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/mnt_namespace.h>
21 #include <linux/personality.h>
22 #include <linux/mempolicy.h>
23 #include <linux/sem.h>
24 #include <linux/file.h>
25 #include <linux/fdtable.h>
26 #include <linux/iocontext.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.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/swap.h>
37 #include <linux/syscalls.h>
38 #include <linux/jiffies.h>
39 #include <linux/futex.h>
40 #include <linux/task_io_accounting_ops.h>
41 #include <linux/rcupdate.h>
42 #include <linux/ptrace.h>
43 #include <linux/mount.h>
44 #include <linux/audit.h>
45 #include <linux/memcontrol.h>
46 #include <linux/profile.h>
47 #include <linux/rmap.h>
48 #include <linux/acct.h>
49 #include <linux/tsacct_kern.h>
50 #include <linux/cn_proc.h>
51 #include <linux/freezer.h>
52 #include <linux/delayacct.h>
53 #include <linux/taskstats_kern.h>
54 #include <linux/random.h>
55 #include <linux/tty.h>
56 #include <linux/proc_fs.h>
57 #include <linux/blkdev.h>
59 #include <asm/pgtable.h>
60 #include <asm/pgalloc.h>
61 #include <asm/uaccess.h>
62 #include <asm/mmu_context.h>
63 #include <asm/cacheflush.h>
64 #include <asm/tlbflush.h>
67 * Protected counters by write_lock_irq(&tasklist_lock)
69 unsigned long total_forks; /* Handle normal Linux uptimes. */
70 int nr_threads; /* The idle threads do not count.. */
72 int max_threads; /* tunable limit on nr_threads */
74 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
76 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
78 int nr_processes(void)
83 for_each_online_cpu(cpu)
84 total += per_cpu(process_counts, cpu);
89 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
90 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
91 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
92 static struct kmem_cache *task_struct_cachep;
95 /* SLAB cache for signal_struct structures (tsk->signal) */
96 static struct kmem_cache *signal_cachep;
98 /* SLAB cache for sighand_struct structures (tsk->sighand) */
99 struct kmem_cache *sighand_cachep;
101 /* SLAB cache for files_struct structures (tsk->files) */
102 struct kmem_cache *files_cachep;
104 /* SLAB cache for fs_struct structures (tsk->fs) */
105 struct kmem_cache *fs_cachep;
107 /* SLAB cache for vm_area_struct structures */
108 struct kmem_cache *vm_area_cachep;
110 /* SLAB cache for mm_struct structures (tsk->mm) */
111 static struct kmem_cache *mm_cachep;
113 void free_task(struct task_struct *tsk)
115 prop_local_destroy_single(&tsk->dirties);
116 free_thread_info(tsk->stack);
117 rt_mutex_debug_task_free(tsk);
118 free_task_struct(tsk);
120 EXPORT_SYMBOL(free_task);
122 void __put_task_struct(struct task_struct *tsk)
124 WARN_ON(!tsk->exit_state);
125 WARN_ON(atomic_read(&tsk->usage));
126 WARN_ON(tsk == current);
128 security_task_free(tsk);
130 put_group_info(tsk->group_info);
131 delayacct_tsk_free(tsk);
133 if (!profile_handoff_task(tsk))
138 * macro override instead of weak attribute alias, to workaround
139 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
141 #ifndef arch_task_cache_init
142 #define arch_task_cache_init()
145 void __init fork_init(unsigned long mempages)
147 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
148 #ifndef ARCH_MIN_TASKALIGN
149 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
151 /* create a slab on which task_structs can be allocated */
153 kmem_cache_create("task_struct", sizeof(struct task_struct),
154 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL);
157 /* do the arch specific task caches init */
158 arch_task_cache_init();
161 * The default maximum number of threads is set to a safe
162 * value: the thread structures can take up at most half
165 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
168 * we need to allow at least 20 threads to boot a system
173 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
174 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
175 init_task.signal->rlim[RLIMIT_SIGPENDING] =
176 init_task.signal->rlim[RLIMIT_NPROC];
179 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
180 struct task_struct *src)
186 static struct task_struct *dup_task_struct(struct task_struct *orig)
188 struct task_struct *tsk;
189 struct thread_info *ti;
192 prepare_to_copy(orig);
194 tsk = alloc_task_struct();
198 ti = alloc_thread_info(tsk);
200 free_task_struct(tsk);
204 err = arch_dup_task_struct(tsk, orig);
210 err = prop_local_init_single(&tsk->dirties);
214 setup_thread_stack(tsk, orig);
216 #ifdef CONFIG_CC_STACKPROTECTOR
217 tsk->stack_canary = get_random_int();
