projects / deliverable / linux.git / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
thermal: cpu_cooling: fix typo highjack -> hijack
[deliverable/linux.git] / kernel / fork.c
1 /*
2 * linux/kernel/fork.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
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()'
12 */
13
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/mm.h>
32 #include <linux/vmacache.h>
33 #include <linux/nsproxy.h>
34 #include <linux/capability.h>
35 #include <linux/cpu.h>
36 #include <linux/cgroup.h>
37 #include <linux/security.h>
38 #include <linux/hugetlb.h>
39 #include <linux/seccomp.h>
40 #include <linux/swap.h>
41 #include <linux/syscalls.h>
42 #include <linux/jiffies.h>
43 #include <linux/futex.h>
44 #include <linux/compat.h>
45 #include <linux/kthread.h>
46 #include <linux/task_io_accounting_ops.h>
47 #include <linux/rcupdate.h>
48 #include <linux/ptrace.h>
49 #include <linux/mount.h>
50 #include <linux/audit.h>
51 #include <linux/memcontrol.h>
52 #include <linux/ftrace.h>
53 #include <linux/proc_fs.h>
54 #include <linux/profile.h>
55 #include <linux/rmap.h>
56 #include <linux/ksm.h>
57 #include <linux/acct.h>
58 #include <linux/tsacct_kern.h>
59 #include <linux/cn_proc.h>
60 #include <linux/freezer.h>
61 #include <linux/delayacct.h>
62 #include <linux/taskstats_kern.h>
63 #include <linux/random.h>
64 #include <linux/tty.h>
65 #include <linux/blkdev.h>
66 #include <linux/fs_struct.h>
67 #include <linux/magic.h>
68 #include <linux/perf_event.h>
69 #include <linux/posix-timers.h>
70 #include <linux/user-return-notifier.h>
71 #include <linux/oom.h>
72 #include <linux/khugepaged.h>
73 #include <linux/signalfd.h>
74 #include <linux/uprobes.h>
75 #include <linux/aio.h>
76 #include <linux/compiler.h>
77
78 #include <asm/pgtable.h>
79 #include <asm/pgalloc.h>
80 #include <asm/uaccess.h>
81 #include <asm/mmu_context.h>
82 #include <asm/cacheflush.h>
83 #include <asm/tlbflush.h>
84
85 #include <trace/events/sched.h>
86
87 #define CREATE_TRACE_POINTS
88 #include <trace/events/task.h>
89
90 /*
91 * Protected counters by write_lock_irq(&tasklist_lock)
92 */
93 unsigned long total_forks; /* Handle normal Linux uptimes. */
94 int nr_threads; /* The idle threads do not count.. */
95
96 int max_threads; /* tunable limit on nr_threads */
97
98 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
99
100 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
101
102 #ifdef CONFIG_PROVE_RCU
103 int lockdep_tasklist_lock_is_held(void)
104 {
105 return lockdep_is_held(&tasklist_lock);
106 }
107 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
108 #endif /* #ifdef CONFIG_PROVE_RCU */
109
110 int nr_processes(void)
111 {
112 int cpu;
113 int total = 0;
114
115 for_each_possible_cpu(cpu)
116 total += per_cpu(process_counts, cpu);
117
118 return total;
119 }
120
121 void __weak arch_release_task_struct(struct task_struct *tsk)
122 {
123 }
124
125 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
126 static struct kmem_cache *task_struct_cachep;
127
128 static inline struct task_struct *alloc_task_struct_node(int node)
129 {
130 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
131 }
132
133 static inline void free_task_struct(struct task_struct *tsk)
134 {
135 kmem_cache_free(task_struct_cachep, tsk);
136 }
137 #endif
138
139 void __weak arch_release_thread_info(struct thread_info *ti)
140 {
141 }
142
143 #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR
144
145 /*
146 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
147 * kmemcache based allocator.
148 */
149 # if THREAD_SIZE >= PAGE_SIZE
150 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
151 int node)
152 {
153 struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP,
154 THREAD_SIZE_ORDER);
155
156 return page ? page_address(page) : NULL;
157 }
158
159 static inline void free_thread_info(struct thread_info *ti)
160 {
161 free_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER);
162 }
163 # else
164 static struct kmem_cache *thread_info_cache;
165
166 static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
167 int node)
168 {
169 return kmem_cache_alloc_node(thread_info_cache, THREADINFO_GFP, node);
170 }
171
172 static void free_thread_info(struct thread_info *ti)
173 {
174 kmem_cache_free(thread_info_cache, ti);
175 }
176
177 void thread_info_cache_init(void)
178 {
179 thread_info_cache = kmem_cache_create("thread_info", THREAD_SIZE,
180 THREAD_SIZE, 0, NULL);
181 BUG_ON(thread_info_cache == NULL);
182 }
183 # endif
184 #endif
185
186 /* SLAB cache for signal_struct structures (tsk->signal) */
187 static struct kmem_cache *signal_cachep;
188
189 /* SLAB cache for sighand_struct structures (tsk->sighand) */
190 struct kmem_cache *sighand_cachep;
191
192 /* SLAB cache for files_struct structures (tsk->files) */
193 struct kmem_cache *files_cachep;
194
195 /* SLAB cache for fs_struct structures (tsk->fs) */
196 struct kmem_cache *fs_cachep;
197
198 /* SLAB cache for vm_area_struct structures */
199 struct kmem_cache *vm_area_cachep;
200
201 /* SLAB cache for mm_struct structures (tsk->mm) */
202 static struct kmem_cache *mm_cachep;
203
204 static void account_kernel_stack(struct thread_info *ti, int account)
205 {
206 struct zone *zone = page_zone(virt_to_page(ti));
207
208 mod_zone_page_state(zone, NR_KERNEL_STACK, account);
209 }
210
211 void free_task(struct task_struct *tsk)
212 {
213 account_kernel_stack(tsk->stack, -1);
214 arch_release_thread_info(tsk->stack);
215 free_thread_info(tsk->stack);
216 rt_mutex_debug_task_free(tsk);
217 ftrace_graph_exit_task(tsk);
218 put_seccomp_filter(tsk);
219 arch_release_task_struct(tsk);
220 free_task_struct(tsk);
221 }
222 EXPORT_SYMBOL(free_task);
223
224 static inline void free_signal_struct(struct signal_struct *sig)
225 {
226 taskstats_tgid_free(sig);
227 sched_autogroup_exit(sig);
228 kmem_cache_free(signal_cachep, sig);
229 }
230
231 static inline void put_signal_struct(struct signal_struct *sig)
232 {
233 if (atomic_dec_and_test(&sig->sigcnt))
234 free_signal_struct(sig);
235 }
236
237 void __put_task_struct(struct task_struct *tsk)
238 {
239 WARN_ON(!tsk->exit_state);
240 WARN_ON(atomic_read(&tsk->usage));
241 WARN_ON(tsk == current);
242
243 task_numa_free(tsk);
244 security_task_free(tsk);
245 exit_creds(tsk);
246 delayacct_tsk_free(tsk);
247 put_signal_struct(tsk->signal);
248
249 if (!profile_handoff_task(tsk))
250 free_task(tsk);
251 }
252 EXPORT_SYMBOL_GPL(__put_task_struct);
253
254 void __init __weak arch_task_cache_init(void) { }
255
256 void __init fork_init(unsigned long mempages)
257 {
258 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
259 #ifndef ARCH_MIN_TASKALIGN
260 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
261 #endif
262 /* create a slab on which task_structs can be allocated */
263 task_struct_cachep =
264 kmem_cache_create("task_struct", sizeof(struct task_struct),
265 ARCH_MIN_TASKALIGN, SLAB_PANIC | SLAB_NOTRACK, NULL);
266 #endif
267
268 /* do the arch specific task caches init */
269 arch_task_cache_init();
270
271 /*
272 * The default maximum number of threads is set to a safe
273 * value: the thread structures can take up at most half
274 * of memory.
