4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
14 #include <linux/slab.h>
15 #include <linux/sched/autogroup.h>
16 #include <linux/sched/mm.h>
17 #include <linux/sched/coredump.h>
18 #include <linux/sched/user.h>
19 #include <linux/sched/numa_balancing.h>
20 #include <linux/sched/stat.h>
21 #include <linux/sched/task.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/sched/cputime.h>
24 #include <linux/rtmutex.h>
25 #include <linux/init.h>
26 #include <linux/unistd.h>
27 #include <linux/module.h>
28 #include <linux/vmalloc.h>
29 #include <linux/completion.h>
30 #include <linux/personality.h>
31 #include <linux/mempolicy.h>
32 #include <linux/sem.h>
33 #include <linux/file.h>
34 #include <linux/fdtable.h>
35 #include <linux/iocontext.h>
36 #include <linux/key.h>
37 #include <linux/binfmts.h>
38 #include <linux/mman.h>
39 #include <linux/mmu_notifier.h>
40 #include <linux/hmm.h>
43 #include <linux/vmacache.h>
44 #include <linux/nsproxy.h>
45 #include <linux/capability.h>
46 #include <linux/cpu.h>
47 #include <linux/cgroup.h>
48 #include <linux/security.h>
49 #include <linux/hugetlb.h>
50 #include <linux/seccomp.h>
51 #include <linux/swap.h>
52 #include <linux/syscalls.h>
53 #include <linux/jiffies.h>
54 #include <linux/futex.h>
55 #include <linux/compat.h>
56 #include <linux/kthread.h>
57 #include <linux/task_io_accounting_ops.h>
58 #include <linux/rcupdate.h>
59 #include <linux/ptrace.h>
60 #include <linux/mount.h>
61 #include <linux/audit.h>
62 #include <linux/memcontrol.h>
63 #include <linux/ftrace.h>
64 #include <linux/proc_fs.h>
65 #include <linux/profile.h>
66 #include <linux/rmap.h>
67 #include <linux/ksm.h>
68 #include <linux/acct.h>
69 #include <linux/userfaultfd_k.h>
70 #include <linux/tsacct_kern.h>
71 #include <linux/cn_proc.h>
72 #include <linux/freezer.h>
73 #include <linux/delayacct.h>
74 #include <linux/taskstats_kern.h>
75 #include <linux/random.h>
76 #include <linux/tty.h>
77 #include <linux/blkdev.h>
78 #include <linux/fs_struct.h>
79 #include <linux/magic.h>
80 #include <linux/sched/mm.h>
81 #include <linux/perf_event.h>
82 #include <linux/posix-timers.h>
83 #include <linux/user-return-notifier.h>
84 #include <linux/oom.h>
85 #include <linux/khugepaged.h>
86 #include <linux/signalfd.h>
87 #include <linux/uprobes.h>
88 #include <linux/aio.h>
89 #include <linux/compiler.h>
90 #include <linux/sysctl.h>
91 #include <linux/kcov.h>
92 #include <linux/livepatch.h>
93 #include <linux/thread_info.h>
95 #include <asm/pgtable.h>
96 #include <asm/pgalloc.h>
97 #include <linux/uaccess.h>
98 #include <asm/mmu_context.h>
99 #include <asm/cacheflush.h>
100 #include <asm/tlbflush.h>
102 #include <trace/events/sched.h>
104 #define CREATE_TRACE_POINTS
105 #include <trace/events/task.h>
108 * Minimum number of threads to boot the kernel
110 #define MIN_THREADS 20
113 * Maximum number of threads
115 #define MAX_THREADS FUTEX_TID_MASK
118 * Protected counters by write_lock_irq(&tasklist_lock)
120 unsigned long total_forks; /* Handle normal Linux uptimes. */
121 int nr_threads; /* The idle threads do not count.. */
123 int max_threads; /* tunable limit on nr_threads */
125 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
127 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
129 #ifdef CONFIG_PROVE_RCU
130 int lockdep_tasklist_lock_is_held(void)
132 return lockdep_is_held(&tasklist_lock);
134 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
135 #endif /* #ifdef CONFIG_PROVE_RCU */
137 int nr_processes(void)
142 for_each_possible_cpu(cpu)
143 total += per_cpu(process_counts, cpu);
148 void __weak arch_release_task_struct(struct task_struct *tsk)
152 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
153 static struct kmem_cache *task_struct_cachep;
155 static inline struct task_struct *alloc_task_struct_node(int node)
157 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
160 static inline void free_task_struct(struct task_struct *tsk)
162 kmem_cache_free(task_struct_cachep, tsk);
166 void __weak arch_release_thread_stack(unsigned long *stack)
170 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
173 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
174 * kmemcache based allocator.
176 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
178 #ifdef CONFIG_VMAP_STACK
180 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
181 * flush. Try to minimize the number of calls by caching stacks.
183 #define NR_CACHED_STACKS 2
184 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
186 static int free_vm_stack_cache(unsigned int cpu)
188 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
191 for (i = 0; i < NR_CACHED_STACKS; i++) {
192 struct vm_struct *vm_stack = cached_vm_stacks[i];
197 vfree(vm_stack->addr);
198 cached_vm_stacks[i] = NULL;
205 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
207 #ifdef CONFIG_VMAP_STACK
211 for (i = 0; i < NR_CACHED_STACKS; i++) {
214 s = this_cpu_xchg(cached_stacks[i], NULL);
219 #ifdef CONFIG_DEBUG_KMEMLEAK
220 /* Clear stale pointers from reused stack. */
221 memset(s->addr, 0, THREAD_SIZE);
223 tsk->stack_vm_area = s;
227 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
228 VMALLOC_START, VMALLOC_END,
231 0, node, __builtin_return_address(0));
234 * We can't call find_vm_area() in interrupt context, and
235 * free_thread_stack() can be called in interrupt context,
236 * so cache the vm_struct.
