4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
14 #include <linux/config.h>
15 #include <linux/slab.h>
16 #include <linux/init.h>
17 #include <linux/unistd.h>
18 #include <linux/smp_lock.h>
19 #include <linux/module.h>
20 #include <linux/vmalloc.h>
21 #include <linux/completion.h>
22 #include <linux/namespace.h>
23 #include <linux/personality.h>
24 #include <linux/mempolicy.h>
25 #include <linux/sem.h>
26 #include <linux/file.h>
27 #include <linux/key.h>
28 #include <linux/binfmts.h>
29 #include <linux/mman.h>
31 #include <linux/capability.h>
32 #include <linux/cpu.h>
33 #include <linux/cpuset.h>
34 #include <linux/security.h>
35 #include <linux/swap.h>
36 #include <linux/syscalls.h>
37 #include <linux/jiffies.h>
38 #include <linux/futex.h>
39 #include <linux/rcupdate.h>
40 #include <linux/ptrace.h>
41 #include <linux/mount.h>
42 #include <linux/audit.h>
43 #include <linux/profile.h>
44 #include <linux/rmap.h>
45 #include <linux/acct.h>
46 #include <linux/cn_proc.h>
47 #include <linux/vs_context.h>
48 #include <linux/vs_network.h>
49 #include <linux/vs_limit.h>
50 #include <linux/vs_memory.h>
52 #include <asm/pgtable.h>
53 #include <asm/pgalloc.h>
54 #include <asm/uaccess.h>
55 #include <asm/mmu_context.h>
56 #include <asm/cacheflush.h>
57 #include <asm/tlbflush.h>
60 * Protected counters by write_lock_irq(&tasklist_lock)
62 unsigned long total_forks; /* Handle normal Linux uptimes. */
63 int nr_threads; /* The idle threads do not count.. */
65 int max_threads; /* tunable limit on nr_threads */
67 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
69 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
71 EXPORT_SYMBOL(tasklist_lock);
73 int nr_processes(void)
78 for_each_online_cpu(cpu)
79 total += per_cpu(process_counts, cpu);
84 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
85 # define alloc_task_struct() kmem_cache_alloc(task_struct_cachep, GFP_KERNEL)
86 # define free_task_struct(tsk) kmem_cache_free(task_struct_cachep, (tsk))
87 static kmem_cache_t *task_struct_cachep;
90 /* SLAB cache for signal_struct structures (tsk->signal) */
91 static kmem_cache_t *signal_cachep;
93 /* SLAB cache for sighand_struct structures (tsk->sighand) */
94 kmem_cache_t *sighand_cachep;
96 /* SLAB cache for files_struct structures (tsk->files) */
97 kmem_cache_t *files_cachep;
99 /* SLAB cache for fs_struct structures (tsk->fs) */
100 kmem_cache_t *fs_cachep;
102 /* SLAB cache for vm_area_struct structures */
103 kmem_cache_t *vm_area_cachep;
105 /* SLAB cache for mm_struct structures (tsk->mm) */
106 static kmem_cache_t *mm_cachep;
108 void free_task(struct task_struct *tsk)
110 free_thread_info(tsk->thread_info);
111 clr_vx_info(&tsk->vx_info);
112 clr_nx_info(&tsk->nx_info);
113 free_task_struct(tsk);
115 EXPORT_SYMBOL(free_task);
117 void __put_task_struct(struct task_struct *tsk)
119 WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
120 WARN_ON(atomic_read(&tsk->usage));
121 WARN_ON(tsk == current);
123 security_task_free(tsk);
125 put_group_info(tsk->group_info);
127 if (!profile_handoff_task(tsk))
131 void __init fork_init(unsigned long mempages)
133 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
134 #ifndef ARCH_MIN_TASKALIGN
135 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
137 /* create a slab on which task_structs can be allocated */
139 kmem_cache_create("task_struct", sizeof(struct task_struct),
140 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
144 * The default maximum number of threads is set to a safe
145 * value: the thread structures can take up at most half
148 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
151 * we need to allow at least 20 threads to boot a system
156 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
157 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
158 init_task.signal->rlim[RLIMIT_SIGPENDING] =
159 init_task.signal->rlim[RLIMIT_NPROC];
162 static struct task_struct *dup_task_struct(struct task_struct *orig)
164 struct task_struct *tsk;
165 struct thread_info *ti;
167 prepare_to_copy(orig);
169 tsk = alloc_task_struct();
173 ti = alloc_thread_info(tsk);
175 free_task_struct(tsk);
180 tsk->thread_info = ti;
181 setup_thread_stack(tsk, orig);
183 /* One for us, one for whoever does the "release_task()" (usually parent) */
184 atomic_set(&tsk->usage,2);
185 atomic_set(&tsk->fs_excl, 0);
187 tsk->splice_pipe = NULL;
192 static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
194 struct vm_area_struct *mpnt, *tmp, **pprev;
