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/cpu.h>
32 #include <linux/cpuset.h>
33 #include <linux/security.h>
34 #include <linux/swap.h>
35 #include <linux/syscalls.h>
36 #include <linux/jiffies.h>
37 #include <linux/futex.h>
38 #include <linux/ptrace.h>
39 #include <linux/mount.h>
40 #include <linux/audit.h>
41 #include <linux/profile.h>
42 #include <linux/rmap.h>
43 #include <linux/acct.h>
45 #include <asm/pgtable.h>
46 #include <asm/pgalloc.h>
47 #include <asm/uaccess.h>
48 #include <asm/mmu_context.h>
49 #include <asm/cacheflush.h>
50 #include <asm/tlbflush.h>
53 * Protected counters by write_lock_irq(&tasklist_lock)
55 unsigned long total_forks; /* Handle normal Linux uptimes. */
56 int nr_threads; /* The idle threads do not count.. */
58 int max_threads; /* tunable limit on nr_threads */
60 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
62 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
64 EXPORT_SYMBOL(tasklist_lock);
66 int nr_processes(void)
71 for_each_online_cpu(cpu)
72 total += per_cpu(process_counts, cpu);
77 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
78 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
79 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
80 static kmem_cache_t *task_struct_cachep;
83 /* SLAB cache for signal_struct structures (tsk->signal) */
84 kmem_cache_t *signal_cachep;
86 /* SLAB cache for sighand_struct structures (tsk->sighand) */
87 kmem_cache_t *sighand_cachep;
89 /* SLAB cache for files_struct structures (tsk->files) */
90 kmem_cache_t *files_cachep;
92 /* SLAB cache for fs_struct structures (tsk->fs) */
93 kmem_cache_t *fs_cachep;
95 /* SLAB cache for vm_area_struct structures */
96 kmem_cache_t *vm_area_cachep;
98 /* SLAB cache for mm_struct structures (tsk->mm) */
99 static kmem_cache_t *mm_cachep;
101 void free_task(struct task_struct *tsk)
103 free_thread_info(tsk->thread_info);
104 free_task_struct(tsk);
106 EXPORT_SYMBOL(free_task);
108 void __put_task_struct(struct task_struct *tsk)
110 WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
111 WARN_ON(atomic_read(&tsk->usage));
112 WARN_ON(tsk == current);
114 if (unlikely(tsk->audit_context))
116 security_task_free(tsk);
118 put_group_info(tsk->group_info);
120 if (!profile_handoff_task(tsk))
124 void __init fork_init(unsigned long mempages)
126 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
127 #ifndef ARCH_MIN_TASKALIGN
128 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
130 /* create a slab on which task_structs can be allocated */
132 kmem_cache_create("task_struct", sizeof(struct task_struct),
133 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
137 * The default maximum number of threads is set to a safe
138 * value: the thread structures can take up at most half
141 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
144 * we need to allow at least 20 threads to boot a system
149 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
150 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
151 init_task.signal->rlim[RLIMIT_SIGPENDING] =
152 init_task.signal->rlim[RLIMIT_NPROC];
155 static struct task_struct *dup_task_struct(struct task_struct *orig)
157 struct task_struct *tsk;
158 struct thread_info *ti;
160 prepare_to_copy(orig);
162 tsk = alloc_task_struct();
166 ti = alloc_thread_info(tsk);
168 free_task_struct(tsk);
172 *ti = *orig->thread_info;
174 tsk->thread_info = ti;
