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/hugetlb.h>
37 #include <linux/swap.h>
38 #include <linux/syscalls.h>
39 #include <linux/jiffies.h>
40 #include <linux/futex.h>
41 #include <linux/task_io_accounting_ops.h>
42 #include <linux/rcupdate.h>
43 #include <linux/ptrace.h>
44 #include <linux/mount.h>
45 #include <linux/audit.h>
46 #include <linux/memcontrol.h>
47 #include <linux/profile.h>
48 #include <linux/rmap.h>
49 #include <linux/acct.h>
50 #include <linux/tsacct_kern.h>
51 #include <linux/cn_proc.h>
52 #include <linux/freezer.h>
53 #include <linux/delayacct.h>
54 #include <linux/taskstats_kern.h>
55 #include <linux/random.h>
56 #include <linux/tty.h>
57 #include <linux/proc_fs.h>
58 #include <linux/blkdev.h>
60 #include <asm/pgtable.h>
61 #include <asm/pgalloc.h>
62 #include <asm/uaccess.h>
63 #include <asm/mmu_context.h>
64 #include <asm/cacheflush.h>
65 #include <asm/tlbflush.h>
68 * Protected counters by write_lock_irq(&tasklist_lock)
70 unsigned long total_forks; /* Handle normal Linux uptimes. */
71 int nr_threads; /* The idle threads do not count.. */
73 int max_threads; /* tunable limit on nr_threads */
75 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
77 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
79 int nr_processes(void)
84 for_each_online_cpu(cpu)
85 total += per_cpu(process_counts, cpu);
90 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
91 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
92 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
93 static struct kmem_cache *task_struct_cachep;
96 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
97 static inline struct thread_info *alloc_thread_info(struct task_struct *tsk)
99 #ifdef CONFIG_DEBUG_STACK_USAGE
100 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
102 gfp_t mask = GFP_KERNEL;
104 return (struct thread_info *)__get_free_pages(mask, THREAD_SIZE_ORDER);
107 static inline void free_thread_info(struct thread_info *ti)
109 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
113 /* SLAB cache for signal_struct structures (tsk->signal) */
114 static struct kmem_cache *signal_cachep;
116 /* SLAB cache for sighand_struct structures (tsk->sighand) */
117 struct kmem_cache *sighand_cachep;
119 /* SLAB cache for files_struct structures (tsk->files) */
120 struct kmem_cache *files_cachep;
122 /* SLAB cache for fs_struct structures (tsk->fs) */
123 struct kmem_cache *fs_cachep;
125 /* SLAB cache for vm_area_struct structures */
126 struct kmem_cache *vm_area_cachep;
128 /* SLAB cache for mm_struct structures (tsk->mm) */
129 static struct kmem_cache *mm_cachep;
131 void free_task(struct task_struct *tsk)
133 prop_local_destroy_single(&tsk->dirties);
134 free_thread_info(tsk->stack);
135 rt_mutex_debug_task_free(tsk);
136 free_task_struct(tsk);
138 EXPORT_SYMBOL(free_task);
140 void __put_task_struct(struct task_struct *tsk)
142 WARN_ON(!tsk->exit_state);
143 WARN_ON(atomic_read(&tsk->usage));
144 WARN_ON(tsk == current);
146 security_task_free(tsk);
148 put_group_info(tsk->group_info);
149 delayacct_tsk_free(tsk);
151 if (!profile_handoff_task(tsk))
156 * macro override instead of weak attribute alias, to workaround
157 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
159 #ifndef arch_task_cache_init
160 #define arch_task_cache_init()
163 void __init fork_init(unsigned long mempages)
165 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
166 #ifndef ARCH_MIN_TASKALIGN
167 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
169 /* create a slab on which task_structs can be allocated */
171 kmem_cache_create("task_struct", sizeof(struct task_struct),
172 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL);
175 /* do the arch specific task caches init */
176 arch_task_cache_init();
179 * The default maximum number of threads is set to a safe
180 * value: the thread structures can take up at most half
183 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
186 * we need to allow at least 20 threads to boot a system
191 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
192 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
193 init_task.signal->rlim[RLIMIT_SIGPENDING] =
194 init_task.signal->rlim[RLIMIT_NPROC];
197 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
198 struct task_struct *src)
204 static struct task_struct *dup_task_struct(struct task_struct *orig)
206 struct task_struct *tsk;
207 struct thread_info *ti;
210 prepare_to_copy(orig);
212 tsk = alloc_task_struct();