195 struct rb_node **rb_link, *rb_parent;
197 unsigned long charge;
198 struct mempolicy *pol;
200 down_write(&oldmm->mmap_sem);
201 flush_cache_mm(oldmm);
202 down_write(&mm->mmap_sem);
206 mm->mmap_cache = NULL;
207 mm->free_area_cache = oldmm->mmap_base;
208 mm->cached_hole_size = ~0UL;
210 __set_mm_counter(mm, file_rss, 0);
211 __set_mm_counter(mm, anon_rss, 0);
212 cpus_clear(mm->cpu_vm_mask);
214 rb_link = &mm->mm_rb.rb_node;
218 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
221 if (mpnt->vm_flags & VM_DONTCOPY) {
222 long pages = vma_pages(mpnt);
223 vx_vmpages_sub(mm, pages);
224 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
229 if (mpnt->vm_flags & VM_ACCOUNT) {
230 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
231 if (security_vm_enough_memory(len))
235 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
239 pol = mpol_copy(vma_policy(mpnt));
240 retval = PTR_ERR(pol);
242 goto fail_nomem_policy;
243 vma_set_policy(tmp, pol);
244 tmp->vm_flags &= ~VM_LOCKED;
250 struct inode *inode = file->f_dentry->d_inode;
252 if (tmp->vm_flags & VM_DENYWRITE)
253 atomic_dec(&inode->i_writecount);
255 /* insert tmp into the share list, just after mpnt */
256 spin_lock(&file->f_mapping->i_mmap_lock);
257 tmp->vm_truncate_count = mpnt->vm_truncate_count;
258 flush_dcache_mmap_lock(file->f_mapping);
259 vma_prio_tree_add(tmp, mpnt);
260 flush_dcache_mmap_unlock(file->f_mapping);
261 spin_unlock(&file->f_mapping->i_mmap_lock);
265 * Link in the new vma and copy the page table entries.
268 pprev = &tmp->vm_next;
270 __vma_link_rb(mm, tmp, rb_link, rb_parent);
271 rb_link = &tmp->vm_rb.rb_right;
272 rb_parent = &tmp->vm_rb;
275 retval = copy_page_range(mm, oldmm, mpnt);
277 if (tmp->vm_ops && tmp->vm_ops->open)
278 tmp->vm_ops->open(tmp);
285 up_write(&mm->mmap_sem);
287 up_write(&oldmm->mmap_sem);
290 kmem_cache_free(vm_area_cachep, tmp);
293 vm_unacct_memory(charge);
297 static inline int mm_alloc_pgd(struct mm_struct * mm)
299 mm->pgd = pgd_alloc(mm);
300 if (unlikely(!mm->pgd))
305 static inline void mm_free_pgd(struct mm_struct * mm)
310 #define dup_mmap(mm, oldmm) (0)
311 #define mm_alloc_pgd(mm) (0)
312 #define mm_free_pgd(mm)
313 #endif /* CONFIG_MMU */
315 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
317 #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
318 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
320 #include <linux/init_task.h>
322 static struct mm_struct * mm_init(struct mm_struct * mm)
324 atomic_set(&mm->mm_users, 1);
325 atomic_set(&mm->mm_count, 1);
326 init_rwsem(&mm->mmap_sem);
327 INIT_LIST_HEAD(&mm->mmlist);
328 mm->core_waiters = 0;
330 spin_lock_init(&mm->page_table_lock);
331 rwlock_init(&mm->ioctx_list_lock);
332 mm->ioctx_list = NULL;
333 mm->free_area_cache = TASK_UNMAPPED_BASE;
334 mm->cached_hole_size = ~0UL;
336 if (likely(!mm_alloc_pgd(mm))) {
338 set_vx_info(&mm->mm_vx_info, current->vx_info);
346 * Allocate and initialize an mm_struct.
348 struct mm_struct * mm_alloc(void)
350 struct mm_struct * mm;
354 memset(mm, 0, sizeof(*mm));
361 * Called when the last reference to the mm
362 * is dropped: either by a lazy thread or by
363 * mmput. Free the page directory and the mm.
365 void fastcall __mmdrop(struct mm_struct *mm)
367 BUG_ON(mm == &init_mm);
370 clr_vx_info(&mm->mm_vx_info);
375 * Decrement the use count and release all resources for an mm.
377 void mmput(struct mm_struct *mm)
379 if (atomic_dec_and_test(&mm->mm_users)) {
382 if (!list_empty(&mm->mmlist)) {
383 spin_lock(&mmlist_lock);
384 list_del(&mm->mmlist);
385 spin_unlock(&mmlist_lock);
391 EXPORT_SYMBOL_GPL(mmput);
394 * get_task_mm - acquire a reference to the task's mm
396 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
397 * this kernel workthread has transiently adopted a user mm with use_mm,
398 * to do its AIO) is not set and if so returns a reference to it, after
399 * bumping up the use count. User must release the mm via mmput()
400 * after use. Typically used by /proc and ptrace.
402 struct mm_struct *get_task_mm(struct task_struct *task)
404 struct mm_struct *mm;
409 if (task->flags & PF_BORROWED_MM)
412 atomic_inc(&mm->mm_users);
417 EXPORT_SYMBOL_GPL(get_task_mm);
419 /* Please note the differences between mmput and mm_release.
420 * mmput is called whenever we stop holding onto a mm_struct,
421 * error success whatever.
423 * mm_release is called after a mm_struct has been removed
424 * from the current process.