239 tsk->stack_vm_area = find_vm_area(stack);
242 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
245 return page ? page_address(page) : NULL;
249 static inline void free_thread_stack(struct task_struct *tsk)
251 #ifdef CONFIG_VMAP_STACK
252 if (task_stack_vm_area(tsk)) {
255 for (i = 0; i < NR_CACHED_STACKS; i++) {
256 if (this_cpu_cmpxchg(cached_stacks[i],
257 NULL, tsk->stack_vm_area) != NULL)
263 vfree_atomic(tsk->stack);
268 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
271 static struct kmem_cache *thread_stack_cache;
273 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
276 return kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
279 static void free_thread_stack(struct task_struct *tsk)
281 kmem_cache_free(thread_stack_cache, tsk->stack);
284 void thread_stack_cache_init(void)
286 thread_stack_cache = kmem_cache_create("thread_stack", THREAD_SIZE,
287 THREAD_SIZE, 0, NULL);
288 BUG_ON(thread_stack_cache == NULL);
293 /* SLAB cache for signal_struct structures (tsk->signal) */
294 static struct kmem_cache *signal_cachep;
296 /* SLAB cache for sighand_struct structures (tsk->sighand) */
297 struct kmem_cache *sighand_cachep;
299 /* SLAB cache for files_struct structures (tsk->files) */
300 struct kmem_cache *files_cachep;
302 /* SLAB cache for fs_struct structures (tsk->fs) */
303 struct kmem_cache *fs_cachep;
305 /* SLAB cache for vm_area_struct structures */
306 struct kmem_cache *vm_area_cachep;
308 /* SLAB cache for mm_struct structures (tsk->mm) */
309 static struct kmem_cache *mm_cachep;
311 static void account_kernel_stack(struct task_struct *tsk, int account)
313 void *stack = task_stack_page(tsk);
314 struct vm_struct *vm = task_stack_vm_area(tsk);
316 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
321 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
323 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
324 mod_zone_page_state(page_zone(vm->pages[i]),
326 PAGE_SIZE / 1024 * account);
329 /* All stack pages belong to the same memcg. */
330 mod_memcg_page_state(vm->pages[0], MEMCG_KERNEL_STACK_KB,
331 account * (THREAD_SIZE / 1024));
334 * All stack pages are in the same zone and belong to the
337 struct page *first_page = virt_to_page(stack);
339 mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
340 THREAD_SIZE / 1024 * account);
342 mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
343 account * (THREAD_SIZE / 1024));
347 static void release_task_stack(struct task_struct *tsk)
349 if (WARN_ON(tsk->state != TASK_DEAD))
350 return; /* Better to leak the stack than to free prematurely */
352 account_kernel_stack(tsk, -1);
353 arch_release_thread_stack(tsk->stack);
354 free_thread_stack(tsk);
356 #ifdef CONFIG_VMAP_STACK
357 tsk->stack_vm_area = NULL;
361 #ifdef CONFIG_THREAD_INFO_IN_TASK
362 void put_task_stack(struct task_struct *tsk)
364 if (atomic_dec_and_test(&tsk->stack_refcount))
365 release_task_stack(tsk);
369 void free_task(struct task_struct *tsk)
371 #ifndef CONFIG_THREAD_INFO_IN_TASK
373 * The task is finally done with both the stack and thread_info,
376 release_task_stack(tsk);
379 * If the task had a separate stack allocation, it should be gone
382 WARN_ON_ONCE(atomic_read(&tsk->stack_refcount) != 0);
384 rt_mutex_debug_task_free(tsk);
385 ftrace_graph_exit_task(tsk);
386 put_seccomp_filter(tsk);
387 arch_release_task_struct(tsk);
388 if (tsk->flags & PF_KTHREAD)
389 free_kthread_struct(tsk);
390 free_task_struct(tsk);
392 EXPORT_SYMBOL(free_task);
395 static __latent_entropy int dup_mmap(struct mm_struct *mm,
396 struct mm_struct *oldmm)
398 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
399 struct rb_node **rb_link, *rb_parent;
401 unsigned long charge;
404 uprobe_start_dup_mmap();
405 if (down_write_killable(&oldmm->mmap_sem)) {
407 goto fail_uprobe_end;
409 flush_cache_dup_mm(oldmm);
410 uprobe_dup_mmap(oldmm, mm);
412 * Not linked in yet - no deadlock potential:
414 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
416 /* No ordering required: file already has been exposed. */
417 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
419 mm->total_vm = oldmm->total_vm;
420 mm->data_vm = oldmm->data_vm;
421 mm->exec_vm = oldmm->exec_vm;
422 mm->stack_vm = oldmm->stack_vm;
424 rb_link = &mm->mm_rb.rb_node;
427 retval = ksm_fork(mm, oldmm);
430 retval = khugepaged_fork(mm, oldmm);
435 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
438 if (mpnt->vm_flags & VM_DONTCOPY) {
439 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
443 if (mpnt->vm_flags & VM_ACCOUNT) {
444 unsigned long len = vma_pages(mpnt);
446 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
450 tmp = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
454 INIT_LIST_HEAD(&tmp->anon_vma_chain);
455 retval = vma_dup_policy(mpnt, tmp);
457 goto fail_nomem_policy;
459 retval = dup_userfaultfd(tmp, &uf);
461 goto fail_nomem_anon_vma_fork;
462 if (tmp->vm_flags & VM_WIPEONFORK) {
463 /* VM_WIPEONFORK gets a clean slate in the child. */
464 tmp->anon_vma = NULL;
465 if (anon_vma_prepare(tmp))
466 goto fail_nomem_anon_vma_fork;
467 } else if (anon_vma_fork(tmp, mpnt))
468 goto fail_nomem_anon_vma_fork;
469 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
470 tmp->vm_next = tmp->vm_prev = NULL;
473 struct inode *inode = file_inode(file);
474 struct address_space *mapping = file->f_mapping;
477 if (tmp->vm_flags & VM_DENYWRITE)
478 atomic_dec(&inode->i_writecount);
479 i_mmap_lock_write(mapping);
480 if (tmp->vm_flags & VM_SHARED)
481 atomic_inc(&mapping->i_mmap_writable);
482 flush_dcache_mmap_lock(mapping);
483 /* insert tmp into the share list, just after mpnt */
484 vma_interval_tree_insert_after(tmp, mpnt,
486 flush_dcache_mmap_unlock(mapping);
487 i_mmap_unlock_write(mapping);
491 * Clear hugetlb-related page reserves for children. This only
492 * affects MAP_PRIVATE mappings. Faults generated by the child
493 * are not guaranteed to succeed, even if read-only
495 if (is_vm_hugetlb_page(tmp))
496 reset_vma_resv_huge_pages(tmp);
499 * Link in the new vma and copy the page table entries.
502 pprev = &tmp->vm_next;
506 __vma_link_rb(mm, tmp, rb_link, rb_parent);
507 rb_link = &tmp->vm_rb.rb_right;
508 rb_parent = &tmp->vm_rb;
511 if (!(tmp->vm_flags & VM_WIPEONFORK))
512 retval = copy_page_range(mm, oldmm, mpnt);
514 if (tmp->vm_ops && tmp->vm_ops->open)
515 tmp->vm_ops->open(tmp);
520 /* a new mm has just been created */
521 arch_dup_mmap(oldmm, mm);
524 up_write(&mm->mmap_sem);
526 up_write(&oldmm->mmap_sem);
527 dup_userfaultfd_complete(&uf);
529 uprobe_end_dup_mmap();
531 fail_nomem_anon_vma_fork:
532 mpol_put(vma_policy(tmp));
534 kmem_cache_free(vm_area_cachep, tmp);
537 vm_unacct_memory(charge);
541 static inline int mm_alloc_pgd(struct mm_struct *mm)
543 mm->pgd = pgd_alloc(mm);
544 if (unlikely(!mm->pgd))
549 static inline void mm_free_pgd(struct mm_struct *mm)
551 pgd_free(mm, mm->pgd);
554 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
556 down_write(&oldmm->mmap_sem);
557 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
558 up_write(&oldmm->mmap_sem);
561 #define mm_alloc_pgd(mm) (0)
562 #define mm_free_pgd(mm)
563 #endif /* CONFIG_MMU */
565 static void check_mm(struct mm_struct *mm)
569 for (i = 0; i < NR_MM_COUNTERS; i++) {
570 long x = atomic_long_read(&mm->rss_stat.count[i]);
573 printk(KERN_ALERT "BUG: Bad rss-counter state "
574 "mm:%p idx:%d val:%ld\n", mm, i, x);
577 if (mm_pgtables_bytes(mm))
578 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
579 mm_pgtables_bytes(mm));
581 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
582 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
586 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
587 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
590 * Called when the last reference to the mm
591 * is dropped: either by a lazy thread or by
592 * mmput. Free the page directory and the mm.
