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/vmacache.h>
46 #include <linux/nsproxy.h>
47 #include <linux/capability.h>
48 #include <linux/cpu.h>
49 #include <linux/cgroup.h>
50 #include <linux/security.h>
51 #include <linux/hugetlb.h>
52 #include <linux/seccomp.h>
53 #include <linux/swap.h>
54 #include <linux/syscalls.h>
55 #include <linux/jiffies.h>
56 #include <linux/futex.h>
57 #include <linux/compat.h>
58 #include <linux/kthread.h>
59 #include <linux/task_io_accounting_ops.h>
60 #include <linux/rcupdate.h>
61 #include <linux/ptrace.h>
62 #include <linux/mount.h>
63 #include <linux/audit.h>
64 #include <linux/memcontrol.h>
65 #include <linux/ftrace.h>
66 #include <linux/proc_fs.h>
67 #include <linux/profile.h>
68 #include <linux/rmap.h>
69 #include <linux/ksm.h>
70 #include <linux/acct.h>
71 #include <linux/userfaultfd_k.h>
72 #include <linux/tsacct_kern.h>
73 #include <linux/cn_proc.h>
74 #include <linux/freezer.h>
75 #include <linux/delayacct.h>
76 #include <linux/taskstats_kern.h>
77 #include <linux/random.h>
78 #include <linux/tty.h>
79 #include <linux/blkdev.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>
101 #include <asm/pgalloc.h>
102 #include <linux/uaccess.h>
103 #include <asm/mmu_context.h>
104 #include <asm/cacheflush.h>
105 #include <asm/tlbflush.h>
107 #include <trace/events/sched.h>
109 #define CREATE_TRACE_POINTS
110 #include <trace/events/task.h>
113 * Minimum number of threads to boot the kernel
115 #define MIN_THREADS 20
118 * Maximum number of threads
120 #define MAX_THREADS FUTEX_TID_MASK
123 * Protected counters by write_lock_irq(&tasklist_lock)
125 unsigned long total_forks; /* Handle normal Linux uptimes. */
126 int nr_threads; /* The idle threads do not count.. */
128 static int max_threads; /* tunable limit on nr_threads */
130 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
132 static const char * const resident_page_types[] = {
133 NAMED_ARRAY_INDEX(MM_FILEPAGES),
134 NAMED_ARRAY_INDEX(MM_ANONPAGES),
135 NAMED_ARRAY_INDEX(MM_SWAPENTS),
136 NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
139 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
141 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
143 #ifdef CONFIG_PROVE_RCU
144 int lockdep_tasklist_lock_is_held(void)
146 return lockdep_is_held(&tasklist_lock);
148 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
149 #endif /* #ifdef CONFIG_PROVE_RCU */
151 int nr_processes(void)
156 for_each_possible_cpu(cpu)
157 total += per_cpu(process_counts, cpu);
162 void __weak arch_release_task_struct(struct task_struct *tsk)
166 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
167 static struct kmem_cache *task_struct_cachep;
169 static inline struct task_struct *alloc_task_struct_node(int node)
171 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
174 static inline void free_task_struct(struct task_struct *tsk)
176 kmem_cache_free(task_struct_cachep, tsk);
180 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
183 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
184 * kmemcache based allocator.
186 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
188 #ifdef CONFIG_VMAP_STACK
190 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
191 * flush. Try to minimize the number of calls by caching stacks.
193 #define NR_CACHED_STACKS 2
194 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
196 static int free_vm_stack_cache(unsigned int cpu)
198 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
201 for (i = 0; i < NR_CACHED_STACKS; i++) {
202 struct vm_struct *vm_stack = cached_vm_stacks[i];
207 vfree(vm_stack->addr);
208 cached_vm_stacks[i] = NULL;
215 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
217 #ifdef CONFIG_VMAP_STACK
221 for (i = 0; i < NR_CACHED_STACKS; i++) {
224 s = this_cpu_xchg(cached_stacks[i], NULL);
229 /* Mark stack accessible for KASAN. */
230 kasan_unpoison_range(s->addr, THREAD_SIZE);
232 /* Clear stale pointers from reused stack. */
233 memset(s->addr, 0, THREAD_SIZE);
235 tsk->stack_vm_area = s;
236 tsk->stack = s->addr;
241 * Allocated stacks are cached and later reused by new threads,
242 * so memcg accounting is performed manually on assigning/releasing
243 * stacks to tasks. Drop __GFP_ACCOUNT.
245 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
246 VMALLOC_START, VMALLOC_END,
247 THREADINFO_GFP & ~__GFP_ACCOUNT,
249 0, node, __builtin_return_address(0));
252 * We can't call find_vm_area() in interrupt context, and
253 * free_thread_stack() can be called in interrupt context,
254 * so cache the vm_struct.
257 tsk->stack_vm_area = find_vm_area(stack);
262 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
266 tsk->stack = kasan_reset_tag(page_address(page));
273 static inline void free_thread_stack(struct task_struct *tsk)
275 #ifdef CONFIG_VMAP_STACK
276 struct vm_struct *vm = task_stack_vm_area(tsk);
281 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
282 memcg_kmem_uncharge_page(vm->pages[i], 0);
284 for (i = 0; i < NR_CACHED_STACKS; i++) {
285 if (this_cpu_cmpxchg(cached_stacks[i],
286 NULL, tsk->stack_vm_area) != NULL)
292 vfree_atomic(tsk->stack);
297 __free_pages(virt_to_page(tsk->stack), THREAD_SIZE_ORDER);
300 static struct kmem_cache *thread_stack_cache;
302 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk,
305 unsigned long *stack;
306 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
307 stack = kasan_reset_tag(stack);
312 static void free_thread_stack(struct task_struct *tsk)
314 kmem_cache_free(thread_stack_cache, tsk->stack);
317 void thread_stack_cache_init(void)
319 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
320 THREAD_SIZE, THREAD_SIZE, 0, 0,
322 BUG_ON(thread_stack_cache == NULL);
327 /* SLAB cache for signal_struct structures (tsk->signal) */
328 static struct kmem_cache *signal_cachep;
330 /* SLAB cache for sighand_struct structures (tsk->sighand) */
331 struct kmem_cache *sighand_cachep;
333 /* SLAB cache for files_struct structures (tsk->files) */
334 struct kmem_cache *files_cachep;
336 /* SLAB cache for fs_struct structures (tsk->fs) */
337 struct kmem_cache *fs_cachep;
339 /* SLAB cache for vm_area_struct structures */
340 static struct kmem_cache *vm_area_cachep;
342 /* SLAB cache for mm_struct structures (tsk->mm) */
343 static struct kmem_cache *mm_cachep;
345 struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
347 struct vm_area_struct *vma;
349 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
355 struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
357 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
360 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
361 ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
363 * orig->shared.rb may be modified concurrently, but the clone
364 * will be reinitialized.
366 *new = data_race(*orig);
367 INIT_LIST_HEAD(&new->anon_vma_chain);
368 new->vm_next = new->vm_prev = NULL;
373 void vm_area_free(struct vm_area_struct *vma)
375 kmem_cache_free(vm_area_cachep, vma);
378 static void account_kernel_stack(struct task_struct *tsk, int account)
380 void *stack = task_stack_page(tsk);
381 struct vm_struct *vm = task_stack_vm_area(tsk);
386 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
387 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
388 account * (PAGE_SIZE / 1024));
390 /* All stack pages are in the same node. */
391 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
392 account * (THREAD_SIZE / 1024));
396 static int memcg_charge_kernel_stack(struct task_struct *tsk)
398 #ifdef CONFIG_VMAP_STACK
399 struct vm_struct *vm = task_stack_vm_area(tsk);
402 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK) && PAGE_SIZE % 1024 != 0);
407 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
409 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
411 * If memcg_kmem_charge_page() fails, page's
412 * memory cgroup pointer is NULL, and
413 * memcg_kmem_uncharge_page() in free_thread_stack()
414 * will ignore this page.
416 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL,
426 static void release_task_stack(struct task_struct *tsk)
428 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
429 return; /* Better to leak the stack than to free prematurely */
431 account_kernel_stack(tsk, -1);
432 free_thread_stack(tsk);
434 #ifdef CONFIG_VMAP_STACK
435 tsk->stack_vm_area = NULL;
439 #ifdef CONFIG_THREAD_INFO_IN_TASK
440 void put_task_stack(struct task_struct *tsk)
442 if (refcount_dec_and_test(&tsk->stack_refcount))
443 release_task_stack(tsk);
447 void free_task(struct task_struct *tsk)
449 release_user_cpus_ptr(tsk);
452 #ifndef CONFIG_THREAD_INFO_IN_TASK
454 * The task is finally done with both the stack and thread_info,
457 release_task_stack(tsk);
460 * If the task had a separate stack allocation, it should be gone
463 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
465 rt_mutex_debug_task_free(tsk);
466 ftrace_graph_exit_task(tsk);
467 arch_release_task_struct(tsk);
468 if (tsk->flags & PF_KTHREAD)
469 free_kthread_struct(tsk);
470 free_task_struct(tsk);
472 EXPORT_SYMBOL(free_task);
474 static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
476 struct file *exe_file;
478 exe_file = get_mm_exe_file(oldmm);
479 RCU_INIT_POINTER(mm->exe_file, exe_file);
481 * We depend on the oldmm having properly denied write access to the
484 if (exe_file && deny_write_access(exe_file))
485 pr_warn_once("deny_write_access() failed in %s\n", __func__);
489 static __latent_entropy int dup_mmap(struct mm_struct *mm,
490 struct mm_struct *oldmm)
492 struct vm_area_struct *mpnt, *tmp, *prev, **pprev;
493 struct rb_node **rb_link, *rb_parent;
495 unsigned long charge;
498 uprobe_start_dup_mmap();
499 if (mmap_write_lock_killable(oldmm)) {
501 goto fail_uprobe_end;
503 flush_cache_dup_mm(oldmm);
504 uprobe_dup_mmap(oldmm, mm);
506 * Not linked in yet - no deadlock potential:
508 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
510 /* No ordering required: file already has been exposed. */
511 dup_mm_exe_file(mm, oldmm);
513 mm->total_vm = oldmm->total_vm;
514 mm->data_vm = oldmm->data_vm;
515 mm->exec_vm = oldmm->exec_vm;
516 mm->stack_vm = oldmm->stack_vm;
518 rb_link = &mm->mm_rb.rb_node;
521 retval = ksm_fork(mm, oldmm);
524 retval = khugepaged_fork(mm, oldmm);
529 for (mpnt = oldmm->mmap; mpnt; mpnt = mpnt->vm_next) {
532 if (mpnt->vm_flags & VM_DONTCOPY) {
533 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
538 * Don't duplicate many vmas if we've been oom-killed (for
541 if (fatal_signal_pending(current)) {
545 if (mpnt->vm_flags & VM_ACCOUNT) {
546 unsigned long len = vma_pages(mpnt);
548 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
552 tmp = vm_area_dup(mpnt);
555 retval = vma_dup_policy(mpnt, tmp);
557 goto fail_nomem_policy;
559 retval = dup_userfaultfd(tmp, &uf);
561 goto fail_nomem_anon_vma_fork;
562 if (tmp->vm_flags & VM_WIPEONFORK) {
564 * VM_WIPEONFORK gets a clean slate in the child.
565 * Don't prepare anon_vma until fault since we don't
566 * copy page for current vma.
568 tmp->anon_vma = NULL;
569 } else if (anon_vma_fork(tmp, mpnt))
570 goto fail_nomem_anon_vma_fork;
571 tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
574 struct address_space *mapping = file->f_mapping;
577 i_mmap_lock_write(mapping);
578 if (tmp->vm_flags & VM_SHARED)
579 mapping_allow_writable(mapping);
580 flush_dcache_mmap_lock(mapping);
581 /* insert tmp into the share list, just after mpnt */
582 vma_interval_tree_insert_after(tmp, mpnt,
584 flush_dcache_mmap_unlock(mapping);
585 i_mmap_unlock_write(mapping);
589 * Clear hugetlb-related page reserves for children. This only
590 * affects MAP_PRIVATE mappings. Faults generated by the child
591 * are not guaranteed to succeed, even if read-only
593 if (is_vm_hugetlb_page(tmp))
594 reset_vma_resv_huge_pages(tmp);
597 * Link in the new vma and copy the page table entries.
600 pprev = &tmp->vm_next;
604 __vma_link_rb(mm, tmp, rb_link, rb_parent);
605 rb_link = &tmp->vm_rb.rb_right;
606 rb_parent = &tmp->vm_rb;
609 if (!(tmp->vm_flags & VM_WIPEONFORK))
610 retval = copy_page_range(tmp, mpnt);
612 if (tmp->vm_ops && tmp->vm_ops->open)
613 tmp->vm_ops->open(tmp);
618 /* a new mm has just been created */
619 retval = arch_dup_mmap(oldmm, mm);
621 mmap_write_unlock(mm);
623 mmap_write_unlock(oldmm);
624 dup_userfaultfd_complete(&uf);
626 uprobe_end_dup_mmap();
628 fail_nomem_anon_vma_fork:
629 mpol_put(vma_policy(tmp));
634 vm_unacct_memory(charge);
638 static inline int mm_alloc_pgd(struct mm_struct *mm)
640 mm->pgd = pgd_alloc(mm);
641 if (unlikely(!mm->pgd))
646 static inline void mm_free_pgd(struct mm_struct *mm)
648 pgd_free(mm, mm->pgd);
651 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
653 mmap_write_lock(oldmm);
654 dup_mm_exe_file(mm, oldmm);
655 mmap_write_unlock(oldmm);
658 #define mm_alloc_pgd(mm) (0)
659 #define mm_free_pgd(mm)
660 #endif /* CONFIG_MMU */
662 static void check_mm(struct mm_struct *mm)
666 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
667 "Please make sure 'struct resident_page_types[]' is updated as well");
669 for (i = 0; i < NR_MM_COUNTERS; i++) {
670 long x = atomic_long_read(&mm->rss_stat.count[i]);
673 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
674 mm, resident_page_types[i], x);
677 if (mm_pgtables_bytes(mm))
678 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
679 mm_pgtables_bytes(mm));
681 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
682 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
686 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
687 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
690 * Called when the last reference to the mm
691 * is dropped: either by a lazy thread or by
692 * mmput. Free the page directory and the mm.
694 void __mmdrop(struct mm_struct *mm)
696 BUG_ON(mm == &init_mm);
697 WARN_ON_ONCE(mm == current->mm);
698 WARN_ON_ONCE(mm == current->active_mm);
701 mmu_notifier_subscriptions_destroy(mm);
703 put_user_ns(mm->user_ns);
706 EXPORT_SYMBOL_GPL(__mmdrop);
708 static void mmdrop_async_fn(struct work_struct *work)
710 struct mm_struct *mm;
712 mm = container_of(work, struct mm_struct, async_put_work);
716 static void mmdrop_async(struct mm_struct *mm)
718 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
719 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
720 schedule_work(&mm->async_put_work);
724 static inline void free_signal_struct(struct signal_struct *sig)
726 taskstats_tgid_free(sig);
727 sched_autogroup_exit(sig);
729 * __mmdrop is not safe to call from softirq context on x86 due to
730 * pgd_dtor so postpone it to the async context
733 mmdrop_async(sig->oom_mm);
734 kmem_cache_free(signal_cachep, sig);
737 static inline void put_signal_struct(struct signal_struct *sig)
739 if (refcount_dec_and_test(&sig->sigcnt))
740 free_signal_struct(sig);
743 void __put_task_struct(struct task_struct *tsk)
745 WARN_ON(!tsk->exit_state);
746 WARN_ON(refcount_read(&tsk->usage));
747 WARN_ON(tsk == current);
751 task_numa_free(tsk, true);
752 security_task_free(tsk);
753 bpf_task_storage_free(tsk);
755 delayacct_tsk_free(tsk);
756 put_signal_struct(tsk->signal);
757 sched_core_free(tsk);
759 if (!profile_handoff_task(tsk))
762 EXPORT_SYMBOL_GPL(__put_task_struct);
764 void __init __weak arch_task_cache_init(void) { }
769 static void set_max_threads(unsigned int max_threads_suggested)
772 unsigned long nr_pages = totalram_pages();
775 * The number of threads shall be limited such that the thread
776 * structures may only consume a small part of the available memory.
778 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
779 threads = MAX_THREADS;
781 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
782 (u64) THREAD_SIZE * 8UL);
784 if (threads > max_threads_suggested)
785 threads = max_threads_suggested;
787 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
790 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
791 /* Initialized by the architecture: */
792 int arch_task_struct_size __read_mostly;
795 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
796 static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
798 /* Fetch thread_struct whitelist for the architecture. */
799 arch_thread_struct_whitelist(offset, size);
802 * Handle zero-sized whitelist or empty thread_struct, otherwise
803 * adjust offset to position of thread_struct in task_struct.
805 if (unlikely(*size == 0))
808 *offset += offsetof(struct task_struct, thread);
810 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
812 void __init fork_init(void)
815 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
816 #ifndef ARCH_MIN_TASKALIGN
817 #define ARCH_MIN_TASKALIGN 0
819 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
820 unsigned long useroffset, usersize;
822 /* create a slab on which task_structs can be allocated */
823 task_struct_whitelist(&useroffset, &usersize);
824 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
825 arch_task_struct_size, align,
826 SLAB_PANIC|SLAB_ACCOUNT,
827 useroffset, usersize, NULL);
830 /* do the arch specific task caches init */
831 arch_task_cache_init();
833 set_max_threads(MAX_THREADS);
835 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
836 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
837 init_task.signal->rlim[RLIMIT_SIGPENDING] =
838 init_task.signal->rlim[RLIMIT_NPROC];
840 for (i = 0; i < MAX_PER_NAMESPACE_UCOUNTS; i++)
841 init_user_ns.ucount_max[i] = max_threads/2;
843 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
844 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
845 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
846 set_rlimit_ucount_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
848 #ifdef CONFIG_VMAP_STACK
849 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
850 NULL, free_vm_stack_cache);
855 lockdep_init_task(&init_task);
859 int __weak arch_dup_task_struct(struct task_struct *dst,
860 struct task_struct *src)
866 void set_task_stack_end_magic(struct task_struct *tsk)
868 unsigned long *stackend;
870 stackend = end_of_stack(tsk);
871 *stackend = STACK_END_MAGIC; /* for overflow detection */
874 static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
876 struct task_struct *tsk;
877 unsigned long *stack;
878 struct vm_struct *stack_vm_area __maybe_unused;
881 if (node == NUMA_NO_NODE)
882 node = tsk_fork_get_node(orig);
883 tsk = alloc_task_struct_node(node);
887 stack = alloc_thread_stack_node(tsk, node);
891 if (memcg_charge_kernel_stack(tsk))
894 stack_vm_area = task_stack_vm_area(tsk);
896 err = arch_dup_task_struct(tsk, orig);
899 * arch_dup_task_struct() clobbers the stack-related fields. Make
900 * sure they're properly initialized before using any stack-related
904 #ifdef CONFIG_VMAP_STACK
905 tsk->stack_vm_area = stack_vm_area;
907 #ifdef CONFIG_THREAD_INFO_IN_TASK
908 refcount_set(&tsk->stack_refcount, 1);
914 err = scs_prepare(tsk, node);
918 #ifdef CONFIG_SECCOMP
920 * We must handle setting up seccomp filters once we're under
921 * the sighand lock in case orig has changed between now and
922 * then. Until then, filter must be NULL to avoid messing up
923 * the usage counts on the error path calling free_task.