426 * This difference is important for error handling, when we
427 * only half set up a mm_struct for a new process and need to restore
428 * the old one. Because we mmput the new mm_struct before
429 * restoring the old one. . .
430 * Eric Biederman 10 January 1998
432 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
434 struct completion *vfork_done = tsk->vfork_done;
436 /* Get rid of any cached register state */
437 deactivate_mm(tsk, mm);
439 /* notify parent sleeping on vfork() */
441 tsk->vfork_done = NULL;
442 complete(vfork_done);
444 if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
445 u32 __user * tidptr = tsk->clear_child_tid;
446 tsk->clear_child_tid = NULL;
449 * We don't check the error code - if userspace has
450 * not set up a proper pointer then tough luck.
453 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
458 * Allocate a new mm structure and copy contents from the
459 * mm structure of the passed in task structure.
461 static struct mm_struct *dup_mm(struct task_struct *tsk)
463 struct mm_struct *mm, *oldmm = current->mm;
473 memcpy(mm, oldmm, sizeof(*mm));
474 mm->mm_vx_info = NULL;
479 if (init_new_context(tsk, mm))
482 err = dup_mmap(mm, oldmm);
486 mm->hiwater_rss = get_mm_rss(mm);
487 mm->hiwater_vm = mm->total_vm;
499 * If init_new_context() failed, we cannot use mmput() to free the mm
500 * because it calls destroy_context()
502 clr_vx_info(&mm->mm_vx_info);
508 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
510 struct mm_struct * mm, *oldmm;
513 tsk->min_flt = tsk->maj_flt = 0;
514 tsk->nvcsw = tsk->nivcsw = 0;
517 tsk->active_mm = NULL;
520 * Are we cloning a kernel thread?
522 * We need to steal a active VM for that..
528 if (clone_flags & CLONE_VM) {
529 atomic_inc(&oldmm->mm_users);
548 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
550 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
551 /* We don't need to lock fs - think why ;-) */
553 atomic_set(&fs->count, 1);
554 rwlock_init(&fs->lock);
555 fs->umask = old->umask;
556 read_lock(&old->lock);
557 fs->rootmnt = mntget(old->rootmnt);
558 fs->root = dget(old->root);
559 fs->pwdmnt = mntget(old->pwdmnt);
560 fs->pwd = dget(old->pwd);
562 fs->altrootmnt = mntget(old->altrootmnt);
563 fs->altroot = dget(old->altroot);
565 fs->altrootmnt = NULL;
568 read_unlock(&old->lock);
573 struct fs_struct *copy_fs_struct(struct fs_struct *old)
575 return __copy_fs_struct(old);
578 EXPORT_SYMBOL_GPL(copy_fs_struct);
580 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
582 if (clone_flags & CLONE_FS) {
583 atomic_inc(¤t->fs->count);
586 tsk->fs = __copy_fs_struct(current->fs);
592 static int count_open_files(struct fdtable *fdt)
594 int size = fdt->max_fdset;
597 /* Find the last open fd */
598 for (i = size/(8*sizeof(long)); i > 0; ) {
599 if (fdt->open_fds->fds_bits[--i])
602 i = (i+1) * 8 * sizeof(long);
606 static struct files_struct *alloc_files(void)
608 struct files_struct *newf;
611 newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
615 atomic_set(&newf->count, 1);
617 spin_lock_init(&newf->file_lock);
620 fdt->max_fds = NR_OPEN_DEFAULT;
621 fdt->max_fdset = EMBEDDED_FD_SET_SIZE;
622 fdt->close_on_exec = (fd_set *)&newf->close_on_exec_init;
623 fdt->open_fds = (fd_set *)&newf->open_fds_init;
624 fdt->fd = &newf->fd_array[0];
625 INIT_RCU_HEAD(&fdt->rcu);
626 fdt->free_files = NULL;
628 rcu_assign_pointer(newf->fdt, fdt);
634 * Allocate a new files structure and copy contents from the
635 * passed in files structure.
637 static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
639 struct files_struct *newf;
640 struct file **old_fds, **new_fds;
641 int open_files, size, i, expand;
642 struct fdtable *old_fdt, *new_fdt;
644 newf = alloc_files();
648 spin_lock(&oldf->file_lock);
649 old_fdt = files_fdtable(oldf);
650 new_fdt = files_fdtable(newf);
651 size = old_fdt->max_fdset;
652 open_files = count_open_files(old_fdt);
656 * Check whether we need to allocate a larger fd array or fd set.
657 * Note: we're not a clone task, so the open count won't change.
659 if (open_files > new_fdt->max_fdset) {
660 new_fdt->max_fdset = 0;
663 if (open_files > new_fdt->max_fds) {
664 new_fdt->max_fds = 0;
668 /* if the old fdset gets grown now, we'll only copy up to "size" fds */
670 spin_unlock(&oldf->file_lock);
671 spin_lock(&newf->file_lock);
672 *errorp = expand_files(newf, open_files-1);
673 spin_unlock(&newf->file_lock);
676 new_fdt = files_fdtable(newf);
678 * Reacquire the oldf lock and a pointer to its fd table
679 * who knows it may have a new bigger fd table. We need
680 * the latest pointer.
