1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * 'fork.c' contains the help-routines for the 'fork' system call
10 * (see also entry.S and others).
11 * Fork is rather simple, once you get the hang of it, but the memory
12 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
15 #include <linux/anon_inodes.h>
16 #include <linux/slab.h>
17 #include <linux/sched/autogroup.h>
18 #include <linux/sched/mm.h>
19 #include <linux/sched/coredump.h>
20 #include <linux/sched/user.h>
21 #include <linux/sched/numa_balancing.h>
22 #include <linux/sched/stat.h>
23 #include <linux/sched/task.h>
24 #include <linux/sched/task_stack.h>
25 #include <linux/sched/cputime.h>
26 #include <linux/seq_file.h>
27 #include <linux/rtmutex.h>
28 #include <linux/init.h>
29 #include <linux/unistd.h>
30 #include <linux/module.h>
31 #include <linux/vmalloc.h>
32 #include <linux/completion.h>
33 #include <linux/personality.h>
34 #include <linux/mempolicy.h>
35 #include <linux/sem.h>
36 #include <linux/file.h>
37 #include <linux/fdtable.h>
38 #include <linux/iocontext.h>
39 #include <linux/key.h>
40 #include <linux/binfmts.h>
41 #include <linux/mman.h>
42 #include <linux/mmu_notifier.h>
45 #include <linux/mm_inline.h>
46 #include <linux/vmacache.h>
47 #include <linux/nsproxy.h>
48 #include <linux/capability.h>
49 #include <linux/cpu.h>
50 #include <linux/cgroup.h>
51 #include <linux/security.h>
52 #include <linux/hugetlb.h>
53 #include <linux/seccomp.h>
54 #include <linux/swap.h>
55 #include <linux/syscalls.h>
56 #include <linux/jiffies.h>
57 #include <linux/futex.h>
58 #include <linux/compat.h>
59 #include <linux/kthread.h>
60 #include <linux/task_io_accounting_ops.h>
61 #include <linux/rcupdate.h>
62 #include <linux/ptrace.h>
63 #include <linux/mount.h>
64 #include <linux/audit.h>
65 #include <linux/memcontrol.h>
66 #include <linux/ftrace.h>
67 #include <linux/proc_fs.h>
68 #include <linux/profile.h>
69 #include <linux/rmap.h>
70 #include <linux/ksm.h>
71 #include <linux/acct.h>
72 #include <linux/userfaultfd_k.h>
73 #include <linux/tsacct_kern.h>
74 #include <linux/cn_proc.h>
75 #include <linux/freezer.h>
76 #include <linux/delayacct.h>
77 #include <linux/taskstats_kern.h>
78 #include <linux/random.h>
79 #include <linux/tty.h>
80 #include <linux/fs_struct.h>
81 #include <linux/magic.h>
82 #include <linux/perf_event.h>
83 #include <linux/posix-timers.h>
84 #include <linux/user-return-notifier.h>
85 #include <linux/oom.h>
86 #include <linux/khugepaged.h>
87 #include <linux/signalfd.h>
88 #include <linux/uprobes.h>
89 #include <linux/aio.h>
90 #include <linux/compiler.h>
91 #include <linux/sysctl.h>
92 #include <linux/kcov.h>
93 #include <linux/livepatch.h>
94 #include <linux/thread_info.h>
95 #include <linux/stackleak.h>
96 #include <linux/kasan.h>
97 #include <linux/scs.h>
98 #include <linux/io_uring.h>
99 #include <linux/bpf.h>
100 #include <linux/sched/mm.h>
102 #include <asm/pgalloc.h>
103 #include <linux/uaccess.h>
104 #include <asm/mmu_context.h>
105 #include <asm/cacheflush.h>
106 #include <asm/tlbflush.h>
108 #include <trace/events/sched.h>
110 #define CREATE_TRACE_POINTS
111 #include <trace/events/task.h>
114 * Minimum number of threads to boot the kernel
116 #define MIN_THREADS 20
119 * Maximum number of threads
121 #define MAX_THREADS FUTEX_TID_MASK
124 * Protected counters by write_lock_irq(&tasklist_lock)
126 unsigned long total_forks; /* Handle normal Linux uptimes. */
127 int nr_threads; /* The idle threads do not count.. */
129 static int max_threads; /* tunable limit on nr_threads */
131 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
133 static const char * const resident_page_types[] = {
134 NAMED_ARRAY_INDEX(MM_FILEPAGES),
135 NAMED_ARRAY_INDEX(MM_ANONPAGES),
136 NAMED_ARRAY_INDEX(MM_SWAPENTS),
137 NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
140 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
142 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
144 #ifdef CONFIG_PROVE_RCU
145 int lockdep_tasklist_lock_is_held(void)
147 return lockdep_is_held(&tasklist_lock);
149 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
150 #endif /* #ifdef CONFIG_PROVE_RCU */
152 int nr_processes(void)
157 for_each_possible_cpu(cpu)
158 total += per_cpu(process_counts, cpu);
163 void __weak arch_release_task_struct(struct task_struct *tsk)
167 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
168 static struct kmem_cache *task_struct_cachep;
170 static inline struct task_struct *alloc_task_struct_node(int node)
172 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
175 static inline void free_task_struct(struct task_struct *tsk)
177 kmem_cache_free(task_struct_cachep, tsk);
181 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
184 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
185 * kmemcache based allocator.
187 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
189 # ifdef CONFIG_VMAP_STACK
191 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
192 * flush. Try to minimize the number of calls by caching stacks.
194 #define NR_CACHED_STACKS 2
195 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
199 struct vm_struct *stack_vm_area;
202 static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
206 for (i = 0; i < NR_CACHED_STACKS; i++) {
207 if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
214 static void thread_stack_free_rcu(struct rcu_head *rh)
216 struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
218 if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
224 static void thread_stack_delayed_free(struct task_struct *tsk)
226 struct vm_stack *vm_stack = tsk->stack;
228 vm_stack->stack_vm_area = tsk->stack_vm_area;
229 call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
232 static int free_vm_stack_cache(unsigned int cpu)
234 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
237 for (i = 0; i < NR_CACHED_STACKS; i++) {
238 struct vm_struct *vm_stack = cached_vm_stacks[i];
243 vfree(vm_stack->addr);
244 cached_vm_stacks[i] = NULL;
250 static int memcg_charge_kernel_stack(struct vm_struct *vm)
255 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
256 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
258 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
259 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
266 * If memcg_kmem_charge_page() fails, page's memory cgroup pointer is
267 * NULL, and memcg_kmem_uncharge_page() in free_thread_stack() will
270 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
271 memcg_kmem_uncharge_page(vm->pages[i], 0);
275 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
277 struct vm_struct *vm;
281 for (i = 0; i < NR_CACHED_STACKS; i++) {
284 s = this_cpu_xchg(cached_stacks[i], NULL);
289 /* Reset stack metadata. */
290 kasan_unpoison_range(s->addr, THREAD_SIZE);
292 stack = kasan_reset_tag(s->addr);
294 /* Clear stale pointers from reused stack. */
295 memset(stack, 0, THREAD_SIZE);
297 if (memcg_charge_kernel_stack(s)) {
302 tsk->stack_vm_area = s;
308 * Allocated stacks are cached and later reused by new threads,
309 * so memcg accounting is performed manually on assigning/releasing
310 * stacks to tasks. Drop __GFP_ACCOUNT.
312 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
313 VMALLOC_START, VMALLOC_END,
314 THREADINFO_GFP & ~__GFP_ACCOUNT,
316 0, node, __builtin_return_address(0));
320 vm = find_vm_area(stack);
321 if (memcg_charge_kernel_stack(vm)) {
326 * We can't call find_vm_area() in interrupt context, and
327 * free_thread_stack() can be called in interrupt context,
328 * so cache the vm_struct.
330 tsk->stack_vm_area = vm;
331 stack = kasan_reset_tag(stack);
336 static void free_thread_stack(struct task_struct *tsk)
338 if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
339 thread_stack_delayed_free(tsk);
342 tsk->stack_vm_area = NULL;
345 # else /* !CONFIG_VMAP_STACK */
347 static void thread_stack_free_rcu(struct rcu_head *rh)
349 __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
352 static void thread_stack_delayed_free(struct task_struct *tsk)
354 struct rcu_head *rh = tsk->stack;
356 call_rcu(rh, thread_stack_free_rcu);
359 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
361 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
365 tsk->stack = kasan_reset_tag(page_address(page));
371 static void free_thread_stack(struct task_struct *tsk)
373 thread_stack_delayed_free(tsk);
377 # endif /* CONFIG_VMAP_STACK */
378 # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
380 static struct kmem_cache *thread_stack_cache;
382 static void thread_stack_free_rcu(struct rcu_head *rh)
384 kmem_cache_free(thread_stack_cache, rh);
387 static void thread_stack_delayed_free(struct task_struct *tsk)
389 struct rcu_head *rh = tsk->stack;
391 call_rcu(rh, thread_stack_free_rcu);
394 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
396 unsigned long *stack;
397 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
398 stack = kasan_reset_tag(stack);
400 return stack ? 0 : -ENOMEM;
403 static void free_thread_stack(struct task_struct *tsk)
405 thread_stack_delayed_free(tsk);
409 void thread_stack_cache_init(void)
411 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
412 THREAD_SIZE, THREAD_SIZE, 0, 0,
414 BUG_ON(thread_stack_cache == NULL);
417 # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
418 #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
420 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
422 unsigned long *stack;
424 stack = arch_alloc_thread_stack_node(tsk, node);
426 return stack ? 0 : -ENOMEM;
429 static void free_thread_stack(struct task_struct *tsk)
431 arch_free_thread_stack(tsk);
435 #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
437 /* SLAB cache for signal_struct structures (tsk->signal) */
438 static struct kmem_cache *signal_cachep;
440 /* SLAB cache for sighand_struct structures (tsk->sighand) */
441 struct kmem_cache *sighand_cachep;
443 /* SLAB cache for files_struct structures (tsk->files) */
444 struct kmem_cache *files_cachep;
446 /* SLAB cache for fs_struct structures (tsk->fs) */
447 struct kmem_cache *fs_cachep;
449 /* SLAB cache for vm_area_struct structures */
450 static struct kmem_cache *vm_area_cachep;
452 /* SLAB cache for mm_struct structures (tsk->mm) */
453 static struct kmem_cache *mm_cachep;
455 struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
457 struct vm_area_struct *vma;
459 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
465 struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
467 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
470 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
471 ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
473 * orig->shared.rb may be modified concurrently, but the clone
474 * will be reinitialized.
