1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * 'fork.c' contains the help-routines for the 'fork' system call
10 * (see also entry.S and others).
11 * Fork is rather simple, once you get the hang of it, but the memory
12 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
15 #include <linux/anon_inodes.h>
16 #include <linux/slab.h>
17 #include <linux/sched/autogroup.h>
18 #include <linux/sched/mm.h>
19 #include <linux/sched/coredump.h>
20 #include <linux/sched/user.h>
21 #include <linux/sched/numa_balancing.h>
22 #include <linux/sched/stat.h>
23 #include <linux/sched/task.h>
24 #include <linux/sched/task_stack.h>
25 #include <linux/sched/cputime.h>
26 #include <linux/seq_file.h>
27 #include <linux/rtmutex.h>
28 #include <linux/init.h>
29 #include <linux/unistd.h>
30 #include <linux/module.h>
31 #include <linux/vmalloc.h>
32 #include <linux/completion.h>
33 #include <linux/personality.h>
34 #include <linux/mempolicy.h>
35 #include <linux/sem.h>
36 #include <linux/file.h>
37 #include <linux/fdtable.h>
38 #include <linux/iocontext.h>
39 #include <linux/key.h>
40 #include <linux/binfmts.h>
41 #include <linux/mman.h>
42 #include <linux/mmu_notifier.h>
45 #include <linux/vmacache.h>
46 #include <linux/nsproxy.h>
47 #include <linux/capability.h>
48 #include <linux/cpu.h>
49 #include <linux/cgroup.h>
50 #include <linux/security.h>
51 #include <linux/hugetlb.h>
52 #include <linux/seccomp.h>
53 #include <linux/swap.h>
54 #include <linux/syscalls.h>
55 #include <linux/jiffies.h>
56 #include <linux/futex.h>
57 #include <linux/compat.h>
58 #include <linux/kthread.h>
59 #include <linux/task_io_accounting_ops.h>
60 #include <linux/rcupdate.h>
61 #include <linux/ptrace.h>
62 #include <linux/mount.h>
63 #include <linux/audit.h>
64 #include <linux/memcontrol.h>
65 #include <linux/ftrace.h>
66 #include <linux/proc_fs.h>
67 #include <linux/profile.h>
68 #include <linux/rmap.h>
69 #include <linux/ksm.h>
70 #include <linux/acct.h>
71 #include <linux/userfaultfd_k.h>
72 #include <linux/tsacct_kern.h>
73 #include <linux/cn_proc.h>
74 #include <linux/freezer.h>
75 #include <linux/delayacct.h>
76 #include <linux/taskstats_kern.h>
77 #include <linux/random.h>
78 #include <linux/tty.h>
79 #include <linux/blkdev.h>
80 #include <linux/fs_struct.h>
81 #include <linux/magic.h>
82 #include <linux/perf_event.h>
83 #include <linux/posix-timers.h>
84 #include <linux/user-return-notifier.h>
85 #include <linux/oom.h>
86 #include <linux/khugepaged.h>
87 #include <linux/signalfd.h>
88 #include <linux/uprobes.h>
89 #include <linux/aio.h>
90 #include <linux/compiler.h>
91 #include <linux/sysctl.h>
92 #include <linux/kcov.h>
93 #include <linux/livepatch.h>
94 #include <linux/thread_info.h>
95 #include <linux/stackleak.h>
96 #include <linux/kasan.h>
97 #include <linux/scs.h>
98 #include <linux/io_uring.h>
99 #include <linux/bpf.h>
101 #include <asm/pgalloc.h>
102 #include <linux/uaccess.h>
103 #include <asm/mmu_context.h>
104 #include <asm/cacheflush.h>
105 #include <asm/tlbflush.h>
107 #include <trace/events/sched.h>
109 #define CREATE_TRACE_POINTS
110 #include <trace/events/task.h>
113 * Minimum number of threads to boot the kernel
115 #define MIN_THREADS 20
118 * Maximum number of threads
120 #define MAX_THREADS FUTEX_TID_MASK
123 * Protected counters by write_lock_irq(&tasklist_lock)
125 unsigned long total_forks
; /* Handle normal Linux uptimes. */
126 int nr_threads
; /* The idle threads do not count.. */
128 static int max_threads
; /* tunable limit on nr_threads */
130 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
132 static const char * const resident_page_types
[] = {
133 NAMED_ARRAY_INDEX(MM_FILEPAGES
),
134 NAMED_ARRAY_INDEX(MM_ANONPAGES
),
135 NAMED_ARRAY_INDEX(MM_SWAPENTS
),
136 NAMED_ARRAY_INDEX(MM_SHMEMPAGES
),
139 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
141 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
143 #ifdef CONFIG_PROVE_RCU
144 int lockdep_tasklist_lock_is_held(void)
146 return lockdep_is_held(&tasklist_lock
);
148 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
149 #endif /* #ifdef CONFIG_PROVE_RCU */
151 int nr_processes(void)
156 for_each_possible_cpu(cpu
)
157 total
+= per_cpu(process_counts
, cpu
);
162 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
166 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
167 static struct kmem_cache
*task_struct_cachep
;
169 static inline struct task_struct
*alloc_task_struct_node(int node
)
171 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
174 static inline void free_task_struct(struct task_struct
*tsk
)
176 kmem_cache_free(task_struct_cachep
, tsk
);
180 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
183 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
184 * kmemcache based allocator.
186 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
188 #ifdef CONFIG_VMAP_STACK
190 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
191 * flush. Try to minimize the number of calls by caching stacks.
193 #define NR_CACHED_STACKS 2
194 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
196 static int free_vm_stack_cache(unsigned int cpu
)
198 struct vm_struct
**cached_vm_stacks
= per_cpu_ptr(cached_stacks
, cpu
);
201 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
202 struct vm_struct
*vm_stack
= cached_vm_stacks
[i
];
207 vfree(vm_stack
->addr
);
208 cached_vm_stacks
[i
] = NULL
;
215 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
217 #ifdef CONFIG_VMAP_STACK
221 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
224 s
= this_cpu_xchg(cached_stacks
[i
], NULL
);
229 /* Mark stack accessible for KASAN. */
230 kasan_unpoison_range(s
->addr
, THREAD_SIZE
);
232 /* Clear stale pointers from reused stack. */
233 memset(s
->addr
, 0, THREAD_SIZE
);
235 tsk
->stack_vm_area
= s
;
236 tsk
->stack
= s
->addr
;
241 * Allocated stacks are cached and later reused by new threads,
242 * so memcg accounting is performed manually on assigning/releasing
243 * stacks to tasks. Drop __GFP_ACCOUNT.
245 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_ALIGN
,
246 VMALLOC_START
, VMALLOC_END
,
247 THREADINFO_GFP
& ~__GFP_ACCOUNT
,
249 0, node
, __builtin_return_address(0));
252 * We can't call find_vm_area() in interrupt context, and
253 * free_thread_stack() can be called in interrupt context,
254 * so cache the vm_struct.
257 tsk
->stack_vm_area
= find_vm_area(stack
);
262 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
266 tsk
->stack
= kasan_reset_tag(page_address(page
));
273 static inline void free_thread_stack(struct task_struct
*tsk
)
275 #ifdef CONFIG_VMAP_STACK
276 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
281 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
282 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
284 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
285 if (this_cpu_cmpxchg(cached_stacks
[i
],
286 NULL
, tsk
->stack_vm_area
) != NULL
)
292 vfree_atomic(tsk
->stack
);
297 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
300 static struct kmem_cache
*thread_stack_cache
;
302 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
305 unsigned long *stack
;
306 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
307 stack
= kasan_reset_tag(stack
);
312 static void free_thread_stack(struct task_struct
*tsk
)
314 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
317 void thread_stack_cache_init(void)
319 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
320 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
322 BUG_ON(thread_stack_cache
== NULL
);
327 /* SLAB cache for signal_struct structures (tsk->signal) */
328 static struct kmem_cache
*signal_cachep
;
330 /* SLAB cache for sighand_struct structures (tsk->sighand) */
331 struct kmem_cache
*sighand_cachep
;
333 /* SLAB cache for files_struct structures (tsk->files) */
334 struct kmem_cache
*files_cachep
;
336 /* SLAB cache for fs_struct structures (tsk->fs) */
337 struct kmem_cache
*fs_cachep
;
339 /* SLAB cache for vm_area_struct structures */
340 static struct kmem_cache
*vm_area_cachep
;
342 /* SLAB cache for mm_struct structures (tsk->mm) */
343 static struct kmem_cache
*mm_cachep
;
345 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
347 struct vm_area_struct
*vma
;
349 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
355 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
357 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
360 ASSERT_EXCLUSIVE_WRITER(orig
->vm_flags
);
361 ASSERT_EXCLUSIVE_WRITER(orig
->vm_file
);
363 * orig->shared.rb may be modified concurrently, but the clone
364 * will be reinitialized.
