Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jlbec...
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / fork.c
blobca406d916713696c66e2a47b60cfd5d7a615f711
1 /*
2 * linux/kernel/fork.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 /*
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/personality.h>
21 #include <linux/mempolicy.h>
22 #include <linux/sem.h>
23 #include <linux/file.h>
24 #include <linux/fdtable.h>
25 #include <linux/iocontext.h>
26 #include <linux/key.h>
27 #include <linux/binfmts.h>
28 #include <linux/mman.h>
29 #include <linux/mmu_notifier.h>
30 #include <linux/fs.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/tracehook.h>
41 #include <linux/futex.h>
42 #include <linux/compat.h>
43 #include <linux/kthread.h>
44 #include <linux/task_io_accounting_ops.h>
45 #include <linux/rcupdate.h>
46 #include <linux/ptrace.h>
47 #include <linux/mount.h>
48 #include <linux/audit.h>
49 #include <linux/memcontrol.h>
50 #include <linux/ftrace.h>
51 #include <linux/profile.h>
52 #include <linux/rmap.h>
53 #include <linux/ksm.h>
54 #include <linux/acct.h>
55 #include <linux/tsacct_kern.h>
56 #include <linux/cn_proc.h>
57 #include <linux/freezer.h>
58 #include <linux/delayacct.h>
59 #include <linux/taskstats_kern.h>
60 #include <linux/random.h>
61 #include <linux/tty.h>
62 #include <linux/blkdev.h>
63 #include <linux/fs_struct.h>
64 #include <linux/magic.h>
65 #include <linux/perf_event.h>
66 #include <linux/posix-timers.h>
67 #include <linux/user-return-notifier.h>
68 #include <linux/oom.h>
69 #include <linux/khugepaged.h>
71 #include <asm/pgtable.h>
72 #include <asm/pgalloc.h>
73 #include <asm/uaccess.h>
74 #include <asm/mmu_context.h>
75 #include <asm/cacheflush.h>
76 #include <asm/tlbflush.h>
78 #include <trace/events/sched.h>
81 * Protected counters by write_lock_irq(&tasklist_lock)
83 unsigned long total_forks; /* Handle normal Linux uptimes. */
84 int nr_threads; /* The idle threads do not count.. */
86 int max_threads; /* tunable limit on nr_threads */
88 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
90 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
92 #ifdef CONFIG_PROVE_RCU
93 int lockdep_tasklist_lock_is_held(void)
95 return lockdep_is_held(&tasklist_lock);
97 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
98 #endif /* #ifdef CONFIG_PROVE_RCU */
100 int nr_processes(void)
102 int cpu;
103 int total = 0;
105 for_each_possible_cpu(cpu)
106 total += per_cpu(process_counts, cpu);
108 return total;
111 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
112 # define alloc_task_struct_node(node) \
113 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
114 # define free_task_struct(tsk) \
115 kmem_cache_free(task_struct_cachep, (tsk))
116 static struct kmem_cache *task_struct_cachep;
117 #endif
119 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
120 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
121 int node)
123 #ifdef CONFIG_DEBUG_STACK_USAGE
124 gfp_t mask = GFP_KERNEL | __GFP_ZERO;
125 #else
126 gfp_t mask = GFP_KERNEL;
127 #endif
128 struct page *page = alloc_pages_node(node, mask, THREAD_SIZE_ORDER);
130 return page ? page_address(page) : NULL;
133 static inline void free_thread_info(struct thread_info *ti)
135 free_pages((unsigned long)ti, THREAD_SIZE_ORDER);
137 #endif
139 /* SLAB cache for signal_struct structures (tsk->signal) */
140 static struct kmem_cache *signal_cachep;
142 /* SLAB cache for sighand_struct structures (tsk->sighand) */
143 struct kmem_cache *sighand_cachep;
145 /* SLAB cache for files_struct structures (tsk->files) */
146 struct kmem_cache *files_cachep;
148 /* SLAB cache for fs_struct structures (tsk->fs) */
149 struct kmem_cache *fs_cachep;
151 /* SLAB cache for vm_area_struct structures */
152 struct kmem_cache *vm_area_cachep;
154 /* SLAB cache for mm_struct structures (tsk->mm) */
155 static struct kmem_cache *mm_cachep;
157 static void account_kernel_stack(struct thread_info *ti, int account)
159 struct zone *zone = page_zone(virt_to_page(ti));
161 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
164 void free_task(struct task_struct *tsk)
166 prop_local_destroy_single(&tsk->dirties);
167 account_kernel_stack(tsk->stack, -1);
168 free_thread_info(tsk->stack);
169 rt_mutex_debug_task_free(tsk);
170 ftrace_graph_exit_task(tsk);
171 free_task_struct(tsk);
173 EXPORT_SYMBOL(free_task);
175 static inline void free_signal_struct(struct signal_struct *sig)
177 taskstats_tgid_free(sig);
178 sched_autogroup_exit(sig);
179 kmem_cache_free(signal_cachep, sig);
182 static inline void put_signal_struct(struct signal_struct *sig)
184 if (atomic_dec_and_test(&sig->sigcnt))
185 free_signal_struct(sig);
188 void __put_task_struct(struct task_struct *tsk)
190 WARN_ON(!tsk->exit_state);
191 WARN_ON(atomic_read(&tsk->usage));
192 WARN_ON(tsk == current);
194 exit_creds(tsk);
195 delayacct_tsk_free(tsk);
196 put_signal_struct(tsk->signal);
198 if (!profile_handoff_task(tsk))
199 free_task(tsk);
201 EXPORT_SYMBOL_GPL(__put_task_struct);
204 * macro override instead of weak attribute alias, to workaround
205 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
207 #ifndef arch_task_cache_init
208 #define arch_task_cache_init()
209 #endif
211 void __init fork_init(unsigned long mempages)
213 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
214 #ifndef ARCH_MIN_TASKALIGN
215 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
216 #endif
217 /* create a slab on which task_structs can be allocated */
218 task_struct_cachep =
219 kmem_cache_create("task_struct", sizeof(struct task_struct),
220 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
221 #endif
223 /* do the arch specific task caches init */
224 arch_task_cache_init();
227 * The default maximum number of threads is set to a safe
228 * value: the thread structures can take up at most half
229 * of memory.