216 ti = alloc_thread_info(tsk);
218 free_task_struct(tsk);
222 err = arch_dup_task_struct(tsk, orig);
228 err = prop_local_init_single(&tsk->dirties);
232 setup_thread_stack(tsk, orig);
234 #ifdef CONFIG_CC_STACKPROTECTOR
235 tsk->stack_canary = get_random_int();
238 /* One for us, one for whoever does the "release_task()" (usually parent) */
239 atomic_set(&tsk->usage,2);
240 atomic_set(&tsk->fs_excl, 0);
241 #ifdef CONFIG_BLK_DEV_IO_TRACE
244 tsk->splice_pipe = NULL;
248 free_thread_info(ti);
249 free_task_struct(tsk);
254 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
256 struct vm_area_struct *mpnt, *tmp, **pprev;
257 struct rb_node **rb_link, *rb_parent;
259 unsigned long charge;
260 struct mempolicy *pol;
262 down_write(&oldmm->mmap_sem);
263 flush_cache_dup_mm(oldmm);
265 * Not linked in yet - no deadlock potential:
267 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
271 mm->mmap_cache = NULL;
272 mm->free_area_cache = oldmm->mmap_base;
273 mm->cached_hole_size = ~0UL;
275 cpus_clear(mm->cpu_vm_mask);
277 rb_link = &mm->mm_rb.rb_node;
281 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
284 if (mpnt->vm_flags & VM_DONTCOPY) {
285 long pages = vma_pages(mpnt);
286 mm->total_vm -= pages;
287 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
292 if (mpnt->vm_flags & VM_ACCOUNT) {
293 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
294 if (security_vm_enough_memory(len))
298 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
302 pol = mpol_dup(vma_policy(mpnt));
303 retval = PTR_ERR(pol);
305 goto fail_nomem_policy;
306 vma_set_policy(tmp, pol);
307 tmp->vm_flags &= ~VM_LOCKED;
313 struct inode *inode = file->f_path.dentry->d_inode;
315 if (tmp->vm_flags & VM_DENYWRITE)
316 atomic_dec(&inode->i_writecount);
318 /* insert tmp into the share list, just after mpnt */
319 spin_lock(&file->f_mapping->i_mmap_lock);
320 tmp->vm_truncate_count = mpnt->vm_truncate_count;
321 flush_dcache_mmap_lock(file->f_mapping);
322 vma_prio_tree_add(tmp, mpnt);
323 flush_dcache_mmap_unlock(file->f_mapping);
324 spin_unlock(&file->f_mapping->i_mmap_lock);
328 * Clear hugetlb-related page reserves for children. This only
329 * affects MAP_PRIVATE mappings. Faults generated by the child
330 * are not guaranteed to succeed, even if read-only
332 if (is_vm_hugetlb_page(tmp))
333 reset_vma_resv_huge_pages(tmp);
336 * Link in the new vma and copy the page table entries.
339 pprev = &tmp->vm_next;
341 __vma_link_rb(mm, tmp, rb_link, rb_parent);
342 rb_link = &tmp->vm_rb.rb_right;
343 rb_parent = &tmp->vm_rb;
346 retval = copy_page_range(mm, oldmm, mpnt);
348 if (tmp->vm_ops && tmp->vm_ops->open)
349 tmp->vm_ops->open(tmp);
354 /* a new mm has just been created */
355 arch_dup_mmap(oldmm, mm);
358 up_write(&mm->mmap_sem);
360 up_write(&oldmm->mmap_sem);
363 kmem_cache_free(vm_area_cachep, tmp);
366 vm_unacct_memory(charge);
370 static inline int mm_alloc_pgd(struct mm_struct * mm)
372 mm->pgd = pgd_alloc(mm);
373 if (unlikely(!mm->pgd))
378 static inline void mm_free_pgd(struct mm_struct * mm)
380 pgd_free(mm, mm->pgd);
383 #define dup_mmap(mm, oldmm) (0)
384 #define mm_alloc_pgd(mm) (0)
385 #define mm_free_pgd(mm)
386 #endif /* CONFIG_MMU */
388 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
390 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
391 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
393 #include <linux/init_task.h>
395 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
397 atomic_set(&mm->mm_users, 1);
398 atomic_set(&mm->mm_count, 1);
399 init_rwsem(&mm->mmap_sem);
400 INIT_LIST_HEAD(&mm->mmlist);
401 mm->flags = (current->mm) ? current->mm->flags
402 : MMF_DUMP_FILTER_DEFAULT;
403 mm->core_waiters = 0;
405 set_mm_counter(mm, file_rss, 0);
406 set_mm_counter(mm, anon_rss, 0);
407 spin_lock_init(&mm->page_table_lock);
408 rwlock_init(&mm->ioctx_list_lock);
409 mm->ioctx_list = NULL;
410 mm->free_area_cache = TASK_UNMAPPED_BASE;
411 mm->cached_hole_size = ~0UL;
412 mm_init_owner(mm, p);
414 if (likely(!mm_alloc_pgd(mm))) {
424 * Allocate and initialize an mm_struct.
426 struct mm_struct * mm_alloc(void)
428 struct mm_struct * mm;
432 memset(mm, 0, sizeof(*mm));
433 mm = mm_init(mm, current);
439 * Called when the last reference to the mm
440 * is dropped: either by a lazy thread or by
441 * mmput. Free the page directory and the mm.
443 void __mmdrop(struct mm_struct *mm)
445 BUG_ON(mm == &init_mm);
450 EXPORT_SYMBOL_GPL(__mmdrop);
453 * Decrement the use count and release all resources for an mm.