220 /* One for us, one for whoever does the "release_task()" (usually parent) */
221 atomic_set(&tsk->usage,2);
222 atomic_set(&tsk->fs_excl, 0);
223 #ifdef CONFIG_BLK_DEV_IO_TRACE
226 tsk->splice_pipe = NULL;
230 free_thread_info(ti);
231 free_task_struct(tsk);
236 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
238 struct vm_area_struct *mpnt, *tmp, **pprev;
239 struct rb_node **rb_link, *rb_parent;
241 unsigned long charge;
242 struct mempolicy *pol;
244 down_write(&oldmm->mmap_sem);
245 flush_cache_dup_mm(oldmm);
247 * Not linked in yet - no deadlock potential:
249 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
253 mm->mmap_cache = NULL;
254 mm->free_area_cache = oldmm->mmap_base;
255 mm->cached_hole_size = ~0UL;
257 cpus_clear(mm->cpu_vm_mask);
259 rb_link = &mm->mm_rb.rb_node;
263 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
266 if (mpnt->vm_flags & VM_DONTCOPY) {
267 long pages = vma_pages(mpnt);
268 mm->total_vm -= pages;
269 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
274 if (mpnt->vm_flags & VM_ACCOUNT) {
275 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
276 if (security_vm_enough_memory(len))
280 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
284 pol = mpol_dup(vma_policy(mpnt));
285 retval = PTR_ERR(pol);
287 goto fail_nomem_policy;
288 vma_set_policy(tmp, pol);
289 tmp->vm_flags &= ~VM_LOCKED;
295 struct inode *inode = file->f_path.dentry->d_inode;
297 if (tmp->vm_flags & VM_DENYWRITE)
298 atomic_dec(&inode->i_writecount);
300 /* insert tmp into the share list, just after mpnt */
301 spin_lock(&file->f_mapping->i_mmap_lock);
302 tmp->vm_truncate_count = mpnt->vm_truncate_count;
303 flush_dcache_mmap_lock(file->f_mapping);
304 vma_prio_tree_add(tmp, mpnt);
305 flush_dcache_mmap_unlock(file->f_mapping);
306 spin_unlock(&file->f_mapping->i_mmap_lock);
310 * Link in the new vma and copy the page table entries.
313 pprev = &tmp->vm_next;
315 __vma_link_rb(mm, tmp, rb_link, rb_parent);
316 rb_link = &tmp->vm_rb.rb_right;
317 rb_parent = &tmp->vm_rb;
320 retval = copy_page_range(mm, oldmm, mpnt);
322 if (tmp->vm_ops && tmp->vm_ops->open)
323 tmp->vm_ops->open(tmp);
328 /* a new mm has just been created */
329 arch_dup_mmap(oldmm, mm);
332 up_write(&mm->mmap_sem);
334 up_write(&oldmm->mmap_sem);
337 kmem_cache_free(vm_area_cachep, tmp);
340 vm_unacct_memory(charge);
344 static inline int mm_alloc_pgd(struct mm_struct * mm)
346 mm->pgd = pgd_alloc(mm);
347 if (unlikely(!mm->pgd))
352 static inline void mm_free_pgd(struct mm_struct * mm)
354 pgd_free(mm, mm->pgd);
357 #define dup_mmap(mm, oldmm) (0)
358 #define mm_alloc_pgd(mm) (0)
359 #define mm_free_pgd(mm)
360 #endif /* CONFIG_MMU */
362 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
364 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
365 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
367 #include <linux/init_task.h>
369 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
371 atomic_set(&mm->mm_users, 1);
372 atomic_set(&mm->mm_count, 1);
373 init_rwsem(&mm->mmap_sem);
374 INIT_LIST_HEAD(&mm->mmlist);
375 mm->flags = (current->mm) ? current->mm->flags
376 : MMF_DUMP_FILTER_DEFAULT;
377 mm->core_waiters = 0;
379 set_mm_counter(mm, file_rss, 0);
380 set_mm_counter(mm, anon_rss, 0);
381 spin_lock_init(&mm->page_table_lock);
382 rwlock_init(&mm->ioctx_list_lock);
383 mm->ioctx_list = NULL;
384 mm->free_area_cache = TASK_UNMAPPED_BASE;
385 mm->cached_hole_size = ~0UL;
386 mm_init_owner(mm, p);
388 if (likely(!mm_alloc_pgd(mm))) {
398 * Allocate and initialize an mm_struct.
400 struct mm_struct * mm_alloc(void)
402 struct mm_struct * mm;
406 memset(mm, 0, sizeof(*mm));
407 mm = mm_init(mm, current);
413 * Called when the last reference to the mm
414 * is dropped: either by a lazy thread or by
415 * mmput. Free the page directory and the mm.
417 void __mmdrop(struct mm_struct *mm)
419 BUG_ON(mm == &init_mm);
424 EXPORT_SYMBOL_GPL(__mmdrop);
427 * Decrement the use count and release all resources for an mm.
429 void mmput(struct mm_struct *mm)
433 if (atomic_dec_and_test(&mm->mm_users)) {
436 set_mm_exe_file(mm, NULL);
437 if (!list_empty(&mm->mmlist)) {
438 spin_lock(&mmlist_lock);
439 list_del(&mm->mmlist);
440 spin_unlock(&mmlist_lock);
446 EXPORT_SYMBOL_GPL(mmput);
449 * get_task_mm - acquire a reference to the task's mm
451 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
452 * this kernel workthread has transiently adopted a user mm with use_mm,
453 * to do its AIO) is not set and if so returns a reference to it, after
454 * bumping up the use count. User must release the mm via mmput()
455 * after use. Typically used by /proc and ptrace.