275 */
276 max_threads = mempages / (8 * THREAD_SIZE / PAGE_SIZE);
277
278 /*
279 * we need to allow at least 20 threads to boot a system
280 */
281 if (max_threads < 20)
282 max_threads = 20;
283
284 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
285 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
286 init_task.signal->rlim[RLIMIT_SIGPENDING] =
287 init_task.signal->rlim[RLIMIT_NPROC];
288 }
289
290 int __weak arch_dup_task_struct(struct task_struct *dst,
291 struct task_struct *src)
292 {
293 *dst = *src;
294 return 0;
295 }
296
297 static struct task_struct *dup_task_struct(struct task_struct *orig)
298 {
299 struct task_struct *tsk;
300 struct thread_info *ti;
301 unsigned long *stackend;
302 int node = tsk_fork_get_node(orig);
303 int err;
304
305 tsk = alloc_task_struct_node(node);
306 if (!tsk)
307 return NULL;
308
309 ti = alloc_thread_info_node(tsk, node);
310 if (!ti)
311 goto free_tsk;
312
313 err = arch_dup_task_struct(tsk, orig);
314 if (err)
315 goto free_ti;
316
317 tsk->stack = ti;
318
319 setup_thread_stack(tsk, orig);
320 clear_user_return_notifier(tsk);
321 clear_tsk_need_resched(tsk);
322 stackend = end_of_stack(tsk);
323 *stackend = STACK_END_MAGIC; /* for overflow detection */
324
325 #ifdef CONFIG_CC_STACKPROTECTOR
326 tsk->stack_canary = get_random_int();
327 #endif
328
329 /*
330 * One for us, one for whoever does the "release_task()" (usually
331 * parent)
332 */
333 atomic_set(&tsk->usage, 2);
334 #ifdef CONFIG_BLK_DEV_IO_TRACE
335 tsk->btrace_seq = 0;
336 #endif
337 tsk->splice_pipe = NULL;
338 tsk->task_frag.page = NULL;
339
340 account_kernel_stack(ti, 1);
341
342 return tsk;
343
344 free_ti:
345 free_thread_info(ti);
346 free_tsk:
347 free_task_struct(tsk);
348 return NULL;
349 }
350
351 #ifdef CONFIG_MMU
352 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
353 {
354 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
355 struct rb_node **rb_link, *rb_parent;
356 int retval;
357 unsigned long charge;
358
359 uprobe_start_dup_mmap();
360 down_write(&oldmm->mmap_sem);
361 flush_cache_dup_mm(oldmm);
362 uprobe_dup_mmap(oldmm, mm);
363 /*
364 * Not linked in yet - no deadlock potential:
365 */
366 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
367
368 mm->locked_vm = 0;
369 mm->mmap = NULL;
370 mm->vmacache_seqnum = 0;
371 mm->map_count = 0;
372 cpumask_clear(mm_cpumask(mm));
373 mm->mm_rb = RB_ROOT;
374 rb_link = &mm->mm_rb.rb_node;
375 rb_parent = NULL;
376 pprev = &mm->mmap;
377 retval = ksm_fork(mm, oldmm);
378 if (retval)
379 goto out;
380 retval = khugepaged_fork(mm, oldmm);
381 if (retval)
382 goto out;
383
384 prev = NULL;
385 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
386 struct file *file;
387
388 if (mpnt->vm_flags & VM_DONTCOPY) {
389 vm_stat_account(mm, mpnt->vm_flags, mpnt->vm_file,
390 -vma_pages(mpnt));
391 continue;
392 }
393 charge = 0;
394 if (mpnt->vm_flags & VM_ACCOUNT) {
395 unsigned long len = vma_pages(mpnt);
396
397 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
398 goto fail_nomem;
399 charge = len;
400 }
401 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
402 if (!tmp)
403 goto fail_nomem;
404 *tmp = *mpnt;
405 INIT_LIST_HEAD(&tmp->anon_vma_chain);
406 retval = vma_dup_policy(mpnt, tmp);
407 if (retval)
408 goto fail_nomem_policy;
409 tmp->vm_mm = mm;
410 if (anon_vma_fork(tmp, mpnt))
411 goto fail_nomem_anon_vma_fork;
412 tmp->vm_flags &= ~VM_LOCKED;
413 tmp->vm_next = tmp->vm_prev = NULL;
414 file = tmp->vm_file;
415 if (file) {
416 struct inode *inode = file_inode(file);
417 struct address_space *mapping = file->f_mapping;
418
419 get_file(file);
420 if (tmp->vm_flags & VM_DENYWRITE)
421 atomic_dec(&inode->i_writecount);
422 mutex_lock(&mapping->i_mmap_mutex);
423 if (tmp->vm_flags & VM_SHARED)
424 mapping->i_mmap_writable++;
425 flush_dcache_mmap_lock(mapping);
426 /* insert tmp into the share list, just after mpnt */
427 if (unlikely(tmp->vm_flags & VM_NONLINEAR))
428 vma_nonlinear_insert(tmp,
429 &mapping->i_mmap_nonlinear);
430 else
431 vma_interval_tree_insert_after(tmp, mpnt,
432 &mapping->i_mmap);
433 flush_dcache_mmap_unlock(mapping);
434 mutex_unlock(&mapping->i_mmap_mutex);
435 }
436
437 /*
438 * Clear hugetlb-related page reserves for children. This only
439 * affects MAP_PRIVATE mappings. Faults generated by the child
440 * are not guaranteed to succeed, even if read-only
441 */
442 if (is_vm_hugetlb_page(tmp))
443 reset_vma_resv_huge_pages(tmp);
444
445 /*
446 * Link in the new vma and copy the page table entries.
447 */
448 *pprev = tmp;
449 pprev = &tmp->vm_next;
450 tmp->vm_prev = prev;
451 prev = tmp;
452
453 __vma_link_rb(mm, tmp, rb_link, rb_parent);
454 rb_link = &tmp->vm_rb.rb_right;
455 rb_parent = &tmp->vm_rb;
456
457 mm->map_count++;
458 retval = copy_page_range(mm, oldmm, mpnt);
459
460 if (tmp->vm_ops && tmp->vm_ops->open)
461 tmp->vm_ops->open(tmp);
462
463 if (retval)
464 goto out;
465 }
466 /* a new mm has just been created */
467 arch_dup_mmap(oldmm, mm);
468 retval = 0;
469 out:
470 up_write(&mm->mmap_sem);
471 flush_tlb_mm(oldmm);
472 up_write(&oldmm->mmap_sem);
473 uprobe_end_dup_mmap();
474 return retval;
475 fail_nomem_anon_vma_fork:
476 mpol_put(vma_policy(tmp));
477 fail_nomem_policy:
478 kmem_cache_free(vm_area_cachep, tmp);
479 fail_nomem:
480 retval = -ENOMEM;
481 vm_unacct_memory(charge);
482 goto out;
483 }
484
485 static inline int mm_alloc_pgd(struct mm_struct *mm)
486 {
487 mm->pgd = pgd_alloc(mm);
488 if (unlikely(!mm->pgd))
489 return -ENOMEM;
490 return 0;
491 }
492
493 static inline void mm_free_pgd(struct mm_struct *mm)
494 {
495 pgd_free(mm, mm->pgd);
496 }
497 #else
498 #define dup_mmap(mm, oldmm) (0)
499 #define mm_alloc_pgd(mm) (0)
500 #define mm_free_pgd(mm)
501 #endif /* CONFIG_MMU */
502
503 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
504
505 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
506 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
507
508 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
509
510 static int __init coredump_filter_setup(char *s)
511 {
512 default_dump_filter =
513 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
514 MMF_DUMP_FILTER_MASK;
515 return 1;
516 }
517
518 __setup("coredump_filter=", coredump_filter_setup);
519
520 #include <linux/init_task.h>
521
522 static void mm_init_aio(struct mm_struct *mm)
523 {
524 #ifdef CONFIG_AIO
525 spin_lock_init(&mm->ioctx_lock);
526 mm->ioctx_table = NULL;
527 #endif
528 }
529
530 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
531 {
532 atomic_set(&mm->mm_users, 1);
533 atomic_set(&mm->mm_count, 1);
534 init_rwsem(&mm->mmap_sem);
535 INIT_LIST_HEAD(&mm->mmlist);
536 mm->core_state = NULL;
537 atomic_long_set(&mm->nr_ptes, 0);
538 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
539 spin_lock_init(&mm->page_table_lock);
540 mm_init_aio(mm);
541 mm_init_owner(mm, p);
542 clear_tlb_flush_pending(mm);
543
544 if (current->mm) {
545 mm->flags = current->mm->flags & MMF_INIT_MASK;
546 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
547 } else {
548 mm->flags = default_dump_filter;
549 mm->def_flags = 0;
550 }
551
552 if (likely(!mm_alloc_pgd(mm))) {
553 mmu_notifier_mm_init(mm);
554 return mm;
555 }
556
557 free_mm(mm);
558 return NULL;
559 }
560
561 static void check_mm(struct mm_struct *mm)
562 {
563 int i;
564
565 for (i = 0; i < NR_MM_COUNTERS; i++) {
566 long x = atomic_long_read(&mm->rss_stat.count[i]);
567
568 if (unlikely(x))
569 printk(KERN_ALERT "BUG: Bad rss-counter state "
570 "mm:%p idx:%d val:%ld\n", mm, i, x);
571 }
572
573 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
574 VM_BUG_ON(mm->pmd_huge_pte);
575 #endif
576 }
577
578 /*
579 * Allocate and initialize an mm_struct.
580 */
581 struct mm_struct *mm_alloc(void)
582 {
583 struct mm_struct *mm;
584
585 mm = allocate_mm();
586 if (!mm)
587 return NULL;
588
589 memset(mm, 0, sizeof(*mm));
590 mm_init_cpumask(mm);
591 return mm_init(mm, current);
592 }
593
594 /*
595 * Called when the last reference to the mm
596 * is dropped: either by a lazy thread or by
597 * mmput. Free the page directory and the mm.
598 */
599 void __mmdrop(struct mm_struct *mm)
600 {
601 BUG_ON(mm == &init_mm);
602 mm_free_pgd(mm);
603 destroy_context(mm);
604 mmu_notifier_mm_destroy(mm);
605 check_mm(mm);
606 free_mm(mm);
607 }
608 EXPORT_SYMBOL_GPL(__mmdrop);
609
610 /*
611 * Decrement the use count and release all resources for an mm.
612 */
613 void mmput(struct mm_struct *mm)
614 {
615 might_sleep();
616
617 if (atomic_dec_and_test(&mm->mm_users)) {
618 uprobe_clear_state(mm);
619 exit_aio(mm);
620 ksm_exit(mm);
621 khugepaged_exit(mm); /* must run before exit_mmap */
622 exit_mmap(mm);
623 set_mm_exe_file(mm, NULL);
624 if (!list_empty(&mm->mmlist)) {
625 spin_lock(&mmlist_lock);
626 list_del(&mm->mmlist);
627 spin_unlock(&mmlist_lock);
628 }
629 if (mm->binfmt)
630 module_put(mm->binfmt->module);
631 mmdrop(mm);
632 }
633 }
634 EXPORT_SYMBOL_GPL(mmput);
635
636 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
637 {
638 if (new_exe_file)
639 get_file(new_exe_file);
640 if (mm->exe_file)
641 fput(mm->exe_file);
642 mm->exe_file = new_exe_file;
643 }
644
645 struct file *get_mm_exe_file(struct mm_struct *mm)
646 {
647 struct file *exe_file;
648
649 /* We need mmap_sem to protect against races with removal of exe_file */
650 down_read(&mm->mmap_sem);
651 exe_file = mm->exe_file;
652 if (exe_file)
653 get_file(exe_file);
654 up_read(&mm->mmap_sem);
655 return exe_file;
656 }
657
658 static void dup_mm_exe_file(struct mm_struct *oldmm, struct mm_struct *newmm)
659 {
660 /* It's safe to write the exe_file pointer without exe_file_lock because
661 * this is called during fork when the task is not yet in /proc */
662 newmm->exe_file = get_mm_exe_file(oldmm);
663 }
664
665 /**
666 * get_task_mm - acquire a reference to the task's mm
667 *
668 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
669 * this kernel workthread has transiently adopted a user mm with use_mm,
670 * to do its AIO) is not set and if so returns a reference to it, after
671 * bumping up the use count. User must release the mm via mmput()
672 * after use. Typically used by /proc and ptrace.
673 */
674 struct mm_struct *get_task_mm(struct task_struct *task)
675 {
676 struct mm_struct *mm;
677
678 task_lock(task);
679 mm = task->mm;
680 if (mm) {
681 if (task->flags & PF_KTHREAD)
682 mm = NULL;
683 else
684 atomic_inc(&mm->mm_users);
685 }
686 task_unlock(task);
687 return mm;
688 }
689 EXPORT_SYMBOL_GPL(get_task_mm);
690
691 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
692 {
693 struct mm_struct *mm;
694 int err;
695
696 err = mutex_lock_killable(&task->signal->cred_guard_mutex);
697 if (err)
698 return ERR_PTR(err);
699
700 mm = get_task_mm(task);
701 if (mm && mm != current->mm &&
702 !ptrace_may_access(task, mode)) {
703 mmput(mm);
704 mm = ERR_PTR(-EACCES);
705 }
706 mutex_unlock(&task->signal->cred_guard_mutex);
707
708 return mm;
709 }
710
711 static void complete_vfork_done(struct task_struct *tsk)
712 {
713 struct completion *vfork;
714
715 task_lock(tsk);
716 vfork = tsk->vfork_done;
717 if (likely(vfork)) {
718 tsk->vfork_done = NULL;
719 complete(vfork);
720 }
721 task_unlock(tsk);
722 }
723
724 static int wait_for_vfork_done(struct task_struct *child,
725 struct completion *vfork)
726 {
727 int killed;
728
729 freezer_do_not_count();
730 killed = wait_for_completion_killable(vfork);
731 freezer_count();
732
733 if (killed) {
734 task_lock(child);
735 child->vfork_done = NULL;
736 task_unlock(child);
737 }
738
739 put_task_struct(child);
740 return killed;
741 }
742
743 /* Please note the differences between mmput and mm_release.
744 * mmput is called whenever we stop holding onto a mm_struct,
745 * error success whatever.
746 *
747 * mm_release is called after a mm_struct has been removed
748 * from the current process.
749 *
750 * This difference is important for error handling, when we
751 * only half set up a mm_struct for a new process and need to restore
752 * the old one. Because we mmput the new mm_struct before
753 * restoring the old one. . .
754 * Eric Biederman 10 January 1998
755 */
756 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
757 {
758 /* Get rid of any futexes when releasing the mm */
759 #ifdef CONFIG_FUTEX
760 if (unlikely(tsk->robust_list)) {
761 exit_robust_list(tsk);
762 tsk->robust_list = NULL;
763 }
764 #ifdef CONFIG_COMPAT
765 if (unlikely(tsk->compat_robust_list)) {
766 compat_exit_robust_list(tsk);
767 tsk->compat_robust_list = NULL;
768 }
769 #endif
770 if (unlikely(!list_empty(&tsk->pi_state_list)))
771 exit_pi_state_list(tsk);
772 #endif
773
774 uprobe_free_utask(tsk);
775
776 /* Get rid of any cached register state */
777 deactivate_mm(tsk, mm);
778
779 /*
780 * If we're exiting normally, clear a user-space tid field if
781 * requested. We leave this alone when dying by signal, to leave
782 * the value intact in a core dump, and to save the unnecessary
783 * trouble, say, a killed vfork parent shouldn't touch this mm.
784 * Userland only wants this done for a sys_exit.
785 */
786 if (tsk->clear_child_tid) {
787 if (!(tsk->flags & PF_SIGNALED) &&
788 atomic_read(&mm->mm_users) > 1) {
789 /*
790 * We don't check the error code - if userspace has
791 * not set up a proper pointer then tough luck.
792 */
793 put_user(0, tsk->clear_child_tid);
794 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
795 1, NULL, NULL, 0);
796 }
797 tsk->clear_child_tid = NULL;
798 }
799
800 /*
801 * All done, finally we can wake up parent and return this mm to him.
802 * Also kthread_stop() uses this completion for synchronization.
803 */
804 if (tsk->vfork_done)
805 complete_vfork_done(tsk);
806 }
807
808 /*
809 * Allocate a new mm structure and copy contents from the
810 * mm structure of the passed in task structure.
811 */
812 static struct mm_struct *dup_mm(struct task_struct *tsk)
813 {
814 struct mm_struct *mm, *oldmm = current->mm;
815 int err;
816
817 mm = allocate_mm();
818 if (!mm)
819 goto fail_nomem;
820
821 memcpy(mm, oldmm, sizeof(*mm));
822 mm_init_cpumask(mm);
823
824 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
825 mm->pmd_huge_pte = NULL;
826 #endif
827 if (!mm_init(mm, tsk))
828 goto fail_nomem;
829
830 if (init_new_context(tsk, mm))
831 goto fail_nocontext;
832
833 dup_mm_exe_file(oldmm, mm);
834
835 err = dup_mmap(mm, oldmm);
836 if (err)
837 goto free_pt;
838
839 mm->hiwater_rss = get_mm_rss(mm);
840 mm->hiwater_vm = mm->total_vm;
841
842 if (mm->binfmt && !try_module_get(mm->binfmt->module))
843 goto free_pt;
844
845 return mm;
846
847 free_pt:
848 /* don't put binfmt in mmput, we haven't got module yet */
849 mm->binfmt = NULL;
850 mmput(mm);
851
852 fail_nomem:
853 return NULL;
854
855 fail_nocontext:
856 /*
857 * If init_new_context() failed, we cannot use mmput() to free the mm
858 * because it calls destroy_context()
859 */
860 mm_free_pgd(mm);
861 free_mm(mm);
862 return NULL;
863 }
864
865 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
866 {
867 struct mm_struct *mm, *oldmm;
868 int retval;
869
870 tsk->min_flt = tsk->maj_flt = 0;
871 tsk->nvcsw = tsk->nivcsw = 0;
872 #ifdef CONFIG_DETECT_HUNG_TASK
873 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
874 #endif
875
876 tsk->mm = NULL;
877 tsk->active_mm = NULL;
878
879 /*
880 * Are we cloning a kernel thread?
881 *
882 * We need to steal a active VM for that..
883 */
884 oldmm = current->mm;
885 if (!oldmm)
886 return 0;
887
888 /* initialize the new vmacache entries */
889 vmacache_flush(tsk);
890
891 if (clone_flags & CLONE_VM) {
892 atomic_inc(&oldmm->mm_users);
893 mm = oldmm;
894 goto good_mm;
895 }
896
897 retval = -ENOMEM;
898 mm = dup_mm(tsk);
899 if (!mm)
900 goto fail_nomem;
901
902 good_mm:
903 tsk->mm = mm;
904 tsk->active_mm = mm;
905 return 0;
906
907 fail_nomem:
908 return retval;
909 }
910
911 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
912 {
913 struct fs_struct *fs = current->fs;
914 if (clone_flags & CLONE_FS) {
915 /* tsk->fs is already what we want */
916 spin_lock(&fs->lock);
917 if (fs->in_exec) {
918 spin_unlock(&fs->lock);
919 return -EAGAIN;
920 }
921 fs->users++;
922 spin_unlock(&fs->lock);
923 return 0;
924 }
925 tsk->fs = copy_fs_struct(fs);
926 if (!tsk->fs)
927 return -ENOMEM;
928 return 0;
929 }
930
931 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
932 {
933 struct files_struct *oldf, *newf;
934 int error = 0;
935
936 /*
937 * A background process may not have any files ...
938 */
939 oldf = current->files;
940 if (!oldf)
941 goto out;
942
943 if (clone_flags & CLONE_FILES) {
944 atomic_inc(&oldf->count);
945 goto out;
946 }
947
948 newf = dup_fd(oldf, &error);
949 if (!newf)
950 goto out;
951
952 tsk->files = newf;
953 error = 0;
954 out:
955 return error;
956 }
957
958 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
959 {
960 #ifdef CONFIG_BLOCK
961 struct io_context *ioc = current->io_context;
962 struct io_context *new_ioc;
963
964 if (!ioc)
965 return 0;
966 /*
967 * Share io context with parent, if CLONE_IO is set
968 */
969 if (clone_flags & CLONE_IO) {
970 ioc_task_link(ioc);
971 tsk->io_context = ioc;
972 } else if (ioprio_valid(ioc->ioprio)) {
973 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
974 if (unlikely(!new_ioc))
975 return -ENOMEM;
976
977 new_ioc->ioprio = ioc->ioprio;
978 put_io_context(new_ioc);
979 }
980 #endif
981 return 0;
982 }
983
984 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
985 {
986 struct sighand_struct *sig;
987
988 if (clone_flags & CLONE_SIGHAND) {
989 atomic_inc(&current->sighand->count);
990 return 0;
991 }
992 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
993 rcu_assign_pointer(tsk->sighand, sig);
994 if (!sig)
995 return -ENOMEM;
996 atomic_set(&sig->count, 1);
997 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
998 return 0;
999 }
1000
1001 void __cleanup_sighand(struct sighand_struct *sighand)
1002 {
1003 if (atomic_dec_and_test(&sighand->count)) {
1004 signalfd_cleanup(sighand);
1005 kmem_cache_free(sighand_cachep, sighand);
1006 }
1007 }
1008
1009
1010 /*
1011 * Initialize POSIX timer handling for a thread group.
1012 */
1013 static void posix_cpu_timers_init_group(struct signal_struct *sig)
1014 {
1015 unsigned long cpu_limit;
1016
1017 /* Thread group counters. */
1018 thread_group_cputime_init(sig);
1019
1020 cpu_limit = ACCESS_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1021 if (cpu_limit != RLIM_INFINITY) {
1022 sig->cputime_expires.prof_exp = secs_to_cputime(cpu_limit);
1023 sig->cputimer.running = 1;
1024 }
1025
1026 /* The timer lists. */
1027 INIT_LIST_HEAD(&sig->cpu_timers[0]);
1028 INIT_LIST_HEAD(&sig->cpu_timers[1]);
1029 INIT_LIST_HEAD(&sig->cpu_timers[2]);
1030 }
1031
1032 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1033 {
1034 struct signal_struct *sig;
1035
1036 if (clone_flags & CLONE_THREAD)
1037 return 0;
1038
1039 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1040 tsk->signal = sig;
1041 if (!sig)
1042 return -ENOMEM;
1043
1044 sig->nr_threads = 1;
1045 atomic_set(&sig->live, 1);
1046 atomic_set(&sig->sigcnt, 1);
1047
1048 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1049 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1050 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1051
1052 init_waitqueue_head(&sig->wait_chldexit);
1053 sig->curr_target = tsk;
1054 init_sigpending(&sig->shared_pending);
1055 INIT_LIST_HEAD(&sig->posix_timers);
1056
1057 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1058 sig->real_timer.function = it_real_fn;
1059
1060 task_lock(current->group_leader);
1061 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1062 task_unlock(current->group_leader);
1063
1064 posix_cpu_timers_init_group(sig);
1065
1066 tty_audit_fork(sig);
1067 sched_autogroup_fork(sig);
1068
1069 #ifdef CONFIG_CGROUPS
1070 init_rwsem(&sig->group_rwsem);
1071 #endif
1072
1073 sig->oom_score_adj = current->signal->oom_score_adj;
1074 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1075
1076 sig->has_child_subreaper = current->signal->has_child_subreaper ||
1077 current->signal->is_child_subreaper;
1078
1079 mutex_init(&sig->cred_guard_mutex);
1080
1081 return 0;
1082 }
1083
1084 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1085 {
1086 current->clear_child_tid = tidptr;
1087
1088 return task_pid_vnr(current);
1089 }
1090
1091 static void rt_mutex_init_task(struct task_struct *p)
1092 {
1093 raw_spin_lock_init(&p->pi_lock);
1094 #ifdef CONFIG_RT_MUTEXES
1095 p->pi_waiters = RB_ROOT;
1096 p->pi_waiters_leftmost = NULL;
1097 p->pi_blocked_on = NULL;
1098 p->pi_top_task = NULL;
1099 #endif
1100 }
1101
1102 #ifdef CONFIG_MEMCG
1103 void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1104 {
1105 mm->owner = p;
1106 }
1107 #endif /* CONFIG_MEMCG */
1108
1109 /*
1110 * Initialize POSIX timer handling for a single task.
1111 */
1112 static void posix_cpu_timers_init(struct task_struct *tsk)
1113 {
1114 tsk->cputime_expires.prof_exp = 0;
1115 tsk->cputime_expires.virt_exp = 0;
1116 tsk->cputime_expires.sched_exp = 0;
1117 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1118 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1119 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1120 }
1121
1122 static inline void
1123 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1124 {
1125 task->pids[type].pid = pid;
1126 }
1127
1128 /*
1129 * This creates a new process as a copy of the old one,
1130 * but does not actually start it yet.
1131 *
1132 * It copies the registers, and all the appropriate
1133 * parts of the process environment (as per the clone
1134 * flags). The actual kick-off is left to the caller.
1135 */
1136 static struct task_struct *copy_process(unsigned long clone_flags,
1137 unsigned long stack_start,
1138 unsigned long stack_size,
1139 int __user *child_tidptr,
1140 struct pid *pid,
1141 int trace)
1142 {
1143 int retval;
1144 struct task_struct *p;
1145
1146 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1147 return ERR_PTR(-EINVAL);
1148
1149 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1150 return ERR_PTR(-EINVAL);
1151
1152 /*
1153 * Thread groups must share signals as well, and detached threads
1154 * can only be started up within the thread group.
1155 */
1156 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1157 return ERR_PTR(-EINVAL);
1158
1159 /*
1160 * Shared signal handlers imply shared VM. By way of the above,
1161 * thread groups also imply shared VM. Blocking this case allows
1162 * for various simplifications in other code.
1163 */
1164 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1165 return ERR_PTR(-EINVAL);
1166
1167 /*
1168 * Siblings of global init remain as zombies on exit since they are
1169 * not reaped by their parent (swapper). To solve this and to avoid
1170 * multi-rooted process trees, prevent global and container-inits
1171 * from creating siblings.
1172 */
1173 if ((clone_flags & CLONE_PARENT) &&
1174 current->signal->flags & SIGNAL_UNKILLABLE)
1175 return ERR_PTR(-EINVAL);
1176
1177 /*
1178 * If the new process will be in a different pid or user namespace
1179 * do not allow it to share a thread group or signal handlers or
1180 * parent with the forking task.
1181 */
1182 if (clone_flags & CLONE_SIGHAND) {
1183 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
1184 (task_active_pid_ns(current) !=
1185 current->nsproxy->pid_ns_for_children))
1186 return ERR_PTR(-EINVAL);
1187 }
1188
1189 retval = security_task_create(clone_flags);
1190 if (retval)
1191 goto fork_out;
1192
1193 retval = -ENOMEM;
1194 p = dup_task_struct(current);
1195 if (!p)
1196 goto fork_out;
1197
1198 ftrace_graph_init_task(p);
1199 get_seccomp_filter(p);
1200
1201 rt_mutex_init_task(p);
1202
1203 #ifdef CONFIG_PROVE_LOCKING
1204 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1205 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1206 #endif
1207 retval = -EAGAIN;
1208 if (atomic_read(&p->real_cred->user->processes) >=
1209 task_rlimit(p, RLIMIT_NPROC)) {
1210 if (p->real_cred->user != INIT_USER &&
1211 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
1212 goto bad_fork_free;
1213 }
1214 current->flags &= ~PF_NPROC_EXCEEDED;
1215
1216 retval = copy_creds(p, clone_flags);
1217 if (retval < 0)
1218 goto bad_fork_free;
1219
1220 /*
1221 * If multiple threads are within copy_process(), then this check
1222 * triggers too late. This doesn't hurt, the check is only there
1223 * to stop root fork bombs.