455 void mmput(struct mm_struct *mm)
459 if (atomic_dec_and_test(&mm->mm_users)) {
462 set_mm_exe_file(mm, NULL);
463 if (!list_empty(&mm->mmlist)) {
464 spin_lock(&mmlist_lock);
465 list_del(&mm->mmlist);
466 spin_unlock(&mmlist_lock);
472 EXPORT_SYMBOL_GPL(mmput);
475 * get_task_mm - acquire a reference to the task's mm
477 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
478 * this kernel workthread has transiently adopted a user mm with use_mm,
479 * to do its AIO) is not set and if so returns a reference to it, after
480 * bumping up the use count. User must release the mm via mmput()
481 * after use. Typically used by /proc and ptrace.
483 struct mm_struct *get_task_mm(struct task_struct *task)
485 struct mm_struct *mm;
490 if (task->flags & PF_BORROWED_MM)
493 atomic_inc(&mm->mm_users);
498 EXPORT_SYMBOL_GPL(get_task_mm);
500 /* Please note the differences between mmput and mm_release.
501 * mmput is called whenever we stop holding onto a mm_struct,
502 * error success whatever.
504 * mm_release is called after a mm_struct has been removed
505 * from the current process.
507 * This difference is important for error handling, when we
508 * only half set up a mm_struct for a new process and need to restore
509 * the old one. Because we mmput the new mm_struct before
510 * restoring the old one. . .
511 * Eric Biederman 10 January 1998
513 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
515 struct completion *vfork_done = tsk->vfork_done;
517 /* Get rid of any cached register state */
518 deactivate_mm(tsk, mm);
520 /* notify parent sleeping on vfork() */
522 tsk->vfork_done = NULL;
523 complete(vfork_done);
527 * If we're exiting normally, clear a user-space tid field if
528 * requested. We leave this alone when dying by signal, to leave
529 * the value intact in a core dump, and to save the unnecessary
530 * trouble otherwise. Userland only wants this done for a sys_exit.
532 if (tsk->clear_child_tid
533 && !(tsk->flags & PF_SIGNALED)
534 && atomic_read(&mm->mm_users) > 1) {
535 u32 __user * tidptr = tsk->clear_child_tid;
536 tsk->clear_child_tid = NULL;
539 * We don't check the error code - if userspace has
540 * not set up a proper pointer then tough luck.
543 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
548 * Allocate a new mm structure and copy contents from the
549 * mm structure of the passed in task structure.
551 struct mm_struct *dup_mm(struct task_struct *tsk)
553 struct mm_struct *mm, *oldmm = current->mm;
563 memcpy(mm, oldmm, sizeof(*mm));
565 /* Initializing for Swap token stuff */
566 mm->token_priority = 0;
567 mm->last_interval = 0;
569 if (!mm_init(mm, tsk))
572 if (init_new_context(tsk, mm))
575 dup_mm_exe_file(oldmm, mm);
577 err = dup_mmap(mm, oldmm);
581 mm->hiwater_rss = get_mm_rss(mm);
582 mm->hiwater_vm = mm->total_vm;
594 * If init_new_context() failed, we cannot use mmput() to free the mm
595 * because it calls destroy_context()
602 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
604 struct mm_struct * mm, *oldmm;
607 tsk->min_flt = tsk->maj_flt = 0;
608 tsk->nvcsw = tsk->nivcsw = 0;
611 tsk->active_mm = NULL;
614 * Are we cloning a kernel thread?
616 * We need to steal a active VM for that..
622 if (clone_flags & CLONE_VM) {
623 atomic_inc(&oldmm->mm_users);
634 /* Initializing for Swap token stuff */
635 mm->token_priority = 0;
636 mm->last_interval = 0;
646 static struct fs_struct *__copy_fs_struct(struct fs_struct *old)
648 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
649 /* We don't need to lock fs - think why ;-) */
651 atomic_set(&fs->count, 1);
652 rwlock_init(&fs->lock);
653 fs->umask = old->umask;
654 read_lock(&old->lock);
655 fs->root = old->root;
656 path_get(&old->root);
659 if (old->altroot.dentry) {
660 fs->altroot = old->altroot;
661 path_get(&old->altroot);
663 fs->altroot.mnt = NULL;
664 fs->altroot.dentry = NULL;
666 read_unlock(&old->lock);
671 struct fs_struct *copy_fs_struct(struct fs_struct *old)
673 return __copy_fs_struct(old);
676 EXPORT_SYMBOL_GPL(copy_fs_struct);
678 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
680 if (clone_flags & CLONE_FS) {
681 atomic_inc(¤t->fs->count);
684 tsk->fs = __copy_fs_struct(current->fs);
690 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
692 struct files_struct *oldf, *newf;
696 * A background process may not have any files ...
698 oldf = current->files;
702 if (clone_flags & CLONE_FILES) {
703 atomic_inc(&oldf->count);
707 newf = dup_fd(oldf, &error);
717 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
720 struct io_context *ioc = current->io_context;
725 * Share io context with parent, if CLONE_IO is set
727 if (clone_flags & CLONE_IO) {
728 tsk->io_context = ioc_task_link(ioc);
729 if (unlikely(!tsk->io_context))
731 } else if (ioprio_valid(ioc->ioprio)) {
732 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
733 if (unlikely(!tsk->io_context))
736 tsk->io_context->ioprio = ioc->ioprio;
742 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
744 struct sighand_struct *sig;
746 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
747 atomic_inc(¤t->sighand->count);
750 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
751 rcu_assign_pointer(tsk->sighand, sig);
754 atomic_set(&sig->count, 1);
755 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
759 void __cleanup_sighand(struct sighand_struct *sighand)
761 if (atomic_dec_and_test(&sighand->count))
762 kmem_cache_free(sighand_cachep, sighand);
765 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
767 struct signal_struct *sig;
770 if (clone_flags & CLONE_THREAD) {
771 atomic_inc(¤t->signal->count);
772 atomic_inc(¤t->signal->live);
775 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
780 ret = copy_thread_group_keys(tsk);
782 kmem_cache_free(signal_cachep, sig);
786 atomic_set(&sig->count, 1);
787 atomic_set(&sig->live, 1);
788 init_waitqueue_head(&sig->wait_chldexit);
790 sig->group_exit_code = 0;
791 sig->group_exit_task = NULL;
792 sig->group_stop_count = 0;
793 sig->curr_target = tsk;
794 init_sigpending(&sig->shared_pending);
795 INIT_LIST_HEAD(&sig->posix_timers);
797 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
798 sig->it_real_incr.tv64 = 0;
799 sig->real_timer.function = it_real_fn;
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->leader = 0; /* session leadership doesn't inherit */
807 sig->tty_old_pgrp = NULL;
809 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
810 sig->gtime = cputime_zero;
811 sig->cgtime = cputime_zero;
812 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
813 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
814 sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
815 sig->sum_sched_runtime = 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]);
819 taskstats_tgid_init(sig);
821 task_lock(current->group_leader);
822 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
823 task_unlock(current->group_leader);
825 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
827 * New sole thread in the process gets an expiry time
828 * of the whole CPU time limit.
830 tsk->it_prof_expires =
831 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
833 acct_init_pacct(&sig->pacct);
840 void __cleanup_signal(struct signal_struct *sig)
842 exit_thread_group_keys(sig);
843 kmem_cache_free(signal_cachep, sig);
846 static void cleanup_signal(struct task_struct *tsk)
848 struct signal_struct *sig = tsk->signal;
850 atomic_dec(&sig->live);
852 if (atomic_dec_and_test(&sig->count))
853 __cleanup_signal(sig);
856 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
858 unsigned long new_flags = p->flags;
860 new_flags &= ~PF_SUPERPRIV;
861 new_flags |= PF_FORKNOEXEC;
862 if (!(clone_flags & CLONE_PTRACE))
864 p->flags = new_flags;
865 clear_freeze_flag(p);
868 asmlinkage long sys_set_tid_address(int __user *tidptr)
870 current->clear_child_tid = tidptr;
872 return task_pid_vnr(current);
875 static void rt_mutex_init_task(struct task_struct *p)
877 spin_lock_init(&p->pi_lock);
878 #ifdef CONFIG_RT_MUTEXES
879 plist_head_init(&p->pi_waiters, &p->pi_lock);
880 p->pi_blocked_on = NULL;
884 #ifdef CONFIG_MM_OWNER
885 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
889 #endif /* CONFIG_MM_OWNER */
892 * This creates a new process as a copy of the old one,
893 * but does not actually start it yet.
895 * It copies the registers, and all the appropriate
896 * parts of the process environment (as per the clone
897 * flags). The actual kick-off is left to the caller.
899 static struct task_struct *copy_process(unsigned long clone_flags,
900 unsigned long stack_start,
901 struct pt_regs *regs,
902 unsigned long stack_size,
903 int __user *child_tidptr,
907 struct task_struct *p;
908 int cgroup_callbacks_done = 0;
910 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
911 return ERR_PTR(-EINVAL);
914 * Thread groups must share signals as well, and detached threads
915 * can only be started up within the thread group.
917 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
918 return ERR_PTR(-EINVAL);
921 * Shared signal handlers imply shared VM. By way of the above,
922 * thread groups also imply shared VM. Blocking this case allows
923 * for various simplifications in other code.
925 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
926 return ERR_PTR(-EINVAL);
928 retval = security_task_create(clone_flags);
933 p = dup_task_struct(current);
937 rt_mutex_init_task(p);
939 #ifdef CONFIG_PROVE_LOCKING
940 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
941 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
944 if (atomic_read(&p->user->processes) >=
945 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
946 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
947 p->user != current->nsproxy->user_ns->root_user)
951 atomic_inc(&p->user->__count);
952 atomic_inc(&p->user->processes);
953 get_group_info(p->group_info);
956 * If multiple threads are within copy_process(), then this check
957 * triggers too late. This doesn't hurt, the check is only there
958 * to stop root fork bombs.
