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>
100 #include <asm/pgalloc.h>
101 #include <linux/uaccess.h>
102 #include <asm/mmu_context.h>
103 #include <asm/cacheflush.h>
104 #include <asm/tlbflush.h>
106 #include <trace/events/sched.h>
108 #define CREATE_TRACE_POINTS
109 #include <trace/events/task.h>
112 * Minimum number of threads to boot the kernel
114 #define MIN_THREADS 20
117 * Maximum number of threads
119 #define MAX_THREADS FUTEX_TID_MASK
122 * Protected counters by write_lock_irq(&tasklist_lock)
124 unsigned long total_forks
; /* Handle normal Linux uptimes. */
125 int nr_threads
; /* The idle threads do not count.. */
127 static int max_threads
; /* tunable limit on nr_threads */
129 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
131 static const char * const resident_page_types
[] = {
132 NAMED_ARRAY_INDEX(MM_FILEPAGES
),
133 NAMED_ARRAY_INDEX(MM_ANONPAGES
),
134 NAMED_ARRAY_INDEX(MM_SWAPENTS
),
135 NAMED_ARRAY_INDEX(MM_SHMEMPAGES
),
138 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
140 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
142 #ifdef CONFIG_PROVE_RCU
143 int lockdep_tasklist_lock_is_held(void)
145 return lockdep_is_held(&tasklist_lock
);
147 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
148 #endif /* #ifdef CONFIG_PROVE_RCU */
150 int nr_processes(void)
155 for_each_possible_cpu(cpu
)
156 total
+= per_cpu(process_counts
, cpu
);
161 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
165 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
166 static struct kmem_cache
*task_struct_cachep
;
168 static inline struct task_struct
*alloc_task_struct_node(int node
)
170 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
173 static inline void free_task_struct(struct task_struct
*tsk
)
175 kmem_cache_free(task_struct_cachep
, tsk
);
179 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
182 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
183 * kmemcache based allocator.
185 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
187 #ifdef CONFIG_VMAP_STACK
189 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
190 * flush. Try to minimize the number of calls by caching stacks.
192 #define NR_CACHED_STACKS 2
193 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
195 static int free_vm_stack_cache(unsigned int cpu
)
197 struct vm_struct
**cached_vm_stacks
= per_cpu_ptr(cached_stacks
, cpu
);
200 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
201 struct vm_struct
*vm_stack
= cached_vm_stacks
[i
];
206 vfree(vm_stack
->addr
);
207 cached_vm_stacks
[i
] = NULL
;
214 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
216 #ifdef CONFIG_VMAP_STACK
220 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
223 s
= this_cpu_xchg(cached_stacks
[i
], NULL
);
228 /* Mark stack accessible for KASAN. */
229 kasan_unpoison_range(s
->addr
, THREAD_SIZE
);
231 /* Clear stale pointers from reused stack. */
232 memset(s
->addr
, 0, THREAD_SIZE
);
234 tsk
->stack_vm_area
= s
;
235 tsk
->stack
= s
->addr
;
240 * Allocated stacks are cached and later reused by new threads,
241 * so memcg accounting is performed manually on assigning/releasing
242 * stacks to tasks. Drop __GFP_ACCOUNT.
244 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_ALIGN
,
245 VMALLOC_START
, VMALLOC_END
,
246 THREADINFO_GFP
& ~__GFP_ACCOUNT
,
248 0, node
, __builtin_return_address(0));
251 * We can't call find_vm_area() in interrupt context, and
252 * free_thread_stack() can be called in interrupt context,
253 * so cache the vm_struct.
256 tsk
->stack_vm_area
= find_vm_area(stack
);
261 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
265 tsk
->stack
= kasan_reset_tag(page_address(page
));
272 static inline void free_thread_stack(struct task_struct
*tsk
)
274 #ifdef CONFIG_VMAP_STACK
275 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
280 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
281 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
283 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
284 if (this_cpu_cmpxchg(cached_stacks
[i
],
285 NULL
, tsk
->stack_vm_area
) != NULL
)
291 vfree_atomic(tsk
->stack
);
296 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
299 static struct kmem_cache
*thread_stack_cache
;
301 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
304 unsigned long *stack
;
305 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
306 stack
= kasan_reset_tag(stack
);
311 static void free_thread_stack(struct task_struct
*tsk
)
313 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
316 void thread_stack_cache_init(void)
318 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
319 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
321 BUG_ON(thread_stack_cache
== NULL
);
326 /* SLAB cache for signal_struct structures (tsk->signal) */
327 static struct kmem_cache
*signal_cachep
;
329 /* SLAB cache for sighand_struct structures (tsk->sighand) */
330 struct kmem_cache
*sighand_cachep
;
332 /* SLAB cache for files_struct structures (tsk->files) */
333 struct kmem_cache
*files_cachep
;
335 /* SLAB cache for fs_struct structures (tsk->fs) */
336 struct kmem_cache
*fs_cachep
;
338 /* SLAB cache for vm_area_struct structures */
339 static struct kmem_cache
*vm_area_cachep
;
341 /* SLAB cache for mm_struct structures (tsk->mm) */
342 static struct kmem_cache
*mm_cachep
;
344 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
346 struct vm_area_struct
*vma
;
348 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
354 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
356 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
359 ASSERT_EXCLUSIVE_WRITER(orig
->vm_flags
);
360 ASSERT_EXCLUSIVE_WRITER(orig
->vm_file
);
362 * orig->shared.rb may be modified concurrently, but the clone
363 * will be reinitialized.
365 *new = data_race(*orig
);
366 INIT_LIST_HEAD(&new->anon_vma_chain
);
367 new->vm_next
= new->vm_prev
= NULL
;
372 void vm_area_free(struct vm_area_struct
*vma
)
374 kmem_cache_free(vm_area_cachep
, vma
);
377 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
379 void *stack
= task_stack_page(tsk
);
380 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
383 /* All stack pages are in the same node. */
385 mod_lruvec_page_state(vm
->pages
[0], NR_KERNEL_STACK_KB
,
386 account
* (THREAD_SIZE
/ 1024));
388 mod_lruvec_kmem_state(stack
, NR_KERNEL_STACK_KB
,
389 account
* (THREAD_SIZE
/ 1024));
392 static int memcg_charge_kernel_stack(struct task_struct
*tsk
)
394 #ifdef CONFIG_VMAP_STACK
395 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
398 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
403 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
405 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
407 * If memcg_kmem_charge_page() fails, page's
408 * memory cgroup pointer is NULL, and
409 * memcg_kmem_uncharge_page() in free_thread_stack()
410 * will ignore this page.
412 ret
= memcg_kmem_charge_page(vm
->pages
[i
], GFP_KERNEL
,
422 static void release_task_stack(struct task_struct
*tsk
)
424 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
425 return; /* Better to leak the stack than to free prematurely */
427 account_kernel_stack(tsk
, -1);
428 free_thread_stack(tsk
);
430 #ifdef CONFIG_VMAP_STACK
431 tsk
->stack_vm_area
= NULL
;
435 #ifdef CONFIG_THREAD_INFO_IN_TASK
436 void put_task_stack(struct task_struct
*tsk
)
438 if (refcount_dec_and_test(&tsk
->stack_refcount
))
439 release_task_stack(tsk
);
443 void free_task(struct task_struct
*tsk
)
447 #ifndef CONFIG_THREAD_INFO_IN_TASK
449 * The task is finally done with both the stack and thread_info,
452 release_task_stack(tsk
);
455 * If the task had a separate stack allocation, it should be gone
458 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
460 rt_mutex_debug_task_free(tsk
);
461 ftrace_graph_exit_task(tsk
);
462 arch_release_task_struct(tsk
);
463 if (tsk
->flags
& PF_KTHREAD
)
464 free_kthread_struct(tsk
);
465 free_task_struct(tsk
);
467 EXPORT_SYMBOL(free_task
);
470 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
471 struct mm_struct
*oldmm
)
473 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
474 struct rb_node
**rb_link
, *rb_parent
;
476 unsigned long charge
;
479 uprobe_start_dup_mmap();
480 if (mmap_write_lock_killable(oldmm
)) {
482 goto fail_uprobe_end
;
484 flush_cache_dup_mm(oldmm
);
485 uprobe_dup_mmap(oldmm
, mm
);
487 * Not linked in yet - no deadlock potential:
489 mmap_write_lock_nested(mm
, SINGLE_DEPTH_NESTING
);
491 /* No ordering required: file already has been exposed. */
492 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
494 mm
->total_vm
= oldmm
->total_vm
;
495 mm
->data_vm
= oldmm
->data_vm
;
496 mm
->exec_vm
= oldmm
->exec_vm
;
497 mm
->stack_vm
= oldmm
->stack_vm
;
499 rb_link
= &mm
->mm_rb
.rb_node
;
502 retval
= ksm_fork(mm
, oldmm
);
505 retval
= khugepaged_fork(mm
, oldmm
);
510 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
513 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
514 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
519 * Don't duplicate many vmas if we've been oom-killed (for
522 if (fatal_signal_pending(current
)) {
526 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
527 unsigned long len
= vma_pages(mpnt
);
529 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
533 tmp
= vm_area_dup(mpnt
);
536 retval
= vma_dup_policy(mpnt
, tmp
);
538 goto fail_nomem_policy
;
540 retval
= dup_userfaultfd(tmp
, &uf
);
542 goto fail_nomem_anon_vma_fork
;
543 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
545 * VM_WIPEONFORK gets a clean slate in the child.