594 static void __mmdrop(struct mm_struct *mm)
596 BUG_ON(mm == &init_mm);
600 mmu_notifier_mm_destroy(mm);
602 put_user_ns(mm->user_ns);
606 void mmdrop(struct mm_struct *mm)
608 if (unlikely(atomic_dec_and_test(&mm->mm_count)))
611 EXPORT_SYMBOL_GPL(mmdrop);
613 static void mmdrop_async_fn(struct work_struct *work)
615 struct mm_struct *mm;
617 mm = container_of(work, struct mm_struct, async_put_work);
621 static void mmdrop_async(struct mm_struct *mm)
623 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
624 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
625 schedule_work(&mm->async_put_work);
629 static inline void free_signal_struct(struct signal_struct *sig)
631 taskstats_tgid_free(sig);
632 sched_autogroup_exit(sig);
634 * __mmdrop is not safe to call from softirq context on x86 due to
635 * pgd_dtor so postpone it to the async context
638 mmdrop_async(sig->oom_mm);
639 kmem_cache_free(signal_cachep, sig);
642 static inline void put_signal_struct(struct signal_struct *sig)
644 if (atomic_dec_and_test(&sig->sigcnt))
645 free_signal_struct(sig);
648 void __put_task_struct(struct task_struct *tsk)
650 WARN_ON(!tsk->exit_state);
651 WARN_ON(atomic_read(&tsk->usage));
652 WARN_ON(tsk == current);
656 security_task_free(tsk);
658 delayacct_tsk_free(tsk);
659 put_signal_struct(tsk->signal);
661 if (!profile_handoff_task(tsk))
664 EXPORT_SYMBOL_GPL(__put_task_struct);
666 void __init __weak arch_task_cache_init(void) { }
671 static void set_max_threads(unsigned int max_threads_suggested)
676 * The number of threads shall be limited such that the thread
677 * structures may only consume a small part of the available memory.
679 if (fls64(totalram_pages) + fls64(PAGE_SIZE) > 64)
680 threads = MAX_THREADS;
682 threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
683 (u64) THREAD_SIZE * 8UL);
685 if (threads > max_threads_suggested)
686 threads = max_threads_suggested;
688 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
691 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
692 /* Initialized by the architecture: */
693 int arch_task_struct_size __read_mostly;
696 void __init fork_init(void)
699 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
700 #ifndef ARCH_MIN_TASKALIGN
701 #define ARCH_MIN_TASKALIGN 0
703 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
705 /* create a slab on which task_structs can be allocated */
706 task_struct_cachep = kmem_cache_create("task_struct",
707 arch_task_struct_size, align,
708 SLAB_PANIC|SLAB_ACCOUNT, NULL);
711 /* do the arch specific task caches init */
712 arch_task_cache_init();
714 set_max_threads(MAX_THREADS);
716 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
717 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
718 init_task.signal->rlim[RLIMIT_SIGPENDING] =
719 init_task.signal->rlim[RLIMIT_NPROC];
721 for (i = 0; i < UCOUNT_COUNTS; i++) {
722 init_user_ns.ucount_max[i] = max_threads/2;
725 #ifdef CONFIG_VMAP_STACK
726 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
727 NULL, free_vm_stack_cache);
730 lockdep_init_task(&init_task);
733 int __weak arch_dup_task_struct(struct task_struct *dst,
734 struct task_struct *src)
740 void set_task_stack_end_magic(struct task_struct *tsk)
742 unsigned long *stackend;
744 stackend = end_of_stack(tsk);
745 *stackend = STACK_END_MAGIC; /* for overflow detection */
748 static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
750 struct task_struct *tsk;
751 unsigned long *stack;
752 struct vm_struct *stack_vm_area;
755 if (node == NUMA_NO_NODE)
756 node = tsk_fork_get_node(orig);
757 tsk = alloc_task_struct_node(node);
761 stack = alloc_thread_stack_node(tsk, node);
765 stack_vm_area = task_stack_vm_area(tsk);
767 err = arch_dup_task_struct(tsk, orig);
770 * arch_dup_task_struct() clobbers the stack-related fields. Make
771 * sure they're properly initialized before using any stack-related
775 #ifdef CONFIG_VMAP_STACK
776 tsk->stack_vm_area = stack_vm_area;
778 #ifdef CONFIG_THREAD_INFO_IN_TASK
779 atomic_set(&tsk->stack_refcount, 1);
785 #ifdef CONFIG_SECCOMP
787 * We must handle setting up seccomp filters once we're under
788 * the sighand lock in case orig has changed between now and
789 * then. Until then, filter must be NULL to avoid messing up
790 * the usage counts on the error path calling free_task.
792 tsk->seccomp.filter = NULL;
795 setup_thread_stack(tsk, orig);
796 clear_user_return_notifier(tsk);
797 clear_tsk_need_resched(tsk);
798 set_task_stack_end_magic(tsk);
800 #ifdef CONFIG_CC_STACKPROTECTOR
801 tsk->stack_canary = get_random_canary();
805 * One for us, one for whoever does the "release_task()" (usually
808 atomic_set(&tsk->usage, 2);
809 #ifdef CONFIG_BLK_DEV_IO_TRACE
812 tsk->splice_pipe = NULL;
813 tsk->task_frag.page = NULL;
814 tsk->wake_q.next = NULL;
816 account_kernel_stack(tsk, 1);
820 #ifdef CONFIG_FAULT_INJECTION
827 free_thread_stack(tsk);
829 free_task_struct(tsk);
833 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
835 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
837 static int __init coredump_filter_setup(char *s)
839 default_dump_filter =
840 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
841 MMF_DUMP_FILTER_MASK;
845 __setup("coredump_filter=", coredump_filter_setup);
847 #include <linux/init_task.h>
849 static void mm_init_aio(struct mm_struct *mm)
852 spin_lock_init(&mm->ioctx_lock);
853 mm->ioctx_table = NULL;
857 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
864 static void mm_init_uprobes_state(struct mm_struct *mm)
866 #ifdef CONFIG_UPROBES
867 mm->uprobes_state.xol_area = NULL;
871 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
872 struct user_namespace *user_ns)
876 mm->vmacache_seqnum = 0;
877 atomic_set(&mm->mm_users, 1);
878 atomic_set(&mm->mm_count, 1);
879 init_rwsem(&mm->mmap_sem);
880 INIT_LIST_HEAD(&mm->mmlist);
881 mm->core_state = NULL;
882 mm_pgtables_bytes_init(mm);
886 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
887 spin_lock_init(&mm->page_table_lock);
890 mm_init_owner(mm, p);
891 RCU_INIT_POINTER(mm->exe_file, NULL);
892 mmu_notifier_mm_init(mm);
894 init_tlb_flush_pending(mm);
895 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
896 mm->pmd_huge_pte = NULL;
898 mm_init_uprobes_state(mm);
901 mm->flags = current->mm->flags & MMF_INIT_MASK;
902 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
904 mm->flags = default_dump_filter;
908 if (mm_alloc_pgd(mm))
911 if (init_new_context(p, mm))
914 mm->user_ns = get_user_ns(user_ns);
925 * Allocate and initialize an mm_struct.