1224 */
1225 retval = -EAGAIN;
1226 if (nr_threads >= max_threads)
1227 goto bad_fork_cleanup_count;
1228
1229 if (!try_module_get(task_thread_info(p)->exec_domain->module))
1230 goto bad_fork_cleanup_count;
1231
1232 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1233 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER);
1234 p->flags |= PF_FORKNOEXEC;
1235 INIT_LIST_HEAD(&p->children);
1236 INIT_LIST_HEAD(&p->sibling);
1237 rcu_copy_process(p);
1238 p->vfork_done = NULL;
1239 spin_lock_init(&p->alloc_lock);
1240
1241 init_sigpending(&p->pending);
1242
1243 p->utime = p->stime = p->gtime = 0;
1244 p->utimescaled = p->stimescaled = 0;
1245 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
1246 p->prev_cputime.utime = p->prev_cputime.stime = 0;
1247 #endif
1248 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1249 seqlock_init(&p->vtime_seqlock);
1250 p->vtime_snap = 0;
1251 p->vtime_snap_whence = VTIME_SLEEPING;
1252 #endif
1253
1254 #if defined(SPLIT_RSS_COUNTING)
1255 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1256 #endif
1257
1258 p->default_timer_slack_ns = current->timer_slack_ns;
1259
1260 task_io_accounting_init(&p->ioac);
1261 acct_clear_integrals(p);
1262
1263 posix_cpu_timers_init(p);
1264
1265 do_posix_clock_monotonic_gettime(&p->start_time);
1266 p->real_start_time = p->start_time;
1267 monotonic_to_bootbased(&p->real_start_time);
1268 p->io_context = NULL;
1269 p->audit_context = NULL;
1270 if (clone_flags & CLONE_THREAD)
1271 threadgroup_change_begin(current);
1272 cgroup_fork(p);
1273 #ifdef CONFIG_NUMA
1274 p->mempolicy = mpol_dup(p->mempolicy);
1275 if (IS_ERR(p->mempolicy)) {
1276 retval = PTR_ERR(p->mempolicy);
1277 p->mempolicy = NULL;
1278 goto bad_fork_cleanup_threadgroup_lock;
1279 }
1280 #endif
1281 #ifdef CONFIG_CPUSETS
1282 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1283 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1284 seqcount_init(&p->mems_allowed_seq);
1285 #endif
1286 #ifdef CONFIG_TRACE_IRQFLAGS
1287 p->irq_events = 0;
1288 p->hardirqs_enabled = 0;
1289 p->hardirq_enable_ip = 0;
1290 p->hardirq_enable_event = 0;
1291 p->hardirq_disable_ip = _THIS_IP_;
1292 p->hardirq_disable_event = 0;
1293 p->softirqs_enabled = 1;
1294 p->softirq_enable_ip = _THIS_IP_;
1295 p->softirq_enable_event = 0;
1296 p->softirq_disable_ip = 0;
1297 p->softirq_disable_event = 0;
1298 p->hardirq_context = 0;
1299 p->softirq_context = 0;
1300 #endif
1301 #ifdef CONFIG_LOCKDEP
1302 p->lockdep_depth = 0; /* no locks held yet */
1303 p->curr_chain_key = 0;
1304 p->lockdep_recursion = 0;
1305 #endif
1306
1307 #ifdef CONFIG_DEBUG_MUTEXES
1308 p->blocked_on = NULL; /* not blocked yet */
1309 #endif
1310 #ifdef CONFIG_MEMCG
1311 p->memcg_batch.do_batch = 0;
1312 p->memcg_batch.memcg = NULL;
1313 #endif
1314 #ifdef CONFIG_BCACHE
1315 p->sequential_io = 0;
1316 p->sequential_io_avg = 0;
1317 #endif
1318
1319 /* Perform scheduler related setup. Assign this task to a CPU. */
1320 retval = sched_fork(clone_flags, p);
1321 if (retval)
1322 goto bad_fork_cleanup_policy;
1323
1324 retval = perf_event_init_task(p);
1325 if (retval)
1326 goto bad_fork_cleanup_policy;
1327 retval = audit_alloc(p);
1328 if (retval)
1329 goto bad_fork_cleanup_policy;
1330 /* copy all the process information */
1331 retval = copy_semundo(clone_flags, p);
1332 if (retval)
1333 goto bad_fork_cleanup_audit;
1334 retval = copy_files(clone_flags, p);
1335 if (retval)
1336 goto bad_fork_cleanup_semundo;
1337 retval = copy_fs(clone_flags, p);
1338 if (retval)
1339 goto bad_fork_cleanup_files;
1340 retval = copy_sighand(clone_flags, p);
1341 if (retval)
1342 goto bad_fork_cleanup_fs;
1343 retval = copy_signal(clone_flags, p);
1344 if (retval)
1345 goto bad_fork_cleanup_sighand;
1346 retval = copy_mm(clone_flags, p);
1347 if (retval)
1348 goto bad_fork_cleanup_signal;
1349 retval = copy_namespaces(clone_flags, p);
1350 if (retval)
1351 goto bad_fork_cleanup_mm;
1352 retval = copy_io(clone_flags, p);
1353 if (retval)
1354 goto bad_fork_cleanup_namespaces;
1355 retval = copy_thread(clone_flags, stack_start, stack_size, p);
1356 if (retval)
1357 goto bad_fork_cleanup_io;
1358
1359 if (pid != &init_struct_pid) {
1360 retval = -ENOMEM;
1361 pid = alloc_pid(p->nsproxy->pid_ns_for_children);
1362 if (!pid)
1363 goto bad_fork_cleanup_io;
1364 }
1365
1366 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1367 /*
1368 * Clear TID on mm_release()?
1369 */
1370 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1371 #ifdef CONFIG_BLOCK
1372 p->plug = NULL;
1373 #endif
1374 #ifdef CONFIG_FUTEX
1375 p->robust_list = NULL;
1376 #ifdef CONFIG_COMPAT
1377 p->compat_robust_list = NULL;
1378 #endif
1379 INIT_LIST_HEAD(&p->pi_state_list);
1380 p->pi_state_cache = NULL;
1381 #endif
1382 /*
1383 * sigaltstack should be cleared when sharing the same VM
1384 */
1385 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1386 p->sas_ss_sp = p->sas_ss_size = 0;
1387
1388 /*
1389 * Syscall tracing and stepping should be turned off in the
1390 * child regardless of CLONE_PTRACE.
1391 */
1392 user_disable_single_step(p);
1393 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1394 #ifdef TIF_SYSCALL_EMU
1395 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1396 #endif
1397 clear_all_latency_tracing(p);
1398
1399 /* ok, now we should be set up.. */
1400 p->pid = pid_nr(pid);
1401 if (clone_flags & CLONE_THREAD) {
1402 p->exit_signal = -1;
1403 p->group_leader = current->group_leader;
1404 p->tgid = current->tgid;
1405 } else {
1406 if (clone_flags & CLONE_PARENT)
1407 p->exit_signal = current->group_leader->exit_signal;
1408 else
1409 p->exit_signal = (clone_flags & CSIGNAL);
1410 p->group_leader = p;
1411 p->tgid = p->pid;
1412 }
1413
1414 p->nr_dirtied = 0;
1415 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1416 p->dirty_paused_when = 0;
1417
1418 p->pdeath_signal = 0;
1419 INIT_LIST_HEAD(&p->thread_group);
1420 p->task_works = NULL;
1421
1422 /*
1423 * Make it visible to the rest of the system, but dont wake it up yet.
1424 * Need tasklist lock for parent etc handling!
1425 */
1426 write_lock_irq(&tasklist_lock);
1427
1428 /* CLONE_PARENT re-uses the old parent */
1429 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1430 p->real_parent = current->real_parent;
1431 p->parent_exec_id = current->parent_exec_id;
1432 } else {
1433 p->real_parent = current;
1434 p->parent_exec_id = current->self_exec_id;
1435 }
1436
1437 spin_lock(&current->sighand->siglock);
1438
1439 /*
1440 * Process group and session signals need to be delivered to just the
1441 * parent before the fork or both the parent and the child after the
1442 * fork. Restart if a signal comes in before we add the new process to
1443 * it's process group.
1444 * A fatal signal pending means that current will exit, so the new
1445 * thread can't slip out of an OOM kill (or normal SIGKILL).
1446 */
1447 recalc_sigpending();
1448 if (signal_pending(current)) {
1449 spin_unlock(&current->sighand->siglock);
1450 write_unlock_irq(&tasklist_lock);
1451 retval = -ERESTARTNOINTR;
1452 goto bad_fork_free_pid;
1453 }
1454
1455 if (likely(p->pid)) {
1456 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
1457
1458 init_task_pid(p, PIDTYPE_PID, pid);
1459 if (thread_group_leader(p)) {
1460 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
1461 init_task_pid(p, PIDTYPE_SID, task_session(current));
1462
1463 if (is_child_reaper(pid)) {
1464 ns_of_pid(pid)->child_reaper = p;
1465 p->signal->flags |= SIGNAL_UNKILLABLE;
1466 }
1467
1468 p->signal->leader_pid = pid;
1469 p->signal->tty = tty_kref_get(current->signal->tty);
1470 list_add_tail(&p->sibling, &p->real_parent->children);
1471 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1472 attach_pid(p, PIDTYPE_PGID);
1473 attach_pid(p, PIDTYPE_SID);
1474 __this_cpu_inc(process_counts);
1475 } else {
1476 current->signal->nr_threads++;
1477 atomic_inc(&current->signal->live);
1478 atomic_inc(&current->signal->sigcnt);
1479 list_add_tail_rcu(&p->thread_group,
1480 &p->group_leader->thread_group);
1481 list_add_tail_rcu(&p->thread_node,
1482 &p->signal->thread_head);
1483 }
1484 attach_pid(p, PIDTYPE_PID);
1485 nr_threads++;
1486 }
1487
1488 total_forks++;
1489 spin_unlock(&current->sighand->siglock);
1490 syscall_tracepoint_update(p);
1491 write_unlock_irq(&tasklist_lock);
1492
1493 proc_fork_connector(p);
1494 cgroup_post_fork(p);
1495 if (clone_flags & CLONE_THREAD)
1496 threadgroup_change_end(current);
1497 perf_event_fork(p);
1498
1499 trace_task_newtask(p, clone_flags);
1500 uprobe_copy_process(p, clone_flags);
1501
1502 return p;
1503
1504 bad_fork_free_pid:
1505 if (pid != &init_struct_pid)
1506 free_pid(pid);
1507 bad_fork_cleanup_io:
1508 if (p->io_context)
1509 exit_io_context(p);
1510 bad_fork_cleanup_namespaces:
1511 exit_task_namespaces(p);
1512 bad_fork_cleanup_mm:
1513 if (p->mm)
1514 mmput(p->mm);
1515 bad_fork_cleanup_signal:
1516 if (!(clone_flags & CLONE_THREAD))
1517 free_signal_struct(p->signal);
1518 bad_fork_cleanup_sighand:
1519 __cleanup_sighand(p->sighand);
1520 bad_fork_cleanup_fs:
1521 exit_fs(p); /* blocking */
1522 bad_fork_cleanup_files:
1523 exit_files(p); /* blocking */
1524 bad_fork_cleanup_semundo:
1525 exit_sem(p);
1526 bad_fork_cleanup_audit:
1527 audit_free(p);
1528 bad_fork_cleanup_policy:
1529 perf_event_free_task(p);
1530 #ifdef CONFIG_NUMA
1531 mpol_put(p->mempolicy);
1532 bad_fork_cleanup_threadgroup_lock:
1533 #endif
1534 if (clone_flags & CLONE_THREAD)
1535 threadgroup_change_end(current);
1536 delayacct_tsk_free(p);
1537 module_put(task_thread_info(p)->exec_domain->module);
1538 bad_fork_cleanup_count:
1539 atomic_dec(&p->cred->user->processes);
1540 exit_creds(p);
1541 bad_fork_free:
1542 free_task(p);
1543 fork_out:
1544 return ERR_PTR(retval);
1545 }
1546
1547 static inline void init_idle_pids(struct pid_link *links)
1548 {
1549 enum pid_type type;
1550
1551 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1552 INIT_HLIST_NODE(&links[type].node); /* not really needed */
1553 links[type].pid = &init_struct_pid;
1554 }
1555 }
1556
1557 struct task_struct *fork_idle(int cpu)
1558 {
1559 struct task_struct *task;
1560 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0);
1561 if (!IS_ERR(task)) {
1562 init_idle_pids(task->pids);
1563 init_idle(task, cpu);
1564 }
1565
1566 return task;
1567 }
1568
1569 /*
1570 * Ok, this is the main fork-routine.
1571 *
1572 * It copies the process, and if successful kick-starts
1573 * it and waits for it to finish using the VM if required.
1574 */
1575 long do_fork(unsigned long clone_flags,
1576 unsigned long stack_start,
1577 unsigned long stack_size,
1578 int __user *parent_tidptr,
1579 int __user *child_tidptr)
1580 {
1581 struct task_struct *p;
1582 int trace = 0;
1583 long nr;
1584
1585 /*
1586 * Determine whether and which event to report to ptracer. When
1587 * called from kernel_thread or CLONE_UNTRACED is explicitly
1588 * requested, no event is reported; otherwise, report if the event
1589 * for the type of forking is enabled.
1590 */
1591 if (!(clone_flags & CLONE_UNTRACED)) {
1592 if (clone_flags & CLONE_VFORK)
1593 trace = PTRACE_EVENT_VFORK;
1594 else if ((clone_flags & CSIGNAL) != SIGCHLD)
1595 trace = PTRACE_EVENT_CLONE;
1596 else
1597 trace = PTRACE_EVENT_FORK;
1598
1599 if (likely(!ptrace_event_enabled(current, trace)))
1600 trace = 0;
1601 }
1602
1603 p = copy_process(clone_flags, stack_start, stack_size,
1604 child_tidptr, NULL, trace);
1605 /*
1606 * Do this prior waking up the new thread - the thread pointer
1607 * might get invalid after that point, if the thread exits quickly.
1608 */
1609 if (!IS_ERR(p)) {
1610 struct completion vfork;
1611 struct pid *pid;
1612
1613 trace_sched_process_fork(current, p);
1614
1615 pid = get_task_pid(p, PIDTYPE_PID);
1616 nr = pid_vnr(pid);
1617
1618 if (clone_flags & CLONE_PARENT_SETTID)
1619 put_user(nr, parent_tidptr);
1620
1621 if (clone_flags & CLONE_VFORK) {
1622 p->vfork_done = &vfork;
1623 init_completion(&vfork);
1624 get_task_struct(p);
1625 }
1626
1627 wake_up_new_task(p);
1628
1629 /* forking complete and child started to run, tell ptracer */
1630 if (unlikely(trace))
1631 ptrace_event_pid(trace, pid);
1632
1633 if (clone_flags & CLONE_VFORK) {
1634 if (!wait_for_vfork_done(p, &vfork))
1635 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
1636 }
1637
1638 put_pid(pid);
1639 } else {
1640 nr = PTR_ERR(p);
1641 }
1642 return nr;
1643 }
1644
1645 /*
1646 * Create a kernel thread.
1647 */
1648 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
1649 {
1650 return do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
1651 (unsigned long)arg, NULL, NULL);
1652 }
1653
1654 #ifdef __ARCH_WANT_SYS_FORK
1655 SYSCALL_DEFINE0(fork)
1656 {
1657 #ifdef CONFIG_MMU
1658 return do_fork(SIGCHLD, 0, 0, NULL, NULL);
1659 #else
1660 /* can not support in nommu mode */
1661 return -EINVAL;
1662 #endif
1663 }
1664 #endif
1665
1666 #ifdef __ARCH_WANT_SYS_VFORK
1667 SYSCALL_DEFINE0(vfork)
1668 {
1669 return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
1670 0, NULL, NULL);
1671 }
1672 #endif
1673
1674 #ifdef __ARCH_WANT_SYS_CLONE
1675 #ifdef CONFIG_CLONE_BACKWARDS
1676 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
1677 int __user *, parent_tidptr,
1678 int, tls_val,
1679 int __user *, child_tidptr)
1680 #elif defined(CONFIG_CLONE_BACKWARDS2)
1681 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
1682 int __user *, parent_tidptr,
1683 int __user *, child_tidptr,
1684 int, tls_val)
1685 #elif defined(CONFIG_CLONE_BACKWARDS3)
1686 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
1687 int, stack_size,
1688 int __user *, parent_tidptr,
1689 int __user *, child_tidptr,
1690 int, tls_val)
1691 #else
1692 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
1693 int __user *, parent_tidptr,
1694 int __user *, child_tidptr,
1695 int, tls_val)
1696 #endif
1697 {
1698 return do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr);
1699 }
1700 #endif
1701
1702 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1703 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1704 #endif
1705
1706 static void sighand_ctor(void *data)
1707 {
1708 struct sighand_struct *sighand = data;
1709
1710 spin_lock_init(&sighand->siglock);
1711 init_waitqueue_head(&sighand->signalfd_wqh);
1712 }
1713
1714 void __init proc_caches_init(void)
1715 {
1716 sighand_cachep = kmem_cache_create("sighand_cache",
1717 sizeof(struct sighand_struct), 0,
1718 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_DESTROY_BY_RCU|
1719 SLAB_NOTRACK, sighand_ctor);
1720 signal_cachep = kmem_cache_create("signal_cache",
1721 sizeof(struct signal_struct), 0,
1722 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1723 files_cachep = kmem_cache_create("files_cache",
1724 sizeof(struct files_struct), 0,
1725 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1726 fs_cachep = kmem_cache_create("fs_cache",
1727 sizeof(struct fs_struct), 0,
1728 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1729 /*
1730 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1731 * whole struct cpumask for the OFFSTACK case. We could change
1732 * this to *only* allocate as much of it as required by the
1733 * maximum number of CPU's we can ever have. The cpumask_allocation
1734 * is at the end of the structure, exactly for that reason.
1735 */
1736 mm_cachep = kmem_cache_create("mm_struct",
1737 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
1738 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_NOTRACK, NULL);
1739 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC);
1740 mmap_init();
1741 nsproxy_cache_init();
1742 }
1743
1744 /*
1745 * Check constraints on flags passed to the unshare system call.
1746 */
1747 static int check_unshare_flags(unsigned long unshare_flags)
1748 {
1749 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
1750 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
1751 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
1752 CLONE_NEWUSER|CLONE_NEWPID))
1753 return -EINVAL;
1754 /*
1755 * Not implemented, but pretend it works if there is nothing to
1756 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1757 * needs to unshare vm.
1758 */
1759 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
1760 /* FIXME: get_task_mm() increments ->mm_users */
1761 if (atomic_read(&current->mm->mm_users) > 1)
1762 return -EINVAL;
1763 }
1764
1765 return 0;
1766 }
1767
1768 /*
1769 * Unshare the filesystem structure if it is being shared
1770 */
1771 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
1772 {
1773 struct fs_struct *fs = current->fs;
1774
1775 if (!(unshare_flags & CLONE_FS) || !fs)
1776 return 0;
1777
1778 /* don't need lock here; in the worst case we'll do useless copy */
1779 if (fs->users == 1)
1780 return 0;
1781
1782 *new_fsp = copy_fs_struct(fs);
1783 if (!*new_fsp)
1784 return -ENOMEM;
1785
1786 return 0;
1787 }
1788
1789 /*
1790 * Unshare file descriptor table if it is being shared
1791 */
1792 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
1793 {
1794 struct files_struct *fd = current->files;
1795 int error = 0;
1796
1797 if ((unshare_flags & CLONE_FILES) &&
1798 (fd && atomic_read(&fd->count) > 1)) {
1799 *new_fdp = dup_fd(fd, &error);
1800 if (!*new_fdp)
1801 return error;
1802 }
1803
1804 return 0;
1805 }
1806
1807 /*
1808 * unshare allows a process to 'unshare' part of the process
1809 * context which was originally shared using clone. copy_*
1810 * functions used by do_fork() cannot be used here directly
1811 * because they modify an inactive task_struct that is being
1812 * constructed. Here we are modifying the current, active,
1813 * task_struct.
1814 */
1815 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
1816 {
1817 struct fs_struct *fs, *new_fs = NULL;
1818 struct files_struct *fd, *new_fd = NULL;
1819 struct cred *new_cred = NULL;
1820 struct nsproxy *new_nsproxy = NULL;
1821 int do_sysvsem = 0;
1822 int err;
1823
1824 /*
1825 * If unsharing a user namespace must also unshare the thread.
1826 */
1827 if (unshare_flags & CLONE_NEWUSER)
1828 unshare_flags |= CLONE_THREAD | CLONE_FS;
1829 /*
1830 * If unsharing a thread from a thread group, must also unshare vm.
1831 */
1832 if (unshare_flags & CLONE_THREAD)
1833 unshare_flags |= CLONE_VM;
1834 /*
1835 * If unsharing vm, must also unshare signal handlers.
1836 */
1837 if (unshare_flags & CLONE_VM)
1838 unshare_flags |= CLONE_SIGHAND;
1839 /*
1840 * If unsharing namespace, must also unshare filesystem information.
1841 */
1842 if (unshare_flags & CLONE_NEWNS)
1843 unshare_flags |= CLONE_FS;
1844
1845 err = check_unshare_flags(unshare_flags);
1846 if (err)
1847 goto bad_unshare_out;
1848 /*
1849 * CLONE_NEWIPC must also detach from the undolist: after switching
1850 * to a new ipc namespace, the semaphore arrays from the old
1851 * namespace are unreachable.
1852 */
1853 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
1854 do_sysvsem = 1;
1855 err = unshare_fs(unshare_flags, &new_fs);
1856 if (err)
1857 goto bad_unshare_out;
1858 err = unshare_fd(unshare_flags, &new_fd);
1859 if (err)
1860 goto bad_unshare_cleanup_fs;
1861 err = unshare_userns(unshare_flags, &new_cred);
1862 if (err)
1863 goto bad_unshare_cleanup_fd;
1864 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
1865 new_cred, new_fs);
1866 if (err)
1867 goto bad_unshare_cleanup_cred;
1868
1869 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
1870 if (do_sysvsem) {
1871 /*
1872 * CLONE_SYSVSEM is equivalent to sys_exit().
1873 */
1874 exit_sem(current);
1875 }
1876
1877 if (new_nsproxy)
1878 switch_task_namespaces(current, new_nsproxy);
1879
1880 task_lock(current);
1881
1882 if (new_fs) {
1883 fs = current->fs;
1884 spin_lock(&fs->lock);
1885 current->fs = new_fs;
1886 if (--fs->users)
1887 new_fs = NULL;
1888 else
1889 new_fs = fs;
1890 spin_unlock(&fs->lock);
1891 }
1892
1893 if (new_fd) {
1894 fd = current->files;
1895 current->files = new_fd;
1896 new_fd = fd;
1897 }
1898
1899 task_unlock(current);
1900
1901 if (new_cred) {
1902 /* Install the new user namespace */
1903 commit_creds(new_cred);
1904 new_cred = NULL;
1905 }
1906 }
1907
1908 bad_unshare_cleanup_cred:
1909 if (new_cred)
1910 put_cred(new_cred);
1911 bad_unshare_cleanup_fd:
1912 if (new_fd)
1913 put_files_struct(new_fd);
1914
1915 bad_unshare_cleanup_fs:
1916 if (new_fs)
1917 free_fs_struct(new_fs);
1918
1919 bad_unshare_out:
1920 return err;
1921 }
1922
1923 /*
1924 * Helper to unshare the files of the current task.
1925 * We don't want to expose copy_files internals to
1926 * the exec layer of the kernel.
1927 */
1928
1929 int unshare_files(struct files_struct **displaced)
1930 {
1931 struct task_struct *task = current;
1932 struct files_struct *copy = NULL;
1933 int error;
1934
1935 error = unshare_fd(CLONE_FILES, &copy);
1936 if (error || !copy) {
1937 *displaced = NULL;
1938 return error;
1939 }
1940 *displaced = task->files;
1941 task_lock(task);
1942 task->files = copy;
1943 task_unlock(task);
1944 return 0;
1945 }
Linux kernel - Deliverables
This page took 0.069678 seconds and 5 git commands to generate.