960 if (nr_threads >= max_threads)
961 goto bad_fork_cleanup_count;
963 if (!try_module_get(task_thread_info(p)->exec_domain->module))
964 goto bad_fork_cleanup_count;
966 if (p->binfmt && !try_module_get(p->binfmt->module))
967 goto bad_fork_cleanup_put_domain;
970 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
971 copy_flags(clone_flags, p);
972 INIT_LIST_HEAD(&p->children);
973 INIT_LIST_HEAD(&p->sibling);
974 #ifdef CONFIG_PREEMPT_RCU
975 p->rcu_read_lock_nesting = 0;
976 p->rcu_flipctr_idx = 0;
977 #endif /* #ifdef CONFIG_PREEMPT_RCU */
978 p->vfork_done = NULL;
979 spin_lock_init(&p->alloc_lock);
981 clear_tsk_thread_flag(p, TIF_SIGPENDING);
982 init_sigpending(&p->pending);
984 p->utime = cputime_zero;
985 p->stime = cputime_zero;
986 p->gtime = cputime_zero;
987 p->utimescaled = cputime_zero;
988 p->stimescaled = cputime_zero;
989 p->prev_utime = cputime_zero;
990 p->prev_stime = cputime_zero;
992 #ifdef CONFIG_DETECT_SOFTLOCKUP
993 p->last_switch_count = 0;
994 p->last_switch_timestamp = 0;
997 #ifdef CONFIG_TASK_XACCT
998 p->rchar = 0; /* I/O counter: bytes read */
999 p->wchar = 0; /* I/O counter: bytes written */
1000 p->syscr = 0; /* I/O counter: read syscalls */
1001 p->syscw = 0; /* I/O counter: write syscalls */
1003 task_io_accounting_init(p);
1004 acct_clear_integrals(p);
1006 p->it_virt_expires = cputime_zero;
1007 p->it_prof_expires = cputime_zero;
1008 p->it_sched_expires = 0;
1009 INIT_LIST_HEAD(&p->cpu_timers[0]);
1010 INIT_LIST_HEAD(&p->cpu_timers[1]);
1011 INIT_LIST_HEAD(&p->cpu_timers[2]);
1013 p->lock_depth = -1; /* -1 = no lock */
1014 do_posix_clock_monotonic_gettime(&p->start_time);
1015 p->real_start_time = p->start_time;
1016 monotonic_to_bootbased(&p->real_start_time);
1017 #ifdef CONFIG_SECURITY
1020 p->cap_bset = current->cap_bset;
1021 p->io_context = NULL;
1022 p->audit_context = NULL;
1025 p->mempolicy = mpol_dup(p->mempolicy);
1026 if (IS_ERR(p->mempolicy)) {
1027 retval = PTR_ERR(p->mempolicy);
1028 p->mempolicy = NULL;
1029 goto bad_fork_cleanup_cgroup;
1031 mpol_fix_fork_child_flag(p);
1033 #ifdef CONFIG_TRACE_IRQFLAGS
1035 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1036 p->hardirqs_enabled = 1;
1038 p->hardirqs_enabled = 0;
1040 p->hardirq_enable_ip = 0;
1041 p->hardirq_enable_event = 0;
1042 p->hardirq_disable_ip = _THIS_IP_;
1043 p->hardirq_disable_event = 0;
1044 p->softirqs_enabled = 1;
1045 p->softirq_enable_ip = _THIS_IP_;
1046 p->softirq_enable_event = 0;
1047 p->softirq_disable_ip = 0;
1048 p->softirq_disable_event = 0;
1049 p->hardirq_context = 0;
1050 p->softirq_context = 0;
1052 #ifdef CONFIG_LOCKDEP
1053 p->lockdep_depth = 0; /* no locks held yet */
1054 p->curr_chain_key = 0;
1055 p->lockdep_recursion = 0;
1058 #ifdef CONFIG_DEBUG_MUTEXES
1059 p->blocked_on = NULL; /* not blocked yet */
1062 /* Perform scheduler related setup. Assign this task to a CPU. */
1063 sched_fork(p, clone_flags);
1065 if ((retval = security_task_alloc(p)))
1066 goto bad_fork_cleanup_policy;
1067 if ((retval = audit_alloc(p)))
1068 goto bad_fork_cleanup_security;
1069 /* copy all the process information */
1070 if ((retval = copy_semundo(clone_flags, p)))
1071 goto bad_fork_cleanup_audit;
1072 if ((retval = copy_files(clone_flags, p)))
1073 goto bad_fork_cleanup_semundo;
1074 if ((retval = copy_fs(clone_flags, p)))
1075 goto bad_fork_cleanup_files;
1076 if ((retval = copy_sighand(clone_flags, p)))
1077 goto bad_fork_cleanup_fs;
1078 if ((retval = copy_signal(clone_flags, p)))
1079 goto bad_fork_cleanup_sighand;
1080 if ((retval = copy_mm(clone_flags, p)))
1081 goto bad_fork_cleanup_signal;
1082 if ((retval = copy_keys(clone_flags, p)))
1083 goto bad_fork_cleanup_mm;
1084 if ((retval = copy_namespaces(clone_flags, p)))
1085 goto bad_fork_cleanup_keys;
1086 if ((retval = copy_io(clone_flags, p)))
1087 goto bad_fork_cleanup_namespaces;
1088 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1090 goto bad_fork_cleanup_io;
1092 if (pid != &init_struct_pid) {
1094 pid = alloc_pid(task_active_pid_ns(p));
1096 goto bad_fork_cleanup_io;
1098 if (clone_flags & CLONE_NEWPID) {
1099 retval = pid_ns_prepare_proc(task_active_pid_ns(p));
1101 goto bad_fork_free_pid;
1105 p->pid = pid_nr(pid);
1107 if (clone_flags & CLONE_THREAD)
1108 p->tgid = current->tgid;
1110 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1112 * Clear TID on mm_release()?
1114 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1116 p->robust_list = NULL;
1117 #ifdef CONFIG_COMPAT
1118 p->compat_robust_list = NULL;
1120 INIT_LIST_HEAD(&p->pi_state_list);
1121 p->pi_state_cache = NULL;
1124 * sigaltstack should be cleared when sharing the same VM
1126 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1127 p->sas_ss_sp = p->sas_ss_size = 0;
1130 * Syscall tracing should be turned off in the child regardless
1133 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1134 #ifdef TIF_SYSCALL_EMU
1135 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1137 clear_all_latency_tracing(p);
1139 /* Our parent execution domain becomes current domain
1140 These must match for thread signalling to apply */
1141 p->parent_exec_id = p->self_exec_id;
1143 /* ok, now we should be set up.. */
1144 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1145 p->pdeath_signal = 0;
1149 * Ok, make it visible to the rest of the system.
1150 * We dont wake it up yet.
1152 p->group_leader = p;
1153 INIT_LIST_HEAD(&p->thread_group);
1154 INIT_LIST_HEAD(&p->ptrace_entry);
1155 INIT_LIST_HEAD(&p->ptraced);
1157 /* Now that the task is set up, run cgroup callbacks if
1158 * necessary. We need to run them before the task is visible
1159 * on the tasklist. */
1160 cgroup_fork_callbacks(p);
1161 cgroup_callbacks_done = 1;
1163 /* Need tasklist lock for parent etc handling! */
1164 write_lock_irq(&tasklist_lock);
1167 * The task hasn't been attached yet, so its cpus_allowed mask will
1168 * not be changed, nor will its assigned CPU.
1170 * The cpus_allowed mask of the parent may have changed after it was
1171 * copied first time - so re-copy it here, then check the child's CPU
1172 * to ensure it is on a valid CPU (and if not, just force it back to
1173 * parent's CPU). This avoids alot of nasty races.
1175 p->cpus_allowed = current->cpus_allowed;
1176 p->rt.nr_cpus_allowed = current->rt.nr_cpus_allowed;
1177 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1178 !cpu_online(task_cpu(p))))
1179 set_task_cpu(p, smp_processor_id());
1181 /* CLONE_PARENT re-uses the old parent */
1182 if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1183 p->real_parent = current->real_parent;
1185 p->real_parent = current;
1186 p->parent = p->real_parent;
1188 spin_lock(¤t->sighand->siglock);
1191 * Process group and session signals need to be delivered to just the
1192 * parent before the fork or both the parent and the child after the
1193 * fork. Restart if a signal comes in before we add the new process to
1194 * it's process group.
1195 * A fatal signal pending means that current will exit, so the new
1196 * thread can't slip out of an OOM kill (or normal SIGKILL).
1198 recalc_sigpending();
1199 if (signal_pending(current)) {
1200 spin_unlock(¤t->sighand->siglock);
1201 write_unlock_irq(&tasklist_lock);
1202 retval = -ERESTARTNOINTR;
1203 goto bad_fork_free_pid;
1206 if (clone_flags & CLONE_THREAD) {
1207 p->group_leader = current->group_leader;
1208 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1210 if (!cputime_eq(current->signal->it_virt_expires,
1212 !cputime_eq(current->signal->it_prof_expires,
1214 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1215 !list_empty(¤t->signal->cpu_timers[0]) ||
1216 !list_empty(¤t->signal->cpu_timers[1]) ||
1217 !list_empty(¤t->signal->cpu_timers[2])) {
1219 * Have child wake up on its first tick to check
1220 * for process CPU timers.
1222 p->it_prof_expires = jiffies_to_cputime(1);
1226 if (likely(p->pid)) {
1227 list_add_tail(&p->sibling, &p->real_parent->children);
1228 if (unlikely(p->ptrace & PT_PTRACED))
1229 __ptrace_link(p, current->parent);
1231 if (thread_group_leader(p)) {
1232 if (clone_flags & CLONE_NEWPID)
1233 p->nsproxy->pid_ns->child_reaper = p;
1235 p->signal->leader_pid = pid;
1236 p->signal->tty = current->signal->tty;
1237 set_task_pgrp(p, task_pgrp_nr(current));
1238 set_task_session(p, task_session_nr(current));
1239 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1240 attach_pid(p, PIDTYPE_SID, task_session(current));
1241 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1242 __get_cpu_var(process_counts)++;
1244 attach_pid(p, PIDTYPE_PID, pid);
1249 spin_unlock(¤t->sighand->siglock);
1250 write_unlock_irq(&tasklist_lock);
1251 proc_fork_connector(p);
1252 cgroup_post_fork(p);
1256 if (pid != &init_struct_pid)
1258 bad_fork_cleanup_io:
1259 put_io_context(p->io_context);
1260 bad_fork_cleanup_namespaces:
1261 exit_task_namespaces(p);
1262 bad_fork_cleanup_keys:
1264 bad_fork_cleanup_mm:
1267 bad_fork_cleanup_signal:
1269 bad_fork_cleanup_sighand:
1270 __cleanup_sighand(p->sighand);
1271 bad_fork_cleanup_fs:
1272 exit_fs(p); /* blocking */
1273 bad_fork_cleanup_files:
1274 exit_files(p); /* blocking */
1275 bad_fork_cleanup_semundo:
1277 bad_fork_cleanup_audit:
1279 bad_fork_cleanup_security:
1280 security_task_free(p);
1281 bad_fork_cleanup_policy:
1283 mpol_put(p->mempolicy);
1284 bad_fork_cleanup_cgroup:
1286 cgroup_exit(p, cgroup_callbacks_done);
1287 delayacct_tsk_free(p);
1289 module_put(p->binfmt->module);
1290 bad_fork_cleanup_put_domain:
1291 module_put(task_thread_info(p)->exec_domain->module);
1292 bad_fork_cleanup_count:
1293 put_group_info(p->group_info);
1294 atomic_dec(&p->user->processes);
1299 return ERR_PTR(retval);
1302 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1304 memset(regs, 0, sizeof(struct pt_regs));
1308 struct task_struct * __cpuinit fork_idle(int cpu)
1310 struct task_struct *task;
1311 struct pt_regs regs;
1313 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL,
1316 init_idle(task, cpu);
1321 static int fork_traceflag(unsigned clone_flags)
1323 if (clone_flags & CLONE_UNTRACED)
1325 else if (clone_flags & CLONE_VFORK) {
1326 if (current->ptrace & PT_TRACE_VFORK)
1327 return PTRACE_EVENT_VFORK;
1328 } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1329 if (current->ptrace & PT_TRACE_CLONE)
1330 return PTRACE_EVENT_CLONE;
1331 } else if (current->ptrace & PT_TRACE_FORK)
1332 return PTRACE_EVENT_FORK;
1338 * Ok, this is the main fork-routine.
1340 * It copies the process, and if successful kick-starts
1341 * it and waits for it to finish using the VM if required.
1343 long do_fork(unsigned long clone_flags,
1344 unsigned long stack_start,
1345 struct pt_regs *regs,
1346 unsigned long stack_size,
1347 int __user *parent_tidptr,
1348 int __user *child_tidptr)
1350 struct task_struct *p;
1355 * We hope to recycle these flags after 2.6.26
1357 if (unlikely(clone_flags & CLONE_STOPPED)) {
1358 static int __read_mostly count = 100;
1360 if (count > 0 && printk_ratelimit()) {
1361 char comm[TASK_COMM_LEN];
1364 printk(KERN_INFO "fork(): process `%s' used deprecated "
1365 "clone flags 0x%lx\n",
1366 get_task_comm(comm, current),
1367 clone_flags & CLONE_STOPPED);
1371 if (unlikely(current->ptrace)) {
1372 trace = fork_traceflag (clone_flags);
1374 clone_flags |= CLONE_PTRACE;
1377 p = copy_process(clone_flags, stack_start, regs, stack_size,
1378 child_tidptr, NULL);
1380 * Do this prior waking up the new thread - the thread pointer
1381 * might get invalid after that point, if the thread exits quickly.
1384 struct completion vfork;
1386 nr = task_pid_vnr(p);
1388 if (clone_flags & CLONE_PARENT_SETTID)
1389 put_user(nr, parent_tidptr);
1391 if (clone_flags & CLONE_VFORK) {
1392 p->vfork_done = &vfork;
1393 init_completion(&vfork);
1396 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1398 * We'll start up with an immediate SIGSTOP.
1400 sigaddset(&p->pending.signal, SIGSTOP);
1401 set_tsk_thread_flag(p, TIF_SIGPENDING);
1404 if (!(clone_flags & CLONE_STOPPED))
1405 wake_up_new_task(p, clone_flags);
1407 __set_task_state(p, TASK_STOPPED);
1409 if (unlikely (trace)) {
1410 current->ptrace_message = nr;
1411 ptrace_notify ((trace << 8) | SIGTRAP);
1414 if (clone_flags & CLONE_VFORK) {
1415 freezer_do_not_count();
1416 wait_for_completion(&vfork);
1418 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE)) {
1419 current->ptrace_message = nr;
1420 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1429 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1430 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1433 static void sighand_ctor(struct kmem_cache *cachep, void *data)
1435 struct sighand_struct *sighand = data;
1437 spin_lock_init(&sighand->siglock);
1438 init_waitqueue_head(&sighand->signalfd_wqh);
1441 void __init proc_caches_init(void)
1443 sighand_cachep = kmem_cache_create("sighand_cache",
1444 sizeof(struct sighand_struct), 0,
1445 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
1447 signal_cachep = kmem_cache_create("signal_cache",
1448 sizeof(struct signal_struct), 0,
1449 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1450 files_cachep = kmem_cache_create("files_cache",
1451 sizeof(struct files_struct), 0,
1452 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1453 fs_cachep = kmem_cache_create("fs_cache",
1454 sizeof(struct fs_struct), 0,
1455 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1456 vm_area_cachep = kmem_cache_create("vm_area_struct",
1457 sizeof(struct vm_area_struct), 0,
1459 mm_cachep = kmem_cache_create("mm_struct",
1460 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1461 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
1465 * Check constraints on flags passed to the unshare system call and
1466 * force unsharing of additional process context as appropriate.
1468 static void check_unshare_flags(unsigned long *flags_ptr)
1471 * If unsharing a thread from a thread group, must also
1474 if (*flags_ptr & CLONE_THREAD)
1475 *flags_ptr |= CLONE_VM;
1478 * If unsharing vm, must also unshare signal handlers.
1480 if (*flags_ptr & CLONE_VM)
1481 *flags_ptr |= CLONE_SIGHAND;
1484 * If unsharing signal handlers and the task was created
1485 * using CLONE_THREAD, then must unshare the thread
1487 if ((*flags_ptr & CLONE_SIGHAND) &&
1488 (atomic_read(¤t->signal->count) > 1))
1489 *flags_ptr |= CLONE_THREAD;
1492 * If unsharing namespace, must also unshare filesystem information.
1494 if (*flags_ptr & CLONE_NEWNS)
1495 *flags_ptr |= CLONE_FS;
1499 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1501 static int unshare_thread(unsigned long unshare_flags)
1503 if (unshare_flags & CLONE_THREAD)
1510 * Unshare the filesystem structure if it is being shared
1512 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1514 struct fs_struct *fs = current->fs;
1516 if ((unshare_flags & CLONE_FS) &&
1517 (fs && atomic_read(&fs->count) > 1)) {
1518 *new_fsp = __copy_fs_struct(current->fs);
1527 * Unsharing of sighand is not supported yet
1529 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
1531 struct sighand_struct *sigh = current->sighand;
1533 if ((unshare_flags & CLONE_SIGHAND) && atomic_read(&sigh->count) > 1)
1540 * Unshare vm if it is being shared
1542 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
1544 struct mm_struct *mm = current->mm;
1546 if ((unshare_flags & CLONE_VM) &&
1547 (mm && atomic_read(&mm->mm_users) > 1)) {
1555 * Unshare file descriptor table if it is being shared
1557 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1559 struct files_struct *fd = current->files;
1562 if ((unshare_flags & CLONE_FILES) &&
1563 (fd && atomic_read(&fd->count) > 1)) {
1564 *new_fdp = dup_fd(fd, &error);
1573 * unshare allows a process to 'unshare' part of the process
1574 * context which was originally shared using clone. copy_*
1575 * functions used by do_fork() cannot be used here directly
1576 * because they modify an inactive task_struct that is being
1577 * constructed. Here we are modifying the current, active,
1580 asmlinkage long sys_unshare(unsigned long unshare_flags)
1583 struct fs_struct *fs, *new_fs = NULL;
1584 struct sighand_struct *new_sigh = NULL;
1585 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
1586 struct files_struct *fd, *new_fd = NULL;
1587 struct nsproxy *new_nsproxy = NULL;
1590 check_unshare_flags(&unshare_flags);
1592 /* Return -EINVAL for all unsupported flags */
1594 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1595 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1596 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWUSER|
1598 goto bad_unshare_out;
1601 * CLONE_NEWIPC must also detach from the undolist: after switching
1602 * to a new ipc namespace, the semaphore arrays from the old
1603 * namespace are unreachable.
1605 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1607 if ((err = unshare_thread(unshare_flags)))
1608 goto bad_unshare_out;
1609 if ((err = unshare_fs(unshare_flags, &new_fs)))
1610 goto bad_unshare_cleanup_thread;
1611 if ((err = unshare_sighand(unshare_flags, &new_sigh)))
1612 goto bad_unshare_cleanup_fs;
1613 if ((err = unshare_vm(unshare_flags, &new_mm)))
1614 goto bad_unshare_cleanup_sigh;
1615 if ((err = unshare_fd(unshare_flags, &new_fd)))
1616 goto bad_unshare_cleanup_vm;
1617 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
1619 goto bad_unshare_cleanup_fd;
1621 if (new_fs || new_mm || new_fd || do_sysvsem || new_nsproxy) {
1624 * CLONE_SYSVSEM is equivalent to sys_exit().
1630 switch_task_namespaces(current, new_nsproxy);
1638 current->fs = new_fs;
1644 active_mm = current->active_mm;
1645 current->mm = new_mm;
1646 current->active_mm = new_mm;
1647 activate_mm(active_mm, new_mm);
1652 fd = current->files;
1653 current->files = new_fd;
1657 task_unlock(current);
1661 put_nsproxy(new_nsproxy);
1663 bad_unshare_cleanup_fd:
1665 put_files_struct(new_fd);
1667 bad_unshare_cleanup_vm:
1671 bad_unshare_cleanup_sigh:
1673 if (atomic_dec_and_test(&new_sigh->count))
1674 kmem_cache_free(sighand_cachep, new_sigh);
1676 bad_unshare_cleanup_fs:
1678 put_fs_struct(new_fs);
1680 bad_unshare_cleanup_thread:
1686 * Helper to unshare the files of the current task.
1687 * We don't want to expose copy_files internals to
1688 * the exec layer of the kernel.
1691 int unshare_files(struct files_struct **displaced)
1693 struct task_struct *task = current;
1694 struct files_struct *copy = NULL;
1697 error = unshare_fd(CLONE_FILES, ©);
1698 if (error || !copy) {
1702 *displaced = task->files;