546 * Don't prepare anon_vma until fault since we don't
547 * copy page for current vma.
549 tmp
->anon_vma
= NULL
;
550 } else if (anon_vma_fork(tmp
, mpnt
))
551 goto fail_nomem_anon_vma_fork
;
552 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
555 struct inode
*inode
= file_inode(file
);
556 struct address_space
*mapping
= file
->f_mapping
;
559 if (tmp
->vm_flags
& VM_DENYWRITE
)
560 put_write_access(inode
);
561 i_mmap_lock_write(mapping
);
562 if (tmp
->vm_flags
& VM_SHARED
)
563 mapping_allow_writable(mapping
);
564 flush_dcache_mmap_lock(mapping
);
565 /* insert tmp into the share list, just after mpnt */
566 vma_interval_tree_insert_after(tmp
, mpnt
,
568 flush_dcache_mmap_unlock(mapping
);
569 i_mmap_unlock_write(mapping
);
573 * Clear hugetlb-related page reserves for children. This only
574 * affects MAP_PRIVATE mappings. Faults generated by the child
575 * are not guaranteed to succeed, even if read-only
577 if (is_vm_hugetlb_page(tmp
))
578 reset_vma_resv_huge_pages(tmp
);
581 * Link in the new vma and copy the page table entries.
584 pprev
= &tmp
->vm_next
;
588 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
589 rb_link
= &tmp
->vm_rb
.rb_right
;
590 rb_parent
= &tmp
->vm_rb
;
593 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
594 retval
= copy_page_range(tmp
, mpnt
);
596 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
597 tmp
->vm_ops
->open(tmp
);
602 /* a new mm has just been created */
603 retval
= arch_dup_mmap(oldmm
, mm
);
605 mmap_write_unlock(mm
);
607 mmap_write_unlock(oldmm
);
608 dup_userfaultfd_complete(&uf
);
610 uprobe_end_dup_mmap();
612 fail_nomem_anon_vma_fork
:
613 mpol_put(vma_policy(tmp
));
618 vm_unacct_memory(charge
);
622 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
624 mm
->pgd
= pgd_alloc(mm
);
625 if (unlikely(!mm
->pgd
))
630 static inline void mm_free_pgd(struct mm_struct
*mm
)
632 pgd_free(mm
, mm
->pgd
);
635 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
637 mmap_write_lock(oldmm
);
638 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
639 mmap_write_unlock(oldmm
);
642 #define mm_alloc_pgd(mm) (0)
643 #define mm_free_pgd(mm)
644 #endif /* CONFIG_MMU */
646 static void check_mm(struct mm_struct
*mm
)
650 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types
) != NR_MM_COUNTERS
,
651 "Please make sure 'struct resident_page_types[]' is updated as well");
653 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
654 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
657 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
658 mm
, resident_page_types
[i
], x
);
661 if (mm_pgtables_bytes(mm
))
662 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
663 mm_pgtables_bytes(mm
));
665 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
666 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
670 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
671 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
674 * Called when the last reference to the mm
675 * is dropped: either by a lazy thread or by
676 * mmput. Free the page directory and the mm.
678 void __mmdrop(struct mm_struct
*mm
)
680 BUG_ON(mm
== &init_mm
);
681 WARN_ON_ONCE(mm
== current
->mm
);
682 WARN_ON_ONCE(mm
== current
->active_mm
);
685 mmu_notifier_subscriptions_destroy(mm
);
687 put_user_ns(mm
->user_ns
);
690 EXPORT_SYMBOL_GPL(__mmdrop
);
692 static void mmdrop_async_fn(struct work_struct
*work
)
694 struct mm_struct
*mm
;
696 mm
= container_of(work
, struct mm_struct
, async_put_work
);
700 static void mmdrop_async(struct mm_struct
*mm
)
702 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
703 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
704 schedule_work(&mm
->async_put_work
);
708 static inline void free_signal_struct(struct signal_struct
*sig
)
710 taskstats_tgid_free(sig
);
711 sched_autogroup_exit(sig
);
713 * __mmdrop is not safe to call from softirq context on x86 due to
714 * pgd_dtor so postpone it to the async context
717 mmdrop_async(sig
->oom_mm
);
718 kmem_cache_free(signal_cachep
, sig
);
721 static inline void put_signal_struct(struct signal_struct
*sig
)
723 if (refcount_dec_and_test(&sig
->sigcnt
))
724 free_signal_struct(sig
);
727 void __put_task_struct(struct task_struct
*tsk
)
729 WARN_ON(!tsk
->exit_state
);
730 WARN_ON(refcount_read(&tsk
->usage
));
731 WARN_ON(tsk
== current
);
735 task_numa_free(tsk
, true);
736 security_task_free(tsk
);
738 delayacct_tsk_free(tsk
);
739 put_signal_struct(tsk
->signal
);
741 if (!profile_handoff_task(tsk
))
744 EXPORT_SYMBOL_GPL(__put_task_struct
);
746 void __init __weak
arch_task_cache_init(void) { }
751 static void set_max_threads(unsigned int max_threads_suggested
)
754 unsigned long nr_pages
= totalram_pages();
757 * The number of threads shall be limited such that the thread
758 * structures may only consume a small part of the available memory.
760 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
761 threads
= MAX_THREADS
;
763 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
764 (u64
) THREAD_SIZE
* 8UL);
766 if (threads
> max_threads_suggested
)
767 threads
= max_threads_suggested
;
769 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
772 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
773 /* Initialized by the architecture: */
774 int arch_task_struct_size __read_mostly
;
777 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
778 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
780 /* Fetch thread_struct whitelist for the architecture. */
781 arch_thread_struct_whitelist(offset
, size
);
784 * Handle zero-sized whitelist or empty thread_struct, otherwise
785 * adjust offset to position of thread_struct in task_struct.
787 if (unlikely(*size
== 0))
790 *offset
+= offsetof(struct task_struct
, thread
);
792 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
794 void __init
fork_init(void)
797 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
798 #ifndef ARCH_MIN_TASKALIGN
799 #define ARCH_MIN_TASKALIGN 0
801 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
802 unsigned long useroffset
, usersize
;
804 /* create a slab on which task_structs can be allocated */
805 task_struct_whitelist(&useroffset
, &usersize
);
806 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
807 arch_task_struct_size
, align
,
808 SLAB_PANIC
|SLAB_ACCOUNT
,
809 useroffset
, usersize
, NULL
);
812 /* do the arch specific task caches init */
813 arch_task_cache_init();
815 set_max_threads(MAX_THREADS
);
817 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
818 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
819 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
820 init_task
.signal
->rlim
[RLIMIT_NPROC
];
822 for (i
= 0; i
< UCOUNT_COUNTS
; i
++)
823 init_user_ns
.ucount_max
[i
] = max_threads
/2;
825 #ifdef CONFIG_VMAP_STACK
826 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
827 NULL
, free_vm_stack_cache
);
832 lockdep_init_task(&init_task
);
836 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
837 struct task_struct
*src
)
843 void set_task_stack_end_magic(struct task_struct
*tsk
)
845 unsigned long *stackend
;
847 stackend
= end_of_stack(tsk
);
848 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
851 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
853 struct task_struct
*tsk
;
854 unsigned long *stack
;
855 struct vm_struct
*stack_vm_area __maybe_unused
;
858 if (node
== NUMA_NO_NODE
)
859 node
= tsk_fork_get_node(orig
);
860 tsk
= alloc_task_struct_node(node
);
864 stack
= alloc_thread_stack_node(tsk
, node
);
868 if (memcg_charge_kernel_stack(tsk
))
871 stack_vm_area
= task_stack_vm_area(tsk
);
873 err
= arch_dup_task_struct(tsk
, orig
);
876 * arch_dup_task_struct() clobbers the stack-related fields. Make
877 * sure they're properly initialized before using any stack-related
881 #ifdef CONFIG_VMAP_STACK
882 tsk
->stack_vm_area
= stack_vm_area
;
884 #ifdef CONFIG_THREAD_INFO_IN_TASK
885 refcount_set(&tsk
->stack_refcount
, 1);
891 err
= scs_prepare(tsk
, node
);
895 #ifdef CONFIG_SECCOMP
897 * We must handle setting up seccomp filters once we're under
898 * the sighand lock in case orig has changed between now and
899 * then. Until then, filter must be NULL to avoid messing up
900 * the usage counts on the error path calling free_task.
902 tsk
->seccomp
.filter
= NULL
;
905 setup_thread_stack(tsk
, orig
);
906 clear_user_return_notifier(tsk
);
907 clear_tsk_need_resched(tsk
);
908 set_task_stack_end_magic(tsk
);
909 clear_syscall_work_syscall_user_dispatch(tsk
);
911 #ifdef CONFIG_STACKPROTECTOR
912 tsk
->stack_canary
= get_random_canary();
914 if (orig
->cpus_ptr
== &orig
->cpus_mask
)
915 tsk
->cpus_ptr
= &tsk
->cpus_mask
;
918 * One for the user space visible state that goes away when reaped.
919 * One for the scheduler.