177 /* One for us, one for whoever does the "release_task()" (usually parent) */
178 atomic_set(&tsk->usage,2);
179 atomic_set(&tsk->fs_excl, 0);
184 static inline int dup_mmap(struct mm_struct * mm, struct mm_struct * oldmm)
186 struct vm_area_struct * mpnt, *tmp, **pprev;
187 struct rb_node **rb_link, *rb_parent;
189 unsigned long charge;
190 struct mempolicy *pol;
192 down_write(&oldmm->mmap_sem);
193 flush_cache_mm(current->mm);
196 mm->mmap_cache = NULL;
197 mm->free_area_cache = oldmm->mmap_base;
198 mm->cached_hole_size = ~0UL;
200 set_mm_counter(mm, rss, 0);
201 set_mm_counter(mm, anon_rss, 0);
202 cpus_clear(mm->cpu_vm_mask);
204 rb_link = &mm->mm_rb.rb_node;
208 for (mpnt = current->mm->mmap ; mpnt ; mpnt = mpnt->vm_next) {
211 if (mpnt->vm_flags & VM_DONTCOPY) {
212 long pages = vma_pages(mpnt);
213 mm->total_vm -= pages;
214 __vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
219 if (mpnt->vm_flags & VM_ACCOUNT) {
220 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
221 if (security_vm_enough_memory(len))
225 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
229 pol = mpol_copy(vma_policy(mpnt));
230 retval = PTR_ERR(pol);
232 goto fail_nomem_policy;
233 vma_set_policy(tmp, pol);
234 tmp->vm_flags &= ~VM_LOCKED;
240 struct inode *inode = file->f_dentry->d_inode;
242 if (tmp->vm_flags & VM_DENYWRITE)
243 atomic_dec(&inode->i_writecount);
245 /* insert tmp into the share list, just after mpnt */
246 spin_lock(&file->f_mapping->i_mmap_lock);
247 tmp->vm_truncate_count = mpnt->vm_truncate_count;
248 flush_dcache_mmap_lock(file->f_mapping);
249 vma_prio_tree_add(tmp, mpnt);
250 flush_dcache_mmap_unlock(file->f_mapping);
251 spin_unlock(&file->f_mapping->i_mmap_lock);
255 * Link in the new vma and copy the page table entries:
256 * link in first so that swapoff can see swap entries.
257 * Note that, exceptionally, here the vma is inserted
258 * without holding mm->mmap_sem.
260 spin_lock(&mm->page_table_lock);
262 pprev = &tmp->vm_next;
264 __vma_link_rb(mm, tmp, rb_link, rb_parent);
265 rb_link = &tmp->vm_rb.rb_right;
266 rb_parent = &tmp->vm_rb;
269 retval = copy_page_range(mm, current->mm, tmp);
270 spin_unlock(&mm->page_table_lock);
272 if (tmp->vm_ops && tmp->vm_ops->open)
273 tmp->vm_ops->open(tmp);
281 flush_tlb_mm(current->mm);
282 up_write(&oldmm->mmap_sem);
285 kmem_cache_free(vm_area_cachep, tmp);
288 vm_unacct_memory(charge);
292 static inline int mm_alloc_pgd(struct mm_struct * mm)
294 mm->pgd = pgd_alloc(mm);
295 if (unlikely(!mm->pgd))
300 static inline void mm_free_pgd(struct mm_struct * mm)
305 #define dup_mmap(mm, oldmm) (0)
306 #define mm_alloc_pgd(mm) (0)
307 #define mm_free_pgd(mm)
308 #endif /* CONFIG_MMU */
310 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
312 #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
313 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
315 #include <linux/init_task.h>
317 static struct mm_struct * mm_init(struct mm_struct * mm)
319 atomic_set(&mm->mm_users, 1);
320 atomic_set(&mm->mm_count, 1);
321 init_rwsem(&mm->mmap_sem);
322 INIT_LIST_HEAD(&mm->mmlist);
323 mm->core_waiters = 0;
325 spin_lock_init(&mm->page_table_lock);
326 rwlock_init(&mm->ioctx_list_lock);
327 mm->ioctx_list = NULL;
328 mm->default_kioctx = (struct kioctx)INIT_KIOCTX(mm->default_kioctx, *mm);
329 mm->free_area_cache = TASK_UNMAPPED_BASE;
330 mm->cached_hole_size = ~0UL;
332 if (likely(!mm_alloc_pgd(mm))) {
341 * Allocate and initialize an mm_struct.
343 struct mm_struct * mm_alloc(void)
345 struct mm_struct * mm;
349 memset(mm, 0, sizeof(*mm));
356 * Called when the last reference to the mm
357 * is dropped: either by a lazy thread or by
358 * mmput. Free the page directory and the mm.
360 void fastcall __mmdrop(struct mm_struct *mm)
362 BUG_ON(mm == &init_mm);
369 * Decrement the use count and release all resources for an mm.
371 void mmput(struct mm_struct *mm)
373 if (atomic_dec_and_test(&mm->mm_users)) {
376 if (!list_empty(&mm->mmlist)) {
377 spin_lock(&mmlist_lock);
378 list_del(&mm->mmlist);
379 spin_unlock(&mmlist_lock);
385 EXPORT_SYMBOL_GPL(mmput);
388 * get_task_mm - acquire a reference to the task's mm
390 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
391 * this kernel workthread has transiently adopted a user mm with use_mm,
392 * to do its AIO) is not set and if so returns a reference to it, after
393 * bumping up the use count. User must release the mm via mmput()
394 * after use. Typically used by /proc and ptrace.
396 struct mm_struct *get_task_mm(struct task_struct *task)
398 struct mm_struct *mm;
403 if (task->flags & PF_BORROWED_MM)
406 atomic_inc(&mm->mm_users);
411 EXPORT_SYMBOL_GPL(get_task_mm);
413 /* Please note the differences between mmput and mm_release.
414 * mmput is called whenever we stop holding onto a mm_struct,
415 * error success whatever.
417 * mm_release is called after a mm_struct has been removed
418 * from the current process.
420 * This difference is important for error handling, when we
421 * only half set up a mm_struct for a new process and need to restore
422 * the old one. Because we mmput the new mm_struct before
423 * restoring the old one. . .
424 * Eric Biederman 10 January 1998
426 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
428 struct completion *vfork_done = tsk->vfork_done;
430 /* Get rid of any cached register state */
431 deactivate_mm(tsk, mm);
433 /* notify parent sleeping on vfork() */
435 tsk->vfork_done = NULL;
436 complete(vfork_done);
438 if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
439 u32 __user * tidptr = tsk->clear_child_tid;
440 tsk->clear_child_tid = NULL;
443 * We don't check the error code - if userspace has
444 * not set up a proper pointer then tough luck.
447 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
451 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
453 struct mm_struct * mm, *oldmm;
456 tsk->min_flt = tsk->maj_flt = 0;
457 tsk->nvcsw = tsk->nivcsw = 0;
460 tsk->active_mm = NULL;
463 * Are we cloning a kernel thread?
465 * We need to steal a active VM for that..
471 if (clone_flags & CLONE_VM) {
472 atomic_inc(&oldmm->mm_users);
475 * There are cases where the PTL is held to ensure no
476 * new threads start up in user mode using an mm, which
477 * allows optimizing out ipis; the tlb_gather_mmu code
480 spin_unlock_wait(&oldmm->page_table_lock);
489 /* Copy the current MM stuff.. */
490 memcpy(mm, oldmm, sizeof(*mm));
494 if (init_new_context(tsk,mm))
497 retval = dup_mmap(mm, oldmm);
501 mm->hiwater_rss = get_mm_counter(mm,rss);
502 mm->hiwater_vm = mm->total_vm;
516 * If init_new_context() failed, we cannot use mmput() to free the mm
517 * because it calls destroy_context()
524 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
526 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
527 /* We don't need to lock fs - think why ;-) */
529 atomic_set(&fs->count, 1);
530 rwlock_init(&fs->lock);
531 fs->umask = old->umask;
532 read_lock(&old->lock);
533 fs->rootmnt = mntget(old->rootmnt);
534 fs->root = dget(old->root);
535 fs->pwdmnt = mntget(old->pwdmnt);
536 fs->pwd = dget(old->pwd);
538 fs->altrootmnt = mntget(old->altrootmnt);
539 fs->altroot = dget(old->altroot);