682 spin_lock(&oldf->file_lock);
683 old_fdt = files_fdtable(oldf);
686 old_fds = old_fdt->fd;
687 new_fds = new_fdt->fd;
689 memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
690 memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
692 for (i = open_files; i != 0; i--) {
693 struct file *f = *old_fds++;
696 /* FIXME: sum it first for check and performance */
697 vx_openfd_inc(open_files - i);
700 * The fd may be claimed in the fd bitmap but not yet
701 * instantiated in the files array if a sibling thread
702 * is partway through open(). So make sure that this
703 * fd is available to the new process.
705 FD_CLR(open_files - i, new_fdt->open_fds);
707 rcu_assign_pointer(*new_fds++, f);
709 spin_unlock(&oldf->file_lock);
711 /* compute the remainder to be cleared */
712 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
714 /* This is long word aligned thus could use a optimized version */
715 memset(new_fds, 0, size);
717 if (new_fdt->max_fdset > open_files) {
718 int left = (new_fdt->max_fdset-open_files)/8;
719 int start = open_files / (8 * sizeof(unsigned long));
721 memset(&new_fdt->open_fds->fds_bits[start], 0, left);
722 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
729 free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
730 free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
731 free_fd_array(new_fdt->fd, new_fdt->max_fds);
732 kmem_cache_free(files_cachep, newf);
736 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
738 struct files_struct *oldf, *newf;
742 * A background process may not have any files ...
744 oldf = current->files;
748 if (clone_flags & CLONE_FILES) {
749 atomic_inc(&oldf->count);
754 * Note: we may be using current for both targets (See exec.c)
755 * This works because we cache current->files (old) as oldf. Don't
760 newf = dup_fd(oldf, &error);
771 * Helper to unshare the files of the current task.
772 * We don't want to expose copy_files internals to
773 * the exec layer of the kernel.
776 int unshare_files(void)
778 struct files_struct *files = current->files;
783 /* This can race but the race causes us to copy when we don't
784 need to and drop the copy */
785 if(atomic_read(&files->count) == 1)
787 atomic_inc(&files->count);
790 rc = copy_files(0, current);
792 current->files = files;
796 EXPORT_SYMBOL(unshare_files);
798 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
800 struct sighand_struct *sig;
802 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
803 atomic_inc(¤t->sighand->count);
806 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
807 rcu_assign_pointer(tsk->sighand, sig);
810 atomic_set(&sig->count, 1);
811 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
815 void __cleanup_sighand(struct sighand_struct *sighand)
817 if (atomic_dec_and_test(&sighand->count))
818 kmem_cache_free(sighand_cachep, sighand);
821 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
823 struct signal_struct *sig;
826 if (clone_flags & CLONE_THREAD) {
827 atomic_inc(¤t->signal->count);
828 atomic_inc(¤t->signal->live);
831 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
836 ret = copy_thread_group_keys(tsk);
838 kmem_cache_free(signal_cachep, sig);
842 atomic_set(&sig->count, 1);
843 atomic_set(&sig->live, 1);
844 init_waitqueue_head(&sig->wait_chldexit);
846 sig->group_exit_code = 0;
847 sig->group_exit_task = NULL;
848 sig->group_stop_count = 0;
849 sig->curr_target = NULL;
850 init_sigpending(&sig->shared_pending);
851 INIT_LIST_HEAD(&sig->posix_timers);
853 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL);
854 sig->it_real_incr.tv64 = 0;
855 sig->real_timer.function = it_real_fn;
858 sig->it_virt_expires = cputime_zero;
859 sig->it_virt_incr = cputime_zero;
860 sig->it_prof_expires = cputime_zero;
861 sig->it_prof_incr = cputime_zero;
863 sig->leader = 0; /* session leadership doesn't inherit */
864 sig->tty_old_pgrp = 0;
866 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
867 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
868 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
870 INIT_LIST_HEAD(&sig->cpu_timers[0]);
871 INIT_LIST_HEAD(&sig->cpu_timers[1]);
872 INIT_LIST_HEAD(&sig->cpu_timers[2]);
874 task_lock(current->group_leader);
875 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
876 task_unlock(current->group_leader);
878 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
880 * New sole thread in the process gets an expiry time
881 * of the whole CPU time limit.
883 tsk->it_prof_expires =
884 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
890 void __cleanup_signal(struct signal_struct *sig)
892 exit_thread_group_keys(sig);
893 kmem_cache_free(signal_cachep, sig);
896 static inline void cleanup_signal(struct task_struct *tsk)
898 struct signal_struct *sig = tsk->signal;
900 atomic_dec(&sig->live);
902 if (atomic_dec_and_test(&sig->count))
903 __cleanup_signal(sig);
906 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
908 unsigned long new_flags = p->flags;
910 new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
911 new_flags |= PF_FORKNOEXEC;
912 if (!(clone_flags & CLONE_PTRACE))
914 p->flags = new_flags;
917 asmlinkage long sys_set_tid_address(int __user *tidptr)
919 current->clear_child_tid = tidptr;
925 * This creates a new process as a copy of the old one,
926 * but does not actually start it yet.
928 * It copies the registers, and all the appropriate
929 * parts of the process environment (as per the clone
930 * flags). The actual kick-off is left to the caller.
