i_mmap_writable
++;
350 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
351 flush_dcache_mmap_lock(mapping
);
352 /* insert tmp into the share list, just after mpnt */
353 vma_prio_tree_add(tmp
, mpnt
);
354 flush_dcache_mmap_unlock(mapping
);
355 spin_unlock(&mapping
->i_mmap_lock
);
359 * Clear hugetlb-related page reserves for children. This only
360 * affects MAP_PRIVATE mappings. Faults generated by the child
361 * are not guaranteed to succeed, even if read-only
363 if (is_vm_hugetlb_page(tmp
))
364 reset_vma_resv_huge_pages(tmp
);
367 * Link in the new vma and copy the page table entries.
370 pprev
= &tmp
->vm_next
;
374 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
375 rb_link
= &tmp
->vm_rb
.rb_right
;
376 rb_parent
= &tmp
->vm_rb
;
379 retval
= copy_page_range(mm
, oldmm
, mpnt
);
381 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
382 tmp
->vm_ops
->open(tmp
);
387 /* a new mm has just been created */
388 arch_dup_mmap(oldmm
, mm
);
391 up_write(&mm
->mmap_sem
);
393 up_write(&oldmm
->mmap_sem
);
396 kmem_cache_free(vm_area_cachep
, tmp
);
399 vm_unacct_memory(charge
);
403 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
405 mm
->pgd
= pgd_alloc(mm
);
406 if (unlikely(!mm
->pgd
))
411 static inline void mm_free_pgd(struct mm_struct
* mm
)
413 pgd_free(mm
, mm
->pgd
);
416 #define dup_mmap(mm, oldmm) (0)
417 #define mm_alloc_pgd(mm) (0)
418 #define mm_free_pgd(mm)
419 #endif /* CONFIG_MMU */
421 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
423 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
424 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
426 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
428 static int __init
coredump_filter_setup(char *s
)
430 default_dump_filter
=
431 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
432 MMF_DUMP_FILTER_MASK
;
436 __setup("coredump_filter=", coredump_filter_setup
);
438 #include <linux/init_task.h>
440 static void mm_init_aio(struct mm_struct
*mm
)
443 spin_lock_init(&mm
->ioctx_lock
);
444 INIT_HLIST_HEAD(&mm
->ioctx_list
);
448 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
450 atomic_set(&mm
->mm_users
, 1);
451 atomic_set(&mm
->mm_count
, 1);
452 init_rwsem(&mm
->mmap_sem
);
453 INIT_LIST_HEAD(&mm
->mmlist
);
454 mm
->flags
= (current
->mm
) ?
455 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
456 mm
->core_state
= NULL
;
458 set_mm_counter(mm
, file_rss
, 0);
459 set_mm_counter(mm
, anon_rss
, 0);
460 spin_lock_init(&mm
->page_table_lock
);
461 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
462 mm
->cached_hole_size
= ~0UL;
464 mm_init_owner(mm
, p
);
466 if (likely(!mm_alloc_pgd(mm
))) {
468 mmu_notifier_mm_init(mm
);
477 * Allocate and initialize an mm_struct.
479 struct mm_struct
* mm_alloc(void)
481 struct mm_struct
* mm
;
485 memset(mm
, 0, sizeof(*mm
));
486 mm
= mm_init(mm
, current
);
492 * Called when the last reference to the mm
493 * is dropped: either by a lazy thread or by
494 * mmput. Free the page directory and the mm.
496 void __mmdrop(struct mm_struct
*mm
)
498 BUG_ON(mm
== &init_mm
);
501 mmu_notifier_mm_destroy(mm
);
504 EXPORT_SYMBOL_GPL(__mmdrop
);
507 * Decrement the use count and release all resources for an mm.
509 void mmput(struct mm_struct
*mm
)
513 if (atomic_dec_and_test(&mm
->mm_users
)) {
517 set_mm_exe_file(mm
, NULL
);
518 if (!list_empty(&mm
->mmlist
)) {
519 spin_lock(&mmlist_lock
);
520 list_del(&mm
->mmlist
);
521 spin_unlock(&mmlist_lock
);
525 module_put(mm
->binfmt
->module
);
529 EXPORT_SYMBOL_GPL(mmput
);
532 * get_task_mm - acquire a reference to the task's mm
534 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
535 * this kernel workthread has transiently adopted a user mm with use_mm,
536 * to do its AIO) is not set and if so returns a reference to it, after
537 * bumping up the use count. User must release the mm via mmput()
538 * after use. Typically used by /proc and ptrace.
540 struct mm_struct
*get_task_mm(struct task_struct
*task
)
542 struct mm_struct
*mm
;
547 if (task
->flags
& PF_KTHREAD
)
550 atomic_inc(&mm
->mm_users
);
555 EXPORT_SYMBOL_GPL(get_task_mm
);
557 /* Please note the differences between mmput and mm_release.
558 * mmput is called whenever we stop holding onto a mm_struct,
559 * error success whatever.
561 * mm_release is called after a mm_struct has been removed
562 * from the current process.
564 * This difference is important for error handling, when we
565 * only half set up a mm_struct for a new process and need to restore
566 * the old one. Because we mmput the new mm_struct before
567 * restoring the old one. . .
568 * Eric Biederman 10 January 1998
570 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
572 struct completion
*vfork_done
= tsk
->vfork_done
;
574 /* Get rid of any futexes when releasing the mm */
576 if (unlikely(tsk
->robust_list
)) {
577 exit_robust_list(tsk
);
578 tsk
->robust_list
= NULL
;
581 if (unlikely(tsk
->compat_robust_list
)) {
582 compat_exit_robust_list(tsk
);
583 tsk
->compat_robust_list
= NULL
;
586 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
587 exit_pi_state_list(tsk
);
590 /* Get rid of any cached register state */
591 deactivate_mm(tsk
, mm
);
593 /* notify parent sleeping on vfork() */
595 tsk
->vfork_done
= NULL
;
596 complete(vfork_done
);
600 * If we're exiting normally, clear a user-space tid field if
601 * requested. We leave this alone when dying by signal, to leave
602 * the value intact in a core dump, and to save the unnecessary
603 * trouble otherwise. Userland only wants this done for a sys_exit.
605 if (tsk
->clear_child_tid
) {
606 if (!(tsk
->flags
& PF_SIGNALED
) &&
607 atomic_read(&mm
->mm_users
) > 1) {
609 * We don't check the error code - if userspace has
610 * not set up a proper pointer then tough luck.
612 put_user(0, tsk
->clear_child_tid
);
613 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
616 tsk
->clear_child_tid
= NULL
;
621 * Allocate a new mm structure and copy contents from the
622 * mm structure of the passed in task structure.
624 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
626 struct mm_struct
*mm
, *oldmm
= current
->mm
;
636 memcpy(mm
, oldmm
, sizeof(*mm
));
638 /* Initializing for Swap token stuff */
639 mm
->token_priority
= 0;
640 mm
->last_interval
= 0;
642 if (!mm_init(mm
, tsk
))
645 if (init_new_context(tsk
, mm
))
648 dup_mm_exe_file(oldmm
, mm
);
650 err
= dup_mmap(mm
, oldmm
);
654 mm
->hiwater_rss
= get_mm_rss(mm
);
655 mm
->hiwater_vm
= mm
->total_vm
;
657 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
663 /* don't put binfmt in mmput, we haven't got module yet */
672 * If init_new_context() failed, we cannot use mmput() to free the mm
673 * because it calls destroy_context()
680 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
682 struct mm_struct
* mm
, *oldmm
;
685 tsk
->min_flt
= tsk
->maj_flt
= 0;
686 tsk
->nvcsw
= tsk
->nivcsw
= 0;
687 #ifdef CONFIG_DETECT_HUNG_TASK
688 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
692 tsk
->active_mm
= NULL
;
695 * Are we cloning a kernel thread?
697 * We need to steal a active VM for that..
703 if (clone_flags
& CLONE_VM
) {
704 atomic_inc(&oldmm
->mm_users
);
715 /* Initializing for Swap token stuff */
716 mm
->token_priority
= 0;
717 mm
->last_interval
= 0;
727 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
729 struct fs_struct
*fs
= current
->fs
;
730 if (clone_flags
& CLONE_FS
) {
731 /* tsk->fs is already what we want */
732 write_lock(&fs
->lock
);
734 write_unlock(&fs
->lock
);
738 write_unlock(&fs
->lock
);
741 tsk
->fs
= copy_fs_struct(fs
);
747 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
749 struct files_struct
*oldf
, *newf
;
753 * A background process may not have any files ...
755 oldf
= current
->files
;
759 if (clone_flags
& CLONE_FILES
) {
760 atomic_inc(&oldf
->count
);
764 newf
= dup_fd(oldf
, &error
);
774 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
777 struct io_context
*ioc
= current
->io_context
;
782 * Share io context with parent, if CLONE_IO is set
784 if (clone_flags
& CLONE_IO
) {
785 tsk
->io_context
= ioc_task_link(ioc
);
786 if (unlikely(!tsk
->io_context
))
788 } else if (ioprio_valid(ioc
->ioprio
)) {
789 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
790 if (unlikely(!tsk
->io_context
))
793 tsk
->io_context
->ioprio
= ioc
->ioprio
;
799 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
801 struct sighand_struct
*sig
;
803 if (clone_flags
& CLONE_SIGHAND
) {
804 atomic_inc(¤t
->sighand
->count
);
807 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
808 rcu_assign_pointer(tsk
->sighand
, sig
);
811 atomic_set(&sig
->count
, 1);
812 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
816 void __cleanup_sighand(struct sighand_struct
*sighand
)
818 if (atomic_dec_and_test(&sighand
->count
))
819 kmem_cache_free(sighand_cachep
, sighand
);
824 * Initialize POSIX timer handling for a thread group.
826 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
828 /* Thread group counters. */
829 thread_group_cputime_init(sig
);
831 /* Expiration times and increments. */
832 sig
->it
[CPUCLOCK_PROF
].expires
= cputime_zero
;
833 sig
->it
[CPUCLOCK_PROF
].incr
= cputime_zero
;
834 sig
->it
[CPUCLOCK_VIRT
].expires
= cputime_zero
;
835 sig
->it
[CPUCLOCK_VIRT
].incr
= cputime_zero
;
837 /* Cached expiration times. */
838 sig
->cputime_expires
.prof_exp
= cputime_zero
;
839 sig
->cputime_expires
.virt_exp
= cputime_zero
;
840 sig
->cputime_expires
.sched_exp
= 0;
842 if (sig
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
) {
843 sig
->cputime_expires
.prof_exp
=
844 secs_to_cputime(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
845 sig
->cputimer
.running
= 1;
848 /* The timer lists. */
849 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
850 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
851 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
854 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
856 struct signal_struct
*sig
;
858 if (clone_flags
& CLONE_THREAD
)
861 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
866 atomic_set(&sig
->count
, 1);
867 atomic_set(&sig
->live
, 1);
868 init_waitqueue_head(&sig
->wait_chldexit
);
870 if (clone_flags
& CLONE_NEWPID
)
871 sig
->flags
|= SIGNAL_UNKILLABLE
;
872 sig
->group_exit_code
= 0;
873 sig
->group_exit_task
= NULL
;
874 sig
->group_stop_count
= 0;
875 sig
->curr_target
= tsk
;
876 init_sigpending(&sig
->shared_pending
);
877 INIT_LIST_HEAD(&sig
->posix_timers
);
879 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
880 sig
->it_real_incr
.tv64
= 0;
881 sig
->real_timer
.function
= it_real_fn
;
883 sig
->leader
= 0; /* session leadership doesn't inherit */
884 sig
->tty_old_pgrp
= NULL
;
887 sig
->utime
= sig
->stime
= sig
->cutime
= sig
->cstime
= cputime_zero
;
888 sig
->gtime
= cputime_zero
;
889 sig
->cgtime
= cputime_zero
;
890 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
891 sig
->prev_utime
= sig
->prev_stime
= cputime_zero
;
893 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
894 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
895 sig
->inblock
= sig
->oublock
= sig
->cinblock
= sig
->coublock
= 0;
896 sig
->maxrss
= sig
->cmaxrss
= 0;
897 task_io_accounting_init(&sig
->ioac
);
898 sig
->sum_sched_runtime
= 0;
899 taskstats_tgid_init(sig
);
901 task_lock(current
->group_leader
);
902 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
903 task_unlock(current
->group_leader
);
905 posix_cpu_timers_init_group(sig
);
907 acct_init_pacct(&sig
->pacct
);
911 sig
->oom_adj
= current
->signal
->oom_adj
;
916 void __cleanup_signal(struct signal_struct
*sig
)
918 thread_group_cputime_free(sig
);
919 tty_kref_put(sig
->tty
);
920 kmem_cache_free(signal_cachep
, sig
);
923 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
925 unsigned long new_flags
= p
->flags
;
927 new_flags
&= ~PF_SUPERPRIV
;
928 new_flags
|= PF_FORKNOEXEC
;
929 new_flags
|= PF_STARTING
;
930 p
->flags
= new_flags
;
931 clear_freeze_flag(p
);
934 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
936 current
->clear_child_tid
= tidptr
;
938 return task_pid_vnr(current
);
941 static void rt_mutex_init_task(struct task_struct
*p
)
943 spin_lock_init(&p
->pi_lock
);
944 #ifdef CONFIG_RT_MUTEXES
945 plist_head_init(&p
->pi_waiters
, &p
->pi_lock
);
946 p
->pi_blocked_on
= NULL
;
950 #ifdef CONFIG_MM_OWNER
951 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
955 #endif /* CONFIG_MM_OWNER */
958 * Initialize POSIX timer handling for a single task.
960 static void posix_cpu_timers_init(struct task_struct
*tsk
)
962 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
963 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
964 tsk
->cputime_expires
.sched_exp
= 0;
965 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
966 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
967 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
971 * This creates a new process as a copy of the old one,
972 * but does not actually start it yet.
974 * It copies the registers, and all the appropriate
975 * parts of the process environment (as per the clone
976 * flags). The actual kick-off is left to the caller.
978 static struct task_struct
*copy_process(unsigned long clone_flags
,
979 unsigned long stack_start
,
980 struct pt_regs
*regs
,
981 unsigned long stack_size
,
982 int __user
*child_tidptr
,
987 struct task_struct
*p
;
988 int cgroup_callbacks_done
= 0;
990 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
991 return ERR_PTR(-EINVAL
);
994 * Thread groups must share signals as well, and detached threads
995 * can only be started up within the thread group.
997 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
998 return ERR_PTR(-EINVAL
);
1001 * Shared signal handlers imply shared VM. By way of the above,
1002 * thread groups also imply shared VM. Blocking this case allows
1003 * for various simplifications in other code.
1005 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1006 return ERR_PTR(-EINVAL
);
1009 * Siblings of global init remain as zombies on exit since they are
1010 * not reaped by their parent (swapper). To solve this and to avoid
1011 * multi-rooted process trees, prevent global and container-inits
1012 * from creating siblings.
1014 if ((clone_flags
& CLONE_PARENT
) &&
1015 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1016 return ERR_PTR(-EINVAL
);
1018 retval
= security_task_create(clone_flags
);
1023 p
= dup_task_struct(current
);
1027 ftrace_graph_init_task(p
);
1029 rt_mutex_init_task(p
);
1031 #ifdef CONFIG_PROVE_LOCKING
1032 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1033 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1036 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1037 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
1038 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1039 p
->real_cred
->user
!= INIT_USER
)
1043 retval
= copy_creds(p
, clone_flags
);
1048 * If multiple threads are within copy_process(), then this check
1049 * triggers too late. This doesn't hurt, the check is only there
1050 * to stop root fork bombs.
1053 if (nr_threads
>= max_threads
)
1054 goto bad_fork_cleanup_count
;
1056 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1057 goto bad_fork_cleanup_count
;
1060 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1061 copy_flags(clone_flags
, p
);
1062 INIT_LIST_HEAD(&p
->children
);
1063 INIT_LIST_HEAD(&p
->sibling
);
1064 rcu_copy_process(p
);
1065 p
->vfork_done
= NULL
;
1066 spin_lock_init(&p
->alloc_lock
);
1068 init_sigpending(&p
->pending
);
1070 p
->utime
= cputime_zero
;
1071 p
->stime
= cputime_zero
;
1072 p
->gtime
= cputime_zero
;
1073 p
->utimescaled
= cputime_zero
;
1074 p
->stimescaled
= cputime_zero
;
1075 p
->prev_utime
= cputime_zero
;
1076 p
->prev_stime
= cputime_zero
;
1078 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1080 task_io_accounting_init(&p
->ioac
);
1081 acct_clear_integrals(p
);
1083 posix_cpu_timers_init(p
);
1085 p
->lock_depth
= -1; /* -1 = no lock */
1086 do_posix_clock_monotonic_gettime(&p
->start_time
);
1087 p
->real_start_time
= p
->start_time
;
1088 monotonic_to_bootbased(&p
->real_start_time
);
1089 p
->io_context
= NULL
;
1090 p
->audit_context
= NULL
;
1093 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1094 if (IS_ERR(p
->mempolicy
)) {
1095 retval
= PTR_ERR(p
->mempolicy
);
1096 p
->mempolicy
= NULL
;
1097 goto bad_fork_cleanup_cgroup
;
1099 mpol_fix_fork_child_flag(p
);
1101 #ifdef CONFIG_TRACE_IRQFLAGS
1103 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1104 p
->hardirqs_enabled
= 1;
1106 p
->hardirqs_enabled
= 0;
1108 p
->hardirq_enable_ip
= 0;
1109 p
->hardirq_enable_event
= 0;
1110 p
->hardirq_disable_ip
= _THIS_IP_
;
1111 p
->hardirq_disable_event
= 0;
1112 p
->softirqs_enabled
= 1;
1113 p
->softirq_enable_ip
= _THIS_IP_
;
1114 p
->softirq_enable_event
= 0;
1115 p
->softirq_disable_ip
= 0;
1116 p
->softirq_disable_event
= 0;
1117 p
->hardirq_context
= 0;
1118 p
->softirq_context
= 0;
1120 #ifdef CONFIG_LOCKDEP
1121 p
->lockdep_depth
= 0; /* no locks held yet */
1122 p
->curr_chain_key
= 0;
1123 p
->lockdep_recursion
= 0;
1126 #ifdef CONFIG_DEBUG_MUTEXES
1127 p
->blocked_on
= NULL
; /* not blocked yet */
1132 /* Perform scheduler related setup. Assign this task to a CPU. */
1133 sched_fork(p
, clone_flags
);
1135 retval
= perf_event_init_task(p
);
1137 goto bad_fork_cleanup_policy
;
1139 if ((retval
= audit_alloc(p
)))
1140 goto bad_fork_cleanup_policy
;
1141 /* copy all the process information */
1142 if ((retval
= copy_semundo(clone_flags
, p
)))
1143 goto bad_fork_cleanup_audit
;
1144 if ((retval
= copy_files(clone_flags
, p
)))
1145 goto bad_fork_cleanup_semundo
;
1146 if ((retval
= copy_fs(clone_flags
, p
)))
1147 goto bad_fork_cleanup_files
;
1148 if ((retval
= copy_sighand(clone_flags
, p
)))
1149 goto bad_fork_cleanup_fs
;
1150 if ((retval
= copy_signal(clone_flags
, p
)))
1151 goto bad_fork_cleanup_sighand
;
1152 if ((retval
= copy_mm(clone_flags
, p
)))
1153 goto bad_fork_cleanup_signal
;
1154 if ((retval
= copy_namespaces(clone_flags
, p
)))
1155 goto bad_fork_cleanup_mm
;
1156 if ((retval
= copy_io(clone_flags
, p
)))
1157 goto bad_fork_cleanup_namespaces
;
1158 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1160 goto bad_fork_cleanup_io
;
1162 if (pid
!= &init_struct_pid
) {
1164 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1166 goto bad_fork_cleanup_io
;
1168 if (clone_flags
& CLONE_NEWPID
) {
1169 retval
= pid_ns_prepare_proc(p
->nsproxy
->pid_ns
);
1171 goto bad_fork_free_pid
;
1175 p
->pid
= pid_nr(pid
);
1177 if (clone_flags
& CLONE_THREAD
)
1178 p
->tgid
= current
->tgid
;
1180 if (current
->nsproxy
!= p
->nsproxy
) {
1181 retval
= ns_cgroup_clone(p
, pid
);
1183 goto bad_fork_free_pid
;
1186 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1188 * Clear TID on mm_release()?
1190 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1192 p
->robust_list
= NULL
;
1193 #ifdef CONFIG_COMPAT
1194 p
->compat_robust_list
= NULL
;
1196 INIT_LIST_HEAD(&p
->pi_state_list
);
1197 p
->pi_state_cache
= NULL
;
1200 * sigaltstack should be cleared when sharing the same VM
1202 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1203 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1206 * Syscall tracing should be turned off in the child regardless
1209 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1210 #ifdef TIF_SYSCALL_EMU
1211 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1213 clear_all_latency_tracing(p
);
1215 /* ok, now we should be set up.. */
1216 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1217 p
->pdeath_signal
= 0;
1221 * Ok, make it visible to the rest of the system.
1222 * We dont wake it up yet.
1224 p
->group_leader
= p
;
1225 INIT_LIST_HEAD(&p
->thread_group
);
1227 /* Now that the task is set up, run cgroup callbacks if
1228 * necessary. We need to run them before the task is visible
1229 * on the tasklist. */
1230 cgroup_fork_callbacks(p
);
1231 cgroup_callbacks_done
= 1;
1233 /* Need tasklist lock for parent etc handling! */
1234 write_lock_irq(&tasklist_lock
);
1236 /* CLONE_PARENT re-uses the old parent */
1237 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1238 p
->real_parent
= current
->real_parent
;
1239 p
->parent_exec_id
= current
->parent_exec_id
;
1241 p
->real_parent
= current
;
1242 p
->parent_exec_id
= current
->self_exec_id
;
1245 spin_lock(¤t
->sighand
->siglock
);
1248 * Process group and session signals need to be delivered to just the
1249 * parent before the fork or both the parent and the child after the
1250 * fork. Restart if a signal comes in before we add the new process to
1251 * it's process group.
1252 * A fatal signal pending means that current will exit, so the new
1253 * thread can't slip out of an OOM kill (or normal SIGKILL).
1255 recalc_sigpending();
1256 if (signal_pending(current
)) {
1257 spin_unlock(¤t
->sighand
->siglock
);
1258 write_unlock_irq(&tasklist_lock
);
1259 retval
= -ERESTARTNOINTR
;
1260 goto bad_fork_free_pid
;
1263 if (clone_flags
& CLONE_THREAD
) {
1264 atomic_inc(¤t
->signal
->count
);
1265 atomic_inc(¤t
->signal
->live
);
1266 p
->group_leader
= current
->group_leader
;
1267 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1270 if (likely(p
->pid
)) {
1271 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1272 tracehook_finish_clone(p
, clone_flags
, trace
);
1274 if (thread_group_leader(p
)) {
1275 if (clone_flags
& CLONE_NEWPID
)
1276 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1278 p
->signal
->leader_pid
= pid
;
1279 tty_kref_put(p
->signal
->tty
);
1280 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1281 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1282 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1283 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1284 __get_cpu_var(process_counts
)++;
1286 attach_pid(p
, PIDTYPE_PID
, pid
);
1291 spin_unlock(¤t
->sighand
->siglock
);
1292 write_unlock_irq(&tasklist_lock
);
1293 proc_fork_connector(p
);
1294 cgroup_post_fork(p
);
1299 if (pid
!= &init_struct_pid
)
1301 bad_fork_cleanup_io
:
1302 put_io_context(p
->io_context
);
1303 bad_fork_cleanup_namespaces
:
1304 exit_task_namespaces(p
);
1305 bad_fork_cleanup_mm
:
1308 bad_fork_cleanup_signal
:
1309 if (!(clone_flags
& CLONE_THREAD
))
1310 __cleanup_signal(p
->signal
);
1311 bad_fork_cleanup_sighand
:
1312 __cleanup_sighand(p
->sighand
);
1313 bad_fork_cleanup_fs
:
1314 exit_fs(p
); /* blocking */
1315 bad_fork_cleanup_files
:
1316 exit_files(p
); /* blocking */
1317 bad_fork_cleanup_semundo
:
1319 bad_fork_cleanup_audit
:
1321 bad_fork_cleanup_policy
:
1322 perf_event_free_task(p
);
1324 mpol_put(p
->mempolicy
);
1325 bad_fork_cleanup_cgroup
:
1327 cgroup_exit(p
, cgroup_callbacks_done
);
1328 delayacct_tsk_free(p
);
1329 module_put(task_thread_info(p
)->exec_domain
->module
);
1330 bad_fork_cleanup_count
:
1331 atomic_dec(&p
->cred
->user
->processes
);
1336 return ERR_PTR(retval
);
1339 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1341 memset(regs
, 0, sizeof(struct pt_regs
));
1345 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1347 struct task_struct
*task
;
1348 struct pt_regs regs
;
1350 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1351 &init_struct_pid
, 0);
1353 init_idle(task
, cpu
);
1359 * Ok, this is the main fork-routine.
1361 * It copies the process, and if successful kick-starts
1362 * it and waits for it to finish using the VM if required.
1364 long do_fork(unsigned long clone_flags
,
1365 unsigned long stack_start
,
1366 struct pt_regs
*regs
,
1367 unsigned long stack_size
,
1368 int __user
*parent_tidptr
,
1369 int __user
*child_tidptr
)
1371 struct task_struct
*p
;
1376 * Do some preliminary argument and permissions checking before we
1377 * actually start allocating stuff
1379 if (clone_flags
& CLONE_NEWUSER
) {
1380 if (clone_flags
& CLONE_THREAD
)
1382 /* hopefully this check will go away when userns support is
1385 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1386 !capable(CAP_SETGID
))
1391 * We hope to recycle these flags after 2.6.26
1393 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1394 static int __read_mostly count
= 100;
1396 if (count
> 0 && printk_ratelimit()) {
1397 char comm
[TASK_COMM_LEN
];
1400 printk(KERN_INFO
"fork(): process `%s' used deprecated "
1401 "clone flags 0x%lx\n",
1402 get_task_comm(comm
, current
),
1403 clone_flags
& CLONE_STOPPED
);
1408 * When called from kernel_thread, don't do user tracing stuff.
1410 if (likely(user_mode(regs
)))
1411 trace
= tracehook_prepare_clone(clone_flags
);
1413 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1414 child_tidptr
, NULL
, trace
);
1416 * Do this prior waking up the new thread - the thread pointer
1417 * might get invalid after that point, if the thread exits quickly.
1420 struct completion vfork
;
1422 trace_sched_process_fork(current
, p
);
1424 nr
= task_pid_vnr(p
);
1426 if (clone_flags
& CLONE_PARENT_SETTID
)
1427 put_user(nr
, parent_tidptr
);
1429 if (clone_flags
& CLONE_VFORK
) {
1430 p
->vfork_done
= &vfork
;
1431 init_completion(&vfork
);
1434 audit_finish_fork(p
);
1435 tracehook_report_clone(regs
, clone_flags
, nr
, p
);
1438 * We set PF_STARTING at creation in case tracing wants to
1439 * use this to distinguish a fully live task from one that
1440 * hasn't gotten to tracehook_report_clone() yet. Now we
1441 * clear it and set the child going.
1443 p
->flags
&= ~PF_STARTING
;
1445 if (unlikely(clone_flags
& CLONE_STOPPED
)) {
1447 * We'll start up with an immediate SIGSTOP.
1449 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1450 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1451 __set_task_state(p
, TASK_STOPPED
);
1453 wake_up_new_task(p
, clone_flags
);
1456 tracehook_report_clone_complete(trace
, regs
,
1457 clone_flags
, nr
, p
);
1459 if (clone_flags
& CLONE_VFORK
) {
1460 freezer_do_not_count();
1461 wait_for_completion(&vfork
);
1463 tracehook_report_vfork_done(p
, nr
);
1471 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1472 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1475 static void sighand_ctor(void *data
)
1477 struct sighand_struct
*sighand
= data
;
1479 spin_lock_init(&sighand
->siglock
);
1480 init_waitqueue_head(&sighand
->signalfd_wqh
);
1483 void __init
proc_caches_init(void)
1485 sighand_cachep
= kmem_cache_create("sighand_cache",
1486 sizeof(struct sighand_struct
), 0,
1487 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1488 SLAB_NOTRACK
, sighand_ctor
);
1489 signal_cachep
= kmem_cache_create("signal_cache",
1490 sizeof(struct signal_struct
), 0,
1491 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1492 files_cachep
= kmem_cache_create("files_cache",
1493 sizeof(struct files_struct
), 0,
1494 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1495 fs_cachep
= kmem_cache_create("fs_cache",
1496 sizeof(struct fs_struct
), 0,
1497 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1498 mm_cachep
= kmem_cache_create("mm_struct",
1499 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1500 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1501 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1506 * Check constraints on flags passed to the unshare system call and
1507 * force unsharing of additional process context as appropriate.
1509 static void check_unshare_flags(unsigned long *flags_ptr
)
1512 * If unsharing a thread from a thread group, must also
1515 if (*flags_ptr
& CLONE_THREAD
)
1516 *flags_ptr
|= CLONE_VM
;
1519 * If unsharing vm, must also unshare signal handlers.
1521 if (*flags_ptr
& CLONE_VM
)
1522 *flags_ptr
|= CLONE_SIGHAND
;
1525 * If unsharing signal handlers and the task was created
1526 * using CLONE_THREAD, then must unshare the thread
1528 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1529 (atomic_read(¤t
->signal
->count
) > 1))
1530 *flags_ptr
|= CLONE_THREAD
;
1533 * If unsharing namespace, must also unshare filesystem information.
1535 if (*flags_ptr
& CLONE_NEWNS
)
1536 *flags_ptr
|= CLONE_FS
;
1540 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1542 static int unshare_thread(unsigned long unshare_flags
)
1544 if (unshare_flags
& CLONE_THREAD
)
1551 * Unshare the filesystem structure if it is being shared
1553 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1555 struct fs_struct
*fs
= current
->fs
;
1557 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1560 /* don't need lock here; in the worst case we'll do useless copy */
1564 *new_fsp
= copy_fs_struct(fs
);
1572 * Unsharing of sighand is not supported yet
1574 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1576 struct sighand_struct
*sigh
= current
->sighand
;
1578 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1585 * Unshare vm if it is being shared
1587 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1589 struct mm_struct
*mm
= current
->mm
;
1591 if ((unshare_flags
& CLONE_VM
) &&
1592 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1600 * Unshare file descriptor table if it is being shared
1602 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1604 struct files_struct
*fd
= current
->files
;
1607 if ((unshare_flags
& CLONE_FILES
) &&
1608 (fd
&& atomic_read(&fd
->count
) > 1)) {
1609 *new_fdp
= dup_fd(fd
, &error
);
1618 * unshare allows a process to 'unshare' part of the process
1619 * context which was originally shared using clone. copy_*
1620 * functions used by do_fork() cannot be used here directly
1621 * because they modify an inactive task_struct that is being
1622 * constructed. Here we are modifying the current, active,
1625 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1628 struct fs_struct
*fs
, *new_fs
= NULL
;
1629 struct sighand_struct
*new_sigh
= NULL
;
1630 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1631 struct files_struct
*fd
, *new_fd
= NULL
;
1632 struct nsproxy
*new_nsproxy
= NULL
;
1635 check_unshare_flags(&unshare_flags
);
1637 /* Return -EINVAL for all unsupported flags */
1639 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1640 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1641 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
))
1642 goto bad_unshare_out
;
1645 * CLONE_NEWIPC must also detach from the undolist: after switching
1646 * to a new ipc namespace, the semaphore arrays from the old
1647 * namespace are unreachable.
1649 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1651 if ((err
= unshare_thread(unshare_flags
)))
1652 goto bad_unshare_out
;
1653 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1654 goto bad_unshare_cleanup_thread
;
1655 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1656 goto bad_unshare_cleanup_fs
;
1657 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1658 goto bad_unshare_cleanup_sigh
;
1659 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1660 goto bad_unshare_cleanup_vm
;
1661 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1663 goto bad_unshare_cleanup_fd
;
1665 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1668 * CLONE_SYSVSEM is equivalent to sys_exit().
1674 switch_task_namespaces(current
, new_nsproxy
);
1682 write_lock(&fs
->lock
);
1683 current
->fs
= new_fs
;
1688 write_unlock(&fs
->lock
);
1693 active_mm
= current
->active_mm
;
1694 current
->mm
= new_mm
;
1695 current
->active_mm
= new_mm
;
1696 activate_mm(active_mm
, new_mm
);
1701 fd
= current
->files
;
1702 current
->files
= new_fd
;
1706 task_unlock(current
);
1710 put_nsproxy(new_nsproxy
);
1712 bad_unshare_cleanup_fd
:
1714 put_files_struct(new_fd
);
1716 bad_unshare_cleanup_vm
:
1720 bad_unshare_cleanup_sigh
:
1722 if (atomic_dec_and_test(&new_sigh
->count
))
1723 kmem_cache_free(sighand_cachep
, new_sigh
);
1725 bad_unshare_cleanup_fs
:
1727 free_fs_struct(new_fs
);
1729 bad_unshare_cleanup_thread
:
1735 * Helper to unshare the files of the current task.
1736 * We don't want to expose copy_files internals to
1737 * the exec layer of the kernel.
1740 int unshare_files(struct files_struct
**displaced
)
1742 struct task_struct
*task
= current
;
1743 struct files_struct
*copy
= NULL
;
1746 error
= unshare_fd(CLONE_FILES
, ©
);
1747 if (error
|| !copy
) {
1751 *displaced
= task
->files
;