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 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_cb(struct rcu_head *rhp)
119 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
121 WARN_ON(!(tsk->exit_state & (EXIT_DEAD | EXIT_ZOMBIE)));
122 WARN_ON(atomic_read(&tsk->usage));
123 WARN_ON(tsk == current);
125 if (unlikely(tsk->audit_context))
127 security_task_free(tsk);
129 put_group_info(tsk->group_info);
131 if (!profile_handoff_task(tsk))
135 void __init fork_init(unsigned long mempages)
137 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
138 #ifndef ARCH_MIN_TASKALIGN
139 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
141 /* create a slab on which task_structs can be allocated */
143 kmem_cache_create("task_struct", sizeof(struct task_struct),
144 ARCH_MIN_TASKALIGN, SLAB_PANIC, NULL, NULL);
148 * The default maximum number of threads is set to a safe
149 * value: the thread structures can take up at most half
152 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
155 * we need to allow at least 20 threads to boot a system
160 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
161 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
162 init_task.signal->rlim[RLIMIT_SIGPENDING] =
163 init_task.signal->rlim[RLIMIT_NPROC];
166 static struct task_struct *dup_task_struct(struct task_struct *orig)
168 struct task_struct *tsk;
169 struct thread_info *ti;
171 prepare_to_copy(orig);
173 tsk = alloc_task_struct();
177 ti = alloc_thread_info(tsk);
179 free_task_struct(tsk);
184 tsk->thread_info = ti;
185 setup_thread_stack(tsk, orig);
187 /* One for us, one for whoever does the "release_task()" (usually parent) */
188 atomic_set(&tsk->usage,2);
189 atomic_set(&tsk->fs_excl, 0);
194 static inline int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
196 struct vm_area_struct *mpnt, *tmp, **pprev;
197 struct rb_node **rb_link, *rb_parent;
199 unsigned long charge;
200 struct mempolicy *pol;
202 down_write(&oldmm->mmap_sem);
203 flush_cache_mm(oldmm);
204 down_write(&mm->mmap_sem);
208 mm->mmap_cache = NULL;
209 mm->free_area_cache = oldmm->mmap_base;
210 mm->cached_hole_size = ~0UL;
212 __set_mm_counter(mm, file_rss, 0);
213 __set_mm_counter(mm, anon_rss, 0);
214 cpus_clear(mm->cpu_vm_mask);
216 rb_link = &mm->mm_rb.rb_node;
220 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
223 if (mpnt->vm_flags & VM_DONTCOPY) {
224 long pages = vma_pages(mpnt);
225 vx_vmpages_sub(mm, pages);
226 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
231 if (mpnt->vm_flags & VM_ACCOUNT) {
232 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
233 if (security_vm_enough_memory(len))
237 tmp = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL);
241 pol = mpol_copy(vma_policy(mpnt));
242 retval = PTR_ERR(pol);
244 goto fail_nomem_policy;
245 vma_set_policy(tmp, pol);
246 tmp->vm_flags &= ~VM_LOCKED;
252 struct inode *inode = file->f_dentry->d_inode;
254 if (tmp->vm_flags & VM_DENYWRITE)
255 atomic_dec(&inode->i_writecount);
257 /* insert tmp into the share list, just after mpnt */
258 spin_lock(&file->f_mapping->i_mmap_lock);
259 tmp->vm_truncate_count = mpnt->vm_truncate_count;
260 flush_dcache_mmap_lock(file->f_mapping);
261 vma_prio_tree_add(tmp, mpnt);
262 flush_dcache_mmap_unlock(file->f_mapping);
263 spin_unlock(&file->f_mapping->i_mmap_lock);
267 * Link in the new vma and copy the page table entries.
270 pprev = &tmp->vm_next;
272 __vma_link_rb(mm, tmp, rb_link, rb_parent);
273 rb_link = &tmp->vm_rb.rb_right;
274 rb_parent = &tmp->vm_rb;
277 retval = copy_page_range(mm, oldmm, mpnt);
279 if (tmp->vm_ops && tmp->vm_ops->open)
280 tmp->vm_ops->open(tmp);
287 up_write(&mm->mmap_sem);
289 up_write(&oldmm->mmap_sem);
292 kmem_cache_free(vm_area_cachep, tmp);
295 vm_unacct_memory(charge);
299 static inline int mm_alloc_pgd(struct mm_struct * mm)
301 mm->pgd = pgd_alloc(mm);
302 if (unlikely(!mm->pgd))
307 static inline void mm_free_pgd(struct mm_struct * mm)
312 #define dup_mmap(mm, oldmm) (0)
313 #define mm_alloc_pgd(mm) (0)
314 #define mm_free_pgd(mm)
315 #endif /* CONFIG_MMU */
317 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
319 #define allocate_mm() (kmem_cache_alloc(mm_cachep, SLAB_KERNEL))
320 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
322 #include <linux/init_task.h>
324 static struct mm_struct * mm_init(struct mm_struct * mm)
326 atomic_set(&mm->mm_users, 1);
327 atomic_set(&mm->mm_count, 1);
328 init_rwsem(&mm->mmap_sem);
329 INIT_LIST_HEAD(&mm->mmlist);
330 mm->core_waiters = 0;
332 spin_lock_init(&mm->page_table_lock);
333 rwlock_init(&mm->ioctx_list_lock);
334 mm->ioctx_list = NULL;
335 mm->free_area_cache = TASK_UNMAPPED_BASE;
336 mm->cached_hole_size = ~0UL;
338 if (likely(!mm_alloc_pgd(mm))) {
340 set_vx_info(&mm->mm_vx_info, current->vx_info);
348 * Allocate and initialize an mm_struct.