231 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
234 * we need to allow at least 20 threads to boot a system
236 if(max_threads < 20)
237 max_threads = 20;
239 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
240 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
241 init_task.signal->rlim[RLIMIT_SIGPENDING] =
242 init_task.signal->rlim[RLIMIT_NPROC];
245 int __attribute__((weak)) arch_dup_task_struct(struct task_struct *dst,
246 struct task_struct *src)
248 *dst = *src;
249 return 0;
252 static struct task_struct *dup_task_struct(struct task_struct *orig)
254 struct task_struct *tsk;
255 struct thread_info *ti;
256 unsigned long *stackend;
257 int node = tsk_fork_get_node(orig);
258 int err;
260 prepare_to_copy(orig);
262 tsk = alloc_task_struct_node(node);
263 if (!tsk)
264 return NULL;
266 ti = alloc_thread_info_node(tsk, node);
267 if (!ti) {
268 free_task_struct(tsk);
269 return NULL;
272 err = arch_dup_task_struct(tsk, orig);
273 if (err)
274 goto out;
276 tsk->stack = ti;
278 err = prop_local_init_single(&tsk->dirties);
279 if (err)
280 goto out;
282 setup_thread_stack(tsk, orig);
283 clear_user_return_notifier(tsk);
284 clear_tsk_need_resched(tsk);
285 stackend = end_of_stack(tsk);
286 *stackend = STACK_END_MAGIC; /* for overflow detection */
288 #ifdef CONFIG_CC_STACKPROTECTOR
289 tsk->stack_canary = get_random_int();
290 #endif
292 /* One for us, one for whoever does the "release_task()" (usually parent) */
293 atomic_set(&tsk->usage,2);
294 atomic_set(&tsk->fs_excl, 0);
295 #ifdef CONFIG_BLK_DEV_IO_TRACE
296 tsk->btrace_seq = 0;
297 #endif
298 tsk->splice_pipe = NULL;
300 account_kernel_stack(ti, 1);
302 return tsk;
304 out:
305 free_thread_info(ti);
306 free_task_struct(tsk);
307 return NULL;
310 #ifdef CONFIG_MMU
311 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
313 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
314 struct rb_node **rb_link, *rb_parent;
315 int retval;
316 unsigned long charge;
317 struct mempolicy *pol;
319 down_write(&oldmm->mmap_sem);
320 flush_cache_dup_mm(oldmm);
322 * Not linked in yet - no deadlock potential:
324 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
326 mm->locked_vm = 0;
327 mm->mmap = NULL;
328 mm->mmap_cache = NULL;
329 mm->free_area_cache = oldmm->mmap_base;
330 mm->cached_hole_size = ~0UL;
331 mm->map_count = 0;
332 cpumask_clear(mm_cpumask(mm));
333 mm->mm_rb = RB_ROOT;
334 rb_link = &mm->mm_rb.rb_node;
335 rb_parent = NULL;
336 pprev = &mm->mmap;
337 retval = ksm_fork(mm, oldmm);
338 if (retval)
339 goto out;
340 retval = khugepaged_fork(mm, oldmm);
341 if (retval)
342 goto out;
344 prev = NULL;
345 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
346 struct file *file;
348 if (mpnt->vm_flags & VM_DONTCOPY) {
349 long pages = vma_pages(mpnt);
350 mm->total_vm -= pages;
351 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
352 -pages);
353 continue;
355 charge = 0;
356 if (mpnt->vm_flags & VM_ACCOUNT) {
357 unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT;
358 if (security_vm_enough_memory(len))
359 goto fail_nomem;
360 charge = len;
362 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
363 if (!tmp)
364 goto fail_nomem;
365 *tmp = *mpnt;
366 INIT_LIST_HEAD(&tmp->anon_vma_chain);
367 pol = mpol_dup(vma_policy(mpnt));
368 retval = PTR_ERR(pol);
369 if (IS_ERR(pol))
370 goto fail_nomem_policy;
371 vma_set_policy(tmp, pol);
372 tmp->vm_mm = mm;
373 if (anon_vma_fork(tmp, mpnt))
374 goto fail_nomem_anon_vma_fork;
375 tmp->vm_flags &= ~VM_LOCKED;
376 tmp->vm_next = tmp->vm_prev = NULL;
377 file = tmp->vm_file;
378 if (file) {
379 struct inode *inode = file->f_path.dentry->d_inode;
380 struct address_space *mapping = file->f_mapping;
382 get_file(file);
383 if (tmp->vm_flags & VM_DENYWRITE)
384 atomic_dec(&inode->i_writecount);
385 mutex_lock(&mapping->i_mmap_mutex);
386 if (tmp->vm_flags & VM_SHARED)
387 mapping->i_mmap_writable++;
388 flush_dcache_mmap_lock(mapping);
389 /* insert tmp into the share list, just after mpnt */
390 vma_prio_tree_add(tmp, mpnt);
391 flush_dcache_mmap_unlock(mapping);
392 mutex_unlock(&mapping->i_mmap_mutex);
396 * Clear hugetlb-related page reserves for children. This only
397 * affects MAP_PRIVATE mappings. Faults generated by the child
398 * are not guaranteed to succeed, even if read-only
400 if (is_vm_hugetlb_page(tmp))
401 reset_vma_resv_huge_pages(tmp);
404 * Link in the new vma and copy the page table entries.