932 static task_t *copy_process(unsigned long clone_flags,
933 unsigned long stack_start,
934 struct pt_regs *regs,
935 unsigned long stack_size,
936 int __user *parent_tidptr,
937 int __user *child_tidptr,
941 struct task_struct *p = NULL;
945 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
946 return ERR_PTR(-EINVAL);
949 * Thread groups must share signals as well, and detached threads
950 * can only be started up within the thread group.
952 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
953 return ERR_PTR(-EINVAL);
956 * Shared signal handlers imply shared VM. By way of the above,
957 * thread groups also imply shared VM. Blocking this case allows
958 * for various simplifications in other code.
960 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
961 return ERR_PTR(-EINVAL);
963 retval = security_task_create(clone_flags);
968 p = dup_task_struct(current);
973 init_vx_info(&p->vx_info, current->vx_info);
974 init_nx_info(&p->nx_info, current->nx_info);
976 /* check vserver memory */
977 if (p->mm && !(clone_flags & CLONE_VM)) {
978 if (vx_vmpages_avail(p->mm, p->mm->total_vm))
979 vx_pages_add(p->vx_info, RLIMIT_AS, p->mm->total_vm);
983 if (p->mm && vx_flags(VXF_FORK_RSS, 0)) {
984 if (!vx_rsspages_avail(p->mm, get_mm_counter(p->mm, file_rss)))
985 goto bad_fork_cleanup_vm;
989 if (!vx_nproc_avail(1))
990 goto bad_fork_cleanup_vm;
992 if (atomic_read(&p->user->processes) >=
993 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
994 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
995 p->user != &root_user)
996 goto bad_fork_cleanup_vm;
999 atomic_inc(&p->user->__count);
1000 atomic_inc(&p->user->processes);
1001 get_group_info(p->group_info);
1004 * If multiple threads are within copy_process(), then this check
1005 * triggers too late. This doesn't hurt, the check is only there
1006 * to stop root fork bombs.
1008 if (nr_threads >= max_threads)
1009 goto bad_fork_cleanup_count;
1011 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1012 goto bad_fork_cleanup_count;
1014 if (p->binfmt && !try_module_get(p->binfmt->module))
1015 goto bad_fork_cleanup_put_domain;
1018 copy_flags(clone_flags, p);
1021 if (clone_flags & CLONE_PARENT_SETTID)
1022 if (put_user(p->pid, parent_tidptr))
1023 goto bad_fork_cleanup;
1025 p->proc_dentry = NULL;
1027 INIT_LIST_HEAD(&p->children);
1028 INIT_LIST_HEAD(&p->sibling);
1029 p->vfork_done = NULL;
1030 spin_lock_init(&p->alloc_lock);
1031 spin_lock_init(&p->proc_lock);
1033 clear_tsk_thread_flag(p, TIF_SIGPENDING);
1034 init_sigpending(&p->pending);
1036 p->utime = cputime_zero;
1037 p->stime = cputime_zero;
1039 p->rchar = 0; /* I/O counter: bytes read */
1040 p->wchar = 0; /* I/O counter: bytes written */
1041 p->syscr = 0; /* I/O counter: read syscalls */
1042 p->syscw = 0; /* I/O counter: write syscalls */
1043 acct_clear_integrals(p);
1045 p->it_virt_expires = cputime_zero;
1046 p->it_prof_expires = cputime_zero;
1047 p->it_sched_expires = 0;
1048 INIT_LIST_HEAD(&p->cpu_timers[0]);
1049 INIT_LIST_HEAD(&p->cpu_timers[1]);
1050 INIT_LIST_HEAD(&p->cpu_timers[2]);
1052 p->lock_depth = -1; /* -1 = no lock */
1053 do_posix_clock_monotonic_gettime(&p->start_time);
1055 p->io_context = NULL;
1057 p->audit_context = NULL;
1060 p->mempolicy = mpol_copy(p->mempolicy);
1061 if (IS_ERR(p->mempolicy)) {
1062 retval = PTR_ERR(p->mempolicy);
1063 p->mempolicy = NULL;
1064 goto bad_fork_cleanup_cpuset;
1066 mpol_fix_fork_child_flag(p);
1069 #ifdef CONFIG_DEBUG_MUTEXES
1070 p->blocked_on = NULL; /* not blocked yet */
1074 if (clone_flags & CLONE_THREAD)
1075 p->tgid = current->tgid;
1077 if ((retval = security_task_alloc(p)))
1078 goto bad_fork_cleanup_policy;
1079 if ((retval = audit_alloc(p)))
1080 goto bad_fork_cleanup_security;
1081 /* copy all the process information */
1082 if ((retval = copy_semundo(clone_flags, p)))
1083 goto bad_fork_cleanup_audit;
1084 if ((retval = copy_files(clone_flags, p)))
1085 goto bad_fork_cleanup_semundo;
1086 if ((retval = copy_fs(clone_flags, p)))
1087 goto bad_fork_cleanup_files;
1088 if ((retval = copy_sighand(clone_flags, p)))
1089 goto bad_fork_cleanup_fs;
1090 if ((retval = copy_signal(clone_flags, p)))
1091 goto bad_fork_cleanup_sighand;
1092 if ((retval = copy_mm(clone_flags, p)))
1093 goto bad_fork_cleanup_signal;
1094 if ((retval = copy_keys(clone_flags, p)))
1095 goto bad_fork_cleanup_mm;
1096 if ((retval = copy_namespace(clone_flags, p)))
1097 goto bad_fork_cleanup_keys;
1098 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1100 goto bad_fork_cleanup_namespace;
1102 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1104 * Clear TID on mm_release()?
1106 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1107 p->robust_list = NULL;
1108 #ifdef CONFIG_COMPAT
1109 p->compat_robust_list = NULL;
1112 * sigaltstack should be cleared when sharing the same VM
1114 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1115 p->sas_ss_sp = p->sas_ss_size = 0;
1118 * Syscall tracing should be turned off in the child regardless
1121 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1122 #ifdef TIF_SYSCALL_EMU
1123 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1126 /* Our parent execution domain becomes current domain
1127 These must match for thread signalling to apply */
1129 p->parent_exec_id = p->self_exec_id;
1131 /* ok, now we should be set up.. */
1132 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1133 p->pdeath_signal = 0;
1137 * Ok, make it visible to the rest of the system.
1138 * We dont wake it up yet.
1140 p->group_leader = p;
1141 INIT_LIST_HEAD(&p->thread_group);
1142 INIT_LIST_HEAD(&p->ptrace_children);
1143 INIT_LIST_HEAD(&p->ptrace_list);
1145 /* Perform scheduler related setup. Assign this task to a CPU. */
1146 sched_fork(p, clone_flags);
1148 /* Need tasklist lock for parent etc handling! */
1149 write_lock_irq(&tasklist_lock);
1152 * The task hasn't been attached yet, so its cpus_allowed mask will
1153 * not be changed, nor will its assigned CPU.
1155 * The cpus_allowed mask of the parent may have changed after it was
1156 * copied first time - so re-copy it here, then check the child's CPU
1157 * to ensure it is on a valid CPU (and if not, just force it back to
1158 * parent's CPU). This avoids alot of nasty races.
1160 p->cpus_allowed = current->cpus_allowed;
1161 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1162 !cpu_online(task_cpu(p))))
1163 set_task_cpu(p, smp_processor_id());
1165 /* CLONE_PARENT re-uses the old parent */
1166 if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1167 p->real_parent = current->real_parent;
1169 p->real_parent = current;
1170 p->parent = p->real_parent;
1172 spin_lock(¤t->sighand->siglock);
1175 * Process group and session signals need to be delivered to just the
1176 * parent before the fork or both the parent and the child after the
1177 * fork. Restart if a signal comes in before we add the new process to
1178 * it's process group.
1179 * A fatal signal pending means that current will exit, so the new
1180 * thread can't slip out of an OOM kill (or normal SIGKILL).
1182 recalc_sigpending();
1183 if (signal_pending(current)) {
1184 spin_unlock(¤t->sighand->siglock);
1185 write_unlock_irq(&tasklist_lock);
1186 retval = -ERESTARTNOINTR;
1187 goto bad_fork_cleanup_namespace;
1190 if (clone_flags & CLONE_THREAD) {
1192 * Important: if an exit-all has been started then
1193 * do not create this new thread - the whole thread
1194 * group is supposed to exit anyway.
1196 if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1197 spin_unlock(¤t->sighand->siglock);
1198 write_unlock_irq(&tasklist_lock);
1200 goto bad_fork_cleanup_namespace;
1203 p->group_leader = current->group_leader;
1204 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1206 if (!cputime_eq(current->signal->it_virt_expires,
1208 !cputime_eq(current->signal->it_prof_expires,
1210 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1211 !list_empty(¤t->signal->cpu_timers[0]) ||
1212 !list_empty(¤t->signal->cpu_timers[1]) ||
1213 !list_empty(¤t->signal->cpu_timers[2])) {
1215 * Have child wake up on its first tick to check
1216 * for process CPU timers.