927 struct mm_struct *mm_alloc(void)
929 struct mm_struct *mm;
935 memset(mm, 0, sizeof(*mm));
936 return mm_init(mm, current, current_user_ns());
939 static inline void __mmput(struct mm_struct *mm)
941 VM_BUG_ON(atomic_read(&mm->mm_users));
943 uprobe_clear_state(mm);
946 khugepaged_exit(mm); /* must run before exit_mmap */
948 mm_put_huge_zero_page(mm);
949 set_mm_exe_file(mm, NULL);
950 if (!list_empty(&mm->mmlist)) {
951 spin_lock(&mmlist_lock);
952 list_del(&mm->mmlist);
953 spin_unlock(&mmlist_lock);
956 module_put(mm->binfmt->module);
961 * Decrement the use count and release all resources for an mm.
963 void mmput(struct mm_struct *mm)
967 if (atomic_dec_and_test(&mm->mm_users))
970 EXPORT_SYMBOL_GPL(mmput);
973 static void mmput_async_fn(struct work_struct *work)
975 struct mm_struct *mm = container_of(work, struct mm_struct,
981 void mmput_async(struct mm_struct *mm)
983 if (atomic_dec_and_test(&mm->mm_users)) {
984 INIT_WORK(&mm->async_put_work, mmput_async_fn);
985 schedule_work(&mm->async_put_work);
991 * set_mm_exe_file - change a reference to the mm's executable file
993 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
995 * Main users are mmput() and sys_execve(). Callers prevent concurrent
996 * invocations: in mmput() nobody alive left, in execve task is single
997 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
998 * mm->exe_file, but does so without using set_mm_exe_file() in order
999 * to do avoid the need for any locks.
1001 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1003 struct file *old_exe_file;
1006 * It is safe to dereference the exe_file without RCU as
1007 * this function is only called if nobody else can access
1008 * this mm -- see comment above for justification.
1010 old_exe_file = rcu_dereference_raw(mm->exe_file);
1013 get_file(new_exe_file);
1014 rcu_assign_pointer(mm->exe_file, new_exe_file);
1020 * get_mm_exe_file - acquire a reference to the mm's executable file
1022 * Returns %NULL if mm has no associated executable file.
1023 * User must release file via fput().
1025 struct file *get_mm_exe_file(struct mm_struct *mm)
1027 struct file *exe_file;
1030 exe_file = rcu_dereference(mm->exe_file);
1031 if (exe_file && !get_file_rcu(exe_file))
1036 EXPORT_SYMBOL(get_mm_exe_file);
1039 * get_task_exe_file - acquire a reference to the task's executable file
1041 * Returns %NULL if task's mm (if any) has no associated executable file or
1042 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1043 * User must release file via fput().
1045 struct file *get_task_exe_file(struct task_struct *task)
1047 struct file *exe_file = NULL;
1048 struct mm_struct *mm;
1053 if (!(task->flags & PF_KTHREAD))
1054 exe_file = get_mm_exe_file(mm);
1059 EXPORT_SYMBOL(get_task_exe_file);
1062 * get_task_mm - acquire a reference to the task's mm
1064 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1065 * this kernel workthread has transiently adopted a user mm with use_mm,
1066 * to do its AIO) is not set and if so returns a reference to it, after
1067 * bumping up the use count. User must release the mm via mmput()
1068 * after use. Typically used by /proc and ptrace.
1070 struct mm_struct *get_task_mm(struct task_struct *task)
1072 struct mm_struct *mm;
1077 if (task->flags & PF_KTHREAD)
1085 EXPORT_SYMBOL_GPL(get_task_mm);
1087 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1089 struct mm_struct *mm;
1092 err = mutex_lock_killable(&task->signal->cred_guard_mutex);
1094 return ERR_PTR(err);
1096 mm = get_task_mm(task);
1097 if (mm && mm != current->mm &&
1098 !ptrace_may_access(task, mode)) {
1100 mm = ERR_PTR(-EACCES);
1102 mutex_unlock(&task->signal->cred_guard_mutex);
1107 static void complete_vfork_done(struct task_struct *tsk)
1109 struct completion *vfork;
1112 vfork = tsk->vfork_done;
1113 if (likely(vfork)) {
1114 tsk->vfork_done = NULL;
1120 static int wait_for_vfork_done(struct task_struct *child,
1121 struct completion *vfork)
1125 freezer_do_not_count();
1126 killed = wait_for_completion_killable(vfork);
1131 child->vfork_done = NULL;
1135 put_task_struct(child);
1139 /* Please note the differences between mmput and mm_release.
1140 * mmput is called whenever we stop holding onto a mm_struct,
1141 * error success whatever.
1143 * mm_release is called after a mm_struct has been removed
1144 * from the current process.
1146 * This difference is important for error handling, when we
1147 * only half set up a mm_struct for a new process and need to restore
1148 * the old one. Because we mmput the new mm_struct before
1149 * restoring the old one. . .
1150 * Eric Biederman 10 January 1998
1152 void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1154 /* Get rid of any futexes when releasing the mm */
1156 if (unlikely(tsk->robust_list)) {
1157 exit_robust_list(tsk);
1158 tsk->robust_list = NULL;
1160 #ifdef CONFIG_COMPAT
1161 if (unlikely(tsk->compat_robust_list)) {
1162 compat_exit_robust_list(tsk);
1163 tsk->compat_robust_list = NULL;
1166 if (unlikely(!list_empty(&tsk->pi_state_list)))
1167 exit_pi_state_list(tsk);
1170 uprobe_free_utask(tsk);
1172 /* Get rid of any cached register state */
1173 deactivate_mm(tsk, mm);
1176 * Signal userspace if we're not exiting with a core dump
1177 * because we want to leave the value intact for debugging
1180 if (tsk->clear_child_tid) {
1181 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) &&
1182 atomic_read(&mm->mm_users) > 1) {
1184 * We don't check the error code - if userspace has
1185 * not set up a proper pointer then tough luck.
1187 put_user(0, tsk->clear_child_tid);
1188 sys_futex(tsk->clear_child_tid, FUTEX_WAKE,
1191 tsk->clear_child_tid = NULL;
1195 * All done, finally we can wake up parent and return this mm to him.
1196 * Also kthread_stop() uses this completion for synchronization.
1198 if (tsk->vfork_done)
1199 complete_vfork_done(tsk);
1203 * Allocate a new mm structure and copy contents from the
1204 * mm structure of the passed in task structure.
1206 static struct mm_struct *dup_mm(struct task_struct *tsk)
1208 struct mm_struct *mm, *oldmm = current->mm;
1215 memcpy(mm, oldmm, sizeof(*mm));
1217 if (!mm_init(mm, tsk, mm->user_ns))
1220 err = dup_mmap(mm, oldmm);
1224 mm->hiwater_rss = get_mm_rss(mm);
1225 mm->hiwater_vm = mm->total_vm;
1227 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1233 /* don't put binfmt in mmput, we haven't got module yet */
1241 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1243 struct mm_struct *mm, *oldmm;
1246 tsk->min_flt = tsk->maj_flt = 0;
1247 tsk->nvcsw = tsk->nivcsw = 0;
1248 #ifdef CONFIG_DETECT_HUNG_TASK
1249 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1253 tsk->active_mm = NULL;
1256 * Are we cloning a kernel thread?
1258 * We need to steal a active VM for that..
1260 oldmm = current->mm;
1264 /* initialize the new vmacache entries */
1265 vmacache_flush(tsk);
1267 if (clone_flags & CLONE_VM) {
1280 tsk->active_mm = mm;
1287 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1289 struct fs_struct *fs = current->fs;
1290 if (clone_flags & CLONE_FS) {
1291 /* tsk->fs is already what we want */
1292 spin_lock(&fs->lock);
1294 spin_unlock(&fs->lock);
1298 spin_unlock(&fs->lock);
1301 tsk->fs = copy_fs_struct(fs);
1307 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1309 struct files_struct *oldf, *newf;
1313 * A background process may not have any files ...
1315 oldf = current->files;
1319 if (clone_flags & CLONE_FILES) {
1320 atomic_inc(&oldf->count);
1324 newf = dup_fd(oldf, &error);
1334 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
1337 struct io_context *ioc = current->io_context;
1338 struct io_context *new_ioc;
1343 * Share io context with parent, if CLONE_IO is set
1345 if (clone_flags & CLONE_IO) {
1347 tsk->io_context = ioc;
1348 } else if (ioprio_valid(ioc->ioprio)) {
1349 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
1350 if (unlikely(!new_ioc))
1353 new_ioc->ioprio = ioc->ioprio;
1354 put_io_context(new_ioc);
1360 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1362 struct sighand_struct *sig;
1364 if (clone_flags & CLONE_SIGHAND) {
1365 atomic_inc(¤t->sighand->count);
1368 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1369 rcu_assign_pointer(tsk->sighand, sig);
1373 atomic_set(&sig->count, 1);
1374 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1378 void __cleanup_sighand(struct sighand_struct *sighand)
1380 if (atomic_dec_and_test(&sighand->count)) {
1381 signalfd_cleanup(sighand);
1383 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1384 * without an RCU grace period, see __lock_task_sighand().
1386 kmem_cache_free(sighand_cachep, sighand);
1390 #ifdef CONFIG_POSIX_TIMERS
1392 * Initialize POSIX timer handling for a thread group.
1394 static void posix_cpu_timers_init_group(struct signal_struct *sig)
1396 unsigned long cpu_limit;
1398 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1399 if (cpu_limit != RLIM_INFINITY) {
1400 sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
1401 sig->cputimer.running = true;
1404 /* The timer lists. */
1405 INIT_LIST_HEAD(&sig->cpu_timers[0]);
1406 INIT_LIST_HEAD(&sig->cpu_timers[1]);
1407 INIT_LIST_HEAD(&sig->cpu_timers[2]);
1410 static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
1413 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1415 struct signal_struct *sig;
1417 if (clone_flags & CLONE_THREAD)
1420 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1425 sig->nr_threads = 1;
1426 atomic_set(&sig->live, 1);
1427 atomic_set(&sig->sigcnt, 1);
1429 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1430 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1431 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1433 init_waitqueue_head(&sig->wait_chldexit);
1434 sig->curr_target = tsk;
1435 init_sigpending(&sig->shared_pending);
1436 seqlock_init(&sig->stats_lock);
1437 prev_cputime_init(&sig->prev_cputime);
1439 #ifdef CONFIG_POSIX_TIMERS
1440 INIT_LIST_HEAD(&sig->posix_timers);
1441 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1442 sig->real_timer.function = it_real_fn;
1445 task_lock(current->group_leader);
1446 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1447 task_unlock(current->group_leader);
1449 posix_cpu_timers_init_group(sig);
1451 tty_audit_fork(sig);
1452 sched_autogroup_fork(sig);
1454 sig->oom_score_adj = current->signal->oom_score_adj;
1455 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1457 mutex_init(&sig->cred_guard_mutex);
1462 static void copy_seccomp(struct task_struct *p)
1464 #ifdef CONFIG_SECCOMP
1466 * Must be called with sighand->lock held, which is common to
1467 * all threads in the group. Holding cred_guard_mutex is not
1468 * needed because this new task is not yet running and cannot
1471 assert_spin_locked(¤t->sighand->siglock);
1473 /* Ref-count the new filter user, and assign it. */
1474 get_seccomp_filter(current);
1475 p->seccomp = current->seccomp;
1478 * Explicitly enable no_new_privs here in case it got set
1479 * between the task_struct being duplicated and holding the
1480 * sighand lock. The seccomp state and nnp must be in sync.
1482 if (task_no_new_privs(current))
1483 task_set_no_new_privs(p);
1486 * If the parent gained a seccomp mode after copying thread
1487 * flags and between before we held the sighand lock, we have
1488 * to manually enable the seccomp thread flag here.
1490 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1491 set_tsk_thread_flag(p, TIF_SECCOMP);
1495 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1497 current->clear_child_tid = tidptr;
1499 return task_pid_vnr(current);
1502 static void rt_mutex_init_task(struct task_struct *p)
1504 raw_spin_lock_init(&p->pi_lock);
1505 #ifdef CONFIG_RT_MUTEXES
1506 p->pi_waiters = RB_ROOT_CACHED;
1507 p->pi_top_task = NULL;
1508 p->pi_blocked_on = NULL;
1512 #ifdef CONFIG_POSIX_TIMERS
1514 * Initialize POSIX timer handling for a single task.
1516 static void posix_cpu_timers_init(struct task_struct *tsk)
1518 tsk->cputime_expires.prof_exp = 0;
1519 tsk->cputime_expires.virt_exp = 0;
1520 tsk->cputime_expires.sched_exp = 0;
1521 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1522 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1523 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1526 static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
1530 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1532 task->pids[type].pid = pid;
1535 static inline void rcu_copy_process(struct task_struct *p)
1537 #ifdef CONFIG_PREEMPT_RCU
1538 p->rcu_read_lock_nesting = 0;
1539 p->rcu_read_unlock_special.s = 0;
1540 p->rcu_blocked_node = NULL;
1541 INIT_LIST_HEAD(&p->rcu_node_entry);
1542 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1543 #ifdef CONFIG_TASKS_RCU
1544 p->rcu_tasks_holdout = false;
1545 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1546 p->rcu_tasks_idle_cpu = -1;
1547 #endif /* #ifdef CONFIG_TASKS_RCU */
1551 * This creates a new process as a copy of the old one,
1552 * but does not actually start it yet.
1554 * It copies the registers, and all the appropriate
1555 * parts of the process environment (as per the clone
1556 * flags). The actual kick-off is left to the caller.
1558 static __latent_entropy struct task_struct *copy_process(
1559 unsigned long clone_flags,
1560 unsigned long stack_start,
1561 unsigned long stack_size,
1562 int __user *child_tidptr,
1569 struct task_struct *p;
1571 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1572 return ERR_PTR(-EINVAL);
1574 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1575 return ERR_PTR(-EINVAL);
1578 * Thread groups must share signals as well, and detached threads
1579 * can only be started up within the thread group.
1581 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1582 return ERR_PTR(-EINVAL);
1585 * Shared signal handlers imply shared VM. By way of the above,
1586 * thread groups also imply shared VM. Blocking this case allows
1587 * for various simplifications in other code.
1589 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1590 return ERR_PTR(-EINVAL);
1593 * Siblings of global init remain as zombies on exit since they are
1594 * not reaped by their parent (swapper). To solve this and to avoid
1595 * multi-rooted process trees, prevent global and container-inits
1596 * from creating siblings.
1598 if ((clone_flags & CLONE_PARENT) &&
1599 current->signal->flags & SIGNAL_UNKILLABLE)
1600 return ERR_PTR(-EINVAL);
1603 * If the new process will be in a different pid or user namespace
1604 * do not allow it to share a thread group with the forking task.