476 *new = data_race(*orig);
477 INIT_LIST_HEAD(&new->anon_vma_chain);
478 new->vm_next = new->vm_prev = NULL;
479 dup_anon_vma_name(orig, new);
484 void vm_area_free(struct vm_area_struct *vma)
486 free_anon_vma_name(vma);
487 kmem_cache_free(vm_area_cachep, vma);
490 static void account_kernel_stack(struct task_struct *tsk, int account)
492 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
493 struct vm_struct *vm = task_stack_vm_area(tsk);
496 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
497 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
498 account * (PAGE_SIZE / 1024));
500 void *stack = task_stack_page(tsk);
502 /* All stack pages are in the same node. */
503 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
504 account * (THREAD_SIZE / 1024));
508 void exit_task_stack_account(struct task_struct *tsk)
510 account_kernel_stack(tsk, -1);
512 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
513 struct vm_struct *vm;
516 vm = task_stack_vm_area(tsk);
517 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
518 memcg_kmem_uncharge_page(vm->pages[i], 0);
522 static void release_task_stack(struct task_struct *tsk)
524 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
525 return; /* Better to leak the stack than to free prematurely */
527 free_thread_stack(tsk);
530 #ifdef CONFIG_THREAD_INFO_IN_TASK
531 void put_task_stack(struct task_struct *tsk)
533 if (refcount_dec_and_test(&tsk->stack_refcount))
534 release_task_stack(tsk);
538 void free_task(struct task_struct *tsk)
540 release_user_cpus_ptr(tsk);
543 #ifndef CONFIG_THREAD_INFO_IN_TASK
545 * The task is finally done with both the stack and thread_info,
548 release_task_stack(tsk);
551 * If the task had a separate stack allocation, it should be gone
554 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
556 rt_mutex_debug_task_free(tsk);
557 ftrace_graph_exit_task(tsk);
558 arch_release_task_struct(tsk);
559 if (tsk->flags & PF_KTHREAD)
560 free_kthread_struct(tsk);
561 free_task_struct(tsk);
563 EXPORT_SYMBOL(free_task);
565 static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
567 struct file *exe_file;
569 exe_file = get_mm_exe_file(oldmm);
570 RCU_INIT_POINTER(mm->exe_file, exe_file);
572 * We depend on the oldmm having properly denied write access to the
575 if (exe_file && deny_write_access(exe_file))
576 pr_warn_once("deny_write_access() failed in %s\n", __func__);
580 static __latent_entropy int dup_mmap(struct mm_struct *mm,
581 struct mm_struct *oldmm)
583 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
584 struct rb_node **rb_link, *rb_parent;
586 unsigned long charge;
589 uprobe_start_dup_mmap();
590 if (mmap_write_lock_killable(oldmm)) {
592 goto fail_uprobe_end;
594 flush_cache_dup_mm(oldmm);
595 uprobe_dup_mmap(oldmm, mm);
597 * Not linked in yet - no deadlock potential:
599 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
601 /* No ordering required: file already has been exposed. */
602 dup_mm_exe_file(mm, oldmm);
604 mm->total_vm = oldmm->total_vm;
605 mm->data_vm = oldmm->data_vm;
606 mm->exec_vm = oldmm->exec_vm;
607 mm->stack_vm = oldmm->stack_vm;
609 rb_link = &mm->mm_rb.rb_node;
612 retval = ksm_fork(mm, oldmm);
615 khugepaged_fork(mm, oldmm);
618 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
621 if (mpnt->vm_flags & VM_DONTCOPY) {
622 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
627 * Don't duplicate many vmas if we've been oom-killed (for
630 if (fatal_signal_pending(current)) {
634 if (mpnt->vm_flags & VM_ACCOUNT) {
635 unsigned long len = vma_pages(mpnt);
637 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
641 tmp = vm_area_dup(mpnt);
644 retval = vma_dup_policy(mpnt, tmp);
646 goto fail_nomem_policy;
648 retval = dup_userfaultfd(tmp, &uf);
650 goto fail_nomem_anon_vma_fork;
651 if (tmp->vm_flags & VM_WIPEONFORK) {
653 * VM_WIPEONFORK gets a clean slate in the child.
654 * Don't prepare anon_vma until fault since we don't
655 * copy page for current vma.
657 tmp->anon_vma = NULL;
658 } else if (anon_vma_fork(tmp, mpnt))
659 goto fail_nomem_anon_vma_fork;
660 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
663 struct address_space *mapping = file->f_mapping;
666 i_mmap_lock_write(mapping);
667 if (tmp->vm_flags & VM_SHARED)
668 mapping_allow_writable(mapping);
669 flush_dcache_mmap_lock(mapping);
670 /* insert tmp into the share list, just after mpnt */
671 vma_interval_tree_insert_after(tmp, mpnt,
673 flush_dcache_mmap_unlock(mapping);
674 i_mmap_unlock_write(mapping);
678 * Clear hugetlb-related page reserves for children. This only
679 * affects MAP_PRIVATE mappings. Faults generated by the child
680 * are not guaranteed to succeed, even if read-only
682 if (is_vm_hugetlb_page(tmp))
683 reset_vma_resv_huge_pages(tmp);
686 * Link in the new vma and copy the page table entries.
689 pprev = &tmp->vm_next;
693 __vma_link_rb(mm, tmp, rb_link, rb_parent);
694 rb_link = &tmp->vm_rb.rb_right;
695 rb_parent = &tmp->vm_rb;
698 if (!(tmp->vm_flags & VM_WIPEONFORK))
699 retval = copy_page_range(tmp, mpnt);
701 if (tmp->vm_ops && tmp->vm_ops->open)
702 tmp->vm_ops->open(tmp);
707 /* a new mm has just been created */
708 retval = arch_dup_mmap(oldmm, mm);
710 mmap_write_unlock(mm);
712 mmap_write_unlock(oldmm);
713 dup_userfaultfd_complete(&uf);
715 uprobe_end_dup_mmap();
717 fail_nomem_anon_vma_fork:
718 mpol_put(vma_policy(tmp));
723 vm_unacct_memory(charge);
727 static inline int mm_alloc_pgd(struct mm_struct *mm)
729 mm->pgd = pgd_alloc(mm);
730 if (unlikely(!mm->pgd))
735 static inline void mm_free_pgd(struct mm_struct *mm)
737 pgd_free(mm, mm->pgd);
740 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
742 mmap_write_lock(oldmm);
743 dup_mm_exe_file(mm, oldmm);
744 mmap_write_unlock(oldmm);
747 #define mm_alloc_pgd(mm) (0)
748 #define mm_free_pgd(mm)
749 #endif /* CONFIG_MMU */
751 static void check_mm(struct mm_struct *mm)
755 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
756 "Please make sure 'struct resident_page_types[]' is updated as well");
758 for (i = 0; i < NR_MM_COUNTERS; i++) {
759 long x = atomic_long_read(&mm->rss_stat.count[i]);
762 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
763 mm, resident_page_types[i], x);
766 if (mm_pgtables_bytes(mm))
767 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
768 mm_pgtables_bytes(mm));
770 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
771 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
775 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
776 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
779 * Called when the last reference to the mm
780 * is dropped: either by a lazy thread or by
781 * mmput. Free the page directory and the mm.
783 void __mmdrop(struct mm_struct *mm)
785 BUG_ON(mm == &init_mm);
786 WARN_ON_ONCE(mm == current->mm);
787 WARN_ON_ONCE(mm == current->active_mm);
790 mmu_notifier_subscriptions_destroy(mm);
792 put_user_ns(mm->user_ns);
796 EXPORT_SYMBOL_GPL(__mmdrop);
798 static void mmdrop_async_fn(struct work_struct *work)
800 struct mm_struct *mm;
802 mm = container_of(work, struct mm_struct, async_put_work);
806 static void mmdrop_async(struct mm_struct *mm)
808 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
809 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
810 schedule_work(&mm->async_put_work);
814 static inline void free_signal_struct(struct signal_struct *sig)
816 taskstats_tgid_free(sig);
817 sched_autogroup_exit(sig);
819 * __mmdrop is not safe to call from softirq context on x86 due to
820 * pgd_dtor so postpone it to the async context
823 mmdrop_async(sig->oom_mm);
824 kmem_cache_free(signal_cachep, sig);
827 static inline void put_signal_struct(struct signal_struct *sig)
829 if (refcount_dec_and_test(&sig->sigcnt))
830 free_signal_struct(sig);
833 void __put_task_struct(struct task_struct *tsk)
835 WARN_ON(!tsk->exit_state);
836 WARN_ON(refcount_read(&tsk->usage));
837 WARN_ON(tsk == current);
841 task_numa_free(tsk, true);
842 security_task_free(tsk);
843 bpf_task_storage_free(tsk);
845 delayacct_tsk_free(tsk);
846 put_signal_struct(tsk->signal);
847 sched_core_free(tsk);
850 EXPORT_SYMBOL_GPL(__put_task_struct);
852 void __init __weak arch_task_cache_init(void) { }
857 static void set_max_threads(unsigned int max_threads_suggested)
860 unsigned long nr_pages = totalram_pages();
863 * The number of threads shall be limited such that the thread
864 * structures may only consume a small part of the available memory.
866 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
867 threads = MAX_THREADS;
869 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
870 (u64) THREAD_SIZE * 8UL);
872 if (threads > max_threads_suggested)
873 threads = max_threads_suggested;
875 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
878 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
879 /* Initialized by the architecture: */
880 int arch_task_struct_size __read_mostly;
883 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
884 static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
886 /* Fetch thread_struct whitelist for the architecture. */
887 arch_thread_struct_whitelist(offset, size);
890 * Handle zero-sized whitelist or empty thread_struct, otherwise
891 * adjust offset to position of thread_struct in task_struct.
893 if (unlikely(*size == 0))
896 *offset += offsetof(struct task_struct, thread);
898 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
900 void __init fork_init(void)
903 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
904 #ifndef ARCH_MIN_TASKALIGN
905 #define ARCH_MIN_TASKALIGN 0
907 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
908 unsigned long useroffset, usersize;
910 /* create a slab on which task_structs can be allocated */
911 task_struct_whitelist(&useroffset, &usersize);
912 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
913 arch_task_struct_size, align,
914 SLAB_PANIC|SLAB_ACCOUNT,
915 useroffset, usersize, NULL);
918 /* do the arch specific task caches init */
919 arch_task_cache_init();
921 set_max_threads(MAX_THREADS);
923 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
924 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
925 init_task.signal->rlim[RLIMIT_SIGPENDING] =
926 init_task.signal->rlim[RLIMIT_NPROC];
928 for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++)
929 init_user_ns.ucount_max[i] = max_threads/2;
931 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
932 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
933 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
934 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
936 #ifdef CONFIG_VMAP_STACK
937 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
938 NULL, free_vm_stack_cache);
943 lockdep_init_task(&init_task);
947 int __weak arch_dup_task_struct(struct task_struct *dst,
948 struct task_struct *src)
954 void set_task_stack_end_magic(struct task_struct *tsk)
956 unsigned long *stackend;
958 stackend = end_of_stack(tsk);
959 *stackend = STACK_END_MAGIC; /* for overflow detection */
962 static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
964 struct task_struct *tsk;
967 if (node == NUMA_NO_NODE)
968 node = tsk_fork_get_node(orig);
969 tsk = alloc_task_struct_node(node);
973 err = arch_dup_task_struct(tsk, orig);
977 err = alloc_thread_stack_node(tsk, node);
981 #ifdef CONFIG_THREAD_INFO_IN_TASK
982 refcount_set(&tsk->stack_refcount, 1);
984 account_kernel_stack(tsk, 1);
986 err = scs_prepare(tsk, node);
990 #ifdef CONFIG_SECCOMP
992 * We must handle setting up seccomp filters once we're under
993 * the sighand lock in case orig has changed between now and
994 * then. Until then, filter must be NULL to avoid messing up
995 * the usage counts on the error path calling free_task.
997 tsk->seccomp.filter = NULL;
1000 setup_thread_stack(tsk, orig);
1001 clear_user_return_notifier(tsk);
1002 clear_tsk_need_resched(tsk);
1003 set_task_stack_end_magic(tsk);
1004 clear_syscall_work_syscall_user_dispatch(tsk);
1006 #ifdef CONFIG_STACKPROTECTOR
1007 tsk->stack_canary = get_random_canary();
1009 if (orig->cpus_ptr == &orig->cpus_mask)
1010 tsk->cpus_ptr = &tsk->cpus_mask;
1011 dup_user_cpus_ptr(tsk, orig, node);
1014 * One for the user space visible state that goes away when reaped.
1015 * One for the scheduler.
1017 refcount_set(&tsk->rcu_users, 2);
1018 /* One for the rcu users */
1019 refcount_set(&tsk->usage, 1);
1020 #ifdef CONFIG_BLK_DEV_IO_TRACE
1021 tsk->btrace_seq = 0;
1023 tsk->splice_pipe = NULL;
1024 tsk->task_frag.page = NULL;
1025 tsk->wake_q.next = NULL;
1026 tsk->worker_private = NULL;
1028 kcov_task_init(tsk);
1029 kmap_local_fork(tsk);
1031 #ifdef CONFIG_FAULT_INJECTION
1035 #ifdef CONFIG_BLK_CGROUP
1036 tsk->throttle_queue = NULL;
1037 tsk->use_memdelay = 0;
1040 #ifdef CONFIG_IOMMU_SVA
1041 tsk->pasid_activated = 0;
1045 tsk->active_memcg = NULL;
1048 #ifdef CONFIG_CPU_SUP_INTEL
1049 tsk->reported_split_lock = 0;
1055 exit_task_stack_account(tsk);
1056 free_thread_stack(tsk);
1058 free_task_struct(tsk);
1062 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1064 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1066 static int __init coredump_filter_setup(char *s)
1068 default_dump_filter =
1069 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1070 MMF_DUMP_FILTER_MASK;
1074 __setup("coredump_filter=", coredump_filter_setup);
1076 #include <linux/init_task.h>
1078 static void mm_init_aio(struct mm_struct *mm)
1081 spin_lock_init(&mm->ioctx_lock);
1082 mm->ioctx_table = NULL;
1086 static __always_inline void mm_clear_owner(struct mm_struct *mm,
1087 struct task_struct *p)
1091 WRITE_ONCE(mm->owner, NULL);
1095 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1102 static void mm_init_uprobes_state(struct mm_struct *mm)
1104 #ifdef CONFIG_UPROBES
1105 mm->uprobes_state.xol_area = NULL;
1109 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1110 struct user_namespace *user_ns)
1113 mm->mm_rb = RB_ROOT;
1114 mm->vmacache_seqnum = 0;
1115 atomic_set(&mm->mm_users, 1);
1116 atomic_set(&mm->mm_count, 1);
1117 seqcount_init(&mm->write_protect_seq);
1119 INIT_LIST_HEAD(&mm->mmlist);
1120 mm_pgtables_bytes_init(mm);
1123 atomic64_set(&mm->pinned_vm, 0);
1124 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1125 spin_lock_init(&mm->page_table_lock);
1126 spin_lock_init(&mm->arg_lock);
1127 mm_init_cpumask(mm);
1129 mm_init_owner(mm, p);
1131 RCU_INIT_POINTER(mm->exe_file, NULL);
1132 mmu_notifier_subscriptions_init(mm);
1133 init_tlb_flush_pending(mm);
1134 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1135 mm->pmd_huge_pte = NULL;
1137 mm_init_uprobes_state(mm);
1138 hugetlb_count_init(mm);
1141 mm->flags = current->mm->flags & MMF_INIT_MASK;
1142 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1144 mm->flags = default_dump_filter;
1148 if (mm_alloc_pgd(mm))
1151 if (init_new_context(p, mm))
1152 goto fail_nocontext;
1154 mm->user_ns = get_user_ns(user_ns);
1165 * Allocate and initialize an mm_struct.
1167 struct mm_struct *mm_alloc(void)
1169 struct mm_struct *mm;
1175 memset(mm, 0, sizeof(*mm));
1176 return mm_init(mm, current, current_user_ns());
1179 static inline void __mmput(struct mm_struct *mm)
1181 VM_BUG_ON(atomic_read(&mm->mm_users));
1183 uprobe_clear_state(mm);
1186 khugepaged_exit(mm); /* must run before exit_mmap */
1188 mm_put_huge_zero_page(mm);
1189 set_mm_exe_file(mm, NULL);
1190 if (!list_empty(&mm->mmlist)) {
1191 spin_lock(&mmlist_lock);
1192 list_del(&mm->mmlist);
1193 spin_unlock(&mmlist_lock);
1196 module_put(mm->binfmt->module);
1201 * Decrement the use count and release all resources for an mm.
1203 void mmput(struct mm_struct *mm)
1207 if (atomic_dec_and_test(&mm->mm_users))
1210 EXPORT_SYMBOL_GPL(mmput);
1213 static void mmput_async_fn(struct work_struct *work)
1215 struct mm_struct *mm = container_of(work, struct mm_struct,
1221 void mmput_async(struct mm_struct *mm)
1223 if (atomic_dec_and_test(&mm->mm_users)) {
1224 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1225 schedule_work(&mm->async_put_work);
1231 * set_mm_exe_file - change a reference to the mm's executable file
1233 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1235 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1236 * invocations: in mmput() nobody alive left, in execve task is single
1239 * Can only fail if new_exe_file != NULL.
1241 int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1243 struct file *old_exe_file;
1246 * It is safe to dereference the exe_file without RCU as
1247 * this function is only called if nobody else can access
1248 * this mm -- see comment above for justification.
1250 old_exe_file = rcu_dereference_raw(mm->exe_file);
1254 * We expect the caller (i.e., sys_execve) to already denied
1255 * write access, so this is unlikely to fail.
1257 if (unlikely(deny_write_access(new_exe_file)))
1259 get_file(new_exe_file);
1261 rcu_assign_pointer(mm->exe_file, new_exe_file);
1263 allow_write_access(old_exe_file);
1270 * replace_mm_exe_file - replace a reference to the mm's executable file
1272 * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1273 * dealing with concurrent invocation and without grabbing the mmap lock in
1276 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1278 int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1280 struct vm_area_struct *vma;
1281 struct file *old_exe_file;
1284 /* Forbid mm->exe_file change if old file still mapped. */
1285 old_exe_file = get_mm_exe_file(mm);
1288 for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) {
1291 if (path_equal(&vma->vm_file->f_path,
1292 &old_exe_file->f_path))
1295 mmap_read_unlock(mm);
1301 /* set the new file, lockless */
1302 ret = deny_write_access(new_exe_file);
1305 get_file(new_exe_file);
1307 old_exe_file = xchg(&mm->exe_file, new_exe_file);
1310 * Don't race with dup_mmap() getting the file and disallowing
1311 * write access while someone might open the file writable.
1314 allow_write_access(old_exe_file);
1316 mmap_read_unlock(mm);
1322 * get_mm_exe_file - acquire a reference to the mm's executable file
1324 * Returns %NULL if mm has no associated executable file.
1325 * User must release file via fput().
1327 struct file *get_mm_exe_file(struct mm_struct *mm)
1329 struct file *exe_file;
1332 exe_file = rcu_dereference(mm->exe_file);
1333 if (exe_file && !get_file_rcu(exe_file))
1340 * get_task_exe_file - acquire a reference to the task's executable file
1342 * Returns %NULL if task's mm (if any) has no associated executable file or
1343 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1344 * User must release file via fput().
1346 struct file *get_task_exe_file(struct task_struct *task)
1348 struct file *exe_file = NULL;
1349 struct mm_struct *mm;
1354 if (!(task->flags & PF_KTHREAD))
1355 exe_file = get_mm_exe_file(mm);
1362 * get_task_mm - acquire a reference to the task's mm
1364 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1365 * this kernel workthread has transiently adopted a user mm with use_mm,
1366 * to do its AIO) is not set and if so returns a reference to it, after
1367 * bumping up the use count. User must release the mm via mmput()
1368 * after use. Typically used by /proc and ptrace.
1370 struct mm_struct *get_task_mm(struct task_struct *task)
1372 struct mm_struct *mm;
1377 if (task->flags & PF_KTHREAD)
1385 EXPORT_SYMBOL_GPL(get_task_mm);
1387 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1389 struct mm_struct *mm;
1392 err = down_read_killable(&task->signal->exec_update_lock);
1394 return ERR_PTR(err);
1396 mm = get_task_mm(task);
1397 if (mm && mm != current->mm &&
1398 !ptrace_may_access(task, mode)) {
1400 mm = ERR_PTR(-EACCES);
1402 up_read(&task->signal->exec_update_lock);
1407 static void complete_vfork_done(struct task_struct *tsk)
1409 struct completion *vfork;
1412 vfork = tsk->vfork_done;
1413 if (likely(vfork)) {
1414 tsk->vfork_done = NULL;
1420 static int wait_for_vfork_done(struct task_struct *child,
1421 struct completion *vfork)
1425 freezer_do_not_count();
1426 cgroup_enter_frozen();
1427 killed = wait_for_completion_killable(vfork);
1428 cgroup_leave_frozen(false);
1433 child->vfork_done = NULL;
1437 put_task_struct(child);
1441 /* Please note the differences between mmput and mm_release.
1442 * mmput is called whenever we stop holding onto a mm_struct,
1443 * error success whatever.
1445 * mm_release is called after a mm_struct has been removed
1446 * from the current process.
1448 * This difference is important for error handling, when we
1449 * only half set up a mm_struct for a new process and need to restore
1450 * the old one. Because we mmput the new mm_struct before
1451 * restoring the old one. . .
1452 * Eric Biederman 10 January 1998
1454 static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1456 uprobe_free_utask(tsk);
1458 /* Get rid of any cached register state */
1459 deactivate_mm(tsk, mm);
1462 * Signal userspace if we're not exiting with a core dump
1463 * because we want to leave the value intact for debugging
1466 if (tsk->clear_child_tid) {
1467 if (atomic_read(&mm->mm_users) > 1) {
1469 * We don't check the error code - if userspace has
1470 * not set up a proper pointer then tough luck.
1472 put_user(0, tsk->clear_child_tid);
1473 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1474 1, NULL, NULL, 0, 0);
1476 tsk->clear_child_tid = NULL;
1480 * All done, finally we can wake up parent and return this mm to him.
1481 * Also kthread_stop() uses this completion for synchronization.
1483 if (tsk->vfork_done)
1484 complete_vfork_done(tsk);
1487 void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1489 futex_exit_release(tsk);
1490 mm_release(tsk, mm);
1493 void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1495 futex_exec_release(tsk);
1496 mm_release(tsk, mm);
1500 * dup_mm() - duplicates an existing mm structure
1501 * @tsk: the task_struct with which the new mm will be associated.
1502 * @oldmm: the mm to duplicate.
1504 * Allocates a new mm structure and duplicates the provided @oldmm structure
1507 * Return: the duplicated mm or NULL on failure.
1509 static struct mm_struct *dup_mm(struct task_struct *tsk,
1510 struct mm_struct *oldmm)
1512 struct mm_struct *mm;
1519 memcpy(mm, oldmm, sizeof(*mm));
1521 if (!mm_init(mm, tsk, mm->user_ns))
1524 err = dup_mmap(mm, oldmm);
1528 mm->hiwater_rss = get_mm_rss(mm);
1529 mm->hiwater_vm = mm->total_vm;
1531 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1537 /* don't put binfmt in mmput, we haven't got module yet */
1539 mm_init_owner(mm, NULL);
1546 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1548 struct mm_struct *mm, *oldmm;
1550 tsk->min_flt = tsk->maj_flt = 0;
1551 tsk->nvcsw = tsk->nivcsw = 0;
1552 #ifdef CONFIG_DETECT_HUNG_TASK
1553 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1554 tsk->last_switch_time = 0;
1558 tsk->active_mm = NULL;
1561 * Are we cloning a kernel thread?
1563 * We need to steal a active VM for that..
1565 oldmm = current->mm;
1569 /* initialize the new vmacache entries */
1570 vmacache_flush(tsk);
1572 if (clone_flags & CLONE_VM) {
1576 mm = dup_mm(tsk, current->mm);
1582 tsk->active_mm = mm;
1586 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1588 struct fs_struct *fs = current->fs;
1589 if (clone_flags & CLONE_FS) {
1590 /* tsk->fs is already what we want */
1591 spin_lock(&fs->lock);
1593 spin_unlock(&fs->lock);
1597 spin_unlock(&fs->lock);
1600 tsk->fs = copy_fs_struct(fs);
1606 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1608 struct files_struct *oldf, *newf;
1612 * A background process may not have any files ...
1614 oldf = current->files;
1618 if (clone_flags & CLONE_FILES) {
1619 atomic_inc(&oldf->count);
1623 newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1633 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1635 struct sighand_struct *sig;
1637 if (clone_flags & CLONE_SIGHAND) {
1638 refcount_inc(¤t->sighand->count);
1641 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1642 RCU_INIT_POINTER(tsk->sighand, sig);
1646 refcount_set(&sig->count, 1);
1647 spin_lock_irq(¤t->sighand->siglock);
1648 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1649 spin_unlock_irq(¤t->sighand->siglock);
1651 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1652 if (clone_flags & CLONE_CLEAR_SIGHAND)
1653 flush_signal_handlers(tsk, 0);
1658 void __cleanup_sighand(struct sighand_struct *sighand)
1660 if (refcount_dec_and_test(&sighand->count)) {
1661 signalfd_cleanup(sighand);
1663 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1664 * without an RCU grace period, see __lock_task_sighand().
1666 kmem_cache_free(sighand_cachep, sighand);
1671 * Initialize POSIX timer handling for a thread group.
1673 static void posix_cpu_timers_init_group(struct signal_struct *sig)
1675 struct posix_cputimers *pct = &sig->posix_cputimers;
1676 unsigned long cpu_limit;
1678 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1679 posix_cputimers_group_init(pct, cpu_limit);
1682 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1684 struct signal_struct *sig;
1686 if (clone_flags & CLONE_THREAD)
1689 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1694 sig->nr_threads = 1;
1695 atomic_set(&sig->live, 1);
1696 refcount_set(&sig->sigcnt, 1);
1698 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1699 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1700 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1702 init_waitqueue_head(&sig->wait_chldexit);
1703 sig->curr_target = tsk;
1704 init_sigpending(&sig->shared_pending);
1705 INIT_HLIST_HEAD(&sig->multiprocess);
1706 seqlock_init(&sig->stats_lock);
1707 prev_cputime_init(&sig->prev_cputime);
1709 #ifdef CONFIG_POSIX_TIMERS
1710 INIT_LIST_HEAD(&sig->posix_timers);
1711 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1712 sig->real_timer.function = it_real_fn;
1715 task_lock(current->group_leader);
1716 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1717 task_unlock(current->group_leader);
1719 posix_cpu_timers_init_group(sig);
1721 tty_audit_fork(sig);
1722 sched_autogroup_fork(sig);
1724 sig->oom_score_adj = current->signal->oom_score_adj;
1725 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1727 mutex_init(&sig->cred_guard_mutex);
1728 init_rwsem(&sig->exec_update_lock);
1733 static void copy_seccomp(struct task_struct *p)
1735 #ifdef CONFIG_SECCOMP
1737 * Must be called with sighand->lock held, which is common to
1738 * all threads in the group. Holding cred_guard_mutex is not
1739 * needed because this new task is not yet running and cannot
1742 assert_spin_locked(¤t->sighand->siglock);
1744 /* Ref-count the new filter user, and assign it. */
1745 get_seccomp_filter(current);
1746 p->seccomp = current->seccomp;
1749 * Explicitly enable no_new_privs here in case it got set
1750 * between the task_struct being duplicated and holding the
1751 * sighand lock. The seccomp state and nnp must be in sync.
1753 if (task_no_new_privs(current))
1754 task_set_no_new_privs(p);
1757 * If the parent gained a seccomp mode after copying thread
1758 * flags and between before we held the sighand lock, we have
1759 * to manually enable the seccomp thread flag here.
1761 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1762 set_task_syscall_work(p, SECCOMP);
1766 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1768 current->clear_child_tid = tidptr;
1770 return task_pid_vnr(current);
1773 static void rt_mutex_init_task(struct task_struct *p)
1775 raw_spin_lock_init(&p->pi_lock);
1776 #ifdef CONFIG_RT_MUTEXES
1777 p->pi_waiters = RB_ROOT_CACHED;
1778 p->pi_top_task = NULL;
1779 p->pi_blocked_on = NULL;
1783 static inline void init_task_pid_links(struct task_struct *task)
1787 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1788 INIT_HLIST_NODE(&task->pid_links[type]);
1792 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1794 if (type == PIDTYPE_PID)
1795 task->thread_pid = pid;
1797 task->signal->pids[type] = pid;
1800 static inline void rcu_copy_process(struct task_struct *p)
1802 #ifdef CONFIG_PREEMPT_RCU
1803 p->rcu_read_lock_nesting = 0;
1804 p->rcu_read_unlock_special.s = 0;
1805 p->rcu_blocked_node = NULL;
1806 INIT_LIST_HEAD(&p->rcu_node_entry);
1807 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1808 #ifdef CONFIG_TASKS_RCU
1809 p->rcu_tasks_holdout = false;
1810 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1811 p->rcu_tasks_idle_cpu = -1;
1812 #endif /* #ifdef CONFIG_TASKS_RCU */
1813 #ifdef CONFIG_TASKS_TRACE_RCU
1814 p->trc_reader_nesting = 0;
1815 p->trc_reader_special.s = 0;
1816 INIT_LIST_HEAD(&p->trc_holdout_list);
1817 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1820 struct pid *pidfd_pid(const struct file *file)
1822 if (file->f_op == &pidfd_fops)
1823 return file->private_data;
1825 return ERR_PTR(-EBADF);
1828 static int pidfd_release(struct inode *inode, struct file *file)
1830 struct pid *pid = file->private_data;
1832 file->private_data = NULL;
1837 #ifdef CONFIG_PROC_FS
1839 * pidfd_show_fdinfo - print information about a pidfd
1840 * @m: proc fdinfo file
1841 * @f: file referencing a pidfd
1844 * This function will print the pid that a given pidfd refers to in the
1845 * pid namespace of the procfs instance.
1846 * If the pid namespace of the process is not a descendant of the pid
1847 * namespace of the procfs instance 0 will be shown as its pid. This is
1848 * similar to calling getppid() on a process whose parent is outside of
1849 * its pid namespace.
1852 * If pid namespaces are supported then this function will also print
1853 * the pid of a given pidfd refers to for all descendant pid namespaces
1854 * starting from the current pid namespace of the instance, i.e. the
1855 * Pid field and the first entry in the NSpid field will be identical.
1856 * If the pid namespace of the process is not a descendant of the pid
1857 * namespace of the procfs instance 0 will be shown as its first NSpid
1858 * entry and no others will be shown.
1859 * Note that this differs from the Pid and NSpid fields in
1860 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1861 * the pid namespace of the procfs instance. The difference becomes
1862 * obvious when sending around a pidfd between pid namespaces from a
1863 * different branch of the tree, i.e. where no ancestral relation is
1864 * present between the pid namespaces:
1865 * - create two new pid namespaces ns1 and ns2 in the initial pid
1866 * namespace (also take care to create new mount namespaces in the
1867 * new pid namespace and mount procfs)
1868 * - create a process with a pidfd in ns1
1869 * - send pidfd from ns1 to ns2
1870 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1871 * have exactly one entry, which is 0
1873 static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
1875 struct pid *pid = f->private_data;
1876 struct pid_namespace *ns;
1879 if (likely(pid_has_task(pid, PIDTYPE_PID))) {
1880 ns = proc_pid_ns(file_inode(m->file)->i_sb);
1881 nr = pid_nr_ns(pid, ns);
1884 seq_put_decimal_ll(m, "Pid:\t", nr);
1886 #ifdef CONFIG_PID_NS
1887 seq_put_decimal_ll(m, "\nNSpid:\t", nr);
1891 /* If nr is non-zero it means that 'pid' is valid and that
1892 * ns, i.e. the pid namespace associated with the procfs
1893 * instance, is in the pid namespace hierarchy of pid.
1894 * Start at one below the already printed level.
1896 for (i = ns->level + 1; i <= pid->level; i++)
1897 seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
1905 * Poll support for process exit notification.
1907 static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
1909 struct pid *pid = file->private_data;
1910 __poll_t poll_flags = 0;
1912 poll_wait(file, &pid->wait_pidfd, pts);
1915 * Inform pollers only when the whole thread group exits.
1916 * If the thread group leader exits before all other threads in the
1917 * group, then poll(2) should block, similar to the wait(2) family.
1919 if (thread_group_exited(pid))
1920 poll_flags = EPOLLIN | EPOLLRDNORM;
1925 const struct file_operations pidfd_fops = {
1926 .release = pidfd_release,
1928 #ifdef CONFIG_PROC_FS
1929 .show_fdinfo = pidfd_show_fdinfo,
1933 static void __delayed_free_task(struct rcu_head *rhp)
1935 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1940 static __always_inline void delayed_free_task(struct task_struct *tsk)
1942 if (IS_ENABLED(CONFIG_MEMCG))
1943 call_rcu(&tsk->rcu, __delayed_free_task);
1948 static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1950 /* Skip if kernel thread */
1954 /* Skip if spawning a thread or using vfork */
1955 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1958 /* We need to synchronize with __set_oom_adj */
1959 mutex_lock(&oom_adj_mutex);
1960 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1961 /* Update the values in case they were changed after copy_signal */
1962 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1963 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1964 mutex_unlock(&oom_adj_mutex);
1968 * This creates a new process as a copy of the old one,
1969 * but does not actually start it yet.
1971 * It copies the registers, and all the appropriate
1972 * parts of the process environment (as per the clone
1973 * flags). The actual kick-off is left to the caller.
1975 static __latent_entropy struct task_struct *copy_process(
1979 struct kernel_clone_args *args)
1981 int pidfd = -1, retval;
1982 struct task_struct *p;
1983 struct multiprocess_signals delayed;
1984 struct file *pidfile = NULL;
1985 u64 clone_flags = args->flags;
1986 struct nsproxy *nsp = current->nsproxy;
1989 * Don't allow sharing the root directory with processes in a different
1992 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1993 return ERR_PTR(-EINVAL);
1995 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1996 return ERR_PTR(-EINVAL);
1999 * Thread groups must share signals as well, and detached threads
2000 * can only be started up within the thread group.
2002 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2003 return ERR_PTR(-EINVAL);
2006 * Shared signal handlers imply shared VM. By way of the above,
2007 * thread groups also imply shared VM. Blocking this case allows
2008 * for various simplifications in other code.
2010 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2011 return ERR_PTR(-EINVAL);
2014 * Siblings of global init remain as zombies on exit since they are
2015 * not reaped by their parent (swapper). To solve this and to avoid
2016 * multi-rooted process trees, prevent global and container-inits
2017 * from creating siblings.
2019 if ((clone_flags & CLONE_PARENT) &&
2020 current->signal->flags & SIGNAL_UNKILLABLE)
2021 return ERR_PTR(-EINVAL);
2024 * If the new process will be in a different pid or user namespace
2025 * do not allow it to share a thread group with the forking task.
2027 if (clone_flags & CLONE_THREAD) {
2028 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2029 (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2030 return ERR_PTR(-EINVAL);
2034 * If the new process will be in a different time namespace
2035 * do not allow it to share VM or a thread group with the forking task.
2037 if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
2038 if (nsp->time_ns != nsp->time_ns_for_children)
2039 return ERR_PTR(-EINVAL);
2042 if (clone_flags & CLONE_PIDFD) {
2044 * - CLONE_DETACHED is blocked so that we can potentially
2045 * reuse it later for CLONE_PIDFD.
2046 * - CLONE_THREAD is blocked until someone really needs it.
2048 if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
2049 return ERR_PTR(-EINVAL);
2053 * Force any signals received before this point to be delivered
2054 * before the fork happens. Collect up signals sent to multiple
2055 * processes that happen during the fork and delay them so that
2056 * they appear to happen after the fork.
2058 sigemptyset(&delayed.signal);
2059 INIT_HLIST_NODE(&delayed.node);
2061 spin_lock_irq(¤t->sighand->siglock);
2062 if (!(clone_flags & CLONE_THREAD))
2063 hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2064 recalc_sigpending();
2065 spin_unlock_irq(¤t->sighand->siglock);
2066 retval = -ERESTARTNOINTR;
2067 if (task_sigpending(current))
2071 p = dup_task_struct(current, node);
2074 if (args->io_thread) {
2076 * Mark us an IO worker, and block any signal that isn't
2079 p->flags |= PF_IO_WORKER;
2080 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2083 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2085 * Clear TID on mm_release()?
2087 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2089 ftrace_graph_init_task(p);
2091 rt_mutex_init_task(p);
2093 lockdep_assert_irqs_enabled();
2094 #ifdef CONFIG_PROVE_LOCKING
2095 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2097 retval = copy_creds(p, clone_flags);
2102 if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2103 if (p->real_cred->user != INIT_USER &&
2104 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2105 goto bad_fork_cleanup_count;
2107 current->flags &= ~PF_NPROC_EXCEEDED;
2110 * If multiple threads are within copy_process(), then this check
2111 * triggers too late. This doesn't hurt, the check is only there
2112 * to stop root fork bombs.
2115 if (data_race(nr_threads >= max_threads))
2116 goto bad_fork_cleanup_count;
2118 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2119 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2120 p->flags |= PF_FORKNOEXEC;
2121 INIT_LIST_HEAD(&p->children);
2122 INIT_LIST_HEAD(&p->sibling);
2123 rcu_copy_process(p);
2124 p->vfork_done = NULL;
2125 spin_lock_init(&p->alloc_lock);
2127 init_sigpending(&p->pending);
2129 p->utime = p->stime = p->gtime = 0;
2130 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2131 p->utimescaled = p->stimescaled = 0;
2133 prev_cputime_init(&p->prev_cputime);
2135 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2136 seqcount_init(&p->vtime.seqcount);
2137 p->vtime.starttime = 0;
2138 p->vtime.state = VTIME_INACTIVE;
2141 #ifdef CONFIG_IO_URING
2145 #if defined(SPLIT_RSS_COUNTING)
2146 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2149 p->default_timer_slack_ns = current->timer_slack_ns;
2155 task_io_accounting_init(&p->ioac);
2156 acct_clear_integrals(p);
2158 posix_cputimers_init(&p->posix_cputimers);
2160 p->io_context = NULL;
2161 audit_set_context(p, NULL);
2163 if (p->flags & PF_KTHREAD) {
2164 if (!set_kthread_struct(p))
2165 goto bad_fork_cleanup_delayacct;
2168 p->mempolicy = mpol_dup(p->mempolicy);
2169 if (IS_ERR(p->mempolicy)) {
2170 retval = PTR_ERR(p->mempolicy);
2171 p->mempolicy = NULL;
2172 goto bad_fork_cleanup_delayacct;
2175 #ifdef CONFIG_CPUSETS
2176 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2177 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2178 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2180 #ifdef CONFIG_TRACE_IRQFLAGS
2181 memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2182 p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2183 p->irqtrace.softirq_enable_ip = _THIS_IP_;
2184 p->softirqs_enabled = 1;
2185 p->softirq_context = 0;
2188 p->pagefault_disabled = 0;
2190 #ifdef CONFIG_LOCKDEP
2191 lockdep_init_task(p);
2194 #ifdef CONFIG_DEBUG_MUTEXES
2195 p->blocked_on = NULL; /* not blocked yet */
2197 #ifdef CONFIG_BCACHE
2198 p->sequential_io = 0;
2199 p->sequential_io_avg = 0;
2201 #ifdef CONFIG_BPF_SYSCALL
2202 RCU_INIT_POINTER(p->bpf_storage, NULL);
2206 /* Perform scheduler related setup. Assign this task to a CPU. */
2207 retval = sched_fork(clone_flags, p);
2209 goto bad_fork_cleanup_policy;
2211 retval = perf_event_init_task(p, clone_flags);
2213 goto bad_fork_cleanup_policy;
2214 retval = audit_alloc(p);
2216 goto bad_fork_cleanup_perf;
2217 /* copy all the process information */
2219 retval = security_task_alloc(p, clone_flags);
2221 goto bad_fork_cleanup_audit;
2222 retval = copy_semundo(clone_flags, p);
2224 goto bad_fork_cleanup_security;
2225 retval = copy_files(clone_flags, p);
2227 goto bad_fork_cleanup_semundo;
2228 retval = copy_fs(clone_flags, p);
2230 goto bad_fork_cleanup_files;
2231 retval = copy_sighand(clone_flags, p);
2233 goto bad_fork_cleanup_fs;
2234 retval = copy_signal(clone_flags, p);
2236 goto bad_fork_cleanup_sighand;
2237 retval = copy_mm(clone_flags, p);
2239 goto bad_fork_cleanup_signal;
2240 retval = copy_namespaces(clone_flags, p);
2242 goto bad_fork_cleanup_mm;
2243 retval = copy_io(clone_flags, p);
2245 goto bad_fork_cleanup_namespaces;
2246 retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls);
2248 goto bad_fork_cleanup_io;
2250 stackleak_task_init(p);
2252 if (pid != &init_struct_pid) {
2253 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2254 args->set_tid_size);
2256 retval = PTR_ERR(pid);
2257 goto bad_fork_cleanup_thread;
2262 * This has to happen after we've potentially unshared the file
2263 * descriptor table (so that the pidfd doesn't leak into the child
2264 * if the fd table isn't shared).
2266 if (clone_flags & CLONE_PIDFD) {
2267 retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2269 goto bad_fork_free_pid;
2273 pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2274 O_RDWR | O_CLOEXEC);
2275 if (IS_ERR(pidfile)) {
2276 put_unused_fd(pidfd);
2277 retval = PTR_ERR(pidfile);
2278 goto bad_fork_free_pid;
2280 get_pid(pid); /* held by pidfile now */
2282 retval = put_user(pidfd, args->pidfd);
2284 goto bad_fork_put_pidfd;
2293 * sigaltstack should be cleared when sharing the same VM
2295 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2299 * Syscall tracing and stepping should be turned off in the
2300 * child regardless of CLONE_PTRACE.
2302 user_disable_single_step(p);
2303 clear_task_syscall_work(p, SYSCALL_TRACE);
2304 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2305 clear_task_syscall_work(p, SYSCALL_EMU);
2307 clear_tsk_latency_tracing(p);
2309 /* ok, now we should be set up.. */
2310 p->pid = pid_nr(pid);
2311 if (clone_flags & CLONE_THREAD) {
2312 p->group_leader = current->group_leader;
2313 p->tgid = current->tgid;
2315 p->group_leader = p;
2320 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2321 p->dirty_paused_when = 0;
2323 p->pdeath_signal = 0;
2324 INIT_LIST_HEAD(&p->thread_group);
2325 p->task_works = NULL;
2326 clear_posix_cputimers_work(p);
2328 #ifdef CONFIG_KRETPROBES
2329 p->kretprobe_instances.first = NULL;
2331 #ifdef CONFIG_RETHOOK
2332 p->rethooks.first = NULL;
2336 * Ensure that the cgroup subsystem policies allow the new process to be
2337 * forked. It should be noted that the new process's css_set can be changed
2338 * between here and cgroup_post_fork() if an organisation operation is in
2341 retval = cgroup_can_fork(p, args);
2343 goto bad_fork_put_pidfd;
2346 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2347 * the new task on the correct runqueue. All this *before* the task
2350 * This isn't part of ->can_fork() because while the re-cloning is
2351 * cgroup specific, it unconditionally needs to place the task on a
2354 sched_cgroup_fork(p, args);
2357 * From this point on we must avoid any synchronous user-space
2358 * communication until we take the tasklist-lock. In particular, we do
2359 * not want user-space to be able to predict the process start-time by
2360 * stalling fork(2) after we recorded the start_time but before it is
2361 * visible to the system.
2364 p->start_time = ktime_get_ns();
2365 p->start_boottime = ktime_get_boottime_ns();
2368 * Make it visible to the rest of the system, but dont wake it up yet.
2369 * Need tasklist lock for parent etc handling!
2371 write_lock_irq(&tasklist_lock);
2373 /* CLONE_PARENT re-uses the old parent */
2374 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2375 p->real_parent = current->real_parent;
2376 p->parent_exec_id = current->parent_exec_id;
2377 if (clone_flags & CLONE_THREAD)
2378 p->exit_signal = -1;
2380 p->exit_signal = current->group_leader->exit_signal;
2382 p->real_parent = current;
2383 p->parent_exec_id = current->self_exec_id;
2384 p->exit_signal = args->exit_signal;
2387 klp_copy_process(p);
2391 spin_lock(¤t->sighand->siglock);
2394 * Copy seccomp details explicitly here, in case they were changed
2395 * before holding sighand lock.
2399 rseq_fork(p, clone_flags);
2401 /* Don't start children in a dying pid namespace */
2402 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2404 goto bad_fork_cancel_cgroup;
2407 /* Let kill terminate clone/fork in the middle */
2408 if (fatal_signal_pending(current)) {
2410 goto bad_fork_cancel_cgroup;
2413 init_task_pid_links(p);
2414 if (likely(p->pid)) {
2415 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2417 init_task_pid(p, PIDTYPE_PID, pid);
2418 if (thread_group_leader(p)) {
2419 init_task_pid(p, PIDTYPE_TGID, pid);
2420 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2421 init_task_pid(p, PIDTYPE_SID, task_session(current));
2423 if (is_child_reaper(pid)) {
2424 ns_of_pid(pid)->child_reaper = p;
2425 p->signal->flags |= SIGNAL_UNKILLABLE;
2427 p->signal->shared_pending.signal = delayed.signal;
2428 p->signal->tty = tty_kref_get(current->signal->tty);
2430 * Inherit has_child_subreaper flag under the same
2431 * tasklist_lock with adding child to the process tree
2432 * for propagate_has_child_subreaper optimization.
2434 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2435 p->real_parent->signal->is_child_subreaper;
2436 list_add_tail(&p->sibling, &p->real_parent->children);
2437 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2438 attach_pid(p, PIDTYPE_TGID);
2439 attach_pid(p, PIDTYPE_PGID);
2440 attach_pid(p, PIDTYPE_SID);
2441 __this_cpu_inc(process_counts);
2443 current->signal->nr_threads++;
2444 atomic_inc(¤t->signal->live);
2445 refcount_inc(¤t->signal->sigcnt);
2446 task_join_group_stop(p);
2447 list_add_tail_rcu(&p->thread_group,
2448 &p->group_leader->thread_group);
2449 list_add_tail_rcu(&p->thread_node,
2450 &p->signal->thread_head);
2452 attach_pid(p, PIDTYPE_PID);
2456 hlist_del_init(&delayed.node);
2457 spin_unlock(¤t->sighand->siglock);
2458 syscall_tracepoint_update(p);
2459 write_unlock_irq(&tasklist_lock);
2462 fd_install(pidfd, pidfile);
2464 proc_fork_connector(p);
2466 cgroup_post_fork(p, args);
2469 trace_task_newtask(p, clone_flags);
2470 uprobe_copy_process(p, clone_flags);
2472 copy_oom_score_adj(clone_flags, p);
2476 bad_fork_cancel_cgroup:
2478 spin_unlock(¤t->sighand->siglock);
2479 write_unlock_irq(&tasklist_lock);
2480 cgroup_cancel_fork(p, args);
2482 if (clone_flags & CLONE_PIDFD) {
2484 put_unused_fd(pidfd);
2487 if (pid != &init_struct_pid)
2489 bad_fork_cleanup_thread:
2491 bad_fork_cleanup_io:
2494 bad_fork_cleanup_namespaces:
2495 exit_task_namespaces(p);
2496 bad_fork_cleanup_mm:
2498 mm_clear_owner(p->mm, p);
2501 bad_fork_cleanup_signal:
2502 if (!(clone_flags & CLONE_THREAD))
2503 free_signal_struct(p->signal);
2504 bad_fork_cleanup_sighand:
2505 __cleanup_sighand(p->sighand);
2506 bad_fork_cleanup_fs:
2507 exit_fs(p); /* blocking */
2508 bad_fork_cleanup_files:
2509 exit_files(p); /* blocking */
2510 bad_fork_cleanup_semundo:
2512 bad_fork_cleanup_security:
2513 security_task_free(p);
2514 bad_fork_cleanup_audit:
2516 bad_fork_cleanup_perf:
2517 perf_event_free_task(p);
2518 bad_fork_cleanup_policy:
2519 lockdep_free_task(p);
2521 mpol_put(p->mempolicy);
2523 bad_fork_cleanup_delayacct:
2524 delayacct_tsk_free(p);
2525 bad_fork_cleanup_count:
2526 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2529 WRITE_ONCE(p->__state, TASK_DEAD);
2530 exit_task_stack_account(p);
2532 delayed_free_task(p);
2534 spin_lock_irq(¤t->sighand->siglock);
2535 hlist_del_init(&delayed.node);
2536 spin_unlock_irq(¤t->sighand->siglock);
2537 return ERR_PTR(retval);
2540 static inline void init_idle_pids(struct task_struct *idle)
2544 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2545 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2546 init_task_pid(idle, type, &init_struct_pid);
2550 struct task_struct * __init fork_idle(int cpu)
2552 struct task_struct *task;
2553 struct kernel_clone_args args = {
2557 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2558 if (!IS_ERR(task)) {
2559 init_idle_pids(task);
2560 init_idle(task, cpu);
2566 struct mm_struct *copy_init_mm(void)
2568 return dup_mm(NULL, &init_mm);
2572 * This is like kernel_clone(), but shaved down and tailored to just
2573 * creating io_uring workers. It returns a created task, or an error pointer.
2574 * The returned task is inactive, and the caller must fire it up through
2575 * wake_up_new_task(p). All signals are blocked in the created task.
2577 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2579 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2581 struct kernel_clone_args args = {
2582 .flags = ((lower_32_bits(flags) | CLONE_VM |
2583 CLONE_UNTRACED) & ~CSIGNAL),
2584 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2585 .stack = (unsigned long)fn,
2586 .stack_size = (unsigned long)arg,
2590 return copy_process(NULL, 0, node, &args);
2594 * Ok, this is the main fork-routine.
2596 * It copies the process, and if successful kick-starts
2597 * it and waits for it to finish using the VM if required.
2599 * args->exit_signal is expected to be checked for sanity by the caller.
2601 pid_t kernel_clone(struct kernel_clone_args *args)
2603 u64 clone_flags = args->flags;
2604 struct completion vfork;
2606 struct task_struct *p;
2611 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2612 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2613 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2614 * field in struct clone_args and it still doesn't make sense to have
2615 * them both point at the same memory location. Performing this check
2616 * here has the advantage that we don't need to have a separate helper
2617 * to check for legacy clone().
2619 if ((args->flags & CLONE_PIDFD) &&
2620 (args->flags & CLONE_PARENT_SETTID) &&
2621 (args->pidfd == args->parent_tid))
2625 * Determine whether and which event to report to ptracer. When
2626 * called from kernel_thread or CLONE_UNTRACED is explicitly
2627 * requested, no event is reported; otherwise, report if the event
2628 * for the type of forking is enabled.
2630 if (!(clone_flags & CLONE_UNTRACED)) {
2631 if (clone_flags & CLONE_VFORK)
2632 trace = PTRACE_EVENT_VFORK;
2633 else if (args->exit_signal != SIGCHLD)
2634 trace = PTRACE_EVENT_CLONE;
2636 trace = PTRACE_EVENT_FORK;
2638 if (likely(!ptrace_event_enabled(current, trace)))
2642 p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2643 add_latent_entropy();
2649 * Do this prior waking up the new thread - the thread pointer
2650 * might get invalid after that point, if the thread exits quickly.
2652 trace_sched_process_fork(current, p);
2654 pid = get_task_pid(p, PIDTYPE_PID);
2657 if (clone_flags & CLONE_PARENT_SETTID)
2658 put_user(nr, args->parent_tid);
2660 if (clone_flags & CLONE_VFORK) {
2661 p->vfork_done = &vfork;
2662 init_completion(&vfork);
2666 wake_up_new_task(p);
2668 /* forking complete and child started to run, tell ptracer */
2669 if (unlikely(trace))
2670 ptrace_event_pid(trace, pid);
2672 if (clone_flags & CLONE_VFORK) {
2673 if (!wait_for_vfork_done(p, &vfork))
2674 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2682 * Create a kernel thread.
2684 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2686 struct kernel_clone_args args = {
2687 .flags = ((lower_32_bits(flags) | CLONE_VM |
2688 CLONE_UNTRACED) & ~CSIGNAL),
2689 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2690 .stack = (unsigned long)fn,
2691 .stack_size = (unsigned long)arg,
2694 return kernel_clone(&args);
2697 #ifdef __ARCH_WANT_SYS_FORK
2698 SYSCALL_DEFINE0(fork)
2701 struct kernel_clone_args args = {
2702 .exit_signal = SIGCHLD,
2705 return kernel_clone(&args);
2707 /* can not support in nommu mode */
2713 #ifdef __ARCH_WANT_SYS_VFORK
2714 SYSCALL_DEFINE0(vfork)
2716 struct kernel_clone_args args = {
2717 .flags = CLONE_VFORK | CLONE_VM,
2718 .exit_signal = SIGCHLD,
2721 return kernel_clone(&args);
2725 #ifdef __ARCH_WANT_SYS_CLONE
2726 #ifdef CONFIG_CLONE_BACKWARDS
2727 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2728 int __user *, parent_tidptr,
2730 int __user *, child_tidptr)
2731 #elif defined(CONFIG_CLONE_BACKWARDS2)
2732 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2733 int __user *, parent_tidptr,
2734 int __user *, child_tidptr,
2736 #elif defined(CONFIG_CLONE_BACKWARDS3)
2737 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2739 int __user *, parent_tidptr,
2740 int __user *, child_tidptr,
2743 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2744 int __user *, parent_tidptr,
2745 int __user *, child_tidptr,
2749 struct kernel_clone_args args = {
2750 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2751 .pidfd = parent_tidptr,
2752 .child_tid = child_tidptr,
2753 .parent_tid = parent_tidptr,
2754 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2759 return kernel_clone(&args);
2763 #ifdef __ARCH_WANT_SYS_CLONE3
2765 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2766 struct clone_args __user *uargs,
2770 struct clone_args args;
2771 pid_t *kset_tid = kargs->set_tid;
2773 BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2774 CLONE_ARGS_SIZE_VER0);
2775 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2776 CLONE_ARGS_SIZE_VER1);
2777 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2778 CLONE_ARGS_SIZE_VER2);
2779 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2781 if (unlikely(usize > PAGE_SIZE))
2783 if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2786 err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2790 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2793 if (unlikely(!args.set_tid && args.set_tid_size > 0))
2796 if (unlikely(args.set_tid && args.set_tid_size == 0))
2800 * Verify that higher 32bits of exit_signal are unset and that
2801 * it is a valid signal
2803 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2804 !valid_signal(args.exit_signal)))
2807 if ((args.flags & CLONE_INTO_CGROUP) &&
2808 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2811 *kargs = (struct kernel_clone_args){
2812 .flags = args.flags,
2813 .pidfd = u64_to_user_ptr(args.pidfd),
2814 .child_tid = u64_to_user_ptr(args.child_tid),
2815 .parent_tid = u64_to_user_ptr(args.parent_tid),
2816 .exit_signal = args.exit_signal,
2817 .stack = args.stack,
2818 .stack_size = args.stack_size,
2820 .set_tid_size = args.set_tid_size,
2821 .cgroup = args.cgroup,
2825 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
2826 (kargs->set_tid_size * sizeof(pid_t))))
2829 kargs->set_tid = kset_tid;
2835 * clone3_stack_valid - check and prepare stack
2836 * @kargs: kernel clone args
2838 * Verify that the stack arguments userspace gave us are sane.
2839 * In addition, set the stack direction for userspace since it's easy for us to
2842 static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
2844 if (kargs->stack == 0) {
2845 if (kargs->stack_size > 0)
2848 if (kargs->stack_size == 0)
2851 if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
2854 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2855 kargs->stack += kargs->stack_size;
2862 static bool clone3_args_valid(struct kernel_clone_args *kargs)
2864 /* Verify that no unknown flags are passed along. */
2866 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
2870 * - make the CLONE_DETACHED bit reusable for clone3
2871 * - make the CSIGNAL bits reusable for clone3
2873 if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
2876 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
2877 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
2880 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
2884 if (!clone3_stack_valid(kargs))
2891 * clone3 - create a new process with specific properties
2892 * @uargs: argument structure
2893 * @size: size of @uargs
2895 * clone3() is the extensible successor to clone()/clone2().
2896 * It takes a struct as argument that is versioned by its size.
2898 * Return: On success, a positive PID for the child process.
2899 * On error, a negative errno number.
2901 SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
2905 struct kernel_clone_args kargs;
2906 pid_t set_tid[MAX_PID_NS_LEVEL];
2908 kargs.set_tid = set_tid;
2910 err = copy_clone_args_from_user(&kargs, uargs, size);
2914 if (!clone3_args_valid(&kargs))
2917 return kernel_clone(&kargs);
2921 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2923 struct task_struct *leader, *parent, *child;
2926 read_lock(&tasklist_lock);
2927 leader = top = top->group_leader;
2929 for_each_thread(leader, parent) {
2930 list_for_each_entry(child, &parent->children, sibling) {
2931 res = visitor(child, data);
2943 if (leader != top) {
2945 parent = child->real_parent;
2946 leader = parent->group_leader;
2950 read_unlock(&tasklist_lock);
2953 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2954 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2957 static void sighand_ctor(void *data)
2959 struct sighand_struct *sighand = data;
2961 spin_lock_init(&sighand->siglock);
2962 init_waitqueue_head(&sighand->signalfd_wqh);
2965 void __init proc_caches_init(void)
2967 unsigned int mm_size;
2969 sighand_cachep = kmem_cache_create("sighand_cache",
2970 sizeof(struct sighand_struct), 0,
2971 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2972 SLAB_ACCOUNT, sighand_ctor);
2973 signal_cachep = kmem_cache_create("signal_cache",
2974 sizeof(struct signal_struct), 0,
2975 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2977 files_cachep = kmem_cache_create("files_cache",
2978 sizeof(struct files_struct), 0,
2979 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2981 fs_cachep = kmem_cache_create("fs_cache",
2982 sizeof(struct fs_struct), 0,
2983 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2987 * The mm_cpumask is located at the end of mm_struct, and is
2988 * dynamically sized based on the maximum CPU number this system
2989 * can have, taking hotplug into account (nr_cpu_ids).
2991 mm_size = sizeof(struct mm_struct) + cpumask_size();
2993 mm_cachep = kmem_cache_create_usercopy("mm_struct",
2994 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
2995 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2996 offsetof(struct mm_struct, saved_auxv),
2997 sizeof_field(struct mm_struct, saved_auxv),
2999 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
3001 nsproxy_cache_init();
3005 * Check constraints on flags passed to the unshare system call.
3007 static int check_unshare_flags(unsigned long unshare_flags)
3009 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3010 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3011 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3012 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3016 * Not implemented, but pretend it works if there is nothing
3017 * to unshare. Note that unsharing the address space or the
3018 * signal handlers also need to unshare the signal queues (aka
3021 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3022 if (!thread_group_empty(current))
3025 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3026 if (refcount_read(¤t->sighand->count) > 1)
3029 if (unshare_flags & CLONE_VM) {
3030 if (!current_is_single_threaded())
3038 * Unshare the filesystem structure if it is being shared
3040 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3042 struct fs_struct *fs = current->fs;
3044 if (!(unshare_flags & CLONE_FS) || !fs)
3047 /* don't need lock here; in the worst case we'll do useless copy */
3051 *new_fsp = copy_fs_struct(fs);
3059 * Unshare file descriptor table if it is being shared
3061 int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3062 struct files_struct **new_fdp)
3064 struct files_struct *fd = current->files;
3067 if ((unshare_flags & CLONE_FILES) &&
3068 (fd && atomic_read(&fd->count) > 1)) {
3069 *new_fdp = dup_fd(fd, max_fds, &error);
3078 * unshare allows a process to 'unshare' part of the process
3079 * context which was originally shared using clone. copy_*
3080 * functions used by kernel_clone() cannot be used here directly
3081 * because they modify an inactive task_struct that is being
3082 * constructed. Here we are modifying the current, active,
3085 int ksys_unshare(unsigned long unshare_flags)
3087 struct fs_struct *fs, *new_fs = NULL;
3088 struct files_struct *new_fd = NULL;
3089 struct cred *new_cred = NULL;
3090 struct nsproxy *new_nsproxy = NULL;
3095 * If unsharing a user namespace must also unshare the thread group
3096 * and unshare the filesystem root and working directories.
3098 if (unshare_flags & CLONE_NEWUSER)
3099 unshare_flags |= CLONE_THREAD | CLONE_FS;
3101 * If unsharing vm, must also unshare signal handlers.
3103 if (unshare_flags & CLONE_VM)
3104 unshare_flags |= CLONE_SIGHAND;
3106 * If unsharing a signal handlers, must also unshare the signal queues.
3108 if (unshare_flags & CLONE_SIGHAND)
3109 unshare_flags |= CLONE_THREAD;
3111 * If unsharing namespace, must also unshare filesystem information.
3113 if (unshare_flags & CLONE_NEWNS)
3114 unshare_flags |= CLONE_FS;
3116 err = check_unshare_flags(unshare_flags);
3118 goto bad_unshare_out;
3120 * CLONE_NEWIPC must also detach from the undolist: after switching
3121 * to a new ipc namespace, the semaphore arrays from the old
3122 * namespace are unreachable.
3124 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3126 err = unshare_fs(unshare_flags, &new_fs);
3128 goto bad_unshare_out;
3129 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3131 goto bad_unshare_cleanup_fs;
3132 err = unshare_userns(unshare_flags, &new_cred);
3134 goto bad_unshare_cleanup_fd;
3135 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3138 goto bad_unshare_cleanup_cred;
3141 err = set_cred_ucounts(new_cred);
3143 goto bad_unshare_cleanup_cred;
3146 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3149 * CLONE_SYSVSEM is equivalent to sys_exit().
3153 if (unshare_flags & CLONE_NEWIPC) {
3154 /* Orphan segments in old ns (see sem above). */
3156 shm_init_task(current);
3160 switch_task_namespaces(current, new_nsproxy);
3166 spin_lock(&fs->lock);
3167 current->fs = new_fs;
3172 spin_unlock(&fs->lock);
3176 swap(current->files, new_fd);
3178 task_unlock(current);
3181 /* Install the new user namespace */
3182 commit_creds(new_cred);
3187 perf_event_namespaces(current);
3189 bad_unshare_cleanup_cred:
3192 bad_unshare_cleanup_fd:
3194 put_files_struct(new_fd);
3196 bad_unshare_cleanup_fs:
3198 free_fs_struct(new_fs);
3204 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3206 return ksys_unshare(unshare_flags);
3210 * Helper to unshare the files of the current task.
3211 * We don't want to expose copy_files internals to
3212 * the exec layer of the kernel.
3215 int unshare_files(void)
3217 struct task_struct *task = current;
3218 struct files_struct *old, *copy = NULL;
3221 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3229 put_files_struct(old);
3233 int sysctl_max_threads(struct ctl_table *table, int write,
3234 void *buffer, size_t *lenp, loff_t *ppos)
3238 int threads = max_threads;
3240 int max = MAX_THREADS;
3247 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3251 max_threads = threads;