1218 p->it_prof_expires = jiffies_to_cputime(1);
1225 p->ioprio = current->ioprio;
1227 if (likely(p->pid)) {
1229 if (unlikely(p->ptrace & PT_PTRACED))
1230 __ptrace_link(p, current->parent);
1232 if (thread_group_leader(p)) {
1233 p->signal->tty = current->signal->tty;
1234 p->signal->pgrp = process_group(current);
1235 p->signal->session = current->signal->session;
1236 attach_pid(p, PIDTYPE_PGID, process_group(p));
1237 attach_pid(p, PIDTYPE_SID, p->signal->session);
1239 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1240 __get_cpu_var(process_counts)++;
1242 attach_pid(p, PIDTYPE_PID, p->pid);
1247 spin_unlock(¤t->sighand->siglock);
1249 /* p is copy of current */
1252 claim_vx_info(vxi, p);
1253 atomic_inc(&vxi->cvirt.nr_threads);
1254 atomic_inc(&vxi->cvirt.total_forks);
1259 claim_nx_info(nxi, p);
1260 write_unlock_irq(&tasklist_lock);
1261 proc_fork_connector(p);
1264 bad_fork_cleanup_namespace:
1266 bad_fork_cleanup_keys:
1268 bad_fork_cleanup_mm:
1271 bad_fork_cleanup_signal:
1273 bad_fork_cleanup_sighand:
1274 __cleanup_sighand(p->sighand);
1275 bad_fork_cleanup_fs:
1276 exit_fs(p); /* blocking */
1277 bad_fork_cleanup_files:
1278 exit_files(p); /* blocking */
1279 bad_fork_cleanup_semundo:
1281 bad_fork_cleanup_audit:
1283 bad_fork_cleanup_security:
1284 security_task_free(p);
1285 bad_fork_cleanup_policy:
1287 mpol_free(p->mempolicy);
1288 bad_fork_cleanup_cpuset:
1293 module_put(p->binfmt->module);
1294 bad_fork_cleanup_put_domain:
1295 module_put(task_thread_info(p)->exec_domain->module);
1296 bad_fork_cleanup_count:
1297 put_group_info(p->group_info);
1298 atomic_dec(&p->user->processes);
1300 bad_fork_cleanup_vm:
1301 if (p->mm && !(clone_flags & CLONE_VM))
1302 vx_pages_sub(p->vx_info, RLIMIT_AS, p->mm->total_vm);
1306 return ERR_PTR(retval);
1309 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1311 memset(regs, 0, sizeof(struct pt_regs));
1315 task_t * __devinit fork_idle(int cpu)
1318 struct pt_regs regs;
1320 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0);
1322 return ERR_PTR(-ENOMEM);
1323 init_idle(task, cpu);
1328 static inline int fork_traceflag (unsigned clone_flags)
1330 if (clone_flags & CLONE_UNTRACED)
1332 else if (clone_flags & CLONE_VFORK) {
1333 if (current->ptrace & PT_TRACE_VFORK)
1334 return PTRACE_EVENT_VFORK;
1335 } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1336 if (current->ptrace & PT_TRACE_CLONE)
1337 return PTRACE_EVENT_CLONE;
1338 } else if (current->ptrace & PT_TRACE_FORK)
1339 return PTRACE_EVENT_FORK;
1345 * Ok, this is the main fork-routine.
1347 * It copies the process, and if successful kick-starts
1348 * it and waits for it to finish using the VM if required.
1350 long do_fork(unsigned long clone_flags,
1351 unsigned long stack_start,
1352 struct pt_regs *regs,
1353 unsigned long stack_size,
1354 int __user *parent_tidptr,
1355 int __user *child_tidptr)
1357 struct task_struct *p;
1359 struct pid *pid = alloc_pid();
1366 if (unlikely(current->ptrace)) {
1367 trace = fork_traceflag (clone_flags);
1369 clone_flags |= CLONE_PTRACE;
1372 p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, nr);
1374 * Do this prior waking up the new thread - the thread pointer
1375 * might get invalid after that point, if the thread exits quickly.
1378 struct completion vfork;
1380 if (clone_flags & CLONE_VFORK) {
1381 p->vfork_done = &vfork;
1382 init_completion(&vfork);
1385 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1387 * We'll start up with an immediate SIGSTOP.
1389 sigaddset(&p->pending.signal, SIGSTOP);
1390 set_tsk_thread_flag(p, TIF_SIGPENDING);
1393 if (!(clone_flags & CLONE_STOPPED))
1394 wake_up_new_task(p, clone_flags);
1396 p->state = TASK_STOPPED;
1398 if (unlikely (trace)) {
1399 current->ptrace_message = nr;
1400 ptrace_notify ((trace << 8) | SIGTRAP);
1403 if (clone_flags & CLONE_VFORK) {
1404 wait_for_completion(&vfork);
1405 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1406 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1415 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1416 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1419 static void sighand_ctor(void *data, kmem_cache_t *cachep, unsigned long flags)
1421 struct sighand_struct *sighand = data;
1423 if ((flags & (SLAB_CTOR_VERIFY | SLAB_CTOR_CONSTRUCTOR)) ==
1424 SLAB_CTOR_CONSTRUCTOR)
1425 spin_lock_init(&sighand->siglock);
1428 void __init proc_caches_init(void)
1430 sighand_cachep = kmem_cache_create("sighand_cache",
1431 sizeof(struct sighand_struct), 0,
1432 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU,
1433 sighand_ctor, NULL);
1434 signal_cachep = kmem_cache_create("signal_cache",
1435 sizeof(struct signal_struct), 0,
1436 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1437 files_cachep = kmem_cache_create("files_cache",
1438 sizeof(struct files_struct), 0,
1439 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1440 fs_cachep = kmem_cache_create("fs_cache",
1441 sizeof(struct fs_struct), 0,
1442 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1443 vm_area_cachep = kmem_cache_create("vm_area_struct",
1444 sizeof(struct vm_area_struct), 0,
1445 SLAB_PANIC, NULL, NULL);
1446 mm_cachep = kmem_cache_create("mm_struct",
1447 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1448 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1453 * Check constraints on flags passed to the unshare system call and
1454 * force unsharing of additional process context as appropriate.
1456 static inline void check_unshare_flags(unsigned long *flags_ptr)
1459 * If unsharing a thread from a thread group, must also
1462 if (*flags_ptr & CLONE_THREAD)
1463 *flags_ptr |= CLONE_VM;
1466 * If unsharing vm, must also unshare signal handlers.
1468 if (*flags_ptr & CLONE_VM)
1469 *flags_ptr |= CLONE_SIGHAND;
1472 * If unsharing signal handlers and the task was created
1473 * using CLONE_THREAD, then must unshare the thread
1475 if ((*flags_ptr & CLONE_SIGHAND) &&
1476 (atomic_read(¤t->signal->count) > 1))
1477 *flags_ptr |= CLONE_THREAD;
1480 * If unsharing namespace, must also unshare filesystem information.
1482 if (*flags_ptr & CLONE_NEWNS)
1483 *flags_ptr |= CLONE_FS;
1487 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1489 static int unshare_thread(unsigned long unshare_flags)
1491 if (unshare_flags & CLONE_THREAD)
1498 * Unshare the filesystem structure if it is being shared
1500 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1502 struct fs_struct *fs = current->fs;
1504 if ((unshare_flags & CLONE_FS) &&
1505 (fs && atomic_read(&fs->count) > 1)) {
1506 *new_fsp = __copy_fs_struct(current->fs);
1515 * Unshare the namespace structure if it is being shared
1517 static int unshare_namespace(unsigned long unshare_flags, struct namespace **new_nsp, struct fs_struct *new_fs)
1519 struct namespace *ns = current->namespace;
1521 if ((unshare_flags & CLONE_NEWNS) &&
1522 (ns && atomic_read(&ns->count) > 1)) {
1523 if (!capable(CAP_SYS_ADMIN))
1526 *new_nsp = dup_namespace(current, new_fs ? new_fs : current->fs);
1535 * Unsharing of sighand for tasks created with CLONE_SIGHAND is not
1538 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
1540 struct sighand_struct *sigh = current->sighand;
1542 if ((unshare_flags & CLONE_SIGHAND) &&
1543 (sigh && atomic_read(&sigh->count) > 1))
1550 * Unshare vm if it is being shared
1552 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
1554 struct mm_struct *mm = current->mm;
1556 if ((unshare_flags & CLONE_VM) &&
1557 (mm && atomic_read(&mm->mm_users) > 1)) {
1565 * Unshare file descriptor table if it is being shared
1567 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1569 struct files_struct *fd = current->files;
1572 if ((unshare_flags & CLONE_FILES) &&
1573 (fd && atomic_read(&fd->count) > 1)) {
1574 *new_fdp = dup_fd(fd, &error);
1583 * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not
1586 static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp)
1588 if (unshare_flags & CLONE_SYSVSEM)
1595 * unshare allows a process to 'unshare' part of the process
1596 * context which was originally shared using clone. copy_*
1597 * functions used by do_fork() cannot be used here directly
1598 * because they modify an inactive task_struct that is being
1599 * constructed. Here we are modifying the current, active,
1602 asmlinkage long sys_unshare(unsigned long unshare_flags)
1605 struct fs_struct *fs, *new_fs = NULL;
1606 struct namespace *ns, *new_ns = NULL;
1607 struct sighand_struct *sigh, *new_sigh = NULL;
1608 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
1609 struct files_struct *fd, *new_fd = NULL;
1610 struct sem_undo_list *new_ulist = NULL;
1612 check_unshare_flags(&unshare_flags);
1614 /* Return -EINVAL for all unsupported flags */
1616 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1617 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM))
1618 goto bad_unshare_out;
1620 if ((err = unshare_thread(unshare_flags)))
1621 goto bad_unshare_out;
1622 if ((err = unshare_fs(unshare_flags, &new_fs)))
1623 goto bad_unshare_cleanup_thread;
1624 if ((err = unshare_namespace(unshare_flags, &new_ns, new_fs)))
1625 goto bad_unshare_cleanup_fs;
1626 if ((err = unshare_sighand(unshare_flags, &new_sigh)))
1627 goto bad_unshare_cleanup_ns;
1628 if ((err = unshare_vm(unshare_flags, &new_mm)))
1629 goto bad_unshare_cleanup_sigh;
1630 if ((err = unshare_fd(unshare_flags, &new_fd)))
1631 goto bad_unshare_cleanup_vm;
1632 if ((err = unshare_semundo(unshare_flags, &new_ulist)))
1633 goto bad_unshare_cleanup_fd;
1635 if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist) {
1641 current->fs = new_fs;
1646 ns = current->namespace;
1647 current->namespace = new_ns;
1652 sigh = current->sighand;
1653 rcu_assign_pointer(current->sighand, new_sigh);
1659 active_mm = current->active_mm;
1660 current->mm = new_mm;
1661 current->active_mm = new_mm;
1662 activate_mm(active_mm, new_mm);
1667 fd = current->files;
1668 current->files = new_fd;
1672 task_unlock(current);
1675 bad_unshare_cleanup_fd:
1677 put_files_struct(new_fd);
1679 bad_unshare_cleanup_vm:
1683 bad_unshare_cleanup_sigh:
1685 if (atomic_dec_and_test(&new_sigh->count))
1686 kmem_cache_free(sighand_cachep, new_sigh);
1688 bad_unshare_cleanup_ns:
1690 put_namespace(new_ns);
1692 bad_unshare_cleanup_fs:
1694 put_fs_struct(new_fs);
1696 bad_unshare_cleanup_thread: