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 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
169 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
170 * kmemcache based allocator.
172 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
174 #ifdef CONFIG_VMAP_STACK
176 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
177 * flush. Try to minimize the number of calls by caching stacks.
179 #define NR_CACHED_STACKS 2
180 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
182 static int free_vm_stack_cache(unsigned int cpu)
184 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
187 for (i = 0; i < NR_CACHED_STACKS; i++) {
188 struct vm_struct *vm_stack = cached_vm_stacks[i];
193 vfree(vm_stack->addr);
194 cached_vm_stacks[i] = NULL;
201 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
203 #ifdef CONFIG_VMAP_STACK
207 for (i = 0; i < NR_CACHED_STACKS; i++) {
210 s = this_cpu_xchg(cached_stacks[i], NULL);
215 /* Clear stale pointers from reused stack. */
216 memset(s->addr, 0, THREAD_SIZE);
218 tsk->stack_vm_area = s;
219 tsk->stack = s->addr;
223 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
224 VMALLOC_START, VMALLOC_END,
227 0, node, __builtin_return_address(0));
230 * We can't call find_vm_area() in interrupt context, and
231 * free_thread_stack() can be called in interrupt context,
232 * so cache the vm_struct.
235 tsk->stack_vm_area = find_vm_area(stack);
240 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
244 tsk->stack = page_address(page);
251 static inline void free_thread_stack(struct task_struct *tsk)
253 #ifdef CONFIG_VMAP_STACK
254 if (task_stack_vm_area(tsk)) {
257 for (i = 0; i < NR_CACHED_STACKS; i++) {
258 if (this_cpu_cmpxchg(cached_stacks[i],
259 NULL, tsk->stack_vm_area) != NULL)
265 vfree_atomic(tsk->stack);
270 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
273 static struct kmem_cache *thread_stack_cache;
275 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
278 unsigned long *stack;
279 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
284 static void free_thread_stack(struct task_struct *tsk)
286 kmem_cache_free(thread_stack_cache, tsk->stack);
289 void thread_stack_cache_init(void)
291 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
292 THREAD_SIZE, THREAD_SIZE, 0, 0,
294 BUG_ON(thread_stack_cache == NULL);
299 /* SLAB cache for signal_struct structures (tsk->signal) */
300 static struct kmem_cache *signal_cachep;
302 /* SLAB cache for sighand_struct structures (tsk->sighand) */
303 struct kmem_cache *sighand_cachep;
305 /* SLAB cache for files_struct structures (tsk->files) */
306 struct kmem_cache *files_cachep;
308 /* SLAB cache for fs_struct structures (tsk->fs) */
309 struct kmem_cache *fs_cachep;
311 /* SLAB cache for vm_area_struct structures */
312 static struct kmem_cache *vm_area_cachep;
314 /* SLAB cache for mm_struct structures (tsk->mm) */
315 static struct kmem_cache *mm_cachep;
317 struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
319 struct vm_area_struct *vma;
321 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
327 struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
329 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
333 INIT_LIST_HEAD(&new->anon_vma_chain);
338 void vm_area_free(struct vm_area_struct *vma)
340 kmem_cache_free(vm_area_cachep, vma);
343 static void account_kernel_stack(struct task_struct *tsk, int account)
345 void *stack = task_stack_page(tsk);
346 struct vm_struct *vm = task_stack_vm_area(tsk);
348 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
353 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
355 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
356 mod_zone_page_state(page_zone(vm->pages[i]),
358 PAGE_SIZE / 1024 * account);
361 /* All stack pages belong to the same memcg. */
362 mod_memcg_page_state(vm->pages[0], MEMCG_KERNEL_STACK_KB,
363 account * (THREAD_SIZE / 1024));
366 * All stack pages are in the same zone and belong to the
369 struct page *first_page = virt_to_page(stack);
371 mod_zone_page_state(page_zone(first_page), NR_KERNEL_STACK_KB,
372 THREAD_SIZE / 1024 * account);
374 mod_memcg_page_state(first_page, MEMCG_KERNEL_STACK_KB,
375 account * (THREAD_SIZE / 1024));
379 static void release_task_stack(struct task_struct *tsk)
381 if (WARN_ON(tsk->state != TASK_DEAD))
382 return; /* Better to leak the stack than to free prematurely */
384 account_kernel_stack(tsk, -1);
385 free_thread_stack(tsk);
387 #ifdef CONFIG_VMAP_STACK
388 tsk->stack_vm_area = NULL;
392 #ifdef CONFIG_THREAD_INFO_IN_TASK
393 void put_task_stack(struct task_struct *tsk)
395 if (atomic_dec_and_test(&tsk->stack_refcount))
396 release_task_stack(tsk);
400 void free_task(struct task_struct *tsk)
402 #ifndef CONFIG_THREAD_INFO_IN_TASK
404 * The task is finally done with both the stack and thread_info,
407 release_task_stack(tsk);
410 * If the task had a separate stack allocation, it should be gone
413 WARN_ON_ONCE(atomic_read(&tsk->stack_refcount) != 0);
415 rt_mutex_debug_task_free(tsk);
416 ftrace_graph_exit_task(tsk);
417 put_seccomp_filter(tsk);
418 arch_release_task_struct(tsk);
419 if (tsk->flags & PF_KTHREAD)
420 free_kthread_struct(tsk);
421 free_task_struct(tsk);
423 EXPORT_SYMBOL(free_task);
426 static __latent_entropy int dup_mmap(struct mm_struct *mm,
427 struct mm_struct *oldmm)
429 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
430 struct rb_node **rb_link, *rb_parent;
432 unsigned long charge;
435 uprobe_start_dup_mmap();
436 if (down_write_killable(&oldmm->mmap_sem)) {
438 goto fail_uprobe_end;
440 flush_cache_dup_mm(oldmm);
441 uprobe_dup_mmap(oldmm, mm);
443 * Not linked in yet - no deadlock potential:
445 down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
447 /* No ordering required: file already has been exposed. */
448 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
450 mm->total_vm = oldmm->total_vm;
451 mm->data_vm = oldmm->data_vm;
452 mm->exec_vm = oldmm->exec_vm;
453 mm->stack_vm = oldmm->stack_vm;
455 rb_link = &mm->mm_rb.rb_node;
458 retval = ksm_fork(mm, oldmm);
461 retval = khugepaged_fork(mm, oldmm);
466 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
469 if (mpnt->vm_flags & VM_DONTCOPY) {
470 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
475 * Don't duplicate many vmas if we've been oom-killed (for
478 if (fatal_signal_pending(current)) {
482 if (mpnt->vm_flags & VM_ACCOUNT) {
483 unsigned long len = vma_pages(mpnt);
485 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
489 tmp = vm_area_dup(mpnt);
492 retval = vma_dup_policy(mpnt, tmp);
494 goto fail_nomem_policy;
496 retval = dup_userfaultfd(tmp, &uf);
498 goto fail_nomem_anon_vma_fork;
499 if (tmp->vm_flags & VM_WIPEONFORK) {
500 /* VM_WIPEONFORK gets a clean slate in the child. */
501 tmp->anon_vma = NULL;
502 if (anon_vma_prepare(tmp))
503 goto fail_nomem_anon_vma_fork;
504 } else if (anon_vma_fork(tmp, mpnt))
505 goto fail_nomem_anon_vma_fork;
506 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
507 tmp->vm_next = tmp->vm_prev = NULL;
510 struct inode *inode = file_inode(file);
511 struct address_space *mapping = file->f_mapping;
514 if (tmp->vm_flags & VM_DENYWRITE)
515 atomic_dec(&inode->i_writecount);
516 i_mmap_lock_write(mapping);
517 if (tmp->vm_flags & VM_SHARED)
518 atomic_inc(&mapping->i_mmap_writable);
519 flush_dcache_mmap_lock(mapping);
520 /* insert tmp into the share list, just after mpnt */
521 vma_interval_tree_insert_after(tmp, mpnt,
523 flush_dcache_mmap_unlock(mapping);
524 i_mmap_unlock_write(mapping);
528 * Clear hugetlb-related page reserves for children. This only
529 * affects MAP_PRIVATE mappings. Faults generated by the child
530 * are not guaranteed to succeed, even if read-only
532 if (is_vm_hugetlb_page(tmp))
533 reset_vma_resv_huge_pages(tmp);
536 * Link in the new vma and copy the page table entries.
539 pprev = &tmp->vm_next;
543 __vma_link_rb(mm, tmp, rb_link, rb_parent);
544 rb_link = &tmp->vm_rb.rb_right;
545 rb_parent = &tmp->vm_rb;
548 if (!(tmp->vm_flags & VM_WIPEONFORK))
549 retval = copy_page_range(mm, oldmm, mpnt);
551 if (tmp->vm_ops && tmp->vm_ops->open)
552 tmp->vm_ops->open(tmp);
557 /* a new mm has just been created */
558 retval = arch_dup_mmap(oldmm, mm);
560 up_write(&mm->mmap_sem);
562 up_write(&oldmm->mmap_sem);
563 dup_userfaultfd_complete(&uf);
565 uprobe_end_dup_mmap();
567 fail_nomem_anon_vma_fork:
568 mpol_put(vma_policy(tmp));
573 vm_unacct_memory(charge);
577 static inline int mm_alloc_pgd(struct mm_struct *mm)
579 mm->pgd = pgd_alloc(mm);
580 if (unlikely(!mm->pgd))
585 static inline void mm_free_pgd(struct mm_struct *mm)
587 pgd_free(mm, mm->pgd);
590 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
592 down_write(&oldmm->mmap_sem);
593 RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
594 up_write(&oldmm->mmap_sem);
597 #define mm_alloc_pgd(mm) (0)
598 #define mm_free_pgd(mm)
599 #endif /* CONFIG_MMU */
601 static void check_mm(struct mm_struct *mm)
605 for (i = 0; i < NR_MM_COUNTERS; i++) {
606 long x = atomic_long_read(&mm->rss_stat.count[i]);
609 printk(KERN_ALERT "BUG: Bad rss-counter state "
610 "mm:%p idx:%d val:%ld\n", mm, i, x);
613 if (mm_pgtables_bytes(mm))
614 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
615 mm_pgtables_bytes(mm));
617 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
618 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
622 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
623 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
626 * Called when the last reference to the mm
627 * is dropped: either by a lazy thread or by
628 * mmput. Free the page directory and the mm.
630 void __mmdrop(struct mm_struct *mm)
632 BUG_ON(mm == &init_mm);
633 WARN_ON_ONCE(mm == current->mm);
634 WARN_ON_ONCE(mm == current->active_mm);
638 mmu_notifier_mm_destroy(mm);
640 put_user_ns(mm->user_ns);
643 EXPORT_SYMBOL_GPL(__mmdrop);
645 static void mmdrop_async_fn(struct work_struct *work)
647 struct mm_struct *mm;
649 mm = container_of(work, struct mm_struct, async_put_work);
653 static void mmdrop_async(struct mm_struct *mm)
655 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
656 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
657 schedule_work(&mm->async_put_work);
661 static inline void free_signal_struct(struct signal_struct *sig)
663 taskstats_tgid_free(sig);
664 sched_autogroup_exit(sig);
666 * __mmdrop is not safe to call from softirq context on x86 due to
667 * pgd_dtor so postpone it to the async context
670 mmdrop_async(sig->oom_mm);
671 kmem_cache_free(signal_cachep, sig);
674 static inline void put_signal_struct(struct signal_struct *sig)
676 if (atomic_dec_and_test(&sig->sigcnt))
677 free_signal_struct(sig);
680 void __put_task_struct(struct task_struct *tsk)
682 WARN_ON(!tsk->exit_state);
683 WARN_ON(atomic_read(&tsk->usage));
684 WARN_ON(tsk == current);
687 task_numa_free(tsk, true);
688 security_task_free(tsk);
690 delayacct_tsk_free(tsk);
691 put_signal_struct(tsk->signal);
693 if (!profile_handoff_task(tsk))
696 EXPORT_SYMBOL_GPL(__put_task_struct);
698 void __init __weak arch_task_cache_init(void) { }
703 static void set_max_threads(unsigned int max_threads_suggested)
708 * The number of threads shall be limited such that the thread
709 * structures may only consume a small part of the available memory.
711 if (fls64(totalram_pages) + fls64(PAGE_SIZE) > 64)
712 threads = MAX_THREADS;
714 threads = div64_u64((u64) totalram_pages * (u64) PAGE_SIZE,
715 (u64) THREAD_SIZE * 8UL);
717 if (threads > max_threads_suggested)
718 threads = max_threads_suggested;
720 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
723 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
724 /* Initialized by the architecture: */
725 int arch_task_struct_size __read_mostly;
728 static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
730 /* Fetch thread_struct whitelist for the architecture. */
731 arch_thread_struct_whitelist(offset, size);
734 * Handle zero-sized whitelist or empty thread_struct, otherwise
735 * adjust offset to position of thread_struct in task_struct.
737 if (unlikely(*size == 0))
740 *offset += offsetof(struct task_struct, thread);
743 void __init fork_init(void)
746 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
747 #ifndef ARCH_MIN_TASKALIGN
748 #define ARCH_MIN_TASKALIGN 0
750 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
751 unsigned long useroffset, usersize;
753 /* create a slab on which task_structs can be allocated */
754 task_struct_whitelist(&useroffset, &usersize);
755 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
756 arch_task_struct_size, align,
757 SLAB_PANIC|SLAB_ACCOUNT,
758 useroffset, usersize, NULL);
761 /* do the arch specific task caches init */
762 arch_task_cache_init();
764 set_max_threads(MAX_THREADS);
766 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
767 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
768 init_task.signal->rlim[RLIMIT_SIGPENDING] =
769 init_task.signal->rlim[RLIMIT_NPROC];
771 for (i = 0; i < UCOUNT_COUNTS; i++) {
772 init_user_ns.ucount_max[i] = max_threads/2;
775 #ifdef CONFIG_VMAP_STACK
776 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
777 NULL, free_vm_stack_cache);
780 lockdep_init_task(&init_task);
783 int __weak arch_dup_task_struct(struct task_struct *dst,
784 struct task_struct *src)
790 void set_task_stack_end_magic(struct task_struct *tsk)
792 unsigned long *stackend;
794 stackend = end_of_stack(tsk);
795 *stackend = STACK_END_MAGIC; /* for overflow detection */
798 static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
800 struct task_struct *tsk;
801 unsigned long *stack;
802 struct vm_struct *stack_vm_area;
805 if (node == NUMA_NO_NODE)
806 node = tsk_fork_get_node(orig);
807 tsk = alloc_task_struct_node(node);
811 stack = alloc_thread_stack_node(tsk, node);
815 stack_vm_area = task_stack_vm_area(tsk);
817 err = arch_dup_task_struct(tsk, orig);
820 * arch_dup_task_struct() clobbers the stack-related fields. Make
821 * sure they're properly initialized before using any stack-related
825 #ifdef CONFIG_VMAP_STACK
826 tsk->stack_vm_area = stack_vm_area;
828 #ifdef CONFIG_THREAD_INFO_IN_TASK
829 atomic_set(&tsk->stack_refcount, 1);
835 #ifdef CONFIG_SECCOMP
837 * We must handle setting up seccomp filters once we're under
838 * the sighand lock in case orig has changed between now and
839 * then. Until then, filter must be NULL to avoid messing up
840 * the usage counts on the error path calling free_task.
842 tsk->seccomp.filter = NULL;
845 setup_thread_stack(tsk, orig);
846 clear_user_return_notifier(tsk);
847 clear_tsk_need_resched(tsk);
848 set_task_stack_end_magic(tsk);
850 #ifdef CONFIG_STACKPROTECTOR
851 tsk->stack_canary = get_random_canary();
855 * One for us, one for whoever does the "release_task()" (usually
858 atomic_set(&tsk->usage, 2);
859 #ifdef CONFIG_BLK_DEV_IO_TRACE
862 tsk->splice_pipe = NULL;
863 tsk->task_frag.page = NULL;
864 tsk->wake_q.next = NULL;
866 account_kernel_stack(tsk, 1);
870 #ifdef CONFIG_FAULT_INJECTION
874 #ifdef CONFIG_BLK_CGROUP
875 tsk->throttle_queue = NULL;
876 tsk->use_memdelay = 0;
880 tsk->active_memcg = NULL;
885 free_thread_stack(tsk);
887 free_task_struct(tsk);
891 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
893 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
895 static int __init coredump_filter_setup(char *s)
897 default_dump_filter =
898 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
899 MMF_DUMP_FILTER_MASK;
903 __setup("coredump_filter=", coredump_filter_setup);
905 #include <linux/init_task.h>
907 static void mm_init_aio(struct mm_struct *mm)
910 spin_lock_init(&mm->ioctx_lock);
911 mm->ioctx_table = NULL;
915 static __always_inline void mm_clear_owner(struct mm_struct *mm,
916 struct task_struct *p)
920 WRITE_ONCE(mm->owner, NULL);
924 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
931 static void mm_init_uprobes_state(struct mm_struct *mm)
933 #ifdef CONFIG_UPROBES
934 mm->uprobes_state.xol_area = NULL;
938 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
939 struct user_namespace *user_ns)
943 mm->vmacache_seqnum = 0;
944 atomic_set(&mm->mm_users, 1);
945 atomic_set(&mm->mm_count, 1);
946 init_rwsem(&mm->mmap_sem);
947 INIT_LIST_HEAD(&mm->mmlist);
948 mm->core_state = NULL;
949 mm_pgtables_bytes_init(mm);
953 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
954 spin_lock_init(&mm->page_table_lock);
955 spin_lock_init(&mm->arg_lock);
958 mm_init_owner(mm, p);
959 RCU_INIT_POINTER(mm->exe_file, NULL);
960 mmu_notifier_mm_init(mm);
962 init_tlb_flush_pending(mm);
963 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
964 mm->pmd_huge_pte = NULL;
966 mm_init_uprobes_state(mm);
967 hugetlb_count_init(mm);
970 mm->flags = current->mm->flags & MMF_INIT_MASK;
971 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
973 mm->flags = default_dump_filter;
977 if (mm_alloc_pgd(mm))
980 if (init_new_context(p, mm))
983 mm->user_ns = get_user_ns(user_ns);
994 * Allocate and initialize an mm_struct.
996 struct mm_struct *mm_alloc(void)
998 struct mm_struct *mm;
1004 memset(mm, 0, sizeof(*mm));
1005 return mm_init(mm, current, current_user_ns());
1008 static inline void __mmput(struct mm_struct *mm)
1010 VM_BUG_ON(atomic_read(&mm->mm_users));
1012 uprobe_clear_state(mm);
1015 khugepaged_exit(mm); /* must run before exit_mmap */
1017 mm_put_huge_zero_page(mm);
1018 set_mm_exe_file(mm, NULL);
1019 if (!list_empty(&mm->mmlist)) {
1020 spin_lock(&mmlist_lock);
1021 list_del(&mm->mmlist);
1022 spin_unlock(&mmlist_lock);
1025 module_put(mm->binfmt->module);
1030 * Decrement the use count and release all resources for an mm.
1032 void mmput(struct mm_struct *mm)
1036 if (atomic_dec_and_test(&mm->mm_users))
1039 EXPORT_SYMBOL_GPL(mmput);
1042 static void mmput_async_fn(struct work_struct *work)
1044 struct mm_struct *mm = container_of(work, struct mm_struct,
1050 void mmput_async(struct mm_struct *mm)
1052 if (atomic_dec_and_test(&mm->mm_users)) {
1053 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1054 schedule_work(&mm->async_put_work);
1060 * set_mm_exe_file - change a reference to the mm's executable file
1062 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1064 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1065 * invocations: in mmput() nobody alive left, in execve task is single
1066 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1067 * mm->exe_file, but does so without using set_mm_exe_file() in order
1068 * to do avoid the need for any locks.
1070 void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1072 struct file *old_exe_file;
1075 * It is safe to dereference the exe_file without RCU as
1076 * this function is only called if nobody else can access
1077 * this mm -- see comment above for justification.
1079 old_exe_file = rcu_dereference_raw(mm->exe_file);
1082 get_file(new_exe_file);
1083 rcu_assign_pointer(mm->exe_file, new_exe_file);
1089 * get_mm_exe_file - acquire a reference to the mm's executable file
1091 * Returns %NULL if mm has no associated executable file.
1092 * User must release file via fput().
1094 struct file *get_mm_exe_file(struct mm_struct *mm)
1096 struct file *exe_file;
1099 exe_file = rcu_dereference(mm->exe_file);
1100 if (exe_file && !get_file_rcu(exe_file))
1105 EXPORT_SYMBOL(get_mm_exe_file);
1108 * get_task_exe_file - acquire a reference to the task's executable file
1110 * Returns %NULL if task's mm (if any) has no associated executable file or
1111 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1112 * User must release file via fput().
1114 struct file *get_task_exe_file(struct task_struct *task)
1116 struct file *exe_file = NULL;
1117 struct mm_struct *mm;
1122 if (!(task->flags & PF_KTHREAD))
1123 exe_file = get_mm_exe_file(mm);
1128 EXPORT_SYMBOL(get_task_exe_file);
1131 * get_task_mm - acquire a reference to the task's mm
1133 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1134 * this kernel workthread has transiently adopted a user mm with use_mm,
1135 * to do its AIO) is not set and if so returns a reference to it, after
1136 * bumping up the use count. User must release the mm via mmput()
1137 * after use. Typically used by /proc and ptrace.
1139 struct mm_struct *get_task_mm(struct task_struct *task)
1141 struct mm_struct *mm;
1146 if (task->flags & PF_KTHREAD)
1154 EXPORT_SYMBOL_GPL(get_task_mm);
1156 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1158 struct mm_struct *mm;
1161 err = mutex_lock_killable(&task->signal->cred_guard_mutex);
1163 return ERR_PTR(err);
1165 mm = get_task_mm(task);
1166 if (mm && mm != current->mm &&
1167 !ptrace_may_access(task, mode)) {
1169 mm = ERR_PTR(-EACCES);
1171 mutex_unlock(&task->signal->cred_guard_mutex);
1176 static void complete_vfork_done(struct task_struct *tsk)
1178 struct completion *vfork;
1181 vfork = tsk->vfork_done;
1182 if (likely(vfork)) {
1183 tsk->vfork_done = NULL;
1189 static int wait_for_vfork_done(struct task_struct *child,
1190 struct completion *vfork)
1194 freezer_do_not_count();
1195 killed = wait_for_completion_killable(vfork);
1200 child->vfork_done = NULL;
1204 put_task_struct(child);
1208 /* Please note the differences between mmput and mm_release.
1209 * mmput is called whenever we stop holding onto a mm_struct,
1210 * error success whatever.
1212 * mm_release is called after a mm_struct has been removed
1213 * from the current process.
1215 * This difference is important for error handling, when we
1216 * only half set up a mm_struct for a new process and need to restore
1217 * the old one. Because we mmput the new mm_struct before
1218 * restoring the old one. . .
1219 * Eric Biederman 10 January 1998
1221 static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1223 uprobe_free_utask(tsk);
1225 /* Get rid of any cached register state */
1226 deactivate_mm(tsk, mm);
1229 * Signal userspace if we're not exiting with a core dump
1230 * because we want to leave the value intact for debugging
1233 if (tsk->clear_child_tid) {
1234 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) &&
1235 atomic_read(&mm->mm_users) > 1) {
1237 * We don't check the error code - if userspace has
1238 * not set up a proper pointer then tough luck.
1240 put_user(0, tsk->clear_child_tid);
1241 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1242 1, NULL, NULL, 0, 0);
1244 tsk->clear_child_tid = NULL;
1248 * All done, finally we can wake up parent and return this mm to him.
1249 * Also kthread_stop() uses this completion for synchronization.
1251 if (tsk->vfork_done)
1252 complete_vfork_done(tsk);
1255 void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1257 futex_exit_release(tsk);
1258 mm_release(tsk, mm);
1261 void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1263 futex_exec_release(tsk);
1264 mm_release(tsk, mm);
1268 * Allocate a new mm structure and copy contents from the
1269 * mm structure of the passed in task structure.
1271 static struct mm_struct *dup_mm(struct task_struct *tsk)
1273 struct mm_struct *mm, *oldmm = current->mm;
1280 memcpy(mm, oldmm, sizeof(*mm));
1282 if (!mm_init(mm, tsk, mm->user_ns))
1285 err = dup_mmap(mm, oldmm);
1289 mm->hiwater_rss = get_mm_rss(mm);
1290 mm->hiwater_vm = mm->total_vm;
1292 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1298 /* don't put binfmt in mmput, we haven't got module yet */
1300 mm_init_owner(mm, NULL);
1307 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1309 struct mm_struct *mm, *oldmm;
1312 tsk->min_flt = tsk->maj_flt = 0;
1313 tsk->nvcsw = tsk->nivcsw = 0;
1314 #ifdef CONFIG_DETECT_HUNG_TASK
1315 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1316 tsk->last_switch_time = 0;
1320 tsk->active_mm = NULL;
1323 * Are we cloning a kernel thread?
1325 * We need to steal a active VM for that..
1327 oldmm = current->mm;
1331 /* initialize the new vmacache entries */
1332 vmacache_flush(tsk);
1334 if (clone_flags & CLONE_VM) {
1347 tsk->active_mm = mm;
1354 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1356 struct fs_struct *fs = current->fs;
1357 if (clone_flags & CLONE_FS) {
1358 /* tsk->fs is already what we want */
1359 spin_lock(&fs->lock);
1361 spin_unlock(&fs->lock);
1365 spin_unlock(&fs->lock);
1368 tsk->fs = copy_fs_struct(fs);
1374 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1376 struct files_struct *oldf, *newf;
1380 * A background process may not have any files ...
1382 oldf = current->files;
1386 if (clone_flags & CLONE_FILES) {
1387 atomic_inc(&oldf->count);
1391 newf = dup_fd(oldf, &error);
1401 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
1404 struct io_context *ioc = current->io_context;
1405 struct io_context *new_ioc;
1410 * Share io context with parent, if CLONE_IO is set
1412 if (clone_flags & CLONE_IO) {
1414 tsk->io_context = ioc;
1415 } else if (ioprio_valid(ioc->ioprio)) {
1416 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
1417 if (unlikely(!new_ioc))
1420 new_ioc->ioprio = ioc->ioprio;
1421 put_io_context(new_ioc);
1427 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1429 struct sighand_struct *sig;
1431 if (clone_flags & CLONE_SIGHAND) {
1432 atomic_inc(¤t->sighand->count);
1435 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1436 rcu_assign_pointer(tsk->sighand, sig);
1440 atomic_set(&sig->count, 1);
1441 spin_lock_irq(¤t->sighand->siglock);
1442 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1443 spin_unlock_irq(¤t->sighand->siglock);
1447 void __cleanup_sighand(struct sighand_struct *sighand)
1449 if (atomic_dec_and_test(&sighand->count)) {
1450 signalfd_cleanup(sighand);
1452 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1453 * without an RCU grace period, see __lock_task_sighand().
1455 kmem_cache_free(sighand_cachep, sighand);
1459 #ifdef CONFIG_POSIX_TIMERS
1461 * Initialize POSIX timer handling for a thread group.
1463 static void posix_cpu_timers_init_group(struct signal_struct *sig)
1465 unsigned long cpu_limit;
1467 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1468 if (cpu_limit != RLIM_INFINITY) {
1469 sig->cputime_expires.prof_exp = cpu_limit * NSEC_PER_SEC;
1470 sig->cputimer.running = true;
1473 /* The timer lists. */
1474 INIT_LIST_HEAD(&sig->cpu_timers[0]);
1475 INIT_LIST_HEAD(&sig->cpu_timers[1]);
1476 INIT_LIST_HEAD(&sig->cpu_timers[2]);
1479 static inline void posix_cpu_timers_init_group(struct signal_struct *sig) { }
1482 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1484 struct signal_struct *sig;
1486 if (clone_flags & CLONE_THREAD)
1489 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1494 sig->nr_threads = 1;
1495 atomic_set(&sig->live, 1);
1496 atomic_set(&sig->sigcnt, 1);
1498 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1499 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1500 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1502 init_waitqueue_head(&sig->wait_chldexit);
1503 sig->curr_target = tsk;
1504 init_sigpending(&sig->shared_pending);
1505 INIT_HLIST_HEAD(&sig->multiprocess);
1506 seqlock_init(&sig->stats_lock);
1507 prev_cputime_init(&sig->prev_cputime);
1509 #ifdef CONFIG_POSIX_TIMERS
1510 INIT_LIST_HEAD(&sig->posix_timers);
1511 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1512 sig->real_timer.function = it_real_fn;
1515 task_lock(current->group_leader);
1516 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1517 task_unlock(current->group_leader);
1519 posix_cpu_timers_init_group(sig);
1521 tty_audit_fork(sig);
1522 sched_autogroup_fork(sig);
1524 sig->oom_score_adj = current->signal->oom_score_adj;
1525 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1527 mutex_init(&sig->cred_guard_mutex);
1532 static void copy_seccomp(struct task_struct *p)
1534 #ifdef CONFIG_SECCOMP
1536 * Must be called with sighand->lock held, which is common to
1537 * all threads in the group. Holding cred_guard_mutex is not
1538 * needed because this new task is not yet running and cannot
1541 assert_spin_locked(¤t->sighand->siglock);
1543 /* Ref-count the new filter user, and assign it. */
1544 get_seccomp_filter(current);
1545 p->seccomp = current->seccomp;
1548 * Explicitly enable no_new_privs here in case it got set
1549 * between the task_struct being duplicated and holding the
1550 * sighand lock. The seccomp state and nnp must be in sync.
1552 if (task_no_new_privs(current))
1553 task_set_no_new_privs(p);
1556 * If the parent gained a seccomp mode after copying thread
1557 * flags and between before we held the sighand lock, we have
1558 * to manually enable the seccomp thread flag here.
1560 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1561 set_tsk_thread_flag(p, TIF_SECCOMP);
1565 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1567 current->clear_child_tid = tidptr;
1569 return task_pid_vnr(current);
1572 static void rt_mutex_init_task(struct task_struct *p)
1574 raw_spin_lock_init(&p->pi_lock);
1575 #ifdef CONFIG_RT_MUTEXES
1576 p->pi_waiters = RB_ROOT_CACHED;
1577 p->pi_top_task = NULL;
1578 p->pi_blocked_on = NULL;
1582 #ifdef CONFIG_POSIX_TIMERS
1584 * Initialize POSIX timer handling for a single task.
1586 static void posix_cpu_timers_init(struct task_struct *tsk)
1588 tsk->cputime_expires.prof_exp = 0;
1589 tsk->cputime_expires.virt_exp = 0;
1590 tsk->cputime_expires.sched_exp = 0;
1591 INIT_LIST_HEAD(&tsk->cpu_timers[0]);
1592 INIT_LIST_HEAD(&tsk->cpu_timers[1]);
1593 INIT_LIST_HEAD(&tsk->cpu_timers[2]);
1596 static inline void posix_cpu_timers_init(struct task_struct *tsk) { }
1599 static inline void init_task_pid_links(struct task_struct *task)
1603 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
1604 INIT_HLIST_NODE(&task->pid_links[type]);
1609 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1611 if (type == PIDTYPE_PID)
1612 task->thread_pid = pid;
1614 task->signal->pids[type] = pid;
1617 static inline void rcu_copy_process(struct task_struct *p)
1619 #ifdef CONFIG_PREEMPT_RCU
1620 p->rcu_read_lock_nesting = 0;
1621 p->rcu_read_unlock_special.s = 0;
1622 p->rcu_blocked_node = NULL;
1623 INIT_LIST_HEAD(&p->rcu_node_entry);
1624 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1625 #ifdef CONFIG_TASKS_RCU
1626 p->rcu_tasks_holdout = false;
1627 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1628 p->rcu_tasks_idle_cpu = -1;
1629 #endif /* #ifdef CONFIG_TASKS_RCU */
1632 static void __delayed_free_task(struct rcu_head *rhp)
1634 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1639 static __always_inline void delayed_free_task(struct task_struct *tsk)
1641 if (IS_ENABLED(CONFIG_MEMCG))
1642 call_rcu(&tsk->rcu, __delayed_free_task);
1647 static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1649 /* Skip if kernel thread */
1653 /* Skip if spawning a thread or using vfork */
1654 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1657 /* We need to synchronize with __set_oom_adj */
1658 mutex_lock(&oom_adj_mutex);
1659 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1660 /* Update the values in case they were changed after copy_signal */
1661 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1662 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1663 mutex_unlock(&oom_adj_mutex);
1667 * This creates a new process as a copy of the old one,
1668 * but does not actually start it yet.
1670 * It copies the registers, and all the appropriate
1671 * parts of the process environment (as per the clone
1672 * flags). The actual kick-off is left to the caller.
1674 static __latent_entropy struct task_struct *copy_process(
1675 unsigned long clone_flags,
1676 unsigned long stack_start,
1677 unsigned long stack_size,
1678 int __user *child_tidptr,
1685 struct task_struct *p;
1686 struct multiprocess_signals delayed;
1689 * Don't allow sharing the root directory with processes in a different
1692 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1693 return ERR_PTR(-EINVAL);
1695 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1696 return ERR_PTR(-EINVAL);
1699 * Thread groups must share signals as well, and detached threads
1700 * can only be started up within the thread group.
1702 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1703 return ERR_PTR(-EINVAL);
1706 * Shared signal handlers imply shared VM. By way of the above,
1707 * thread groups also imply shared VM. Blocking this case allows
1708 * for various simplifications in other code.
1710 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1711 return ERR_PTR(-EINVAL);
1714 * Siblings of global init remain as zombies on exit since they are
1715 * not reaped by their parent (swapper). To solve this and to avoid
1716 * multi-rooted process trees, prevent global and container-inits
1717 * from creating siblings.
1719 if ((clone_flags & CLONE_PARENT) &&
1720 current->signal->flags & SIGNAL_UNKILLABLE)
1721 return ERR_PTR(-EINVAL);
1724 * If the new process will be in a different pid or user namespace
1725 * do not allow it to share a thread group with the forking task.
1727 if (clone_flags & CLONE_THREAD) {
1728 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
1729 (task_active_pid_ns(current) !=
1730 current->nsproxy->pid_ns_for_children))
1731 return ERR_PTR(-EINVAL);
1735 * Force any signals received before this point to be delivered
1736 * before the fork happens. Collect up signals sent to multiple
1737 * processes that happen during the fork and delay them so that
1738 * they appear to happen after the fork.
1740 sigemptyset(&delayed.signal);
1741 INIT_HLIST_NODE(&delayed.node);
1743 spin_lock_irq(¤t->sighand->siglock);
1744 if (!(clone_flags & CLONE_THREAD))
1745 hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
1746 recalc_sigpending();
1747 spin_unlock_irq(¤t->sighand->siglock);
1748 retval = -ERESTARTNOINTR;
1749 if (signal_pending(current))
1753 p = dup_task_struct(current, node);
1758 * This _must_ happen before we call free_task(), i.e. before we jump
1759 * to any of the bad_fork_* labels. This is to avoid freeing
1760 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1761 * kernel threads (PF_KTHREAD).
1763 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? child_tidptr : NULL;
1765 * Clear TID on mm_release()?
1767 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? child_tidptr : NULL;
1769 ftrace_graph_init_task(p);
1771 rt_mutex_init_task(p);
1773 #ifdef CONFIG_PROVE_LOCKING
1774 DEBUG_LOCKS_WARN_ON(!p->hardirqs_enabled);
1775 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
1778 if (atomic_read(&p->real_cred->user->processes) >=
1779 task_rlimit(p, RLIMIT_NPROC)) {
1780 if (p->real_cred->user != INIT_USER &&
1781 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
1784 current->flags &= ~PF_NPROC_EXCEEDED;
1786 retval = copy_creds(p, clone_flags);
1791 * If multiple threads are within copy_process(), then this check
1792 * triggers too late. This doesn't hurt, the check is only there
1793 * to stop root fork bombs.
1796 if (nr_threads >= max_threads)
1797 goto bad_fork_cleanup_count;
1799 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
1800 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE);
1801 p->flags |= PF_FORKNOEXEC;
1802 INIT_LIST_HEAD(&p->children);
1803 INIT_LIST_HEAD(&p->sibling);
1804 rcu_copy_process(p);
1805 p->vfork_done = NULL;
1806 spin_lock_init(&p->alloc_lock);
1808 init_sigpending(&p->pending);
1810 p->utime = p->stime = p->gtime = 0;
1811 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1812 p->utimescaled = p->stimescaled = 0;
1814 prev_cputime_init(&p->prev_cputime);
1816 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1817 seqcount_init(&p->vtime.seqcount);
1818 p->vtime.starttime = 0;
1819 p->vtime.state = VTIME_INACTIVE;
1822 #if defined(SPLIT_RSS_COUNTING)
1823 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
1826 p->default_timer_slack_ns = current->timer_slack_ns;
1828 task_io_accounting_init(&p->ioac);
1829 acct_clear_integrals(p);
1831 posix_cpu_timers_init(p);
1833 p->io_context = NULL;
1834 audit_set_context(p, NULL);
1837 p->mempolicy = mpol_dup(p->mempolicy);
1838 if (IS_ERR(p->mempolicy)) {
1839 retval = PTR_ERR(p->mempolicy);
1840 p->mempolicy = NULL;
1841 goto bad_fork_cleanup_threadgroup_lock;
1844 #ifdef CONFIG_CPUSETS
1845 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
1846 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
1847 seqcount_init(&p->mems_allowed_seq);
1849 #ifdef CONFIG_TRACE_IRQFLAGS
1851 p->hardirqs_enabled = 0;
1852 p->hardirq_enable_ip = 0;
1853 p->hardirq_enable_event = 0;
1854 p->hardirq_disable_ip = _THIS_IP_;
1855 p->hardirq_disable_event = 0;
1856 p->softirqs_enabled = 1;
1857 p->softirq_enable_ip = _THIS_IP_;
1858 p->softirq_enable_event = 0;
1859 p->softirq_disable_ip = 0;
1860 p->softirq_disable_event = 0;
1861 p->hardirq_context = 0;
1862 p->softirq_context = 0;
1865 p->pagefault_disabled = 0;
1867 #ifdef CONFIG_LOCKDEP
1868 p->lockdep_depth = 0; /* no locks held yet */
1869 p->curr_chain_key = 0;
1870 p->lockdep_recursion = 0;
1871 lockdep_init_task(p);
1874 #ifdef CONFIG_DEBUG_MUTEXES
1875 p->blocked_on = NULL; /* not blocked yet */
1877 #ifdef CONFIG_BCACHE
1878 p->sequential_io = 0;
1879 p->sequential_io_avg = 0;
1882 /* Perform scheduler related setup. Assign this task to a CPU. */
1883 retval = sched_fork(clone_flags, p);
1885 goto bad_fork_cleanup_policy;
1887 retval = perf_event_init_task(p);
1889 goto bad_fork_cleanup_policy;
1890 retval = audit_alloc(p);
1892 goto bad_fork_cleanup_perf;
1893 /* copy all the process information */
1895 retval = security_task_alloc(p, clone_flags);
1897 goto bad_fork_cleanup_audit;
1898 retval = copy_semundo(clone_flags, p);
1900 goto bad_fork_cleanup_security;
1901 retval = copy_files(clone_flags, p);
1903 goto bad_fork_cleanup_semundo;
1904 retval = copy_fs(clone_flags, p);
1906 goto bad_fork_cleanup_files;
1907 retval = copy_sighand(clone_flags, p);
1909 goto bad_fork_cleanup_fs;
1910 retval = copy_signal(clone_flags, p);
1912 goto bad_fork_cleanup_sighand;
1913 retval = copy_mm(clone_flags, p);
1915 goto bad_fork_cleanup_signal;
1916 retval = copy_namespaces(clone_flags, p);
1918 goto bad_fork_cleanup_mm;
1919 retval = copy_io(clone_flags, p);
1921 goto bad_fork_cleanup_namespaces;
1922 retval = copy_thread_tls(clone_flags, stack_start, stack_size, p, tls);
1924 goto bad_fork_cleanup_io;
1926 if (pid != &init_struct_pid) {
1927 pid = alloc_pid(p->nsproxy->pid_ns_for_children);
1929 retval = PTR_ERR(pid);
1930 goto bad_fork_cleanup_thread;
1940 * sigaltstack should be cleared when sharing the same VM
1942 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
1946 * Syscall tracing and stepping should be turned off in the
1947 * child regardless of CLONE_PTRACE.
1949 user_disable_single_step(p);
1950 clear_tsk_thread_flag(p, TIF_SYSCALL_TRACE);
1951 #ifdef TIF_SYSCALL_EMU
1952 clear_tsk_thread_flag(p, TIF_SYSCALL_EMU);
1954 clear_all_latency_tracing(p);
1956 /* ok, now we should be set up.. */
1957 p->pid = pid_nr(pid);
1958 if (clone_flags & CLONE_THREAD) {
1959 p->group_leader = current->group_leader;
1960 p->tgid = current->tgid;
1962 p->group_leader = p;
1967 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
1968 p->dirty_paused_when = 0;
1970 p->pdeath_signal = 0;
1971 INIT_LIST_HEAD(&p->thread_group);
1972 p->task_works = NULL;
1974 cgroup_threadgroup_change_begin(current);
1976 * Ensure that the cgroup subsystem policies allow the new process to be
1977 * forked. It should be noted the the new process's css_set can be changed
1978 * between here and cgroup_post_fork() if an organisation operation is in
1981 retval = cgroup_can_fork(p);
1983 goto bad_fork_free_pid;
1986 * From this point on we must avoid any synchronous user-space
1987 * communication until we take the tasklist-lock. In particular, we do
1988 * not want user-space to be able to predict the process start-time by
1989 * stalling fork(2) after we recorded the start_time but before it is
1990 * visible to the system.
1993 p->start_time = ktime_get_ns();
1994 p->real_start_time = ktime_get_boot_ns();
1997 * Make it visible to the rest of the system, but dont wake it up yet.
1998 * Need tasklist lock for parent etc handling!
2000 write_lock_irq(&tasklist_lock);
2002 /* CLONE_PARENT re-uses the old parent */
2003 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2004 p->real_parent = current->real_parent;
2005 p->parent_exec_id = current->parent_exec_id;
2006 if (clone_flags & CLONE_THREAD)
2007 p->exit_signal = -1;
2009 p->exit_signal = current->group_leader->exit_signal;
2011 p->real_parent = current;
2012 p->parent_exec_id = current->self_exec_id;
2013 p->exit_signal = (clone_flags & CSIGNAL);
2016 klp_copy_process(p);
2018 spin_lock(¤t->sighand->siglock);
2021 * Copy seccomp details explicitly here, in case they were changed
2022 * before holding sighand lock.
2026 rseq_fork(p, clone_flags);
2028 /* Don't start children in a dying pid namespace */
2029 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2031 goto bad_fork_cancel_cgroup;
2034 /* Let kill terminate clone/fork in the middle */
2035 if (fatal_signal_pending(current)) {
2037 goto bad_fork_cancel_cgroup;
2041 init_task_pid_links(p);
2042 if (likely(p->pid)) {
2043 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2045 init_task_pid(p, PIDTYPE_PID, pid);
2046 if (thread_group_leader(p)) {
2047 init_task_pid(p, PIDTYPE_TGID, pid);
2048 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2049 init_task_pid(p, PIDTYPE_SID, task_session(current));
2051 if (is_child_reaper(pid)) {
2052 ns_of_pid(pid)->child_reaper = p;
2053 p->signal->flags |= SIGNAL_UNKILLABLE;
2055 p->signal->shared_pending.signal = delayed.signal;
2056 p->signal->tty = tty_kref_get(current->signal->tty);
2058 * Inherit has_child_subreaper flag under the same
2059 * tasklist_lock with adding child to the process tree
2060 * for propagate_has_child_subreaper optimization.
2062 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2063 p->real_parent->signal->is_child_subreaper;
2064 list_add_tail(&p->sibling, &p->real_parent->children);
2065 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2066 attach_pid(p, PIDTYPE_TGID);
2067 attach_pid(p, PIDTYPE_PGID);
2068 attach_pid(p, PIDTYPE_SID);
2069 __this_cpu_inc(process_counts);
2071 current->signal->nr_threads++;
2072 atomic_inc(¤t->signal->live);
2073 atomic_inc(¤t->signal->sigcnt);
2074 task_join_group_stop(p);
2075 list_add_tail_rcu(&p->thread_group,
2076 &p->group_leader->thread_group);
2077 list_add_tail_rcu(&p->thread_node,
2078 &p->signal->thread_head);
2080 attach_pid(p, PIDTYPE_PID);
2084 hlist_del_init(&delayed.node);
2085 spin_unlock(¤t->sighand->siglock);
2086 syscall_tracepoint_update(p);
2087 write_unlock_irq(&tasklist_lock);
2089 proc_fork_connector(p);
2090 cgroup_post_fork(p);
2091 cgroup_threadgroup_change_end(current);
2094 trace_task_newtask(p, clone_flags);
2095 uprobe_copy_process(p, clone_flags);
2097 copy_oom_score_adj(clone_flags, p);
2101 bad_fork_cancel_cgroup:
2102 spin_unlock(¤t->sighand->siglock);
2103 write_unlock_irq(&tasklist_lock);
2104 cgroup_cancel_fork(p);
2106 cgroup_threadgroup_change_end(current);
2107 if (pid != &init_struct_pid)
2109 bad_fork_cleanup_thread:
2111 bad_fork_cleanup_io:
2114 bad_fork_cleanup_namespaces:
2115 exit_task_namespaces(p);
2116 bad_fork_cleanup_mm:
2118 mm_clear_owner(p->mm, p);
2121 bad_fork_cleanup_signal:
2122 if (!(clone_flags & CLONE_THREAD))
2123 free_signal_struct(p->signal);
2124 bad_fork_cleanup_sighand:
2125 __cleanup_sighand(p->sighand);
2126 bad_fork_cleanup_fs:
2127 exit_fs(p); /* blocking */
2128 bad_fork_cleanup_files:
2129 exit_files(p); /* blocking */
2130 bad_fork_cleanup_semundo:
2132 bad_fork_cleanup_security:
2133 security_task_free(p);
2134 bad_fork_cleanup_audit:
2136 bad_fork_cleanup_perf:
2137 perf_event_free_task(p);
2138 bad_fork_cleanup_policy:
2139 lockdep_free_task(p);
2141 mpol_put(p->mempolicy);
2142 bad_fork_cleanup_threadgroup_lock:
2144 delayacct_tsk_free(p);
2145 bad_fork_cleanup_count:
2146 atomic_dec(&p->cred->user->processes);
2149 p->state = TASK_DEAD;
2151 delayed_free_task(p);
2153 spin_lock_irq(¤t->sighand->siglock);
2154 hlist_del_init(&delayed.node);
2155 spin_unlock_irq(¤t->sighand->siglock);
2156 return ERR_PTR(retval);
2159 static inline void init_idle_pids(struct task_struct *idle)
2163 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2164 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2165 init_task_pid(idle, type, &init_struct_pid);
2169 struct task_struct *fork_idle(int cpu)
2171 struct task_struct *task;
2172 task = copy_process(CLONE_VM, 0, 0, NULL, &init_struct_pid, 0, 0,
2174 if (!IS_ERR(task)) {
2175 init_idle_pids(task);
2176 init_idle(task, cpu);
2183 * Ok, this is the main fork-routine.
2185 * It copies the process, and if successful kick-starts
2186 * it and waits for it to finish using the VM if required.
2188 long _do_fork(unsigned long clone_flags,
2189 unsigned long stack_start,
2190 unsigned long stack_size,
2191 int __user *parent_tidptr,
2192 int __user *child_tidptr,
2195 struct completion vfork;
2197 struct task_struct *p;
2202 * Determine whether and which event to report to ptracer. When
2203 * called from kernel_thread or CLONE_UNTRACED is explicitly
2204 * requested, no event is reported; otherwise, report if the event
2205 * for the type of forking is enabled.
2207 if (!(clone_flags & CLONE_UNTRACED)) {
2208 if (clone_flags & CLONE_VFORK)
2209 trace = PTRACE_EVENT_VFORK;
2210 else if ((clone_flags & CSIGNAL) != SIGCHLD)
2211 trace = PTRACE_EVENT_CLONE;
2213 trace = PTRACE_EVENT_FORK;
2215 if (likely(!ptrace_event_enabled(current, trace)))
2219 p = copy_process(clone_flags, stack_start, stack_size,
2220 child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
2221 add_latent_entropy();
2227 * Do this prior waking up the new thread - the thread pointer
2228 * might get invalid after that point, if the thread exits quickly.
2230 trace_sched_process_fork(current, p);
2232 pid = get_task_pid(p, PIDTYPE_PID);
2235 if (clone_flags & CLONE_PARENT_SETTID)
2236 put_user(nr, parent_tidptr);
2238 if (clone_flags & CLONE_VFORK) {
2239 p->vfork_done = &vfork;
2240 init_completion(&vfork);
2244 wake_up_new_task(p);
2246 /* forking complete and child started to run, tell ptracer */
2247 if (unlikely(trace))
2248 ptrace_event_pid(trace, pid);
2250 if (clone_flags & CLONE_VFORK) {
2251 if (!wait_for_vfork_done(p, &vfork))
2252 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2259 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2260 /* For compatibility with architectures that call do_fork directly rather than
2261 * using the syscall entry points below. */
2262 long do_fork(unsigned long clone_flags,
2263 unsigned long stack_start,
2264 unsigned long stack_size,
2265 int __user *parent_tidptr,
2266 int __user *child_tidptr)
2268 return _do_fork(clone_flags, stack_start, stack_size,
2269 parent_tidptr, child_tidptr, 0);
2274 * Create a kernel thread.
2276 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2278 return _do_fork(flags|CLONE_VM|CLONE_UNTRACED, (unsigned long)fn,
2279 (unsigned long)arg, NULL, NULL, 0);
2282 #ifdef __ARCH_WANT_SYS_FORK
2283 SYSCALL_DEFINE0(fork)
2286 return _do_fork(SIGCHLD, 0, 0, NULL, NULL, 0);
2288 /* can not support in nommu mode */
2294 #ifdef __ARCH_WANT_SYS_VFORK
2295 SYSCALL_DEFINE0(vfork)
2297 return _do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, 0,
2302 #ifdef __ARCH_WANT_SYS_CLONE
2303 #ifdef CONFIG_CLONE_BACKWARDS
2304 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2305 int __user *, parent_tidptr,
2307 int __user *, child_tidptr)
2308 #elif defined(CONFIG_CLONE_BACKWARDS2)
2309 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2310 int __user *, parent_tidptr,
2311 int __user *, child_tidptr,
2313 #elif defined(CONFIG_CLONE_BACKWARDS3)
2314 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2316 int __user *, parent_tidptr,
2317 int __user *, child_tidptr,
2320 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2321 int __user *, parent_tidptr,
2322 int __user *, child_tidptr,
2326 return _do_fork(clone_flags, newsp, 0, parent_tidptr, child_tidptr, tls);
2330 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2332 struct task_struct *leader, *parent, *child;
2335 read_lock(&tasklist_lock);
2336 leader = top = top->group_leader;
2338 for_each_thread(leader, parent) {
2339 list_for_each_entry(child, &parent->children, sibling) {
2340 res = visitor(child, data);
2352 if (leader != top) {
2354 parent = child->real_parent;
2355 leader = parent->group_leader;
2359 read_unlock(&tasklist_lock);
2362 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2363 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2366 static void sighand_ctor(void *data)
2368 struct sighand_struct *sighand = data;
2370 spin_lock_init(&sighand->siglock);
2371 init_waitqueue_head(&sighand->signalfd_wqh);
2374 void __init proc_caches_init(void)
2376 unsigned int mm_size;
2378 sighand_cachep = kmem_cache_create("sighand_cache",
2379 sizeof(struct sighand_struct), 0,
2380 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2381 SLAB_ACCOUNT, sighand_ctor);
2382 signal_cachep = kmem_cache_create("signal_cache",
2383 sizeof(struct signal_struct), 0,
2384 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2386 files_cachep = kmem_cache_create("files_cache",
2387 sizeof(struct files_struct), 0,
2388 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2390 fs_cachep = kmem_cache_create("fs_cache",
2391 sizeof(struct fs_struct), 0,
2392 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2396 * The mm_cpumask is located at the end of mm_struct, and is
2397 * dynamically sized based on the maximum CPU number this system
2398 * can have, taking hotplug into account (nr_cpu_ids).
2400 mm_size = sizeof(struct mm_struct) + cpumask_size();
2402 mm_cachep = kmem_cache_create_usercopy("mm_struct",
2403 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
2404 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2405 offsetof(struct mm_struct, saved_auxv),
2406 sizeof_field(struct mm_struct, saved_auxv),
2408 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
2410 nsproxy_cache_init();
2414 * Check constraints on flags passed to the unshare system call.
2416 static int check_unshare_flags(unsigned long unshare_flags)
2418 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
2419 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
2420 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
2421 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP))
2424 * Not implemented, but pretend it works if there is nothing
2425 * to unshare. Note that unsharing the address space or the
2426 * signal handlers also need to unshare the signal queues (aka
2429 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
2430 if (!thread_group_empty(current))
2433 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
2434 if (atomic_read(¤t->sighand->count) > 1)
2437 if (unshare_flags & CLONE_VM) {
2438 if (!current_is_single_threaded())
2446 * Unshare the filesystem structure if it is being shared
2448 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
2450 struct fs_struct *fs = current->fs;
2452 if (!(unshare_flags & CLONE_FS) || !fs)
2455 /* don't need lock here; in the worst case we'll do useless copy */
2459 *new_fsp = copy_fs_struct(fs);
2467 * Unshare file descriptor table if it is being shared
2469 static int unshare_fd(unsigned long unshare_flags, struct files_struct **new_fdp)
2471 struct files_struct *fd = current->files;
2474 if ((unshare_flags & CLONE_FILES) &&
2475 (fd && atomic_read(&fd->count) > 1)) {
2476 *new_fdp = dup_fd(fd, &error);
2485 * unshare allows a process to 'unshare' part of the process
2486 * context which was originally shared using clone. copy_*
2487 * functions used by do_fork() cannot be used here directly
2488 * because they modify an inactive task_struct that is being
2489 * constructed. Here we are modifying the current, active,
2492 int ksys_unshare(unsigned long unshare_flags)
2494 struct fs_struct *fs, *new_fs = NULL;
2495 struct files_struct *fd, *new_fd = NULL;
2496 struct cred *new_cred = NULL;
2497 struct nsproxy *new_nsproxy = NULL;
2502 * If unsharing a user namespace must also unshare the thread group
2503 * and unshare the filesystem root and working directories.
2505 if (unshare_flags & CLONE_NEWUSER)
2506 unshare_flags |= CLONE_THREAD | CLONE_FS;
2508 * If unsharing vm, must also unshare signal handlers.
2510 if (unshare_flags & CLONE_VM)
2511 unshare_flags |= CLONE_SIGHAND;
2513 * If unsharing a signal handlers, must also unshare the signal queues.
2515 if (unshare_flags & CLONE_SIGHAND)
2516 unshare_flags |= CLONE_THREAD;
2518 * If unsharing namespace, must also unshare filesystem information.
2520 if (unshare_flags & CLONE_NEWNS)
2521 unshare_flags |= CLONE_FS;
2523 err = check_unshare_flags(unshare_flags);
2525 goto bad_unshare_out;
2527 * CLONE_NEWIPC must also detach from the undolist: after switching
2528 * to a new ipc namespace, the semaphore arrays from the old
2529 * namespace are unreachable.
2531 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
2533 err = unshare_fs(unshare_flags, &new_fs);
2535 goto bad_unshare_out;
2536 err = unshare_fd(unshare_flags, &new_fd);
2538 goto bad_unshare_cleanup_fs;
2539 err = unshare_userns(unshare_flags, &new_cred);
2541 goto bad_unshare_cleanup_fd;
2542 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
2545 goto bad_unshare_cleanup_cred;
2547 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
2550 * CLONE_SYSVSEM is equivalent to sys_exit().
2554 if (unshare_flags & CLONE_NEWIPC) {
2555 /* Orphan segments in old ns (see sem above). */
2557 shm_init_task(current);
2561 switch_task_namespaces(current, new_nsproxy);
2567 spin_lock(&fs->lock);
2568 current->fs = new_fs;
2573 spin_unlock(&fs->lock);
2577 fd = current->files;
2578 current->files = new_fd;
2582 task_unlock(current);
2585 /* Install the new user namespace */
2586 commit_creds(new_cred);
2591 perf_event_namespaces(current);
2593 bad_unshare_cleanup_cred:
2596 bad_unshare_cleanup_fd:
2598 put_files_struct(new_fd);
2600 bad_unshare_cleanup_fs:
2602 free_fs_struct(new_fs);
2608 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
2610 return ksys_unshare(unshare_flags);
2614 * Helper to unshare the files of the current task.
2615 * We don't want to expose copy_files internals to
2616 * the exec layer of the kernel.
2619 int unshare_files(struct files_struct **displaced)
2621 struct task_struct *task = current;
2622 struct files_struct *copy = NULL;
2625 error = unshare_fd(CLONE_FILES, ©);
2626 if (error || !copy) {
2630 *displaced = task->files;
2637 int sysctl_max_threads(struct ctl_table *table, int write,
2638 void __user *buffer, size_t *lenp, loff_t *ppos)
2642 int threads = max_threads;
2644 int max = MAX_THREADS;
2651 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
2655 max_threads = threads;