350 struct mm_struct * mm_alloc(void)
352 struct mm_struct * mm;
356 memset(mm, 0, sizeof(*mm));
363 * Called when the last reference to the mm
364 * is dropped: either by a lazy thread or by
365 * mmput. Free the page directory and the mm.
367 void fastcall __mmdrop(struct mm_struct *mm)
369 BUG_ON(mm == &init_mm);
372 clr_vx_info(&mm->mm_vx_info);
377 * Decrement the use count and release all resources for an mm.
379 void mmput(struct mm_struct *mm)
381 if (atomic_dec_and_test(&mm->mm_users)) {
384 if (!list_empty(&mm->mmlist)) {
385 spin_lock(&mmlist_lock);
386 list_del(&mm->mmlist);
387 spin_unlock(&mmlist_lock);
393 EXPORT_SYMBOL_GPL(mmput);
396 * get_task_mm - acquire a reference to the task's mm
398 * Returns %NULL if the task has no mm. Checks PF_BORROWED_MM (meaning
399 * this kernel workthread has transiently adopted a user mm with use_mm,
400 * to do its AIO) is not set and if so returns a reference to it, after
401 * bumping up the use count. User must release the mm via mmput()
402 * after use. Typically used by /proc and ptrace.
404 struct mm_struct *get_task_mm(struct task_struct *task)
406 struct mm_struct *mm;
411 if (task->flags & PF_BORROWED_MM)
414 atomic_inc(&mm->mm_users);
419 EXPORT_SYMBOL_GPL(get_task_mm);
421 /* Please note the differences between mmput and mm_release.
422 * mmput is called whenever we stop holding onto a mm_struct,
423 * error success whatever.
425 * mm_release is called after a mm_struct has been removed
426 * from the current process.
428 * This difference is important for error handling, when we
429 * only half set up a mm_struct for a new process and need to restore
430 * the old one. Because we mmput the new mm_struct before
431 * restoring the old one. . .
432 * Eric Biederman 10 January 1998
434 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
436 struct completion *vfork_done = tsk->vfork_done;
438 /* Get rid of any cached register state */
439 deactivate_mm(tsk, mm);
441 /* notify parent sleeping on vfork() */
443 tsk->vfork_done = NULL;
444 complete(vfork_done);
446 if (tsk->clear_child_tid && atomic_read(&mm->mm_users) > 1) {
447 u32 __user * tidptr = tsk->clear_child_tid;
448 tsk->clear_child_tid = NULL;
451 * We don't check the error code - if userspace has
452 * not set up a proper pointer then tough luck.
455 sys_futex(tidptr, FUTEX_WAKE, 1, NULL, NULL, 0);
460 * Allocate a new mm structure and copy contents from the
461 * mm structure of the passed in task structure.
463 static struct mm_struct *dup_mm(struct task_struct *tsk)
465 struct mm_struct *mm, *oldmm = current->mm;
475 memcpy(mm, oldmm, sizeof(*mm));
476 mm->mm_vx_info = NULL;
481 if (init_new_context(tsk, mm))
484 err = dup_mmap(mm, oldmm);
488 mm->hiwater_rss = get_mm_rss(mm);
489 mm->hiwater_vm = mm->total_vm;
501 * If init_new_context() failed, we cannot use mmput() to free the mm
502 * because it calls destroy_context()
504 clr_vx_info(&mm->mm_vx_info);
510 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
512 struct mm_struct * mm, *oldmm;
515 tsk->min_flt = tsk->maj_flt = 0;
516 tsk->nvcsw = tsk->nivcsw = 0;
519 tsk->active_mm = NULL;
522 * Are we cloning a kernel thread?
524 * We need to steal a active VM for that..