406 *pprev = tmp;
407 pprev = &tmp->vm_next;
408 tmp->vm_prev = prev;
409 prev = tmp;
411 __vma_link_rb(mm, tmp, rb_link, rb_parent);
412 rb_link = &tmp->vm_rb.rb_right;
413 rb_parent = &tmp->vm_rb;
415 mm->map_count++;
416 retval = copy_page_range(mm, oldmm, mpnt);
418 if (tmp->vm_ops && tmp->vm_ops->open)
419 tmp->vm_ops->open(tmp);
421 if (retval)
422 goto out;
424 /* a new mm has just been created */
425 arch_dup_mmap(oldmm, mm);
426 retval = 0;
427 out:
428 up_write(&mm->mmap_sem);
429 flush_tlb_mm(oldmm);
430 up_write(&oldmm->mmap_sem);
431 return retval;
432 fail_nomem_anon_vma_fork:
433 mpol_put(pol);
434 fail_nomem_policy:
435 kmem_cache_free(vm_area_cachep, tmp);
436 fail_nomem:
437 retval = -ENOMEM;
438 vm_unacct_memory(charge);
439 goto out;
442 static inline int mm_alloc_pgd(struct mm_struct * mm)
444 mm->pgd = pgd_alloc(mm);
445 if (unlikely(!mm->pgd))
446 return -ENOMEM;
447 return 0;
450 static inline void mm_free_pgd(struct mm_struct * mm)
452 pgd_free(mm, mm->pgd);
454 #else
455 #define dup_mmap(mm, oldmm) (0)
456 #define mm_alloc_pgd(mm) (0)
457 #define mm_free_pgd(mm)
458 #endif /* CONFIG_MMU */
460 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
462 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
463 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
465 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
467 static int __init coredump_filter_setup(char *s)
469 default_dump_filter =
470 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
471 MMF_DUMP_FILTER_MASK;
472 return 1;
475 __setup("coredump_filter=", coredump_filter_setup);
477 #include <linux/init_task.h>
479 static void mm_init_aio(struct mm_struct *mm)
481 #ifdef CONFIG_AIO
482 spin_lock_init(&mm->ioctx_lock);
483 INIT_HLIST_HEAD(&mm->ioctx_list);
484 #endif
487 int mm_init_cpumask(struct mm_struct *mm, struct mm_struct *oldmm)
489 #ifdef CONFIG_CPUMASK_OFFSTACK
490 if (!alloc_cpumask_var(&mm->cpu_vm_mask_var, GFP_KERNEL))
491 return -ENOMEM;
493 if (oldmm)
494 cpumask_copy(mm_cpumask(mm), mm_cpumask(oldmm));
495 else
496 memset(mm_cpumask(mm), 0, cpumask_size());
497 #endif
498 return 0;
501 static struct mm_struct * mm_init(struct mm_struct * mm, struct task_struct *p)
503 atomic_set(&mm->mm_users, 1);
504 atomic_set(&mm->mm_count, 1);
505 init_rwsem(&mm->mmap_sem);
506 INIT_LIST_HEAD(&mm->mmlist);
507 mm->flags = (current->mm) ?
508 (current->mm->flags & MMF_INIT_MASK) : default_dump_filter;
509 mm->core_state = NULL;
510 mm->nr_ptes = 0;
511 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
512 spin_lock_init(&mm->page_table_lock);
513 mm->free_area_cache = TASK_UNMAPPED_BASE;
514 mm->cached_hole_size = ~0UL;
515 mm_init_aio(mm);
516 mm_init_owner(mm, p);
517 atomic_set(&mm->oom_disable_count, 0);
519 if (likely(!mm_alloc_pgd(mm))) {
520 mm->def_flags = 0;
521 mmu_notifier_mm_init(mm);
522 return mm;
525 free_mm(mm);
526 return NULL;
530 * Allocate and initialize an mm_struct.
532 struct mm_struct * mm_alloc(void)
534 struct mm_struct * mm;
536 mm = allocate_mm();
537 if (!mm)
538 return NULL;
540 memset(mm, 0, sizeof(*mm));
541 mm = mm_init(mm, current);
542 if (!mm)
543 return NULL;
545 if (mm_init_cpumask(mm, NULL)) {
546 mm_free_pgd(mm);
547 free_mm(mm);
548 return NULL;
551 return mm;
555 * Called when the last reference to the mm
556 * is dropped: either by a lazy thread or by
557 * mmput. Free the page directory and the mm.
559 void __mmdrop(struct mm_struct *mm)
561 BUG_ON(mm == &init_mm);
562 free_cpumask_var(mm->cpu_vm_mask_var);
563 mm_free_pgd(mm);
564 destroy_context(mm);
565 mmu_notifier_mm_destroy(mm);
566 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
567 VM_BUG_ON(mm->pmd_huge_pte);
568 #endif
569 free_mm(mm);
571 EXPORT_SYMBOL_GPL(__mmdrop);
574 * Decrement the use count and release all resources for an mm.
576 void mmput(struct mm_struct *mm)
578 might_sleep();
580 if (atomic_dec_and_test(&mm->mm_users)) {
581 exit_aio(mm);
582 ksm_exit(mm);
583 khugepaged_exit(mm); /* must run before exit_mmap */
584 exit_mmap(mm);
585 set_mm_exe_file(mm, NULL);
586 if (!list_empty(&mm->mmlist)) {
587 spin_lock(&mmlist_lock);
588 list_del(&mm->mmlist);
589 spin_unlock(&mmlist_lock);
591 put_swap_token(mm);
592 if (mm->binfmt)
593 module_put(mm->binfmt->module);
594 mmdrop(mm);
597 EXPORT_SYMBOL_GPL(mmput);
600 * We added or removed a vma mapping the executable. The vmas are only mapped
601 * during exec and are not mapped with the mmap system call.
602 * Callers must hold down_write() on the mm's mmap_sem for these
604 void added_exe_file_vma(struct mm_struct *mm)
606 mm->num_exe_file_vmas++;
609 void removed_exe_file_vma(struct mm_struct *mm)
611 mm->num_exe_file_vmas--;
612 if ((mm->num_exe_file_vmas == 0) && mm->exe_file){
613 fput(mm->exe_file);
614 mm->exe_file = NULL;
619 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
621 if (new_exe_file)
622 get_file(new_exe_file);
623 if (mm->exe_file)
624 fput(mm->exe_file);
625 mm->exe_file = new_exe_file;
626 mm->num_exe_file_vmas = 0;
629 struct file *get_mm_exe_file(struct mm_struct *mm)
631 struct file *exe_file;
633 /* We need mmap_sem to protect against races with removal of
634 * VM_EXECUTABLE vmas */
635 down_read(&mm->mmap_sem);
636 exe_file = mm->exe_file;
637 if (exe_file)
638 get_file(exe_file);
639 up_read(&mm->mmap_sem);
640 return exe_file;
643 static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
645 /* It's safe to write the exe_file pointer without exe_file_lock because
646 * this is called during fork when the task is not yet in /proc */
647 newmm->exe_file = get_mm_exe_file(oldmm);
651 * get_task_mm - acquire a reference to the task's mm
653 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
654 * this kernel workthread has transiently adopted a user mm with use_mm,
655 * to do its AIO) is not set and if so returns a reference to it, after
656 * bumping up the use count. User must release the mm via mmput()
657 * after use. Typically used by /proc and ptrace.
659 struct mm_struct *get_task_mm(struct task_struct *task)
661 struct mm_struct *mm;
663 task_lock(task);
664 mm = task->mm;
665 if (mm) {
666 if (task->flags & PF_KTHREAD)
667 mm = NULL;
668 else
669 atomic_inc(&mm->mm_users);
671 task_unlock(task);
672 return mm;
674 EXPORT_SYMBOL_GPL(get_task_mm);
676 /* Please note the differences between mmput and mm_release.
677 * mmput is called whenever we stop holding onto a mm_struct,
678 * error success whatever.
680 * mm_release is called after a mm_struct has been removed
681 * from the current process.
683 * This difference is important for error handling, when we
684 * only half set up a mm_struct for a new process and need to restore
685 * the old one. Because we mmput the new mm_struct before
686 * restoring the old one. . .
687 * Eric Biederman 10 January 1998
689 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
691 struct completion *vfork_done = tsk->vfork_done;
693 /* Get rid of any futexes when releasing the mm */
694 #ifdef CONFIG_FUTEX
695 if (unlikely(tsk->robust_list)) {
696 exit_robust_list(tsk);
697 tsk->robust_list = NULL;
699 #ifdef CONFIG_COMPAT
700 if (unlikely(tsk->compat_robust_list)) {
701 compat_exit_robust_list(tsk);
702 tsk->compat_robust_list = NULL;
704 #endif
705 if (unlikely(!list_empty(&tsk->pi_state_list)))
706 exit_pi_state_list(tsk);
707 #endif
709 /* Get rid of any cached register state */
710 deactivate_mm(tsk, mm);
712 /* notify parent sleeping on vfork() */
713 if (vfork_done) {
714 tsk->vfork_done = NULL;
715 complete(vfork_done);
719 * If we're exiting normally, clear a user-space tid field if
720 * requested. We leave this alone when dying by signal, to leave
721 * the value intact in a core dump, and to save the unnecessary
722 * trouble otherwise. Userland only wants this done for a sys_exit.
724 if (tsk->clear_child_tid) {
725 if (!(tsk->flags & PF_SIGNALED) &&
726 atomic_read(&mm->mm_users) > 1) {
728 * We don't check the error code - if userspace has
729 * not set up a proper pointer then tough luck.
731 put_user(0, tsk->clear_child_tid);
732 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
733 1, NULL, NULL, 0);
735 tsk->clear_child_tid = NULL;
740 * Allocate a new mm structure and copy contents from the
741 * mm structure of the passed in task structure.
743 struct mm_struct *dup_mm(struct task_struct *tsk)
745 struct mm_struct *mm, *oldmm = current->mm;
746 int err;
748 if (!oldmm)
749 return NULL;
751 mm = allocate_mm();
752 if (!mm)
753 goto fail_nomem;
755 memcpy(mm, oldmm, sizeof(*mm));
757 /* Initializing for Swap token stuff */
758 mm->token_priority = 0;
759 mm->last_interval = 0;
761 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
762 mm->pmd_huge_pte = NULL;
763 #endif
765 if (!mm_init(mm, tsk))
766 goto fail_nomem;
768 if (mm_init_cpumask(mm, oldmm))
769 goto fail_nocpumask;
771 if (init_new_context(tsk, mm))
772 goto fail_nocontext;
774 dup_mm_exe_file(oldmm, mm);
776 err = dup_mmap(mm, oldmm);
777 if (err)
778 goto free_pt;
780 mm->hiwater_rss = get_mm_rss(mm);
781 mm->hiwater_vm = mm->total_vm;
783 if (mm->binfmt && !try_module_get(mm->binfmt->module))
784 goto free_pt;
786 return mm;
788 free_pt:
789 /* don't put binfmt in mmput, we haven't got module yet */
790 mm->binfmt = NULL;
791 mmput(mm);
793 fail_nomem:
794 return NULL;
796 fail_nocontext:
797 free_cpumask_var(mm->cpu_vm_mask_var);
799 fail_nocpumask:
801 * If init_new_context() failed, we cannot use mmput() to free the mm
802 * because it calls destroy_context()
804 mm_free_pgd(mm);
805 free_mm(mm);
806 return NULL;
809 static int copy_mm(unsigned long clone_flags, struct task_struct * tsk)
811 struct mm_struct * mm, *oldmm;
812 int retval;
814 tsk->min_flt = tsk->maj_flt = 0;
815 tsk->nvcsw = tsk->nivcsw = 0;
816 #ifdef CONFIG_DETECT_HUNG_TASK
817 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
818 #endif
820 tsk->mm = NULL;
821 tsk->active_mm = NULL;
824 * Are we cloning a kernel thread?
826 * We need to steal a active VM for that..
828 oldmm = current->mm;
829 if (!oldmm)
830 return 0;
832 if (clone_flags & CLONE_VM) {
833 atomic_inc(&oldmm->mm_users);
834 mm = oldmm;
835 goto good_mm;
838 retval = -ENOMEM;
839 mm = dup_mm(tsk);
840 if (!mm)
841 goto fail_nomem;
843 good_mm:
844 /* Initializing for Swap token stuff */
845 mm->token_priority = 0;
846 mm->last_interval = 0;
847 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
848 atomic_inc(&mm->oom_disable_count);
850 tsk->mm = mm;
851 tsk->active_mm = mm;
852 return 0;
854 fail_nomem:
855 return retval;
858 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
860 struct fs_struct *fs = current->fs;
861 if (clone_flags & CLONE_FS) {
862 /* tsk->fs is already what we want */
863 spin_lock(&fs->lock);
864 if (fs->in_exec) {
865 spin_unlock(&fs->lock);
866 return -EAGAIN;
868 fs->users++;
869 spin_unlock(&fs->lock);
870 return 0;
872 tsk->fs = copy_fs_struct(fs);
873 if (!tsk->fs)
874 return -ENOMEM;
875 return 0;
878 static int copy_files(unsigned long clone_flags, struct task_struct * tsk)
880 struct files_struct *oldf, *newf;
881 int error = 0;
884 * A background process may not have any files ...
886 oldf = current->files;
887 if (!oldf)
888 goto out;
890 if (clone_flags & CLONE_FILES) {
891 atomic_inc(&oldf->count);
892 goto out;
895 newf = dup_fd(oldf, &error);
896 if (!newf)
897 goto out;
899 tsk->files = newf;
900 error = 0;
901 out:
902 return error;
905 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
907 #ifdef CONFIG_BLOCK
908 struct io_context *ioc = current->io_context;
910 if (!ioc)
911 return 0;
913 * Share io context with parent, if CLONE_IO is set
915 if (clone_flags & CLONE_IO) {
916 tsk->io_context = ioc_task_link(ioc);
917 if (unlikely(!tsk->io_context))
918 return -ENOMEM;
919 } else if (ioprio_valid(ioc->ioprio)) {
920 tsk->io_context = alloc_io_context(GFP_KERNEL, -1);
921 if (unlikely(!tsk->io_context))
922 return -ENOMEM;
924 tsk->io_context->ioprio = ioc->ioprio;
926 #endif
927 return 0;
930 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
932 struct sighand_struct *sig;
934 if (clone_flags & CLONE_SIGHAND) {
935 atomic_inc(&current->sighand->count);
936 return 0;
938 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
939 rcu_assign_pointer(tsk->sighand, sig);
940 if (!sig)
941 return -ENOMEM;
942 atomic_set(&sig->count, 1);
943 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
944 return 0;
947 void __cleanup_sighand(struct sighand_struct *sighand)
949 if (atomic_dec_and_test(&sighand->count))
950 kmem_cache_free(sighand_cachep, sighand);
955 * Initialize POSIX timer handling for a thread group.