457 struct mm_struct *get_task_mm(struct task_struct *task)
459 struct mm_struct *mm;
464 if (task->flags & PF_BORROWED_MM)
467 atomic_inc(&mm->mm_users);
472 EXPORT_SYMBOL_GPL(get_task_mm);
474 /* Please note the differences between mmput and mm_release.
475 * mmput is called whenever we stop holding onto a mm_struct,
476 * error success whatever.
478 * mm_release is called after a mm_struct has been removed
479 * from the current process.
481 * This difference is important for error handling, when we
482 * only half set up a mm_struct for a new process and need to restore
483 * the old one. Because we mmput the new mm_struct before
484 * restoring the old one. . .
485 * Eric Biederman 10 January 1998
487 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
489 struct completion *vfork_done = tsk->vfork_done;
491 /* Get rid of any cached register state */
492 deactivate_mm(tsk, mm);
494 /* notify parent sleeping on vfork() */
496 tsk->vfork_done = NULL;
497 complete(vfork_done);
501 * If we're exiting normally, clear a user-space tid field if
502 * requested. We leave this alone when dying by signal, to leave
503 * the value intact in a core dump, and to save the unnecessary
504 * trouble otherwise. Userland only wants this done for a sys_exit.
506 if (tsk->clear_child_tid
507 && !(tsk->flags & PF_SIGNALED)
508 && atomic_read(&mm->mm_users) > 1) {
509 u32 __user * tidptr = tsk->clear_child_tid;
510 tsk->clear_child_tid = NULL;
513 * We don't check the error code - if userspace has
514 * not set up a proper pointer then tough luck.
517 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
522 * Allocate a new mm structure and copy contents from the
523 * mm structure of the passed in task structure.
525 struct mm_struct *dup_mm(struct task_struct *tsk)
527 struct mm_struct *mm, *oldmm = current->mm;
537 memcpy(mm, oldmm, sizeof(*mm));
539 /* Initializing for Swap token stuff */
540 mm->token_priority = 0;
541 mm->last_interval = 0;
543 if (!mm_init(mm, tsk))
546 if (init_new_context(tsk, mm))
549 dup_mm_exe_file(oldmm, mm);
551 err = dup_mmap(mm, oldmm);
555 mm->hiwater_rss = get_mm_rss(mm);
556 mm->hiwater_vm = mm->total_vm;
568 * If init_new_context() failed, we cannot use mmput() to free the mm
569 * because it calls destroy_context()
576 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
578 struct mm_struct * mm, *oldmm;
581 tsk->min_flt = tsk->maj_flt = 0;
582 tsk->nvcsw = tsk->nivcsw = 0;
585 tsk->active_mm = NULL;
588 * Are we cloning a kernel thread?
590 * We need to steal a active VM for that..
596 if (clone_flags & CLONE_VM) {
597 atomic_inc(&oldmm->mm_users);
608 /* Initializing for Swap token stuff */
609 mm->token_priority = 0;
610 mm->last_interval = 0;
620 static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
622 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
623 /* We don't need to lock fs - think why ;-) */
625 atomic_set(&fs->count, 1);
626 rwlock_init(&fs->lock);
627 fs->umask = old->umask;
628 read_lock(&old->lock);
629 fs->root = old->root;
630 path_get(&old->root);
633 if (old->altroot.dentry) {
634 fs->altroot = old->altroot;
635 path_get(&old->altroot);
637 fs->altroot.mnt = NULL;
638 fs->altroot.dentry = NULL;
640 read_unlock(&old->lock);
645 struct fs_struct *copy_fs_struct(struct fs_struct *old)
647 return __copy_fs_struct(old);
650 EXPORT_SYMBOL_GPL(copy_fs_struct);
652 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
654 if (clone_flags & CLONE_FS) {
655 atomic_inc(¤t->fs->count);
658 tsk->fs = __copy_fs_struct(current->fs);
664 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
666 struct files_struct *oldf, *newf;
670 * A background process may not have any files ...
