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/config.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/unistd.h>
18 #include <linux/smp_lock.h>
19 #include <linux/module.h>
20 #include <linux/vmalloc.h>
21 #include <linux/completion.h>
22 #include <linux/namespace.h>
23 #include <linux/personality.h>
24 #include <linux/mempolicy.h>
25 #include <linux/sem.h>
26 #include <linux/file.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.h>
31 #include <linux/capability.h>
32 #include <linux/cpu.h>
33 #include <linux/cpuset.h>
34 #include <linux/security.h>
35 #include <linux/swap.h>
36 #include <linux/syscalls.h>
37 #include <linux/jiffies.h>
38 #include <linux/futex.h>
39 #include <linux/rcupdate.h>
40 #include <linux/ptrace.h>
41 #include <linux/mount.h>
42 #include <linux/audit.h>
43 #include <linux/profile.h>
44 #include <linux/rmap.h>
45 #include <linux/acct.h>
46 #include <linux/cn_proc.h>
48 #include <asm/pgtable.h>
49 #include <asm/pgalloc.h>
50 #include <asm/uaccess.h>
51 #include <asm/mmu_context.h>
52 #include <asm/cacheflush.h>
53 #include <asm/tlbflush.h>
56 * Protected counters by write_lock_irq(&tasklist_lock)
58 unsigned long total_forks
; /* Handle normal Linux uptimes. */
59 int nr_threads
; /* The idle threads do not count.. */
61 int max_threads
; /* tunable limit on nr_threads */
63 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
65 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
67 EXPORT_SYMBOL(tasklist_lock
);
69 int nr_processes(void)
74 for_each_online_cpu(cpu
)
75 total
+= per_cpu(process_counts
, cpu
);
80 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
81 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
82 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
83 static kmem_cache_t
*task_struct_cachep
;
86 /* SLAB cache for signal_struct structures (tsk->signal) */
87 kmem_cache_t
*signal_cachep
;
89 /* SLAB cache for sighand_struct structures (tsk->sighand) */
90 kmem_cache_t
*sighand_cachep
;
92 /* SLAB cache for files_struct structures (tsk->files) */
93 kmem_cache_t
*files_cachep
;
95 /* SLAB cache for fs_struct structures (tsk->fs) */
96 kmem_cache_t
*fs_cachep
;
98 /* SLAB cache for vm_area_struct structures */
99 kmem_cache_t
*vm_area_cachep
;
101 /* SLAB cache for mm_struct structures (tsk->mm) */
102 static kmem_cache_t
*mm_cachep
;
104 void free_task(struct task_struct
*tsk
)
106 free_thread_info(tsk
->thread_info
);
107 free_task_struct(tsk
);
109 EXPORT_SYMBOL(free_task
);
111 void __put_task_struct(struct task_struct
*tsk
)
113 WARN_ON(!(tsk
->exit_state
& (EXIT_DEAD
| EXIT_ZOMBIE
)));
114 WARN_ON(atomic_read(&tsk
->usage
));
115 WARN_ON(tsk
== current
);
117 if (unlikely(tsk
->audit_context
))
119 security_task_free(tsk
);
121 put_group_info(tsk
->group_info
);
123 if (!profile_handoff_task(tsk
))
127 void __init
fork_init(unsigned long mempages
)
129 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
130 #ifndef ARCH_MIN_TASKALIGN
131 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
133 /* create a slab on which task_structs can be allocated */
135 kmem_cache_create("task_struct", sizeof(struct task_struct
),
136 ARCH_MIN_TASKALIGN
, SLAB_PANIC
, NULL
, NULL
);
140 * The default maximum number of threads is set to a safe
141 * value: the thread structures can take up at most half
144 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
147 * we need to allow at least 20 threads to boot a system
152 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
153 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
154 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
155 init_task
.signal
->rlim
[RLIMIT_NPROC
];
158 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
160 struct task_struct
*tsk
;
161 struct thread_info
*ti
;
163 prepare_to_copy(orig
);
165 tsk
= alloc_task_struct();
169 ti
= alloc_thread_info(tsk
);
171 free_task_struct(tsk
);
176 tsk
->thread_info
= ti
;
177 setup_thread_stack(tsk
, orig
);
179 /* One for us, one for whoever does the "release_task()" (usually parent) */
180 atomic_set(&tsk
->usage
,2);
181 atomic_set(&tsk
->fs_excl
, 0);
186 static inline int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
188 struct vm_area_struct
*mpnt
, *tmp
, **pprev
;
189 struct rb_node
**rb_link
, *rb_parent
;
191 unsigned long charge
;
192 struct mempolicy
*pol
;
194 down_write(&oldmm
->mmap_sem
);
195 flush_cache_mm(oldmm
);
196 down_write(&mm
->mmap_sem
);
200 mm
->mmap_cache
= NULL
;
201 mm
->free_area_cache
= oldmm
->mmap_base
;
202 mm
->cached_hole_size
= ~0UL;
204 cpus_clear(mm
->cpu_vm_mask
);
206 rb_link
= &mm
->mm_rb
.rb_node
;
210 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
213 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
214 long pages
= vma_pages(mpnt
);
215 mm
->total_vm
-= pages
;
216 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
221 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
222 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
223 if (security_vm_enough_memory(len
))
227 tmp
= kmem_cache_alloc(vm_area_cachep
, SLAB_KERNEL
);
231 pol
= mpol_copy(vma_policy(mpnt
));
232 retval
= PTR_ERR(pol
);
234 goto fail_nomem_policy
;
235 vma_set_policy(tmp
, pol
);
236 tmp
->vm_flags
&= ~VM_LOCKED
;
242 struct inode
*inode
= file
->f_dentry
->d_inode
;
244 if (tmp
->vm_flags
& VM_DENYWRITE
)
245 atomic_dec(&inode
->i_writecount
);
247 /* insert tmp into the share list, just after mpnt */
248 spin_lock(&file
->f_mapping
->i_mmap_lock
);
249 tmp
->vm_truncate_count
= mpnt
->vm_truncate_count
;
250 flush_dcache_mmap_lock(file
->f_mapping
);
251 vma_prio_tree_add(tmp
, mpnt
);
252 flush_dcache_mmap_unlock(file
->f_mapping
);
253 spin_unlock(&file
->f_mapping
->i_mmap_lock
);
257 * Link in the new vma and copy the page table entries.
