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/kmsan.h>
41 #include <linux/binfmts.h>
42 #include <linux/mman.h>
43 #include <linux/mmu_notifier.h>
46 #include <linux/mm_inline.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/syscall_user_dispatch.h>
57 #include <linux/jiffies.h>
58 #include <linux/futex.h>
59 #include <linux/compat.h>
60 #include <linux/kthread.h>
61 #include <linux/task_io_accounting_ops.h>
62 #include <linux/rcupdate.h>
63 #include <linux/ptrace.h>
64 #include <linux/mount.h>
65 #include <linux/audit.h>
66 #include <linux/memcontrol.h>
67 #include <linux/ftrace.h>
68 #include <linux/proc_fs.h>
69 #include <linux/profile.h>
70 #include <linux/rmap.h>
71 #include <linux/ksm.h>
72 #include <linux/acct.h>
73 #include <linux/userfaultfd_k.h>
74 #include <linux/tsacct_kern.h>
75 #include <linux/cn_proc.h>
76 #include <linux/freezer.h>
77 #include <linux/delayacct.h>
78 #include <linux/taskstats_kern.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/stackprotector.h>
101 #include <linux/user_events.h>
102 #include <linux/iommu.h>
103 #include <linux/rseq.h>
104 #include <uapi/linux/pidfd.h>
105 #include <linux/pidfs.h>
107 #include <asm/pgalloc.h>
108 #include <linux/uaccess.h>
109 #include <asm/mmu_context.h>
110 #include <asm/cacheflush.h>
111 #include <asm/tlbflush.h>
113 #include <trace/events/sched.h>
115 #define CREATE_TRACE_POINTS
116 #include <trace/events/task.h>
119 * Minimum number of threads to boot the kernel
121 #define MIN_THREADS 20
124 * Maximum number of threads
126 #define MAX_THREADS FUTEX_TID_MASK
129 * Protected counters by write_lock_irq(&tasklist_lock)
131 unsigned long total_forks; /* Handle normal Linux uptimes. */
132 int nr_threads; /* The idle threads do not count.. */
134 static int max_threads; /* tunable limit on nr_threads */
136 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
138 static const char * const resident_page_types[] = {
139 NAMED_ARRAY_INDEX(MM_FILEPAGES),
140 NAMED_ARRAY_INDEX(MM_ANONPAGES),
141 NAMED_ARRAY_INDEX(MM_SWAPENTS),
142 NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
145 DEFINE_PER_CPU(unsigned long, process_counts) = 0;
147 __cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
149 #ifdef CONFIG_PROVE_RCU
150 int lockdep_tasklist_lock_is_held(void)
152 return lockdep_is_held(&tasklist_lock);
154 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
155 #endif /* #ifdef CONFIG_PROVE_RCU */
157 int nr_processes(void)
162 for_each_possible_cpu(cpu)
163 total += per_cpu(process_counts, cpu);
168 void __weak arch_release_task_struct(struct task_struct *tsk)
172 static struct kmem_cache *task_struct_cachep;
174 static inline struct task_struct *alloc_task_struct_node(int node)
176 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
179 static inline void free_task_struct(struct task_struct *tsk)
181 kmem_cache_free(task_struct_cachep, tsk);
185 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
186 * kmemcache based allocator.
188 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
190 # ifdef CONFIG_VMAP_STACK
192 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
193 * flush. Try to minimize the number of calls by caching stacks.
195 #define NR_CACHED_STACKS 2
196 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
200 struct vm_struct *stack_vm_area;
203 static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
207 for (i = 0; i < NR_CACHED_STACKS; i++) {
208 if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
215 static void thread_stack_free_rcu(struct rcu_head *rh)
217 struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
219 if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
225 static void thread_stack_delayed_free(struct task_struct *tsk)
227 struct vm_stack *vm_stack = tsk->stack;
229 vm_stack->stack_vm_area = tsk->stack_vm_area;
230 call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
233 static int free_vm_stack_cache(unsigned int cpu)
235 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
238 for (i = 0; i < NR_CACHED_STACKS; i++) {
239 struct vm_struct *vm_stack = cached_vm_stacks[i];
244 vfree(vm_stack->addr);
245 cached_vm_stacks[i] = NULL;
251 static int memcg_charge_kernel_stack(struct vm_struct *vm)
257 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
259 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
260 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
267 for (i = 0; i < nr_charged; i++)
268 memcg_kmem_uncharge_page(vm->pages[i], 0);
272 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
274 struct vm_struct *vm;
278 for (i = 0; i < NR_CACHED_STACKS; i++) {
281 s = this_cpu_xchg(cached_stacks[i], NULL);
286 /* Reset stack metadata. */
287 kasan_unpoison_range(s->addr, THREAD_SIZE);
289 stack = kasan_reset_tag(s->addr);
291 /* Clear stale pointers from reused stack. */
292 memset(stack, 0, THREAD_SIZE);
294 if (memcg_charge_kernel_stack(s)) {
299 tsk->stack_vm_area = s;
305 * Allocated stacks are cached and later reused by new threads,
306 * so memcg accounting is performed manually on assigning/releasing
307 * stacks to tasks. Drop __GFP_ACCOUNT.
309 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
310 VMALLOC_START, VMALLOC_END,
311 THREADINFO_GFP & ~__GFP_ACCOUNT,
313 0, node, __builtin_return_address(0));
317 vm = find_vm_area(stack);
318 if (memcg_charge_kernel_stack(vm)) {
323 * We can't call find_vm_area() in interrupt context, and
324 * free_thread_stack() can be called in interrupt context,
325 * so cache the vm_struct.
327 tsk->stack_vm_area = vm;
328 stack = kasan_reset_tag(stack);
333 static void free_thread_stack(struct task_struct *tsk)
335 if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
336 thread_stack_delayed_free(tsk);
339 tsk->stack_vm_area = NULL;
342 # else /* !CONFIG_VMAP_STACK */
344 static void thread_stack_free_rcu(struct rcu_head *rh)
346 __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
349 static void thread_stack_delayed_free(struct task_struct *tsk)
351 struct rcu_head *rh = tsk->stack;
353 call_rcu(rh, thread_stack_free_rcu);
356 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
358 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
362 tsk->stack = kasan_reset_tag(page_address(page));
368 static void free_thread_stack(struct task_struct *tsk)
370 thread_stack_delayed_free(tsk);
374 # endif /* CONFIG_VMAP_STACK */
375 # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
377 static struct kmem_cache *thread_stack_cache;
379 static void thread_stack_free_rcu(struct rcu_head *rh)
381 kmem_cache_free(thread_stack_cache, rh);
384 static void thread_stack_delayed_free(struct task_struct *tsk)
386 struct rcu_head *rh = tsk->stack;
388 call_rcu(rh, thread_stack_free_rcu);
391 static int alloc_thread_stack_node(struct task_struct *tsk, int node)
393 unsigned long *stack;
394 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
395 stack = kasan_reset_tag(stack);
397 return stack ? 0 : -ENOMEM;
400 static void free_thread_stack(struct task_struct *tsk)
402 thread_stack_delayed_free(tsk);
406 void thread_stack_cache_init(void)
408 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
409 THREAD_SIZE, THREAD_SIZE, 0, 0,
411 BUG_ON(thread_stack_cache == NULL);
414 # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
416 /* SLAB cache for signal_struct structures (tsk->signal) */
417 static struct kmem_cache *signal_cachep;
419 /* SLAB cache for sighand_struct structures (tsk->sighand) */
420 struct kmem_cache *sighand_cachep;
422 /* SLAB cache for files_struct structures (tsk->files) */
423 struct kmem_cache *files_cachep;
425 /* SLAB cache for fs_struct structures (tsk->fs) */
426 struct kmem_cache *fs_cachep;
428 /* SLAB cache for vm_area_struct structures */
429 static struct kmem_cache *vm_area_cachep;
431 /* SLAB cache for mm_struct structures (tsk->mm) */
432 static struct kmem_cache *mm_cachep;
434 #ifdef CONFIG_PER_VMA_LOCK
436 /* SLAB cache for vm_area_struct.lock */
437 static struct kmem_cache *vma_lock_cachep;
439 static bool vma_lock_alloc(struct vm_area_struct *vma)
441 vma->vm_lock = kmem_cache_alloc(vma_lock_cachep, GFP_KERNEL);
445 init_rwsem(&vma->vm_lock->lock);
446 vma->vm_lock_seq = -1;
451 static inline void vma_lock_free(struct vm_area_struct *vma)
453 kmem_cache_free(vma_lock_cachep, vma->vm_lock);
456 #else /* CONFIG_PER_VMA_LOCK */
458 static inline bool vma_lock_alloc(struct vm_area_struct *vma) { return true; }
459 static inline void vma_lock_free(struct vm_area_struct *vma) {}
461 #endif /* CONFIG_PER_VMA_LOCK */
463 struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
465 struct vm_area_struct *vma;
467 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
472 if (!vma_lock_alloc(vma)) {
473 kmem_cache_free(vm_area_cachep, vma);
480 struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
482 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
487 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
488 ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
490 * orig->shared.rb may be modified concurrently, but the clone
491 * will be reinitialized.
493 data_race(memcpy(new, orig, sizeof(*new)));
494 if (!vma_lock_alloc(new)) {
495 kmem_cache_free(vm_area_cachep, new);
498 INIT_LIST_HEAD(&new->anon_vma_chain);
499 vma_numab_state_init(new);
500 dup_anon_vma_name(orig, new);
505 void __vm_area_free(struct vm_area_struct *vma)
507 vma_numab_state_free(vma);
508 free_anon_vma_name(vma);
510 kmem_cache_free(vm_area_cachep, vma);
513 #ifdef CONFIG_PER_VMA_LOCK
514 static void vm_area_free_rcu_cb(struct rcu_head *head)
516 struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
519 /* The vma should not be locked while being destroyed. */
520 VM_BUG_ON_VMA(rwsem_is_locked(&vma->vm_lock->lock), vma);
525 void vm_area_free(struct vm_area_struct *vma)
527 #ifdef CONFIG_PER_VMA_LOCK
528 call_rcu(&vma->vm_rcu, vm_area_free_rcu_cb);
534 static void account_kernel_stack(struct task_struct *tsk, int account)
536 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
537 struct vm_struct *vm = task_stack_vm_area(tsk);
540 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
541 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
542 account * (PAGE_SIZE / 1024));
544 void *stack = task_stack_page(tsk);
546 /* All stack pages are in the same node. */
547 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
548 account * (THREAD_SIZE / 1024));
552 void exit_task_stack_account(struct task_struct *tsk)
554 account_kernel_stack(tsk, -1);
556 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
557 struct vm_struct *vm;
560 vm = task_stack_vm_area(tsk);
561 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
562 memcg_kmem_uncharge_page(vm->pages[i], 0);
566 static void release_task_stack(struct task_struct *tsk)
568 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
569 return; /* Better to leak the stack than to free prematurely */
571 free_thread_stack(tsk);
574 #ifdef CONFIG_THREAD_INFO_IN_TASK
575 void put_task_stack(struct task_struct *tsk)
577 if (refcount_dec_and_test(&tsk->stack_refcount))
578 release_task_stack(tsk);
582 void free_task(struct task_struct *tsk)
584 #ifdef CONFIG_SECCOMP
585 WARN_ON_ONCE(tsk->seccomp.filter);
587 release_user_cpus_ptr(tsk);
590 #ifndef CONFIG_THREAD_INFO_IN_TASK
592 * The task is finally done with both the stack and thread_info,
595 release_task_stack(tsk);
598 * If the task had a separate stack allocation, it should be gone
601 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
603 rt_mutex_debug_task_free(tsk);
604 ftrace_graph_exit_task(tsk);
605 arch_release_task_struct(tsk);
606 if (tsk->flags & PF_KTHREAD)
607 free_kthread_struct(tsk);
608 bpf_task_storage_free(tsk);
609 free_task_struct(tsk);
611 EXPORT_SYMBOL(free_task);
613 static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
615 struct file *exe_file;
617 exe_file = get_mm_exe_file(oldmm);
618 RCU_INIT_POINTER(mm->exe_file, exe_file);
620 * We depend on the oldmm having properly denied write access to the
623 if (exe_file && deny_write_access(exe_file))
624 pr_warn_once("deny_write_access() failed in %s\n", __func__);
628 static __latent_entropy int dup_mmap(struct mm_struct *mm,
629 struct mm_struct *oldmm)
631 struct vm_area_struct *mpnt, *tmp;
633 unsigned long charge = 0;
635 VMA_ITERATOR(vmi, mm, 0);
637 uprobe_start_dup_mmap();
638 if (mmap_write_lock_killable(oldmm)) {
640 goto fail_uprobe_end;
642 flush_cache_dup_mm(oldmm);
643 uprobe_dup_mmap(oldmm, mm);
645 * Not linked in yet - no deadlock potential:
647 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
649 /* No ordering required: file already has been exposed. */
650 dup_mm_exe_file(mm, oldmm);
652 mm->total_vm = oldmm->total_vm;
653 mm->data_vm = oldmm->data_vm;
654 mm->exec_vm = oldmm->exec_vm;
655 mm->stack_vm = oldmm->stack_vm;
657 retval = ksm_fork(mm, oldmm);
660 khugepaged_fork(mm, oldmm);
662 /* Use __mt_dup() to efficiently build an identical maple tree. */
663 retval = __mt_dup(&oldmm->mm_mt, &mm->mm_mt, GFP_KERNEL);
664 if (unlikely(retval))
667 mt_clear_in_rcu(vmi.mas.tree);
668 for_each_vma(vmi, mpnt) {
671 vma_start_write(mpnt);
672 if (mpnt->vm_flags & VM_DONTCOPY) {
673 retval = vma_iter_clear_gfp(&vmi, mpnt->vm_start,
674 mpnt->vm_end, GFP_KERNEL);
678 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
683 * Don't duplicate many vmas if we've been oom-killed (for
686 if (fatal_signal_pending(current)) {
690 if (mpnt->vm_flags & VM_ACCOUNT) {
691 unsigned long len = vma_pages(mpnt);
693 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
697 tmp = vm_area_dup(mpnt);
700 retval = vma_dup_policy(mpnt, tmp);
702 goto fail_nomem_policy;
704 retval = dup_userfaultfd(tmp, &uf);
706 goto fail_nomem_anon_vma_fork;
707 if (tmp->vm_flags & VM_WIPEONFORK) {
709 * VM_WIPEONFORK gets a clean slate in the child.
710 * Don't prepare anon_vma until fault since we don't
711 * copy page for current vma.
713 tmp->anon_vma = NULL;
714 } else if (anon_vma_fork(tmp, mpnt))
715 goto fail_nomem_anon_vma_fork;
716 vm_flags_clear(tmp, VM_LOCKED_MASK);
719 struct address_space *mapping = file->f_mapping;
722 i_mmap_lock_write(mapping);
723 if (vma_is_shared_maywrite(tmp))
724 mapping_allow_writable(mapping);
725 flush_dcache_mmap_lock(mapping);
726 /* insert tmp into the share list, just after mpnt */
727 vma_interval_tree_insert_after(tmp, mpnt,
729 flush_dcache_mmap_unlock(mapping);
730 i_mmap_unlock_write(mapping);
734 * Copy/update hugetlb private vma information.
736 if (is_vm_hugetlb_page(tmp))
737 hugetlb_dup_vma_private(tmp);
740 * Link the vma into the MT. After using __mt_dup(), memory
741 * allocation is not necessary here, so it cannot fail.
743 vma_iter_bulk_store(&vmi, tmp);
746 if (!(tmp->vm_flags & VM_WIPEONFORK))
747 retval = copy_page_range(tmp, mpnt);
749 if (tmp->vm_ops && tmp->vm_ops->open)
750 tmp->vm_ops->open(tmp);
753 mpnt = vma_next(&vmi);
757 /* a new mm has just been created */
758 retval = arch_dup_mmap(oldmm, mm);
762 mt_set_in_rcu(vmi.mas.tree);
765 * The entire maple tree has already been duplicated. If the
766 * mmap duplication fails, mark the failure point with
767 * XA_ZERO_ENTRY. In exit_mmap(), if this marker is encountered,
768 * stop releasing VMAs that have not been duplicated after this
771 mas_set_range(&vmi.mas, mpnt->vm_start, mpnt->vm_end - 1);
772 mas_store(&vmi.mas, XA_ZERO_ENTRY);
775 mmap_write_unlock(mm);
777 mmap_write_unlock(oldmm);
778 dup_userfaultfd_complete(&uf);
780 uprobe_end_dup_mmap();
783 fail_nomem_anon_vma_fork:
784 mpol_put(vma_policy(tmp));
789 vm_unacct_memory(charge);
793 static inline int mm_alloc_pgd(struct mm_struct *mm)
795 mm->pgd = pgd_alloc(mm);
796 if (unlikely(!mm->pgd))
801 static inline void mm_free_pgd(struct mm_struct *mm)
803 pgd_free(mm, mm->pgd);
806 static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
808 mmap_write_lock(oldmm);
809 dup_mm_exe_file(mm, oldmm);
810 mmap_write_unlock(oldmm);
813 #define mm_alloc_pgd(mm) (0)
814 #define mm_free_pgd(mm)
815 #endif /* CONFIG_MMU */
817 static void check_mm(struct mm_struct *mm)
821 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
822 "Please make sure 'struct resident_page_types[]' is updated as well");
824 for (i = 0; i < NR_MM_COUNTERS; i++) {
825 long x = percpu_counter_sum(&mm->rss_stat[i]);
828 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
829 mm, resident_page_types[i], x);
832 if (mm_pgtables_bytes(mm))
833 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
834 mm_pgtables_bytes(mm));
836 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
837 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
841 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
842 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
844 static void do_check_lazy_tlb(void *arg)
846 struct mm_struct *mm = arg;
848 WARN_ON_ONCE(current->active_mm == mm);
851 static void do_shoot_lazy_tlb(void *arg)
853 struct mm_struct *mm = arg;
855 if (current->active_mm == mm) {
856 WARN_ON_ONCE(current->mm);
857 current->active_mm = &init_mm;
858 switch_mm(mm, &init_mm, current);
862 static void cleanup_lazy_tlbs(struct mm_struct *mm)
864 if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN)) {
866 * In this case, lazy tlb mms are refounted and would not reach
867 * __mmdrop until all CPUs have switched away and mmdrop()ed.
873 * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it
874 * requires lazy mm users to switch to another mm when the refcount
875 * drops to zero, before the mm is freed. This requires IPIs here to
876 * switch kernel threads to init_mm.
878 * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm
879 * switch with the final userspace teardown TLB flush which leaves the
880 * mm lazy on this CPU but no others, reducing the need for additional
881 * IPIs here. There are cases where a final IPI is still required here,
882 * such as the final mmdrop being performed on a different CPU than the
883 * one exiting, or kernel threads using the mm when userspace exits.
885 * IPI overheads have not found to be expensive, but they could be
886 * reduced in a number of possible ways, for example (roughly
887 * increasing order of complexity):
888 * - The last lazy reference created by exit_mm() could instead switch
889 * to init_mm, however it's probable this will run on the same CPU
890 * immediately afterwards, so this may not reduce IPIs much.
891 * - A batch of mms requiring IPIs could be gathered and freed at once.
892 * - CPUs store active_mm where it can be remotely checked without a
893 * lock, to filter out false-positives in the cpumask.
894 * - After mm_users or mm_count reaches zero, switching away from the
895 * mm could clear mm_cpumask to reduce some IPIs, perhaps together
896 * with some batching or delaying of the final IPIs.
897 * - A delayed freeing and RCU-like quiescing sequence based on mm
898 * switching to avoid IPIs completely.