921 refcount_set(&tsk
->rcu_users
, 2);
922 /* One for the rcu users */
923 refcount_set(&tsk
->usage
, 1);
924 #ifdef CONFIG_BLK_DEV_IO_TRACE
927 tsk
->splice_pipe
= NULL
;
928 tsk
->task_frag
.page
= NULL
;
929 tsk
->wake_q
.next
= NULL
;
931 account_kernel_stack(tsk
, 1);
934 kmap_local_fork(tsk
);
936 #ifdef CONFIG_FAULT_INJECTION
940 #ifdef CONFIG_BLK_CGROUP
941 tsk
->throttle_queue
= NULL
;
942 tsk
->use_memdelay
= 0;
946 tsk
->active_memcg
= NULL
;
951 free_thread_stack(tsk
);
953 free_task_struct(tsk
);
957 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
959 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
961 static int __init
coredump_filter_setup(char *s
)
963 default_dump_filter
=
964 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
965 MMF_DUMP_FILTER_MASK
;
969 __setup("coredump_filter=", coredump_filter_setup
);
971 #include <linux/init_task.h>
973 static void mm_init_aio(struct mm_struct
*mm
)
976 spin_lock_init(&mm
->ioctx_lock
);
977 mm
->ioctx_table
= NULL
;
981 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
982 struct task_struct
*p
)
986 WRITE_ONCE(mm
->owner
, NULL
);
990 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
997 static void mm_init_pasid(struct mm_struct
*mm
)
999 #ifdef CONFIG_IOMMU_SUPPORT
1000 mm
->pasid
= INIT_PASID
;
1004 static void mm_init_uprobes_state(struct mm_struct
*mm
)
1006 #ifdef CONFIG_UPROBES
1007 mm
->uprobes_state
.xol_area
= NULL
;
1011 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
1012 struct user_namespace
*user_ns
)
1015 mm
->mm_rb
= RB_ROOT
;
1016 mm
->vmacache_seqnum
= 0;
1017 atomic_set(&mm
->mm_users
, 1);
1018 atomic_set(&mm
->mm_count
, 1);
1019 seqcount_init(&mm
->write_protect_seq
);
1021 INIT_LIST_HEAD(&mm
->mmlist
);
1022 mm
->core_state
= NULL
;
1023 mm_pgtables_bytes_init(mm
);
1026 atomic_set(&mm
->has_pinned
, 0);
1027 atomic64_set(&mm
->pinned_vm
, 0);
1028 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
1029 spin_lock_init(&mm
->page_table_lock
);
1030 spin_lock_init(&mm
->arg_lock
);
1031 mm_init_cpumask(mm
);
1033 mm_init_owner(mm
, p
);
1035 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1036 mmu_notifier_subscriptions_init(mm
);
1037 init_tlb_flush_pending(mm
);
1038 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1039 mm
->pmd_huge_pte
= NULL
;
1041 mm_init_uprobes_state(mm
);
1044 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1045 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1047 mm
->flags
= default_dump_filter
;
1051 if (mm_alloc_pgd(mm
))
1054 if (init_new_context(p
, mm
))
1055 goto fail_nocontext
;
1057 mm
->user_ns
= get_user_ns(user_ns
);
1068 * Allocate and initialize an mm_struct.
1070 struct mm_struct
*mm_alloc(void)
1072 struct mm_struct
*mm
;
1078 memset(mm
, 0, sizeof(*mm
));
1079 return mm_init(mm
, current
, current_user_ns());
1082 static inline void __mmput(struct mm_struct
*mm
)
1084 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1086 uprobe_clear_state(mm
);
1089 khugepaged_exit(mm
); /* must run before exit_mmap */
1091 mm_put_huge_zero_page(mm
);
1092 set_mm_exe_file(mm
, NULL
);
1093 if (!list_empty(&mm
->mmlist
)) {
1094 spin_lock(&mmlist_lock
);
1095 list_del(&mm
->mmlist
);
1096 spin_unlock(&mmlist_lock
);
1099 module_put(mm
->binfmt
->module
);
1104 * Decrement the use count and release all resources for an mm.
1106 void mmput(struct mm_struct
*mm
)
1110 if (atomic_dec_and_test(&mm
->mm_users
))
1113 EXPORT_SYMBOL_GPL(mmput
);
1116 static void mmput_async_fn(struct work_struct
*work
)
1118 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1124 void mmput_async(struct mm_struct
*mm
)
1126 if (atomic_dec_and_test(&mm
->mm_users
)) {
1127 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1128 schedule_work(&mm
->async_put_work
);
1134 * set_mm_exe_file - change a reference to the mm's executable file
1136 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1138 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1139 * invocations: in mmput() nobody alive left, in execve task is single
1140 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1141 * mm->exe_file, but does so without using set_mm_exe_file() in order
1142 * to do avoid the need for any locks.
1144 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1146 struct file
*old_exe_file
;
1149 * It is safe to dereference the exe_file without RCU as
1150 * this function is only called if nobody else can access
1151 * this mm -- see comment above for justification.
1153 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1156 get_file(new_exe_file
);
1157 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1163 * get_mm_exe_file - acquire a reference to the mm's executable file
1165 * Returns %NULL if mm has no associated executable file.
1166 * User must release file via fput().
1168 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1170 struct file
*exe_file
;
1173 exe_file
= rcu_dereference(mm
->exe_file
);
1174 if (exe_file
&& !get_file_rcu(exe_file
))
1179 EXPORT_SYMBOL(get_mm_exe_file
);
1182 * get_task_exe_file - acquire a reference to the task's executable file
1184 * Returns %NULL if task's mm (if any) has no associated executable file or
1185 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1186 * User must release file via fput().
1188 struct file
*get_task_exe_file(struct task_struct
*task
)
1190 struct file
*exe_file
= NULL
;
1191 struct mm_struct
*mm
;
1196 if (!(task
->flags
& PF_KTHREAD
))
1197 exe_file
= get_mm_exe_file(mm
);
1202 EXPORT_SYMBOL(get_task_exe_file
);
1205 * get_task_mm - acquire a reference to the task's mm
1207 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1208 * this kernel workthread has transiently adopted a user mm with use_mm,
1209 * to do its AIO) is not set and if so returns a reference to it, after
1210 * bumping up the use count. User must release the mm via mmput()
1211 * after use. Typically used by /proc and ptrace.
1213 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1215 struct mm_struct
*mm
;
1220 if (task
->flags
& PF_KTHREAD
)
1228 EXPORT_SYMBOL_GPL(get_task_mm
);
1230 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1232 struct mm_struct
*mm
;
1235 err
= down_read_killable(&task
->signal
->exec_update_lock
);
1237 return ERR_PTR(err
);
1239 mm
= get_task_mm(task
);
1240 if (mm
&& mm
!= current
->mm
&&
1241 !ptrace_may_access(task
, mode
)) {
1243 mm
= ERR_PTR(-EACCES
);
1245 up_read(&task
->signal
->exec_update_lock
);
1250 static void complete_vfork_done(struct task_struct
*tsk
)
1252 struct completion
*vfork
;
1255 vfork
= tsk
->vfork_done
;
1256 if (likely(vfork
)) {
1257 tsk
->vfork_done
= NULL
;
1263 static int wait_for_vfork_done(struct task_struct
*child
,
1264 struct completion
*vfork
)
1268 freezer_do_not_count();
1269 cgroup_enter_frozen();
1270 killed
= wait_for_completion_killable(vfork
);
1271 cgroup_leave_frozen(false);
1276 child
->vfork_done
= NULL
;
1280 put_task_struct(child
);
1284 /* Please note the differences between mmput and mm_release.
1285 * mmput is called whenever we stop holding onto a mm_struct,
1286 * error success whatever.
1288 * mm_release is called after a mm_struct has been removed
1289 * from the current process.
1291 * This difference is important for error handling, when we
1292 * only half set up a mm_struct for a new process and need to restore
1293 * the old one. Because we mmput the new mm_struct before
1294 * restoring the old one. . .
1295 * Eric Biederman 10 January 1998
1297 static void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1299 uprobe_free_utask(tsk
);
1301 /* Get rid of any cached register state */
1302 deactivate_mm(tsk
, mm
);
1305 * Signal userspace if we're not exiting with a core dump
1306 * because we want to leave the value intact for debugging
1309 if (tsk
->clear_child_tid
) {
1310 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1311 atomic_read(&mm
->mm_users
) > 1) {
1313 * We don't check the error code - if userspace has
1314 * not set up a proper pointer then tough luck.
1316 put_user(0, tsk
->clear_child_tid
);
1317 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1318 1, NULL
, NULL
, 0, 0);
1320 tsk
->clear_child_tid
= NULL
;
1324 * All done, finally we can wake up parent and return this mm to him.
1325 * Also kthread_stop() uses this completion for synchronization.
1327 if (tsk
->vfork_done
)
1328 complete_vfork_done(tsk
);
1331 void exit_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1333 futex_exit_release(tsk
);
1334 mm_release(tsk
, mm
);
1337 void exec_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1339 futex_exec_release(tsk
);
1340 mm_release(tsk
, mm
);
1344 * dup_mm() - duplicates an existing mm structure
1345 * @tsk: the task_struct with which the new mm will be associated.
1346 * @oldmm: the mm to duplicate.
1348 * Allocates a new mm structure and duplicates the provided @oldmm structure
1351 * Return: the duplicated mm or NULL on failure.