957 static void posix_cpu_timers_init_group(struct signal_struct *sig)
959 unsigned long cpu_limit;
961 /* Thread group counters. */
962 thread_group_cputime_init(sig);
964 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
965 if (cpu_limit != RLIM_INFINITY) {
966 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
967 sig->cputimer.running = 1;
970 /* The timer lists. */
971 INIT_LIST_HEAD(&sig->cpu_timers[0]);
972 INIT_LIST_HEAD(&sig->cpu_timers[1]);
973 INIT_LIST_HEAD(&sig->cpu_timers[2]);
976 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
978 struct signal_struct *sig;
980 if (clone_flags & CLONE_THREAD)
981 return 0;
983 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
984 tsk->signal = sig;
985 if (!sig)
986 return -ENOMEM;
988 sig->nr_threads = 1;
989 atomic_set(&sig->live, 1);
990 atomic_set(&sig->sigcnt, 1);
991 init_waitqueue_head(&sig->wait_chldexit);
992 if (clone_flags & CLONE_NEWPID)
993 sig->flags |= SIGNAL_UNKILLABLE;
994 sig->curr_target = tsk;
995 init_sigpending(&sig->shared_pending);
996 INIT_LIST_HEAD(&sig->posix_timers);
998 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
999 sig->real_timer.function = it_real_fn;
1001 task_lock(current->group_leader);
1002 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1003 task_unlock(current->group_leader);
1005 posix_cpu_timers_init_group(sig);
1007 tty_audit_fork(sig);
1008 sched_autogroup_fork(sig);
1010 #ifdef CONFIG_CGROUPS
1011 init_rwsem(&sig->threadgroup_fork_lock);
1012 #endif
1014 sig->oom_adj = current->signal->oom_adj;
1015 sig->oom_score_adj = current->signal->oom_score_adj;
1016 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1018 mutex_init(&sig->cred_guard_mutex);
1020 return 0;
1023 static void copy_flags(unsigned long clone_flags, struct task_struct *p)
1025 unsigned long new_flags = p->flags;
1027 new_flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
1028 new_flags |= PF_FORKNOEXEC;
1029 new_flags |= PF_STARTING;
1030 p->flags = new_flags;
1031 clear_freeze_flag(p);
1034 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1036 current->clear_child_tid = tidptr;
1038 return task_pid_vnr(current);
1041 static void rt_mutex_init_task(struct task_struct *p)
1043 raw_spin_lock_init(&p->pi_lock);
1044 #ifdef CONFIG_RT_MUTEXES
1045 plist_head_init_raw(&p->pi_waiters, &p->pi_lock);
1046 p->pi_blocked_on = NULL;
1047 #endif
1050 #ifdef CONFIG_MM_OWNER
1051 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1053 mm->owner = p;
1055 #endif /* CONFIG_MM_OWNER */
1058 * Initialize POSIX timer handling for a single task.
1060 static void posix_cpu_timers_init(struct task_struct *tsk)
1062 tsk->cputime_expires.prof_exp = cputime_zero;
1063 tsk->cputime_expires.virt_exp = cputime_zero;
1064 tsk->cputime_expires.sched_exp = 0;
1065 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1066 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1067 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1071 * This creates a new process as a copy of the old one,
1072 * but does not actually start it yet.
1074 * It copies the registers, and all the appropriate
1075 * parts of the process environment (as per the clone
1076 * flags). The actual kick-off is left to the caller.
1078 static struct task_struct *copy_process(unsigned long clone_flags,
1079 unsigned long stack_start,
1080 struct pt_regs *regs,
1081 unsigned long stack_size,
1082 int __user *child_tidptr,
1083 struct pid *pid,
1084 int trace)
1086 int retval;
1087 struct task_struct *p;
1088 int cgroup_callbacks_done = 0;
1090 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1091 return ERR_PTR(-EINVAL);
1094 * Thread groups must share signals as well, and detached threads
1095 * can only be started up within the thread group.
1097 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1098 return ERR_PTR(-EINVAL);
1101 * Shared signal handlers imply shared VM. By way of the above,
1102 * thread groups also imply shared VM. Blocking this case allows
1103 * for various simplifications in other code.
1105 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1106 return ERR_PTR(-EINVAL);
1109 * Siblings of global init remain as zombies on exit since they are
1110 * not reaped by their parent (swapper). To solve this and to avoid
1111 * multi-rooted process trees, prevent global and container-inits
1112 * from creating siblings.
1114 if ((clone_flags & CLONE_PARENT) &&
1115 current->signal->flags & SIGNAL_UNKILLABLE)
1116 return ERR_PTR(-EINVAL);
1118 retval = security_task_create(clone_flags);
1119 if (retval)
1120 goto fork_out;
1122 retval = -ENOMEM;
1123 p = dup_task_struct(current);
1124 if (!p)
1125 goto fork_out;
1127 ftrace_graph_init_task(p);
1129 rt_mutex_init_task(p);
1131 #ifdef CONFIG_PROVE_LOCKING
1132 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1133 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1134 #endif
1135 retval = -EAGAIN;
1136 if (atomic_read(&p->real_cred->user->processes) >=
1137 task_rlimit(p, RLIMIT_NPROC)) {
1138 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_RESOURCE) &&
1139 p->real_cred->user != INIT_USER)
1140 goto bad_fork_free;
1143 retval = copy_creds(p, clone_flags);
1144 if (retval < 0)
1145 goto bad_fork_free;
1148 * If multiple threads are within copy_process(), then this check
1149 * triggers too late. This doesn't hurt, the check is only there
1150 * to stop root fork bombs.