530 if (clone_flags & CLONE_VM) {
531 atomic_inc(&oldmm->mm_users);
550 static inline struct fs_struct *__copy_fs_struct(struct fs_struct *old)
552 struct fs_struct *fs = kmem_cache_alloc(fs_cachep, GFP_KERNEL);
553 /* We don't need to lock fs - think why ;-) */
555 atomic_set(&fs->count, 1);
556 rwlock_init(&fs->lock);
557 fs->umask = old->umask;
558 read_lock(&old->lock);
559 fs->rootmnt = mntget(old->rootmnt);
560 fs->root = dget(old->root);
561 fs->pwdmnt = mntget(old->pwdmnt);
562 fs->pwd = dget(old->pwd);
564 fs->altrootmnt = mntget(old->altrootmnt);
565 fs->altroot = dget(old->altroot);
567 fs->altrootmnt = NULL;
570 read_unlock(&old->lock);
575 struct fs_struct *copy_fs_struct(struct fs_struct *old)
577 return __copy_fs_struct(old);
580 EXPORT_SYMBOL_GPL(copy_fs_struct);
582 static inline int copy_fs(unsigned long clone_flags, struct task_struct * tsk)
584 if (clone_flags & CLONE_FS) {
585 atomic_inc(¤t->fs->count);
588 tsk->fs = __copy_fs_struct(current->fs);
594 static int count_open_files(struct fdtable *fdt)
596 int size = fdt->max_fdset;
599 /* Find the last open fd */
600 for (i = size/(8*sizeof(long)); i > 0; ) {
601 if (fdt->open_fds->fds_bits[--i])
604 i = (i+1) * 8 * sizeof(long);
608 static struct files_struct *alloc_files(void)
610 struct files_struct *newf;
613 newf = kmem_cache_alloc(files_cachep, SLAB_KERNEL);
617 atomic_set(&newf->count, 1);
619 spin_lock_init(&newf->file_lock);
622 fdt->max_fds = NR_OPEN_DEFAULT;
623 fdt->max_fdset = __FD_SETSIZE;
624 fdt->close_on_exec = &newf->close_on_exec_init;
625 fdt->open_fds = &newf->open_fds_init;
626 fdt->fd = &newf->fd_array[0];
627 INIT_RCU_HEAD(&fdt->rcu);
628 fdt->free_files = NULL;
630 rcu_assign_pointer(newf->fdt, fdt);
636 * Allocate a new files structure and copy contents from the
637 * passed in files structure.
639 static struct files_struct *dup_fd(struct files_struct *oldf, int *errorp)
641 struct files_struct *newf;
642 struct file **old_fds, **new_fds;
643 int open_files, size, i, expand;
644 struct fdtable *old_fdt, *new_fdt;
646 newf = alloc_files();
650 spin_lock(&oldf->file_lock);
651 old_fdt = files_fdtable(oldf);
652 new_fdt = files_fdtable(newf);
653 size = old_fdt->max_fdset;
654 open_files = count_open_files(old_fdt);
658 * Check whether we need to allocate a larger fd array or fd set.
659 * Note: we're not a clone task, so the open count won't change.
661 if (open_files > new_fdt->max_fdset) {
662 new_fdt->max_fdset = 0;
665 if (open_files > new_fdt->max_fds) {
666 new_fdt->max_fds = 0;
670 /* if the old fdset gets grown now, we'll only copy up to "size" fds */
672 spin_unlock(&oldf->file_lock);
673 spin_lock(&newf->file_lock);
674 *errorp = expand_files(newf, open_files-1);
675 spin_unlock(&newf->file_lock);
678 new_fdt = files_fdtable(newf);
680 * Reacquire the oldf lock and a pointer to its fd table
681 * who knows it may have a new bigger fd table. We need
682 * the latest pointer.
684 spin_lock(&oldf->file_lock);
685 old_fdt = files_fdtable(oldf);
688 old_fds = old_fdt->fd;
689 new_fds = new_fdt->fd;
691 memcpy(new_fdt->open_fds->fds_bits, old_fdt->open_fds->fds_bits, open_files/8);
692 memcpy(new_fdt->close_on_exec->fds_bits, old_fdt->close_on_exec->fds_bits, open_files/8);
694 for (i = open_files; i != 0; i--) {
695 struct file *f = *old_fds++;
698 /* FIXME: sum it first for check and performance */
699 vx_openfd_inc(open_files - i);
702 * The fd may be claimed in the fd bitmap but not yet
703 * instantiated in the files array if a sibling thread
704 * is partway through open(). So make sure that this
705 * fd is available to the new process.
707 FD_CLR(open_files - i, new_fdt->open_fds);
709 rcu_assign_pointer(*new_fds++, f);
711 spin_unlock(&oldf->file_lock);
713 /* compute the remainder to be cleared */
714 size = (new_fdt->max_fds - open_files) * sizeof(struct file *);
716 /* This is long word aligned thus could use a optimized version */
717 memset(new_fds, 0, size);
719 if (new_fdt->max_fdset > open_files) {
720 int left = (new_fdt->max_fdset-open_files)/8;
721 int start = open_files / (8 * sizeof(unsigned long));
723 memset(&new_fdt->open_fds->fds_bits[start], 0, left);
724 memset(&new_fdt->close_on_exec->fds_bits[start], 0, left);
731 free_fdset (new_fdt->close_on_exec, new_fdt->max_fdset);
732 free_fdset (new_fdt->open_fds, new_fdt->max_fdset);
733 free_fd_array(new_fdt->fd, new_fdt->max_fds);
734 kmem_cache_free(files_cachep, newf);
738 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
740 struct files_struct *oldf, *newf;
744 * A background process may not have any files ...