1353 static struct mm_struct
*dup_mm(struct task_struct
*tsk
,
1354 struct mm_struct
*oldmm
)
1356 struct mm_struct
*mm
;
1363 memcpy(mm
, oldmm
, sizeof(*mm
));
1365 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1368 err
= dup_mmap(mm
, oldmm
);
1372 mm
->hiwater_rss
= get_mm_rss(mm
);
1373 mm
->hiwater_vm
= mm
->total_vm
;
1375 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1381 /* don't put binfmt in mmput, we haven't got module yet */
1383 mm_init_owner(mm
, NULL
);
1390 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1392 struct mm_struct
*mm
, *oldmm
;
1395 tsk
->min_flt
= tsk
->maj_flt
= 0;
1396 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1397 #ifdef CONFIG_DETECT_HUNG_TASK
1398 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1399 tsk
->last_switch_time
= 0;
1403 tsk
->active_mm
= NULL
;
1406 * Are we cloning a kernel thread?
1408 * We need to steal a active VM for that..
1410 oldmm
= current
->mm
;
1414 /* initialize the new vmacache entries */
1415 vmacache_flush(tsk
);
1417 if (clone_flags
& CLONE_VM
) {
1424 mm
= dup_mm(tsk
, current
->mm
);
1430 tsk
->active_mm
= mm
;
1437 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1439 struct fs_struct
*fs
= current
->fs
;
1440 if (clone_flags
& CLONE_FS
) {
1441 /* tsk->fs is already what we want */
1442 spin_lock(&fs
->lock
);
1444 spin_unlock(&fs
->lock
);
1448 spin_unlock(&fs
->lock
);
1451 tsk
->fs
= copy_fs_struct(fs
);
1457 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1459 struct files_struct
*oldf
, *newf
;
1463 * A background process may not have any files ...
1465 oldf
= current
->files
;
1469 if (clone_flags
& CLONE_FILES
) {
1470 atomic_inc(&oldf
->count
);
1474 newf
= dup_fd(oldf
, NR_OPEN_MAX
, &error
);
1484 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1487 struct io_context
*ioc
= current
->io_context
;
1488 struct io_context
*new_ioc
;
1493 * Share io context with parent, if CLONE_IO is set
1495 if (clone_flags
& CLONE_IO
) {
1497 tsk
->io_context
= ioc
;
1498 } else if (ioprio_valid(ioc
->ioprio
)) {
1499 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1500 if (unlikely(!new_ioc
))
1503 new_ioc
->ioprio
= ioc
->ioprio
;
1504 put_io_context(new_ioc
);
1510 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1512 struct sighand_struct
*sig
;
1514 if (clone_flags
& CLONE_SIGHAND
) {
1515 refcount_inc(¤t
->sighand
->count
);
1518 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1519 RCU_INIT_POINTER(tsk
->sighand
, sig
);
1523 refcount_set(&sig
->count
, 1);
1524 spin_lock_irq(¤t
->sighand
->siglock
);
1525 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1526 spin_unlock_irq(¤t
->sighand
->siglock
);
1528 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1529 if (clone_flags
& CLONE_CLEAR_SIGHAND
)
1530 flush_signal_handlers(tsk
, 0);
1535 void __cleanup_sighand(struct sighand_struct
*sighand
)
1537 if (refcount_dec_and_test(&sighand
->count
)) {
1538 signalfd_cleanup(sighand
);
1540 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1541 * without an RCU grace period, see __lock_task_sighand().
1543 kmem_cache_free(sighand_cachep
, sighand
);
1548 * Initialize POSIX timer handling for a thread group.
1550 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1552 struct posix_cputimers
*pct
= &sig
->posix_cputimers
;
1553 unsigned long cpu_limit
;
1555 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1556 posix_cputimers_group_init(pct
, cpu_limit
);
1559 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1561 struct signal_struct
*sig
;
1563 if (clone_flags
& CLONE_THREAD
)
1566 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1571 sig
->nr_threads
= 1;
1572 atomic_set(&sig
->live
, 1);
1573 refcount_set(&sig
->sigcnt
, 1);
1575 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1576 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1577 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1579 init_waitqueue_head(&sig
->wait_chldexit
);
1580 sig
->curr_target
= tsk
;
1581 init_sigpending(&sig
->shared_pending
);
1582 INIT_HLIST_HEAD(&sig
->multiprocess
);
1583 seqlock_init(&sig
->stats_lock
);
1584 prev_cputime_init(&sig
->prev_cputime
);
1586 #ifdef CONFIG_POSIX_TIMERS
1587 INIT_LIST_HEAD(&sig
->posix_timers
);
1588 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1589 sig
->real_timer
.function
= it_real_fn
;
1592 task_lock(current
->group_leader
);
1593 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1594 task_unlock(current
->group_leader
);
1596 posix_cpu_timers_init_group(sig
);
1598 tty_audit_fork(sig
);
1599 sched_autogroup_fork(sig
);
1601 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1602 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1604 mutex_init(&sig
->cred_guard_mutex
);
1605 init_rwsem(&sig
->exec_update_lock
);
1610 static void copy_seccomp(struct task_struct
*p
)
1612 #ifdef CONFIG_SECCOMP
1614 * Must be called with sighand->lock held, which is common to
1615 * all threads in the group. Holding cred_guard_mutex is not
1616 * needed because this new task is not yet running and cannot
1619 assert_spin_locked(¤t
->sighand
->siglock
);
1621 /* Ref-count the new filter user, and assign it. */
1622 get_seccomp_filter(current
);
1623 p
->seccomp
= current
->seccomp
;
1626 * Explicitly enable no_new_privs here in case it got set
1627 * between the task_struct being duplicated and holding the
1628 * sighand lock. The seccomp state and nnp must be in sync.
1630 if (task_no_new_privs(current
))
1631 task_set_no_new_privs(p
);
1634 * If the parent gained a seccomp mode after copying thread
1635 * flags and between before we held the sighand lock, we have
1636 * to manually enable the seccomp thread flag here.
1638 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1639 set_task_syscall_work(p
, SECCOMP
);
1643 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1645 current
->clear_child_tid
= tidptr
;
1647 return task_pid_vnr(current
);
1650 static void rt_mutex_init_task(struct task_struct
*p
)
1652 raw_spin_lock_init(&p
->pi_lock
);
1653 #ifdef CONFIG_RT_MUTEXES
1654 p
->pi_waiters
= RB_ROOT_CACHED
;
1655 p
->pi_top_task
= NULL
;
1656 p
->pi_blocked_on
= NULL
;
1660 static inline void init_task_pid_links(struct task_struct
*task
)
1664 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
)
1665 INIT_HLIST_NODE(&task
->pid_links
[type
]);
1669 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1671 if (type
== PIDTYPE_PID
)
1672 task
->thread_pid
= pid
;
1674 task
->signal
->pids
[type
] = pid
;
1677 static inline void rcu_copy_process(struct task_struct
*p
)
1679 #ifdef CONFIG_PREEMPT_RCU
1680 p
->rcu_read_lock_nesting
= 0;
1681 p
->rcu_read_unlock_special
.s
= 0;
1682 p
->rcu_blocked_node
= NULL
;
1683 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1684 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1685 #ifdef CONFIG_TASKS_RCU
1686 p
->rcu_tasks_holdout
= false;
1687 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1688 p
->rcu_tasks_idle_cpu
= -1;
1689 #endif /* #ifdef CONFIG_TASKS_RCU */
1690 #ifdef CONFIG_TASKS_TRACE_RCU
1691 p
->trc_reader_nesting
= 0;
1692 p
->trc_reader_special
.s
= 0;
1693 INIT_LIST_HEAD(&p
->trc_holdout_list
);
1694 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1697 struct pid
*pidfd_pid(const struct file
*file
)
1699 if (file
->f_op
== &pidfd_fops
)
1700 return file
->private_data
;
1702 return ERR_PTR(-EBADF
);
1705 static int pidfd_release(struct inode
*inode
, struct file
*file
)
1707 struct pid
*pid
= file
->private_data
;
1709 file
->private_data
= NULL
;
1714 #ifdef CONFIG_PROC_FS
1716 * pidfd_show_fdinfo - print information about a pidfd
1717 * @m: proc fdinfo file
1718 * @f: file referencing a pidfd
1721 * This function will print the pid that a given pidfd refers to in the
1722 * pid namespace of the procfs instance.
1723 * If the pid namespace of the process is not a descendant of the pid
1724 * namespace of the procfs instance 0 will be shown as its pid. This is
1725 * similar to calling getppid() on a process whose parent is outside of
1726 * its pid namespace.
1729 * If pid namespaces are supported then this function will also print
1730 * the pid of a given pidfd refers to for all descendant pid namespaces
1731 * starting from the current pid namespace of the instance, i.e. the
1732 * Pid field and the first entry in the NSpid field will be identical.
1733 * If the pid namespace of the process is not a descendant of the pid
1734 * namespace of the procfs instance 0 will be shown as its first NSpid
1735 * entry and no others will be shown.
1736 * Note that this differs from the Pid and NSpid fields in
1737 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1738 * the pid namespace of the procfs instance. The difference becomes
1739 * obvious when sending around a pidfd between pid namespaces from a
1740 * different branch of the tree, i.e. where no ancestoral relation is
1741 * present between the pid namespaces:
1742 * - create two new pid namespaces ns1 and ns2 in the initial pid
1743 * namespace (also take care to create new mount namespaces in the
1744 * new pid namespace and mount procfs)
1745 * - create a process with a pidfd in ns1
1746 * - send pidfd from ns1 to ns2
1747 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1748 * have exactly one entry, which is 0
1750 static void pidfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
1752 struct pid
*pid
= f
->private_data
;
1753 struct pid_namespace
*ns
;
1756 if (likely(pid_has_task(pid
, PIDTYPE_PID
))) {
1757 ns
= proc_pid_ns(file_inode(m
->file
)->i_sb
);
1758 nr
= pid_nr_ns(pid
, ns
);
1761 seq_put_decimal_ll(m
, "Pid:\t", nr
);
1763 #ifdef CONFIG_PID_NS
1764 seq_put_decimal_ll(m
, "\nNSpid:\t", nr
);
1768 /* If nr is non-zero it means that 'pid' is valid and that
1769 * ns, i.e. the pid namespace associated with the procfs
1770 * instance, is in the pid namespace hierarchy of pid.
1771 * Start at one below the already printed level.
1773 for (i
= ns
->level
+ 1; i
<= pid
->level
; i
++)
1774 seq_put_decimal_ll(m
, "\t", pid
->numbers
[i
].nr
);
1782 * Poll support for process exit notification.
1784 static __poll_t
pidfd_poll(struct file
*file
, struct poll_table_struct
*pts
)
1786 struct pid
*pid
= file
->private_data
;
1787 __poll_t poll_flags
= 0;
1789 poll_wait(file
, &pid
->wait_pidfd
, pts
);
1792 * Inform pollers only when the whole thread group exits.
1793 * If the thread group leader exits before all other threads in the
1794 * group, then poll(2) should block, similar to the wait(2) family.
1796 if (thread_group_exited(pid
))
1797 poll_flags
= EPOLLIN
| EPOLLRDNORM
;
1802 const struct file_operations pidfd_fops
= {
1803 .release
= pidfd_release
,
1805 #ifdef CONFIG_PROC_FS
1806 .show_fdinfo
= pidfd_show_fdinfo
,
1810 static void __delayed_free_task(struct rcu_head
*rhp
)
1812 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
1817 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
1819 if (IS_ENABLED(CONFIG_MEMCG
))
1820 call_rcu(&tsk
->rcu
, __delayed_free_task
);
1825 static void copy_oom_score_adj(u64 clone_flags
, struct task_struct
*tsk
)
1827 /* Skip if kernel thread */
1831 /* Skip if spawning a thread or using vfork */
1832 if ((clone_flags
& (CLONE_VM
| CLONE_THREAD
| CLONE_VFORK
)) != CLONE_VM
)
1835 /* We need to synchronize with __set_oom_adj */
1836 mutex_lock(&oom_adj_mutex
);
1837 set_bit(MMF_MULTIPROCESS
, &tsk
->mm
->flags
);
1838 /* Update the values in case they were changed after copy_signal */
1839 tsk
->signal
->oom_score_adj
= current
->signal
->oom_score_adj
;
1840 tsk
->signal
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1841 mutex_unlock(&oom_adj_mutex
);
1845 * This creates a new process as a copy of the old one,
1846 * but does not actually start it yet.
1848 * It copies the registers, and all the appropriate
1849 * parts of the process environment (as per the clone
1850 * flags). The actual kick-off is left to the caller.
1852 static __latent_entropy
struct task_struct
*copy_process(
1856 struct kernel_clone_args
*args
)
1858 int pidfd
= -1, retval
;
1859 struct task_struct
*p
;
1860 struct multiprocess_signals delayed
;
1861 struct file
*pidfile
= NULL
;
1862 u64 clone_flags
= args
->flags
;
1863 struct nsproxy
*nsp
= current
->nsproxy
;
1866 * Don't allow sharing the root directory with processes in a different
1869 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1870 return ERR_PTR(-EINVAL
);
1872 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1873 return ERR_PTR(-EINVAL
);
1876 * Thread groups must share signals as well, and detached threads
1877 * can only be started up within the thread group.
1879 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1880 return ERR_PTR(-EINVAL
);
1883 * Shared signal handlers imply shared VM. By way of the above,
1884 * thread groups also imply shared VM. Blocking this case allows
1885 * for various simplifications in other code.
1887 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1888 return ERR_PTR(-EINVAL
);
1891 * Siblings of global init remain as zombies on exit since they are
1892 * not reaped by their parent (swapper). To solve this and to avoid
1893 * multi-rooted process trees, prevent global and container-inits
1894 * from creating siblings.
1896 if ((clone_flags
& CLONE_PARENT
) &&
1897 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1898 return ERR_PTR(-EINVAL
);
1901 * If the new process will be in a different pid or user namespace
1902 * do not allow it to share a thread group with the forking task.
1904 if (clone_flags
& CLONE_THREAD
) {
1905 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1906 (task_active_pid_ns(current
) != nsp
->pid_ns_for_children
))
1907 return ERR_PTR(-EINVAL
);
1911 * If the new process will be in a different time namespace
1912 * do not allow it to share VM or a thread group with the forking task.
1914 if (clone_flags
& (CLONE_THREAD
| CLONE_VM
)) {
1915 if (nsp
->time_ns
!= nsp
->time_ns_for_children
)
1916 return ERR_PTR(-EINVAL
);
1919 if (clone_flags
& CLONE_PIDFD
) {
1921 * - CLONE_DETACHED is blocked so that we can potentially
1922 * reuse it later for CLONE_PIDFD.
1923 * - CLONE_THREAD is blocked until someone really needs it.
1925 if (clone_flags
& (CLONE_DETACHED
| CLONE_THREAD
))
1926 return ERR_PTR(-EINVAL
);
1930 * Force any signals received before this point to be delivered
1931 * before the fork happens. Collect up signals sent to multiple
1932 * processes that happen during the fork and delay them so that
1933 * they appear to happen after the fork.
1935 sigemptyset(&delayed
.signal
);
1936 INIT_HLIST_NODE(&delayed
.node
);
1938 spin_lock_irq(¤t
->sighand
->siglock
);
1939 if (!(clone_flags
& CLONE_THREAD
))
1940 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
1941 recalc_sigpending();
1942 spin_unlock_irq(¤t
->sighand
->siglock
);
1943 retval
= -ERESTARTNOINTR
;
1944 if (signal_pending(current
))
1948 p
= dup_task_struct(current
, node
);
1951 if (args
->io_thread
)
1952 p
->flags
|= PF_IO_WORKER
;
1955 * This _must_ happen before we call free_task(), i.e. before we jump
1956 * to any of the bad_fork_* labels. This is to avoid freeing
1957 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1958 * kernel threads (PF_KTHREAD).
1960 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? args
->child_tid
: NULL
;
1962 * Clear TID on mm_release()?
1964 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? args
->child_tid
: NULL
;
1966 ftrace_graph_init_task(p
);
1968 rt_mutex_init_task(p
);
1970 lockdep_assert_irqs_enabled();
1971 #ifdef CONFIG_PROVE_LOCKING
1972 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1975 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1976 task_rlimit(p
, RLIMIT_NPROC
)) {
1977 if (p
->real_cred
->user
!= INIT_USER
&&
1978 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1981 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1983 retval
= copy_creds(p
, clone_flags
);
1988 * If multiple threads are within copy_process(), then this check
1989 * triggers too late. This doesn't hurt, the check is only there
1990 * to stop root fork bombs.
1993 if (data_race(nr_threads
>= max_threads
))
1994 goto bad_fork_cleanup_count
;
1996 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1997 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1998 p
->flags
|= PF_FORKNOEXEC
;
1999 INIT_LIST_HEAD(&p
->children
);
2000 INIT_LIST_HEAD(&p
->sibling
);
2001 rcu_copy_process(p
);
2002 p
->vfork_done
= NULL
;
2003 spin_lock_init(&p
->alloc_lock
);
2005 init_sigpending(&p
->pending
);
2007 p
->utime
= p
->stime
= p
->gtime
= 0;
2008 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2009 p
->utimescaled
= p
->stimescaled
= 0;
2011 prev_cputime_init(&p
->prev_cputime
);
2013 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2014 seqcount_init(&p
->vtime
.seqcount
);
2015 p
->vtime
.starttime
= 0;
2016 p
->vtime
.state
= VTIME_INACTIVE
;
2019 #ifdef CONFIG_IO_URING
2023 #if defined(SPLIT_RSS_COUNTING)
2024 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
2027 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
2033 task_io_accounting_init(&p
->ioac
);
2034 acct_clear_integrals(p
);
2036 posix_cputimers_init(&p
->posix_cputimers
);
2038 p
->io_context
= NULL
;
2039 audit_set_context(p
, NULL
);
2042 p
->mempolicy
= mpol_dup(p
->mempolicy
);
2043 if (IS_ERR(p
->mempolicy
)) {
2044 retval
= PTR_ERR(p
->mempolicy
);
2045 p
->mempolicy
= NULL
;
2046 goto bad_fork_cleanup_threadgroup_lock
;
2049 #ifdef CONFIG_CPUSETS
2050 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
2051 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
2052 seqcount_spinlock_init(&p
->mems_allowed_seq
, &p
->alloc_lock
);
2054 #ifdef CONFIG_TRACE_IRQFLAGS
2055 memset(&p
->irqtrace
, 0, sizeof(p
->irqtrace
));
2056 p
->irqtrace
.hardirq_disable_ip
= _THIS_IP_
;
2057 p
->irqtrace
.softirq_enable_ip
= _THIS_IP_
;
2058 p
->softirqs_enabled
= 1;
2059 p
->softirq_context
= 0;
2062 p
->pagefault_disabled
= 0;
2064 #ifdef CONFIG_LOCKDEP
2065 lockdep_init_task(p
);
2068 #ifdef CONFIG_DEBUG_MUTEXES
2069 p
->blocked_on
= NULL
; /* not blocked yet */
2071 #ifdef CONFIG_BCACHE
2072 p
->sequential_io
= 0;
2073 p
->sequential_io_avg
= 0;
2076 /* Perform scheduler related setup. Assign this task to a CPU. */
2077 retval
= sched_fork(clone_flags
, p
);
2079 goto bad_fork_cleanup_policy
;
2081 retval
= perf_event_init_task(p
);
2083 goto bad_fork_cleanup_policy
;
2084 retval
= audit_alloc(p
);
2086 goto bad_fork_cleanup_perf
;
2087 /* copy all the process information */
2089 retval
= security_task_alloc(p
, clone_flags
);
2091 goto bad_fork_cleanup_audit
;
2092 retval
= copy_semundo(clone_flags
, p
);
2094 goto bad_fork_cleanup_security
;
2095 retval
= copy_files(clone_flags
, p
);
2097 goto bad_fork_cleanup_semundo
;
2098 retval
= copy_fs(clone_flags
, p
);
2100 goto bad_fork_cleanup_files
;
2101 retval
= copy_sighand(clone_flags
, p
);
2103 goto bad_fork_cleanup_fs
;
2104 retval
= copy_signal(clone_flags
, p
);
2106 goto bad_fork_cleanup_sighand
;
2107 retval
= copy_mm(clone_flags
, p
);
2109 goto bad_fork_cleanup_signal
;
2110 retval
= copy_namespaces(clone_flags
, p
);
2112 goto bad_fork_cleanup_mm
;
2113 retval
= copy_io(clone_flags
, p
);
2115 goto bad_fork_cleanup_namespaces
;
2116 retval
= copy_thread(clone_flags
, args
->stack
, args
->stack_size
, p
, args
->tls
);
2118 goto bad_fork_cleanup_io
;
2120 stackleak_task_init(p
);
2122 if (pid
!= &init_struct_pid
) {
2123 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
, args
->set_tid
,
2124 args
->set_tid_size
);
2126 retval
= PTR_ERR(pid
);
2127 goto bad_fork_cleanup_thread
;
2132 * This has to happen after we've potentially unshared the file
2133 * descriptor table (so that the pidfd doesn't leak into the child
2134 * if the fd table isn't shared).
2136 if (clone_flags
& CLONE_PIDFD
) {
2137 retval
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2139 goto bad_fork_free_pid
;
2143 pidfile
= anon_inode_getfile("[pidfd]", &pidfd_fops
, pid
,
2144 O_RDWR
| O_CLOEXEC
);
2145 if (IS_ERR(pidfile
)) {
2146 put_unused_fd(pidfd
);
2147 retval
= PTR_ERR(pidfile
);
2148 goto bad_fork_free_pid
;
2150 get_pid(pid
); /* held by pidfile now */
2152 retval
= put_user(pidfd
, args
->pidfd
);
2154 goto bad_fork_put_pidfd
;
2163 * sigaltstack should be cleared when sharing the same VM
2165 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
2169 * Syscall tracing and stepping should be turned off in the
2170 * child regardless of CLONE_PTRACE.
2172 user_disable_single_step(p
);
2173 clear_task_syscall_work(p
, SYSCALL_TRACE
);
2174 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2175 clear_task_syscall_work(p
, SYSCALL_EMU
);
2177 clear_tsk_latency_tracing(p
);
2179 /* ok, now we should be set up.. */
2180 p
->pid
= pid_nr(pid
);
2181 if (clone_flags
& CLONE_THREAD
) {
2182 p
->group_leader
= current
->group_leader
;
2183 p
->tgid
= current
->tgid
;
2185 p
->group_leader
= p
;
2190 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2191 p
->dirty_paused_when
= 0;
2193 p
->pdeath_signal
= 0;
2194 INIT_LIST_HEAD(&p
->thread_group
);
2195 p
->task_works
= NULL
;
2197 #ifdef CONFIG_KRETPROBES
2198 p
->kretprobe_instances
.first
= NULL
;
2202 * Ensure that the cgroup subsystem policies allow the new process to be
2203 * forked. It should be noted that the new process's css_set can be changed
2204 * between here and cgroup_post_fork() if an organisation operation is in
2207 retval
= cgroup_can_fork(p
, args
);
2209 goto bad_fork_put_pidfd
;
2212 * From this point on we must avoid any synchronous user-space
2213 * communication until we take the tasklist-lock. In particular, we do
2214 * not want user-space to be able to predict the process start-time by
2215 * stalling fork(2) after we recorded the start_time but before it is
2216 * visible to the system.
2219 p
->start_time
= ktime_get_ns();
2220 p
->start_boottime
= ktime_get_boottime_ns();
2223 * Make it visible to the rest of the system, but dont wake it up yet.
2224 * Need tasklist lock for parent etc handling!
2226 write_lock_irq(&tasklist_lock
);
2228 /* CLONE_PARENT re-uses the old parent */
2229 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2230 p
->real_parent
= current
->real_parent
;
2231 p
->parent_exec_id
= current
->parent_exec_id
;
2232 if (clone_flags
& CLONE_THREAD
)
2233 p
->exit_signal
= -1;
2235 p
->exit_signal
= current
->group_leader
->exit_signal
;
2237 p
->real_parent
= current
;
2238 p
->parent_exec_id
= current
->self_exec_id
;
2239 p
->exit_signal
= args
->exit_signal
;
2242 klp_copy_process(p
);
2244 spin_lock(¤t
->sighand
->siglock
);
2247 * Copy seccomp details explicitly here, in case they were changed
2248 * before holding sighand lock.
2252 rseq_fork(p
, clone_flags
);
2254 /* Don't start children in a dying pid namespace */
2255 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2257 goto bad_fork_cancel_cgroup
;
2260 /* Let kill terminate clone/fork in the middle */
2261 if (fatal_signal_pending(current
)) {
2263 goto bad_fork_cancel_cgroup
;
2266 /* past the last point of failure */
2268 fd_install(pidfd
, pidfile
);
2270 init_task_pid_links(p
);
2271 if (likely(p
->pid
)) {
2272 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2274 init_task_pid(p
, PIDTYPE_PID
, pid
);
2275 if (thread_group_leader(p
)) {
2276 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2277 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2278 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2280 if (is_child_reaper(pid
)) {
2281 ns_of_pid(pid
)->child_reaper
= p
;
2282 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2284 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2285 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2287 * Inherit has_child_subreaper flag under the same
2288 * tasklist_lock with adding child to the process tree
2289 * for propagate_has_child_subreaper optimization.
2291 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2292 p
->real_parent
->signal
->is_child_subreaper
;
2293 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2294 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2295 attach_pid(p
, PIDTYPE_TGID
);
2296 attach_pid(p
, PIDTYPE_PGID
);
2297 attach_pid(p
, PIDTYPE_SID
);
2298 __this_cpu_inc(process_counts
);
2300 current
->signal
->nr_threads
++;
2301 atomic_inc(¤t
->signal
->live
);
2302 refcount_inc(¤t
->signal
->sigcnt
);
2303 task_join_group_stop(p
);
2304 list_add_tail_rcu(&p
->thread_group
,
2305 &p
->group_leader
->thread_group
);
2306 list_add_tail_rcu(&p
->thread_node
,
2307 &p
->signal
->thread_head
);
2309 attach_pid(p
, PIDTYPE_PID
);
2313 hlist_del_init(&delayed
.node
);
2314 spin_unlock(¤t
->sighand
->siglock
);
2315 syscall_tracepoint_update(p
);
2316 write_unlock_irq(&tasklist_lock
);
2318 proc_fork_connector(p
);
2320 cgroup_post_fork(p
, args
);
2323 trace_task_newtask(p
, clone_flags
);
2324 uprobe_copy_process(p
, clone_flags
);
2326 copy_oom_score_adj(clone_flags
, p
);
2330 bad_fork_cancel_cgroup
:
2331 spin_unlock(¤t
->sighand
->siglock
);
2332 write_unlock_irq(&tasklist_lock
);
2333 cgroup_cancel_fork(p
, args
);
2335 if (clone_flags
& CLONE_PIDFD
) {
2337 put_unused_fd(pidfd
);
2340 if (pid
!= &init_struct_pid
)
2342 bad_fork_cleanup_thread
:
2344 bad_fork_cleanup_io
:
2347 bad_fork_cleanup_namespaces
:
2348 exit_task_namespaces(p
);
2349 bad_fork_cleanup_mm
:
2351 mm_clear_owner(p
->mm
, p
);
2354 bad_fork_cleanup_signal
:
2355 if (!(clone_flags
& CLONE_THREAD
))
2356 free_signal_struct(p
->signal
);
2357 bad_fork_cleanup_sighand
:
2358 __cleanup_sighand(p
->sighand
);
2359 bad_fork_cleanup_fs
:
2360 exit_fs(p
); /* blocking */
2361 bad_fork_cleanup_files
:
2362 exit_files(p
); /* blocking */
2363 bad_fork_cleanup_semundo
:
2365 bad_fork_cleanup_security
:
2366 security_task_free(p
);
2367 bad_fork_cleanup_audit
:
2369 bad_fork_cleanup_perf
:
2370 perf_event_free_task(p
);
2371 bad_fork_cleanup_policy
:
2372 lockdep_free_task(p
);
2374 mpol_put(p
->mempolicy
);
2375 bad_fork_cleanup_threadgroup_lock
:
2377 delayacct_tsk_free(p
);
2378 bad_fork_cleanup_count
:
2379 atomic_dec(&p
->cred
->user
->processes
);
2382 p
->state
= TASK_DEAD
;
2384 delayed_free_task(p
);
2386 spin_lock_irq(¤t
->sighand
->siglock
);
2387 hlist_del_init(&delayed
.node
);
2388 spin_unlock_irq(¤t
->sighand
->siglock
);
2389 return ERR_PTR(retval
);
2392 static inline void init_idle_pids(struct task_struct
*idle
)
2396 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2397 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2398 init_task_pid(idle
, type
, &init_struct_pid
);
2402 struct task_struct
*fork_idle(int cpu
)
2404 struct task_struct
*task
;
2405 struct kernel_clone_args args
= {
2409 task
= copy_process(&init_struct_pid
, 0, cpu_to_node(cpu
), &args
);
2410 if (!IS_ERR(task
)) {
2411 init_idle_pids(task
);
2412 init_idle(task
, cpu
);
2418 struct mm_struct
*copy_init_mm(void)
2420 return dup_mm(NULL
, &init_mm
);
2424 * This is like kernel_clone(), but shaved down and tailored to just
2425 * creating io_uring workers. It returns a created task, or an error pointer.
2426 * The returned task is inactive, and the caller must fire it up through
2427 * wake_up_new_task(p). All signals are blocked in the created task.
2429 struct task_struct
*create_io_thread(int (*fn
)(void *), void *arg
, int node
)
2431 unsigned long flags
= CLONE_FS
|CLONE_FILES
|CLONE_SIGHAND
|CLONE_THREAD
|
2433 struct kernel_clone_args args
= {
2434 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2435 CLONE_UNTRACED
) & ~CSIGNAL
),
2436 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2437 .stack
= (unsigned long)fn
,
2438 .stack_size
= (unsigned long)arg
,
2441 struct task_struct
*tsk
;
2443 tsk
= copy_process(NULL
, 0, node
, &args
);
2445 sigfillset(&tsk
->blocked
);
2446 sigdelsetmask(&tsk
->blocked
, sigmask(SIGKILL
));
2452 * Ok, this is the main fork-routine.
2454 * It copies the process, and if successful kick-starts
2455 * it and waits for it to finish using the VM if required.
2457 * args->exit_signal is expected to be checked for sanity by the caller.
2459 pid_t
kernel_clone(struct kernel_clone_args
*args
)
2461 u64 clone_flags
= args
->flags
;
2462 struct completion vfork
;
2464 struct task_struct
*p
;
2469 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2470 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2471 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2472 * field in struct clone_args and it still doesn't make sense to have
2473 * them both point at the same memory location. Performing this check
2474 * here has the advantage that we don't need to have a separate helper
2475 * to check for legacy clone().
2477 if ((args
->flags
& CLONE_PIDFD
) &&
2478 (args
->flags
& CLONE_PARENT_SETTID
) &&
2479 (args
->pidfd
== args
->parent_tid
))
2483 * Determine whether and which event to report to ptracer. When
2484 * called from kernel_thread or CLONE_UNTRACED is explicitly
2485 * requested, no event is reported; otherwise, report if the event
2486 * for the type of forking is enabled.
2488 if (!(clone_flags
& CLONE_UNTRACED
)) {
2489 if (clone_flags
& CLONE_VFORK
)
2490 trace
= PTRACE_EVENT_VFORK
;
2491 else if (args
->exit_signal
!= SIGCHLD
)
2492 trace
= PTRACE_EVENT_CLONE
;
2494 trace
= PTRACE_EVENT_FORK
;
2496 if (likely(!ptrace_event_enabled(current
, trace
)))
2500 p
= copy_process(NULL
, trace
, NUMA_NO_NODE
, args
);
2501 add_latent_entropy();
2507 * Do this prior waking up the new thread - the thread pointer
2508 * might get invalid after that point, if the thread exits quickly.
2510 trace_sched_process_fork(current
, p
);
2512 pid
= get_task_pid(p
, PIDTYPE_PID
);
2515 if (clone_flags
& CLONE_PARENT_SETTID
)
2516 put_user(nr
, args
->parent_tid
);
2518 if (clone_flags
& CLONE_VFORK
) {
2519 p
->vfork_done
= &vfork
;
2520 init_completion(&vfork
);
2524 wake_up_new_task(p
);
2526 /* forking complete and child started to run, tell ptracer */
2527 if (unlikely(trace
))
2528 ptrace_event_pid(trace
, pid
);
2530 if (clone_flags
& CLONE_VFORK
) {
2531 if (!wait_for_vfork_done(p
, &vfork
))
2532 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2540 * Create a kernel thread.
2542 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2544 struct kernel_clone_args args
= {
2545 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2546 CLONE_UNTRACED
) & ~CSIGNAL
),
2547 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2548 .stack
= (unsigned long)fn
,
2549 .stack_size
= (unsigned long)arg
,
2552 return kernel_clone(&args
);
2555 #ifdef __ARCH_WANT_SYS_FORK
2556 SYSCALL_DEFINE0(fork
)
2559 struct kernel_clone_args args
= {
2560 .exit_signal
= SIGCHLD
,
2563 return kernel_clone(&args
);
2565 /* can not support in nommu mode */
2571 #ifdef __ARCH_WANT_SYS_VFORK
2572 SYSCALL_DEFINE0(vfork
)
2574 struct kernel_clone_args args
= {
2575 .flags
= CLONE_VFORK
| CLONE_VM
,
2576 .exit_signal
= SIGCHLD
,
2579 return kernel_clone(&args
);
2583 #ifdef __ARCH_WANT_SYS_CLONE
2584 #ifdef CONFIG_CLONE_BACKWARDS
2585 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2586 int __user
*, parent_tidptr
,
2588 int __user
*, child_tidptr
)
2589 #elif defined(CONFIG_CLONE_BACKWARDS2)
2590 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2591 int __user
*, parent_tidptr
,
2592 int __user
*, child_tidptr
,
2594 #elif defined(CONFIG_CLONE_BACKWARDS3)
2595 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2597 int __user
*, parent_tidptr
,
2598 int __user
*, child_tidptr
,
2601 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2602 int __user
*, parent_tidptr
,
2603 int __user
*, child_tidptr
,
2607 struct kernel_clone_args args
= {
2608 .flags
= (lower_32_bits(clone_flags
) & ~CSIGNAL
),
2609 .pidfd
= parent_tidptr
,
2610 .child_tid
= child_tidptr
,
2611 .parent_tid
= parent_tidptr
,
2612 .exit_signal
= (lower_32_bits(clone_flags
) & CSIGNAL
),
2617 return kernel_clone(&args
);
2621 #ifdef __ARCH_WANT_SYS_CLONE3
2623 noinline
static int copy_clone_args_from_user(struct kernel_clone_args
*kargs
,
2624 struct clone_args __user
*uargs
,
2628 struct clone_args args
;
2629 pid_t
*kset_tid
= kargs
->set_tid
;
2631 BUILD_BUG_ON(offsetofend(struct clone_args
, tls
) !=
2632 CLONE_ARGS_SIZE_VER0
);
2633 BUILD_BUG_ON(offsetofend(struct clone_args
, set_tid_size
) !=
2634 CLONE_ARGS_SIZE_VER1
);
2635 BUILD_BUG_ON(offsetofend(struct clone_args
, cgroup
) !=
2636 CLONE_ARGS_SIZE_VER2
);
2637 BUILD_BUG_ON(sizeof(struct clone_args
) != CLONE_ARGS_SIZE_VER2
);
2639 if (unlikely(usize
> PAGE_SIZE
))
2641 if (unlikely(usize
< CLONE_ARGS_SIZE_VER0
))
2644 err
= copy_struct_from_user(&args
, sizeof(args
), uargs
, usize
);
2648 if (unlikely(args
.set_tid_size
> MAX_PID_NS_LEVEL
))
2651 if (unlikely(!args
.set_tid
&& args
.set_tid_size
> 0))
2654 if (unlikely(args
.set_tid
&& args
.set_tid_size
== 0))
2658 * Verify that higher 32bits of exit_signal are unset and that
2659 * it is a valid signal
2661 if (unlikely((args
.exit_signal
& ~((u64
)CSIGNAL
)) ||
2662 !valid_signal(args
.exit_signal
)))
2665 if ((args
.flags
& CLONE_INTO_CGROUP
) &&
2666 (args
.cgroup
> INT_MAX
|| usize
< CLONE_ARGS_SIZE_VER2
))
2669 *kargs
= (struct kernel_clone_args
){
2670 .flags
= args
.flags
,
2671 .pidfd
= u64_to_user_ptr(args
.pidfd
),
2672 .child_tid
= u64_to_user_ptr(args
.child_tid
),
2673 .parent_tid
= u64_to_user_ptr(args
.parent_tid
),
2674 .exit_signal
= args
.exit_signal
,
2675 .stack
= args
.stack
,
2676 .stack_size
= args
.stack_size
,
2678 .set_tid_size
= args
.set_tid_size
,
2679 .cgroup
= args
.cgroup
,
2683 copy_from_user(kset_tid
, u64_to_user_ptr(args
.set_tid
),
2684 (kargs
->set_tid_size
* sizeof(pid_t
))))
2687 kargs
->set_tid
= kset_tid
;
2693 * clone3_stack_valid - check and prepare stack
2694 * @kargs: kernel clone args
2696 * Verify that the stack arguments userspace gave us are sane.
2697 * In addition, set the stack direction for userspace since it's easy for us to
2700 static inline bool clone3_stack_valid(struct kernel_clone_args
*kargs
)
2702 if (kargs
->stack
== 0) {
2703 if (kargs
->stack_size
> 0)
2706 if (kargs
->stack_size
== 0)
2709 if (!access_ok((void __user
*)kargs
->stack
, kargs
->stack_size
))
2712 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2713 kargs
->stack
+= kargs
->stack_size
;
2720 static bool clone3_args_valid(struct kernel_clone_args
*kargs
)
2722 /* Verify that no unknown flags are passed along. */
2724 ~(CLONE_LEGACY_FLAGS
| CLONE_CLEAR_SIGHAND
| CLONE_INTO_CGROUP
))
2728 * - make the CLONE_DETACHED bit reuseable for clone3
2729 * - make the CSIGNAL bits reuseable for clone3
2731 if (kargs
->flags
& (CLONE_DETACHED
| CSIGNAL
))
2734 if ((kargs
->flags
& (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
)) ==
2735 (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
))
2738 if ((kargs
->flags
& (CLONE_THREAD
| CLONE_PARENT
)) &&
2742 if (!clone3_stack_valid(kargs
))
2749 * clone3 - create a new process with specific properties
2750 * @uargs: argument structure
2751 * @size: size of @uargs
2753 * clone3() is the extensible successor to clone()/clone2().
2754 * It takes a struct as argument that is versioned by its size.
2756 * Return: On success, a positive PID for the child process.
2757 * On error, a negative errno number.
2759 SYSCALL_DEFINE2(clone3
, struct clone_args __user
*, uargs
, size_t, size
)
2763 struct kernel_clone_args kargs
;
2764 pid_t set_tid
[MAX_PID_NS_LEVEL
];
2766 kargs
.set_tid
= set_tid
;
2768 err
= copy_clone_args_from_user(&kargs
, uargs
, size
);
2772 if (!clone3_args_valid(&kargs
))
2775 return kernel_clone(&kargs
);
2779 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2781 struct task_struct
*leader
, *parent
, *child
;
2784 read_lock(&tasklist_lock
);
2785 leader
= top
= top
->group_leader
;
2787 for_each_thread(leader
, parent
) {
2788 list_for_each_entry(child
, &parent
->children
, sibling
) {
2789 res
= visitor(child
, data
);
2801 if (leader
!= top
) {
2803 parent
= child
->real_parent
;
2804 leader
= parent
->group_leader
;
2808 read_unlock(&tasklist_lock
);
2811 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2812 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2815 static void sighand_ctor(void *data
)
2817 struct sighand_struct
*sighand
= data
;
2819 spin_lock_init(&sighand
->siglock
);
2820 init_waitqueue_head(&sighand
->signalfd_wqh
);
2823 void __init
proc_caches_init(void)
2825 unsigned int mm_size
;
2827 sighand_cachep
= kmem_cache_create("sighand_cache",
2828 sizeof(struct sighand_struct
), 0,
2829 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
2830 SLAB_ACCOUNT
, sighand_ctor
);
2831 signal_cachep
= kmem_cache_create("signal_cache",
2832 sizeof(struct signal_struct
), 0,
2833 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2835 files_cachep
= kmem_cache_create("files_cache",
2836 sizeof(struct files_struct
), 0,
2837 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2839 fs_cachep
= kmem_cache_create("fs_cache",
2840 sizeof(struct fs_struct
), 0,
2841 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2845 * The mm_cpumask is located at the end of mm_struct, and is
2846 * dynamically sized based on the maximum CPU number this system
2847 * can have, taking hotplug into account (nr_cpu_ids).
2849 mm_size
= sizeof(struct mm_struct
) + cpumask_size();
2851 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
2852 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
2853 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2854 offsetof(struct mm_struct
, saved_auxv
),
2855 sizeof_field(struct mm_struct
, saved_auxv
),
2857 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2859 nsproxy_cache_init();
2863 * Check constraints on flags passed to the unshare system call.
2865 static int check_unshare_flags(unsigned long unshare_flags
)
2867 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2868 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2869 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2870 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
|
2874 * Not implemented, but pretend it works if there is nothing
2875 * to unshare. Note that unsharing the address space or the
2876 * signal handlers also need to unshare the signal queues (aka
2879 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2880 if (!thread_group_empty(current
))
2883 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2884 if (refcount_read(¤t
->sighand
->count
) > 1)
2887 if (unshare_flags
& CLONE_VM
) {
2888 if (!current_is_single_threaded())
2896 * Unshare the filesystem structure if it is being shared
2898 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2900 struct fs_struct
*fs
= current
->fs
;
2902 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2905 /* don't need lock here; in the worst case we'll do useless copy */
2909 *new_fsp
= copy_fs_struct(fs
);
2917 * Unshare file descriptor table if it is being shared
2919 int unshare_fd(unsigned long unshare_flags
, unsigned int max_fds
,
2920 struct files_struct
**new_fdp
)
2922 struct files_struct
*fd
= current
->files
;
2925 if ((unshare_flags
& CLONE_FILES
) &&
2926 (fd
&& atomic_read(&fd
->count
) > 1)) {
2927 *new_fdp
= dup_fd(fd
, max_fds
, &error
);
2936 * unshare allows a process to 'unshare' part of the process
2937 * context which was originally shared using clone. copy_*
2938 * functions used by kernel_clone() cannot be used here directly
2939 * because they modify an inactive task_struct that is being
2940 * constructed. Here we are modifying the current, active,
2943 int ksys_unshare(unsigned long unshare_flags
)
2945 struct fs_struct
*fs
, *new_fs
= NULL
;
2946 struct files_struct
*fd
, *new_fd
= NULL
;
2947 struct cred
*new_cred
= NULL
;
2948 struct nsproxy
*new_nsproxy
= NULL
;
2953 * If unsharing a user namespace must also unshare the thread group
2954 * and unshare the filesystem root and working directories.
2956 if (unshare_flags
& CLONE_NEWUSER
)
2957 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2959 * If unsharing vm, must also unshare signal handlers.
2961 if (unshare_flags
& CLONE_VM
)
2962 unshare_flags
|= CLONE_SIGHAND
;
2964 * If unsharing a signal handlers, must also unshare the signal queues.
2966 if (unshare_flags
& CLONE_SIGHAND
)
2967 unshare_flags
|= CLONE_THREAD
;
2969 * If unsharing namespace, must also unshare filesystem information.
2971 if (unshare_flags
& CLONE_NEWNS
)
2972 unshare_flags
|= CLONE_FS
;
2974 err
= check_unshare_flags(unshare_flags
);
2976 goto bad_unshare_out
;
2978 * CLONE_NEWIPC must also detach from the undolist: after switching
2979 * to a new ipc namespace, the semaphore arrays from the old
2980 * namespace are unreachable.
2982 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2984 err
= unshare_fs(unshare_flags
, &new_fs
);
2986 goto bad_unshare_out
;
2987 err
= unshare_fd(unshare_flags
, NR_OPEN_MAX
, &new_fd
);
2989 goto bad_unshare_cleanup_fs
;
2990 err
= unshare_userns(unshare_flags
, &new_cred
);
2992 goto bad_unshare_cleanup_fd
;
2993 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2996 goto bad_unshare_cleanup_cred
;
2998 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
3001 * CLONE_SYSVSEM is equivalent to sys_exit().
3005 if (unshare_flags
& CLONE_NEWIPC
) {
3006 /* Orphan segments in old ns (see sem above). */
3008 shm_init_task(current
);
3012 switch_task_namespaces(current
, new_nsproxy
);
3018 spin_lock(&fs
->lock
);
3019 current
->fs
= new_fs
;
3024 spin_unlock(&fs
->lock
);
3028 fd
= current
->files
;
3029 current
->files
= new_fd
;
3033 task_unlock(current
);
3036 /* Install the new user namespace */
3037 commit_creds(new_cred
);
3042 perf_event_namespaces(current
);
3044 bad_unshare_cleanup_cred
:
3047 bad_unshare_cleanup_fd
:
3049 put_files_struct(new_fd
);
3051 bad_unshare_cleanup_fs
:
3053 free_fs_struct(new_fs
);
3059 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
3061 return ksys_unshare(unshare_flags
);
3065 * Helper to unshare the files of the current task.
3066 * We don't want to expose copy_files internals to
3067 * the exec layer of the kernel.
3070 int unshare_files(void)
3072 struct task_struct
*task
= current
;
3073 struct files_struct
*old
, *copy
= NULL
;
3076 error
= unshare_fd(CLONE_FILES
, NR_OPEN_MAX
, ©
);
3084 put_files_struct(old
);
3088 int sysctl_max_threads(struct ctl_table
*table
, int write
,
3089 void *buffer
, size_t *lenp
, loff_t
*ppos
)
3093 int threads
= max_threads
;
3095 int max
= MAX_THREADS
;
3102 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
3106 max_threads
= threads
;