1152 retval = -EAGAIN;
1153 if (nr_threads >= max_threads)
1154 goto bad_fork_cleanup_count;
1156 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1157 goto bad_fork_cleanup_count;
1159 p->did_exec = 0;
1160 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1161 copy_flags(clone_flags, p);
1162 INIT_LIST_HEAD(&p->children);
1163 INIT_LIST_HEAD(&p->sibling);
1164 rcu_copy_process(p);
1165 p->vfork_done = NULL;
1166 spin_lock_init(&p->alloc_lock);
1168 init_sigpending(&p->pending);
1170 p->utime = cputime_zero;
1171 p->stime = cputime_zero;
1172 p->gtime = cputime_zero;
1173 p->utimescaled = cputime_zero;
1174 p->stimescaled = cputime_zero;
1175 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1176 p->prev_utime = cputime_zero;
1177 p->prev_stime = cputime_zero;
1178 #endif
1179 #if defined(SPLIT_RSS_COUNTING)
1180 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1181 #endif
1183 p->default_timer_slack_ns = current->timer_slack_ns;
1185 task_io_accounting_init(&p->ioac);
1186 acct_clear_integrals(p);
1188 posix_cpu_timers_init(p);
1190 do_posix_clock_monotonic_gettime(&p->start_time);
1191 p->real_start_time = p->start_time;
1192 monotonic_to_bootbased(&p->real_start_time);
1193 p->io_context = NULL;
1194 p->audit_context = NULL;
1195 if (clone_flags & CLONE_THREAD)
1196 threadgroup_fork_read_lock(current);
1197 cgroup_fork(p);
1198 #ifdef CONFIG_NUMA
1199 p->mempolicy = mpol_dup(p->mempolicy);
1200 if (IS_ERR(p->mempolicy)) {
1201 retval = PTR_ERR(p->mempolicy);
1202 p->mempolicy = NULL;
1203 goto bad_fork_cleanup_cgroup;
1205 mpol_fix_fork_child_flag(p);
1206 #endif
1207 #ifdef CONFIG_TRACE_IRQFLAGS
1208 p->irq_events = 0;
1209 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1210 p->hardirqs_enabled = 1;
1211 #else
1212 p->hardirqs_enabled = 0;
1213 #endif
1214 p->hardirq_enable_ip = 0;
1215 p->hardirq_enable_event = 0;
1216 p->hardirq_disable_ip = _THIS_IP_;
1217 p->hardirq_disable_event = 0;
1218 p->softirqs_enabled = 1;
1219 p->softirq_enable_ip = _THIS_IP_;
1220 p->softirq_enable_event = 0;
1221 p->softirq_disable_ip = 0;
1222 p->softirq_disable_event = 0;
1223 p->hardirq_context = 0;
1224 p->softirq_context = 0;
1225 #endif
1226 #ifdef CONFIG_LOCKDEP
1227 p->lockdep_depth = 0; /* no locks held yet */
1228 p->curr_chain_key = 0;
1229 p->lockdep_recursion = 0;
1230 #endif
1232 #ifdef CONFIG_DEBUG_MUTEXES
1233 p->blocked_on = NULL; /* not blocked yet */
1234 #endif
1235 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1236 p->memcg_batch.do_batch = 0;
1237 p->memcg_batch.memcg = NULL;
1238 #endif
1240 /* Perform scheduler related setup. Assign this task to a CPU. */
1241 sched_fork(p);
1243 retval = perf_event_init_task(p);
1244 if (retval)
1245 goto bad_fork_cleanup_policy;
1247 if ((retval = audit_alloc(p)))
1248 goto bad_fork_cleanup_policy;
1249 /* copy all the process information */
1250 if ((retval = copy_semundo(clone_flags, p)))
1251 goto bad_fork_cleanup_audit;
1252 if ((retval = copy_files(clone_flags, p)))
1253 goto bad_fork_cleanup_semundo;
1254 if ((retval = copy_fs(clone_flags, p)))
1255 goto bad_fork_cleanup_files;
1256 if ((retval = copy_sighand(clone_flags, p)))
1257 goto bad_fork_cleanup_fs;
1258 if ((retval = copy_signal(clone_flags, p)))
1259 goto bad_fork_cleanup_sighand;
1260 if ((retval = copy_mm(clone_flags, p)))
1261 goto bad_fork_cleanup_signal;
1262 if ((retval = copy_namespaces(clone_flags, p)))
1263 goto bad_fork_cleanup_mm;
1264 if ((retval = copy_io(clone_flags, p)))
1265 goto bad_fork_cleanup_namespaces;
1266 retval = copy_thread(clone_flags, stack_start, stack_size, p, regs);
1267 if (retval)
1268 goto bad_fork_cleanup_io;
1270 if (pid != &init_struct_pid) {
1271 retval = -ENOMEM;
1272 pid = alloc_pid(p->nsproxy->pid_ns);
1273 if (!pid)
1274 goto bad_fork_cleanup_io;
1277 p->pid = pid_nr(pid);
1278 p->tgid = p->pid;
1279 if (clone_flags & CLONE_THREAD)
1280 p->tgid = current->tgid;
1282 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1284 * Clear TID on mm_release()?
1286 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr: NULL;
1287 #ifdef CONFIG_BLOCK
1288 p->plug = NULL;
1289 #endif
1290 #ifdef CONFIG_FUTEX
1291 p->robust_list = NULL;
1292 #ifdef CONFIG_COMPAT
1293 p->compat_robust_list = NULL;
1294 #endif
1295 INIT_LIST_HEAD(&p->pi_state_list);
1296 p->pi_state_cache = NULL;
1297 #endif
1299 * sigaltstack should be cleared when sharing the same VM
1301 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1302 p->sas_ss_sp = p->sas_ss_size = 0;
1305 * Syscall tracing and stepping should be turned off in the
1306 * child regardless of CLONE_PTRACE.
1308 user_disable_single_step(p);
1309 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1310 #ifdef TIF_SYSCALL_EMU
1311 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1312 #endif
1313 clear_all_latency_tracing(p);
1315 /* ok, now we should be set up.. */
1316 p->exit_signal = (clone_flags & CLONE_THREAD) ? -1 : (clone_flags & CSIGNAL);
1317 p->pdeath_signal = 0;
1318 p->exit_state = 0;
1321 * Ok, make it visible to the rest of the system.
1322 * We dont wake it up yet.