925 tsk->seccomp.filter = NULL;
928 setup_thread_stack(tsk, orig);
929 clear_user_return_notifier(tsk);
930 clear_tsk_need_resched(tsk);
931 set_task_stack_end_magic(tsk);
932 clear_syscall_work_syscall_user_dispatch(tsk);
934 #ifdef CONFIG_STACKPROTECTOR
935 tsk->stack_canary = get_random_canary();
937 if (orig->cpus_ptr == &orig->cpus_mask)
938 tsk->cpus_ptr = &tsk->cpus_mask;
939 dup_user_cpus_ptr(tsk, orig, node);
942 * One for the user space visible state that goes away when reaped.
943 * One for the scheduler.
945 refcount_set(&tsk->rcu_users, 2);
946 /* One for the rcu users */
947 refcount_set(&tsk->usage, 1);
948 #ifdef CONFIG_BLK_DEV_IO_TRACE
951 tsk->splice_pipe = NULL;
952 tsk->task_frag.page = NULL;
953 tsk->wake_q.next = NULL;
954 tsk->pf_io_worker = NULL;
956 account_kernel_stack(tsk, 1);
959 kmap_local_fork(tsk);
961 #ifdef CONFIG_FAULT_INJECTION
965 #ifdef CONFIG_BLK_CGROUP
966 tsk->throttle_queue = NULL;
967 tsk->use_memdelay = 0;
971 tsk->active_memcg = NULL;
976 free_thread_stack(tsk);
978 free_task_struct(tsk);
982 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
984 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
986 static int __init coredump_filter_setup(char *s)
988 default_dump_filter =
989 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
990 MMF_DUMP_FILTER_MASK;
994 __setup("coredump_filter=", coredump_filter_setup);
996 #include <linux/init_task.h>
998 static void mm_init_aio(struct mm_struct *mm)
1001 spin_lock_init(&mm->ioctx_lock);
1002 mm->ioctx_table = NULL;
1006 static __always_inline void mm_clear_owner(struct mm_struct *mm,
1007 struct task_struct *p)
1011 WRITE_ONCE(mm->owner, NULL);
1015 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1022 static void mm_init_pasid(struct mm_struct *mm)
1024 #ifdef CONFIG_IOMMU_SUPPORT
1025 mm->pasid = INIT_PASID;
1029 static void mm_init_uprobes_state(struct mm_struct *mm)
1031 #ifdef CONFIG_UPROBES
1032 mm->uprobes_state.xol_area = NULL;
1036 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1037 struct user_namespace *user_ns)
1040 mm->mm_rb = RB_ROOT;
1041 mm->vmacache_seqnum = 0;
1042 atomic_set(&mm->mm_users, 1);
1043 atomic_set(&mm->mm_count, 1);
1044 seqcount_init(&mm->write_protect_seq);
1046 INIT_LIST_HEAD(&mm->mmlist);
1047 mm->core_state = NULL;
1048 mm_pgtables_bytes_init(mm);
1051 atomic64_set(&mm->pinned_vm, 0);
1052 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1053 spin_lock_init(&mm->page_table_lock);
1054 spin_lock_init(&mm->arg_lock);
1055 mm_init_cpumask(mm);
1057 mm_init_owner(mm, p);
1059 RCU_INIT_POINTER(mm->exe_file, NULL);
1060 mmu_notifier_subscriptions_init(mm);
1061 init_tlb_flush_pending(mm);
1062 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1063 mm->pmd_huge_pte = NULL;
1065 mm_init_uprobes_state(mm);
1066 hugetlb_count_init(mm);
1069 mm->flags = current->mm->flags & MMF_INIT_MASK;
1070 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1072 mm->flags = default_dump_filter;
1076 if (mm_alloc_pgd(mm))
1079 if (init_new_context(p, mm))
1080 goto fail_nocontext;
1082 mm->user_ns = get_user_ns(user_ns);
1093 * Allocate and initialize an mm_struct.
1095 struct mm_struct *mm_alloc(void)
1097 struct mm_struct *mm;
1103 memset(mm, 0, sizeof(*mm));
1104 return mm_init(mm, current, current_user_ns());
1107 static inline void __mmput(struct mm_struct *mm)
1109 VM_BUG_ON(atomic_read(&mm->mm_users));
1111 uprobe_clear_state(mm);
1114 khugepaged_exit(mm); /* must run before exit_mmap */
1116 mm_put_huge_zero_page(mm);
1117 set_mm_exe_file(mm, NULL);
1118 if (!list_empty(&mm->mmlist)) {
1119 spin_lock(&mmlist_lock);
1120 list_del(&mm->mmlist);
1121 spin_unlock(&mmlist_lock);
1124 module_put(mm->binfmt->module);
1129 * Decrement the use count and release all resources for an mm.
1131 void mmput(struct mm_struct *mm)
1135 if (atomic_dec_and_test(&mm->mm_users))
1138 EXPORT_SYMBOL_GPL(mmput);
1141 static void mmput_async_fn(struct work_struct *work)
1143 struct mm_struct *mm = container_of(work, struct mm_struct,
1149 void mmput_async(struct mm_struct *mm)
1151 if (atomic_dec_and_test(&mm->mm_users)) {
1152 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1153 schedule_work(&mm->async_put_work);
1156 EXPORT_SYMBOL_GPL(mmput_async);
1160 * set_mm_exe_file - change a reference to the mm's executable file
1162 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1164 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1165 * invocations: in mmput() nobody alive left, in execve task is single
1168 * Can only fail if new_exe_file != NULL.
1170 int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1172 struct file *old_exe_file;
1175 * It is safe to dereference the exe_file without RCU as
1176 * this function is only called if nobody else can access
1177 * this mm -- see comment above for justification.
1179 old_exe_file = rcu_dereference_raw(mm->exe_file);
1183 * We expect the caller (i.e., sys_execve) to already denied
1184 * write access, so this is unlikely to fail.
1186 if (unlikely(deny_write_access(new_exe_file)))
1188 get_file(new_exe_file);
1190 rcu_assign_pointer(mm->exe_file, new_exe_file);
1192 allow_write_access(old_exe_file);
1199 * replace_mm_exe_file - replace a reference to the mm's executable file
1201 * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
1202 * dealing with concurrent invocation and without grabbing the mmap lock in
1205 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1207 int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1209 struct vm_area_struct *vma;
1210 struct file *old_exe_file;
1213 /* Forbid mm->exe_file change if old file still mapped. */
1214 old_exe_file = get_mm_exe_file(mm);
1217 for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) {
1220 if (path_equal(&vma->vm_file->f_path,
1221 &old_exe_file->f_path))
1224 mmap_read_unlock(mm);
1230 /* set the new file, lockless */
1231 ret = deny_write_access(new_exe_file);
1234 get_file(new_exe_file);
1236 old_exe_file = xchg(&mm->exe_file, new_exe_file);
1239 * Don't race with dup_mmap() getting the file and disallowing
1240 * write access while someone might open the file writable.
1243 allow_write_access(old_exe_file);
1245 mmap_read_unlock(mm);
1251 * get_mm_exe_file - acquire a reference to the mm's executable file
1253 * Returns %NULL if mm has no associated executable file.
1254 * User must release file via fput().
1256 struct file *get_mm_exe_file(struct mm_struct *mm)
1258 struct file *exe_file;
1261 exe_file = rcu_dereference(mm->exe_file);
1262 if (exe_file && !get_file_rcu(exe_file))
1269 * get_task_exe_file - acquire a reference to the task's executable file
1271 * Returns %NULL if task's mm (if any) has no associated executable file or
1272 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1273 * User must release file via fput().
1275 struct file *get_task_exe_file(struct task_struct *task)
1277 struct file *exe_file = NULL;
1278 struct mm_struct *mm;
1283 if (!(task->flags & PF_KTHREAD))
1284 exe_file = get_mm_exe_file(mm);
1291 * get_task_mm - acquire a reference to the task's mm
1293 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1294 * this kernel workthread has transiently adopted a user mm with use_mm,
1295 * to do its AIO) is not set and if so returns a reference to it, after
1296 * bumping up the use count. User must release the mm via mmput()
1297 * after use. Typically used by /proc and ptrace.
1299 struct mm_struct *get_task_mm(struct task_struct *task)
1301 struct mm_struct *mm;
1306 if (task->flags & PF_KTHREAD)
1314 EXPORT_SYMBOL_GPL(get_task_mm);
1316 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1318 struct mm_struct *mm;
1321 err = down_read_killable(&task->signal->exec_update_lock);
1323 return ERR_PTR(err);
1325 mm = get_task_mm(task);
1326 if (mm && mm != current->mm &&
1327 !ptrace_may_access(task, mode)) {
1329 mm = ERR_PTR(-EACCES);
1331 up_read(&task->signal->exec_update_lock);
1336 static void complete_vfork_done(struct task_struct *tsk)
1338 struct completion *vfork;
1341 vfork = tsk->vfork_done;
1342 if (likely(vfork)) {
1343 tsk->vfork_done = NULL;
1349 static int wait_for_vfork_done(struct task_struct *child,
1350 struct completion *vfork)
1354 freezer_do_not_count();
1355 cgroup_enter_frozen();
1356 killed = wait_for_completion_killable(vfork);
1357 cgroup_leave_frozen(false);
1362 child->vfork_done = NULL;
1366 put_task_struct(child);
1370 /* Please note the differences between mmput and mm_release.
1371 * mmput is called whenever we stop holding onto a mm_struct,
1372 * error success whatever.
1374 * mm_release is called after a mm_struct has been removed
1375 * from the current process.
1377 * This difference is important for error handling, when we
1378 * only half set up a mm_struct for a new process and need to restore
1379 * the old one. Because we mmput the new mm_struct before
1380 * restoring the old one. . .
1381 * Eric Biederman 10 January 1998
1383 static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1385 uprobe_free_utask(tsk);
1387 /* Get rid of any cached register state */
1388 deactivate_mm(tsk, mm);
1391 * Signal userspace if we're not exiting with a core dump
1392 * because we want to leave the value intact for debugging
1395 if (tsk->clear_child_tid) {
1396 if (!(tsk->signal->flags & SIGNAL_GROUP_COREDUMP) &&
1397 atomic_read(&mm->mm_users) > 1) {
1399 * We don't check the error code - if userspace has
1400 * not set up a proper pointer then tough luck.
1402 put_user(0, tsk->clear_child_tid);
1403 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1404 1, NULL, NULL, 0, 0);
1406 tsk->clear_child_tid = NULL;
1410 * All done, finally we can wake up parent and return this mm to him.
1411 * Also kthread_stop() uses this completion for synchronization.
1413 if (tsk->vfork_done)
1414 complete_vfork_done(tsk);
1417 void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1419 futex_exit_release(tsk);
1420 mm_release(tsk, mm);
1423 void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1425 futex_exec_release(tsk);
1426 mm_release(tsk, mm);
1430 * dup_mm() - duplicates an existing mm structure
1431 * @tsk: the task_struct with which the new mm will be associated.
1432 * @oldmm: the mm to duplicate.
1434 * Allocates a new mm structure and duplicates the provided @oldmm structure
1437 * Return: the duplicated mm or NULL on failure.
1439 static struct mm_struct *dup_mm(struct task_struct *tsk,
1440 struct mm_struct *oldmm)
1442 struct mm_struct *mm;
1449 memcpy(mm, oldmm, sizeof(*mm));
1451 if (!mm_init(mm, tsk, mm->user_ns))
1454 err = dup_mmap(mm, oldmm);
1458 mm->hiwater_rss = get_mm_rss(mm);
1459 mm->hiwater_vm = mm->total_vm;
1461 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1467 /* don't put binfmt in mmput, we haven't got module yet */
1469 mm_init_owner(mm, NULL);
1476 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1478 struct mm_struct *mm, *oldmm;
1480 tsk->min_flt = tsk->maj_flt = 0;
1481 tsk->nvcsw = tsk->nivcsw = 0;
1482 #ifdef CONFIG_DETECT_HUNG_TASK
1483 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1484 tsk->last_switch_time = 0;
1488 tsk->active_mm = NULL;
1491 * Are we cloning a kernel thread?
1493 * We need to steal a active VM for that..
1495 oldmm = current->mm;
1499 /* initialize the new vmacache entries */
1500 vmacache_flush(tsk);
1502 if (clone_flags & CLONE_VM) {
1506 mm = dup_mm(tsk, current->mm);
1512 tsk->active_mm = mm;
1516 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1518 struct fs_struct *fs = current->fs;
1519 if (clone_flags & CLONE_FS) {
1520 /* tsk->fs is already what we want */
1521 spin_lock(&fs->lock);
1523 spin_unlock(&fs->lock);
1527 spin_unlock(&fs->lock);
1530 tsk->fs = copy_fs_struct(fs);
1536 static int copy_files(unsigned long clone_flags, struct task_struct *tsk)
1538 struct files_struct *oldf, *newf;
1542 * A background process may not have any files ...
1544 oldf = current->files;
1548 if (clone_flags & CLONE_FILES) {
1549 atomic_inc(&oldf->count);
1553 newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1563 static int copy_io(unsigned long clone_flags, struct task_struct *tsk)
1566 struct io_context *ioc = current->io_context;
1567 struct io_context *new_ioc;
1572 * Share io context with parent, if CLONE_IO is set
1574 if (clone_flags & CLONE_IO) {
1576 tsk->io_context = ioc;
1577 } else if (ioprio_valid(ioc->ioprio)) {
1578 new_ioc = get_task_io_context(tsk, GFP_KERNEL, NUMA_NO_NODE);
1579 if (unlikely(!new_ioc))
1582 new_ioc->ioprio = ioc->ioprio;
1583 put_io_context(new_ioc);
1589 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1591 struct sighand_struct *sig;
1593 if (clone_flags & CLONE_SIGHAND) {
1594 refcount_inc(¤t->sighand->count);
1597 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1598 RCU_INIT_POINTER(tsk->sighand, sig);
1602 refcount_set(&sig->count, 1);
1603 spin_lock_irq(¤t->sighand->siglock);
1604 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1605 spin_unlock_irq(¤t->sighand->siglock);
1607 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1608 if (clone_flags & CLONE_CLEAR_SIGHAND)
1609 flush_signal_handlers(tsk, 0);
1614 void __cleanup_sighand(struct sighand_struct *sighand)
1616 if (refcount_dec_and_test(&sighand->count)) {
1617 signalfd_cleanup(sighand);
1619 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1620 * without an RCU grace period, see __lock_task_sighand().
1622 kmem_cache_free(sighand_cachep, sighand);
1627 * Initialize POSIX timer handling for a thread group.
1629 static void posix_cpu_timers_init_group(struct signal_struct *sig)
1631 struct posix_cputimers *pct = &sig->posix_cputimers;
1632 unsigned long cpu_limit;
1634 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1635 posix_cputimers_group_init(pct, cpu_limit);
1638 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1640 struct signal_struct *sig;
1642 if (clone_flags & CLONE_THREAD)
1645 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1650 sig->nr_threads = 1;
1651 atomic_set(&sig->live, 1);
1652 refcount_set(&sig->sigcnt, 1);
1654 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1655 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1656 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1658 init_waitqueue_head(&sig->wait_chldexit);
1659 sig->curr_target = tsk;
1660 init_sigpending(&sig->shared_pending);
1661 INIT_HLIST_HEAD(&sig->multiprocess);
1662 seqlock_init(&sig->stats_lock);
1663 prev_cputime_init(&sig->prev_cputime);
1665 #ifdef CONFIG_POSIX_TIMERS
1666 INIT_LIST_HEAD(&sig->posix_timers);
1667 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1668 sig->real_timer.function = it_real_fn;
1671 task_lock(current->group_leader);
1672 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1673 task_unlock(current->group_leader);
1675 posix_cpu_timers_init_group(sig);
1677 tty_audit_fork(sig);
1678 sched_autogroup_fork(sig);
1680 sig->oom_score_adj = current->signal->oom_score_adj;
1681 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1683 mutex_init(&sig->cred_guard_mutex);
1684 init_rwsem(&sig->exec_update_lock);
1689 static void copy_seccomp(struct task_struct *p)
1691 #ifdef CONFIG_SECCOMP
1693 * Must be called with sighand->lock held, which is common to
1694 * all threads in the group. Holding cred_guard_mutex is not
1695 * needed because this new task is not yet running and cannot
1698 assert_spin_locked(¤t->sighand->siglock);
1700 /* Ref-count the new filter user, and assign it. */
1701 get_seccomp_filter(current);
1702 p->seccomp = current->seccomp;
1705 * Explicitly enable no_new_privs here in case it got set
1706 * between the task_struct being duplicated and holding the
1707 * sighand lock. The seccomp state and nnp must be in sync.
1709 if (task_no_new_privs(current))
1710 task_set_no_new_privs(p);
1713 * If the parent gained a seccomp mode after copying thread
1714 * flags and between before we held the sighand lock, we have
1715 * to manually enable the seccomp thread flag here.
1717 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1718 set_task_syscall_work(p, SECCOMP);
1722 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1724 current->clear_child_tid = tidptr;
1726 return task_pid_vnr(current);
1729 static void rt_mutex_init_task(struct task_struct *p)
1731 raw_spin_lock_init(&p->pi_lock);
1732 #ifdef CONFIG_RT_MUTEXES
1733 p->pi_waiters = RB_ROOT_CACHED;
1734 p->pi_top_task = NULL;
1735 p->pi_blocked_on = NULL;
1739 static inline void init_task_pid_links(struct task_struct *task)
1743 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1744 INIT_HLIST_NODE(&task->pid_links[type]);
1748 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1750 if (type == PIDTYPE_PID)
1751 task->thread_pid = pid;
1753 task->signal->pids[type] = pid;
1756 static inline void rcu_copy_process(struct task_struct *p)
1758 #ifdef CONFIG_PREEMPT_RCU
1759 p->rcu_read_lock_nesting = 0;
1760 p->rcu_read_unlock_special.s = 0;
1761 p->rcu_blocked_node = NULL;
1762 INIT_LIST_HEAD(&p->rcu_node_entry);
1763 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1764 #ifdef CONFIG_TASKS_RCU
1765 p->rcu_tasks_holdout = false;
1766 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1767 p->rcu_tasks_idle_cpu = -1;
1768 #endif /* #ifdef CONFIG_TASKS_RCU */
1769 #ifdef CONFIG_TASKS_TRACE_RCU
1770 p->trc_reader_nesting = 0;
1771 p->trc_reader_special.s = 0;
1772 INIT_LIST_HEAD(&p->trc_holdout_list);
1773 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1776 struct pid *pidfd_pid(const struct file *file)
1778 if (file->f_op == &pidfd_fops)
1779 return file->private_data;
1781 return ERR_PTR(-EBADF);
1784 static int pidfd_release(struct inode *inode, struct file *file)
1786 struct pid *pid = file->private_data;
1788 file->private_data = NULL;
1793 #ifdef CONFIG_PROC_FS
1795 * pidfd_show_fdinfo - print information about a pidfd
1796 * @m: proc fdinfo file
1797 * @f: file referencing a pidfd
1800 * This function will print the pid that a given pidfd refers to in the
1801 * pid namespace of the procfs instance.
1802 * If the pid namespace of the process is not a descendant of the pid
1803 * namespace of the procfs instance 0 will be shown as its pid. This is
1804 * similar to calling getppid() on a process whose parent is outside of
1805 * its pid namespace.
1808 * If pid namespaces are supported then this function will also print
1809 * the pid of a given pidfd refers to for all descendant pid namespaces
1810 * starting from the current pid namespace of the instance, i.e. the
1811 * Pid field and the first entry in the NSpid field will be identical.
1812 * If the pid namespace of the process is not a descendant of the pid
1813 * namespace of the procfs instance 0 will be shown as its first NSpid
1814 * entry and no others will be shown.
1815 * Note that this differs from the Pid and NSpid fields in
1816 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1817 * the pid namespace of the procfs instance. The difference becomes
1818 * obvious when sending around a pidfd between pid namespaces from a
1819 * different branch of the tree, i.e. where no ancestral relation is
1820 * present between the pid namespaces:
1821 * - create two new pid namespaces ns1 and ns2 in the initial pid
1822 * namespace (also take care to create new mount namespaces in the
1823 * new pid namespace and mount procfs)
1824 * - create a process with a pidfd in ns1
1825 * - send pidfd from ns1 to ns2
1826 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1827 * have exactly one entry, which is 0
1829 static void pidfd_show_fdinfo(struct seq_file *m, struct file *f)
1831 struct pid *pid = f->private_data;
1832 struct pid_namespace *ns;
1835 if (likely(pid_has_task(pid, PIDTYPE_PID))) {
1836 ns = proc_pid_ns(file_inode(m->file)->i_sb);
1837 nr = pid_nr_ns(pid, ns);
1840 seq_put_decimal_ll(m, "Pid:\t", nr);
1842 #ifdef CONFIG_PID_NS
1843 seq_put_decimal_ll(m, "\nNSpid:\t", nr);
1847 /* If nr is non-zero it means that 'pid' is valid and that
1848 * ns, i.e. the pid namespace associated with the procfs
1849 * instance, is in the pid namespace hierarchy of pid.
1850 * Start at one below the already printed level.
1852 for (i = ns->level + 1; i <= pid->level; i++)
1853 seq_put_decimal_ll(m, "\t", pid->numbers[i].nr);
1861 * Poll support for process exit notification.
1863 static __poll_t pidfd_poll(struct file *file, struct poll_table_struct *pts)
1865 struct pid *pid = file->private_data;
1866 __poll_t poll_flags = 0;
1868 poll_wait(file, &pid->wait_pidfd, pts);
1871 * Inform pollers only when the whole thread group exits.
1872 * If the thread group leader exits before all other threads in the
1873 * group, then poll(2) should block, similar to the wait(2) family.
1875 if (thread_group_exited(pid))
1876 poll_flags = EPOLLIN | EPOLLRDNORM;
1881 const struct file_operations pidfd_fops = {
1882 .release = pidfd_release,
1884 #ifdef CONFIG_PROC_FS
1885 .show_fdinfo = pidfd_show_fdinfo,
1889 static void __delayed_free_task(struct rcu_head *rhp)
1891 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
1896 static __always_inline void delayed_free_task(struct task_struct *tsk)
1898 if (IS_ENABLED(CONFIG_MEMCG))
1899 call_rcu(&tsk->rcu, __delayed_free_task);
1904 static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
1906 /* Skip if kernel thread */
1910 /* Skip if spawning a thread or using vfork */
1911 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
1914 /* We need to synchronize with __set_oom_adj */
1915 mutex_lock(&oom_adj_mutex);
1916 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
1917 /* Update the values in case they were changed after copy_signal */
1918 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
1919 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
1920 mutex_unlock(&oom_adj_mutex);
1924 * This creates a new process as a copy of the old one,
1925 * but does not actually start it yet.
1927 * It copies the registers, and all the appropriate
1928 * parts of the process environment (as per the clone
1929 * flags). The actual kick-off is left to the caller.
1931 static __latent_entropy struct task_struct *copy_process(
1935 struct kernel_clone_args *args)
1937 int pidfd = -1, retval;
1938 struct task_struct *p;
1939 struct multiprocess_signals delayed;
1940 struct file *pidfile = NULL;
1941 u64 clone_flags = args->flags;
1942 struct nsproxy *nsp = current->nsproxy;
1945 * Don't allow sharing the root directory with processes in a different
1948 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
1949 return ERR_PTR(-EINVAL);
1951 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
1952 return ERR_PTR(-EINVAL);
1955 * Thread groups must share signals as well, and detached threads
1956 * can only be started up within the thread group.
1958 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
1959 return ERR_PTR(-EINVAL);
1962 * Shared signal handlers imply shared VM. By way of the above,
1963 * thread groups also imply shared VM. Blocking this case allows
1964 * for various simplifications in other code.
1966 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
1967 return ERR_PTR(-EINVAL);
1970 * Siblings of global init remain as zombies on exit since they are
1971 * not reaped by their parent (swapper). To solve this and to avoid
1972 * multi-rooted process trees, prevent global and container-inits
1973 * from creating siblings.
1975 if ((clone_flags & CLONE_PARENT) &&
1976 current->signal->flags & SIGNAL_UNKILLABLE)
1977 return ERR_PTR(-EINVAL);
1980 * If the new process will be in a different pid or user namespace
1981 * do not allow it to share a thread group with the forking task.
1983 if (clone_flags & CLONE_THREAD) {
1984 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
1985 (task_active_pid_ns(current) != nsp->pid_ns_for_children))
1986 return ERR_PTR(-EINVAL);
1990 * If the new process will be in a different time namespace
1991 * do not allow it to share VM or a thread group with the forking task.
1993 if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
1994 if (nsp->time_ns != nsp->time_ns_for_children)
1995 return ERR_PTR(-EINVAL);
1998 if (clone_flags & CLONE_PIDFD) {
2000 * - CLONE_DETACHED is blocked so that we can potentially
2001 * reuse it later for CLONE_PIDFD.
2002 * - CLONE_THREAD is blocked until someone really needs it.
2004 if (clone_flags & (CLONE_DETACHED | CLONE_THREAD))
2005 return ERR_PTR(-EINVAL);
2009 * Force any signals received before this point to be delivered
2010 * before the fork happens. Collect up signals sent to multiple
2011 * processes that happen during the fork and delay them so that
2012 * they appear to happen after the fork.
2014 sigemptyset(&delayed.signal);
2015 INIT_HLIST_NODE(&delayed.node);
2017 spin_lock_irq(¤t->sighand->siglock);
2018 if (!(clone_flags & CLONE_THREAD))
2019 hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2020 recalc_sigpending();
2021 spin_unlock_irq(¤t->sighand->siglock);
2022 retval = -ERESTARTNOINTR;
2023 if (task_sigpending(current))
2027 p = dup_task_struct(current, node);
2030 if (args->io_thread) {
2032 * Mark us an IO worker, and block any signal that isn't
2035 p->flags |= PF_IO_WORKER;
2036 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2040 * This _must_ happen before we call free_task(), i.e. before we jump
2041 * to any of the bad_fork_* labels. This is to avoid freeing
2042 * p->set_child_tid which is (ab)used as a kthread's data pointer for
2043 * kernel threads (PF_KTHREAD).
2045 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2047 * Clear TID on mm_release()?
2049 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2051 ftrace_graph_init_task(p);
2053 rt_mutex_init_task(p);
2055 lockdep_assert_irqs_enabled();
2056 #ifdef CONFIG_PROVE_LOCKING
2057 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2059 retval = copy_creds(p, clone_flags);
2064 if (is_ucounts_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2065 if (p->real_cred->user != INIT_USER &&
2066 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2067 goto bad_fork_cleanup_count;
2069 current->flags &= ~PF_NPROC_EXCEEDED;
2072 * If multiple threads are within copy_process(), then this check
2073 * triggers too late. This doesn't hurt, the check is only there
2074 * to stop root fork bombs.
2077 if (data_race(nr_threads >= max_threads))
2078 goto bad_fork_cleanup_count;
2080 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2081 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2082 p->flags |= PF_FORKNOEXEC;
2083 INIT_LIST_HEAD(&p->children);
2084 INIT_LIST_HEAD(&p->sibling);
2085 rcu_copy_process(p);
2086 p->vfork_done = NULL;
2087 spin_lock_init(&p->alloc_lock);
2089 init_sigpending(&p->pending);
2091 p->utime = p->stime = p->gtime = 0;
2092 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2093 p->utimescaled = p->stimescaled = 0;
2095 prev_cputime_init(&p->prev_cputime);
2097 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2098 seqcount_init(&p->vtime.seqcount);
2099 p->vtime.starttime = 0;
2100 p->vtime.state = VTIME_INACTIVE;
2103 #ifdef CONFIG_IO_URING
2107 #if defined(SPLIT_RSS_COUNTING)
2108 memset(&p->rss_stat, 0, sizeof(p->rss_stat));
2111 p->default_timer_slack_ns = current->timer_slack_ns;
2117 task_io_accounting_init(&p->ioac);
2118 acct_clear_integrals(p);
2120 posix_cputimers_init(&p->posix_cputimers);
2122 p->io_context = NULL;
2123 audit_set_context(p, NULL);
2126 p->mempolicy = mpol_dup(p->mempolicy);
2127 if (IS_ERR(p->mempolicy)) {
2128 retval = PTR_ERR(p->mempolicy);
2129 p->mempolicy = NULL;
2130 goto bad_fork_cleanup_threadgroup_lock;
2133 #ifdef CONFIG_CPUSETS
2134 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2135 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2136 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2138 #ifdef CONFIG_TRACE_IRQFLAGS
2139 memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2140 p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2141 p->irqtrace.softirq_enable_ip = _THIS_IP_;
2142 p->softirqs_enabled = 1;
2143 p->softirq_context = 0;
2146 p->pagefault_disabled = 0;
2148 #ifdef CONFIG_LOCKDEP
2149 lockdep_init_task(p);
2152 #ifdef CONFIG_DEBUG_MUTEXES
2153 p->blocked_on = NULL; /* not blocked yet */
2155 #ifdef CONFIG_BCACHE
2156 p->sequential_io = 0;
2157 p->sequential_io_avg = 0;
2159 #ifdef CONFIG_BPF_SYSCALL
2160 RCU_INIT_POINTER(p->bpf_storage, NULL);
2164 /* Perform scheduler related setup. Assign this task to a CPU. */
2165 retval = sched_fork(clone_flags, p);
2167 goto bad_fork_cleanup_policy;
2169 retval = perf_event_init_task(p, clone_flags);
2171 goto bad_fork_cleanup_policy;
2172 retval = audit_alloc(p);
2174 goto bad_fork_cleanup_perf;
2175 /* copy all the process information */
2177 retval = security_task_alloc(p, clone_flags);
2179 goto bad_fork_cleanup_audit;
2180 retval = copy_semundo(clone_flags, p);
2182 goto bad_fork_cleanup_security;
2183 retval = copy_files(clone_flags, p);
2185 goto bad_fork_cleanup_semundo;
2186 retval = copy_fs(clone_flags, p);
2188 goto bad_fork_cleanup_files;
2189 retval = copy_sighand(clone_flags, p);
2191 goto bad_fork_cleanup_fs;
2192 retval = copy_signal(clone_flags, p);
2194 goto bad_fork_cleanup_sighand;
2195 retval = copy_mm(clone_flags, p);
2197 goto bad_fork_cleanup_signal;
2198 retval = copy_namespaces(clone_flags, p);
2200 goto bad_fork_cleanup_mm;
2201 retval = copy_io(clone_flags, p);
2203 goto bad_fork_cleanup_namespaces;
2204 retval = copy_thread(clone_flags, args->stack, args->stack_size, p, args->tls);
2206 goto bad_fork_cleanup_io;
2208 stackleak_task_init(p);
2210 if (pid != &init_struct_pid) {
2211 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2212 args->set_tid_size);
2214 retval = PTR_ERR(pid);
2215 goto bad_fork_cleanup_thread;
2220 * This has to happen after we've potentially unshared the file
2221 * descriptor table (so that the pidfd doesn't leak into the child
2222 * if the fd table isn't shared).
2224 if (clone_flags & CLONE_PIDFD) {
2225 retval = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
2227 goto bad_fork_free_pid;
2231 pidfile = anon_inode_getfile("[pidfd]", &pidfd_fops, pid,
2232 O_RDWR | O_CLOEXEC);
2233 if (IS_ERR(pidfile)) {
2234 put_unused_fd(pidfd);
2235 retval = PTR_ERR(pidfile);
2236 goto bad_fork_free_pid;
2238 get_pid(pid); /* held by pidfile now */
2240 retval = put_user(pidfd, args->pidfd);
2242 goto bad_fork_put_pidfd;
2251 * sigaltstack should be cleared when sharing the same VM
2253 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2257 * Syscall tracing and stepping should be turned off in the
2258 * child regardless of CLONE_PTRACE.
2260 user_disable_single_step(p);
2261 clear_task_syscall_work(p, SYSCALL_TRACE);
2262 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2263 clear_task_syscall_work(p, SYSCALL_EMU);
2265 clear_tsk_latency_tracing(p);
2267 /* ok, now we should be set up.. */
2268 p->pid = pid_nr(pid);
2269 if (clone_flags & CLONE_THREAD) {
2270 p->group_leader = current->group_leader;
2271 p->tgid = current->tgid;
2273 p->group_leader = p;
2278 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2279 p->dirty_paused_when = 0;
2281 p->pdeath_signal = 0;
2282 INIT_LIST_HEAD(&p->thread_group);
2283 p->task_works = NULL;
2284 clear_posix_cputimers_work(p);
2286 #ifdef CONFIG_KRETPROBES
2287 p->kretprobe_instances.first = NULL;
2291 * Ensure that the cgroup subsystem policies allow the new process to be
2292 * forked. It should be noted that the new process's css_set can be changed
2293 * between here and cgroup_post_fork() if an organisation operation is in
2296 retval = cgroup_can_fork(p, args);
2298 goto bad_fork_put_pidfd;
2301 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2302 * the new task on the correct runqueue. All this *before* the task
2305 * This isn't part of ->can_fork() because while the re-cloning is
2306 * cgroup specific, it unconditionally needs to place the task on a
2309 sched_cgroup_fork(p, args);
2312 * From this point on we must avoid any synchronous user-space
2313 * communication until we take the tasklist-lock. In particular, we do
2314 * not want user-space to be able to predict the process start-time by
2315 * stalling fork(2) after we recorded the start_time but before it is
2316 * visible to the system.
2319 p->start_time = ktime_get_ns();
2320 p->start_boottime = ktime_get_boottime_ns();
2323 * Make it visible to the rest of the system, but dont wake it up yet.
2324 * Need tasklist lock for parent etc handling!
2326 write_lock_irq(&tasklist_lock);
2328 /* CLONE_PARENT re-uses the old parent */
2329 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2330 p->real_parent = current->real_parent;
2331 p->parent_exec_id = current->parent_exec_id;
2332 if (clone_flags & CLONE_THREAD)
2333 p->exit_signal = -1;
2335 p->exit_signal = current->group_leader->exit_signal;
2337 p->real_parent = current;
2338 p->parent_exec_id = current->self_exec_id;
2339 p->exit_signal = args->exit_signal;
2342 klp_copy_process(p);
2346 spin_lock(¤t->sighand->siglock);
2349 * Copy seccomp details explicitly here, in case they were changed
2350 * before holding sighand lock.
2354 rseq_fork(p, clone_flags);
2356 /* Don't start children in a dying pid namespace */
2357 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2359 goto bad_fork_cancel_cgroup;
2362 /* Let kill terminate clone/fork in the middle */
2363 if (fatal_signal_pending(current)) {
2365 goto bad_fork_cancel_cgroup;
2368 init_task_pid_links(p);
2369 if (likely(p->pid)) {
2370 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2372 init_task_pid(p, PIDTYPE_PID, pid);
2373 if (thread_group_leader(p)) {
2374 init_task_pid(p, PIDTYPE_TGID, pid);
2375 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2376 init_task_pid(p, PIDTYPE_SID, task_session(current));
2378 if (is_child_reaper(pid)) {
2379 ns_of_pid(pid)->child_reaper = p;
2380 p->signal->flags |= SIGNAL_UNKILLABLE;
2382 p->signal->shared_pending.signal = delayed.signal;
2383 p->signal->tty = tty_kref_get(current->signal->tty);
2385 * Inherit has_child_subreaper flag under the same
2386 * tasklist_lock with adding child to the process tree
2387 * for propagate_has_child_subreaper optimization.
2389 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2390 p->real_parent->signal->is_child_subreaper;
2391 list_add_tail(&p->sibling, &p->real_parent->children);
2392 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2393 attach_pid(p, PIDTYPE_TGID);
2394 attach_pid(p, PIDTYPE_PGID);
2395 attach_pid(p, PIDTYPE_SID);
2396 __this_cpu_inc(process_counts);
2398 current->signal->nr_threads++;
2399 atomic_inc(¤t->signal->live);
2400 refcount_inc(¤t->signal->sigcnt);
2401 task_join_group_stop(p);
2402 list_add_tail_rcu(&p->thread_group,
2403 &p->group_leader->thread_group);
2404 list_add_tail_rcu(&p->thread_node,
2405 &p->signal->thread_head);
2407 attach_pid(p, PIDTYPE_PID);
2411 hlist_del_init(&delayed.node);
2412 spin_unlock(¤t->sighand->siglock);
2413 syscall_tracepoint_update(p);
2414 write_unlock_irq(&tasklist_lock);
2417 fd_install(pidfd, pidfile);
2419 proc_fork_connector(p);
2421 cgroup_post_fork(p, args);
2424 trace_task_newtask(p, clone_flags);
2425 uprobe_copy_process(p, clone_flags);
2427 copy_oom_score_adj(clone_flags, p);
2431 bad_fork_cancel_cgroup:
2433 spin_unlock(¤t->sighand->siglock);
2434 write_unlock_irq(&tasklist_lock);
2435 cgroup_cancel_fork(p, args);
2437 if (clone_flags & CLONE_PIDFD) {
2439 put_unused_fd(pidfd);
2442 if (pid != &init_struct_pid)
2444 bad_fork_cleanup_thread:
2446 bad_fork_cleanup_io:
2449 bad_fork_cleanup_namespaces:
2450 exit_task_namespaces(p);
2451 bad_fork_cleanup_mm:
2453 mm_clear_owner(p->mm, p);
2456 bad_fork_cleanup_signal:
2457 if (!(clone_flags & CLONE_THREAD))
2458 free_signal_struct(p->signal);
2459 bad_fork_cleanup_sighand:
2460 __cleanup_sighand(p->sighand);
2461 bad_fork_cleanup_fs:
2462 exit_fs(p); /* blocking */
2463 bad_fork_cleanup_files:
2464 exit_files(p); /* blocking */
2465 bad_fork_cleanup_semundo:
2467 bad_fork_cleanup_security:
2468 security_task_free(p);
2469 bad_fork_cleanup_audit:
2471 bad_fork_cleanup_perf:
2472 perf_event_free_task(p);
2473 bad_fork_cleanup_policy:
2474 lockdep_free_task(p);
2476 mpol_put(p->mempolicy);
2477 bad_fork_cleanup_threadgroup_lock:
2479 delayacct_tsk_free(p);
2480 bad_fork_cleanup_count:
2481 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2484 WRITE_ONCE(p->__state, TASK_DEAD);
2486 delayed_free_task(p);
2488 spin_lock_irq(¤t->sighand->siglock);
2489 hlist_del_init(&delayed.node);
2490 spin_unlock_irq(¤t->sighand->siglock);
2491 return ERR_PTR(retval);
2494 static inline void init_idle_pids(struct task_struct *idle)
2498 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2499 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2500 init_task_pid(idle, type, &init_struct_pid);
2504 struct task_struct * __init fork_idle(int cpu)
2506 struct task_struct *task;
2507 struct kernel_clone_args args = {
2511 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2512 if (!IS_ERR(task)) {
2513 init_idle_pids(task);
2514 init_idle(task, cpu);
2520 struct mm_struct *copy_init_mm(void)
2522 return dup_mm(NULL, &init_mm);
2526 * This is like kernel_clone(), but shaved down and tailored to just
2527 * creating io_uring workers. It returns a created task, or an error pointer.
2528 * The returned task is inactive, and the caller must fire it up through
2529 * wake_up_new_task(p). All signals are blocked in the created task.
2531 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2533 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2535 struct kernel_clone_args args = {
2536 .flags = ((lower_32_bits(flags) | CLONE_VM |
2537 CLONE_UNTRACED) & ~CSIGNAL),
2538 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2539 .stack = (unsigned long)fn,
2540 .stack_size = (unsigned long)arg,
2544 return copy_process(NULL, 0, node, &args);
2548 * Ok, this is the main fork-routine.
2550 * It copies the process, and if successful kick-starts
2551 * it and waits for it to finish using the VM if required.
2553 * args->exit_signal is expected to be checked for sanity by the caller.
2555 pid_t kernel_clone(struct kernel_clone_args *args)
2557 u64 clone_flags = args->flags;
2558 struct completion vfork;
2560 struct task_struct *p;
2565 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2566 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2567 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2568 * field in struct clone_args and it still doesn't make sense to have
2569 * them both point at the same memory location. Performing this check
2570 * here has the advantage that we don't need to have a separate helper
2571 * to check for legacy clone().
2573 if ((args->flags & CLONE_PIDFD) &&
2574 (args->flags & CLONE_PARENT_SETTID) &&
2575 (args->pidfd == args->parent_tid))
2579 * Determine whether and which event to report to ptracer. When
2580 * called from kernel_thread or CLONE_UNTRACED is explicitly
2581 * requested, no event is reported; otherwise, report if the event
2582 * for the type of forking is enabled.
2584 if (!(clone_flags & CLONE_UNTRACED)) {
2585 if (clone_flags & CLONE_VFORK)
2586 trace = PTRACE_EVENT_VFORK;
2587 else if (args->exit_signal != SIGCHLD)
2588 trace = PTRACE_EVENT_CLONE;
2590 trace = PTRACE_EVENT_FORK;
2592 if (likely(!ptrace_event_enabled(current, trace)))
2596 p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2597 add_latent_entropy();
2603 * Do this prior waking up the new thread - the thread pointer
2604 * might get invalid after that point, if the thread exits quickly.
2606 trace_sched_process_fork(current, p);
2608 pid = get_task_pid(p, PIDTYPE_PID);
2611 if (clone_flags & CLONE_PARENT_SETTID)
2612 put_user(nr, args->parent_tid);
2614 if (clone_flags & CLONE_VFORK) {
2615 p->vfork_done = &vfork;
2616 init_completion(&vfork);
2620 wake_up_new_task(p);
2622 /* forking complete and child started to run, tell ptracer */
2623 if (unlikely(trace))
2624 ptrace_event_pid(trace, pid);
2626 if (clone_flags & CLONE_VFORK) {
2627 if (!wait_for_vfork_done(p, &vfork))
2628 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2636 * Create a kernel thread.
2638 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
2640 struct kernel_clone_args args = {
2641 .flags = ((lower_32_bits(flags) | CLONE_VM |
2642 CLONE_UNTRACED) & ~CSIGNAL),
2643 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2644 .stack = (unsigned long)fn,
2645 .stack_size = (unsigned long)arg,
2648 return kernel_clone(&args);
2651 #ifdef __ARCH_WANT_SYS_FORK
2652 SYSCALL_DEFINE0(fork)
2655 struct kernel_clone_args args = {
2656 .exit_signal = SIGCHLD,
2659 return kernel_clone(&args);
2661 /* can not support in nommu mode */
2667 #ifdef __ARCH_WANT_SYS_VFORK
2668 SYSCALL_DEFINE0(vfork)
2670 struct kernel_clone_args args = {
2671 .flags = CLONE_VFORK | CLONE_VM,
2672 .exit_signal = SIGCHLD,
2675 return kernel_clone(&args);
2679 #ifdef __ARCH_WANT_SYS_CLONE
2680 #ifdef CONFIG_CLONE_BACKWARDS
2681 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2682 int __user *, parent_tidptr,
2684 int __user *, child_tidptr)
2685 #elif defined(CONFIG_CLONE_BACKWARDS2)
2686 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2687 int __user *, parent_tidptr,
2688 int __user *, child_tidptr,
2690 #elif defined(CONFIG_CLONE_BACKWARDS3)
2691 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2693 int __user *, parent_tidptr,
2694 int __user *, child_tidptr,
2697 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2698 int __user *, parent_tidptr,
2699 int __user *, child_tidptr,
2703 struct kernel_clone_args args = {
2704 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2705 .pidfd = parent_tidptr,
2706 .child_tid = child_tidptr,
2707 .parent_tid = parent_tidptr,
2708 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2713 return kernel_clone(&args);
2717 #ifdef __ARCH_WANT_SYS_CLONE3
2719 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2720 struct clone_args __user *uargs,
2724 struct clone_args args;
2725 pid_t *kset_tid = kargs->set_tid;
2727 BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2728 CLONE_ARGS_SIZE_VER0);
2729 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2730 CLONE_ARGS_SIZE_VER1);
2731 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2732 CLONE_ARGS_SIZE_VER2);
2733 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2735 if (unlikely(usize > PAGE_SIZE))
2737 if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2740 err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2744 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2747 if (unlikely(!args.set_tid && args.set_tid_size > 0))
2750 if (unlikely(args.set_tid && args.set_tid_size == 0))
2754 * Verify that higher 32bits of exit_signal are unset and that
2755 * it is a valid signal
2757 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2758 !valid_signal(args.exit_signal)))
2761 if ((args.flags & CLONE_INTO_CGROUP) &&
2762 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2765 *kargs = (struct kernel_clone_args){
2766 .flags = args.flags,
2767 .pidfd = u64_to_user_ptr(args.pidfd),
2768 .child_tid = u64_to_user_ptr(args.child_tid),
2769 .parent_tid = u64_to_user_ptr(args.parent_tid),
2770 .exit_signal = args.exit_signal,
2771 .stack = args.stack,
2772 .stack_size = args.stack_size,
2774 .set_tid_size = args.set_tid_size,
2775 .cgroup = args.cgroup,
2779 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
2780 (kargs->set_tid_size * sizeof(pid_t))))
2783 kargs->set_tid = kset_tid;
2789 * clone3_stack_valid - check and prepare stack
2790 * @kargs: kernel clone args
2792 * Verify that the stack arguments userspace gave us are sane.
2793 * In addition, set the stack direction for userspace since it's easy for us to
2796 static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
2798 if (kargs->stack == 0) {
2799 if (kargs->stack_size > 0)
2802 if (kargs->stack_size == 0)
2805 if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
2808 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2809 kargs->stack += kargs->stack_size;
2816 static bool clone3_args_valid(struct kernel_clone_args *kargs)
2818 /* Verify that no unknown flags are passed along. */
2820 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
2824 * - make the CLONE_DETACHED bit reusable for clone3
2825 * - make the CSIGNAL bits reusable for clone3
2827 if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
2830 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
2831 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
2834 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
2838 if (!clone3_stack_valid(kargs))
2845 * clone3 - create a new process with specific properties
2846 * @uargs: argument structure
2847 * @size: size of @uargs
2849 * clone3() is the extensible successor to clone()/clone2().
2850 * It takes a struct as argument that is versioned by its size.
2852 * Return: On success, a positive PID for the child process.
2853 * On error, a negative errno number.
2855 SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
2859 struct kernel_clone_args kargs;
2860 pid_t set_tid[MAX_PID_NS_LEVEL];
2862 kargs.set_tid = set_tid;
2864 err = copy_clone_args_from_user(&kargs, uargs, size);
2868 if (!clone3_args_valid(&kargs))
2871 return kernel_clone(&kargs);
2875 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
2877 struct task_struct *leader, *parent, *child;
2880 read_lock(&tasklist_lock);
2881 leader = top = top->group_leader;
2883 for_each_thread(leader, parent) {
2884 list_for_each_entry(child, &parent->children, sibling) {
2885 res = visitor(child, data);
2897 if (leader != top) {
2899 parent = child->real_parent;
2900 leader = parent->group_leader;
2904 read_unlock(&tasklist_lock);
2907 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2908 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2911 static void sighand_ctor(void *data)
2913 struct sighand_struct *sighand = data;
2915 spin_lock_init(&sighand->siglock);
2916 init_waitqueue_head(&sighand->signalfd_wqh);
2919 void __init proc_caches_init(void)
2921 unsigned int mm_size;
2923 sighand_cachep = kmem_cache_create("sighand_cache",
2924 sizeof(struct sighand_struct), 0,
2925 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
2926 SLAB_ACCOUNT, sighand_ctor);
2927 signal_cachep = kmem_cache_create("signal_cache",
2928 sizeof(struct signal_struct), 0,
2929 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2931 files_cachep = kmem_cache_create("files_cache",
2932 sizeof(struct files_struct), 0,
2933 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2935 fs_cachep = kmem_cache_create("fs_cache",
2936 sizeof(struct fs_struct), 0,
2937 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2941 * The mm_cpumask is located at the end of mm_struct, and is
2942 * dynamically sized based on the maximum CPU number this system
2943 * can have, taking hotplug into account (nr_cpu_ids).
2945 mm_size = sizeof(struct mm_struct) + cpumask_size();
2947 mm_cachep = kmem_cache_create_usercopy("mm_struct",
2948 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
2949 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
2950 offsetof(struct mm_struct, saved_auxv),
2951 sizeof_field(struct mm_struct, saved_auxv),
2953 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
2955 nsproxy_cache_init();
2959 * Check constraints on flags passed to the unshare system call.
2961 static int check_unshare_flags(unsigned long unshare_flags)
2963 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
2964 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
2965 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
2966 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
2970 * Not implemented, but pretend it works if there is nothing
2971 * to unshare. Note that unsharing the address space or the
2972 * signal handlers also need to unshare the signal queues (aka
2975 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
2976 if (!thread_group_empty(current))
2979 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
2980 if (refcount_read(¤t->sighand->count) > 1)
2983 if (unshare_flags & CLONE_VM) {
2984 if (!current_is_single_threaded())
2992 * Unshare the filesystem structure if it is being shared
2994 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
2996 struct fs_struct *fs = current->fs;
2998 if (!(unshare_flags & CLONE_FS) || !fs)
3001 /* don't need lock here; in the worst case we'll do useless copy */
3005 *new_fsp = copy_fs_struct(fs);
3013 * Unshare file descriptor table if it is being shared
3015 int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3016 struct files_struct **new_fdp)
3018 struct files_struct *fd = current->files;
3021 if ((unshare_flags & CLONE_FILES) &&
3022 (fd && atomic_read(&fd->count) > 1)) {
3023 *new_fdp = dup_fd(fd, max_fds, &error);
3032 * unshare allows a process to 'unshare' part of the process
3033 * context which was originally shared using clone. copy_*
3034 * functions used by kernel_clone() cannot be used here directly
3035 * because they modify an inactive task_struct that is being
3036 * constructed. Here we are modifying the current, active,
3039 int ksys_unshare(unsigned long unshare_flags)
3041 struct fs_struct *fs, *new_fs = NULL;
3042 struct files_struct *fd, *new_fd = NULL;
3043 struct cred *new_cred = NULL;
3044 struct nsproxy *new_nsproxy = NULL;
3049 * If unsharing a user namespace must also unshare the thread group
3050 * and unshare the filesystem root and working directories.
3052 if (unshare_flags & CLONE_NEWUSER)
3053 unshare_flags |= CLONE_THREAD | CLONE_FS;
3055 * If unsharing vm, must also unshare signal handlers.
3057 if (unshare_flags & CLONE_VM)
3058 unshare_flags |= CLONE_SIGHAND;
3060 * If unsharing a signal handlers, must also unshare the signal queues.
3062 if (unshare_flags & CLONE_SIGHAND)
3063 unshare_flags |= CLONE_THREAD;
3065 * If unsharing namespace, must also unshare filesystem information.
3067 if (unshare_flags & CLONE_NEWNS)
3068 unshare_flags |= CLONE_FS;
3070 err = check_unshare_flags(unshare_flags);
3072 goto bad_unshare_out;
3074 * CLONE_NEWIPC must also detach from the undolist: after switching
3075 * to a new ipc namespace, the semaphore arrays from the old
3076 * namespace are unreachable.
3078 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3080 err = unshare_fs(unshare_flags, &new_fs);
3082 goto bad_unshare_out;
3083 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3085 goto bad_unshare_cleanup_fs;
3086 err = unshare_userns(unshare_flags, &new_cred);
3088 goto bad_unshare_cleanup_fd;
3089 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3092 goto bad_unshare_cleanup_cred;
3095 err = set_cred_ucounts(new_cred);
3097 goto bad_unshare_cleanup_cred;
3100 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3103 * CLONE_SYSVSEM is equivalent to sys_exit().
3107 if (unshare_flags & CLONE_NEWIPC) {
3108 /* Orphan segments in old ns (see sem above). */
3110 shm_init_task(current);
3114 switch_task_namespaces(current, new_nsproxy);
3120 spin_lock(&fs->lock);
3121 current->fs = new_fs;
3126 spin_unlock(&fs->lock);
3130 fd = current->files;
3131 current->files = new_fd;
3135 task_unlock(current);
3138 /* Install the new user namespace */
3139 commit_creds(new_cred);
3144 perf_event_namespaces(current);
3146 bad_unshare_cleanup_cred:
3149 bad_unshare_cleanup_fd:
3151 put_files_struct(new_fd);
3153 bad_unshare_cleanup_fs:
3155 free_fs_struct(new_fs);
3161 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3163 return ksys_unshare(unshare_flags);
3167 * Helper to unshare the files of the current task.
3168 * We don't want to expose copy_files internals to
3169 * the exec layer of the kernel.
3172 int unshare_files(void)
3174 struct task_struct *task = current;
3175 struct files_struct *old, *copy = NULL;
3178 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3186 put_files_struct(old);
3190 int sysctl_max_threads(struct ctl_table *table, int write,
3191 void *buffer, size_t *lenp, loff_t *ppos)
3195 int threads = max_threads;
3197 int max = MAX_THREADS;
3204 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3208 max_threads = threads;