672 oldf = current->files;
676 if (clone_flags & CLONE_FILES) {
677 atomic_inc(&oldf->count);
681 newf = dup_fd(oldf, &error);
691 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
694 struct io_context *ioc = current->io_context;
699 * Share io context with parent, if CLONE_IO is set
701 if (clone_flags & CLONE_IO) {
702 tsk->io_context = ioc_task_link(ioc);
703 if (unlikely(!tsk->io_context))
705 } else if (ioprio_valid(ioc->ioprio)) {
706 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
707 if (unlikely(!tsk->io_context))
710 tsk->io_context->ioprio = ioc->ioprio;
716 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
718 struct sighand_struct *sig;
720 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
721 atomic_inc(¤t->sighand->count);
724 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
725 rcu_assign_pointer(tsk->sighand, sig);
728 atomic_set(&sig->count, 1);
729 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
733 void __cleanup_sighand(struct sighand_struct *sighand)
735 if (atomic_dec_and_test(&sighand->count))
736 kmem_cache_free(sighand_cachep, sighand);
739 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
741 struct signal_struct *sig;
744 if (clone_flags & CLONE_THREAD) {
745 atomic_inc(¤t->signal->count);
746 atomic_inc(¤t->signal->live);
749 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
754 ret = copy_thread_group_keys(tsk);
756 kmem_cache_free(signal_cachep, sig);
760 atomic_set(&sig->count, 1);
761 atomic_set(&sig->live, 1);
762 init_waitqueue_head(&sig->wait_chldexit);
764 sig->group_exit_code = 0;
765 sig->group_exit_task = NULL;
766 sig->group_stop_count = 0;
767 sig->curr_target = tsk;
768 init_sigpending(&sig->shared_pending);
769 INIT_LIST_HEAD(&sig->posix_timers);
771 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
772 sig->it_real_incr.tv64 = 0;
773 sig->real_timer.function = it_real_fn;
775 sig->it_virt_expires = cputime_zero;
776 sig->it_virt_incr = cputime_zero;
777 sig->it_prof_expires = cputime_zero;
778 sig->it_prof_incr = cputime_zero;
780 sig->leader = 0; /* session leadership doesn't inherit */
781 sig->tty_old_pgrp = NULL;
783 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
784 sig->gtime = cputime_zero;
785 sig->cgtime = cputime_zero;
786 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
787 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
788 sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
789 sig->sum_sched_runtime = 0;
790 INIT_LIST_HEAD(&sig->cpu_timers[0]);
791 INIT_LIST_HEAD(&sig->cpu_timers[1]);
792 INIT_LIST_HEAD(&sig->cpu_timers[2]);
793 taskstats_tgid_init(sig);
795 task_lock(current->group_leader);
796 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
797 task_unlock(current->group_leader);
799 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
801 * New sole thread in the process gets an expiry time
802 * of the whole CPU time limit.
804 tsk->it_prof_expires =
805 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
807 acct_init_pacct(&sig->pacct);
814 void __cleanup_signal(struct signal_struct *sig)
816 exit_thread_group_keys(sig);
817 kmem_cache_free(signal_cachep, sig);
820 static void cleanup_signal(struct task_struct *tsk)
822 struct signal_struct *sig = tsk->signal;
824 atomic_dec(&sig->live);
826 if (atomic_dec_and_test(&sig->count))
827 __cleanup_signal(sig);
830 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
832 unsigned long new_flags = p->flags;
834 new_flags &= ~PF_SUPERPRIV;
835 new_flags |= PF_FORKNOEXEC;
836 if (!(clone_flags & CLONE_PTRACE))
838 p->flags = new_flags;
839 clear_freeze_flag(p);
842 asmlinkage long sys_set_tid_address(int __user *tidptr)
844 current->clear_child_tid = tidptr;
846 return task_pid_vnr(current);
849 static void rt_mutex_init_task(struct task_struct *p)
851 spin_lock_init(&p->pi_lock);
852 #ifdef CONFIG_RT_MUTEXES
853 plist_head_init(&p->pi_waiters, &p->pi_lock);
854 p->pi_blocked_on = NULL;
858 #ifdef CONFIG_MM_OWNER
859 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
863 #endif /* CONFIG_MM_OWNER */
866 * This creates a new process as a copy of the old one,
867 * but does not actually start it yet.
869 * It copies the registers, and all the appropriate
870 * parts of the process environment (as per the clone
871 * flags). The actual kick-off is left to the caller.
873 static struct task_struct *copy_process(unsigned long clone_flags,
874 unsigned long stack_start,
875 struct pt_regs *regs,
876 unsigned long stack_size,
877 int __user *child_tidptr,
881 struct task_struct *p;
882 int cgroup_callbacks_done = 0;
884 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
885 return ERR_PTR(-EINVAL);
888 * Thread groups must share signals as well, and detached threads
889 * can only be started up within the thread group.
891 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
892 return ERR_PTR(-EINVAL);
895 * Shared signal handlers imply shared VM. By way of the above,
896 * thread groups also imply shared VM. Blocking this case allows
897 * for various simplifications in other code.
899 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
900 return ERR_PTR(-EINVAL);
902 retval = security_task_create(clone_flags);
907 p = dup_task_struct(current);
911 rt_mutex_init_task(p);
913 #ifdef CONFIG_PROVE_LOCKING
914 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
915 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
918 if (atomic_read(&p->user->processes) >=
919 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
920 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
921 p->user != current->nsproxy->user_ns->root_user)
925 atomic_inc(&p->user->__count);
926 atomic_inc(&p->user->processes);
927 get_group_info(p->group_info);
930 * If multiple threads are within copy_process(), then this check
931 * triggers too late. This doesn't hurt, the check is only there
932 * to stop root fork bombs.
934 if (nr_threads >= max_threads)
935 goto bad_fork_cleanup_count;
937 if (!try_module_get(task_thread_info(p)->exec_domain->module))
938 goto bad_fork_cleanup_count;
940 if (p->binfmt && !try_module_get(p->binfmt->module))
941 goto bad_fork_cleanup_put_domain;
944 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
945 copy_flags(clone_flags, p);
946 INIT_LIST_HEAD(&p->children);
947 INIT_LIST_HEAD(&p->sibling);
948 #ifdef CONFIG_PREEMPT_RCU
949 p->rcu_read_lock_nesting = 0;
950 p->rcu_flipctr_idx = 0;
951 #endif /* #ifdef CONFIG_PREEMPT_RCU */
952 p->vfork_done = NULL;
953 spin_lock_init(&p->alloc_lock);
955 clear_tsk_thread_flag(p, TIF_SIGPENDING);
956 init_sigpending(&p->pending);
958 p->utime = cputime_zero;
959 p->stime = cputime_zero;
960 p->gtime = cputime_zero;
961 p->utimescaled = cputime_zero;
962 p->stimescaled = cputime_zero;
963 p->prev_utime = cputime_zero;
964 p->prev_stime = cputime_zero;
966 #ifdef CONFIG_DETECT_SOFTLOCKUP
967 p->last_switch_count = 0;
968 p->last_switch_timestamp = 0;
971 #ifdef CONFIG_TASK_XACCT
972 p->rchar = 0; /* I/O counter: bytes read */
973 p->wchar = 0; /* I/O counter: bytes written */
974 p->syscr = 0; /* I/O counter: read syscalls */
975 p->syscw = 0; /* I/O counter: write syscalls */
977 task_io_accounting_init(p);
978 acct_clear_integrals(p);
980 p->it_virt_expires = cputime_zero;
981 p->it_prof_expires = cputime_zero;
982 p->it_sched_expires = 0;
983 INIT_LIST_HEAD(&p->cpu_timers[0]);
984 INIT_LIST_HEAD(&p->cpu_timers[1]);
985 INIT_LIST_HEAD(&p->cpu_timers[2]);
987 p->lock_depth = -1; /* -1 = no lock */
988 do_posix_clock_monotonic_gettime(&p->start_time);
989 p->real_start_time = p->start_time;
990 monotonic_to_bootbased(&p->real_start_time);
991 #ifdef CONFIG_SECURITY
994 p->cap_bset = current->cap_bset;
995 p->io_context = NULL;
996 p->audit_context = NULL;
999 p->mempolicy = mpol_dup(p->mempolicy);
1000 if (IS_ERR(p->mempolicy)) {
1001 retval = PTR_ERR(p->mempolicy);
1002 p->mempolicy = NULL;
1003 goto bad_fork_cleanup_cgroup;
1005 mpol_fix_fork_child_flag(p);
1007 #ifdef CONFIG_TRACE_IRQFLAGS
1009 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1010 p->hardirqs_enabled = 1;
1012 p->hardirqs_enabled = 0;
1014 p->hardirq_enable_ip = 0;
1015 p->hardirq_enable_event = 0;
1016 p->hardirq_disable_ip = _THIS_IP_;
1017 p->hardirq_disable_event = 0;
1018 p->softirqs_enabled = 1;
1019 p->softirq_enable_ip = _THIS_IP_;
1020 p->softirq_enable_event = 0;
1021 p->softirq_disable_ip = 0;
1022 p->softirq_disable_event = 0;
1023 p->hardirq_context = 0;
1024 p->softirq_context = 0;
1026 #ifdef CONFIG_LOCKDEP
1027 p->lockdep_depth = 0; /* no locks held yet */
1028 p->curr_chain_key = 0;
1029 p->lockdep_recursion = 0;
1032 #ifdef CONFIG_DEBUG_MUTEXES
1033 p->blocked_on = NULL; /* not blocked yet */
1036 /* Perform scheduler related setup. Assign this task to a CPU. */
1037 sched_fork(p, clone_flags);
1039 if ((retval = security_task_alloc(p)))
1040 goto bad_fork_cleanup_policy;
1041 if ((retval = audit_alloc(p)))
1042 goto bad_fork_cleanup_security;
1043 /* copy all the process information */
1044 if ((retval = copy_semundo(clone_flags, p)))
1045 goto bad_fork_cleanup_audit;
1046 if ((retval = copy_files(clone_flags, p)))
1047 goto bad_fork_cleanup_semundo;
1048 if ((retval = copy_fs(clone_flags, p)))
1049 goto bad_fork_cleanup_files;
1050 if ((retval = copy_sighand(clone_flags, p)))
1051 goto bad_fork_cleanup_fs;
1052 if ((retval = copy_signal(clone_flags, p)))
1053 goto bad_fork_cleanup_sighand;
1054 if ((retval = copy_mm(clone_flags, p)))
1055 goto bad_fork_cleanup_signal;
1056 if ((retval = copy_keys(clone_flags, p)))
1057 goto bad_fork_cleanup_mm;
1058 if ((retval = copy_namespaces(clone_flags, p)))
1059 goto bad_fork_cleanup_keys;
1060 if ((retval = copy_io(clone_flags, p)))
1061 goto bad_fork_cleanup_namespaces;
1062 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1064 goto bad_fork_cleanup_io;
1066 if (pid != &init_struct_pid) {
1068 pid = alloc_pid(task_active_pid_ns(p));
1070 goto bad_fork_cleanup_io;
1072 if (clone_flags & CLONE_NEWPID) {
1073 retval = pid_ns_prepare_proc(task_active_pid_ns(p));
1075 goto bad_fork_free_pid;
1079 p->pid = pid_nr(pid);
1081 if (clone_flags & CLONE_THREAD)
1082 p->tgid = current->tgid;
1084 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1086 * Clear TID on mm_release()?
1088 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1090 p->robust_list = NULL;
1091 #ifdef CONFIG_COMPAT
1092 p->compat_robust_list = NULL;
1094 INIT_LIST_HEAD(&p->pi_state_list);
1095 p->pi_state_cache = NULL;
1098 * sigaltstack should be cleared when sharing the same VM
1100 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1101 p->sas_ss_sp = p->sas_ss_size = 0;
1104 * Syscall tracing should be turned off in the child regardless
1107 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1108 #ifdef TIF_SYSCALL_EMU
1109 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1111 clear_all_latency_tracing(p);
1113 /* Our parent execution domain becomes current domain
1114 These must match for thread signalling to apply */
1115 p->parent_exec_id = p->self_exec_id;
1117 /* ok, now we should be set up.. */
1118 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1119 p->pdeath_signal = 0;
1123 * Ok, make it visible to the rest of the system.
1124 * We dont wake it up yet.
1126 p->group_leader = p;
1127 INIT_LIST_HEAD(&p->thread_group);
1128 INIT_LIST_HEAD(&p->ptrace_children);
1129 INIT_LIST_HEAD(&p->ptrace_list);
1131 /* Now that the task is set up, run cgroup callbacks if
1132 * necessary. We need to run them before the task is visible
1133 * on the tasklist. */
1134 cgroup_fork_callbacks(p);
1135 cgroup_callbacks_done = 1;
1137 /* Need tasklist lock for parent etc handling! */
1138 write_lock_irq(&tasklist_lock);
1141 * The task hasn't been attached yet, so its cpus_allowed mask will
1142 * not be changed, nor will its assigned CPU.
1144 * The cpus_allowed mask of the parent may have changed after it was
1145 * copied first time - so re-copy it here, then check the child's CPU
1146 * to ensure it is on a valid CPU (and if not, just force it back to
1147 * parent's CPU). This avoids alot of nasty races.
1149 p->cpus_allowed = current->cpus_allowed;
1150 p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
1151 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1152 !cpu_online(task_cpu(p))))
1153 set_task_cpu(p, smp_processor_id());
1155 /* CLONE_PARENT re-uses the old parent */
1156 if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1157 p->real_parent = current->real_parent;
1159 p->real_parent = current;
1160 p->parent = p->real_parent;
1162 spin_lock(¤t->sighand->siglock);
1165 * Process group and session signals need to be delivered to just the
1166 * parent before the fork or both the parent and the child after the
1167 * fork. Restart if a signal comes in before we add the new process to
1168 * it's process group.
1169 * A fatal signal pending means that current will exit, so the new
1170 * thread can't slip out of an OOM kill (or normal SIGKILL).
1172 recalc_sigpending();
1173 if (signal_pending(current)) {
1174 spin_unlock(¤t->sighand->siglock);
1175 write_unlock_irq(&tasklist_lock);
1176 retval = -ERESTARTNOINTR;
1177 goto bad_fork_free_pid;
1180 if (clone_flags & CLONE_THREAD) {
1181 p->group_leader = current->group_leader;
1182 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1184 if (!cputime_eq(current->signal->it_virt_expires,
1186 !cputime_eq(current->signal->it_prof_expires,
1188 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1189 !list_empty(¤t->signal->cpu_timers[0]) ||
1190 !list_empty(¤t->signal->cpu_timers[1]) ||
1191 !list_empty(¤t->signal->cpu_timers[2])) {
1193 * Have child wake up on its first tick to check
1194 * for process CPU timers.
1196 p->it_prof_expires = jiffies_to_cputime(1);
1200 if (likely(p->pid)) {
1202 if (unlikely(p->ptrace & PT_PTRACED))
1203 __ptrace_link(p, current->parent);
1205 if (thread_group_leader(p)) {
1206 if (clone_flags & CLONE_NEWPID)
1207 p->nsproxy->pid_ns->child_reaper = p;
1209 p->signal->leader_pid = pid;
1210 p->signal->tty = current->signal->tty;
1211 set_task_pgrp(p, task_pgrp_nr(current));
1212 set_task_session(p, task_session_nr(current));
1213 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1214 attach_pid(p, PIDTYPE_SID, task_session(current));
1215 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1216 __get_cpu_var(process_counts)++;
1218 attach_pid(p, PIDTYPE_PID, pid);
1223 spin_unlock(¤t->sighand->siglock);
1224 write_unlock_irq(&tasklist_lock);
1225 proc_fork_connector(p);
1226 cgroup_post_fork(p);
1230 if (pid != &init_struct_pid)
1232 bad_fork_cleanup_io:
1233 put_io_context(p->io_context);
1234 bad_fork_cleanup_namespaces:
1235 exit_task_namespaces(p);
1236 bad_fork_cleanup_keys:
1238 bad_fork_cleanup_mm:
1241 bad_fork_cleanup_signal:
1243 bad_fork_cleanup_sighand:
1244 __cleanup_sighand(p->sighand);
1245 bad_fork_cleanup_fs:
1246 exit_fs(p); /* blocking */
1247 bad_fork_cleanup_files:
1248 exit_files(p); /* blocking */
1249 bad_fork_cleanup_semundo:
1251 bad_fork_cleanup_audit:
1253 bad_fork_cleanup_security:
1254 security_task_free(p);
1255 bad_fork_cleanup_policy:
1257 mpol_put(p->mempolicy);
1258 bad_fork_cleanup_cgroup:
1260 cgroup_exit(p, cgroup_callbacks_done);
1261 delayacct_tsk_free(p);
1263 module_put(p->binfmt->module);
1264 bad_fork_cleanup_put_domain:
1265 module_put(task_thread_info(p)->exec_domain->module);
1266 bad_fork_cleanup_count:
1267 put_group_info(p->group_info);
1268 atomic_dec(&p->user->processes);
1273 return ERR_PTR(retval);
1276 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1278 memset(regs, 0, sizeof(struct pt_regs));
1282 struct task_struct * __cpuinit fork_idle(int cpu)
1284 struct task_struct *task;
1285 struct pt_regs regs;
1287 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1290 init_idle(task, cpu);
1295 static int fork_traceflag(unsigned clone_flags)
1297 if (clone_flags & CLONE_UNTRACED)
1299 else if (clone_flags & CLONE_VFORK) {
1300 if (current->ptrace & PT_TRACE_VFORK)
1301 return PTRACE_EVENT_VFORK;
1302 } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1303 if (current->ptrace & PT_TRACE_CLONE)
1304 return PTRACE_EVENT_CLONE;
1305 } else if (current->ptrace & PT_TRACE_FORK)
1306 return PTRACE_EVENT_FORK;
1312 * Ok, this is the main fork-routine.
1314 * It copies the process, and if successful kick-starts
1315 * it and waits for it to finish using the VM if required.
1317 long do_fork(unsigned long clone_flags,
1318 unsigned long stack_start,
1319 struct pt_regs *regs,
1320 unsigned long stack_size,
1321 int __user *parent_tidptr,
1322 int __user *child_tidptr)
1324 struct task_struct *p;
1329 * We hope to recycle these flags after 2.6.26
1331 if (unlikely(clone_flags & CLONE_STOPPED)) {
1332 static int __read_mostly count = 100;
1334 if (count > 0 && printk_ratelimit()) {
1335 char comm[TASK_COMM_LEN];
1338 printk(KERN_INFO "fork(): process `%s' used deprecated "
1339 "clone flags 0x%lx\n",
1340 get_task_comm(comm, current),
1341 clone_flags & CLONE_STOPPED);
1345 if (unlikely(current->ptrace)) {
1346 trace = fork_traceflag (clone_flags);
1348 clone_flags |= CLONE_PTRACE;
1351 p = copy_process(clone_flags, stack_start, regs, stack_size,
1352 child_tidptr, NULL);
1354 * Do this prior waking up the new thread - the thread pointer
1355 * might get invalid after that point, if the thread exits quickly.
1358 struct completion vfork;
1360 nr = task_pid_vnr(p);
1362 if (clone_flags & CLONE_PARENT_SETTID)
1363 put_user(nr, parent_tidptr);
1365 if (clone_flags & CLONE_VFORK) {
1366 p->vfork_done = &vfork;
1367 init_completion(&vfork);
1370 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1372 * We'll start up with an immediate SIGSTOP.
1374 sigaddset(&p->pending.signal, SIGSTOP);
1375 set_tsk_thread_flag(p, TIF_SIGPENDING);
1378 if (!(clone_flags & CLONE_STOPPED))
1379 wake_up_new_task(p, clone_flags);
1381 __set_task_state(p, TASK_STOPPED);
1383 if (unlikely (trace)) {
1384 current->ptrace_message = nr;
1385 ptrace_notify ((trace << 8) | SIGTRAP);
1388 if (clone_flags & CLONE_VFORK) {
1389 freezer_do_not_count();
1390 wait_for_completion(&vfork);
1392 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
1393 current->ptrace_message = nr;
1394 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1403 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1404 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1407 static void sighand_ctor(struct kmem_cache *cachep, void *data)
1409 struct sighand_struct *sighand = data;
1411 spin_lock_init(&sighand->siglock);
1412 init_waitqueue_head(&sighand->signalfd_wqh);
1415 void __init proc_caches_init(void)
1417 sighand_cachep = kmem_cache_create("sighand_cache",
1418 sizeof(struct sighand_struct), 0,
1419 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
1421 signal_cachep = kmem_cache_create("signal_cache",
1422 sizeof(struct signal_struct), 0,
1423 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1424 files_cachep = kmem_cache_create("files_cache",
1425 sizeof(struct files_struct), 0,
1426 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1427 fs_cachep = kmem_cache_create("fs_cache",
1428 sizeof(struct fs_struct), 0,
1429 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1430 vm_area_cachep = kmem_cache_create("vm_area_struct",
1431 sizeof(struct vm_area_struct), 0,
1433 mm_cachep = kmem_cache_create("mm_struct",
1434 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1435 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1439 * Check constraints on flags passed to the unshare system call and
1440 * force unsharing of additional process context as appropriate.
1442 static void check_unshare_flags(unsigned long *flags_ptr)
1445 * If unsharing a thread from a thread group, must also
1448 if (*flags_ptr & CLONE_THREAD)
1449 *flags_ptr |= CLONE_VM;
1452 * If unsharing vm, must also unshare signal handlers.
1454 if (*flags_ptr & CLONE_VM)
1455 *flags_ptr |= CLONE_SIGHAND;
1458 * If unsharing signal handlers and the task was created
1459 * using CLONE_THREAD, then must unshare the thread
1461 if ((*flags_ptr & CLONE_SIGHAND) &&
1462 (atomic_read(¤t->signal->count) > 1))
1463 *flags_ptr |= CLONE_THREAD;
1466 * If unsharing namespace, must also unshare filesystem information.
1468 if (*flags_ptr & CLONE_NEWNS)
1469 *flags_ptr |= CLONE_FS;
1473 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1475 static int unshare_thread(unsigned long unshare_flags)
1477 if (unshare_flags & CLONE_THREAD)
1484 * Unshare the filesystem structure if it is being shared
1486 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1488 struct fs_struct *fs = current->fs;
1490 if ((unshare_flags & CLONE_FS) &&
1491 (fs && atomic_read(&fs->count) > 1)) {
1492 *new_fsp = __copy_fs_struct(current->fs);
1501 * Unsharing of sighand is not supported yet
1503 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
1505 struct sighand_struct *sigh = current->sighand;
1507 if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)
1514 * Unshare vm if it is being shared
1516 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
1518 struct mm_struct *mm = current->mm;
1520 if ((unshare_flags & CLONE_VM) &&
1521 (mm && atomic_read(&mm->mm_users) > 1)) {
1529 * Unshare file descriptor table if it is being shared
1531 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1533 struct files_struct *fd = current->files;
1536 if ((unshare_flags & CLONE_FILES) &&
1537 (fd && atomic_read(&fd->count) > 1)) {
1538 *new_fdp = dup_fd(fd, &error);
1547 * unshare allows a process to 'unshare' part of the process
1548 * context which was originally shared using clone. copy_*
1549 * functions used by do_fork() cannot be used here directly
1550 * because they modify an inactive task_struct that is being
1551 * constructed. Here we are modifying the current, active,
1554 asmlinkage long sys_unshare(unsigned long unshare_flags)
1557 struct fs_struct *fs, *new_fs = NULL;
1558 struct sighand_struct *new_sigh = NULL;
1559 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
1560 struct files_struct *fd, *new_fd = NULL;
1561 struct nsproxy *new_nsproxy = NULL;
1564 check_unshare_flags(&unshare_flags);
1566 /* Return -EINVAL for all unsupported flags */
1568 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1569 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1570 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER|
1572 goto bad_unshare_out;
1575 * CLONE_NEWIPC must also detach from the undolist: after switching
1576 * to a new ipc namespace, the semaphore arrays from the old
1577 * namespace are unreachable.
1579 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1581 if ((err = unshare_thread(unshare_flags)))
1582 goto bad_unshare_out;
1583 if ((err = unshare_fs(unshare_flags, &new_fs)))
1584 goto bad_unshare_cleanup_thread;
1585 if ((err = unshare_sighand(unshare_flags, &new_sigh)))
1586 goto bad_unshare_cleanup_fs;
1587 if ((err = unshare_vm(unshare_flags, &new_mm)))
1588 goto bad_unshare_cleanup_sigh;
1589 if ((err = unshare_fd(unshare_flags, &new_fd)))
1590 goto bad_unshare_cleanup_vm;
1591 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
1593 goto bad_unshare_cleanup_fd;
1595 if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) {
1598 * CLONE_SYSVSEM is equivalent to sys_exit().
1604 switch_task_namespaces(current, new_nsproxy);
1612 current->fs = new_fs;
1618 active_mm = current->active_mm;
1619 current->mm = new_mm;
1620 current->active_mm = new_mm;
1621 activate_mm(active_mm, new_mm);
1626 fd = current->files;
1627 current->files = new_fd;
1631 task_unlock(current);
1635 put_nsproxy(new_nsproxy);
1637 bad_unshare_cleanup_fd:
1639 put_files_struct(new_fd);
1641 bad_unshare_cleanup_vm:
1645 bad_unshare_cleanup_sigh:
1647 if (atomic_dec_and_test(&new_sigh->count))
1648 kmem_cache_free(sighand_cachep, new_sigh);
1650 bad_unshare_cleanup_fs:
1652 put_fs_struct(new_fs);
1654 bad_unshare_cleanup_thread:
1660 * Helper to unshare the files of the current task.
1661 * We don't want to expose copy_files internals to
1662 * the exec layer of the kernel.
1665 int unshare_files(struct files_struct **displaced)
1667 struct task_struct *task = current;
1668 struct files_struct *copy = NULL;
1671 error = unshare_fd(CLONE_FILES, ©);
1672 if (error || !copy) {
1676 *displaced = task->files;