1324 p->group_leader = p;
1325 INIT_LIST_HEAD(&p->thread_group);
1327 /* Now that the task is set up, run cgroup callbacks if
1328 * necessary. We need to run them before the task is visible
1329 * on the tasklist. */
1330 cgroup_fork_callbacks(p);
1331 cgroup_callbacks_done = 1;
1333 /* Need tasklist lock for parent etc handling! */
1334 write_lock_irq(&tasklist_lock);
1336 /* CLONE_PARENT re-uses the old parent */
1337 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1338 p->real_parent = current->real_parent;
1339 p->parent_exec_id = current->parent_exec_id;
1340 } else {
1341 p->real_parent = current;
1342 p->parent_exec_id = current->self_exec_id;
1345 spin_lock(&current->sighand->siglock);
1348 * Process group and session signals need to be delivered to just the
1349 * parent before the fork or both the parent and the child after the
1350 * fork. Restart if a signal comes in before we add the new process to
1351 * it's process group.
1352 * A fatal signal pending means that current will exit, so the new
1353 * thread can't slip out of an OOM kill (or normal SIGKILL).
1355 recalc_sigpending();
1356 if (signal_pending(current)) {
1357 spin_unlock(&current->sighand->siglock);
1358 write_unlock_irq(&tasklist_lock);
1359 retval = -ERESTARTNOINTR;
1360 goto bad_fork_free_pid;
1363 if (clone_flags & CLONE_THREAD) {
1364 current->signal->nr_threads++;
1365 atomic_inc(&current->signal->live);
1366 atomic_inc(&current->signal->sigcnt);
1367 p->group_leader = current->group_leader;
1368 list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group);
1371 if (likely(p->pid)) {
1372 tracehook_finish_clone(p, clone_flags, trace);
1374 if (thread_group_leader(p)) {
1375 if (is_child_reaper(pid))
1376 p->nsproxy->pid_ns->child_reaper = p;
1378 p->signal->leader_pid = pid;
1379 p->signal->tty = tty_kref_get(current->signal->tty);
1380 attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
1381 attach_pid(p, PIDTYPE_SID, task_session(current));
1382 list_add_tail(&p->sibling, &p->real_parent->children);
1383 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1384 __this_cpu_inc(process_counts);
1386 attach_pid(p, PIDTYPE_PID, pid);
1387 nr_threads++;
1390 total_forks++;
1391 spin_unlock(&current->sighand->siglock);
1392 write_unlock_irq(&tasklist_lock);
1393 proc_fork_connector(p);
1394 cgroup_post_fork(p);
1395 if (clone_flags & CLONE_THREAD)
1396 threadgroup_fork_read_unlock(current);
1397 perf_event_fork(p);
1398 return p;
1400 bad_fork_free_pid:
1401 if (pid != &init_struct_pid)
1402 free_pid(pid);
1403 bad_fork_cleanup_io:
1404 if (p->io_context)
1405 exit_io_context(p);
1406 bad_fork_cleanup_namespaces:
1407 exit_task_namespaces(p);
1408 bad_fork_cleanup_mm:
1409 if (p->mm) {
1410 task_lock(p);
1411 if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
1412 atomic_dec(&p->mm->oom_disable_count);
1413 task_unlock(p);
1414 mmput(p->mm);
1416 bad_fork_cleanup_signal:
1417 if (!(clone_flags & CLONE_THREAD))
1418 free_signal_struct(p->signal);
1419 bad_fork_cleanup_sighand:
1420 __cleanup_sighand(p->sighand);
1421 bad_fork_cleanup_fs:
1422 exit_fs(p); /* blocking */
1423 bad_fork_cleanup_files:
1424 exit_files(p); /* blocking */
1425 bad_fork_cleanup_semundo:
1426 exit_sem(p);
1427 bad_fork_cleanup_audit:
1428 audit_free(p);
1429 bad_fork_cleanup_policy:
1430 perf_event_free_task(p);
1431 #ifdef CONFIG_NUMA
1432 mpol_put(p->mempolicy);
1433 bad_fork_cleanup_cgroup:
1434 #endif
1435 if (clone_flags & CLONE_THREAD)
1436 threadgroup_fork_read_unlock(current);
1437 cgroup_exit(p, cgroup_callbacks_done);
1438 delayacct_tsk_free(p);
1439 module_put(task_thread_info(p)->exec_domain->module);
1440 bad_fork_cleanup_count:
1441 atomic_dec(&p->cred->user->processes);
1442 exit_creds(p);
1443 bad_fork_free:
1444 free_task(p);
1445 fork_out:
1446 return ERR_PTR(retval);
1449 noinline struct pt_regs * __cpuinit __attribute__((weak)) idle_regs(struct pt_regs *regs)
1451 memset(regs, 0, sizeof(struct pt_regs));
1452 return regs;
1455 static inline void init_idle_pids(struct pid_link *links)
1457 enum pid_type type;
1459 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1460 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1461 links[type].pid = &init_struct_pid;
1465 struct task_struct * __cpuinit fork_idle(int cpu)
1467 struct task_struct *task;
1468 struct pt_regs regs;
1470 task = copy_process(CLONE_VM, 0, idle_regs(&regs), 0, NULL,
1471 &init_struct_pid, 0);
1472 if (!IS_ERR(task)) {
1473 init_idle_pids(task->pids);
1474 init_idle(task, cpu);
1477 return task;
1481 * Ok, this is the main fork-routine.
1483 * It copies the process, and if successful kick-starts
1484 * it and waits for it to finish using the VM if required.
1486 long do_fork(unsigned long clone_flags,
1487 unsigned long stack_start,
1488 struct pt_regs *regs,
1489 unsigned long stack_size,
1490 int __user *parent_tidptr,
1491 int __user *child_tidptr)
1493 struct task_struct *p;
1494 int trace = 0;
1495 long nr;
1498 * Do some preliminary argument and permissions checking before we
1499 * actually start allocating stuff
1501 if (clone_flags & CLONE_NEWUSER) {
1502 if (clone_flags & CLONE_THREAD)
1503 return -EINVAL;
1504 /* hopefully this check will go away when userns support is
1505 * complete
1507 if (!capable(CAP_SYS_ADMIN) || !capable(CAP_SETUID) ||
1508 !capable(CAP_SETGID))
1509 return -EPERM;
1513 * When called from kernel_thread, don't do user tracing stuff.
1515 if (likely(user_mode(regs)))
1516 trace = tracehook_prepare_clone(clone_flags);
1518 p = copy_process(clone_flags, stack_start, regs, stack_size,
1519 child_tidptr, NULL, trace);
1521 * Do this prior waking up the new thread - the thread pointer
1522 * might get invalid after that point, if the thread exits quickly.
1524 if (!IS_ERR(p)) {
1525 struct completion vfork;
1527 trace_sched_process_fork(current, p);
1529 nr = task_pid_vnr(p);
1531 if (clone_flags & CLONE_PARENT_SETTID)
1532 put_user(nr, parent_tidptr);
1534 if (clone_flags & CLONE_VFORK) {
1535 p->vfork_done = &vfork;
1536 init_completion(&vfork);
1539 audit_finish_fork(p);
1540 tracehook_report_clone(regs, clone_flags, nr, p);
1543 * We set PF_STARTING at creation in case tracing wants to
1544 * use this to distinguish a fully live task from one that
1545 * hasn't gotten to tracehook_report_clone() yet. Now we
1546 * clear it and set the child going.
1548 p->flags &= ~PF_STARTING;
1550 wake_up_new_task(p);
1552 tracehook_report_clone_complete(trace, regs,
1553 clone_flags, nr, p);
1555 if (clone_flags & CLONE_VFORK) {
1556 freezer_do_not_count();
1557 wait_for_completion(&vfork);
1558 freezer_count();
1559 tracehook_report_vfork_done(p, nr);
1561 } else {
1562 nr = PTR_ERR(p);
1564 return nr;
1567 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1568 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1569 #endif
1571 static void sighand_ctor(void *data)
1573 struct sighand_struct *sighand = data;
1575 spin_lock_init(&sighand->siglock);
1576 init_waitqueue_head(&sighand->signalfd_wqh);
1579 void __init proc_caches_init(void)
1581 sighand_cachep = kmem_cache_create("sighand_cache",
1582 sizeof(struct sighand_struct), 0,
1583 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1584 SLAB_NOTRACK, sighand_ctor);
1585 signal_cachep = kmem_cache_create("signal_cache",
1586 sizeof(struct signal_struct), 0,
1587 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1588 files_cachep = kmem_cache_create("files_cache",
1589 sizeof(struct files_struct), 0,
1590 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1591 fs_cachep = kmem_cache_create("fs_cache",
1592 sizeof(struct fs_struct), 0,
1593 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1594 mm_cachep = kmem_cache_create("mm_struct",
1595 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1596 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1597 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1598 mmap_init();
1602 * Check constraints on flags passed to the unshare system call.
1604 static int check_unshare_flags(unsigned long unshare_flags)
1606 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1607 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1608 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET))
1609 return -EINVAL;
1611 * Not implemented, but pretend it works if there is nothing to
1612 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1613 * needs to unshare vm.
1615 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1616 /* FIXME: get_task_mm() increments ->mm_users */
1617 if (atomic_read(&current->mm->mm_users) > 1)
1618 return -EINVAL;
1621 return 0;
1625 * Unshare the filesystem structure if it is being shared
1627 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1629 struct fs_struct *fs = current->fs;
1631 if (!(unshare_flags & CLONE_FS) || !fs)
1632 return 0;
1634 /* don't need lock here; in the worst case we'll do useless copy */
1635 if (fs->users == 1)
1636 return 0;
1638 *new_fsp = copy_fs_struct(fs);
1639 if (!*new_fsp)
1640 return -ENOMEM;
1642 return 0;
1646 * Unshare file descriptor table if it is being shared
1648 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1650 struct files_struct *fd = current->files;
1651 int error = 0;
1653 if ((unshare_flags & CLONE_FILES) &&
1654 (fd && atomic_read(&fd->count) > 1)) {
1655 *new_fdp = dup_fd(fd, &error);
1656 if (!*new_fdp)
1657 return error;
1660 return 0;
1664 * unshare allows a process to 'unshare' part of the process
1665 * context which was originally shared using clone. copy_*
1666 * functions used by do_fork() cannot be used here directly
1667 * because they modify an inactive task_struct that is being
1668 * constructed. Here we are modifying the current, active,
1669 * task_struct.
1671 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1673 struct fs_struct *fs, *new_fs = NULL;
1674 struct files_struct *fd, *new_fd = NULL;
1675 struct nsproxy *new_nsproxy = NULL;
1676 int do_sysvsem = 0;
1677 int err;
1679 err = check_unshare_flags(unshare_flags);
1680 if (err)
1681 goto bad_unshare_out;
1684 * If unsharing namespace, must also unshare filesystem information.
1686 if (unshare_flags & CLONE_NEWNS)
1687 unshare_flags |= CLONE_FS;
1689 * CLONE_NEWIPC must also detach from the undolist: after switching
1690 * to a new ipc namespace, the semaphore arrays from the old
1691 * namespace are unreachable.
1693 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1694 do_sysvsem = 1;
1695 if ((err = unshare_fs(unshare_flags, &new_fs)))
1696 goto bad_unshare_out;
1697 if ((err = unshare_fd(unshare_flags, &new_fd)))
1698 goto bad_unshare_cleanup_fs;
1699 if ((err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
1700 new_fs)))
1701 goto bad_unshare_cleanup_fd;
1703 if (new_fs || new_fd || do_sysvsem || new_nsproxy) {
1704 if (do_sysvsem) {
1706 * CLONE_SYSVSEM is equivalent to sys_exit().
1708 exit_sem(current);
1711 if (new_nsproxy) {
1712 switch_task_namespaces(current, new_nsproxy);
1713 new_nsproxy = NULL;
1716 task_lock(current);
1718 if (new_fs) {
1719 fs = current->fs;
1720 spin_lock(&fs->lock);
1721 current->fs = new_fs;
1722 if (--fs->users)
1723 new_fs = NULL;
1724 else
1725 new_fs = fs;
1726 spin_unlock(&fs->lock);
1729 if (new_fd) {
1730 fd = current->files;
1731 current->files = new_fd;
1732 new_fd = fd;
1735 task_unlock(current);
1738 if (new_nsproxy)
1739 put_nsproxy(new_nsproxy);
1741 bad_unshare_cleanup_fd:
1742 if (new_fd)
1743 put_files_struct(new_fd);
1745 bad_unshare_cleanup_fs:
1746 if (new_fs)
1747 free_fs_struct(new_fs);
1749 bad_unshare_out:
1750 return err;
1754 * Helper to unshare the files of the current task.
1755 * We don't want to expose copy_files internals to
1756 * the exec layer of the kernel.
1759 int unshare_files(struct files_struct **displaced)
1761 struct task_struct *task = current;
1762 struct files_struct *copy = NULL;
1763 int error;
1765 error = unshare_fd(CLONE_FILES, &copy);
1766 if (error || !copy) {
1767 *displaced = NULL;
1768 return error;
1770 *displaced = task->files;
1771 task_lock(task);
1772 task->files = copy;
1773 task_unlock(task);
1774 return 0;