900 on_each_cpu_mask(mm_cpumask(mm), do_shoot_lazy_tlb, (void *)mm, 1);
901 if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES))
902 on_each_cpu(do_check_lazy_tlb, (void *)mm, 1);
906 * Called when the last reference to the mm
907 * is dropped: either by a lazy thread or by
908 * mmput. Free the page directory and the mm.
910 void __mmdrop(struct mm_struct *mm)
912 BUG_ON(mm == &init_mm);
913 WARN_ON_ONCE(mm == current->mm);
915 /* Ensure no CPUs are using this as their lazy tlb mm */
916 cleanup_lazy_tlbs(mm);
918 WARN_ON_ONCE(mm == current->active_mm);
921 mmu_notifier_subscriptions_destroy(mm);
923 put_user_ns(mm->user_ns);
926 percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS);
930 EXPORT_SYMBOL_GPL(__mmdrop);
932 static void mmdrop_async_fn(struct work_struct *work)
934 struct mm_struct *mm;
936 mm = container_of(work, struct mm_struct, async_put_work);
940 static void mmdrop_async(struct mm_struct *mm)
942 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
943 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
944 schedule_work(&mm->async_put_work);
948 static inline void free_signal_struct(struct signal_struct *sig)
950 taskstats_tgid_free(sig);
951 sched_autogroup_exit(sig);
953 * __mmdrop is not safe to call from softirq context on x86 due to
954 * pgd_dtor so postpone it to the async context
957 mmdrop_async(sig->oom_mm);
958 kmem_cache_free(signal_cachep, sig);
961 static inline void put_signal_struct(struct signal_struct *sig)
963 if (refcount_dec_and_test(&sig->sigcnt))
964 free_signal_struct(sig);
967 void __put_task_struct(struct task_struct *tsk)
969 WARN_ON(!tsk->exit_state);
970 WARN_ON(refcount_read(&tsk->usage));
971 WARN_ON(tsk == current);
975 task_numa_free(tsk, true);
976 security_task_free(tsk);
978 delayacct_tsk_free(tsk);
979 put_signal_struct(tsk->signal);
980 sched_core_free(tsk);
983 EXPORT_SYMBOL_GPL(__put_task_struct);
985 void __put_task_struct_rcu_cb(struct rcu_head *rhp)
987 struct task_struct *task = container_of(rhp, struct task_struct, rcu);
989 __put_task_struct(task);
991 EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb);
993 void __init __weak arch_task_cache_init(void) { }
998 static void set_max_threads(unsigned int max_threads_suggested)
1001 unsigned long nr_pages = totalram_pages();
1004 * The number of threads shall be limited such that the thread
1005 * structures may only consume a small part of the available memory.
1007 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
1008 threads = MAX_THREADS;
1010 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
1011 (u64) THREAD_SIZE * 8UL);
1013 if (threads > max_threads_suggested)
1014 threads = max_threads_suggested;
1016 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
1019 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
1020 /* Initialized by the architecture: */
1021 int arch_task_struct_size __read_mostly;
1024 static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
1026 /* Fetch thread_struct whitelist for the architecture. */
1027 arch_thread_struct_whitelist(offset, size);
1030 * Handle zero-sized whitelist or empty thread_struct, otherwise
1031 * adjust offset to position of thread_struct in task_struct.
1033 if (unlikely(*size == 0))
1036 *offset += offsetof(struct task_struct, thread);
1039 void __init fork_init(void)
1042 #ifndef ARCH_MIN_TASKALIGN
1043 #define ARCH_MIN_TASKALIGN 0
1045 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
1046 unsigned long useroffset, usersize;
1048 /* create a slab on which task_structs can be allocated */
1049 task_struct_whitelist(&useroffset, &usersize);
1050 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
1051 arch_task_struct_size, align,
1052 SLAB_PANIC|SLAB_ACCOUNT,
1053 useroffset, usersize, NULL);
1055 /* do the arch specific task caches init */
1056 arch_task_cache_init();
1058 set_max_threads(MAX_THREADS);
1060 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
1061 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
1062 init_task.signal->rlim[RLIMIT_SIGPENDING] =
1063 init_task.signal->rlim[RLIMIT_NPROC];
1065 for (i = 0; i < UCOUNT_COUNTS; i++)
1066 init_user_ns.ucount_max[i] = max_threads/2;
1068 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
1069 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
1070 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
1071 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
1073 #ifdef CONFIG_VMAP_STACK
1074 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
1075 NULL, free_vm_stack_cache);
1080 lockdep_init_task(&init_task);
1084 int __weak arch_dup_task_struct(struct task_struct *dst,
1085 struct task_struct *src)
1091 void set_task_stack_end_magic(struct task_struct *tsk)
1093 unsigned long *stackend;
1095 stackend = end_of_stack(tsk);
1096 *stackend = STACK_END_MAGIC; /* for overflow detection */
1099 static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
1101 struct task_struct *tsk;
1104 if (node == NUMA_NO_NODE)
1105 node = tsk_fork_get_node(orig);
1106 tsk = alloc_task_struct_node(node);
1110 err = arch_dup_task_struct(tsk, orig);
1114 err = alloc_thread_stack_node(tsk, node);
1118 #ifdef CONFIG_THREAD_INFO_IN_TASK
1119 refcount_set(&tsk->stack_refcount, 1);
1121 account_kernel_stack(tsk, 1);
1123 err = scs_prepare(tsk, node);
1127 #ifdef CONFIG_SECCOMP
1129 * We must handle setting up seccomp filters once we're under
1130 * the sighand lock in case orig has changed between now and
1131 * then. Until then, filter must be NULL to avoid messing up
1132 * the usage counts on the error path calling free_task.
1134 tsk->seccomp.filter = NULL;
1137 setup_thread_stack(tsk, orig);
1138 clear_user_return_notifier(tsk);
1139 clear_tsk_need_resched(tsk);
1140 set_task_stack_end_magic(tsk);
1141 clear_syscall_work_syscall_user_dispatch(tsk);
1143 #ifdef CONFIG_STACKPROTECTOR
1144 tsk->stack_canary = get_random_canary();
1146 if (orig->cpus_ptr == &orig->cpus_mask)
1147 tsk->cpus_ptr = &tsk->cpus_mask;
1148 dup_user_cpus_ptr(tsk, orig, node);
1151 * One for the user space visible state that goes away when reaped.
1152 * One for the scheduler.
1154 refcount_set(&tsk->rcu_users, 2);
1155 /* One for the rcu users */
1156 refcount_set(&tsk->usage, 1);
1157 #ifdef CONFIG_BLK_DEV_IO_TRACE
1158 tsk->btrace_seq = 0;
1160 tsk->splice_pipe = NULL;
1161 tsk->task_frag.page = NULL;
1162 tsk->wake_q.next = NULL;
1163 tsk->worker_private = NULL;
1165 kcov_task_init(tsk);
1166 kmsan_task_create(tsk);
1167 kmap_local_fork(tsk);
1169 #ifdef CONFIG_FAULT_INJECTION
1173 #ifdef CONFIG_BLK_CGROUP
1174 tsk->throttle_disk = NULL;
1175 tsk->use_memdelay = 0;
1178 #ifdef CONFIG_ARCH_HAS_CPU_PASID
1179 tsk->pasid_activated = 0;
1183 tsk->active_memcg = NULL;
1186 #ifdef CONFIG_CPU_SUP_INTEL
1187 tsk->reported_split_lock = 0;
1190 #ifdef CONFIG_SCHED_MM_CID
1192 tsk->last_mm_cid = -1;
1193 tsk->mm_cid_active = 0;
1194 tsk->migrate_from_cpu = -1;
1199 exit_task_stack_account(tsk);
1200 free_thread_stack(tsk);
1202 free_task_struct(tsk);
1206 __cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1208 static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1210 static int __init coredump_filter_setup(char *s)
1212 default_dump_filter =
1213 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1214 MMF_DUMP_FILTER_MASK;
1218 __setup("coredump_filter=", coredump_filter_setup);
1220 #include <linux/init_task.h>
1222 static void mm_init_aio(struct mm_struct *mm)
1225 spin_lock_init(&mm->ioctx_lock);
1226 mm->ioctx_table = NULL;
1230 static __always_inline void mm_clear_owner(struct mm_struct *mm,
1231 struct task_struct *p)
1235 WRITE_ONCE(mm->owner, NULL);
1239 static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1246 static void mm_init_uprobes_state(struct mm_struct *mm)
1248 #ifdef CONFIG_UPROBES
1249 mm->uprobes_state.xol_area = NULL;
1253 static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1254 struct user_namespace *user_ns)
1256 mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
1257 mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
1258 atomic_set(&mm->mm_users, 1);
1259 atomic_set(&mm->mm_count, 1);
1260 seqcount_init(&mm->write_protect_seq);
1262 INIT_LIST_HEAD(&mm->mmlist);
1263 #ifdef CONFIG_PER_VMA_LOCK
1264 mm->mm_lock_seq = 0;
1266 mm_pgtables_bytes_init(mm);
1269 atomic64_set(&mm->pinned_vm, 0);
1270 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1271 spin_lock_init(&mm->page_table_lock);
1272 spin_lock_init(&mm->arg_lock);
1273 mm_init_cpumask(mm);
1275 mm_init_owner(mm, p);
1277 RCU_INIT_POINTER(mm->exe_file, NULL);
1278 mmu_notifier_subscriptions_init(mm);
1279 init_tlb_flush_pending(mm);
1280 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1281 mm->pmd_huge_pte = NULL;
1283 mm_init_uprobes_state(mm);
1284 hugetlb_count_init(mm);
1287 mm->flags = mmf_init_flags(current->mm->flags);
1288 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1290 mm->flags = default_dump_filter;
1294 if (mm_alloc_pgd(mm))
1297 if (init_new_context(p, mm))
1298 goto fail_nocontext;
1300 if (mm_alloc_cid(mm))
1303 if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT,
1307 mm->user_ns = get_user_ns(user_ns);
1308 lru_gen_init_mm(mm);
1314 destroy_context(mm);
1323 * Allocate and initialize an mm_struct.
1325 struct mm_struct *mm_alloc(void)
1327 struct mm_struct *mm;
1333 memset(mm, 0, sizeof(*mm));
1334 return mm_init(mm, current, current_user_ns());
1337 static inline void __mmput(struct mm_struct *mm)
1339 VM_BUG_ON(atomic_read(&mm->mm_users));
1341 uprobe_clear_state(mm);
1344 khugepaged_exit(mm); /* must run before exit_mmap */
1346 mm_put_huge_zero_page(mm);
1347 set_mm_exe_file(mm, NULL);
1348 if (!list_empty(&mm->mmlist)) {
1349 spin_lock(&mmlist_lock);
1350 list_del(&mm->mmlist);
1351 spin_unlock(&mmlist_lock);
1354 module_put(mm->binfmt->module);
1360 * Decrement the use count and release all resources for an mm.
1362 void mmput(struct mm_struct *mm)
1366 if (atomic_dec_and_test(&mm->mm_users))
1369 EXPORT_SYMBOL_GPL(mmput);
1372 static void mmput_async_fn(struct work_struct *work)
1374 struct mm_struct *mm = container_of(work, struct mm_struct,
1380 void mmput_async(struct mm_struct *mm)
1382 if (atomic_dec_and_test(&mm->mm_users)) {
1383 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1384 schedule_work(&mm->async_put_work);
1387 EXPORT_SYMBOL_GPL(mmput_async);
1391 * set_mm_exe_file - change a reference to the mm's executable file
1392 * @mm: The mm to change.
1393 * @new_exe_file: The new file to use.
1395 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1397 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1398 * invocations: in mmput() nobody alive left, in execve it happens before
1399 * the new mm is made visible to anyone.
1401 * Can only fail if new_exe_file != NULL.
1403 int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1405 struct file *old_exe_file;
1408 * It is safe to dereference the exe_file without RCU as
1409 * this function is only called if nobody else can access
1410 * this mm -- see comment above for justification.
1412 old_exe_file = rcu_dereference_raw(mm->exe_file);
1416 * We expect the caller (i.e., sys_execve) to already denied
1417 * write access, so this is unlikely to fail.
1419 if (unlikely(deny_write_access(new_exe_file)))
1421 get_file(new_exe_file);
1423 rcu_assign_pointer(mm->exe_file, new_exe_file);
1425 allow_write_access(old_exe_file);
1432 * replace_mm_exe_file - replace a reference to the mm's executable file
1433 * @mm: The mm to change.
1434 * @new_exe_file: The new file to use.
1436 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1438 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1440 int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1442 struct vm_area_struct *vma;
1443 struct file *old_exe_file;
1446 /* Forbid mm->exe_file change if old file still mapped. */
1447 old_exe_file = get_mm_exe_file(mm);
1449 VMA_ITERATOR(vmi, mm, 0);
1451 for_each_vma(vmi, vma) {
1454 if (path_equal(&vma->vm_file->f_path,
1455 &old_exe_file->f_path)) {
1460 mmap_read_unlock(mm);
1466 ret = deny_write_access(new_exe_file);
1469 get_file(new_exe_file);
1471 /* set the new file */
1472 mmap_write_lock(mm);
1473 old_exe_file = rcu_dereference_raw(mm->exe_file);
1474 rcu_assign_pointer(mm->exe_file, new_exe_file);
1475 mmap_write_unlock(mm);
1478 allow_write_access(old_exe_file);
1485 * get_mm_exe_file - acquire a reference to the mm's executable file
1486 * @mm: The mm of interest.
1488 * Returns %NULL if mm has no associated executable file.
1489 * User must release file via fput().
1491 struct file *get_mm_exe_file(struct mm_struct *mm)
1493 struct file *exe_file;
1496 exe_file = get_file_rcu(&mm->exe_file);
1502 * get_task_exe_file - acquire a reference to the task's executable file
1505 * Returns %NULL if task's mm (if any) has no associated executable file or
1506 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1507 * User must release file via fput().
1509 struct file *get_task_exe_file(struct task_struct *task)
1511 struct file *exe_file = NULL;
1512 struct mm_struct *mm;
1517 if (!(task->flags & PF_KTHREAD))
1518 exe_file = get_mm_exe_file(mm);
1525 * get_task_mm - acquire a reference to the task's mm
1528 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1529 * this kernel workthread has transiently adopted a user mm with use_mm,
1530 * to do its AIO) is not set and if so returns a reference to it, after
1531 * bumping up the use count. User must release the mm via mmput()
1532 * after use. Typically used by /proc and ptrace.
1534 struct mm_struct *get_task_mm(struct task_struct *task)
1536 struct mm_struct *mm;
1541 if (task->flags & PF_KTHREAD)
1549 EXPORT_SYMBOL_GPL(get_task_mm);
1551 struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1553 struct mm_struct *mm;
1556 err = down_read_killable(&task->signal->exec_update_lock);
1558 return ERR_PTR(err);
1560 mm = get_task_mm(task);
1561 if (mm && mm != current->mm &&
1562 !ptrace_may_access(task, mode)) {
1564 mm = ERR_PTR(-EACCES);
1566 up_read(&task->signal->exec_update_lock);
1571 static void complete_vfork_done(struct task_struct *tsk)
1573 struct completion *vfork;
1576 vfork = tsk->vfork_done;
1577 if (likely(vfork)) {
1578 tsk->vfork_done = NULL;
1584 static int wait_for_vfork_done(struct task_struct *child,
1585 struct completion *vfork)
1587 unsigned int state = TASK_KILLABLE|TASK_FREEZABLE;
1590 cgroup_enter_frozen();
1591 killed = wait_for_completion_state(vfork, state);
1592 cgroup_leave_frozen(false);
1596 child->vfork_done = NULL;
1600 put_task_struct(child);
1604 /* Please note the differences between mmput and mm_release.
1605 * mmput is called whenever we stop holding onto a mm_struct,
1606 * error success whatever.
1608 * mm_release is called after a mm_struct has been removed
1609 * from the current process.
1611 * This difference is important for error handling, when we
1612 * only half set up a mm_struct for a new process and need to restore
1613 * the old one. Because we mmput the new mm_struct before
1614 * restoring the old one. . .
1615 * Eric Biederman 10 January 1998
1617 static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1619 uprobe_free_utask(tsk);
1621 /* Get rid of any cached register state */
1622 deactivate_mm(tsk, mm);
1625 * Signal userspace if we're not exiting with a core dump
1626 * because we want to leave the value intact for debugging
1629 if (tsk->clear_child_tid) {
1630 if (atomic_read(&mm->mm_users) > 1) {
1632 * We don't check the error code - if userspace has
1633 * not set up a proper pointer then tough luck.
1635 put_user(0, tsk->clear_child_tid);
1636 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1637 1, NULL, NULL, 0, 0);
1639 tsk->clear_child_tid = NULL;
1643 * All done, finally we can wake up parent and return this mm to him.
1644 * Also kthread_stop() uses this completion for synchronization.
1646 if (tsk->vfork_done)
1647 complete_vfork_done(tsk);
1650 void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1652 futex_exit_release(tsk);
1653 mm_release(tsk, mm);
1656 void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1658 futex_exec_release(tsk);
1659 mm_release(tsk, mm);
1663 * dup_mm() - duplicates an existing mm structure
1664 * @tsk: the task_struct with which the new mm will be associated.
1665 * @oldmm: the mm to duplicate.
1667 * Allocates a new mm structure and duplicates the provided @oldmm structure
1670 * Return: the duplicated mm or NULL on failure.
1672 static struct mm_struct *dup_mm(struct task_struct *tsk,
1673 struct mm_struct *oldmm)
1675 struct mm_struct *mm;
1682 memcpy(mm, oldmm, sizeof(*mm));
1684 if (!mm_init(mm, tsk, mm->user_ns))
1687 err = dup_mmap(mm, oldmm);
1691 mm->hiwater_rss = get_mm_rss(mm);
1692 mm->hiwater_vm = mm->total_vm;
1694 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1700 /* don't put binfmt in mmput, we haven't got module yet */
1702 mm_init_owner(mm, NULL);
1709 static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1711 struct mm_struct *mm, *oldmm;
1713 tsk->min_flt = tsk->maj_flt = 0;
1714 tsk->nvcsw = tsk->nivcsw = 0;
1715 #ifdef CONFIG_DETECT_HUNG_TASK
1716 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1717 tsk->last_switch_time = 0;
1721 tsk->active_mm = NULL;
1724 * Are we cloning a kernel thread?
1726 * We need to steal a active VM for that..
1728 oldmm = current->mm;
1732 if (clone_flags & CLONE_VM) {
1736 mm = dup_mm(tsk, current->mm);
1742 tsk->active_mm = mm;
1743 sched_mm_cid_fork(tsk);
1747 static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1749 struct fs_struct *fs = current->fs;
1750 if (clone_flags & CLONE_FS) {
1751 /* tsk->fs is already what we want */
1752 spin_lock(&fs->lock);
1753 /* "users" and "in_exec" locked for check_unsafe_exec() */
1755 spin_unlock(&fs->lock);
1759 spin_unlock(&fs->lock);
1762 tsk->fs = copy_fs_struct(fs);
1768 static int copy_files(unsigned long clone_flags, struct task_struct *tsk,
1771 struct files_struct *oldf, *newf;
1775 * A background process may not have any files ...
1777 oldf = current->files;
1786 if (clone_flags & CLONE_FILES) {
1787 atomic_inc(&oldf->count);
1791 newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1801 static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1803 struct sighand_struct *sig;
1805 if (clone_flags & CLONE_SIGHAND) {
1806 refcount_inc(¤t->sighand->count);
1809 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1810 RCU_INIT_POINTER(tsk->sighand, sig);
1814 refcount_set(&sig->count, 1);
1815 spin_lock_irq(¤t->sighand->siglock);
1816 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1817 spin_unlock_irq(¤t->sighand->siglock);
1819 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1820 if (clone_flags & CLONE_CLEAR_SIGHAND)
1821 flush_signal_handlers(tsk, 0);
1826 void __cleanup_sighand(struct sighand_struct *sighand)
1828 if (refcount_dec_and_test(&sighand->count)) {
1829 signalfd_cleanup(sighand);
1831 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1832 * without an RCU grace period, see __lock_task_sighand().
1834 kmem_cache_free(sighand_cachep, sighand);
1839 * Initialize POSIX timer handling for a thread group.
1841 static void posix_cpu_timers_init_group(struct signal_struct *sig)
1843 struct posix_cputimers *pct = &sig->posix_cputimers;
1844 unsigned long cpu_limit;
1846 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1847 posix_cputimers_group_init(pct, cpu_limit);
1850 static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1852 struct signal_struct *sig;
1854 if (clone_flags & CLONE_THREAD)
1857 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1862 sig->nr_threads = 1;
1863 sig->quick_threads = 1;
1864 atomic_set(&sig->live, 1);
1865 refcount_set(&sig->sigcnt, 1);
1867 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1868 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1869 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1871 init_waitqueue_head(&sig->wait_chldexit);
1872 sig->curr_target = tsk;
1873 init_sigpending(&sig->shared_pending);
1874 INIT_HLIST_HEAD(&sig->multiprocess);
1875 seqlock_init(&sig->stats_lock);
1876 prev_cputime_init(&sig->prev_cputime);
1878 #ifdef CONFIG_POSIX_TIMERS
1879 INIT_LIST_HEAD(&sig->posix_timers);
1880 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1881 sig->real_timer.function = it_real_fn;
1884 task_lock(current->group_leader);
1885 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1886 task_unlock(current->group_leader);
1888 posix_cpu_timers_init_group(sig);
1890 tty_audit_fork(sig);
1891 sched_autogroup_fork(sig);
1893 sig->oom_score_adj = current->signal->oom_score_adj;
1894 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1896 mutex_init(&sig->cred_guard_mutex);
1897 init_rwsem(&sig->exec_update_lock);
1902 static void copy_seccomp(struct task_struct *p)
1904 #ifdef CONFIG_SECCOMP
1906 * Must be called with sighand->lock held, which is common to
1907 * all threads in the group. Holding cred_guard_mutex is not
1908 * needed because this new task is not yet running and cannot
1911 assert_spin_locked(¤t->sighand->siglock);
1913 /* Ref-count the new filter user, and assign it. */
1914 get_seccomp_filter(current);
1915 p->seccomp = current->seccomp;
1918 * Explicitly enable no_new_privs here in case it got set
1919 * between the task_struct being duplicated and holding the
1920 * sighand lock. The seccomp state and nnp must be in sync.
1922 if (task_no_new_privs(current))
1923 task_set_no_new_privs(p);
1926 * If the parent gained a seccomp mode after copying thread
1927 * flags and between before we held the sighand lock, we have
1928 * to manually enable the seccomp thread flag here.
1930 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1931 set_task_syscall_work(p, SECCOMP);
1935 SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1937 current->clear_child_tid = tidptr;
1939 return task_pid_vnr(current);
1942 static void rt_mutex_init_task(struct task_struct *p)
1944 raw_spin_lock_init(&p->pi_lock);
1945 #ifdef CONFIG_RT_MUTEXES
1946 p->pi_waiters = RB_ROOT_CACHED;
1947 p->pi_top_task = NULL;
1948 p->pi_blocked_on = NULL;
1952 static inline void init_task_pid_links(struct task_struct *task)
1956 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1957 INIT_HLIST_NODE(&task->pid_links[type]);
1961 init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1963 if (type == PIDTYPE_PID)
1964 task->thread_pid = pid;
1966 task->signal->pids[type] = pid;
1969 static inline void rcu_copy_process(struct task_struct *p)
1971 #ifdef CONFIG_PREEMPT_RCU
1972 p->rcu_read_lock_nesting = 0;
1973 p->rcu_read_unlock_special.s = 0;
1974 p->rcu_blocked_node = NULL;
1975 INIT_LIST_HEAD(&p->rcu_node_entry);
1976 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1977 #ifdef CONFIG_TASKS_RCU
1978 p->rcu_tasks_holdout = false;
1979 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1980 p->rcu_tasks_idle_cpu = -1;
1981 INIT_LIST_HEAD(&p->rcu_tasks_exit_list);
1982 #endif /* #ifdef CONFIG_TASKS_RCU */
1983 #ifdef CONFIG_TASKS_TRACE_RCU
1984 p->trc_reader_nesting = 0;
1985 p->trc_reader_special.s = 0;
1986 INIT_LIST_HEAD(&p->trc_holdout_list);
1987 INIT_LIST_HEAD(&p->trc_blkd_node);
1988 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1992 * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
1993 * @pid: the struct pid for which to create a pidfd
1994 * @flags: flags of the new @pidfd
1995 * @ret: Where to return the file for the pidfd.
1997 * Allocate a new file that stashes @pid and reserve a new pidfd number in the
1998 * caller's file descriptor table. The pidfd is reserved but not installed yet.
2000 * The helper doesn't perform checks on @pid which makes it useful for pidfds
2001 * created via CLONE_PIDFD where @pid has no task attached when the pidfd and
2002 * pidfd file are prepared.
2004 * If this function returns successfully the caller is responsible to either
2005 * call fd_install() passing the returned pidfd and pidfd file as arguments in
2006 * order to install the pidfd into its file descriptor table or they must use
2007 * put_unused_fd() and fput() on the returned pidfd and pidfd file
2010 * This function is useful when a pidfd must already be reserved but there
2011 * might still be points of failure afterwards and the caller wants to ensure
2012 * that no pidfd is leaked into its file descriptor table.
2014 * Return: On success, a reserved pidfd is returned from the function and a new
2015 * pidfd file is returned in the last argument to the function. On
2016 * error, a negative error code is returned from the function and the
2017 * last argument remains unchanged.
2019 static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
2022 struct file *pidfd_file;
2024 pidfd = get_unused_fd_flags(O_CLOEXEC);
2028 pidfd_file = pidfs_alloc_file(pid, flags | O_RDWR);
2029 if (IS_ERR(pidfd_file)) {
2030 put_unused_fd(pidfd);
2031 return PTR_ERR(pidfd_file);
2034 * anon_inode_getfile() ignores everything outside of the
2035 * O_ACCMODE | O_NONBLOCK mask, set PIDFD_THREAD manually.
2037 pidfd_file->f_flags |= (flags & PIDFD_THREAD);
2043 * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2044 * @pid: the struct pid for which to create a pidfd
2045 * @flags: flags of the new @pidfd
2046 * @ret: Where to return the pidfd.
2048 * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2049 * caller's file descriptor table. The pidfd is reserved but not installed yet.
2051 * The helper verifies that @pid is still in use, without PIDFD_THREAD the
2052 * task identified by @pid must be a thread-group leader.
2054 * If this function returns successfully the caller is responsible to either
2055 * call fd_install() passing the returned pidfd and pidfd file as arguments in
2056 * order to install the pidfd into its file descriptor table or they must use
2057 * put_unused_fd() and fput() on the returned pidfd and pidfd file
2060 * This function is useful when a pidfd must already be reserved but there
2061 * might still be points of failure afterwards and the caller wants to ensure
2062 * that no pidfd is leaked into its file descriptor table.
2064 * Return: On success, a reserved pidfd is returned from the function and a new
2065 * pidfd file is returned in the last argument to the function. On
2066 * error, a negative error code is returned from the function and the
2067 * last argument remains unchanged.
2069 int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
2071 bool thread = flags & PIDFD_THREAD;
2073 if (!pid || !pid_has_task(pid, thread ? PIDTYPE_PID : PIDTYPE_TGID))
2076 return __pidfd_prepare(pid, flags, ret);
2079 static void __delayed_free_task(struct rcu_head *rhp)
2081 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
2086 static __always_inline void delayed_free_task(struct task_struct *tsk)
2088 if (IS_ENABLED(CONFIG_MEMCG))
2089 call_rcu(&tsk->rcu, __delayed_free_task);
2094 static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
2096 /* Skip if kernel thread */
2100 /* Skip if spawning a thread or using vfork */
2101 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
2104 /* We need to synchronize with __set_oom_adj */
2105 mutex_lock(&oom_adj_mutex);
2106 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
2107 /* Update the values in case they were changed after copy_signal */
2108 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
2109 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
2110 mutex_unlock(&oom_adj_mutex);
2114 static void rv_task_fork(struct task_struct *p)
2118 for (i = 0; i < RV_PER_TASK_MONITORS; i++)
2119 p->rv[i].da_mon.monitoring = false;
2122 #define rv_task_fork(p) do {} while (0)
2126 * This creates a new process as a copy of the old one,
2127 * but does not actually start it yet.
2129 * It copies the registers, and all the appropriate
2130 * parts of the process environment (as per the clone
2131 * flags). The actual kick-off is left to the caller.
2133 __latent_entropy struct task_struct *copy_process(
2137 struct kernel_clone_args *args)
2139 int pidfd = -1, retval;
2140 struct task_struct *p;
2141 struct multiprocess_signals delayed;
2142 struct file *pidfile = NULL;
2143 const u64 clone_flags = args->flags;
2144 struct nsproxy *nsp = current->nsproxy;
2147 * Don't allow sharing the root directory with processes in a different
2150 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
2151 return ERR_PTR(-EINVAL);
2153 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
2154 return ERR_PTR(-EINVAL);
2157 * Thread groups must share signals as well, and detached threads
2158 * can only be started up within the thread group.
2160 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2161 return ERR_PTR(-EINVAL);
2164 * Shared signal handlers imply shared VM. By way of the above,
2165 * thread groups also imply shared VM. Blocking this case allows
2166 * for various simplifications in other code.
2168 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2169 return ERR_PTR(-EINVAL);
2172 * Siblings of global init remain as zombies on exit since they are
2173 * not reaped by their parent (swapper). To solve this and to avoid
2174 * multi-rooted process trees, prevent global and container-inits
2175 * from creating siblings.
2177 if ((clone_flags & CLONE_PARENT) &&
2178 current->signal->flags & SIGNAL_UNKILLABLE)
2179 return ERR_PTR(-EINVAL);
2182 * If the new process will be in a different pid or user namespace
2183 * do not allow it to share a thread group with the forking task.
2185 if (clone_flags & CLONE_THREAD) {
2186 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2187 (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2188 return ERR_PTR(-EINVAL);
2191 if (clone_flags & CLONE_PIDFD) {
2193 * - CLONE_DETACHED is blocked so that we can potentially
2194 * reuse it later for CLONE_PIDFD.
2196 if (clone_flags & CLONE_DETACHED)
2197 return ERR_PTR(-EINVAL);
2201 * Force any signals received before this point to be delivered
2202 * before the fork happens. Collect up signals sent to multiple
2203 * processes that happen during the fork and delay them so that
2204 * they appear to happen after the fork.
2206 sigemptyset(&delayed.signal);
2207 INIT_HLIST_NODE(&delayed.node);
2209 spin_lock_irq(¤t->sighand->siglock);
2210 if (!(clone_flags & CLONE_THREAD))
2211 hlist_add_head(&delayed.node, ¤t->signal->multiprocess);
2212 recalc_sigpending();
2213 spin_unlock_irq(¤t->sighand->siglock);
2214 retval = -ERESTARTNOINTR;
2215 if (task_sigpending(current))
2219 p = dup_task_struct(current, node);
2222 p->flags &= ~PF_KTHREAD;
2224 p->flags |= PF_KTHREAD;
2225 if (args->user_worker) {
2227 * Mark us a user worker, and block any signal that isn't
2230 p->flags |= PF_USER_WORKER;
2231 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2233 if (args->io_thread)
2234 p->flags |= PF_IO_WORKER;
2237 strscpy_pad(p->comm, args->name, sizeof(p->comm));
2239 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2241 * Clear TID on mm_release()?
2243 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2245 ftrace_graph_init_task(p);
2247 rt_mutex_init_task(p);
2249 lockdep_assert_irqs_enabled();
2250 #ifdef CONFIG_PROVE_LOCKING
2251 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2253 retval = copy_creds(p, clone_flags);
2258 if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2259 if (p->real_cred->user != INIT_USER &&
2260 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2261 goto bad_fork_cleanup_count;
2263 current->flags &= ~PF_NPROC_EXCEEDED;
2266 * If multiple threads are within copy_process(), then this check
2267 * triggers too late. This doesn't hurt, the check is only there
2268 * to stop root fork bombs.
2271 if (data_race(nr_threads >= max_threads))
2272 goto bad_fork_cleanup_count;
2274 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2275 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2276 p->flags |= PF_FORKNOEXEC;
2277 INIT_LIST_HEAD(&p->children);
2278 INIT_LIST_HEAD(&p->sibling);
2279 rcu_copy_process(p);
2280 p->vfork_done = NULL;
2281 spin_lock_init(&p->alloc_lock);
2283 init_sigpending(&p->pending);
2285 p->utime = p->stime = p->gtime = 0;
2286 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2287 p->utimescaled = p->stimescaled = 0;
2289 prev_cputime_init(&p->prev_cputime);
2291 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2292 seqcount_init(&p->vtime.seqcount);
2293 p->vtime.starttime = 0;
2294 p->vtime.state = VTIME_INACTIVE;
2297 #ifdef CONFIG_IO_URING
2301 p->default_timer_slack_ns = current->timer_slack_ns;
2307 task_io_accounting_init(&p->ioac);
2308 acct_clear_integrals(p);
2310 posix_cputimers_init(&p->posix_cputimers);
2312 p->io_context = NULL;
2313 audit_set_context(p, NULL);
2315 if (args->kthread) {
2316 if (!set_kthread_struct(p))
2317 goto bad_fork_cleanup_delayacct;
2320 p->mempolicy = mpol_dup(p->mempolicy);
2321 if (IS_ERR(p->mempolicy)) {
2322 retval = PTR_ERR(p->mempolicy);
2323 p->mempolicy = NULL;
2324 goto bad_fork_cleanup_delayacct;
2327 #ifdef CONFIG_CPUSETS
2328 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2329 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2330 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2332 #ifdef CONFIG_TRACE_IRQFLAGS
2333 memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2334 p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2335 p->irqtrace.softirq_enable_ip = _THIS_IP_;
2336 p->softirqs_enabled = 1;
2337 p->softirq_context = 0;
2340 p->pagefault_disabled = 0;
2342 #ifdef CONFIG_LOCKDEP
2343 lockdep_init_task(p);
2346 #ifdef CONFIG_DEBUG_MUTEXES
2347 p->blocked_on = NULL; /* not blocked yet */
2349 #ifdef CONFIG_BCACHE
2350 p->sequential_io = 0;
2351 p->sequential_io_avg = 0;
2353 #ifdef CONFIG_BPF_SYSCALL
2354 RCU_INIT_POINTER(p->bpf_storage, NULL);
2358 /* Perform scheduler related setup. Assign this task to a CPU. */
2359 retval = sched_fork(clone_flags, p);
2361 goto bad_fork_cleanup_policy;
2363 retval = perf_event_init_task(p, clone_flags);
2365 goto bad_fork_cleanup_policy;
2366 retval = audit_alloc(p);
2368 goto bad_fork_cleanup_perf;
2369 /* copy all the process information */
2371 retval = security_task_alloc(p, clone_flags);
2373 goto bad_fork_cleanup_audit;
2374 retval = copy_semundo(clone_flags, p);
2376 goto bad_fork_cleanup_security;
2377 retval = copy_files(clone_flags, p, args->no_files);
2379 goto bad_fork_cleanup_semundo;
2380 retval = copy_fs(clone_flags, p);
2382 goto bad_fork_cleanup_files;
2383 retval = copy_sighand(clone_flags, p);
2385 goto bad_fork_cleanup_fs;
2386 retval = copy_signal(clone_flags, p);
2388 goto bad_fork_cleanup_sighand;
2389 retval = copy_mm(clone_flags, p);
2391 goto bad_fork_cleanup_signal;
2392 retval = copy_namespaces(clone_flags, p);
2394 goto bad_fork_cleanup_mm;
2395 retval = copy_io(clone_flags, p);
2397 goto bad_fork_cleanup_namespaces;
2398 retval = copy_thread(p, args);
2400 goto bad_fork_cleanup_io;
2402 stackleak_task_init(p);
2404 if (pid != &init_struct_pid) {
2405 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2406 args->set_tid_size);
2408 retval = PTR_ERR(pid);
2409 goto bad_fork_cleanup_thread;
2414 * This has to happen after we've potentially unshared the file
2415 * descriptor table (so that the pidfd doesn't leak into the child
2416 * if the fd table isn't shared).
2418 if (clone_flags & CLONE_PIDFD) {
2419 int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0;
2421 /* Note that no task has been attached to @pid yet. */
2422 retval = __pidfd_prepare(pid, flags, &pidfile);
2424 goto bad_fork_free_pid;
2427 retval = put_user(pidfd, args->pidfd);
2429 goto bad_fork_put_pidfd;
2438 * sigaltstack should be cleared when sharing the same VM
2440 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2444 * Syscall tracing and stepping should be turned off in the
2445 * child regardless of CLONE_PTRACE.
2447 user_disable_single_step(p);
2448 clear_task_syscall_work(p, SYSCALL_TRACE);
2449 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2450 clear_task_syscall_work(p, SYSCALL_EMU);
2452 clear_tsk_latency_tracing(p);
2454 /* ok, now we should be set up.. */
2455 p->pid = pid_nr(pid);
2456 if (clone_flags & CLONE_THREAD) {
2457 p->group_leader = current->group_leader;
2458 p->tgid = current->tgid;
2460 p->group_leader = p;
2465 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2466 p->dirty_paused_when = 0;
2468 p->pdeath_signal = 0;
2469 p->task_works = NULL;
2470 clear_posix_cputimers_work(p);
2472 #ifdef CONFIG_KRETPROBES
2473 p->kretprobe_instances.first = NULL;
2475 #ifdef CONFIG_RETHOOK
2476 p->rethooks.first = NULL;
2480 * Ensure that the cgroup subsystem policies allow the new process to be
2481 * forked. It should be noted that the new process's css_set can be changed
2482 * between here and cgroup_post_fork() if an organisation operation is in
2485 retval = cgroup_can_fork(p, args);
2487 goto bad_fork_put_pidfd;
2490 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2491 * the new task on the correct runqueue. All this *before* the task
2494 * This isn't part of ->can_fork() because while the re-cloning is
2495 * cgroup specific, it unconditionally needs to place the task on a
2498 sched_cgroup_fork(p, args);
2501 * From this point on we must avoid any synchronous user-space
2502 * communication until we take the tasklist-lock. In particular, we do
2503 * not want user-space to be able to predict the process start-time by
2504 * stalling fork(2) after we recorded the start_time but before it is
2505 * visible to the system.
2508 p->start_time = ktime_get_ns();
2509 p->start_boottime = ktime_get_boottime_ns();
2512 * Make it visible to the rest of the system, but dont wake it up yet.
2513 * Need tasklist lock for parent etc handling!
2515 write_lock_irq(&tasklist_lock);
2517 /* CLONE_PARENT re-uses the old parent */
2518 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2519 p->real_parent = current->real_parent;
2520 p->parent_exec_id = current->parent_exec_id;
2521 if (clone_flags & CLONE_THREAD)
2522 p->exit_signal = -1;
2524 p->exit_signal = current->group_leader->exit_signal;
2526 p->real_parent = current;
2527 p->parent_exec_id = current->self_exec_id;
2528 p->exit_signal = args->exit_signal;
2531 klp_copy_process(p);
2535 spin_lock(¤t->sighand->siglock);
2539 rseq_fork(p, clone_flags);
2541 /* Don't start children in a dying pid namespace */
2542 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2544 goto bad_fork_cancel_cgroup;
2547 /* Let kill terminate clone/fork in the middle */
2548 if (fatal_signal_pending(current)) {
2550 goto bad_fork_cancel_cgroup;
2553 /* No more failure paths after this point. */
2556 * Copy seccomp details explicitly here, in case they were changed
2557 * before holding sighand lock.
2561 init_task_pid_links(p);
2562 if (likely(p->pid)) {
2563 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2565 init_task_pid(p, PIDTYPE_PID, pid);
2566 if (thread_group_leader(p)) {
2567 init_task_pid(p, PIDTYPE_TGID, pid);
2568 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2569 init_task_pid(p, PIDTYPE_SID, task_session(current));
2571 if (is_child_reaper(pid)) {
2572 ns_of_pid(pid)->child_reaper = p;
2573 p->signal->flags |= SIGNAL_UNKILLABLE;
2575 p->signal->shared_pending.signal = delayed.signal;
2576 p->signal->tty = tty_kref_get(current->signal->tty);
2578 * Inherit has_child_subreaper flag under the same
2579 * tasklist_lock with adding child to the process tree
2580 * for propagate_has_child_subreaper optimization.
2582 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2583 p->real_parent->signal->is_child_subreaper;
2584 list_add_tail(&p->sibling, &p->real_parent->children);
2585 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2586 attach_pid(p, PIDTYPE_TGID);
2587 attach_pid(p, PIDTYPE_PGID);
2588 attach_pid(p, PIDTYPE_SID);
2589 __this_cpu_inc(process_counts);
2591 current->signal->nr_threads++;
2592 current->signal->quick_threads++;
2593 atomic_inc(¤t->signal->live);
2594 refcount_inc(¤t->signal->sigcnt);
2595 task_join_group_stop(p);
2596 list_add_tail_rcu(&p->thread_node,
2597 &p->signal->thread_head);
2599 attach_pid(p, PIDTYPE_PID);
2603 hlist_del_init(&delayed.node);
2604 spin_unlock(¤t->sighand->siglock);
2605 syscall_tracepoint_update(p);
2606 write_unlock_irq(&tasklist_lock);
2609 fd_install(pidfd, pidfile);
2611 proc_fork_connector(p);
2613 cgroup_post_fork(p, args);
2616 trace_task_newtask(p, clone_flags);
2617 uprobe_copy_process(p, clone_flags);
2618 user_events_fork(p, clone_flags);
2620 copy_oom_score_adj(clone_flags, p);
2624 bad_fork_cancel_cgroup:
2626 spin_unlock(¤t->sighand->siglock);
2627 write_unlock_irq(&tasklist_lock);
2628 cgroup_cancel_fork(p, args);
2630 if (clone_flags & CLONE_PIDFD) {
2632 put_unused_fd(pidfd);
2635 if (pid != &init_struct_pid)
2637 bad_fork_cleanup_thread:
2639 bad_fork_cleanup_io:
2642 bad_fork_cleanup_namespaces:
2643 exit_task_namespaces(p);
2644 bad_fork_cleanup_mm:
2646 mm_clear_owner(p->mm, p);
2649 bad_fork_cleanup_signal:
2650 if (!(clone_flags & CLONE_THREAD))
2651 free_signal_struct(p->signal);
2652 bad_fork_cleanup_sighand:
2653 __cleanup_sighand(p->sighand);
2654 bad_fork_cleanup_fs:
2655 exit_fs(p); /* blocking */
2656 bad_fork_cleanup_files:
2657 exit_files(p); /* blocking */
2658 bad_fork_cleanup_semundo:
2660 bad_fork_cleanup_security:
2661 security_task_free(p);
2662 bad_fork_cleanup_audit:
2664 bad_fork_cleanup_perf:
2665 perf_event_free_task(p);
2666 bad_fork_cleanup_policy:
2667 lockdep_free_task(p);
2669 mpol_put(p->mempolicy);
2671 bad_fork_cleanup_delayacct:
2672 delayacct_tsk_free(p);
2673 bad_fork_cleanup_count:
2674 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2677 WRITE_ONCE(p->__state, TASK_DEAD);
2678 exit_task_stack_account(p);
2680 delayed_free_task(p);
2682 spin_lock_irq(¤t->sighand->siglock);
2683 hlist_del_init(&delayed.node);
2684 spin_unlock_irq(¤t->sighand->siglock);
2685 return ERR_PTR(retval);
2688 static inline void init_idle_pids(struct task_struct *idle)
2692 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2693 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2694 init_task_pid(idle, type, &init_struct_pid);
2698 static int idle_dummy(void *dummy)
2700 /* This function is never called */
2704 struct task_struct * __init fork_idle(int cpu)
2706 struct task_struct *task;
2707 struct kernel_clone_args args = {
2715 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2716 if (!IS_ERR(task)) {
2717 init_idle_pids(task);
2718 init_idle(task, cpu);
2725 * This is like kernel_clone(), but shaved down and tailored to just
2726 * creating io_uring workers. It returns a created task, or an error pointer.
2727 * The returned task is inactive, and the caller must fire it up through
2728 * wake_up_new_task(p). All signals are blocked in the created task.
2730 struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2732 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2734 struct kernel_clone_args args = {
2735 .flags = ((lower_32_bits(flags) | CLONE_VM |
2736 CLONE_UNTRACED) & ~CSIGNAL),
2737 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2744 return copy_process(NULL, 0, node, &args);
2748 * Ok, this is the main fork-routine.
2750 * It copies the process, and if successful kick-starts
2751 * it and waits for it to finish using the VM if required.
2753 * args->exit_signal is expected to be checked for sanity by the caller.
2755 pid_t kernel_clone(struct kernel_clone_args *args)
2757 u64 clone_flags = args->flags;
2758 struct completion vfork;
2760 struct task_struct *p;
2765 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2766 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2767 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2768 * field in struct clone_args and it still doesn't make sense to have
2769 * them both point at the same memory location. Performing this check
2770 * here has the advantage that we don't need to have a separate helper
2771 * to check for legacy clone().
2773 if ((clone_flags & CLONE_PIDFD) &&
2774 (clone_flags & CLONE_PARENT_SETTID) &&
2775 (args->pidfd == args->parent_tid))
2779 * Determine whether and which event to report to ptracer. When
2780 * called from kernel_thread or CLONE_UNTRACED is explicitly
2781 * requested, no event is reported; otherwise, report if the event
2782 * for the type of forking is enabled.
2784 if (!(clone_flags & CLONE_UNTRACED)) {
2785 if (clone_flags & CLONE_VFORK)
2786 trace = PTRACE_EVENT_VFORK;
2787 else if (args->exit_signal != SIGCHLD)
2788 trace = PTRACE_EVENT_CLONE;
2790 trace = PTRACE_EVENT_FORK;
2792 if (likely(!ptrace_event_enabled(current, trace)))
2796 p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2797 add_latent_entropy();
2803 * Do this prior waking up the new thread - the thread pointer
2804 * might get invalid after that point, if the thread exits quickly.
2806 trace_sched_process_fork(current, p);
2808 pid = get_task_pid(p, PIDTYPE_PID);
2811 if (clone_flags & CLONE_PARENT_SETTID)
2812 put_user(nr, args->parent_tid);
2814 if (clone_flags & CLONE_VFORK) {
2815 p->vfork_done = &vfork;
2816 init_completion(&vfork);
2820 if (IS_ENABLED(CONFIG_LRU_GEN_WALKS_MMU) && !(clone_flags & CLONE_VM)) {
2821 /* lock the task to synchronize with memcg migration */
2823 lru_gen_add_mm(p->mm);
2827 wake_up_new_task(p);
2829 /* forking complete and child started to run, tell ptracer */
2830 if (unlikely(trace))
2831 ptrace_event_pid(trace, pid);
2833 if (clone_flags & CLONE_VFORK) {
2834 if (!wait_for_vfork_done(p, &vfork))
2835 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2843 * Create a kernel thread.
2845 pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
2846 unsigned long flags)
2848 struct kernel_clone_args args = {
2849 .flags = ((lower_32_bits(flags) | CLONE_VM |
2850 CLONE_UNTRACED) & ~CSIGNAL),
2851 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2858 return kernel_clone(&args);
2862 * Create a user mode thread.
2864 pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
2866 struct kernel_clone_args args = {
2867 .flags = ((lower_32_bits(flags) | CLONE_VM |
2868 CLONE_UNTRACED) & ~CSIGNAL),
2869 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2874 return kernel_clone(&args);
2877 #ifdef __ARCH_WANT_SYS_FORK
2878 SYSCALL_DEFINE0(fork)
2881 struct kernel_clone_args args = {
2882 .exit_signal = SIGCHLD,
2885 return kernel_clone(&args);
2887 /* can not support in nommu mode */
2893 #ifdef __ARCH_WANT_SYS_VFORK
2894 SYSCALL_DEFINE0(vfork)
2896 struct kernel_clone_args args = {
2897 .flags = CLONE_VFORK | CLONE_VM,
2898 .exit_signal = SIGCHLD,
2901 return kernel_clone(&args);
2905 #ifdef __ARCH_WANT_SYS_CLONE
2906 #ifdef CONFIG_CLONE_BACKWARDS
2907 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2908 int __user *, parent_tidptr,
2910 int __user *, child_tidptr)
2911 #elif defined(CONFIG_CLONE_BACKWARDS2)
2912 SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2913 int __user *, parent_tidptr,
2914 int __user *, child_tidptr,
2916 #elif defined(CONFIG_CLONE_BACKWARDS3)
2917 SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2919 int __user *, parent_tidptr,
2920 int __user *, child_tidptr,
2923 SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2924 int __user *, parent_tidptr,
2925 int __user *, child_tidptr,
2929 struct kernel_clone_args args = {
2930 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2931 .pidfd = parent_tidptr,
2932 .child_tid = child_tidptr,
2933 .parent_tid = parent_tidptr,
2934 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2939 return kernel_clone(&args);
2943 #ifdef __ARCH_WANT_SYS_CLONE3
2945 noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2946 struct clone_args __user *uargs,
2950 struct clone_args args;
2951 pid_t *kset_tid = kargs->set_tid;
2953 BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2954 CLONE_ARGS_SIZE_VER0);
2955 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2956 CLONE_ARGS_SIZE_VER1);
2957 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2958 CLONE_ARGS_SIZE_VER2);
2959 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2961 if (unlikely(usize > PAGE_SIZE))
2963 if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2966 err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2970 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2973 if (unlikely(!args.set_tid && args.set_tid_size > 0))
2976 if (unlikely(args.set_tid && args.set_tid_size == 0))
2980 * Verify that higher 32bits of exit_signal are unset and that
2981 * it is a valid signal
2983 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2984 !valid_signal(args.exit_signal)))
2987 if ((args.flags & CLONE_INTO_CGROUP) &&
2988 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2991 *kargs = (struct kernel_clone_args){
2992 .flags = args.flags,
2993 .pidfd = u64_to_user_ptr(args.pidfd),
2994 .child_tid = u64_to_user_ptr(args.child_tid),
2995 .parent_tid = u64_to_user_ptr(args.parent_tid),
2996 .exit_signal = args.exit_signal,
2997 .stack = args.stack,
2998 .stack_size = args.stack_size,
3000 .set_tid_size = args.set_tid_size,
3001 .cgroup = args.cgroup,
3005 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
3006 (kargs->set_tid_size * sizeof(pid_t))))
3009 kargs->set_tid = kset_tid;
3015 * clone3_stack_valid - check and prepare stack
3016 * @kargs: kernel clone args
3018 * Verify that the stack arguments userspace gave us are sane.
3019 * In addition, set the stack direction for userspace since it's easy for us to
3022 static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
3024 if (kargs->stack == 0) {
3025 if (kargs->stack_size > 0)
3028 if (kargs->stack_size == 0)
3031 if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
3034 #if !defined(CONFIG_STACK_GROWSUP)
3035 kargs->stack += kargs->stack_size;
3042 static bool clone3_args_valid(struct kernel_clone_args *kargs)
3044 /* Verify that no unknown flags are passed along. */
3046 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
3050 * - make the CLONE_DETACHED bit reusable for clone3
3051 * - make the CSIGNAL bits reusable for clone3
3053 if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
3056 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
3057 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
3060 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
3064 if (!clone3_stack_valid(kargs))
3071 * sys_clone3 - create a new process with specific properties
3072 * @uargs: argument structure
3073 * @size: size of @uargs
3075 * clone3() is the extensible successor to clone()/clone2().
3076 * It takes a struct as argument that is versioned by its size.
3078 * Return: On success, a positive PID for the child process.
3079 * On error, a negative errno number.
3081 SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
3085 struct kernel_clone_args kargs;
3086 pid_t set_tid[MAX_PID_NS_LEVEL];
3088 kargs.set_tid = set_tid;
3090 err = copy_clone_args_from_user(&kargs, uargs, size);
3094 if (!clone3_args_valid(&kargs))
3097 return kernel_clone(&kargs);
3101 void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
3103 struct task_struct *leader, *parent, *child;
3106 read_lock(&tasklist_lock);
3107 leader = top = top->group_leader;
3109 for_each_thread(leader, parent) {
3110 list_for_each_entry(child, &parent->children, sibling) {
3111 res = visitor(child, data);
3123 if (leader != top) {
3125 parent = child->real_parent;
3126 leader = parent->group_leader;
3130 read_unlock(&tasklist_lock);
3133 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
3134 #define ARCH_MIN_MMSTRUCT_ALIGN 0
3137 static void sighand_ctor(void *data)
3139 struct sighand_struct *sighand = data;
3141 spin_lock_init(&sighand->siglock);
3142 init_waitqueue_head(&sighand->signalfd_wqh);
3145 void __init mm_cache_init(void)
3147 unsigned int mm_size;
3150 * The mm_cpumask is located at the end of mm_struct, and is
3151 * dynamically sized based on the maximum CPU number this system
3152 * can have, taking hotplug into account (nr_cpu_ids).
3154 mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size();
3156 mm_cachep = kmem_cache_create_usercopy("mm_struct",
3157 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
3158 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3159 offsetof(struct mm_struct, saved_auxv),
3160 sizeof_field(struct mm_struct, saved_auxv),
3164 void __init proc_caches_init(void)
3166 sighand_cachep = kmem_cache_create("sighand_cache",
3167 sizeof(struct sighand_struct), 0,
3168 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
3169 SLAB_ACCOUNT, sighand_ctor);
3170 signal_cachep = kmem_cache_create("signal_cache",
3171 sizeof(struct signal_struct), 0,
3172 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3174 files_cachep = kmem_cache_create("files_cache",
3175 sizeof(struct files_struct), 0,
3176 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3178 fs_cachep = kmem_cache_create("fs_cache",
3179 sizeof(struct fs_struct), 0,
3180 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3183 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
3184 #ifdef CONFIG_PER_VMA_LOCK
3185 vma_lock_cachep = KMEM_CACHE(vma_lock, SLAB_PANIC|SLAB_ACCOUNT);
3188 nsproxy_cache_init();
3192 * Check constraints on flags passed to the unshare system call.
3194 static int check_unshare_flags(unsigned long unshare_flags)
3196 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3197 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3198 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3199 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3203 * Not implemented, but pretend it works if there is nothing
3204 * to unshare. Note that unsharing the address space or the
3205 * signal handlers also need to unshare the signal queues (aka
3208 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3209 if (!thread_group_empty(current))
3212 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3213 if (refcount_read(¤t->sighand->count) > 1)
3216 if (unshare_flags & CLONE_VM) {
3217 if (!current_is_single_threaded())
3225 * Unshare the filesystem structure if it is being shared
3227 static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3229 struct fs_struct *fs = current->fs;
3231 if (!(unshare_flags & CLONE_FS) || !fs)
3234 /* don't need lock here; in the worst case we'll do useless copy */
3238 *new_fsp = copy_fs_struct(fs);
3246 * Unshare file descriptor table if it is being shared
3248 int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3249 struct files_struct **new_fdp)
3251 struct files_struct *fd = current->files;
3254 if ((unshare_flags & CLONE_FILES) &&
3255 (fd && atomic_read(&fd->count) > 1)) {
3256 *new_fdp = dup_fd(fd, max_fds, &error);
3265 * unshare allows a process to 'unshare' part of the process
3266 * context which was originally shared using clone. copy_*
3267 * functions used by kernel_clone() cannot be used here directly
3268 * because they modify an inactive task_struct that is being
3269 * constructed. Here we are modifying the current, active,
3272 int ksys_unshare(unsigned long unshare_flags)
3274 struct fs_struct *fs, *new_fs = NULL;
3275 struct files_struct *new_fd = NULL;
3276 struct cred *new_cred = NULL;
3277 struct nsproxy *new_nsproxy = NULL;
3282 * If unsharing a user namespace must also unshare the thread group
3283 * and unshare the filesystem root and working directories.
3285 if (unshare_flags & CLONE_NEWUSER)
3286 unshare_flags |= CLONE_THREAD | CLONE_FS;
3288 * If unsharing vm, must also unshare signal handlers.
3290 if (unshare_flags & CLONE_VM)
3291 unshare_flags |= CLONE_SIGHAND;
3293 * If unsharing a signal handlers, must also unshare the signal queues.
3295 if (unshare_flags & CLONE_SIGHAND)
3296 unshare_flags |= CLONE_THREAD;
3298 * If unsharing namespace, must also unshare filesystem information.
3300 if (unshare_flags & CLONE_NEWNS)
3301 unshare_flags |= CLONE_FS;
3303 err = check_unshare_flags(unshare_flags);
3305 goto bad_unshare_out;
3307 * CLONE_NEWIPC must also detach from the undolist: after switching
3308 * to a new ipc namespace, the semaphore arrays from the old
3309 * namespace are unreachable.
3311 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3313 err = unshare_fs(unshare_flags, &new_fs);
3315 goto bad_unshare_out;
3316 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3318 goto bad_unshare_cleanup_fs;
3319 err = unshare_userns(unshare_flags, &new_cred);
3321 goto bad_unshare_cleanup_fd;
3322 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3325 goto bad_unshare_cleanup_cred;
3328 err = set_cred_ucounts(new_cred);
3330 goto bad_unshare_cleanup_cred;
3333 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3336 * CLONE_SYSVSEM is equivalent to sys_exit().
3340 if (unshare_flags & CLONE_NEWIPC) {
3341 /* Orphan segments in old ns (see sem above). */
3343 shm_init_task(current);
3347 switch_task_namespaces(current, new_nsproxy);
3353 spin_lock(&fs->lock);
3354 current->fs = new_fs;
3359 spin_unlock(&fs->lock);
3363 swap(current->files, new_fd);
3365 task_unlock(current);
3368 /* Install the new user namespace */
3369 commit_creds(new_cred);
3374 perf_event_namespaces(current);
3376 bad_unshare_cleanup_cred:
3379 bad_unshare_cleanup_fd:
3381 put_files_struct(new_fd);
3383 bad_unshare_cleanup_fs:
3385 free_fs_struct(new_fs);
3391 SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3393 return ksys_unshare(unshare_flags);
3397 * Helper to unshare the files of the current task.
3398 * We don't want to expose copy_files internals to
3399 * the exec layer of the kernel.
3402 int unshare_files(void)
3404 struct task_struct *task = current;
3405 struct files_struct *old, *copy = NULL;
3408 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, ©);
3416 put_files_struct(old);
3420 int sysctl_max_threads(struct ctl_table *table, int write,
3421 void *buffer, size_t *lenp, loff_t *ppos)
3425 int threads = max_threads;
3427 int max = MAX_THREADS;
3434 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3438 max_threads = threads;