746 oldf = current->files;
750 if (clone_flags & CLONE_FILES) {
751 atomic_inc(&oldf->count);
756 * Note: we may be using current for both targets (See exec.c)
757 * This works because we cache current->files (old) as oldf. Don't
762 newf = dup_fd(oldf, &error);
773 * Helper to unshare the files of the current task.
774 * We don't want to expose copy_files internals to
775 * the exec layer of the kernel.
778 int unshare_files(void)
780 struct files_struct *files = current->files;
786 /* This can race but the race causes us to copy when we don't
787 need to and drop the copy */
788 if(atomic_read(&files->count) == 1)
790 atomic_inc(&files->count);
793 rc = copy_files(0, current);
795 current->files = files;
799 EXPORT_SYMBOL(unshare_files);
801 void sighand_free_cb(struct rcu_head *rhp)
803 struct sighand_struct *sp;
805 sp = container_of(rhp, struct sighand_struct, rcu);
806 kmem_cache_free(sighand_cachep, sp);
809 static inline int copy_sighand(unsigned long clone_flags, struct task_struct * tsk)
811 struct sighand_struct *sig;
813 if (clone_flags & (CLONE_SIGHAND | CLONE_THREAD)) {
814 atomic_inc(¤t->sighand->count);
817 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
818 rcu_assign_pointer(tsk->sighand, sig);
821 spin_lock_init(&sig->siglock);
822 atomic_set(&sig->count, 1);
823 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
827 static inline int copy_signal(unsigned long clone_flags, struct task_struct * tsk)
829 struct signal_struct *sig;
832 if (clone_flags & CLONE_THREAD) {
833 atomic_inc(¤t->signal->count);
834 atomic_inc(¤t->signal->live);
837 sig = kmem_cache_alloc(signal_cachep, GFP_KERNEL);
842 ret = copy_thread_group_keys(tsk);
844 kmem_cache_free(signal_cachep, sig);
848 atomic_set(&sig->count, 1);
849 atomic_set(&sig->live, 1);
850 init_waitqueue_head(&sig->wait_chldexit);
852 sig->group_exit_code = 0;
853 sig->group_exit_task = NULL;
854 sig->group_stop_count = 0;
855 sig->curr_target = NULL;
856 init_sigpending(&sig->shared_pending);
857 INIT_LIST_HEAD(&sig->posix_timers);
859 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL);
860 sig->it_real_incr.tv64 = 0;
861 sig->real_timer.function = it_real_fn;
862 sig->real_timer.data = tsk;
864 sig->it_virt_expires = cputime_zero;
865 sig->it_virt_incr = cputime_zero;
866 sig->it_prof_expires = cputime_zero;
867 sig->it_prof_incr = cputime_zero;
869 sig->leader = 0; /* session leadership doesn't inherit */
870 sig->tty_old_pgrp = 0;
872 sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
873 sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
874 sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
876 INIT_LIST_HEAD(&sig->cpu_timers[0]);
877 INIT_LIST_HEAD(&sig->cpu_timers[1]);
878 INIT_LIST_HEAD(&sig->cpu_timers[2]);
880 task_lock(current->group_leader);
881 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
882 task_unlock(current->group_leader);
884 if (sig->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY) {
886 * New sole thread in the process gets an expiry time
887 * of the whole CPU time limit.
889 tsk->it_prof_expires =
890 secs_to_cputime(sig->rlim[RLIMIT_CPU].rlim_cur);
896 static inline void copy_flags(unsigned long clone_flags, struct task_struct *p)
898 unsigned long new_flags = p->flags;
900 new_flags &= ~(PF_SUPERPRIV | PF_NOFREEZE);
901 new_flags |= PF_FORKNOEXEC;
902 if (!(clone_flags & CLONE_PTRACE))
904 p->flags = new_flags;
907 asmlinkage long sys_set_tid_address(int __user *tidptr)
909 current->clear_child_tid = tidptr;
915 * This creates a new process as a copy of the old one,
916 * but does not actually start it yet.
918 * It copies the registers, and all the appropriate
919 * parts of the process environment (as per the clone
920 * flags). The actual kick-off is left to the caller.
922 static task_t *copy_process(unsigned long clone_flags,
923 unsigned long stack_start,
924 struct pt_regs *regs,
925 unsigned long stack_size,
926 int __user *parent_tidptr,
927 int __user *child_tidptr,
931 struct task_struct *p = NULL;
935 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
936 return ERR_PTR(-EINVAL);
939 * Thread groups must share signals as well, and detached threads
940 * can only be started up within the thread group.
942 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
943 return ERR_PTR(-EINVAL);
946 * Shared signal handlers imply shared VM. By way of the above,
947 * thread groups also imply shared VM. Blocking this case allows
948 * for various simplifications in other code.
950 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
951 return ERR_PTR(-EINVAL);
953 retval = security_task_create(clone_flags);
958 p = dup_task_struct(current);
962 init_vx_info(&p->vx_info, current->vx_info);
963 init_nx_info(&p->nx_info, current->nx_info);
965 /* check vserver memory */
966 if (p->mm && !(clone_flags & CLONE_VM)) {
967 if (vx_vmpages_avail(p->mm, p->mm->total_vm))
968 vx_pages_add(p->vx_info, RLIMIT_AS, p->mm->total_vm);
972 if (p->mm && vx_flags(VXF_FORK_RSS, 0)) {
973 if (!vx_rsspages_avail(p->mm, get_mm_counter(p->mm, file_rss)))
974 goto bad_fork_cleanup_vm;
978 if (!vx_nproc_avail(1))
979 goto bad_fork_cleanup_vm;
981 if (atomic_read(&p->user->processes) >=
982 p->signal->rlim[RLIMIT_NPROC].rlim_cur) {
983 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
984 p->user != &root_user)
985 goto bad_fork_cleanup_vm;
988 atomic_inc(&p->user->__count);
989 atomic_inc(&p->user->processes);
990 get_group_info(p->group_info);
993 * If multiple threads are within copy_process(), then this check
994 * triggers too late. This doesn't hurt, the check is only there
995 * to stop root fork bombs.
997 if (nr_threads >= max_threads)
998 goto bad_fork_cleanup_count;
1000 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1001 goto bad_fork_cleanup_count;
1003 if (p->binfmt && !try_module_get(p->binfmt->module))
1004 goto bad_fork_cleanup_put_domain;
1007 copy_flags(clone_flags, p);
1010 if (clone_flags & CLONE_PARENT_SETTID)
1011 if (put_user(p->pid, parent_tidptr))
1012 goto bad_fork_cleanup;
1014 p->proc_dentry = NULL;
1016 INIT_LIST_HEAD(&p->children);
1017 INIT_LIST_HEAD(&p->sibling);
1018 p->vfork_done = NULL;
1019 spin_lock_init(&p->alloc_lock);
1020 spin_lock_init(&p->proc_lock);
1022 clear_tsk_thread_flag(p, TIF_SIGPENDING);
1023 init_sigpending(&p->pending);
1025 p->utime = cputime_zero;
1026 p->stime = cputime_zero;
1028 p->rchar = 0; /* I/O counter: bytes read */
1029 p->wchar = 0; /* I/O counter: bytes written */
1030 p->syscr = 0; /* I/O counter: read syscalls */
1031 p->syscw = 0; /* I/O counter: write syscalls */
1032 acct_clear_integrals(p);
1034 p->it_virt_expires = cputime_zero;
1035 p->it_prof_expires = cputime_zero;
1036 p->it_sched_expires = 0;
1037 INIT_LIST_HEAD(&p->cpu_timers[0]);
1038 INIT_LIST_HEAD(&p->cpu_timers[1]);
1039 INIT_LIST_HEAD(&p->cpu_timers[2]);
1041 p->lock_depth = -1; /* -1 = no lock */
1042 do_posix_clock_monotonic_gettime(&p->start_time);
1044 p->io_context = NULL;
1046 p->audit_context = NULL;
1049 p->mempolicy = mpol_copy(p->mempolicy);
1050 if (IS_ERR(p->mempolicy)) {
1051 retval = PTR_ERR(p->mempolicy);
1052 p->mempolicy = NULL;
1053 goto bad_fork_cleanup_cpuset;
1057 #ifdef CONFIG_DEBUG_MUTEXES
1058 p->blocked_on = NULL; /* not blocked yet */
1062 if (clone_flags & CLONE_THREAD)
1063 p->tgid = current->tgid;
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_namespace(clone_flags, p)))
1085 goto bad_fork_cleanup_keys;
1086 retval = copy_thread(0, clone_flags, stack_start, stack_size, p, regs);
1088 goto bad_fork_cleanup_namespace;
1090 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1092 * Clear TID on mm_release()?
1094 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1097 * sigaltstack should be cleared when sharing the same VM
1099 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1100 p->sas_ss_sp = p->sas_ss_size = 0;
1103 * Syscall tracing should be turned off in the child regardless
1106 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1107 #ifdef TIF_SYSCALL_EMU
1108 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1111 /* Our parent execution domain becomes current domain
1112 These must match for thread signalling to apply */
1114 p->parent_exec_id = p->self_exec_id;
1116 /* ok, now we should be set up.. */
1117 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1118 p->pdeath_signal = 0;
1122 * Ok, make it visible to the rest of the system.
1123 * We dont wake it up yet.
1125 p->group_leader = p;
1126 INIT_LIST_HEAD(&p->ptrace_children);
1127 INIT_LIST_HEAD(&p->ptrace_list);
1129 /* Perform scheduler related setup. Assign this task to a CPU. */
1130 sched_fork(p, clone_flags);
1132 /* Need tasklist lock for parent etc handling! */
1133 write_lock_irq(&tasklist_lock);
1136 * The task hasn't been attached yet, so its cpus_allowed mask will
1137 * not be changed, nor will its assigned CPU.