260 pprev
= &tmp
->vm_next
;
262 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
263 rb_link
= &tmp
->vm_rb
.rb_right
;
264 rb_parent
= &tmp
->vm_rb
;
267 retval
= copy_page_range(mm
, oldmm
, mpnt
);
269 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
270 tmp
->vm_ops
->open(tmp
);
277 up_write(&mm
->mmap_sem
);
279 up_write(&oldmm
->mmap_sem
);
282 kmem_cache_free(vm_area_cachep
, tmp
);
285 vm_unacct_memory(charge
);
289 static inline int mm_alloc_pgd(struct mm_struct
* mm
)
291 mm
->pgd
= pgd_alloc(mm
);
292 if (unlikely(!mm
->pgd
))
297 static inline void mm_free_pgd(struct mm_struct
* mm
)
302 #define dup_mmap(mm, oldmm) (0)
303 #define mm_alloc_pgd(mm) (0)
304 #define mm_free_pgd(mm)
305 #endif /* CONFIG_MMU */
307 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
309 #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
310 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
312 #include <linux/init_task.h>
314 static struct mm_struct
* mm_init(struct mm_struct
* mm
)
316 atomic_set(&mm
->mm_users
, 1);
317 atomic_set(&mm
->mm_count
, 1);
318 init_rwsem(&mm
->mmap_sem
);
319 INIT_LIST_HEAD(&mm
->mmlist
);
320 mm
->core_waiters
= 0;
322 set_mm_counter(mm
, file_rss
, 0);
323 set_mm_counter(mm
, anon_rss
, 0);
324 spin_lock_init(&mm
->page_table_lock
);
325 rwlock_init(&mm
->ioctx_list_lock
);
326 mm
->ioctx_list
= NULL
;
327 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
328 mm
->cached_hole_size
= ~0UL;
330 if (likely(!mm_alloc_pgd(mm
))) {
339 * Allocate and initialize an mm_struct.
341 struct mm_struct
* mm_alloc(void)
343 struct mm_struct
* mm
;
347 memset(mm
, 0, sizeof(*mm
));
354 * Called when the last reference to the mm
355 * is dropped: either by a lazy thread or by
356 * mmput. Free the page directory and the mm.
358 void fastcall
__mmdrop(struct mm_struct
*mm
)
360 BUG_ON(mm
== &init_mm
);
367 * Decrement the use count and release all resources for an mm.
369 void mmput(struct mm_struct
*mm
)
371 if (atomic_dec_and_test(&mm
->mm_users
)) {
374 if (!list_empty(&mm
->mmlist
)) {
375 spin_lock(&mmlist_lock
);
376 list_del(&mm
->mmlist
);
377 spin_unlock(&mmlist_lock
);
383 EXPORT_SYMBOL_GPL(mmput
);
386 * get_task_mm - acquire a reference to the task's mm
388 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
389 * this kernel workthread has transiently adopted a user mm with use_mm,
390 * to do its AIO) is not set and if so returns a reference to it, after
391 * bumping up the use count. User must release the mm via mmput()
392 * after use. Typically used by /proc and ptrace.
394 struct mm_struct
*get_task_mm(struct task_struct
*task
)
396 struct mm_struct
*mm
;
401 if (task
->flags
& PF_BORROWED_MM
)
404 atomic_inc(&mm
->mm_users
);
409 EXPORT_SYMBOL_GPL(get_task_mm
);
411 /* Please note the differences between mmput and mm_release.
412 * mmput is called whenever we stop holding onto a mm_struct,
413 * error success whatever.
415 * mm_release is called after a mm_struct has been removed
416 * from the current process.
418 * This difference is important for error handling, when we
419 * only half set up a mm_struct for a new process and need to restore
420 * the old one. Because we mmput the new mm_struct before
421 * restoring the old one. . .
422 * Eric Biederman 10 January 1998
424 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
426 struct completion
*vfork_done
= tsk
->vfork_done
;
428 /* Get rid of any cached register state */
429 deactivate_mm(tsk
, mm
);
431 /* notify parent sleeping on vfork() */
433 tsk
->vfork_done
= NULL
;
434 complete(vfork_done
);
436 if (tsk
->clear_child_tid
&& atomic_read(&mm
->mm_users
) > 1) {
437 u32 __user
* tidptr
= tsk
->clear_child_tid
;
438 tsk
->clear_child_tid
= NULL
;
441 * We don't check the error code - if userspace has
442 * not set up a proper pointer then tough luck.
445 sys_futex(tidptr
, FUTEX_WAKE
, 1, NULL
, NULL
, 0);
450 * Allocate a new mm structure and copy contents from the
451 * mm structure of the passed in task structure.
453 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
455 struct mm_struct
*mm
, *oldmm
= current
->mm
;
465 memcpy(mm
, oldmm
, sizeof(*mm
));
470 if (init_new_context(tsk
, mm
))
473 err
= dup_mmap(mm
, oldmm
);
477 mm
->hiwater_rss
= get_mm_rss(mm
);
478 mm
->hiwater_vm
= mm
->total_vm
;
490 * If init_new_context() failed, we cannot use mmput() to free the mm
491 * because it calls destroy_context()
498 static int copy_mm(unsigned long clone_flags
, struct task_struct
* tsk
)
500 struct mm_struct
* mm
, *oldmm
;
503 tsk
->min_flt
= tsk
->maj_flt
= 0;
504 tsk
->nvcsw
= tsk
->nivcsw
= 0;
507 tsk
->active_mm
= NULL
;
510 * Are we cloning a kernel thread?
512 * We need to steal a active VM for that..
518 if (clone_flags
& CLONE_VM
) {
519 atomic_inc(&oldmm
->mm_users
);
538 static inline struct fs_struct
*__copy_fs_struct(struct fs_struct
*old
)
540 struct fs_struct
*fs
= kmem_cache_alloc(fs_cachep
, GFP_KERNEL
);
541 /* We don't need to lock fs - think why ;-) */
543 atomic_set(&fs
->count
, 1);
544 rwlock_init(&fs
->lock
);
545 fs
->umask
= old
->umask
;
546 read_lock(&old
->lock
);
547 fs
->rootmnt
= mntget(old
->rootmnt
);
548 fs
->root
= dget(old
->root
);
549 fs
->pwdmnt
= mntget(old
->pwdmnt
);
550 fs
->pwd
= dget(old
->pwd
);
552 fs
->altrootmnt
= mntget(old
->altrootmnt
);
553 fs
->altroot
= dget(old
->altroot
);
555 fs
->altrootmnt
= NULL
;
558 read_unlock(&old
->lock
);
563 struct fs_struct
*copy_fs_struct(struct fs_struct
*old
)
565 return __copy_fs_struct(old
);
568 EXPORT_SYMBOL_GPL(copy_fs_struct
);
570 static inline int copy_fs(unsigned long clone_flags
, struct task_struct
* tsk
)
572 if (clone_flags
& CLONE_FS
) {
573 atomic_inc(¤t
->fs
->count
);
576 tsk
->fs
= __copy_fs_struct(current
->fs
);
582 static int count_open_files(struct fdtable
*fdt
)
584 int size
= fdt
->max_fdset
;
587 /* Find the last open fd */
588 for (i
= size
/(8*sizeof(long)); i
> 0; ) {
589 if (fdt
->open_fds
->fds_bits
[--i
])
592 i
= (i
+1) * 8 * sizeof(long);
596 static struct files_struct
*alloc_files(void)
598 struct files_struct
*newf
;
601 newf
= kmem_cache_alloc(files_cachep
, SLAB_KERNEL
);
605 atomic_set(&newf
->count
, 1);
607 spin_lock_init(&newf
->file_lock
);
610 fdt
->max_fds
= NR_OPEN_DEFAULT
;
611 fdt
->max_fdset
= __FD_SETSIZE
;
612 fdt
->close_on_exec
= &newf
->close_on_exec_init
;
613 fdt
->open_fds
= &newf
->open_fds_init
;
614 fdt
->fd
= &newf
->fd_array
[0];
615 INIT_RCU_HEAD(&fdt
->rcu
);
616 fdt
->free_files
= NULL
;
618 rcu_assign_pointer(newf
->fdt
, fdt
);
624 * Allocate a new files structure and copy contents from the
625 * passed in files structure.
627 static struct files_struct
*dup_fd(struct files_struct
*oldf
, int *errorp
)
629 struct files_struct
*newf
;
630 struct file
**old_fds
, **new_fds
;
631 int open_files
, size
, i
, expand
;
632 struct fdtable
*old_fdt
, *new_fdt
;
634 newf
= alloc_files();
638 spin_lock(&oldf
->file_lock
);
639 old_fdt
= files_fdtable(oldf
);
640 new_fdt
= files_fdtable(newf
);
641 size
= old_fdt
->max_fdset
;
642 open_files
= count_open_files(old_fdt
);
646 * Check whether we need to allocate a larger fd array or fd set.
647 * Note: we're not a clone task, so the open count won't change.
649 if (open_files
> new_fdt
->max_fdset
) {
650 new_fdt
->max_fdset
= 0;
653 if (open_files
> new_fdt
->max_fds
) {
654 new_fdt
->max_fds
= 0;
658 /* if the old fdset gets grown now, we'll only copy up to "size" fds */
660 spin_unlock(&oldf
->file_lock
);
661 spin_lock(&newf
->file_lock
);
662 *errorp
= expand_files(newf
, open_files
-1);
663 spin_unlock(&newf
->file_lock
);
666 new_fdt
= files_fdtable(newf
);
668 * Reacquire the oldf lock and a pointer to its fd table
669 * who knows it may have a new bigger fd table. We need
670 * the latest pointer.
672 spin_lock(&oldf
->file_lock
);
673 old_fdt
= files_fdtable(oldf
);
676 old_fds
= old_fdt
->fd
;
677 new_fds
= new_fdt
->fd
;
679 memcpy(new_fdt
->open_fds
->fds_bits
, old_fdt
->open_fds
->fds_bits
, open_files
/8);
680 memcpy(new_fdt
->close_on_exec
->fds_bits
, old_fdt
->close_on_exec
->fds_bits
, open_files
/8);
682 for (i
= open_files
; i
!= 0; i
--) {
683 struct file
*f
= *old_fds
++;
688 * The fd may be claimed in the fd bitmap but not yet
689 * instantiated in the files array if a sibling thread
690 * is partway through open(). So make sure that this
691 * fd is available to the new process.
693 FD_CLR(open_files
- i
, new_fdt
->open_fds
);
695 rcu_assign_pointer(*new_fds
++, f
);
697 spin_unlock(&oldf
->file_lock
);
699 /* compute the remainder to be cleared */
700 size
= (new_fdt
->max_fds
- open_files
) * sizeof(struct file
*);
702 /* This is long word aligned thus could use a optimized version */
703 memset(new_fds
, 0, size
);
705 if (new_fdt
->max_fdset
> open_files
) {
706 int left
= (new_fdt
->max_fdset
-open_files
)/8;
707 int start
= open_files
/ (8 * sizeof(unsigned long));
709 memset(&new_fdt
->open_fds
->fds_bits
[start
], 0, left
);
710 memset(&new_fdt
->close_on_exec
->fds_bits
[start
], 0, left
);
717 free_fdset (new_fdt
->close_on_exec
, new_fdt
->max_fdset
);
718 free_fdset (new_fdt
->open_fds
, new_fdt
->max_fdset
);
719 free_fd_array(new_fdt
->fd
, new_fdt
->max_fds
);
720 kmem_cache_free(files_cachep
, newf
);
724 static int copy_files(unsigned long clone_flags
, struct task_struct
* tsk
)
726 struct files_struct
*oldf
, *newf
;
730 * A background process may not have any files ...
732 oldf
= current
->files
;
736 if (clone_flags
& CLONE_FILES
) {
737 atomic_inc(&oldf
->count
);
742 * Note: we may be using current for both targets (See exec.c)
743 * This works because we cache current->files (old) as oldf. Don't
748 newf
= dup_fd(oldf
, &error
);
759 * Helper to unshare the files of the current task.
760 * We don't want to expose copy_files internals to
761 * the exec layer of the kernel.
764 int unshare_files(void)
766 struct files_struct
*files
= current
->files
;
772 /* This can race but the race causes us to copy when we don't
773 need to and drop the copy */
774 if(atomic_read(&files
->count
) == 1)
776 atomic_inc(&files
->count
);
779 rc
= copy_files(0, current
);
781 current
->files
= files
;
785 EXPORT_SYMBOL(unshare_files
);
787 void sighand_free_cb(struct rcu_head
*rhp
)
789 struct sighand_struct
*sp
;
791 sp
= container_of(rhp
, struct sighand_struct
, rcu
);
792 kmem_cache_free(sighand_cachep
, sp
);
795 static inline int copy_sighand(unsigned long clone_flags
, struct task_struct
* tsk
)
797 struct sighand_struct
*sig
;
799 if (clone_flags
& (CLONE_SIGHAND
| CLONE_THREAD
)) {
800 atomic_inc(¤t
->sighand
->count
);
803 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
804 rcu_assign_pointer(tsk
->sighand
, sig
);
807 spin_lock_init(&sig
->siglock
);
808 atomic_set(&sig
->count
, 1);
809 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
813 static inline int copy_signal(unsigned long clone_flags
, struct task_struct
* tsk
)
815 struct signal_struct
*sig
;
818 if (clone_flags
& CLONE_THREAD
) {
819 atomic_inc(¤t
->signal
->count
);
820 atomic_inc(¤t
->signal
->live
);
823 sig
= kmem_cache_alloc(signal_cachep
, GFP_KERNEL
);
828 ret
= copy_thread_group_keys(tsk
);
830 kmem_cache_free(signal_cachep
, sig
);
834 atomic_set(&sig
->count
, 1);
835 atomic_set(&sig
->live
, 1);
836 init_waitqueue_head(&sig
->wait_chldexit
);
838 sig
->group_exit_code
= 0;
839 sig
->group_exit_task
= NULL
;
840 sig
->group_stop_count
= 0;
841 sig
->curr_target
= NULL
;
842 init_sigpending(&sig
->shared_pending
);
843 INIT_LIST_HEAD(&sig
->posix_timers
);
845 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_REL
);
846 sig
->it_real_incr
.tv64
= 0;
847 sig
->real_timer
.function
= it_real_fn
;
848 sig
->real_timer
.data
= tsk
;
850 sig
->it_virt_expires
= cputime_zero
;
851 sig
->it_virt_incr
= cputime_zero
;
852 sig
->it_prof_expires
= cputime_zero
;
853 sig
->it_prof_incr
= cputime_zero
;
855 sig
->leader
= 0; /* session leadership doesn't inherit */
856 sig
->tty_old_pgrp
= 0;
858 sig
->utime
= sig
->stime
= sig
->cutime
= sig
->cstime
= cputime_zero
;
859 sig
->nvcsw
= sig
->nivcsw
= sig
->cnvcsw
= sig
->cnivcsw
= 0;
860 sig
->min_flt
= sig
->maj_flt
= sig
->cmin_flt
= sig
->cmaj_flt
= 0;
862 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
863 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
864 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
866 task_lock(current
->group_leader
);
867 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
868 task_unlock(current
->group_leader
);
870 if (sig
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
) {
872 * New sole thread in the process gets an expiry time
873 * of the whole CPU time limit.
875 tsk
->it_prof_expires
=
876 secs_to_cputime(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
882 static inline void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
884 unsigned long new_flags
= p
->flags
;
886 new_flags
&= ~(PF_SUPERPRIV
| PF_NOFREEZE
);
887 new_flags
|= PF_FORKNOEXEC
;
888 if (!(clone_flags
& CLONE_PTRACE
))
890 p
->flags
= new_flags
;
893 asmlinkage
long sys_set_tid_address(int __user
*tidptr
)
895 current
->clear_child_tid
= tidptr
;
901 * This creates a new process as a copy of the old one,
902 * but does not actually start it yet.
904 * It copies the registers, and all the appropriate
905 * parts of the process environment (as per the clone
906 * flags). The actual kick-off is left to the caller.
908 static task_t
*copy_process(unsigned long clone_flags
,
909 unsigned long stack_start
,
910 struct pt_regs
*regs
,
911 unsigned long stack_size
,
912 int __user
*parent_tidptr
,
913 int __user
*child_tidptr
,
917 struct task_struct
*p
= NULL
;
919 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
920 return ERR_PTR(-EINVAL
);
923 * Thread groups must share signals as well, and detached threads
924 * can only be started up within the thread group.
926 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
927 return ERR_PTR(-EINVAL
);
930 * Shared signal handlers imply shared VM. By way of the above,
931 * thread groups also imply shared VM. Blocking this case allows
932 * for various simplifications in other code.
934 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
935 return ERR_PTR(-EINVAL
);
937 retval
= security_task_create(clone_flags
);
942 p
= dup_task_struct(current
);
947 if (atomic_read(&p
->user
->processes
) >=
948 p
->signal
->rlim
[RLIMIT_NPROC
].rlim_cur
) {
949 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
950 p
->user
!= &root_user
)
954 atomic_inc(&p
->user
->__count
);
955 atomic_inc(&p
->user
->processes
);
956 get_group_info(p
->group_info
);
959 * If multiple threads are within copy_process(), then this check
960 * triggers too late. This doesn't hurt, the check is only there
961 * to stop root fork bombs.
963 if (nr_threads
>= max_threads
)
964 goto bad_fork_cleanup_count
;
966 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
967 goto bad_fork_cleanup_count
;
969 if (p
->binfmt
&& !try_module_get(p
->binfmt
->module
))
970 goto bad_fork_cleanup_put_domain
;
973 copy_flags(clone_flags
, p
);
976 if (clone_flags
& CLONE_PARENT_SETTID
)
977 if (put_user(p
->pid
, parent_tidptr
))
978 goto bad_fork_cleanup
;
980 p
->proc_dentry
= NULL
;
982 INIT_LIST_HEAD(&p
->children
);
983 INIT_LIST_HEAD(&p
->sibling
);
984 p
->vfork_done
= NULL
;
985 spin_lock_init(&p
->alloc_lock
);
986 spin_lock_init(&p
->proc_lock
);
988 clear_tsk_thread_flag(p
, TIF_SIGPENDING
);
989 init_sigpending(&p
->pending
);
991 p
->utime
= cputime_zero
;
992 p
->stime
= cputime_zero
;
994 p
->rchar
= 0; /* I/O counter: bytes read */
995 p
->wchar
= 0; /* I/O counter: bytes written */
996 p
->syscr
= 0; /* I/O counter: read syscalls */
997 p
->syscw
= 0; /* I/O counter: write syscalls */
998 acct_clear_integrals(p
);
1000 p
->it_virt_expires
= cputime_zero
;
1001 p
->it_prof_expires
= cputime_zero
;
1002 p
->it_sched_expires
= 0;
1003 INIT_LIST_HEAD(&p
->cpu_timers
[0]);
1004 INIT_LIST_HEAD(&p
->cpu_timers
[1]);
1005 INIT_LIST_HEAD(&p
->cpu_timers
[2]);
1007 p
->lock_depth
= -1; /* -1 = no lock */
1008 do_posix_clock_monotonic_gettime(&p
->start_time
);
1010 p
->io_context
= NULL
;
1012 p
->audit_context
= NULL
;
1015 p
->mempolicy
= mpol_copy(p
->mempolicy
);
1016 if (IS_ERR(p
->mempolicy
)) {
1017 retval
= PTR_ERR(p
->mempolicy
);
1018 p
->mempolicy
= NULL
;
1019 goto bad_fork_cleanup_cpuset
;
1023 #ifdef CONFIG_DEBUG_MUTEXES
1024 p
->blocked_on
= NULL
; /* not blocked yet */
1028 if (clone_flags
& CLONE_THREAD
)
1029 p
->tgid
= current
->tgid
;
1031 if ((retval
= security_task_alloc(p
)))
1032 goto bad_fork_cleanup_policy
;
1033 if ((retval
= audit_alloc(p
)))
1034 goto bad_fork_cleanup_security
;
1035 /* copy all the process information */
1036 if ((retval
= copy_semundo(clone_flags
, p
)))
1037 goto bad_fork_cleanup_audit
;
1038 if ((retval
= copy_files(clone_flags
, p
)))
1039 goto bad_fork_cleanup_semundo
;
1040 if ((retval
= copy_fs(clone_flags
, p
)))
1041 goto bad_fork_cleanup_files
;
1042 if ((retval
= copy_sighand(clone_flags
, p
)))
1043 goto bad_fork_cleanup_fs
;
1044 if ((retval
= copy_signal(clone_flags
, p
)))
1045 goto bad_fork_cleanup_sighand
;
1046 if ((retval
= copy_mm(clone_flags
, p
)))
1047 goto bad_fork_cleanup_signal
;
1048 if ((retval
= copy_keys(clone_flags
, p
)))
1049 goto bad_fork_cleanup_mm
;
1050 if ((retval
= copy_namespace(clone_flags
, p
)))
1051 goto bad_fork_cleanup_keys
;
1052 retval
= copy_thread(0, clone_flags
, stack_start
, stack_size
, p
, regs
);
1054 goto bad_fork_cleanup_namespace
;
1056 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1058 * Clear TID on mm_release()?
1060 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1063 * Syscall tracing should be turned off in the child regardless
1066 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1067 #ifdef TIF_SYSCALL_EMU
1068 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1071 /* Our parent execution domain becomes current domain
1072 These must match for thread signalling to apply */
1074 p
->parent_exec_id
= p
->self_exec_id
;
1076 /* ok, now we should be set up.. */
1077 p
->exit_signal
= (clone_flags
& CLONE_THREAD
) ? -1 : (clone_flags
& CSIGNAL
);
1078 p
->pdeath_signal
= 0;
1082 * Ok, make it visible to the rest of the system.
1083 * We dont wake it up yet.
1085 p
->group_leader
= p
;
1086 INIT_LIST_HEAD(&p
->ptrace_children
);
1087 INIT_LIST_HEAD(&p
->ptrace_list
);
1089 /* Perform scheduler related setup. Assign this task to a CPU. */
1090 sched_fork(p
, clone_flags
);
1092 /* Need tasklist lock for parent etc handling! */
1093 write_lock_irq(&tasklist_lock
);
1096 * The task hasn't been attached yet, so its cpus_allowed mask will
1097 * not be changed, nor will its assigned CPU.
1099 * The cpus_allowed mask of the parent may have changed after it was
1100 * copied first time - so re-copy it here, then check the child's CPU
1101 * to ensure it is on a valid CPU (and if not, just force it back to
1102 * parent's CPU). This avoids alot of nasty races.
1104 p
->cpus_allowed
= current
->cpus_allowed
;
1105 if (unlikely(!cpu_isset(task_cpu(p
), p
->cpus_allowed
) ||
1106 !cpu_online(task_cpu(p
))))
1107 set_task_cpu(p
, smp_processor_id());
1110 * Check for pending SIGKILL! The new thread should not be allowed
1111 * to slip out of an OOM kill. (or normal SIGKILL.)
1113 if (sigismember(¤t
->pending
.signal
, SIGKILL
)) {
1114 write_unlock_irq(&tasklist_lock
);
1116 goto bad_fork_cleanup_namespace
;
1119 /* CLONE_PARENT re-uses the old parent */
1120 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
))
1121 p
->real_parent
= current
->real_parent
;
1123 p
->real_parent
= current
;
1124 p
->parent
= p
->real_parent
;
1126 spin_lock(¤t
->sighand
->siglock
);
1127 if (clone_flags
& CLONE_THREAD
) {
1129 * Important: if an exit-all has been started then
1130 * do not create this new thread - the whole thread
1131 * group is supposed to exit anyway.
1133 if (current
->signal
->flags
& SIGNAL_GROUP_EXIT
) {
1134 spin_unlock(¤t
->sighand
->siglock
);
1135 write_unlock_irq(&tasklist_lock
);
1137 goto bad_fork_cleanup_namespace
;
1139 p
->group_leader
= current
->group_leader
;
1141 if (current
->signal
->group_stop_count
> 0) {
1143 * There is an all-stop in progress for the group.
1144 * We ourselves will stop as soon as we check signals.
1145 * Make the new thread part of that group stop too.
1147 current
->signal
->group_stop_count
++;
1148 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1151 if (!cputime_eq(current
->signal
->it_virt_expires
,
1153 !cputime_eq(current
->signal
->it_prof_expires
,
1155 current
->signal
->rlim
[RLIMIT_CPU
].rlim_cur
!= RLIM_INFINITY
||
1156 !list_empty(¤t
->signal
->cpu_timers
[0]) ||
1157 !list_empty(¤t
->signal
->cpu_timers
[1]) ||
1158 !list_empty(¤t
->signal
->cpu_timers
[2])) {
1160 * Have child wake up on its first tick to check
1161 * for process CPU timers.
1163 p
->it_prof_expires
= jiffies_to_cputime(1);
1170 p
->ioprio
= current
->ioprio
;
1173 if (unlikely(p
->ptrace
& PT_PTRACED
))
1174 __ptrace_link(p
, current
->parent
);
1176 if (thread_group_leader(p
)) {
1177 p
->signal
->tty
= current
->signal
->tty
;
1178 p
->signal
->pgrp
= process_group(current
);
1179 p
->signal
->session
= current
->signal
->session
;
1180 attach_pid(p
, PIDTYPE_PGID
, process_group(p
));
1181 attach_pid(p
, PIDTYPE_SID
, p
->signal
->session
);
1183 __get_cpu_var(process_counts
)++;
1185 attach_pid(p
, PIDTYPE_TGID
, p
->tgid
);
1186 attach_pid(p
, PIDTYPE_PID
, p
->pid
);
1190 spin_unlock(¤t
->sighand
->siglock
);
1191 write_unlock_irq(&tasklist_lock
);
1192 proc_fork_connector(p
);
1195 bad_fork_cleanup_namespace
:
1197 bad_fork_cleanup_keys
:
1199 bad_fork_cleanup_mm
:
1202 bad_fork_cleanup_signal
:
1204 bad_fork_cleanup_sighand
:
1206 bad_fork_cleanup_fs
:
1207 exit_fs(p
); /* blocking */
1208 bad_fork_cleanup_files
:
1209 exit_files(p
); /* blocking */
1210 bad_fork_cleanup_semundo
:
1212 bad_fork_cleanup_audit
:
1214 bad_fork_cleanup_security
:
1215 security_task_free(p
);
1216 bad_fork_cleanup_policy
:
1218 mpol_free(p
->mempolicy
);
1219 bad_fork_cleanup_cpuset
:
1224 module_put(p
->binfmt
->module
);
1225 bad_fork_cleanup_put_domain
:
1226 module_put(task_thread_info(p
)->exec_domain
->module
);
1227 bad_fork_cleanup_count
:
1228 put_group_info(p
->group_info
);
1229 atomic_dec(&p
->user
->processes
);
1234 return ERR_PTR(retval
);
1237 struct pt_regs
* __devinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1239 memset(regs
, 0, sizeof(struct pt_regs
));
1243 task_t
* __devinit
fork_idle(int cpu
)
1246 struct pt_regs regs
;
1248 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
, NULL
, 0);
1250 return ERR_PTR(-ENOMEM
);
1251 init_idle(task
, cpu
);
1252 unhash_process(task
);
1256 static inline int fork_traceflag (unsigned clone_flags
)
1258 if (clone_flags
& CLONE_UNTRACED
)
1260 else if (clone_flags
& CLONE_VFORK
) {
1261 if (current
->ptrace
& PT_TRACE_VFORK
)
1262 return PTRACE_EVENT_VFORK
;
1263 } else if ((clone_flags
& CSIGNAL
) != SIGCHLD
) {
1264 if (current
->ptrace
& PT_TRACE_CLONE
)
1265 return PTRACE_EVENT_CLONE
;
1266 } else if (current
->ptrace
& PT_TRACE_FORK
)
1267 return PTRACE_EVENT_FORK
;
1273 * Ok, this is the main fork-routine.
1275 * It copies the process, and if successful kick-starts
1276 * it and waits for it to finish using the VM if required.
1278 long do_fork(unsigned long clone_flags
,
1279 unsigned long stack_start
,
1280 struct pt_regs
*regs
,
1281 unsigned long stack_size
,
1282 int __user
*parent_tidptr
,
1283 int __user
*child_tidptr
)
1285 struct task_struct
*p
;
1287 long pid
= alloc_pidmap();
1291 if (unlikely(current
->ptrace
)) {
1292 trace
= fork_traceflag (clone_flags
);
1294 clone_flags
|= CLONE_PTRACE
;
1297 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
, parent_tidptr
, child_tidptr
, pid
);
1299 * Do this prior waking up the new thread - the thread pointer
1300 * might get invalid after that point, if the thread exits quickly.
1303 struct completion vfork
;
1305 if (clone_flags
& CLONE_VFORK
) {
1306 p
->vfork_done
= &vfork
;
1307 init_completion(&vfork
);
1310 if ((p
->ptrace
& PT_PTRACED
) || (clone_flags
& CLONE_STOPPED
)) {
1312 * We'll start up with an immediate SIGSTOP.
1314 sigaddset(&p
->pending
.signal
, SIGSTOP
);
1315 set_tsk_thread_flag(p
, TIF_SIGPENDING
);
1318 if (!(clone_flags
& CLONE_STOPPED
))
1319 wake_up_new_task(p
, clone_flags
);
1321 p
->state
= TASK_STOPPED
;
1323 if (unlikely (trace
)) {
1324 current
->ptrace_message
= pid
;
1325 ptrace_notify ((trace
<< 8) | SIGTRAP
);
1328 if (clone_flags
& CLONE_VFORK
) {
1329 wait_for_completion(&vfork
);
1330 if (unlikely (current
->ptrace
& PT_TRACE_VFORK_DONE
))
1331 ptrace_notify ((PTRACE_EVENT_VFORK_DONE
<< 8) | SIGTRAP
);
1340 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1341 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1344 void __init
proc_caches_init(void)
1346 sighand_cachep
= kmem_cache_create("sighand_cache",
1347 sizeof(struct sighand_struct
), 0,
1348 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1349 signal_cachep
= kmem_cache_create("signal_cache",
1350 sizeof(struct signal_struct
), 0,
1351 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1352 files_cachep
= kmem_cache_create("files_cache",
1353 sizeof(struct files_struct
), 0,
1354 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1355 fs_cachep
= kmem_cache_create("fs_cache",
1356 sizeof(struct fs_struct
), 0,
1357 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1358 vm_area_cachep
= kmem_cache_create("vm_area_struct",
1359 sizeof(struct vm_area_struct
), 0,
1360 SLAB_PANIC
, NULL
, NULL
);
1361 mm_cachep
= kmem_cache_create("mm_struct",
1362 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1363 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
, NULL
, NULL
);
1368 * Check constraints on flags passed to the unshare system call and
1369 * force unsharing of additional process context as appropriate.
1371 static inline void check_unshare_flags(unsigned long *flags_ptr
)
1374 * If unsharing a thread from a thread group, must also
1377 if (*flags_ptr
& CLONE_THREAD
)
1378 *flags_ptr
|= CLONE_VM
;
1381 * If unsharing vm, must also unshare signal handlers.
1383 if (*flags_ptr
& CLONE_VM
)
1384 *flags_ptr
|= CLONE_SIGHAND
;
1387 * If unsharing signal handlers and the task was created
1388 * using CLONE_THREAD, then must unshare the thread
1390 if ((*flags_ptr
& CLONE_SIGHAND
) &&
1391 (atomic_read(¤t
->signal
->count
) > 1))
1392 *flags_ptr
|= CLONE_THREAD
;
1395 * If unsharing namespace, must also unshare filesystem information.
1397 if (*flags_ptr
& CLONE_NEWNS
)
1398 *flags_ptr
|= CLONE_FS
;
1402 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1404 static int unshare_thread(unsigned long unshare_flags
)
1406 if (unshare_flags
& CLONE_THREAD
)
1413 * Unshare the filesystem structure if it is being shared
1415 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1417 struct fs_struct
*fs
= current
->fs
;
1419 if ((unshare_flags
& CLONE_FS
) &&
1420 (fs
&& atomic_read(&fs
->count
) > 1)) {
1421 *new_fsp
= __copy_fs_struct(current
->fs
);
1430 * Unshare the namespace structure if it is being shared
1432 static int unshare_namespace(unsigned long unshare_flags
, struct namespace **new_nsp
, struct fs_struct
*new_fs
)
1434 struct namespace *ns
= current
->namespace;
1436 if ((unshare_flags
& CLONE_NEWNS
) &&
1437 (ns
&& atomic_read(&ns
->count
) > 1)) {
1438 if (!capable(CAP_SYS_ADMIN
))
1441 *new_nsp
= dup_namespace(current
, new_fs
? new_fs
: current
->fs
);
1450 * Unsharing of sighand for tasks created with CLONE_SIGHAND is not
1453 static int unshare_sighand(unsigned long unshare_flags
, struct sighand_struct
**new_sighp
)
1455 struct sighand_struct
*sigh
= current
->sighand
;
1457 if ((unshare_flags
& CLONE_SIGHAND
) &&
1458 (sigh
&& atomic_read(&sigh
->count
) > 1))
1465 * Unshare vm if it is being shared
1467 static int unshare_vm(unsigned long unshare_flags
, struct mm_struct
**new_mmp
)
1469 struct mm_struct
*mm
= current
->mm
;
1471 if ((unshare_flags
& CLONE_VM
) &&
1472 (mm
&& atomic_read(&mm
->mm_users
) > 1)) {
1473 *new_mmp
= dup_mm(current
);
1482 * Unshare file descriptor table if it is being shared
1484 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1486 struct files_struct
*fd
= current
->files
;
1489 if ((unshare_flags
& CLONE_FILES
) &&
1490 (fd
&& atomic_read(&fd
->count
) > 1)) {
1491 *new_fdp
= dup_fd(fd
, &error
);
1500 * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not
1503 static int unshare_semundo(unsigned long unshare_flags
, struct sem_undo_list
**new_ulistp
)
1505 if (unshare_flags
& CLONE_SYSVSEM
)
1512 * unshare allows a process to 'unshare' part of the process
1513 * context which was originally shared using clone. copy_*
1514 * functions used by do_fork() cannot be used here directly
1515 * because they modify an inactive task_struct that is being
1516 * constructed. Here we are modifying the current, active,
1519 asmlinkage
long sys_unshare(unsigned long unshare_flags
)
1522 struct fs_struct
*fs
, *new_fs
= NULL
;
1523 struct namespace *ns
, *new_ns
= NULL
;
1524 struct sighand_struct
*sigh
, *new_sigh
= NULL
;
1525 struct mm_struct
*mm
, *new_mm
= NULL
, *active_mm
= NULL
;
1526 struct files_struct
*fd
, *new_fd
= NULL
;
1527 struct sem_undo_list
*new_ulist
= NULL
;
1529 check_unshare_flags(&unshare_flags
);
1531 if ((err
= unshare_thread(unshare_flags
)))
1532 goto bad_unshare_out
;
1533 if ((err
= unshare_fs(unshare_flags
, &new_fs
)))
1534 goto bad_unshare_cleanup_thread
;
1535 if ((err
= unshare_namespace(unshare_flags
, &new_ns
, new_fs
)))
1536 goto bad_unshare_cleanup_fs
;
1537 if ((err
= unshare_sighand(unshare_flags
, &new_sigh
)))
1538 goto bad_unshare_cleanup_ns
;
1539 if ((err
= unshare_vm(unshare_flags
, &new_mm
)))
1540 goto bad_unshare_cleanup_sigh
;
1541 if ((err
= unshare_fd(unshare_flags
, &new_fd
)))
1542 goto bad_unshare_cleanup_vm
;
1543 if ((err
= unshare_semundo(unshare_flags
, &new_ulist
)))
1544 goto bad_unshare_cleanup_fd
;
1546 if (new_fs
|| new_ns
|| new_sigh
|| new_mm
|| new_fd
|| new_ulist
) {
1552 current
->fs
= new_fs
;
1557 ns
= current
->namespace;
1558 current
->namespace = new_ns
;
1563 sigh
= current
->sighand
;
1564 current
->sighand
= new_sigh
;
1570 active_mm
= current
->active_mm
;
1571 current
->mm
= new_mm
;
1572 current
->active_mm
= new_mm
;
1573 activate_mm(active_mm
, new_mm
);
1578 fd
= current
->files
;
1579 current
->files
= new_fd
;
1583 task_unlock(current
);
1586 bad_unshare_cleanup_fd
:
1588 put_files_struct(new_fd
);
1590 bad_unshare_cleanup_vm
:
1594 bad_unshare_cleanup_sigh
:
1596 if (atomic_dec_and_test(&new_sigh
->count
))
1597 kmem_cache_free(sighand_cachep
, new_sigh
);
1599 bad_unshare_cleanup_ns
:
1601 put_namespace(new_ns
);
1603 bad_unshare_cleanup_fs
:
1605 put_fs_struct(new_fs
);
1607 bad_unshare_cleanup_thread
: