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/seccomp.h>
38 #include <linux/swap.h>
39 #include <linux/syscalls.h>
40 #include <linux/jiffies.h>
41 #include <linux/futex.h>
42 #include <linux/compat.h>
43 #include <linux/kthread.h>
44 #include <linux/task_io_accounting_ops.h>
45 #include <linux/rcupdate.h>
46 #include <linux/ptrace.h>
47 #include <linux/mount.h>
48 #include <linux/audit.h>
49 #include <linux/memcontrol.h>
50 #include <linux/ftrace.h>
51 #include <linux/proc_fs.h>
52 #include <linux/profile.h>
53 #include <linux/rmap.h>
54 #include <linux/ksm.h>
55 #include <linux/acct.h>
56 #include <linux/tsacct_kern.h>
57 #include <linux/cn_proc.h>
58 #include <linux/freezer.h>
59 #include <linux/delayacct.h>
60 #include <linux/taskstats_kern.h>
61 #include <linux/random.h>
62 #include <linux/tty.h>
63 #include <linux/blkdev.h>
64 #include <linux/fs_struct.h>
65 #include <linux/magic.h>
66 #include <linux/perf_event.h>
67 #include <linux/posix-timers.h>
68 #include <linux/user-return-notifier.h>
69 #include <linux/oom.h>
70 #include <linux/khugepaged.h>
71 #include <linux/signalfd.h>
72 #include <linux/uprobes.h>
74 #include <asm/pgtable.h>
75 #include <asm/pgalloc.h>
76 #include <asm/uaccess.h>
77 #include <asm/mmu_context.h>
78 #include <asm/cacheflush.h>
79 #include <asm/tlbflush.h>
81 #include <trace/events/sched.h>
83 #define CREATE_TRACE_POINTS
84 #include <trace/events/task.h>
87 * Protected counters by write_lock_irq(&tasklist_lock)
89 unsigned long total_forks
; /* Handle normal Linux uptimes. */
90 int nr_threads
; /* The idle threads do not count.. */
92 int max_threads
; /* tunable limit on nr_threads */
94 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
96 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
98 #ifdef CONFIG_PROVE_RCU
99 int lockdep_tasklist_lock_is_held(void)
101 return lockdep_is_held(&tasklist_lock
);
103 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
104 #endif /* #ifdef CONFIG_PROVE_RCU */
106 int nr_processes(void)
111 for_each_possible_cpu(cpu
)
112 total
+= per_cpu(process_counts
, cpu
);
117 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
121 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
122 static struct kmem_cache
*task_struct_cachep
;
124 static inline struct task_struct
*alloc_task_struct_node(int node
)
126 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
129 static inline void free_task_struct(struct task_struct
*tsk
)
131 kmem_cache_free(task_struct_cachep
, tsk
);
135 void __weak
arch_release_thread_info(struct thread_info
*ti
)
139 #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR
142 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
143 * kmemcache based allocator.
145 # if THREAD_SIZE >= PAGE_SIZE
146 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
149 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
152 return page
? page_address(page
) : NULL
;
155 static inline void free_thread_info(struct thread_info
*ti
)
157 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
160 static struct kmem_cache
*thread_info_cache
;
162 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
165 return kmem_cache_alloc_node(thread_info_cache
, THREADINFO_GFP
, node
);
168 static void free_thread_info(struct thread_info
*ti
)
170 kmem_cache_free(thread_info_cache
, ti
);
173 void thread_info_cache_init(void)
175 thread_info_cache
= kmem_cache_create("thread_info", THREAD_SIZE
,
176 THREAD_SIZE
, 0, NULL
);
177 BUG_ON(thread_info_cache
== NULL
);
182 /* SLAB cache for signal_struct structures (tsk->signal) */
183 static struct kmem_cache
*signal_cachep
;
185 /* SLAB cache for sighand_struct structures (tsk->sighand) */
186 struct kmem_cache
*sighand_cachep
;
188 /* SLAB cache for files_struct structures (tsk->files) */
189 struct kmem_cache
*files_cachep
;
191 /* SLAB cache for fs_struct structures (tsk->fs) */
192 struct kmem_cache
*fs_cachep
;
194 /* SLAB cache for vm_area_struct structures */
195 struct kmem_cache
*vm_area_cachep
;
197 /* SLAB cache for mm_struct structures (tsk->mm) */
198 static struct kmem_cache
*mm_cachep
;
200 static void account_kernel_stack(struct thread_info
*ti
, int account
)
202 struct zone
*zone
= page_zone(virt_to_page(ti
));
204 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
207 void free_task(struct task_struct
*tsk
)
209 account_kernel_stack(tsk
->stack
, -1);
210 arch_release_thread_info(tsk
->stack
);
211 free_thread_info(tsk
->stack
);
212 rt_mutex_debug_task_free(tsk
);
213 ftrace_graph_exit_task(tsk
);
214 put_seccomp_filter(tsk
);
215 arch_release_task_struct(tsk
);
216 free_task_struct(tsk
);
218 EXPORT_SYMBOL(free_task
);
220 static inline void free_signal_struct(struct signal_struct
*sig
)
222 taskstats_tgid_free(sig
);
223 sched_autogroup_exit(sig
);
224 kmem_cache_free(signal_cachep
, sig
);
227 static inline void put_signal_struct(struct signal_struct
*sig
)
229 if (atomic_dec_and_test(&sig
->sigcnt
))
230 free_signal_struct(sig
);
233 void __put_task_struct(struct task_struct
*tsk
)
235 WARN_ON(!tsk
->exit_state
);
236 WARN_ON(atomic_read(&tsk
->usage
));
237 WARN_ON(tsk
== current
);
239 security_task_free(tsk
);
241 delayacct_tsk_free(tsk
);
242 put_signal_struct(tsk
->signal
);
244 if (!profile_handoff_task(tsk
))
247 EXPORT_SYMBOL_GPL(__put_task_struct
);
249 void __init __weak
arch_task_cache_init(void) { }
251 void __init
fork_init(unsigned long mempages
)
253 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
254 #ifndef ARCH_MIN_TASKALIGN
255 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
257 /* create a slab on which task_structs can be allocated */
259 kmem_cache_create("task_struct", sizeof(struct task_struct
),
260 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
263 /* do the arch specific task caches init */
264 arch_task_cache_init();
267 * The default maximum number of threads is set to a safe
268 * value: the thread structures can take up at most half
271 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
274 * we need to allow at least 20 threads to boot a system
276 if (max_threads
< 20)
279 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
280 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
281 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
282 init_task
.signal
->rlim
[RLIMIT_NPROC
];
285 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
286 struct task_struct
*src
)
292 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
294 struct task_struct
*tsk
;
295 struct thread_info
*ti
;
296 unsigned long *stackend
;
297 int node
= tsk_fork_get_node(orig
);
300 tsk
= alloc_task_struct_node(node
);
304 ti
= alloc_thread_info_node(tsk
, node
);
308 err
= arch_dup_task_struct(tsk
, orig
);
314 setup_thread_stack(tsk
, orig
);
315 clear_user_return_notifier(tsk
);
316 clear_tsk_need_resched(tsk
);
317 stackend
= end_of_stack(tsk
);
318 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
320 #ifdef CONFIG_CC_STACKPROTECTOR
321 tsk
->stack_canary
= get_random_int();
325 * One for us, one for whoever does the "release_task()" (usually
328 atomic_set(&tsk
->usage
, 2);
329 #ifdef CONFIG_BLK_DEV_IO_TRACE
332 tsk
->splice_pipe
= NULL
;
334 account_kernel_stack(ti
, 1);
339 free_thread_info(ti
);
341 free_task_struct(tsk
);
346 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
348 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
349 struct rb_node
**rb_link
, *rb_parent
;
351 unsigned long charge
;
352 struct mempolicy
*pol
;
354 down_write(&oldmm
->mmap_sem
);
355 flush_cache_dup_mm(oldmm
);
356 uprobe_dup_mmap(oldmm
, mm
);
358 * Not linked in yet - no deadlock potential:
360 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
364 mm
->mmap_cache
= NULL
;
365 mm
->free_area_cache
= oldmm
->mmap_base
;
366 mm
->cached_hole_size
= ~0UL;
368 cpumask_clear(mm_cpumask(mm
));
370 rb_link
= &mm
->mm_rb
.rb_node
;
373 retval
= ksm_fork(mm
, oldmm
);
376 retval
= khugepaged_fork(mm
, oldmm
);
381 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
384 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
385 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
390 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
391 unsigned long len
= vma_pages(mpnt
);
393 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
397 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
401 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
402 pol
= mpol_dup(vma_policy(mpnt
));
403 retval
= PTR_ERR(pol
);
405 goto fail_nomem_policy
;
406 vma_set_policy(tmp
, pol
);
408 if (anon_vma_fork(tmp
, mpnt
))
409 goto fail_nomem_anon_vma_fork
;
410 tmp
->vm_flags
&= ~VM_LOCKED
;
411 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
414 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
415 struct address_space
*mapping
= file
->f_mapping
;
418 if (tmp
->vm_flags
& VM_DENYWRITE
)
419 atomic_dec(&inode
->i_writecount
);
420 mutex_lock(&mapping
->i_mmap_mutex
);
421 if (tmp
->vm_flags
& VM_SHARED
)
422 mapping
->i_mmap_writable
++;
423 flush_dcache_mmap_lock(mapping
);
424 /* insert tmp into the share list, just after mpnt */
425 vma_prio_tree_add(tmp
, mpnt
);
426 flush_dcache_mmap_unlock(mapping
);
427 mutex_unlock(&mapping
->i_mmap_mutex
);
431 * Clear hugetlb-related page reserves for children. This only
432 * affects MAP_PRIVATE mappings. Faults generated by the child
433 * are not guaranteed to succeed, even if read-only
435 if (is_vm_hugetlb_page(tmp
))
436 reset_vma_resv_huge_pages(tmp
);
439 * Link in the new vma and copy the page table entries.
442 pprev
= &tmp
->vm_next
;
446 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
447 rb_link
= &tmp
->vm_rb
.rb_right
;
448 rb_parent
= &tmp
->vm_rb
;
451 retval
= copy_page_range(mm
, oldmm
, mpnt
);
453 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
454 tmp
->vm_ops
->open(tmp
);
459 /* a new mm has just been created */
460 arch_dup_mmap(oldmm
, mm
);
463 up_write(&mm
->mmap_sem
);
465 up_write(&oldmm
->mmap_sem
);
467 fail_nomem_anon_vma_fork
:
470 kmem_cache_free(vm_area_cachep
, tmp
);
473 vm_unacct_memory(charge
);
477 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
479 mm
->pgd
= pgd_alloc(mm
);
480 if (unlikely(!mm
->pgd
))
485 static inline void mm_free_pgd(struct mm_struct
*mm
)
487 pgd_free(mm
, mm
->pgd
);
490 #define dup_mmap(mm, oldmm) (0)
491 #define mm_alloc_pgd(mm) (0)
492 #define mm_free_pgd(mm)
493 #endif /* CONFIG_MMU */
495 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
497 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
498 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
500 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
502 static int __init
coredump_filter_setup(char *s
)
504 default_dump_filter
=
505 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
506 MMF_DUMP_FILTER_MASK
;
510 __setup("coredump_filter=", coredump_filter_setup
);
512 #include <linux/init_task.h>
514 static void mm_init_aio(struct mm_struct
*mm
)
517 spin_lock_init(&mm
->ioctx_lock
);
518 INIT_HLIST_HEAD(&mm
->ioctx_list
);
522 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
)
524 atomic_set(&mm
->mm_users
, 1);
525 atomic_set(&mm
->mm_count
, 1);
526 init_rwsem(&mm
->mmap_sem
);
527 INIT_LIST_HEAD(&mm
->mmlist
);
528 mm
->flags
= (current
->mm
) ?
529 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
530 mm
->core_state
= NULL
;
532 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
533 spin_lock_init(&mm
->page_table_lock
);
534 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
535 mm
->cached_hole_size
= ~0UL;
537 mm_init_owner(mm
, p
);
539 if (likely(!mm_alloc_pgd(mm
))) {
541 mmu_notifier_mm_init(mm
);
549 static void check_mm(struct mm_struct
*mm
)
553 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
554 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
557 printk(KERN_ALERT
"BUG: Bad rss-counter state "
558 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
561 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
562 VM_BUG_ON(mm
->pmd_huge_pte
);
567 * Allocate and initialize an mm_struct.
569 struct mm_struct
*mm_alloc(void)
571 struct mm_struct
*mm
;
577 memset(mm
, 0, sizeof(*mm
));
579 return mm_init(mm
, current
);
583 * Called when the last reference to the mm
584 * is dropped: either by a lazy thread or by
585 * mmput. Free the page directory and the mm.
587 void __mmdrop(struct mm_struct
*mm
)
589 BUG_ON(mm
== &init_mm
);
592 mmu_notifier_mm_destroy(mm
);
596 EXPORT_SYMBOL_GPL(__mmdrop
);
599 * Decrement the use count and release all resources for an mm.
601 void mmput(struct mm_struct
*mm
)
605 if (atomic_dec_and_test(&mm
->mm_users
)) {
606 uprobe_clear_state(mm
);
609 khugepaged_exit(mm
); /* must run before exit_mmap */
611 set_mm_exe_file(mm
, NULL
);
612 if (!list_empty(&mm
->mmlist
)) {
613 spin_lock(&mmlist_lock
);
614 list_del(&mm
->mmlist
);
615 spin_unlock(&mmlist_lock
);
618 module_put(mm
->binfmt
->module
);
622 EXPORT_SYMBOL_GPL(mmput
);
625 * We added or removed a vma mapping the executable. The vmas are only mapped
626 * during exec and are not mapped with the mmap system call.
627 * Callers must hold down_write() on the mm's mmap_sem for these
629 void added_exe_file_vma(struct mm_struct
*mm
)
631 mm
->num_exe_file_vmas
++;
634 void removed_exe_file_vma(struct mm_struct
*mm
)
636 mm
->num_exe_file_vmas
--;
637 if ((mm
->num_exe_file_vmas
== 0) && mm
->exe_file
) {
644 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
647 get_file(new_exe_file
);
650 mm
->exe_file
= new_exe_file
;
651 mm
->num_exe_file_vmas
= 0;
654 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
656 struct file
*exe_file
;
658 /* We need mmap_sem to protect against races with removal of
659 * VM_EXECUTABLE vmas */
660 down_read(&mm
->mmap_sem
);
661 exe_file
= mm
->exe_file
;
664 up_read(&mm
->mmap_sem
);
668 static void dup_mm_exe_file(struct mm_struct
*oldmm
, struct mm_struct
*newmm
)
670 /* It's safe to write the exe_file pointer without exe_file_lock because
671 * this is called during fork when the task is not yet in /proc */
672 newmm
->exe_file
= get_mm_exe_file(oldmm
);
676 * get_task_mm - acquire a reference to the task's mm
678 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
679 * this kernel workthread has transiently adopted a user mm with use_mm,
680 * to do its AIO) is not set and if so returns a reference to it, after
681 * bumping up the use count. User must release the mm via mmput()
682 * after use. Typically used by /proc and ptrace.
684 struct mm_struct
*get_task_mm(struct task_struct
*task
)
686 struct mm_struct
*mm
;
691 if (task
->flags
& PF_KTHREAD
)
694 atomic_inc(&mm
->mm_users
);
699 EXPORT_SYMBOL_GPL(get_task_mm
);
701 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
703 struct mm_struct
*mm
;
706 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
710 mm
= get_task_mm(task
);
711 if (mm
&& mm
!= current
->mm
&&
712 !ptrace_may_access(task
, mode
)) {
714 mm
= ERR_PTR(-EACCES
);
716 mutex_unlock(&task
->signal
->cred_guard_mutex
);
721 static void complete_vfork_done(struct task_struct
*tsk
)
723 struct completion
*vfork
;
726 vfork
= tsk
->vfork_done
;
728 tsk
->vfork_done
= NULL
;
734 static int wait_for_vfork_done(struct task_struct
*child
,
735 struct completion
*vfork
)
739 freezer_do_not_count();
740 killed
= wait_for_completion_killable(vfork
);
745 child
->vfork_done
= NULL
;
749 put_task_struct(child
);
753 /* Please note the differences between mmput and mm_release.
754 * mmput is called whenever we stop holding onto a mm_struct,
755 * error success whatever.
757 * mm_release is called after a mm_struct has been removed
758 * from the current process.
760 * This difference is important for error handling, when we
761 * only half set up a mm_struct for a new process and need to restore
762 * the old one. Because we mmput the new mm_struct before
763 * restoring the old one. . .
764 * Eric Biederman 10 January 1998
766 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
768 /* Get rid of any futexes when releasing the mm */
770 if (unlikely(tsk
->robust_list
)) {
771 exit_robust_list(tsk
);
772 tsk
->robust_list
= NULL
;
775 if (unlikely(tsk
->compat_robust_list
)) {
776 compat_exit_robust_list(tsk
);
777 tsk
->compat_robust_list
= NULL
;
780 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
781 exit_pi_state_list(tsk
);
784 uprobe_free_utask(tsk
);
786 /* Get rid of any cached register state */
787 deactivate_mm(tsk
, mm
);
790 * If we're exiting normally, clear a user-space tid field if
791 * requested. We leave this alone when dying by signal, to leave
792 * the value intact in a core dump, and to save the unnecessary
793 * trouble, say, a killed vfork parent shouldn't touch this mm.
794 * Userland only wants this done for a sys_exit.
796 if (tsk
->clear_child_tid
) {
797 if (!(tsk
->flags
& PF_SIGNALED
) &&
798 atomic_read(&mm
->mm_users
) > 1) {
800 * We don't check the error code - if userspace has
801 * not set up a proper pointer then tough luck.
803 put_user(0, tsk
->clear_child_tid
);
804 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
807 tsk
->clear_child_tid
= NULL
;
811 * All done, finally we can wake up parent and return this mm to him.
812 * Also kthread_stop() uses this completion for synchronization.
815 complete_vfork_done(tsk
);
819 * Allocate a new mm structure and copy contents from the
820 * mm structure of the passed in task structure.
822 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
824 struct mm_struct
*mm
, *oldmm
= current
->mm
;
834 memcpy(mm
, oldmm
, sizeof(*mm
));
837 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
838 mm
->pmd_huge_pte
= NULL
;
840 if (!mm_init(mm
, tsk
))
843 if (init_new_context(tsk
, mm
))
846 dup_mm_exe_file(oldmm
, mm
);
848 err
= dup_mmap(mm
, oldmm
);
852 mm
->hiwater_rss
= get_mm_rss(mm
);
853 mm
->hiwater_vm
= mm
->total_vm
;
855 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
861 /* don't put binfmt in mmput, we haven't got module yet */
870 * If init_new_context() failed, we cannot use mmput() to free the mm
871 * because it calls destroy_context()
878 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
880 struct mm_struct
*mm
, *oldmm
;
883 tsk
->min_flt
= tsk
->maj_flt
= 0;
884 tsk
->nvcsw
= tsk
->nivcsw
= 0;
885 #ifdef CONFIG_DETECT_HUNG_TASK
886 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
890 tsk
->active_mm
= NULL
;
893 * Are we cloning a kernel thread?
895 * We need to steal a active VM for that..
901 if (clone_flags
& CLONE_VM
) {
902 atomic_inc(&oldmm
->mm_users
);
921 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
923 struct fs_struct
*fs
= current
->fs
;
924 if (clone_flags
& CLONE_FS
) {
925 /* tsk->fs is already what we want */
926 spin_lock(&fs
->lock
);
928 spin_unlock(&fs
->lock
);
932 spin_unlock(&fs
->lock
);
935 tsk
->fs
= copy_fs_struct(fs
);
941 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
943 struct files_struct
*oldf
, *newf
;
947 * A background process may not have any files ...
949 oldf
= current
->files
;
953 if (clone_flags
& CLONE_FILES
) {
954 atomic_inc(&oldf
->count
);
958 newf
= dup_fd(oldf
, &error
);
968 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
971 struct io_context
*ioc
= current
->io_context
;
972 struct io_context
*new_ioc
;
977 * Share io context with parent, if CLONE_IO is set
979 if (clone_flags
& CLONE_IO
) {
981 tsk
->io_context
= ioc
;
982 } else if (ioprio_valid(ioc
->ioprio
)) {
983 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
984 if (unlikely(!new_ioc
))
987 new_ioc
->ioprio
= ioc
->ioprio
;
988 put_io_context(new_ioc
);
994 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
996 struct sighand_struct
*sig
;
998 if (clone_flags
& CLONE_SIGHAND
) {
999 atomic_inc(¤t
->sighand
->count
);
1002 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1003 rcu_assign_pointer(tsk
->sighand
, sig
);
1006 atomic_set(&sig
->count
, 1);
1007 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1011 void __cleanup_sighand(struct sighand_struct
*sighand
)
1013 if (atomic_dec_and_test(&sighand
->count
)) {
1014 signalfd_cleanup(sighand
);
1015 kmem_cache_free(sighand_cachep
, sighand
);
1021 * Initialize POSIX timer handling for a thread group.
1023 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1025 unsigned long cpu_limit
;
1027 /* Thread group counters. */
1028 thread_group_cputime_init(sig
);
1030 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1031 if (cpu_limit
!= RLIM_INFINITY
) {
1032 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1033 sig
->cputimer
.running
= 1;
1036 /* The timer lists. */
1037 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1038 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1039 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1042 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1044 struct signal_struct
*sig
;
1046 if (clone_flags
& CLONE_THREAD
)
1049 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1054 sig
->nr_threads
= 1;
1055 atomic_set(&sig
->live
, 1);
1056 atomic_set(&sig
->sigcnt
, 1);
1057 init_waitqueue_head(&sig
->wait_chldexit
);
1058 if (clone_flags
& CLONE_NEWPID
)
1059 sig
->flags
|= SIGNAL_UNKILLABLE
;
1060 sig
->curr_target
= tsk
;
1061 init_sigpending(&sig
->shared_pending
);
1062 INIT_LIST_HEAD(&sig
->posix_timers
);
1064 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1065 sig
->real_timer
.function
= it_real_fn
;
1067 task_lock(current
->group_leader
);
1068 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1069 task_unlock(current
->group_leader
);
1071 posix_cpu_timers_init_group(sig
);
1073 tty_audit_fork(sig
);
1074 sched_autogroup_fork(sig
);
1076 #ifdef CONFIG_CGROUPS
1077 init_rwsem(&sig
->group_rwsem
);
1080 sig
->oom_adj
= current
->signal
->oom_adj
;
1081 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1082 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1084 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1085 current
->signal
->is_child_subreaper
;
1087 mutex_init(&sig
->cred_guard_mutex
);
1092 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
1094 unsigned long new_flags
= p
->flags
;
1096 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
1097 new_flags
|= PF_FORKNOEXEC
;
1098 p
->flags
= new_flags
;
1101 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1103 current
->clear_child_tid
= tidptr
;
1105 return task_pid_vnr(current
);
1108 static void rt_mutex_init_task(struct task_struct
*p
)
1110 raw_spin_lock_init(&p
->pi_lock
);
1111 #ifdef CONFIG_RT_MUTEXES
1112 plist_head_init(&p
->pi_waiters
);
1113 p
->pi_blocked_on
= NULL
;
1117 #ifdef CONFIG_MM_OWNER
1118 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1122 #endif /* CONFIG_MM_OWNER */
1125 * Initialize POSIX timer handling for a single task.
1127 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1129 tsk
->cputime_expires
.prof_exp
= 0;
1130 tsk
->cputime_expires
.virt_exp
= 0;
1131 tsk
->cputime_expires
.sched_exp
= 0;
1132 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1133 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1134 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1138 * This creates a new process as a copy of the old one,
1139 * but does not actually start it yet.
1141 * It copies the registers, and all the appropriate
1142 * parts of the process environment (as per the clone
1143 * flags). The actual kick-off is left to the caller.
1145 static struct task_struct
*copy_process(unsigned long clone_flags
,
1146 unsigned long stack_start
,
1147 struct pt_regs
*regs
,
1148 unsigned long stack_size
,
1149 int __user
*child_tidptr
,
1154 struct task_struct
*p
;
1155 int cgroup_callbacks_done
= 0;
1157 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1158 return ERR_PTR(-EINVAL
);
1161 * Thread groups must share signals as well, and detached threads
1162 * can only be started up within the thread group.
1164 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1165 return ERR_PTR(-EINVAL
);
1168 * Shared signal handlers imply shared VM. By way of the above,
1169 * thread groups also imply shared VM. Blocking this case allows
1170 * for various simplifications in other code.
1172 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1173 return ERR_PTR(-EINVAL
);
1176 * Siblings of global init remain as zombies on exit since they are
1177 * not reaped by their parent (swapper). To solve this and to avoid
1178 * multi-rooted process trees, prevent global and container-inits
1179 * from creating siblings.
1181 if ((clone_flags
& CLONE_PARENT
) &&
1182 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1183 return ERR_PTR(-EINVAL
);
1185 retval
= security_task_create(clone_flags
);
1190 p
= dup_task_struct(current
);
1194 ftrace_graph_init_task(p
);
1195 get_seccomp_filter(p
);
1197 rt_mutex_init_task(p
);
1199 #ifdef CONFIG_PROVE_LOCKING
1200 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1201 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1204 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1205 task_rlimit(p
, RLIMIT_NPROC
)) {
1206 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1207 p
->real_cred
->user
!= INIT_USER
)
1210 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1212 retval
= copy_creds(p
, clone_flags
);
1217 * If multiple threads are within copy_process(), then this check
1218 * triggers too late. This doesn't hurt, the check is only there
1219 * to stop root fork bombs.
1222 if (nr_threads
>= max_threads
)
1223 goto bad_fork_cleanup_count
;
1225 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1226 goto bad_fork_cleanup_count
;
1229 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1230 copy_flags(clone_flags
, p
);
1231 INIT_LIST_HEAD(&p
->children
);
1232 INIT_LIST_HEAD(&p
->sibling
);
1233 rcu_copy_process(p
);
1234 p
->vfork_done
= NULL
;
1235 spin_lock_init(&p
->alloc_lock
);
1237 init_sigpending(&p
->pending
);
1239 p
->utime
= p
->stime
= p
->gtime
= 0;
1240 p
->utimescaled
= p
->stimescaled
= 0;
1241 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1242 p
->prev_utime
= p
->prev_stime
= 0;
1244 #if defined(SPLIT_RSS_COUNTING)
1245 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1248 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1250 task_io_accounting_init(&p
->ioac
);
1251 acct_clear_integrals(p
);
1253 posix_cpu_timers_init(p
);
1255 do_posix_clock_monotonic_gettime(&p
->start_time
);
1256 p
->real_start_time
= p
->start_time
;
1257 monotonic_to_bootbased(&p
->real_start_time
);
1258 p
->io_context
= NULL
;
1259 p
->audit_context
= NULL
;
1260 if (clone_flags
& CLONE_THREAD
)
1261 threadgroup_change_begin(current
);
1264 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1265 if (IS_ERR(p
->mempolicy
)) {
1266 retval
= PTR_ERR(p
->mempolicy
);
1267 p
->mempolicy
= NULL
;
1268 goto bad_fork_cleanup_cgroup
;
1270 mpol_fix_fork_child_flag(p
);
1272 #ifdef CONFIG_CPUSETS
1273 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1274 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1275 seqcount_init(&p
->mems_allowed_seq
);
1277 #ifdef CONFIG_TRACE_IRQFLAGS
1279 p
->hardirqs_enabled
= 0;
1280 p
->hardirq_enable_ip
= 0;
1281 p
->hardirq_enable_event
= 0;
1282 p
->hardirq_disable_ip
= _THIS_IP_
;
1283 p
->hardirq_disable_event
= 0;
1284 p
->softirqs_enabled
= 1;
1285 p
->softirq_enable_ip
= _THIS_IP_
;
1286 p
->softirq_enable_event
= 0;
1287 p
->softirq_disable_ip
= 0;
1288 p
->softirq_disable_event
= 0;
1289 p
->hardirq_context
= 0;
1290 p
->softirq_context
= 0;
1292 #ifdef CONFIG_LOCKDEP
1293 p
->lockdep_depth
= 0; /* no locks held yet */
1294 p
->curr_chain_key
= 0;
1295 p
->lockdep_recursion
= 0;
1298 #ifdef CONFIG_DEBUG_MUTEXES
1299 p
->blocked_on
= NULL
; /* not blocked yet */
1302 p
->memcg_batch
.do_batch
= 0;
1303 p
->memcg_batch
.memcg
= NULL
;
1306 /* Perform scheduler related setup. Assign this task to a CPU. */
1309 retval
= perf_event_init_task(p
);
1311 goto bad_fork_cleanup_policy
;
1312 retval
= audit_alloc(p
);
1314 goto bad_fork_cleanup_policy
;
1315 /* copy all the process information */
1316 retval
= copy_semundo(clone_flags
, p
);
1318 goto bad_fork_cleanup_audit
;
1319 retval
= copy_files(clone_flags
, p
);
1321 goto bad_fork_cleanup_semundo
;
1322 retval
= copy_fs(clone_flags
, p
);
1324 goto bad_fork_cleanup_files
;
1325 retval
= copy_sighand(clone_flags
, p
);
1327 goto bad_fork_cleanup_fs
;
1328 retval
= copy_signal(clone_flags
, p
);
1330 goto bad_fork_cleanup_sighand
;
1331 retval
= copy_mm(clone_flags
, p
);
1333 goto bad_fork_cleanup_signal
;
1334 retval
= copy_namespaces(clone_flags
, p
);
1336 goto bad_fork_cleanup_mm
;
1337 retval
= copy_io(clone_flags
, p
);
1339 goto bad_fork_cleanup_namespaces
;
1340 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1342 goto bad_fork_cleanup_io
;
1344 if (pid
!= &init_struct_pid
) {
1346 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1348 goto bad_fork_cleanup_io
;
1351 p
->pid
= pid_nr(pid
);
1353 if (clone_flags
& CLONE_THREAD
)
1354 p
->tgid
= current
->tgid
;
1356 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1358 * Clear TID on mm_release()?
1360 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1365 p
->robust_list
= NULL
;
1366 #ifdef CONFIG_COMPAT
1367 p
->compat_robust_list
= NULL
;
1369 INIT_LIST_HEAD(&p
->pi_state_list
);
1370 p
->pi_state_cache
= NULL
;
1372 uprobe_copy_process(p
);
1374 * sigaltstack should be cleared when sharing the same VM
1376 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1377 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1380 * Syscall tracing and stepping should be turned off in the
1381 * child regardless of CLONE_PTRACE.
1383 user_disable_single_step(p
);
1384 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1385 #ifdef TIF_SYSCALL_EMU
1386 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1388 clear_all_latency_tracing(p
);
1390 /* ok, now we should be set up.. */
1391 if (clone_flags
& CLONE_THREAD
)
1392 p
->exit_signal
= -1;
1393 else if (clone_flags
& CLONE_PARENT
)
1394 p
->exit_signal
= current
->group_leader
->exit_signal
;
1396 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1398 p
->pdeath_signal
= 0;
1402 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1403 p
->dirty_paused_when
= 0;
1406 * Ok, make it visible to the rest of the system.
1407 * We dont wake it up yet.
1409 p
->group_leader
= p
;
1410 INIT_LIST_HEAD(&p
->thread_group
);
1411 p
->task_works
= NULL
;
1413 /* Now that the task is set up, run cgroup callbacks if
1414 * necessary. We need to run them before the task is visible
1415 * on the tasklist. */
1416 cgroup_fork_callbacks(p
);
1417 cgroup_callbacks_done
= 1;
1419 /* Need tasklist lock for parent etc handling! */
1420 write_lock_irq(&tasklist_lock
);
1422 /* CLONE_PARENT re-uses the old parent */
1423 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1424 p
->real_parent
= current
->real_parent
;
1425 p
->parent_exec_id
= current
->parent_exec_id
;
1427 p
->real_parent
= current
;
1428 p
->parent_exec_id
= current
->self_exec_id
;
1431 spin_lock(¤t
->sighand
->siglock
);
1434 * Process group and session signals need to be delivered to just the
1435 * parent before the fork or both the parent and the child after the
1436 * fork. Restart if a signal comes in before we add the new process to
1437 * it's process group.
1438 * A fatal signal pending means that current will exit, so the new
1439 * thread can't slip out of an OOM kill (or normal SIGKILL).
1441 recalc_sigpending();
1442 if (signal_pending(current
)) {
1443 spin_unlock(¤t
->sighand
->siglock
);
1444 write_unlock_irq(&tasklist_lock
);
1445 retval
= -ERESTARTNOINTR
;
1446 goto bad_fork_free_pid
;
1449 if (clone_flags
& CLONE_THREAD
) {
1450 current
->signal
->nr_threads
++;
1451 atomic_inc(¤t
->signal
->live
);
1452 atomic_inc(¤t
->signal
->sigcnt
);
1453 p
->group_leader
= current
->group_leader
;
1454 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1457 if (likely(p
->pid
)) {
1458 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1460 if (thread_group_leader(p
)) {
1461 if (is_child_reaper(pid
))
1462 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1464 p
->signal
->leader_pid
= pid
;
1465 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1466 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1467 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1468 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1469 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1470 __this_cpu_inc(process_counts
);
1472 attach_pid(p
, PIDTYPE_PID
, pid
);
1477 spin_unlock(¤t
->sighand
->siglock
);
1478 write_unlock_irq(&tasklist_lock
);
1479 proc_fork_connector(p
);
1480 cgroup_post_fork(p
);
1481 if (clone_flags
& CLONE_THREAD
)
1482 threadgroup_change_end(current
);
1485 trace_task_newtask(p
, clone_flags
);
1490 if (pid
!= &init_struct_pid
)
1492 bad_fork_cleanup_io
:
1495 bad_fork_cleanup_namespaces
:
1496 if (unlikely(clone_flags
& CLONE_NEWPID
))
1497 pid_ns_release_proc(p
->nsproxy
->pid_ns
);
1498 exit_task_namespaces(p
);
1499 bad_fork_cleanup_mm
:
1502 bad_fork_cleanup_signal
:
1503 if (!(clone_flags
& CLONE_THREAD
))
1504 free_signal_struct(p
->signal
);
1505 bad_fork_cleanup_sighand
:
1506 __cleanup_sighand(p
->sighand
);
1507 bad_fork_cleanup_fs
:
1508 exit_fs(p
); /* blocking */
1509 bad_fork_cleanup_files
:
1510 exit_files(p
); /* blocking */
1511 bad_fork_cleanup_semundo
:
1513 bad_fork_cleanup_audit
:
1515 bad_fork_cleanup_policy
:
1516 perf_event_free_task(p
);
1518 mpol_put(p
->mempolicy
);
1519 bad_fork_cleanup_cgroup
:
1521 if (clone_flags
& CLONE_THREAD
)
1522 threadgroup_change_end(current
);
1523 cgroup_exit(p
, cgroup_callbacks_done
);
1524 delayacct_tsk_free(p
);
1525 module_put(task_thread_info(p
)->exec_domain
->module
);
1526 bad_fork_cleanup_count
:
1527 atomic_dec(&p
->cred
->user
->processes
);
1532 return ERR_PTR(retval
);
1535 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1537 memset(regs
, 0, sizeof(struct pt_regs
));
1541 static inline void init_idle_pids(struct pid_link
*links
)
1545 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1546 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1547 links
[type
].pid
= &init_struct_pid
;
1551 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1553 struct task_struct
*task
;
1554 struct pt_regs regs
;
1556 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1557 &init_struct_pid
, 0);
1558 if (!IS_ERR(task
)) {
1559 init_idle_pids(task
->pids
);
1560 init_idle(task
, cpu
);
1567 * Ok, this is the main fork-routine.
1569 * It copies the process, and if successful kick-starts
1570 * it and waits for it to finish using the VM if required.
1572 long do_fork(unsigned long clone_flags
,
1573 unsigned long stack_start
,
1574 struct pt_regs
*regs
,
1575 unsigned long stack_size
,
1576 int __user
*parent_tidptr
,
1577 int __user
*child_tidptr
)
1579 struct task_struct
*p
;
1584 * Do some preliminary argument and permissions checking before we
1585 * actually start allocating stuff
1587 if (clone_flags
& CLONE_NEWUSER
) {
1588 if (clone_flags
& CLONE_THREAD
)
1590 /* hopefully this check will go away when userns support is
1593 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1594 !capable(CAP_SETGID
))
1599 * Determine whether and which event to report to ptracer. When
1600 * called from kernel_thread or CLONE_UNTRACED is explicitly
1601 * requested, no event is reported; otherwise, report if the event
1602 * for the type of forking is enabled.
1604 if (likely(user_mode(regs
)) && !(clone_flags
& CLONE_UNTRACED
)) {
1605 if (clone_flags
& CLONE_VFORK
)
1606 trace
= PTRACE_EVENT_VFORK
;
1607 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1608 trace
= PTRACE_EVENT_CLONE
;
1610 trace
= PTRACE_EVENT_FORK
;
1612 if (likely(!ptrace_event_enabled(current
, trace
)))
1616 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1617 child_tidptr
, NULL
, trace
);
1619 * Do this prior waking up the new thread - the thread pointer
1620 * might get invalid after that point, if the thread exits quickly.
1623 struct completion vfork
;
1625 trace_sched_process_fork(current
, p
);
1627 nr
= task_pid_vnr(p
);
1629 if (clone_flags
& CLONE_PARENT_SETTID
)
1630 put_user(nr
, parent_tidptr
);
1632 if (clone_flags
& CLONE_VFORK
) {
1633 p
->vfork_done
= &vfork
;
1634 init_completion(&vfork
);
1638 wake_up_new_task(p
);
1640 /* forking complete and child started to run, tell ptracer */
1641 if (unlikely(trace
))
1642 ptrace_event(trace
, nr
);
1644 if (clone_flags
& CLONE_VFORK
) {
1645 if (!wait_for_vfork_done(p
, &vfork
))
1646 ptrace_event(PTRACE_EVENT_VFORK_DONE
, nr
);
1654 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1655 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1658 static void sighand_ctor(void *data
)
1660 struct sighand_struct
*sighand
= data
;
1662 spin_lock_init(&sighand
->siglock
);
1663 init_waitqueue_head(&sighand
->signalfd_wqh
);
1666 void __init
proc_caches_init(void)
1668 sighand_cachep
= kmem_cache_create("sighand_cache",
1669 sizeof(struct sighand_struct
), 0,
1670 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1671 SLAB_NOTRACK
, sighand_ctor
);
1672 signal_cachep
= kmem_cache_create("signal_cache",
1673 sizeof(struct signal_struct
), 0,
1674 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1675 files_cachep
= kmem_cache_create("files_cache",
1676 sizeof(struct files_struct
), 0,
1677 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1678 fs_cachep
= kmem_cache_create("fs_cache",
1679 sizeof(struct fs_struct
), 0,
1680 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1682 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1683 * whole struct cpumask for the OFFSTACK case. We could change
1684 * this to *only* allocate as much of it as required by the
1685 * maximum number of CPU's we can ever have. The cpumask_allocation
1686 * is at the end of the structure, exactly for that reason.
1688 mm_cachep
= kmem_cache_create("mm_struct",
1689 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1690 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1691 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1693 nsproxy_cache_init();
1697 * Check constraints on flags passed to the unshare system call.
1699 static int check_unshare_flags(unsigned long unshare_flags
)
1701 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1702 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1703 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
))
1706 * Not implemented, but pretend it works if there is nothing to
1707 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1708 * needs to unshare vm.
1710 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
1711 /* FIXME: get_task_mm() increments ->mm_users */
1712 if (atomic_read(¤t
->mm
->mm_users
) > 1)
1720 * Unshare the filesystem structure if it is being shared
1722 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1724 struct fs_struct
*fs
= current
->fs
;
1726 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1729 /* don't need lock here; in the worst case we'll do useless copy */
1733 *new_fsp
= copy_fs_struct(fs
);
1741 * Unshare file descriptor table if it is being shared
1743 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1745 struct files_struct
*fd
= current
->files
;
1748 if ((unshare_flags
& CLONE_FILES
) &&
1749 (fd
&& atomic_read(&fd
->count
) > 1)) {
1750 *new_fdp
= dup_fd(fd
, &error
);
1759 * unshare allows a process to 'unshare' part of the process
1760 * context which was originally shared using clone. copy_*
1761 * functions used by do_fork() cannot be used here directly
1762 * because they modify an inactive task_struct that is being
1763 * constructed. Here we are modifying the current, active,
1766 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1768 struct fs_struct
*fs
, *new_fs
= NULL
;
1769 struct files_struct
*fd
, *new_fd
= NULL
;
1770 struct nsproxy
*new_nsproxy
= NULL
;
1774 err
= check_unshare_flags(unshare_flags
);
1776 goto bad_unshare_out
;
1779 * If unsharing namespace, must also unshare filesystem information.
1781 if (unshare_flags
& CLONE_NEWNS
)
1782 unshare_flags
|= CLONE_FS
;
1784 * CLONE_NEWIPC must also detach from the undolist: after switching
1785 * to a new ipc namespace, the semaphore arrays from the old
1786 * namespace are unreachable.
1788 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1790 err
= unshare_fs(unshare_flags
, &new_fs
);
1792 goto bad_unshare_out
;
1793 err
= unshare_fd(unshare_flags
, &new_fd
);
1795 goto bad_unshare_cleanup_fs
;
1796 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
, new_fs
);
1798 goto bad_unshare_cleanup_fd
;
1800 if (new_fs
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1803 * CLONE_SYSVSEM is equivalent to sys_exit().
1809 switch_task_namespaces(current
, new_nsproxy
);
1817 spin_lock(&fs
->lock
);
1818 current
->fs
= new_fs
;
1823 spin_unlock(&fs
->lock
);
1827 fd
= current
->files
;
1828 current
->files
= new_fd
;
1832 task_unlock(current
);
1836 put_nsproxy(new_nsproxy
);
1838 bad_unshare_cleanup_fd
:
1840 put_files_struct(new_fd
);
1842 bad_unshare_cleanup_fs
:
1844 free_fs_struct(new_fs
);
1851 * Helper to unshare the files of the current task.
1852 * We don't want to expose copy_files internals to
1853 * the exec layer of the kernel.
1856 int unshare_files(struct files_struct
**displaced
)
1858 struct task_struct
*task
= current
;
1859 struct files_struct
*copy
= NULL
;
1862 error
= unshare_fd(CLONE_FILES
, ©
);
1863 if (error
|| !copy
) {
1867 *displaced
= task
->files
;