1139 * The cpus_allowed mask of the parent may have changed after it was
1140 * copied first time - so re-copy it here, then check the child's CPU
1141 * to ensure it is on a valid CPU (and if not, just force it back to
1142 * parent's CPU). This avoids alot of nasty races.
1144 p->cpus_allowed = current->cpus_allowed;
1145 if (unlikely(!cpu_isset(task_cpu(p), p->cpus_allowed) ||
1146 !cpu_online(task_cpu(p))))
1147 set_task_cpu(p, smp_processor_id());
1150 * Check for pending SIGKILL! The new thread should not be allowed
1151 * to slip out of an OOM kill. (or normal SIGKILL.)
1153 if (sigismember(¤t->pending.signal, SIGKILL)) {
1154 write_unlock_irq(&tasklist_lock);
1156 goto bad_fork_cleanup_namespace;
1159 /* CLONE_PARENT re-uses the old parent */
1160 if (clone_flags & (CLONE_PARENT|CLONE_THREAD))
1161 p->real_parent = current->real_parent;
1163 p->real_parent = current;
1164 p->parent = p->real_parent;
1166 spin_lock(¤t->sighand->siglock);
1167 if (clone_flags & CLONE_THREAD) {
1169 * Important: if an exit-all has been started then
1170 * do not create this new thread - the whole thread
1171 * group is supposed to exit anyway.
1173 if (current->signal->flags & SIGNAL_GROUP_EXIT) {
1174 spin_unlock(¤t->sighand->siglock);
1175 write_unlock_irq(&tasklist_lock);
1177 goto bad_fork_cleanup_namespace;
1179 p->group_leader = current->group_leader;
1181 if (current->signal->group_stop_count > 0) {
1183 * There is an all-stop in progress for the group.
1184 * We ourselves will stop as soon as we check signals.
1185 * Make the new thread part of that group stop too.
1187 current->signal->group_stop_count++;
1188 set_tsk_thread_flag(p, TIF_SIGPENDING);
1191 if (!cputime_eq(current->signal->it_virt_expires,
1193 !cputime_eq(current->signal->it_prof_expires,
1195 current->signal->rlim[RLIMIT_CPU].rlim_cur != RLIM_INFINITY ||
1196 !list_empty(¤t->signal->cpu_timers[0]) ||
1197 !list_empty(¤t->signal->cpu_timers[1]) ||
1198 !list_empty(¤t->signal->cpu_timers[2])) {
1200 * Have child wake up on its first tick to check
1201 * for process CPU timers.
1203 p->it_prof_expires = jiffies_to_cputime(1);
1210 p->ioprio = current->ioprio;
1213 if (unlikely(p->ptrace & PT_PTRACED))
1214 __ptrace_link(p, current->parent);
1216 if (thread_group_leader(p)) {
1217 p->signal->tty = current->signal->tty;
1218 p->signal->pgrp = process_group(current);
1219 p->signal->session = current->signal->session;
1220 attach_pid(p, PIDTYPE_PGID, process_group(p));
1221 attach_pid(p, PIDTYPE_SID, p->signal->session);
1223 __get_cpu_var(process_counts)++;
1225 attach_pid(p, PIDTYPE_TGID, p->tgid);
1226 attach_pid(p, PIDTYPE_PID, p->pid);
1230 spin_unlock(¤t->sighand->siglock);
1232 /* p is copy of current */
1235 claim_vx_info(vxi, p);
1236 atomic_inc(&vxi->cvirt.nr_threads);
1237 atomic_inc(&vxi->cvirt.total_forks);
1242 claim_nx_info(nxi, p);
1243 write_unlock_irq(&tasklist_lock);
1244 proc_fork_connector(p);
1247 bad_fork_cleanup_namespace:
1249 bad_fork_cleanup_keys:
1251 bad_fork_cleanup_mm:
1254 bad_fork_cleanup_signal:
1256 bad_fork_cleanup_sighand:
1258 bad_fork_cleanup_fs:
1259 exit_fs(p); /* blocking */
1260 bad_fork_cleanup_files:
1261 exit_files(p); /* blocking */
1262 bad_fork_cleanup_semundo:
1264 bad_fork_cleanup_audit:
1266 bad_fork_cleanup_security:
1267 security_task_free(p);
1268 bad_fork_cleanup_policy:
1270 mpol_free(p->mempolicy);
1271 bad_fork_cleanup_cpuset:
1276 module_put(p->binfmt->module);
1277 bad_fork_cleanup_put_domain:
1278 module_put(task_thread_info(p)->exec_domain->module);
1279 bad_fork_cleanup_count:
1280 put_group_info(p->group_info);
1281 atomic_dec(&p->user->processes);
1283 bad_fork_cleanup_vm:
1284 if (p->mm && !(clone_flags & CLONE_VM))
1285 vx_pages_sub(p->vx_info, RLIMIT_AS, p->mm->total_vm);
1289 return ERR_PTR(retval);
1292 struct pt_regs * __devinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1294 memset(regs, 0, sizeof(struct pt_regs));
1298 task_t * __devinit fork_idle(int cpu)
1301 struct pt_regs regs;
1303 task = copy_process(CLONE_VM, 0, idle_regs(®s), 0, NULL, NULL, 0);
1305 return ERR_PTR(-ENOMEM);
1306 init_idle(task, cpu);
1307 unhash_process(task);
1311 static inline int fork_traceflag (unsigned clone_flags)
1313 if (clone_flags & CLONE_UNTRACED)
1315 else if (clone_flags & CLONE_VFORK) {
1316 if (current->ptrace & PT_TRACE_VFORK)
1317 return PTRACE_EVENT_VFORK;
1318 } else if ((clone_flags & CSIGNAL) != SIGCHLD) {
1319 if (current->ptrace & PT_TRACE_CLONE)
1320 return PTRACE_EVENT_CLONE;
1321 } else if (current->ptrace & PT_TRACE_FORK)
1322 return PTRACE_EVENT_FORK;
1328 * Ok, this is the main fork-routine.
1330 * It copies the process, and if successful kick-starts
1331 * it and waits for it to finish using the VM if required.
1333 long do_fork(unsigned long clone_flags,
1334 unsigned long stack_start,
1335 struct pt_regs *regs,
1336 unsigned long stack_size,
1337 int __user *parent_tidptr,
1338 int __user *child_tidptr)
1340 struct task_struct *p;
1342 long pid = alloc_pidmap();
1346 if (unlikely(current->ptrace)) {
1347 trace = fork_traceflag (clone_flags);
1349 clone_flags |= CLONE_PTRACE;
1352 p = copy_process(clone_flags, stack_start, regs, stack_size, parent_tidptr, child_tidptr, pid);
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 if (clone_flags & CLONE_VFORK) {
1361 p->vfork_done = &vfork;
1362 init_completion(&vfork);
1365 if ((p->ptrace & PT_PTRACED) || (clone_flags & CLONE_STOPPED)) {
1367 * We'll start up with an immediate SIGSTOP.
1369 sigaddset(&p->pending.signal, SIGSTOP);
1370 set_tsk_thread_flag(p, TIF_SIGPENDING);
1373 if (!(clone_flags & CLONE_STOPPED))
1374 wake_up_new_task(p, clone_flags);
1376 p->state = TASK_STOPPED;
1378 if (unlikely (trace)) {
1379 current->ptrace_message = pid;
1380 ptrace_notify ((trace << 8) | SIGTRAP);
1383 if (clone_flags & CLONE_VFORK) {
1384 wait_for_completion(&vfork);
1385 if (unlikely (current->ptrace & PT_TRACE_VFORK_DONE))
1386 ptrace_notify ((PTRACE_EVENT_VFORK_DONE << 8) | SIGTRAP);
1395 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1396 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1399 void __init proc_caches_init(void)
1401 sighand_cachep = kmem_cache_create("sighand_cache",
1402 sizeof(struct sighand_struct), 0,
1403 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1404 signal_cachep = kmem_cache_create("signal_cache",
1405 sizeof(struct signal_struct), 0,
1406 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1407 files_cachep = kmem_cache_create("files_cache",
1408 sizeof(struct files_struct), 0,
1409 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1410 fs_cachep = kmem_cache_create("fs_cache",
1411 sizeof(struct fs_struct), 0,
1412 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1413 vm_area_cachep = kmem_cache_create("vm_area_struct",
1414 sizeof(struct vm_area_struct), 0,
1415 SLAB_PANIC, NULL, NULL);
1416 mm_cachep = kmem_cache_create("mm_struct",
1417 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1418 SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL, NULL);
1423 * Check constraints on flags passed to the unshare system call and
1424 * force unsharing of additional process context as appropriate.
1426 static inline void check_unshare_flags(unsigned long *flags_ptr)
1429 * If unsharing a thread from a thread group, must also
1432 if (*flags_ptr & CLONE_THREAD)
1433 *flags_ptr |= CLONE_VM;
1436 * If unsharing vm, must also unshare signal handlers.
1438 if (*flags_ptr & CLONE_VM)
1439 *flags_ptr |= CLONE_SIGHAND;
1442 * If unsharing signal handlers and the task was created
1443 * using CLONE_THREAD, then must unshare the thread
1445 if ((*flags_ptr & CLONE_SIGHAND) &&
1446 (atomic_read(¤t->signal->count) > 1))
1447 *flags_ptr |= CLONE_THREAD;
1450 * If unsharing namespace, must also unshare filesystem information.
1452 if (*flags_ptr & CLONE_NEWNS)
1453 *flags_ptr |= CLONE_FS;
1457 * Unsharing of tasks created with CLONE_THREAD is not supported yet
1459 static int unshare_thread(unsigned long unshare_flags)
1461 if (unshare_flags & CLONE_THREAD)
1468 * Unshare the filesystem structure if it is being shared
1470 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1472 struct fs_struct *fs = current->fs;
1474 if ((unshare_flags & CLONE_FS) &&
1475 (fs && atomic_read(&fs->count) > 1)) {
1476 *new_fsp = __copy_fs_struct(current->fs);
1485 * Unshare the namespace structure if it is being shared
1487 static int unshare_namespace(unsigned long unshare_flags, struct namespace **new_nsp, struct fs_struct *new_fs)
1489 struct namespace *ns = current->namespace;
1491 if ((unshare_flags & CLONE_NEWNS) &&
1492 (ns && atomic_read(&ns->count) > 1)) {
1493 if (!capable(CAP_SYS_ADMIN))
1496 *new_nsp = dup_namespace(current, new_fs ? new_fs : current->fs);
1505 * Unsharing of sighand for tasks created with CLONE_SIGHAND is not
1508 static int unshare_sighand(unsigned long unshare_flags, struct sighand_struct **new_sighp)
1510 struct sighand_struct *sigh = current->sighand;
1512 if ((unshare_flags & CLONE_SIGHAND) &&
1513 (sigh && atomic_read(&sigh->count) > 1))
1520 * Unshare vm if it is being shared
1522 static int unshare_vm(unsigned long unshare_flags, struct mm_struct **new_mmp)
1524 struct mm_struct *mm = current->mm;
1526 if ((unshare_flags & CLONE_VM) &&
1527 (mm && atomic_read(&mm->mm_users) > 1)) {
1535 * Unshare file descriptor table if it is being shared
1537 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1539 struct files_struct *fd = current->files;
1542 if ((unshare_flags & CLONE_FILES) &&
1543 (fd && atomic_read(&fd->count) > 1)) {
1544 *new_fdp = dup_fd(fd, &error);
1553 * Unsharing of semundo for tasks created with CLONE_SYSVSEM is not
1556 static int unshare_semundo(unsigned long unshare_flags, struct sem_undo_list **new_ulistp)
1558 if (unshare_flags & CLONE_SYSVSEM)
1565 * unshare allows a process to 'unshare' part of the process
1566 * context which was originally shared using clone. copy_*
1567 * functions used by do_fork() cannot be used here directly
1568 * because they modify an inactive task_struct that is being
1569 * constructed. Here we are modifying the current, active,
1572 asmlinkage long sys_unshare(unsigned long unshare_flags)
1575 struct fs_struct *fs, *new_fs = NULL;
1576 struct namespace *ns, *new_ns = NULL;
1577 struct sighand_struct *sigh, *new_sigh = NULL;
1578 struct mm_struct *mm, *new_mm = NULL, *active_mm = NULL;
1579 struct files_struct *fd, *new_fd = NULL;
1580 struct sem_undo_list *new_ulist = NULL;
1582 check_unshare_flags(&unshare_flags);
1584 if ((err = unshare_thread(unshare_flags)))
1585 goto bad_unshare_out;
1586 if ((err = unshare_fs(unshare_flags, &new_fs)))
1587 goto bad_unshare_cleanup_thread;
1588 if ((err = unshare_namespace(unshare_flags, &new_ns, new_fs)))
1589 goto bad_unshare_cleanup_fs;
1590 if ((err = unshare_sighand(unshare_flags, &new_sigh)))
1591 goto bad_unshare_cleanup_ns;
1592 if ((err = unshare_vm(unshare_flags, &new_mm)))
1593 goto bad_unshare_cleanup_sigh;
1594 if ((err = unshare_fd(unshare_flags, &new_fd)))
1595 goto bad_unshare_cleanup_vm;
1596 if ((err = unshare_semundo(unshare_flags, &new_ulist)))
1597 goto bad_unshare_cleanup_fd;
1599 if (new_fs || new_ns || new_sigh || new_mm || new_fd || new_ulist) {
1605 current->fs = new_fs;
1610 ns = current->namespace;
1611 current->namespace = new_ns;
1616 sigh = current->sighand;
1617 rcu_assign_pointer(current->sighand, new_sigh);
1623 active_mm = current->active_mm;
1624 current->mm = new_mm;
1625 current->active_mm = new_mm;
1626 activate_mm(active_mm, new_mm);
1631 fd = current->files;
1632 current->files = new_fd;
1636 task_unlock(current);
1639 bad_unshare_cleanup_fd:
1641 put_files_struct(new_fd);
1643 bad_unshare_cleanup_vm:
1647 bad_unshare_cleanup_sigh:
1649 if (atomic_dec_and_test(&new_sigh->count))
1650 kmem_cache_free(sighand_cachep, new_sigh);
1652 bad_unshare_cleanup_ns:
1654 put_namespace(new_ns);
1656 bad_unshare_cleanup_fs:
1658 put_fs_struct(new_fs);
1660 bad_unshare_cleanup_thread: