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 sched_autogroup_exit(sig
);
173 kmem_cache_free(signal_cachep
, sig
);
176 static inline void put_signal_struct(struct signal_struct
*sig
)
178 if (atomic_dec_and_test(&sig
->sigcnt
))
179 free_signal_struct(sig
);
182 void __put_task_struct(struct task_struct
*tsk
)
184 WARN_ON(!tsk
->exit_state
);
185 WARN_ON(atomic_read(&tsk
->usage
));
186 WARN_ON(tsk
== current
);
189 delayacct_tsk_free(tsk
);
190 put_signal_struct(tsk
->signal
);
192 if (!profile_handoff_task(tsk
))
197 * macro override instead of weak attribute alias, to workaround
198 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
200 #ifndef arch_task_cache_init
201 #define arch_task_cache_init()
204 void __init
fork_init(unsigned long mempages
)
206 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
207 #ifndef ARCH_MIN_TASKALIGN
208 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
210 /* create a slab on which task_structs can be allocated */
212 kmem_cache_create("task_struct", sizeof(struct task_struct
),
213 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
216 /* do the arch specific task caches init */
217 arch_task_cache_init();
220 * The default maximum number of threads is set to a safe
221 * value: the thread structures can take up at most half
224 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
227 * we need to allow at least 20 threads to boot a system
232 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
233 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
234 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
235 init_task
.signal
->rlim
[RLIMIT_NPROC
];
238 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
239 struct task_struct
*src
)
245 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
247 struct task_struct
*tsk
;
248 struct thread_info
*ti
;
249 unsigned long *stackend
;
253 prepare_to_copy(orig
);
255 tsk
= alloc_task_struct();
259 ti
= alloc_thread_info(tsk
);
261 free_task_struct(tsk
);
265 err
= arch_dup_task_struct(tsk
, orig
);
271 err
= prop_local_init_single(&tsk
->dirties
);
275 setup_thread_stack(tsk
, orig
);
276 clear_user_return_notifier(tsk
);
277 clear_tsk_need_resched(tsk
);
278 stackend
= end_of_stack(tsk
);
279 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
281 #ifdef CONFIG_CC_STACKPROTECTOR
282 tsk
->stack_canary
= get_random_int();
285 /* One for us, one for whoever does the "release_task()" (usually parent) */
286 atomic_set(&tsk
->usage
,2);
287 atomic_set(&tsk
->fs_excl
, 0);
288 #ifdef CONFIG_BLK_DEV_IO_TRACE
291 tsk
->splice_pipe
= NULL
;
293 account_kernel_stack(ti
, 1);
298 free_thread_info(ti
);
299 free_task_struct(tsk
);
304 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
306 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
307 struct rb_node
**rb_link
, *rb_parent
;
309 unsigned long charge
;
310 struct mempolicy
*pol
;
312 down_write(&oldmm
->mmap_sem
);
313 flush_cache_dup_mm(oldmm
);
315 * Not linked in yet - no deadlock potential:
317 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
321 mm
->mmap_cache
= NULL
;
322 mm
->free_area_cache
= oldmm
->mmap_base
;
323 mm
->cached_hole_size
= ~0UL;
325 cpumask_clear(mm_cpumask(mm
));
327 rb_link
= &mm
->mm_rb
.rb_node
;
330 retval
= ksm_fork(mm
, oldmm
);
335 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
338 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
339 long pages
= vma_pages(mpnt
);
340 mm
->total_vm
-= pages
;
341 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
346 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
347 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
348 if (security_vm_enough_memory(len
))
352 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
356 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
357 pol
= mpol_dup(vma_policy(mpnt
));
358 retval
= PTR_ERR(pol
);
360 goto fail_nomem_policy
;
361 vma_set_policy(tmp
, pol
);
363 if (anon_vma_fork(tmp
, mpnt
))
364 goto fail_nomem_anon_vma_fork
;
365 tmp
->vm_flags
&= ~VM_LOCKED
;
366 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
369 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
370 struct address_space
*mapping
= file
->f_mapping
;
373 if (tmp
->vm_flags
& VM_DENYWRITE
)
374 atomic_dec(&inode
->i_writecount
);
375 spin_lock(&mapping
->i_mmap_lock
);
376 if (tmp
->vm_flags
& VM_SHARED
)
377 mapping
->i_mmap_writable
++;
378 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
379 flush_dcache_mmap_lock(mapping
);
380 /* insert tmp into the share list, just after mpnt */
381 vma_prio_tree_add(tmp
, mpnt
);
382 flush_dcache_mmap_unlock(mapping
);
383 spin_unlock(&mapping
->i_mmap_lock
);
387 * Clear hugetlb-related page reserves for children. This only
388 * affects MAP_PRIVATE mappings. Faults generated by the child
389 * are not guaranteed to succeed, even if read-only
391 if (is_vm_hugetlb_page(tmp
))
392 reset_vma_resv_huge_pages(tmp
);
395 * Link in the new vma and copy the page table entries.
398 pprev
= &tmp
->vm_next
;
402 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
403 rb_link
= &tmp
->vm_rb
.rb_right
;
404 rb_parent
= &tmp
->vm_rb
;
407 retval
= copy_page_range(mm
, oldmm
, mpnt
);
409 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
410 tmp
->vm_ops
->open(tmp
);
415 /* a new mm has just been created */
416 arch_dup_mmap(oldmm
, mm
);
419 up_write(&mm
->mmap_sem
);
421 up_write(&oldmm
->mmap_sem
);
423 fail_nomem_anon_vma_fork
:
426 kmem_cache_free(vm_area_cachep
, tmp
);
429 vm_unacct_memory(charge
);
433 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
435 mm
->pgd
= pgd_alloc(mm
);
436 if (unlikely(!mm
->pgd
))
441 static inline void mm_free_pgd(struct mm_struct
* mm
)
443 pgd_free(mm
, mm
->pgd
);
446 #define dup_mmap(mm, oldmm) (0)
447 #define mm_alloc_pgd(mm) (0)
448 #define mm_free_pgd(mm)
449 #endif /* CONFIG_MMU */
451 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
453 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
454 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
456 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
458 static int __init
coredump_filter_setup(char *s
)
460 default_dump_filter
=
461 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
462 MMF_DUMP_FILTER_MASK
;
466 __setup("coredump_filter=", coredump_filter_setup
);
468 #include <linux/init_task.h>
470 static void mm_init_aio(struct mm_struct
*mm
)
473 spin_lock_init(&mm
->ioctx_lock
);
474 INIT_HLIST_HEAD(&mm
->ioctx_list
);
478 static struct mm_struct
* mm_init(struct mm_struct
* mm
, struct task_struct
*p
)
480 atomic_set(&mm
->mm_users
, 1);
481 atomic_set(&mm
->mm_count
, 1);
482 init_rwsem(&mm
->mmap_sem
);
483 INIT_LIST_HEAD(&mm
->mmlist
);
484 mm
->flags
= (current
->mm
) ?
485 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
486 mm
->core_state
= NULL
;
488 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
489 spin_lock_init(&mm
->page_table_lock
);
490 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
491 mm
->cached_hole_size
= ~0UL;
493 mm_init_owner(mm
, p
);
494 atomic_set(&mm
->oom_disable_count
, 0);
496 if (likely(!mm_alloc_pgd(mm
))) {
498 mmu_notifier_mm_init(mm
);
507 * Allocate and initialize an mm_struct.
509 struct mm_struct
* mm_alloc(void)
511 struct mm_struct
* mm
;
515 memset(mm
, 0, sizeof(*mm
));
516 mm
= mm_init(mm
, current
);
522 * Called when the last reference to the mm
523 * is dropped: either by a lazy thread or by
524 * mmput. Free the page directory and the mm.
526 void __mmdrop(struct mm_struct
*mm
)
528 BUG_ON(mm
== &init_mm
);
531 mmu_notifier_mm_destroy(mm
);
532 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
533 VM_BUG_ON(mm
->pmd_huge_pte
);
537 EXPORT_SYMBOL_GPL(__mmdrop
);
540 * Decrement the use count and release all resources for an mm.
542 void mmput(struct mm_struct
*mm
)
546 if (atomic_dec_and_test(&mm
->mm_users
)) {
550 set_mm_exe_file(mm
, NULL
);
551 if (!list_empty(&mm
->mmlist
)) {
552 spin_lock(&mmlist_lock
);
553 list_del(&mm
->mmlist
);
554 spin_unlock(&mmlist_lock
);
558 module_put(mm
->binfmt
->module
);
562 EXPORT_SYMBOL_GPL(mmput
);
565 * get_task_mm - acquire a reference to the task's mm
567 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
568 * this kernel workthread has transiently adopted a user mm with use_mm,
569 * to do its AIO) is not set and if so returns a reference to it, after
570 * bumping up the use count. User must release the mm via mmput()
571 * after use. Typically used by /proc and ptrace.
573 struct mm_struct
*get_task_mm(struct task_struct
*task
)
575 struct mm_struct
*mm
;
580 if (task
->flags
& PF_KTHREAD
)
583 atomic_inc(&mm
->mm_users
);
588 EXPORT_SYMBOL_GPL(get_task_mm
);
590 /* Please note the differences between mmput and mm_release.
591 * mmput is called whenever we stop holding onto a mm_struct,
592 * error success whatever.
594 * mm_release is called after a mm_struct has been removed
595 * from the current process.
597 * This difference is important for error handling, when we
598 * only half set up a mm_struct for a new process and need to restore
599 * the old one. Because we mmput the new mm_struct before
600 * restoring the old one. . .
601 * Eric Biederman 10 January 1998
603 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
605 struct completion
*vfork_done
= tsk
->vfork_done
;
607 /* Get rid of any futexes when releasing the mm */
609 if (unlikely(tsk
->robust_list
)) {
610 exit_robust_list(tsk
);
611 tsk
->robust_list
= NULL
;
614 if (unlikely(tsk
->compat_robust_list
)) {
615 compat_exit_robust_list(tsk
);
616 tsk
->compat_robust_list
= NULL
;
619 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
620 exit_pi_state_list(tsk
);
623 /* Get rid of any cached register state */
624 deactivate_mm(tsk
, mm
);
626 /* notify parent sleeping on vfork() */
628 tsk
->vfork_done
= NULL
;
629 complete(vfork_done
);
633 * If we're exiting normally, clear a user-space tid field if
634 * requested. We leave this alone when dying by signal, to leave
635 * the value intact in a core dump, and to save the unnecessary
636 * trouble otherwise. Userland only wants this done for a sys_exit.
638 if (tsk
->clear_child_tid
) {
639 if (!(tsk
->flags
& PF_SIGNALED
) &&
640 atomic_read(&mm
->mm_users
) > 1) {
642 * We don't check the error code - if userspace has
643 * not set up a proper pointer then tough luck.
645 put_user(0, tsk
->clear_child_tid
);
646 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
649 tsk
->clear_child_tid
= NULL
;
654 * Allocate a new mm structure and copy contents from the
655 * mm structure of the passed in task structure.
657 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
659 struct mm_struct
*mm
, *oldmm
= current
->mm
;
669 memcpy(mm
, oldmm
, sizeof(*mm
));
671 /* Initializing for Swap token stuff */
672 mm
->token_priority
= 0;
673 mm
->last_interval
= 0;
675 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
676 mm
->pmd_huge_pte
= NULL
;
679 if (!mm_init(mm
, tsk
))
682 if (init_new_context(tsk
, mm
))
685 dup_mm_exe_file(oldmm
, mm
);
687 err
= dup_mmap(mm
, oldmm
);
691 mm
->hiwater_rss
= get_mm_rss(mm
);
692 mm
->hiwater_vm
= mm
->total_vm
;
694 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
700 /* don't put binfmt in mmput, we haven't got module yet */
709 * If init_new_context() failed, we cannot use mmput() to free the mm
710 * because it calls destroy_context()
717 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
719 struct mm_struct
* mm
, *oldmm
;
722 tsk
->min_flt
= tsk
->maj_flt
= 0;
723 tsk
->nvcsw
= tsk
->nivcsw
= 0;
724 #ifdef CONFIG_DETECT_HUNG_TASK
725 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
729 tsk
->active_mm
= NULL
;
732 * Are we cloning a kernel thread?
734 * We need to steal a active VM for that..
740 if (clone_flags
& CLONE_VM
) {
741 atomic_inc(&oldmm
->mm_users
);
752 /* Initializing for Swap token stuff */
753 mm
->token_priority
= 0;
754 mm
->last_interval
= 0;
755 if (tsk
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
)
756 atomic_inc(&mm
->oom_disable_count
);
766 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
768 struct fs_struct
*fs
= current
->fs
;
769 if (clone_flags
& CLONE_FS
) {
770 /* tsk->fs is already what we want */
771 spin_lock(&fs
->lock
);
773 spin_unlock(&fs
->lock
);
777 spin_unlock(&fs
->lock
);
780 tsk
->fs
= copy_fs_struct(fs
);
786 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
788 struct files_struct
*oldf
, *newf
;
792 * A background process may not have any files ...
794 oldf
= current
->files
;
798 if (clone_flags
& CLONE_FILES
) {
799 atomic_inc(&oldf
->count
);
803 newf
= dup_fd(oldf
, &error
);
813 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
816 struct io_context
*ioc
= current
->io_context
;
821 * Share io context with parent, if CLONE_IO is set
823 if (clone_flags
& CLONE_IO
) {
824 tsk
->io_context
= ioc_task_link(ioc
);
825 if (unlikely(!tsk
->io_context
))
827 } else if (ioprio_valid(ioc
->ioprio
)) {
828 tsk
->io_context
= alloc_io_context(GFP_KERNEL
, -1);
829 if (unlikely(!tsk
->io_context
))
832 tsk
->io_context
->ioprio
= ioc
->ioprio
;
838 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
840 struct sighand_struct
*sig
;
842 if (clone_flags
& CLONE_SIGHAND
) {
843 atomic_inc(¤t
->sighand
->count
);
846 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
847 rcu_assign_pointer(tsk
->sighand
, sig
);
850 atomic_set(&sig
->count
, 1);
851 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
855 void __cleanup_sighand(struct sighand_struct
*sighand
)
857 if (atomic_dec_and_test(&sighand
->count
))
858 kmem_cache_free(sighand_cachep
, sighand
);
863 * Initialize POSIX timer handling for a thread group.
865 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
867 unsigned long cpu_limit
;
869 /* Thread group counters. */
870 thread_group_cputime_init(sig
);
872 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
873 if (cpu_limit
!= RLIM_INFINITY
) {
874 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
875 sig
->cputimer
.running
= 1;
878 /* The timer lists. */
879 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
880 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
881 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
884 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
886 struct signal_struct
*sig
;
888 if (clone_flags
& CLONE_THREAD
)
891 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
897 atomic_set(&sig
->live
, 1);
898 atomic_set(&sig
->sigcnt
, 1);
899 init_waitqueue_head(&sig
->wait_chldexit
);
900 if (clone_flags
& CLONE_NEWPID
)
901 sig
->flags
|= SIGNAL_UNKILLABLE
;
902 sig
->curr_target
= tsk
;
903 init_sigpending(&sig
->shared_pending
);
904 INIT_LIST_HEAD(&sig
->posix_timers
);
906 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
907 sig
->real_timer
.function
= it_real_fn
;
909 task_lock(current
->group_leader
);
910 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
911 task_unlock(current
->group_leader
);
913 posix_cpu_timers_init_group(sig
);
916 sched_autogroup_fork(sig
);
918 sig
->oom_adj
= current
->signal
->oom_adj
;
919 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
920 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
922 mutex_init(&sig
->cred_guard_mutex
);
927 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
929 unsigned long new_flags
= p
->flags
;
931 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
932 new_flags
|= PF_FORKNOEXEC
;
933 new_flags
|= PF_STARTING
;
934 p
->flags
= new_flags
;
935 clear_freeze_flag(p
);
938 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
940 current
->clear_child_tid
= tidptr
;
942 return task_pid_vnr(current
);
945 static void rt_mutex_init_task(struct task_struct
*p
)
947 raw_spin_lock_init(&p
->pi_lock
);
948 #ifdef CONFIG_RT_MUTEXES
949 plist_head_init_raw(&p
->pi_waiters
, &p
->pi_lock
);
950 p
->pi_blocked_on
= NULL
;
954 #ifdef CONFIG_MM_OWNER
955 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
959 #endif /* CONFIG_MM_OWNER */
962 * Initialize POSIX timer handling for a single task.
964 static void posix_cpu_timers_init(struct task_struct
*tsk
)
966 tsk
->cputime_expires
.prof_exp
= cputime_zero
;
967 tsk
->cputime_expires
.virt_exp
= cputime_zero
;
968 tsk
->cputime_expires
.sched_exp
= 0;
969 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
970 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
971 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
975 * This creates a new process as a copy of the old one,
976 * but does not actually start it yet.
978 * It copies the registers, and all the appropriate
979 * parts of the process environment (as per the clone
980 * flags). The actual kick-off is left to the caller.
982 static struct task_struct
*copy_process(unsigned long clone_flags
,
983 unsigned long stack_start
,
984 struct pt_regs
*regs
,
985 unsigned long stack_size
,
986 int __user
*child_tidptr
,
991 struct task_struct
*p
;
992 int cgroup_callbacks_done
= 0;
994 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
995 return ERR_PTR(-EINVAL
);
998 * Thread groups must share signals as well, and detached threads
999 * can only be started up within the thread group.
1001 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1002 return ERR_PTR(-EINVAL
);
1005 * Shared signal handlers imply shared VM. By way of the above,
1006 * thread groups also imply shared VM. Blocking this case allows
1007 * for various simplifications in other code.
1009 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1010 return ERR_PTR(-EINVAL
);
1013 * Siblings of global init remain as zombies on exit since they are
1014 * not reaped by their parent (swapper). To solve this and to avoid
1015 * multi-rooted process trees, prevent global and container-inits
1016 * from creating siblings.
1018 if ((clone_flags
& CLONE_PARENT
) &&
1019 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1020 return ERR_PTR(-EINVAL
);
1022 retval
= security_task_create(clone_flags
);
1027 p
= dup_task_struct(current
);
1031 ftrace_graph_init_task(p
);
1033 rt_mutex_init_task(p
);
1035 #ifdef CONFIG_PROVE_LOCKING
1036 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1037 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1040 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1041 task_rlimit(p
, RLIMIT_NPROC
)) {
1042 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1043 p
->real_cred
->user
!= INIT_USER
)
1047 retval
= copy_creds(p
, clone_flags
);
1052 * If multiple threads are within copy_process(), then this check
1053 * triggers too late. This doesn't hurt, the check is only there
1054 * to stop root fork bombs.
1057 if (nr_threads
>= max_threads
)
1058 goto bad_fork_cleanup_count
;
1060 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1061 goto bad_fork_cleanup_count
;
1064 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1065 copy_flags(clone_flags
, p
);
1066 INIT_LIST_HEAD(&p
->children
);
1067 INIT_LIST_HEAD(&p
->sibling
);
1068 rcu_copy_process(p
);
1069 p
->vfork_done
= NULL
;
1070 spin_lock_init(&p
->alloc_lock
);
1072 init_sigpending(&p
->pending
);
1074 p
->utime
= cputime_zero
;
1075 p
->stime
= cputime_zero
;
1076 p
->gtime
= cputime_zero
;
1077 p
->utimescaled
= cputime_zero
;
1078 p
->stimescaled
= cputime_zero
;
1079 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1080 p
->prev_utime
= cputime_zero
;
1081 p
->prev_stime
= cputime_zero
;
1083 #if defined(SPLIT_RSS_COUNTING)
1084 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1087 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1089 task_io_accounting_init(&p
->ioac
);
1090 acct_clear_integrals(p
);
1092 posix_cpu_timers_init(p
);
1094 p
->lock_depth
= -1; /* -1 = no lock */
1095 do_posix_clock_monotonic_gettime(&p
->start_time
);
1096 p
->real_start_time
= p
->start_time
;
1097 monotonic_to_bootbased(&p
->real_start_time
);
1098 p
->io_context
= NULL
;
1099 p
->audit_context
= NULL
;
1102 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1103 if (IS_ERR(p
->mempolicy
)) {
1104 retval
= PTR_ERR(p
->mempolicy
);
1105 p
->mempolicy
= NULL
;
1106 goto bad_fork_cleanup_cgroup
;
1108 mpol_fix_fork_child_flag(p
);
1110 #ifdef CONFIG_TRACE_IRQFLAGS
1112 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1113 p
->hardirqs_enabled
= 1;
1115 p
->hardirqs_enabled
= 0;
1117 p
->hardirq_enable_ip
= 0;
1118 p
->hardirq_enable_event
= 0;
1119 p
->hardirq_disable_ip
= _THIS_IP_
;
1120 p
->hardirq_disable_event
= 0;
1121 p
->softirqs_enabled
= 1;
1122 p
->softirq_enable_ip
= _THIS_IP_
;
1123 p
->softirq_enable_event
= 0;
1124 p
->softirq_disable_ip
= 0;
1125 p
->softirq_disable_event
= 0;
1126 p
->hardirq_context
= 0;
1127 p
->softirq_context
= 0;
1129 #ifdef CONFIG_LOCKDEP
1130 p
->lockdep_depth
= 0; /* no locks held yet */
1131 p
->curr_chain_key
= 0;
1132 p
->lockdep_recursion
= 0;
1135 #ifdef CONFIG_DEBUG_MUTEXES
1136 p
->blocked_on
= NULL
; /* not blocked yet */
1138 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1139 p
->memcg_batch
.do_batch
= 0;
1140 p
->memcg_batch
.memcg
= NULL
;
1143 /* Perform scheduler related setup. Assign this task to a CPU. */
1144 sched_fork(p
, clone_flags
);
1146 retval
= perf_event_init_task(p
);
1148 goto bad_fork_cleanup_policy
;
1150 if ((retval
= audit_alloc(p
)))
1151 goto bad_fork_cleanup_policy
;
1152 /* copy all the process information */
1153 if ((retval
= copy_semundo(clone_flags
, p
)))
1154 goto bad_fork_cleanup_audit
;
1155 if ((retval
= copy_files(clone_flags
, p
)))
1156 goto bad_fork_cleanup_semundo
;
1157 if ((retval
= copy_fs(clone_flags
, p
)))
1158 goto bad_fork_cleanup_files
;
1159 if ((retval
= copy_sighand(clone_flags
, p
)))
1160 goto bad_fork_cleanup_fs
;
1161 if ((retval
= copy_signal(clone_flags
, p
)))
1162 goto bad_fork_cleanup_sighand
;
1163 if ((retval
= copy_mm(clone_flags
, p
)))
1164 goto bad_fork_cleanup_signal
;
1165 if ((retval
= copy_namespaces(clone_flags
, p
)))
1166 goto bad_fork_cleanup_mm
;
1167 if ((retval
= copy_io(clone_flags
, p
)))
1168 goto bad_fork_cleanup_namespaces
;
1169 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1171 goto bad_fork_cleanup_io
;
1173 if (pid
!= &init_struct_pid
) {
1175 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1177 goto bad_fork_cleanup_io
;
1179 if (clone_flags
& CLONE_NEWPID
) {
1180 retval
= pid_ns_prepare_proc(p
->nsproxy
->pid_ns
);
1182 goto bad_fork_free_pid
;
1186 p
->pid
= pid_nr(pid
);
1188 if (clone_flags
& CLONE_THREAD
)
1189 p
->tgid
= current
->tgid
;
1191 if (current
->nsproxy
!= p
->nsproxy
) {
1192 retval
= ns_cgroup_clone(p
, pid
);
1194 goto bad_fork_free_pid
;
1197 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1199 * Clear TID on mm_release()?
1201 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1203 p
->robust_list
= NULL
;
1204 #ifdef CONFIG_COMPAT
1205 p
->compat_robust_list
= NULL
;
1207 INIT_LIST_HEAD(&p
->pi_state_list
);
1208 p
->pi_state_cache
= NULL
;
1211 * sigaltstack should be cleared when sharing the same VM
1213 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1214 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1217 * Syscall tracing and stepping should be turned off in the
1218 * child regardless of CLONE_PTRACE.
1220 user_disable_single_step(p
);
1221 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1222 #ifdef TIF_SYSCALL_EMU
1223 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1225 clear_all_latency_tracing(p
);
1227 /* ok, now we should be set up.. */
1228 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1229 p
->pdeath_signal
= 0;
1233 * Ok, make it visible to the rest of the system.
1234 * We dont wake it up yet.
1236 p
->group_leader
= p
;
1237 INIT_LIST_HEAD(&p
->thread_group
);
1239 /* Now that the task is set up, run cgroup callbacks if
1240 * necessary. We need to run them before the task is visible
1241 * on the tasklist. */
1242 cgroup_fork_callbacks(p
);
1243 cgroup_callbacks_done
= 1;
1245 /* Need tasklist lock for parent etc handling! */
1246 write_lock_irq(&tasklist_lock
);
1248 /* CLONE_PARENT re-uses the old parent */
1249 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1250 p
->real_parent
= current
->real_parent
;
1251 p
->parent_exec_id
= current
->parent_exec_id
;
1253 p
->real_parent
= current
;
1254 p
->parent_exec_id
= current
->self_exec_id
;
1257 spin_lock(¤t
->sighand
->siglock
);
1260 * Process group and session signals need to be delivered to just the
1261 * parent before the fork or both the parent and the child after the
1262 * fork. Restart if a signal comes in before we add the new process to
1263 * it's process group.
1264 * A fatal signal pending means that current will exit, so the new
1265 * thread can't slip out of an OOM kill (or normal SIGKILL).
1267 recalc_sigpending();
1268 if (signal_pending(current
)) {
1269 spin_unlock(¤t
->sighand
->siglock
);
1270 write_unlock_irq(&tasklist_lock
);
1271 retval
= -ERESTARTNOINTR
;
1272 goto bad_fork_free_pid
;
1275 if (clone_flags
& CLONE_THREAD
) {
1276 current
->signal
->nr_threads
++;
1277 atomic_inc(¤t
->signal
->live
);
1278 atomic_inc(¤t
->signal
->sigcnt
);
1279 p
->group_leader
= current
->group_leader
;
1280 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1283 if (likely(p
->pid
)) {
1284 tracehook_finish_clone(p
, clone_flags
, trace
);
1286 if (thread_group_leader(p
)) {
1287 if (clone_flags
& CLONE_NEWPID
)
1288 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1290 p
->signal
->leader_pid
= pid
;
1291 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1292 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1293 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1294 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1295 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1296 __this_cpu_inc(process_counts
);
1298 attach_pid(p
, PIDTYPE_PID
, pid
);
1303 spin_unlock(¤t
->sighand
->siglock
);
1304 write_unlock_irq(&tasklist_lock
);
1305 proc_fork_connector(p
);
1306 cgroup_post_fork(p
);
1311 if (pid
!= &init_struct_pid
)
1313 bad_fork_cleanup_io
:
1316 bad_fork_cleanup_namespaces
:
1317 exit_task_namespaces(p
);
1318 bad_fork_cleanup_mm
:
1321 if (p
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
)
1322 atomic_dec(&p
->mm
->oom_disable_count
);
1326 bad_fork_cleanup_signal
:
1327 if (!(clone_flags
& CLONE_THREAD
))
1328 free_signal_struct(p
->signal
);
1329 bad_fork_cleanup_sighand
:
1330 __cleanup_sighand(p
->sighand
);
1331 bad_fork_cleanup_fs
:
1332 exit_fs(p
); /* blocking */
1333 bad_fork_cleanup_files
:
1334 exit_files(p
); /* blocking */
1335 bad_fork_cleanup_semundo
:
1337 bad_fork_cleanup_audit
:
1339 bad_fork_cleanup_policy
:
1340 perf_event_free_task(p
);
1342 mpol_put(p
->mempolicy
);
1343 bad_fork_cleanup_cgroup
:
1345 cgroup_exit(p
, cgroup_callbacks_done
);
1346 delayacct_tsk_free(p
);
1347 module_put(task_thread_info(p
)->exec_domain
->module
);
1348 bad_fork_cleanup_count
:
1349 atomic_dec(&p
->cred
->user
->processes
);
1354 return ERR_PTR(retval
);
1357 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1359 memset(regs
, 0, sizeof(struct pt_regs
));
1363 static inline void init_idle_pids(struct pid_link
*links
)
1367 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1368 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1369 links
[type
].pid
= &init_struct_pid
;
1373 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1375 struct task_struct
*task
;
1376 struct pt_regs regs
;
1378 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1379 &init_struct_pid
, 0);
1380 if (!IS_ERR(task
)) {
1381 init_idle_pids(task
->pids
);
1382 init_idle(task
, cpu
);
1389 * Ok, this is the main fork-routine.
1391 * It copies the process, and if successful kick-starts
1392 * it and waits for it to finish using the VM if required.
1394 long do_fork(unsigned long clone_flags
,
1395 unsigned long stack_start
,
1396 struct pt_regs
*regs
,
1397 unsigned long stack_size
,
1398 int __user
*parent_tidptr
,
1399 int __user
*child_tidptr
)
1401 struct task_struct
*p
;
1406 * Do some preliminary argument and permissions checking before we
1407 * actually start allocating stuff
1409 if (clone_flags
& CLONE_NEWUSER
) {
1410 if (clone_flags
& CLONE_THREAD
)
1412 /* hopefully this check will go away when userns support is
1415 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1416 !capable(CAP_SETGID
))
1421 * When called from kernel_thread, don't do user tracing stuff.
1423 if (likely(user_mode(regs
)))
1424 trace
= tracehook_prepare_clone(clone_flags
);
1426 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1427 child_tidptr
, NULL
, trace
);
1429 * Do this prior waking up the new thread - the thread pointer
1430 * might get invalid after that point, if the thread exits quickly.
1433 struct completion vfork
;
1435 trace_sched_process_fork(current
, p
);
1437 nr
= task_pid_vnr(p
);
1439 if (clone_flags
& CLONE_PARENT_SETTID
)
1440 put_user(nr
, parent_tidptr
);
1442 if (clone_flags
& CLONE_VFORK
) {
1443 p
->vfork_done
= &vfork
;
1444 init_completion(&vfork
);
1447 audit_finish_fork(p
);
1448 tracehook_report_clone(regs
, clone_flags
, nr
, p
);
1451 * We set PF_STARTING at creation in case tracing wants to
1452 * use this to distinguish a fully live task from one that
1453 * hasn't gotten to tracehook_report_clone() yet. Now we
1454 * clear it and set the child going.
1456 p
->flags
&= ~PF_STARTING
;
1458 wake_up_new_task(p
, clone_flags
);
1460 tracehook_report_clone_complete(trace
, regs
,
1461 clone_flags
, nr
, p
);
1463 if (clone_flags
& CLONE_VFORK
) {
1464 freezer_do_not_count();
1465 wait_for_completion(&vfork
);
1467 tracehook_report_vfork_done(p
, nr
);
1475 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1476 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1479 static void sighand_ctor(void *data
)
1481 struct sighand_struct
*sighand
= data
;
1483 spin_lock_init(&sighand
->siglock
);
1484 init_waitqueue_head(&sighand
->signalfd_wqh
);
1487 void __init
proc_caches_init(void)
1489 sighand_cachep
= kmem_cache_create("sighand_cache",
1490 sizeof(struct sighand_struct
), 0,
1491 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1492 SLAB_NOTRACK
, sighand_ctor
);
1493 signal_cachep
= kmem_cache_create("signal_cache",
1494 sizeof(struct signal_struct
), 0,
1495 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1496 files_cachep
= kmem_cache_create("files_cache",
1497 sizeof(struct files_struct
), 0,
1498 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1499 fs_cachep
= kmem_cache_create("fs_cache",
1500 sizeof(struct fs_struct
), 0,
1501 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1502 mm_cachep
= kmem_cache_create("mm_struct",
1503 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1504 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1505 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1510 * Check constraints on flags passed to the unshare system call and
1511 * force unsharing of additional process context as appropriate.
1513 static void check_unshare_flags(unsigned long *flags_ptr
)
1516 * If unsharing a thread from a thread group, must also
1519 if (*flags_ptr
& CLONE_THREAD
)
1520 *flags_ptr
|= CLONE_VM
;
1523 * If unsharing vm, must also unshare signal handlers.
1525 if (*flags_ptr
& CLONE_VM
)
1526 *flags_ptr
|= CLONE_SIGHAND
;
1529 * If unsharing namespace, must also unshare filesystem information.
1531 if (*flags_ptr
& CLONE_NEWNS
)
1532 *flags_ptr
|= CLONE_FS
;
1536 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1538 static int unshare_thread(unsigned long unshare_flags
)
1540 if (unshare_flags
& CLONE_THREAD
)
1547 * Unshare the filesystem structure if it is being shared
1549 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1551 struct fs_struct
*fs
= current
->fs
;
1553 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1556 /* don't need lock here; in the worst case we'll do useless copy */
1560 *new_fsp
= copy_fs_struct(fs
);
1568 * Unsharing of sighand is not supported yet
1570 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1572 struct sighand_struct
*sigh
= current
->sighand
;
1574 if ((unshare_flags
& CLONE_SIGHAND
) && atomic_read(&sigh
->count
) > 1)
1581 * Unshare vm if it is being shared
1583 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1585 struct mm_struct
*mm
= current
->mm
;
1587 if ((unshare_flags
& CLONE_VM
) &&
1588 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1596 * Unshare file descriptor table if it is being shared
1598 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1600 struct files_struct
*fd
= current
->files
;
1603 if ((unshare_flags
& CLONE_FILES
) &&
1604 (fd
&& atomic_read(&fd
->count
) > 1)) {
1605 *new_fdp
= dup_fd(fd
, &error
);
1614 * unshare allows a process to 'unshare' part of the process
1615 * context which was originally shared using clone. copy_*
1616 * functions used by do_fork() cannot be used here directly
1617 * because they modify an inactive task_struct that is being
1618 * constructed. Here we are modifying the current, active,
1621 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1624 struct fs_struct
*fs
, *new_fs
= NULL
;
1625 struct sighand_struct
*new_sigh
= NULL
;
1626 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1627 struct files_struct
*fd
, *new_fd
= NULL
;
1628 struct nsproxy
*new_nsproxy
= NULL
;
1631 check_unshare_flags(&unshare_flags
);
1633 /* Return -EINVAL for all unsupported flags */
1635 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1636 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1637 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
))
1638 goto bad_unshare_out
;
1641 * CLONE_NEWIPC must also detach from the undolist: after switching
1642 * to a new ipc namespace, the semaphore arrays from the old
1643 * namespace are unreachable.
1645 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1647 if ((err
= unshare_thread(unshare_flags
)))
1648 goto bad_unshare_out
;
1649 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1650 goto bad_unshare_cleanup_thread
;
1651 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1652 goto bad_unshare_cleanup_fs
;
1653 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1654 goto bad_unshare_cleanup_sigh
;
1655 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1656 goto bad_unshare_cleanup_vm
;
1657 if ((err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1659 goto bad_unshare_cleanup_fd
;
1661 if (new_fs
|| new_mm
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1664 * CLONE_SYSVSEM is equivalent to sys_exit().
1670 switch_task_namespaces(current
, new_nsproxy
);
1678 spin_lock(&fs
->lock
);
1679 current
->fs
= new_fs
;
1684 spin_unlock(&fs
->lock
);
1689 active_mm
= current
->active_mm
;
1690 current
->mm
= new_mm
;
1691 current
->active_mm
= new_mm
;
1692 if (current
->signal
->oom_score_adj
== OOM_SCORE_ADJ_MIN
) {
1693 atomic_dec(&mm
->oom_disable_count
);
1694 atomic_inc(&new_mm
->oom_disable_count
);
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
;