541 fs->altrootmnt = NULL;
544 read_unlock(&old->lock);
549 struct fs_struct *copy_fs_struct(struct fs_struct *old)
551 return __copy_fs_struct(old);
554 EXPORT_SYMBOL_GPL(copy_fs_struct);
556 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
558 if (clone_flags & CLONE_FS) {
559 atomic_inc(¤t->fs->count);
562 tsk->fs = __copy_fs_struct(current->fs);
568 static int count_open_files(struct files_struct *files, int size)
573 /* Find the last open fd */
574 fdt = files_fdtable(files);
575 for (i = size/(8*sizeof(long)); i > 0; ) {
576 if (fdt->open_fds->fds_bits[--i])
579 i = (i+1) * 8 * sizeof(long);
583 static struct files_struct *alloc_files(void)
585 struct files_struct *newf;
588 newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
592 atomic_set(&newf->count, 1);
594 spin_lock_init(&newf->file_lock);
595 fdt = files_fdtable(newf);
597 fdt->max_fds = NR_OPEN_DEFAULT;
598 fdt->max_fdset = __FD_SETSIZE;
599 fdt->close_on_exec = &newf->close_on_exec_init;
600 fdt->open_fds = &newf->open_fds_init;
601 fdt->fd = &newf->fd_array[0];
606 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
608 struct files_struct *oldf, *newf;
609 struct file **old_fds, **new_fds;
610 int open_files, size, i, error = 0, expand;
611 struct fdtable *old_fdt, *new_fdt;
614 * A background process may not have any files ...
616 oldf = current->files;
620 if (clone_flags & CLONE_FILES) {
621 atomic_inc(&oldf->count);
626 * Note: we may be using current for both targets (See exec.c)
627 * This works because we cache current->files (old) as oldf. Don't
632 newf = alloc_files();
636 spin_lock(&oldf->file_lock);
637 old_fdt = files_fdtable(oldf);
638 new_fdt = files_fdtable(newf);
639 size = old_fdt->max_fdset;
640 open_files = count_open_files(oldf, old_fdt->max_fdset);
644 * Check whether we need to allocate a larger fd array or fd set.
645 * Note: we're not a clone task, so the open count won't change.
647 if (open_files > new_fdt->max_fdset) {
648 new_fdt->max_fdset = 0;
651 if (open_files > new_fdt->max_fds) {
652 new_fdt->max_fds = 0;
656 /* if the old fdset gets grown now, we'll only copy up to "size" fds */
658 spin_unlock(&oldf->file_lock);
659 spin_lock(&newf->file_lock);
660 error = expand_files(newf, open_files-1);
661 spin_unlock(&newf->file_lock);
664 spin_lock(&oldf->file_lock);
667 old_fds = old_fdt->fd;
668 new_fds = new_fdt->fd;
670 memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
671 memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
673 for (i = open_files; i != 0; i--) {
674 struct file *f = *old_fds++;
679 * The fd may be claimed in the fd bitmap but not yet
680 * instantiated in the files array if a sibling thread
681 * is partway through open(). So make sure that this
682 * fd is available to the new process.
684 FD_CLR(open_files - i, new_fdt->open_fds);
688 spin_unlock(&oldf->file_lock);
690 /* compute the remainder to be cleared */
691 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
693 /* This is long word aligned thus could use a optimized version */
694 memset(new_fds, 0, size);
696 if (new_fdt->max_fdset > open_files) {
697 int left = (new_fdt->max_fdset-open_files)/8;
698 int start = open_files / (8 * sizeof(unsigned long));
700 memset(&new_fdt->open_fds->fds_bits[start], 0, left);
701 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
710 free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
711 free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
712 free_fd_array(new_fdt->fd, new_fdt->max_fds);
713 kmem_cache_free(files_cachep, newf);
718 * Helper to unshare the files of the current task.
719 * We don't want to expose copy_files internals to
720 * the exec layer of the kernel.
723 int unshare_files(void)
725 struct files_struct *files = current->files;
731 /* This can race but the race causes us to copy when we don't
732 need to and drop the copy */
733 if(atomic_read(&files->count) == 1)
735 atomic_inc(&files->count);
738 rc = copy_files(0, current);
740 current->files = files;
744 EXPORT_SYMBOL(unshare_files);
746 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
748 struct sighand_struct *sig;
750 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
751 atomic_inc(¤t->sighand->count);
754 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
758 spin_lock_init(&sig->siglock);
759 atomic_set(&sig->count, 1);
760 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
764 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
766 struct signal_struct *sig;
769 if (clone_flags & CLONE_THREAD) {
770 atomic_inc(¤t->signal->count);
771 atomic_inc(¤t->signal->live);
774 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
779 ret = copy_thread_group_keys(tsk);
781 kmem_cache_free(signal_cachep, sig);
785 atomic_set(&sig->count, 1);
786 atomic_set(&sig->live, 1);
787 init_waitqueue_head(&sig->wait_chldexit);
789 sig->group_exit_code = 0;
790 sig->group_exit_task = NULL;
791 sig->group_stop_count = 0;
792 sig->curr_target = NULL;
793 init_sigpending(&sig->shared_pending);
794 INIT_LIST_HEAD(&sig->posix_timers);
796 sig->it_real_value = sig->it_real_incr = 0;
797 sig->real_timer.function = it_real_fn;
798 sig->real_timer.data = (unsigned long) tsk;
799 init_timer(&sig->real_timer);
801 sig->it_virt_expires = cputime_zero;
802 sig->it_virt_incr = cputime_zero;
803 sig->it_prof_expires = cputime_zero;
804 sig->it_prof_incr = cputime_zero;
806 sig->tty = current->signal->tty;
807 sig->pgrp = process_group(current);
808 sig->session = current->signal->session;
809 sig->leader = 0; /* session leadership doesn't inherit */
810 sig->tty_old_pgrp = 0;
812 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
813 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
814 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
816 INIT_LIST_HEAD(&sig->cpu_timers[0]);
817 INIT_LIST_HEAD(&sig->cpu_timers[1]);
818 INIT_LIST_HEAD(&sig->cpu_timers[2]);
820 task_lock(current->group_leader);
821 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
822 task_unlock(current->group_leader);
824 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
826 * New sole thread in the process gets an expiry time
827 * of the whole CPU time limit.
829 tsk->it_prof_expires =
830 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
836 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
838 unsigned long new_flags = p->flags;
840 new_flags &= ~PF_SUPERPRIV;
841 new_flags |= PF_FORKNOEXEC;
842 if (!(clone_flags & CLONE_PTRACE))
844 p->flags = new_flags;
847 asmlinkage long sys_set_tid_address(int __user *tidptr)
849 current->clear_child_tid = tidptr;
855 * This creates a new process as a copy of the old one,
856 * but does not actually start it yet.
858 * It copies the registers, and all the appropriate
859 * parts of the process environment (as per the clone
860 * flags). The actual kick-off is left to the caller.
862 static task_t *copy_process(unsigned long clone_flags,
863 unsigned long stack_start,
864 struct pt_regs *regs,
865 unsigned long stack_size,
866 int __user *parent_tidptr,
867 int __user *child_tidptr,
871 struct task_struct *p = NULL;
873 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
874 return ERR_PTR(-EINVAL);
877 * Thread groups must share signals as well, and detached threads
878 * can only be started up within the thread group.
880 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
881 return ERR_PTR(-EINVAL);
884 * Shared signal handlers imply shared VM. By way of the above,
885 * thread groups also imply shared VM. Blocking this case allows
886 * for various simplifications in other code.
888 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
889 return ERR_PTR(-EINVAL);
891 retval = security_task_create(clone_flags);
896 p = dup_task_struct(current);
901 if (atomic_read(&p->user->processes) >=
902 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
903 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
904 p->user != &root_user)
908 atomic_inc(&p->user->__count);
909 atomic_inc(&p->user->processes);
910 get_group_info(p->group_info);
913 * If multiple threads are within copy_process(), then this check
914 * triggers too late. This doesn't hurt, the check is only there
915 * to stop root fork bombs.
917 if (nr_threads >= max_threads)
918 goto bad_fork_cleanup_count;
920 if (!try_module_get(p->thread_info->exec_domain->module))
921 goto bad_fork_cleanup_count;
923 if (p->binfmt && !try_module_get(p->binfmt->module))
924 goto bad_fork_cleanup_put_domain;
927 copy_flags(clone_flags, p);
930 if (clone_flags & CLONE_PARENT_SETTID)
931 if (put_user(p->pid, parent_tidptr))
932 goto bad_fork_cleanup;
934 p->proc_dentry = NULL;
936 INIT_LIST_HEAD(&p->children);
937 INIT_LIST_HEAD(&p->sibling);
938 p->vfork_done = NULL;
939 spin_lock_init(&p->alloc_lock);
940 spin_lock_init(&p->proc_lock);
942 clear_tsk_thread_flag(p, TIF_SIGPENDING);
943 init_sigpending(&p->pending);
945 p->utime = cputime_zero;
946 p->stime = cputime_zero;
948 p->rchar = 0; /* I/O counter: bytes read */
949 p->wchar = 0; /* I/O counter: bytes written */
950 p->syscr = 0; /* I/O counter: read syscalls */
951 p->syscw = 0; /* I/O counter: write syscalls */
952 acct_clear_integrals(p);
954 p->it_virt_expires = cputime_zero;
955 p->it_prof_expires = cputime_zero;
956 p->it_sched_expires = 0;
957 INIT_LIST_HEAD(&p->cpu_timers[0]);
958 INIT_LIST_HEAD(&p->cpu_timers[1]);
959 INIT_LIST_HEAD(&p->cpu_timers[2]);
961 p->lock_depth = -1; /* -1 = no lock */
962 do_posix_clock_monotonic_gettime(&p->start_time);
964 p->io_context = NULL;
966 p->audit_context = NULL;
968 p->mempolicy = mpol_copy(p->mempolicy);
969 if (IS_ERR(p->mempolicy)) {
970 retval = PTR_ERR(p->mempolicy);
972 goto bad_fork_cleanup;
977 if (clone_flags & CLONE_THREAD)
978 p->tgid = current->tgid;
980 if ((retval = security_task_alloc(p)))
981 goto bad_fork_cleanup_policy;
982 if ((retval = audit_alloc(p)))
983 goto bad_fork_cleanup_security;
984 /* copy all the process information */
985 if ((retval = copy_semundo(clone_flags, p)))
986 goto bad_fork_cleanup_audit;
987 if ((retval = copy_files(clone_flags, p)))
988 goto bad_fork_cleanup_semundo;
989 if ((retval = copy_fs(clone_flags, p)))
990 goto bad_fork_cleanup_files;
991 if ((retval = copy_sighand(clone_flags, p)))
992 goto bad_fork_cleanup_fs;
993 if ((retval = copy_signal(clone_flags, p)))
994 goto bad_fork_cleanup_sighand;
995 if ((retval = copy_mm(clone_flags, p)))
996 goto bad_fork_cleanup_signal;
997 if ((retval = copy_keys(clone_flags, p)))
998 goto bad_fork_cleanup_mm;
999 if ((retval = copy_namespace(clone_flags, p)))
1000 goto bad_fork_cleanup_keys;
1001 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1003 goto bad_fork_cleanup_namespace;
1005 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1007 * Clear TID on mm_release()?
1009 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1012 * Syscall tracing should be turned off in the child regardless
1015 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1016 #ifdef TIF_SYSCALL_EMU
1017 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1020 /* Our parent execution domain becomes current domain
1021 These must match for thread signalling to apply */
1023 p->parent_exec_id = p->self_exec_id;
1025 /* ok, now we should be set up.. */
1026 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1027 p->pdeath_signal = 0;
1031 * Ok, make it visible to the rest of the system.
1032 * We dont wake it up yet.
1034 p->group_leader = p;
1035 INIT_LIST_HEAD(&p->ptrace_children);
1036 INIT_LIST_HEAD(&p->ptrace_list);
1038 /* Perform scheduler related setup. Assign this task to a CPU. */
1039 sched_fork(p, clone_flags);
1041 /* Need tasklist lock for parent etc handling! */
1042 write_lock_irq(&tasklist_lock);
1045 * The task hasn't been attached yet, so its cpus_allowed mask will
1046 * not be changed, nor will its assigned CPU.
1048 * The cpus_allowed mask of the parent may have changed after it was
1049 * copied first time - so re-copy it here, then check the child's CPU
1050 * to ensure it is on a valid CPU (and if not, just force it back to
1051 * parent's CPU). This avoids alot of nasty races.
1053 p->cpus_allowed = current->cpus_allowed;
1054 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed)))
1055 set_task_cpu(p, smp_processor_id());
1058 * Check for pending SIGKILL! The new thread should not be allowed
1059 * to slip out of an OOM kill. (or normal SIGKILL.)
1061 if (sigismember(¤t->pending.signal, SIGKILL)) {
1062 write_unlock_irq(&tasklist_lock);
1064 goto bad_fork_cleanup_namespace;
1067 /* CLONE_PARENT re-uses the old parent */
1068 if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1069 p->real_parent = current->real_parent;
1071 p->real_parent = current;
1072 p->parent = p->real_parent;
1074 if (clone_flags & CLONE_THREAD) {
1075 spin_lock(¤t->sighand->siglock);
1077 * Important: if an exit-all has been started then
1078 * do not create this new thread - the whole thread
1079 * group is supposed to exit anyway.
1081 if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1082 spin_unlock(¤t->sighand->siglock);
1083 write_unlock_irq(&tasklist_lock);
1085 goto bad_fork_cleanup_namespace;
1087 p->group_leader = current->group_leader;
1089 if (current->signal->group_stop_count > 0) {
1091 * There is an all-stop in progress for the group.
1092 * We ourselves will stop as soon as we check signals.
1093 * Make the new thread part of that group stop too.
1095 current->signal->group_stop_count++;
1096 set_tsk_thread_flag(p, TIF_SIGPENDING);
1099 if (!cputime_eq(current->signal->it_virt_expires,
1101 !cputime_eq(current->signal->it_prof_expires,
1103 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1104 !list_empty(¤t->signal->cpu_timers[0]) ||
1105 !list_empty(¤t->signal->cpu_timers[1]) ||
1106 !list_empty(¤t->signal->cpu_timers[2])) {
1108 * Have child wake up on its first tick to check
1109 * for process CPU timers.
1111 p->it_prof_expires = jiffies_to_cputime(1);
1114 spin_unlock(¤t->sighand->siglock);
1120 p->ioprio = current->ioprio;
1123 if (unlikely(p->ptrace & PT_PTRACED))
1124 __ptrace_link(p, current->parent);
1128 attach_pid(p, PIDTYPE_PID, p->pid);
1129 attach_pid(p, PIDTYPE_TGID, p->tgid);
1130 if (thread_group_leader(p)) {
1131 attach_pid(p, PIDTYPE_PGID, process_group(p));
1132 attach_pid(p, PIDTYPE_SID, p->signal->session);
1134 __get_cpu_var(process_counts)++;
1137 if (!current->signal->tty && p->signal->tty)
1138 p->signal->tty = NULL;
1142 write_unlock_irq(&tasklist_lock);
1147 return ERR_PTR(retval);
1150 bad_fork_cleanup_namespace:
1152 bad_fork_cleanup_keys:
1154 bad_fork_cleanup_mm:
1157 bad_fork_cleanup_signal:
1159 bad_fork_cleanup_sighand:
1161 bad_fork_cleanup_fs:
1162 exit_fs(p); /* blocking */
1163 bad_fork_cleanup_files:
1164 exit_files(p); /* blocking */
1165 bad_fork_cleanup_semundo:
1167 bad_fork_cleanup_audit:
1169 bad_fork_cleanup_security:
1170 security_task_free(p);
1171 bad_fork_cleanup_policy:
1173 mpol_free(p->mempolicy);
1177 module_put(p->binfmt->module);
1178 bad_fork_cleanup_put_domain:
1179 module_put(p->thread_info->exec_domain->module);
1180 bad_fork_cleanup_count:
1181 put_group_info(p->group_info);
1182 atomic_dec(&p->user->processes);
1189 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1191 memset(regs, 0, sizeof(struct pt_regs));
1195 task_t * __devinit fork_idle(int cpu)
1198 struct pt_regs regs;
1200 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0);
1202 return ERR_PTR(-ENOMEM);
1203 init_idle(task, cpu);
1204 unhash_process(task);
1208 static inline int fork_traceflag (unsigned clone_flags)
1210 if (clone_flags & CLONE_UNTRACED)
1212 else if (clone_flags & CLONE_VFORK) {
1213 if (current->ptrace & PT_TRACE_VFORK)
1214 return PTRACE_EVENT_VFORK;
1215 } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1216 if (current->ptrace & PT_TRACE_CLONE)
1217 return PTRACE_EVENT_CLONE;
1218 } else if (current->ptrace & PT_TRACE_FORK)
1219 return PTRACE_EVENT_FORK;
1225 * Ok, this is the main fork-routine.
1227 * It copies the process, and if successful kick-starts
1228 * it and waits for it to finish using the VM if required.
1230 long do_fork(unsigned long clone_flags,
1231 unsigned long stack_start,
1232 struct pt_regs *regs,
1233 unsigned long stack_size,
1234 int __user *parent_tidptr,
1235 int __user *child_tidptr)
1237 struct task_struct *p;
1239 long pid = alloc_pidmap();
1243 if (unlikely(current->ptrace)) {
1244 trace = fork_traceflag (clone_flags);
1246 clone_flags |= CLONE_PTRACE;
1249 p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
1251 * Do this prior waking up the new thread - the thread pointer
1252 * might get invalid after that point, if the thread exits quickly.
1255 struct completion vfork;
1257 if (clone_flags & CLONE_VFORK) {
1258 p->vfork_done = &vfork;
1259 init_completion(&vfork);
1262 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1264 * We'll start up with an immediate SIGSTOP.
1266 sigaddset(&p->pending.signal, SIGSTOP);
1267 set_tsk_thread_flag(p, TIF_SIGPENDING);
1270 if (!(clone_flags & CLONE_STOPPED))
1271 wake_up_new_task(p, clone_flags);
1273 p->state = TASK_STOPPED;
1275 if (unlikely (trace)) {
1276 current->ptrace_message = pid;
1277 ptrace_notify ((trace << 8) | SIGTRAP);
1280 if (clone_flags & CLONE_VFORK) {
1281 wait_for_completion(&vfork);
1282 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1283 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1292 void __init proc_caches_init(void)
1294 sighand_cachep = kmem_cache_create("sighand_cache",
1295 sizeof(struct sighand_struct), 0,
1296 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1297 signal_cachep = kmem_cache_create("signal_cache",
1298 sizeof(struct signal_struct), 0,
1299 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1300 files_cachep = kmem_cache_create("files_cache",
1301 sizeof(struct files_struct), 0,
1302 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1303 fs_cachep = kmem_cache_create("fs_cache",
1304 sizeof(struct fs_struct), 0,
1305 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1306 vm_area_cachep = kmem_cache_create("vm_area_struct",
1307 sizeof(struct vm_area_struct), 0,
1308 SLAB_PANIC, NULL, NULL);
1309 mm_cachep = kmem_cache_create("mm_struct",
1310 sizeof(struct mm_struct), 0,
1311 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);