1606 if (clone_flags & CLONE_THREAD) {
1607 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
1608 (task_active_pid_ns(current) !=
1609 current->nsproxy->pid_ns_for_children))
1610 return ERR_PTR(-EINVAL);
1614 p = dup_task_struct(current, node);
1619 * This _must_ happen before we call free_task(), i.e. before we jump
1620 * to any of the bad_fork_* labels. This is to avoid freeing
1621 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1622 * kernel threads (PF_KTHREAD).
1624 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1626 * Clear TID on mm_release()?
1628 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1630 ftrace_graph_init_task(p);
1632 rt_mutex_init_task(p);
1634 #ifdef CONFIG_PROVE_LOCKING
1635 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1636 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1639 if (atomic_read(&p->real_cred->user->processes) >=
1640 task_rlimit(p, RLIMIT_NPROC)) {
1641 if (p->real_cred->user != INIT_USER &&
1642 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
1645 current->flags &= ~PF_NPROC_EXCEEDED;
1647 retval = copy_creds(p, clone_flags);
1652 * If multiple threads are within copy_process(), then this check
1653 * triggers too late. This doesn't hurt, the check is only there
1654 * to stop root fork bombs.
1657 if (nr_threads >= max_threads)
1658 goto bad_fork_cleanup_count;
1660 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1661 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE);
1662 p->flags |= PF_FORKNOEXEC;
1663 INIT_LIST_HEAD(&p->children);
1664 INIT_LIST_HEAD(&p->sibling);
1665 rcu_copy_process(p);
1666 p->vfork_done = NULL;
1667 spin_lock_init(&p->alloc_lock);
1669 init_sigpending(&p->pending);
1671 p->utime = p->stime = p->gtime = 0;
1672 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1673 p->utimescaled = p->stimescaled = 0;
1675 prev_cputime_init(&p->prev_cputime);
1677 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1678 seqcount_init(&p->vtime.seqcount);
1679 p->vtime.starttime = 0;
1680 p->vtime.state = VTIME_INACTIVE;
1683 #if defined(SPLIT_RSS_COUNTING)
1684 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1687 p->default_timer_slack_ns = current->timer_slack_ns;
1689 task_io_accounting_init(&p->ioac);
1690 acct_clear_integrals(p);
1692 posix_cpu_timers_init(p);
1694 p->start_time = ktime_get_ns();
1695 p->real_start_time = ktime_get_boot_ns();
1696 p->io_context = NULL;
1697 p->audit_context = NULL;
1700 p->mempolicy = mpol_dup(p->mempolicy);
1701 if (IS_ERR(p->mempolicy)) {
1702 retval = PTR_ERR(p->mempolicy);
1703 p->mempolicy = NULL;
1704 goto bad_fork_cleanup_threadgroup_lock;
1707 #ifdef CONFIG_CPUSETS
1708 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1709 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1710 seqcount_init(&p->mems_allowed_seq);
1712 #ifdef CONFIG_TRACE_IRQFLAGS
1714 p->hardirqs_enabled = 0;
1715 p->hardirq_enable_ip = 0;
1716 p->hardirq_enable_event = 0;
1717 p->hardirq_disable_ip = _THIS_IP_;
1718 p->hardirq_disable_event = 0;
1719 p->softirqs_enabled = 1;
1720 p->softirq_enable_ip = _THIS_IP_;
1721 p->softirq_enable_event = 0;
1722 p->softirq_disable_ip = 0;
1723 p->softirq_disable_event = 0;
1724 p->hardirq_context = 0;
1725 p->softirq_context = 0;
1728 p->pagefault_disabled = 0;
1730 #ifdef CONFIG_LOCKDEP
1731 p->lockdep_depth = 0; /* no locks held yet */
1732 p->curr_chain_key = 0;
1733 p->lockdep_recursion = 0;
1734 lockdep_init_task(p);
1737 #ifdef CONFIG_DEBUG_MUTEXES
1738 p->blocked_on = NULL; /* not blocked yet */
1740 #ifdef CONFIG_BCACHE
1741 p->sequential_io = 0;
1742 p->sequential_io_avg = 0;
1745 /* Perform scheduler related setup. Assign this task to a CPU. */
1746 retval = sched_fork(clone_flags, p);
1748 goto bad_fork_cleanup_policy;
1750 retval = perf_event_init_task(p);
1752 goto bad_fork_cleanup_policy;
1753 retval = audit_alloc(p);
1755 goto bad_fork_cleanup_perf;
1756 /* copy all the process information */
1758 retval = security_task_alloc(p, clone_flags);
1760 goto bad_fork_cleanup_audit;
1761 retval = copy_semundo(clone_flags, p);
1763 goto bad_fork_cleanup_security;
1764 retval = copy_files(clone_flags, p);
1766 goto bad_fork_cleanup_semundo;
1767 retval = copy_fs(clone_flags, p);
1769 goto bad_fork_cleanup_files;
1770 retval = copy_sighand(clone_flags, p);
1772 goto bad_fork_cleanup_fs;
1773 retval = copy_signal(clone_flags, p);
1775 goto bad_fork_cleanup_sighand;
1776 retval = copy_mm(clone_flags, p);
1778 goto bad_fork_cleanup_signal;
1779 retval = copy_namespaces(clone_flags, p);
1781 goto bad_fork_cleanup_mm;
1782 retval = copy_io(clone_flags, p);
1784 goto bad_fork_cleanup_namespaces;
1785 retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls);
1787 goto bad_fork_cleanup_io;
1789 if (pid != &init_struct_pid) {
1790 pid = alloc_pid(p->nsproxy->pid_ns_for_children);
1792 retval = PTR_ERR(pid);
1793 goto bad_fork_cleanup_thread;
1801 p->robust_list = NULL;
1802 #ifdef CONFIG_COMPAT
1803 p->compat_robust_list = NULL;
1805 INIT_LIST_HEAD(&p->pi_state_list);
1806 p->pi_state_cache = NULL;
1809 * sigaltstack should be cleared when sharing the same VM
1811 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1815 * Syscall tracing and stepping should be turned off in the
1816 * child regardless of CLONE_PTRACE.
1818 user_disable_single_step(p);
1819 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1820 #ifdef TIF_SYSCALL_EMU
1821 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1823 clear_all_latency_tracing(p);
1825 /* ok, now we should be set up.. */
1826 p->pid = pid_nr(pid);
1827 if (clone_flags & CLONE_THREAD) {
1828 p->exit_signal = -1;
1829 p->group_leader = current->group_leader;
1830 p->tgid = current->tgid;
1832 if (clone_flags & CLONE_PARENT)
1833 p->exit_signal = current->group_leader->exit_signal;
1835 p->exit_signal = (clone_flags & CSIGNAL);
1836 p->group_leader = p;
1841 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1842 p->dirty_paused_when = 0;
1844 p->pdeath_signal = 0;
1845 INIT_LIST_HEAD(&p->thread_group);
1846 p->task_works = NULL;
1848 cgroup_threadgroup_change_begin(current);
1850 * Ensure that the cgroup subsystem policies allow the new process to be
1851 * forked. It should be noted the the new process's css_set can be changed
1852 * between here and cgroup_post_fork() if an organisation operation is in
1855 retval = cgroup_can_fork(p);
1857 goto bad_fork_free_pid;
1860 * Make it visible to the rest of the system, but dont wake it up yet.
1861 * Need tasklist lock for parent etc handling!
1863 write_lock_irq(&tasklist_lock);
1865 /* CLONE_PARENT re-uses the old parent */
1866 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
1867 p->real_parent = current->real_parent;
1868 p->parent_exec_id = current->parent_exec_id;
1870 p->real_parent = current;
1871 p->parent_exec_id = current->self_exec_id;
1874 klp_copy_process(p);
1876 spin_lock(¤t->sighand->siglock);
1879 * Copy seccomp details explicitly here, in case they were changed
1880 * before holding sighand lock.
1885 * Process group and session signals need to be delivered to just the
1886 * parent before the fork or both the parent and the child after the
1887 * fork. Restart if a signal comes in before we add the new process to
1888 * it's process group.
1889 * A fatal signal pending means that current will exit, so the new
1890 * thread can't slip out of an OOM kill (or normal SIGKILL).
1892 recalc_sigpending();
1893 if (signal_pending(current)) {
1894 retval = -ERESTARTNOINTR;
1895 goto bad_fork_cancel_cgroup;
1897 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
1899 goto bad_fork_cancel_cgroup;
1902 if (likely(p->pid)) {
1903 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
1905 init_task_pid(p, PIDTYPE_PID, pid);
1906 if (thread_group_leader(p)) {
1907 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
1908 init_task_pid(p, PIDTYPE_SID, task_session(current));
1910 if (is_child_reaper(pid)) {
1911 ns_of_pid(pid)->child_reaper = p;
1912 p->signal->flags |= SIGNAL_UNKILLABLE;
1915 p->signal->leader_pid = pid;
1916 p->signal->tty = tty_kref_get(current->signal->tty);
1918 * Inherit has_child_subreaper flag under the same
1919 * tasklist_lock with adding child to the process tree
1920 * for propagate_has_child_subreaper optimization.
1922 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
1923 p->real_parent->signal->is_child_subreaper;
1924 list_add_tail(&p->sibling, &p->real_parent->children);
1925 list_add_tail_rcu(&p->tasks, &init_task.tasks);
1926 attach_pid(p, PIDTYPE_PGID);
1927 attach_pid(p, PIDTYPE_SID);
1928 __this_cpu_inc(process_counts);
1930 current->signal->nr_threads++;
1931 atomic_inc(¤t->signal->live);
1932 atomic_inc(¤t->signal->sigcnt);
1933 list_add_tail_rcu(&p->thread_group,
1934 &p->group_leader->thread_group);
1935 list_add_tail_rcu(&p->thread_node,
1936 &p->signal->thread_head);
1938 attach_pid(p, PIDTYPE_PID);
1943 spin_unlock(¤t->sighand->siglock);
1944 syscall_tracepoint_update(p);
1945 write_unlock_irq(&tasklist_lock);
1947 proc_fork_connector(p);
1948 cgroup_post_fork(p);
1949 cgroup_threadgroup_change_end(current);
1952 trace_task_newtask(p, clone_flags);
1953 uprobe_copy_process(p, clone_flags);
1957 bad_fork_cancel_cgroup:
1958 spin_unlock(¤t->sighand->siglock);
1959 write_unlock_irq(&tasklist_lock);
1960 cgroup_cancel_fork(p);
1962 cgroup_threadgroup_change_end(current);
1963 if (pid != &init_struct_pid)
1965 bad_fork_cleanup_thread:
1967 bad_fork_cleanup_io:
1970 bad_fork_cleanup_namespaces:
1971 exit_task_namespaces(p);
1972 bad_fork_cleanup_mm:
1975 bad_fork_cleanup_signal:
1976 if (!(clone_flags & CLONE_THREAD))
1977 free_signal_struct(p->signal);
1978 bad_fork_cleanup_sighand:
1979 __cleanup_sighand(p->sighand);
1980 bad_fork_cleanup_fs:
1981 exit_fs(p); /* blocking */
1982 bad_fork_cleanup_files:
1983 exit_files(p); /* blocking */
1984 bad_fork_cleanup_semundo:
1986 bad_fork_cleanup_security:
1987 security_task_free(p);
1988 bad_fork_cleanup_audit:
1990 bad_fork_cleanup_perf:
1991 perf_event_free_task(p);
1992 bad_fork_cleanup_policy:
1993 lockdep_free_task(p);
1995 mpol_put(p->mempolicy);
1996 bad_fork_cleanup_threadgroup_lock:
1998 delayacct_tsk_free(p);
1999 bad_fork_cleanup_count:
2000 atomic_dec(&p->cred->user->processes);
2003 p->state = TASK_DEAD;
2007 return ERR_PTR(retval);
2010 static inline void init_idle_pids(struct pid_link *links)
2014 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2015 INIT_HLIST_NODE(&links[type].node); /* not really needed */
2016 links[type].pid = &init_struct_pid;
2020 struct task_struct *fork_idle(int cpu)
2022 struct task_struct *task;
2023 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0,
2025 if (!IS_ERR(task)) {
2026 init_idle_pids(task->pids);
2027 init_idle(task, cpu);
2034 * Ok, this is the main fork-routine.
2036 * It copies the process, and if successful kick-starts
2037 * it and waits for it to finish using the VM if required.
2039 long _do_fork(unsigned long clone_flags,
2040 unsigned long stack_start,
2041 unsigned long stack_size,
2042 int __user *parent_tidptr,
2043 int __user *child_tidptr,
2046 struct task_struct *p;
2051 * Determine whether and which event to report to ptracer. When
2052 * called from kernel_thread or CLONE_UNTRACED is explicitly
2053 * requested, no event is reported; otherwise, report if the event
2054 * for the type of forking is enabled.
2056 if (!(clone_flags & CLONE_UNTRACED)) {
2057 if (clone_flags & CLONE_VFORK)
2058 trace = PTRACE_EVENT_VFORK;
2059 else if ((clone_flags & CSIGNAL) != SIGCHLD)
2060 trace = PTRACE_EVENT_CLONE;
2062 trace = PTRACE_EVENT_FORK;
2064 if (likely(!ptrace_event_enabled(current, trace)))
2068 p = copy_process(clone_flags, stack_start, stack_size,
2069 child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
2070 add_latent_entropy();
2072 * Do this prior waking up the new thread - the thread pointer
2073 * might get invalid after that point, if the thread exits quickly.
2076 struct completion vfork;
2079 trace_sched_process_fork(current, p);
2081 pid = get_task_pid(p, PIDTYPE_PID);
2084 if (clone_flags & CLONE_PARENT_SETTID)
2085 put_user(nr, parent_tidptr);
2087 if (clone_flags & CLONE_VFORK) {
2088 p->vfork_done = &vfork;
2089 init_completion(&vfork);
2093 wake_up_new_task(p);
2095 /* forking complete and child started to run, tell ptracer */
2096 if (unlikely(trace))
2097 ptrace_event_pid(trace, pid);
2099 if (clone_flags & CLONE_VFORK) {
2100 if (!wait_for_vfork_done(p, &vfork))
2101 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2111 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2112 /* For compatibility with architectures that call do_fork directly rather than
2113 * using the syscall entry points below. */
2114 long do_fork(unsigned long clone_flags,
2115 unsigned long stack_start,
2116 unsigned long stack_size,
2117 int __user *parent_tidptr,
2118 int __user *child_tidptr)
2120 return _do_fork(clone_flags, stack_start, stack_size,
2121 parent_tidptr, child_tidptr, 0);
2126 * Create a kernel thread.
2128 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2130 return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
2131 (unsigned long)arg, NULL, NULL, 0);
2134 #ifdef __ARCH_WANT_SYS_FORK
2135 SYSCALL_DEFINE0(fork)
2138 return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0);
2140 /* can not support in nommu mode */
2146 #ifdef __ARCH_WANT_SYS_VFORK
2147 SYSCALL_DEFINE0(vfork)
2149 return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
2154 #ifdef __ARCH_WANT_SYS_CLONE
2155 #ifdef CONFIG_CLONE_BACKWARDS
2156 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2157 int __user *, parent_tidptr,
2159 int __user *, child_tidptr)
2160 #elif defined(CONFIG_CLONE_BACKWARDS2)
2161 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2162 int __user *, parent_tidptr,
2163 int __user *, child_tidptr,
2165 #elif defined(CONFIG_CLONE_BACKWARDS3)
2166 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2168 int __user *, parent_tidptr,
2169 int __user *, child_tidptr,
2172 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2173 int __user *, parent_tidptr,
2174 int __user *, child_tidptr,
2178 return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
2182 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2184 struct task_struct *leader, *parent, *child;
2187 read_lock(&tasklist_lock);
2188 leader = top = top->group_leader;
2190 for_each_thread(leader, parent) {
2191 list_for_each_entry(child, &parent->children, sibling) {
2192 res = visitor(child, data);
2204 if (leader != top) {
2206 parent = child->real_parent;
2207 leader = parent->group_leader;
2211 read_unlock(&tasklist_lock);
2214 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2215 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2218 static void sighand_ctor(void *data)
2220 struct sighand_struct *sighand = data;
2222 spin_lock_init(&sighand->siglock);
2223 init_waitqueue_head(&sighand->signalfd_wqh);
2226 void __init proc_caches_init(void)
2228 sighand_cachep = kmem_cache_create("sighand_cache",
2229 sizeof(struct sighand_struct), 0,
2230 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2231 SLAB_ACCOUNT, sighand_ctor);
2232 signal_cachep = kmem_cache_create("signal_cache",
2233 sizeof(struct signal_struct), 0,
2234 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2236 files_cachep = kmem_cache_create("files_cache",
2237 sizeof(struct files_struct), 0,
2238 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2240 fs_cachep = kmem_cache_create("fs_cache",
2241 sizeof(struct fs_struct), 0,
2242 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2245 * FIXME! The "sizeof(struct mm_struct)" currently includes the
2246 * whole struct cpumask for the OFFSTACK case. We could change
2247 * this to *only* allocate as much of it as required by the
2248 * maximum number of CPU's we can ever have. The cpumask_allocation
2249 * is at the end of the structure, exactly for that reason.
2251 mm_cachep = kmem_cache_create("mm_struct",
2252 sizeof(struct mm_struct), ARCH_MIN_MMSTRUCT_ALIGN,
2253 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2255 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
2257 nsproxy_cache_init();
2261 * Check constraints on flags passed to the unshare system call.
2263 static int check_unshare_flags(unsigned long unshare_flags)
2265 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
2266 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
2267 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
2268 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP))
2271 * Not implemented, but pretend it works if there is nothing
2272 * to unshare. Note that unsharing the address space or the
2273 * signal handlers also need to unshare the signal queues (aka
2276 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
2277 if (!thread_group_empty(current))
2280 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
2281 if (atomic_read(¤t->sighand->count) > 1)
2284 if (unshare_flags & CLONE_VM) {
2285 if (!current_is_single_threaded())
2293 * Unshare the filesystem structure if it is being shared
2295 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
2297 struct fs_struct *fs = current->fs;
2299 if (!(unshare_flags & CLONE_FS) || !fs)
2302 /* don't need lock here; in the worst case we'll do useless copy */
2306 *new_fsp = copy_fs_struct(fs);
2314 * Unshare file descriptor table if it is being shared
2316 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
2318 struct files_struct *fd = current->files;
2321 if ((unshare_flags & CLONE_FILES) &&
2322 (fd && atomic_read(&fd->count) > 1)) {
2323 *new_fdp = dup_fd(fd, &error);
2332 * unshare allows a process to 'unshare' part of the process
2333 * context which was originally shared using clone. copy_*
2334 * functions used by do_fork() cannot be used here directly
2335 * because they modify an inactive task_struct that is being
2336 * constructed. Here we are modifying the current, active,
2339 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
2341 struct fs_struct *fs, *new_fs = NULL;
2342 struct files_struct *fd, *new_fd = NULL;
2343 struct cred *new_cred = NULL;
2344 struct nsproxy *new_nsproxy = NULL;
2349 * If unsharing a user namespace must also unshare the thread group
2350 * and unshare the filesystem root and working directories.
2352 if (unshare_flags & CLONE_NEWUSER)
2353 unshare_flags |= CLONE_THREAD | CLONE_FS;
2355 * If unsharing vm, must also unshare signal handlers.
2357 if (unshare_flags & CLONE_VM)
2358 unshare_flags |= CLONE_SIGHAND;
2360 * If unsharing a signal handlers, must also unshare the signal queues.
2362 if (unshare_flags & CLONE_SIGHAND)
2363 unshare_flags |= CLONE_THREAD;
2365 * If unsharing namespace, must also unshare filesystem information.
2367 if (unshare_flags & CLONE_NEWNS)
2368 unshare_flags |= CLONE_FS;
2370 err = check_unshare_flags(unshare_flags);
2372 goto bad_unshare_out;
2374 * CLONE_NEWIPC must also detach from the undolist: after switching
2375 * to a new ipc namespace, the semaphore arrays from the old
2376 * namespace are unreachable.
2378 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
2380 err = unshare_fs(unshare_flags, &new_fs);
2382 goto bad_unshare_out;
2383 err = unshare_fd(unshare_flags, &new_fd);
2385 goto bad_unshare_cleanup_fs;
2386 err = unshare_userns(unshare_flags, &new_cred);
2388 goto bad_unshare_cleanup_fd;
2389 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
2392 goto bad_unshare_cleanup_cred;
2394 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
2397 * CLONE_SYSVSEM is equivalent to sys_exit().
2401 if (unshare_flags & CLONE_NEWIPC) {
2402 /* Orphan segments in old ns (see sem above). */
2404 shm_init_task(current);
2408 switch_task_namespaces(current, new_nsproxy);
2414 spin_lock(&fs->lock);
2415 current->fs = new_fs;
2420 spin_unlock(&fs->lock);
2424 fd = current->files;
2425 current->files = new_fd;
2429 task_unlock(current);
2432 /* Install the new user namespace */
2433 commit_creds(new_cred);
2438 perf_event_namespaces(current);
2440 bad_unshare_cleanup_cred:
2443 bad_unshare_cleanup_fd:
2445 put_files_struct(new_fd);
2447 bad_unshare_cleanup_fs:
2449 free_fs_struct(new_fs);
2456 * Helper to unshare the files of the current task.
2457 * We don't want to expose copy_files internals to
2458 * the exec layer of the kernel.
2461 int unshare_files(struct files_struct **displaced)
2463 struct task_struct *task = current;
2464 struct files_struct *copy = NULL;
2467 error = unshare_fd(CLONE_FILES, ©);
2468 if (error || !copy) {
2472 *displaced = task->files;
2479 int sysctl_max_threads(struct ctl_table *table, int write,
2480 void __user *buffer, size_t *lenp, loff_t *ppos)
2484 int threads = max_threads;
2485 int min = MIN_THREADS;
2486 int max = MAX_THREADS;
2493 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2497 set_max_threads(threads);