366 *new = data_race(*orig
);
367 INIT_LIST_HEAD(&new->anon_vma_chain
);
368 new->vm_next
= new->vm_prev
= NULL
;
373 void vm_area_free(struct vm_area_struct
*vma
)
375 kmem_cache_free(vm_area_cachep
, vma
);
378 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
380 void *stack
= task_stack_page(tsk
);
381 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
386 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
387 mod_lruvec_page_state(vm
->pages
[i
], NR_KERNEL_STACK_KB
,
388 account
* (PAGE_SIZE
/ 1024));
390 /* All stack pages are in the same node. */
391 mod_lruvec_kmem_state(stack
, NR_KERNEL_STACK_KB
,
392 account
* (THREAD_SIZE
/ 1024));
396 static int memcg_charge_kernel_stack(struct task_struct
*tsk
)
398 #ifdef CONFIG_VMAP_STACK
399 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
402 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
407 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
409 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
411 * If memcg_kmem_charge_page() fails, page's
412 * memory cgroup pointer is NULL, and
413 * memcg_kmem_uncharge_page() in free_thread_stack()
414 * will ignore this page.
416 ret
= memcg_kmem_charge_page(vm
->pages
[i
], GFP_KERNEL
,
426 static void release_task_stack(struct task_struct
*tsk
)
428 if (WARN_ON(READ_ONCE(tsk
->__state
) != TASK_DEAD
))
429 return; /* Better to leak the stack than to free prematurely */
431 account_kernel_stack(tsk
, -1);
432 free_thread_stack(tsk
);
434 #ifdef CONFIG_VMAP_STACK
435 tsk
->stack_vm_area
= NULL
;
439 #ifdef CONFIG_THREAD_INFO_IN_TASK
440 void put_task_stack(struct task_struct
*tsk
)
442 if (refcount_dec_and_test(&tsk
->stack_refcount
))
443 release_task_stack(tsk
);
447 void free_task(struct task_struct
*tsk
)
451 #ifndef CONFIG_THREAD_INFO_IN_TASK
453 * The task is finally done with both the stack and thread_info,
456 release_task_stack(tsk
);
459 * If the task had a separate stack allocation, it should be gone
462 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
464 rt_mutex_debug_task_free(tsk
);
465 ftrace_graph_exit_task(tsk
);
466 arch_release_task_struct(tsk
);
467 if (tsk
->flags
& PF_KTHREAD
)
468 free_kthread_struct(tsk
);
469 free_task_struct(tsk
);
471 EXPORT_SYMBOL(free_task
);
474 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
475 struct mm_struct
*oldmm
)
477 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
478 struct rb_node
**rb_link
, *rb_parent
;
480 unsigned long charge
;
483 uprobe_start_dup_mmap();
484 if (mmap_write_lock_killable(oldmm
)) {
486 goto fail_uprobe_end
;
488 flush_cache_dup_mm(oldmm
);
489 uprobe_dup_mmap(oldmm
, mm
);
491 * Not linked in yet - no deadlock potential:
493 mmap_write_lock_nested(mm
, SINGLE_DEPTH_NESTING
);
495 /* No ordering required: file already has been exposed. */
496 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
498 mm
->total_vm
= oldmm
->total_vm
;
499 mm
->data_vm
= oldmm
->data_vm
;
500 mm
->exec_vm
= oldmm
->exec_vm
;
501 mm
->stack_vm
= oldmm
->stack_vm
;
503 rb_link
= &mm
->mm_rb
.rb_node
;
506 retval
= ksm_fork(mm
, oldmm
);
509 retval
= khugepaged_fork(mm
, oldmm
);
514 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
517 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
518 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
523 * Don't duplicate many vmas if we've been oom-killed (for
526 if (fatal_signal_pending(current
)) {
530 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
531 unsigned long len
= vma_pages(mpnt
);
533 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
537 tmp
= vm_area_dup(mpnt
);
540 retval
= vma_dup_policy(mpnt
, tmp
);
542 goto fail_nomem_policy
;
544 retval
= dup_userfaultfd(tmp
, &uf
);
546 goto fail_nomem_anon_vma_fork
;
547 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
549 * VM_WIPEONFORK gets a clean slate in the child.
550 * Don't prepare anon_vma until fault since we don't
551 * copy page for current vma.
553 tmp
->anon_vma
= NULL
;
554 } else if (anon_vma_fork(tmp
, mpnt
))
555 goto fail_nomem_anon_vma_fork
;
556 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
559 struct inode
*inode
= file_inode(file
);
560 struct address_space
*mapping
= file
->f_mapping
;
563 if (tmp
->vm_flags
& VM_DENYWRITE
)
564 put_write_access(inode
);
565 i_mmap_lock_write(mapping
);
566 if (tmp
->vm_flags
& VM_SHARED
)
567 mapping_allow_writable(mapping
);
568 flush_dcache_mmap_lock(mapping
);
569 /* insert tmp into the share list, just after mpnt */
570 vma_interval_tree_insert_after(tmp
, mpnt
,
572 flush_dcache_mmap_unlock(mapping
);
573 i_mmap_unlock_write(mapping
);
577 * Clear hugetlb-related page reserves for children. This only
578 * affects MAP_PRIVATE mappings. Faults generated by the child
579 * are not guaranteed to succeed, even if read-only
581 if (is_vm_hugetlb_page(tmp
))
582 reset_vma_resv_huge_pages(tmp
);
585 * Link in the new vma and copy the page table entries.
588 pprev
= &tmp
->vm_next
;
592 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
593 rb_link
= &tmp
->vm_rb
.rb_right
;
594 rb_parent
= &tmp
->vm_rb
;
597 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
598 retval
= copy_page_range(tmp
, mpnt
);
600 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
601 tmp
->vm_ops
->open(tmp
);
606 /* a new mm has just been created */
607 retval
= arch_dup_mmap(oldmm
, mm
);
609 mmap_write_unlock(mm
);
611 mmap_write_unlock(oldmm
);
612 dup_userfaultfd_complete(&uf
);
614 uprobe_end_dup_mmap();
616 fail_nomem_anon_vma_fork
:
617 mpol_put(vma_policy(tmp
));
622 vm_unacct_memory(charge
);
626 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
628 mm
->pgd
= pgd_alloc(mm
);
629 if (unlikely(!mm
->pgd
))
634 static inline void mm_free_pgd(struct mm_struct
*mm
)
636 pgd_free(mm
, mm
->pgd
);
639 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
641 mmap_write_lock(oldmm
);
642 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
643 mmap_write_unlock(oldmm
);
646 #define mm_alloc_pgd(mm) (0)
647 #define mm_free_pgd(mm)
648 #endif /* CONFIG_MMU */
650 static void check_mm(struct mm_struct
*mm
)
654 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types
) != NR_MM_COUNTERS
,
655 "Please make sure 'struct resident_page_types[]' is updated as well");
657 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
658 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
661 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
662 mm
, resident_page_types
[i
], x
);
665 if (mm_pgtables_bytes(mm
))
666 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
667 mm_pgtables_bytes(mm
));
669 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
670 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
674 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
675 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
678 * Called when the last reference to the mm
679 * is dropped: either by a lazy thread or by
680 * mmput. Free the page directory and the mm.
682 void __mmdrop(struct mm_struct
*mm
)
684 BUG_ON(mm
== &init_mm
);
685 WARN_ON_ONCE(mm
== current
->mm
);
686 WARN_ON_ONCE(mm
== current
->active_mm
);
689 mmu_notifier_subscriptions_destroy(mm
);
691 put_user_ns(mm
->user_ns
);
694 EXPORT_SYMBOL_GPL(__mmdrop
);
696 static void mmdrop_async_fn(struct work_struct
*work
)
698 struct mm_struct
*mm
;
700 mm
= container_of(work
, struct mm_struct
, async_put_work
);
704 static void mmdrop_async(struct mm_struct
*mm
)
706 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
707 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
708 schedule_work(&mm
->async_put_work
);
712 static inline void free_signal_struct(struct signal_struct
*sig
)
714 taskstats_tgid_free(sig
);
715 sched_autogroup_exit(sig
);
717 * __mmdrop is not safe to call from softirq context on x86 due to
718 * pgd_dtor so postpone it to the async context
721 mmdrop_async(sig
->oom_mm
);
722 kmem_cache_free(signal_cachep
, sig
);
725 static inline void put_signal_struct(struct signal_struct
*sig
)
727 if (refcount_dec_and_test(&sig
->sigcnt
))
728 free_signal_struct(sig
);
731 void __put_task_struct(struct task_struct
*tsk
)
733 WARN_ON(!tsk
->exit_state
);
734 WARN_ON(refcount_read(&tsk
->usage
));
735 WARN_ON(tsk
== current
);
739 task_numa_free(tsk
, true);
740 security_task_free(tsk
);
741 bpf_task_storage_free(tsk
);
743 delayacct_tsk_free(tsk
);
744 put_signal_struct(tsk
->signal
);
745 sched_core_free(tsk
);
747 if (!profile_handoff_task(tsk
))
750 EXPORT_SYMBOL_GPL(__put_task_struct
);
752 void __init __weak
arch_task_cache_init(void) { }
757 static void set_max_threads(unsigned int max_threads_suggested
)
760 unsigned long nr_pages
= totalram_pages();
763 * The number of threads shall be limited such that the thread
764 * structures may only consume a small part of the available memory.
766 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
767 threads
= MAX_THREADS
;
769 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
770 (u64
) THREAD_SIZE
* 8UL);
772 if (threads
> max_threads_suggested
)
773 threads
= max_threads_suggested
;
775 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
778 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
779 /* Initialized by the architecture: */
780 int arch_task_struct_size __read_mostly
;
783 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
784 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
786 /* Fetch thread_struct whitelist for the architecture. */
787 arch_thread_struct_whitelist(offset
, size
);
790 * Handle zero-sized whitelist or empty thread_struct, otherwise
791 * adjust offset to position of thread_struct in task_struct.
793 if (unlikely(*size
== 0))
796 *offset
+= offsetof(struct task_struct
, thread
);
798 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
800 void __init
fork_init(void)
803 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
804 #ifndef ARCH_MIN_TASKALIGN
805 #define ARCH_MIN_TASKALIGN 0
807 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
808 unsigned long useroffset
, usersize
;
810 /* create a slab on which task_structs can be allocated */
811 task_struct_whitelist(&useroffset
, &usersize
);
812 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
813 arch_task_struct_size
, align
,
814 SLAB_PANIC
|SLAB_ACCOUNT
,
815 useroffset
, usersize
, NULL
);
818 /* do the arch specific task caches init */
819 arch_task_cache_init();
821 set_max_threads(MAX_THREADS
);
823 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
824 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
825 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
826 init_task
.signal
->rlim
[RLIMIT_NPROC
];
828 for (i
= 0; i
< MAX_PER_NAMESPACE_UCOUNTS
; i
++)
829 init_user_ns
.ucount_max
[i
] = max_threads
/2;
831 set_rlimit_ucount_max(&init_user_ns
, UCOUNT_RLIMIT_NPROC
, task_rlimit(&init_task
, RLIMIT_NPROC
));
832 set_rlimit_ucount_max(&init_user_ns
, UCOUNT_RLIMIT_MSGQUEUE
, task_rlimit(&init_task
, RLIMIT_MSGQUEUE
));
833 set_rlimit_ucount_max(&init_user_ns
, UCOUNT_RLIMIT_SIGPENDING
, task_rlimit(&init_task
, RLIMIT_SIGPENDING
));
834 set_rlimit_ucount_max(&init_user_ns
, UCOUNT_RLIMIT_MEMLOCK
, task_rlimit(&init_task
, RLIMIT_MEMLOCK
));
836 #ifdef CONFIG_VMAP_STACK
837 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
838 NULL
, free_vm_stack_cache
);
843 lockdep_init_task(&init_task
);
847 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
848 struct task_struct
*src
)
854 void set_task_stack_end_magic(struct task_struct
*tsk
)
856 unsigned long *stackend
;
858 stackend
= end_of_stack(tsk
);
859 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
862 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
864 struct task_struct
*tsk
;
865 unsigned long *stack
;
866 struct vm_struct
*stack_vm_area __maybe_unused
;
869 if (node
== NUMA_NO_NODE
)
870 node
= tsk_fork_get_node(orig
);
871 tsk
= alloc_task_struct_node(node
);
875 stack
= alloc_thread_stack_node(tsk
, node
);
879 if (memcg_charge_kernel_stack(tsk
))
882 stack_vm_area
= task_stack_vm_area(tsk
);
884 err
= arch_dup_task_struct(tsk
, orig
);
887 * arch_dup_task_struct() clobbers the stack-related fields. Make
888 * sure they're properly initialized before using any stack-related
892 #ifdef CONFIG_VMAP_STACK
893 tsk
->stack_vm_area
= stack_vm_area
;
895 #ifdef CONFIG_THREAD_INFO_IN_TASK
896 refcount_set(&tsk
->stack_refcount
, 1);
902 err
= scs_prepare(tsk
, node
);
906 #ifdef CONFIG_SECCOMP
908 * We must handle setting up seccomp filters once we're under
909 * the sighand lock in case orig has changed between now and
910 * then. Until then, filter must be NULL to avoid messing up
911 * the usage counts on the error path calling free_task.
913 tsk
->seccomp
.filter
= NULL
;
916 setup_thread_stack(tsk
, orig
);
917 clear_user_return_notifier(tsk
);
918 clear_tsk_need_resched(tsk
);
919 set_task_stack_end_magic(tsk
);
920 clear_syscall_work_syscall_user_dispatch(tsk
);
922 #ifdef CONFIG_STACKPROTECTOR
923 tsk
->stack_canary
= get_random_canary();
925 if (orig
->cpus_ptr
== &orig
->cpus_mask
)
926 tsk
->cpus_ptr
= &tsk
->cpus_mask
;
929 * One for the user space visible state that goes away when reaped.
930 * One for the scheduler.
932 refcount_set(&tsk
->rcu_users
, 2);
933 /* One for the rcu users */
934 refcount_set(&tsk
->usage
, 1);
935 #ifdef CONFIG_BLK_DEV_IO_TRACE
938 tsk
->splice_pipe
= NULL
;
939 tsk
->task_frag
.page
= NULL
;
940 tsk
->wake_q
.next
= NULL
;
941 tsk
->pf_io_worker
= NULL
;
943 account_kernel_stack(tsk
, 1);
946 kmap_local_fork(tsk
);
948 #ifdef CONFIG_FAULT_INJECTION
952 #ifdef CONFIG_BLK_CGROUP
953 tsk
->throttle_queue
= NULL
;
954 tsk
->use_memdelay
= 0;
958 tsk
->active_memcg
= NULL
;
963 free_thread_stack(tsk
);
965 free_task_struct(tsk
);
969 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
971 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
973 static int __init
coredump_filter_setup(char *s
)
975 default_dump_filter
=
976 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
977 MMF_DUMP_FILTER_MASK
;
981 __setup("coredump_filter=", coredump_filter_setup
);
983 #include <linux/init_task.h>
985 static void mm_init_aio(struct mm_struct
*mm
)
988 spin_lock_init(&mm
->ioctx_lock
);
989 mm
->ioctx_table
= NULL
;
993 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
994 struct task_struct
*p
)
998 WRITE_ONCE(mm
->owner
, NULL
);
1002 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1009 static void mm_init_pasid(struct mm_struct
*mm
)
1011 #ifdef CONFIG_IOMMU_SUPPORT
1012 mm
->pasid
= INIT_PASID
;
1016 static void mm_init_uprobes_state(struct mm_struct
*mm
)
1018 #ifdef CONFIG_UPROBES
1019 mm
->uprobes_state
.xol_area
= NULL
;
1023 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
1024 struct user_namespace
*user_ns
)
1027 mm
->mm_rb
= RB_ROOT
;
1028 mm
->vmacache_seqnum
= 0;
1029 atomic_set(&mm
->mm_users
, 1);
1030 atomic_set(&mm
->mm_count
, 1);
1031 seqcount_init(&mm
->write_protect_seq
);
1033 INIT_LIST_HEAD(&mm
->mmlist
);
1034 mm
->core_state
= NULL
;
1035 mm_pgtables_bytes_init(mm
);
1038 atomic64_set(&mm
->pinned_vm
, 0);
1039 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
1040 spin_lock_init(&mm
->page_table_lock
);
1041 spin_lock_init(&mm
->arg_lock
);
1042 mm_init_cpumask(mm
);
1044 mm_init_owner(mm
, p
);
1046 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1047 mmu_notifier_subscriptions_init(mm
);
1048 init_tlb_flush_pending(mm
);
1049 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1050 mm
->pmd_huge_pte
= NULL
;
1052 mm_init_uprobes_state(mm
);
1055 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1056 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1058 mm
->flags
= default_dump_filter
;
1062 if (mm_alloc_pgd(mm
))
1065 if (init_new_context(p
, mm
))
1066 goto fail_nocontext
;
1068 mm
->user_ns
= get_user_ns(user_ns
);
1079 * Allocate and initialize an mm_struct.
1081 struct mm_struct
*mm_alloc(void)
1083 struct mm_struct
*mm
;
1089 memset(mm
, 0, sizeof(*mm
));
1090 return mm_init(mm
, current
, current_user_ns());
1093 static inline void __mmput(struct mm_struct
*mm
)
1095 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1097 uprobe_clear_state(mm
);
1100 khugepaged_exit(mm
); /* must run before exit_mmap */
1102 mm_put_huge_zero_page(mm
);
1103 set_mm_exe_file(mm
, NULL
);
1104 if (!list_empty(&mm
->mmlist
)) {
1105 spin_lock(&mmlist_lock
);
1106 list_del(&mm
->mmlist
);
1107 spin_unlock(&mmlist_lock
);
1110 module_put(mm
->binfmt
->module
);
1115 * Decrement the use count and release all resources for an mm.
1117 void mmput(struct mm_struct
*mm
)
1121 if (atomic_dec_and_test(&mm
->mm_users
))
1124 EXPORT_SYMBOL_GPL(mmput
);
1127 static void mmput_async_fn(struct work_struct
*work
)
1129 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1135 void mmput_async(struct mm_struct
*mm
)
1137 if (atomic_dec_and_test(&mm
->mm_users
)) {
1138 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1139 schedule_work(&mm
->async_put_work
);
1145 * set_mm_exe_file - change a reference to the mm's executable file
1147 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1149 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1150 * invocations: in mmput() nobody alive left, in execve task is single
1151 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1152 * mm->exe_file, but does so without using set_mm_exe_file() in order
1153 * to avoid the need for any locks.
1155 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1157 struct file
*old_exe_file
;
1160 * It is safe to dereference the exe_file without RCU as
1161 * this function is only called if nobody else can access
1162 * this mm -- see comment above for justification.
1164 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1167 get_file(new_exe_file
);
1168 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1174 * get_mm_exe_file - acquire a reference to the mm's executable file
1176 * Returns %NULL if mm has no associated executable file.
1177 * User must release file via fput().
1179 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1181 struct file
*exe_file
;
1184 exe_file
= rcu_dereference(mm
->exe_file
);
1185 if (exe_file
&& !get_file_rcu(exe_file
))
1190 EXPORT_SYMBOL(get_mm_exe_file
);
1193 * get_task_exe_file - acquire a reference to the task's executable file
1195 * Returns %NULL if task's mm (if any) has no associated executable file or
1196 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1197 * User must release file via fput().
1199 struct file
*get_task_exe_file(struct task_struct
*task
)
1201 struct file
*exe_file
= NULL
;
1202 struct mm_struct
*mm
;
1207 if (!(task
->flags
& PF_KTHREAD
))
1208 exe_file
= get_mm_exe_file(mm
);
1213 EXPORT_SYMBOL(get_task_exe_file
);
1216 * get_task_mm - acquire a reference to the task's mm
1218 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1219 * this kernel workthread has transiently adopted a user mm with use_mm,
1220 * to do its AIO) is not set and if so returns a reference to it, after
1221 * bumping up the use count. User must release the mm via mmput()
1222 * after use. Typically used by /proc and ptrace.
1224 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1226 struct mm_struct
*mm
;
1231 if (task
->flags
& PF_KTHREAD
)
1239 EXPORT_SYMBOL_GPL(get_task_mm
);
1241 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1243 struct mm_struct
*mm
;
1246 err
= down_read_killable(&task
->signal
->exec_update_lock
);
1248 return ERR_PTR(err
);
1250 mm
= get_task_mm(task
);
1251 if (mm
&& mm
!= current
->mm
&&
1252 !ptrace_may_access(task
, mode
)) {
1254 mm
= ERR_PTR(-EACCES
);
1256 up_read(&task
->signal
->exec_update_lock
);
1261 static void complete_vfork_done(struct task_struct
*tsk
)
1263 struct completion
*vfork
;
1266 vfork
= tsk
->vfork_done
;
1267 if (likely(vfork
)) {
1268 tsk
->vfork_done
= NULL
;
1274 static int wait_for_vfork_done(struct task_struct
*child
,
1275 struct completion
*vfork
)
1279 freezer_do_not_count();
1280 cgroup_enter_frozen();
1281 killed
= wait_for_completion_killable(vfork
);
1282 cgroup_leave_frozen(false);
1287 child
->vfork_done
= NULL
;
1291 put_task_struct(child
);
1295 /* Please note the differences between mmput and mm_release.
1296 * mmput is called whenever we stop holding onto a mm_struct,
1297 * error success whatever.
1299 * mm_release is called after a mm_struct has been removed
1300 * from the current process.
1302 * This difference is important for error handling, when we
1303 * only half set up a mm_struct for a new process and need to restore
1304 * the old one. Because we mmput the new mm_struct before
1305 * restoring the old one. . .
1306 * Eric Biederman 10 January 1998
1308 static void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1310 uprobe_free_utask(tsk
);
1312 /* Get rid of any cached register state */
1313 deactivate_mm(tsk
, mm
);
1316 * Signal userspace if we're not exiting with a core dump
1317 * because we want to leave the value intact for debugging
1320 if (tsk
->clear_child_tid
) {
1321 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1322 atomic_read(&mm
->mm_users
) > 1) {
1324 * We don't check the error code - if userspace has
1325 * not set up a proper pointer then tough luck.
1327 put_user(0, tsk
->clear_child_tid
);
1328 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1329 1, NULL
, NULL
, 0, 0);
1331 tsk
->clear_child_tid
= NULL
;
1335 * All done, finally we can wake up parent and return this mm to him.
1336 * Also kthread_stop() uses this completion for synchronization.
1338 if (tsk
->vfork_done
)
1339 complete_vfork_done(tsk
);
1342 void exit_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1344 futex_exit_release(tsk
);
1345 mm_release(tsk
, mm
);
1348 void exec_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1350 futex_exec_release(tsk
);
1351 mm_release(tsk
, mm
);
1355 * dup_mm() - duplicates an existing mm structure
1356 * @tsk: the task_struct with which the new mm will be associated.
1357 * @oldmm: the mm to duplicate.
1359 * Allocates a new mm structure and duplicates the provided @oldmm structure
1362 * Return: the duplicated mm or NULL on failure.
1364 static struct mm_struct
*dup_mm(struct task_struct
*tsk
,
1365 struct mm_struct
*oldmm
)
1367 struct mm_struct
*mm
;
1374 memcpy(mm
, oldmm
, sizeof(*mm
));
1376 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1379 err
= dup_mmap(mm
, oldmm
);
1383 mm
->hiwater_rss
= get_mm_rss(mm
);
1384 mm
->hiwater_vm
= mm
->total_vm
;
1386 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1392 /* don't put binfmt in mmput, we haven't got module yet */
1394 mm_init_owner(mm
, NULL
);
1401 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1403 struct mm_struct
*mm
, *oldmm
;
1405 tsk
->min_flt
= tsk
->maj_flt
= 0;
1406 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1407 #ifdef CONFIG_DETECT_HUNG_TASK
1408 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1409 tsk
->last_switch_time
= 0;
1413 tsk
->active_mm
= NULL
;
1416 * Are we cloning a kernel thread?
1418 * We need to steal a active VM for that..
1420 oldmm
= current
->mm
;
1424 /* initialize the new vmacache entries */
1425 vmacache_flush(tsk
);
1427 if (clone_flags
& CLONE_VM
) {
1431 mm
= dup_mm(tsk
, current
->mm
);
1437 tsk
->active_mm
= mm
;
1441 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1443 struct fs_struct
*fs
= current
->fs
;
1444 if (clone_flags
& CLONE_FS
) {
1445 /* tsk->fs is already what we want */
1446 spin_lock(&fs
->lock
);
1448 spin_unlock(&fs
->lock
);
1452 spin_unlock(&fs
->lock
);
1455 tsk
->fs
= copy_fs_struct(fs
);
1461 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1463 struct files_struct
*oldf
, *newf
;
1467 * A background process may not have any files ...
1469 oldf
= current
->files
;
1473 if (clone_flags
& CLONE_FILES
) {
1474 atomic_inc(&oldf
->count
);
1478 newf
= dup_fd(oldf
, NR_OPEN_MAX
, &error
);
1488 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1491 struct io_context
*ioc
= current
->io_context
;
1492 struct io_context
*new_ioc
;
1497 * Share io context with parent, if CLONE_IO is set
1499 if (clone_flags
& CLONE_IO
) {
1501 tsk
->io_context
= ioc
;
1502 } else if (ioprio_valid(ioc
->ioprio
)) {
1503 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1504 if (unlikely(!new_ioc
))
1507 new_ioc
->ioprio
= ioc
->ioprio
;
1508 put_io_context(new_ioc
);
1514 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1516 struct sighand_struct
*sig
;
1518 if (clone_flags
& CLONE_SIGHAND
) {
1519 refcount_inc(¤t
->sighand
->count
);
1522 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1523 RCU_INIT_POINTER(tsk
->sighand
, sig
);
1527 refcount_set(&sig
->count
, 1);
1528 spin_lock_irq(¤t
->sighand
->siglock
);
1529 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1530 spin_unlock_irq(¤t
->sighand
->siglock
);
1532 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1533 if (clone_flags
& CLONE_CLEAR_SIGHAND
)
1534 flush_signal_handlers(tsk
, 0);
1539 void __cleanup_sighand(struct sighand_struct
*sighand
)
1541 if (refcount_dec_and_test(&sighand
->count
)) {
1542 signalfd_cleanup(sighand
);
1544 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1545 * without an RCU grace period, see __lock_task_sighand().
1547 kmem_cache_free(sighand_cachep
, sighand
);
1552 * Initialize POSIX timer handling for a thread group.
1554 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1556 struct posix_cputimers
*pct
= &sig
->posix_cputimers
;
1557 unsigned long cpu_limit
;
1559 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1560 posix_cputimers_group_init(pct
, cpu_limit
);
1563 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1565 struct signal_struct
*sig
;
1567 if (clone_flags
& CLONE_THREAD
)
1570 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1575 sig
->nr_threads
= 1;
1576 atomic_set(&sig
->live
, 1);
1577 refcount_set(&sig
->sigcnt
, 1);
1579 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1580 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1581 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1583 init_waitqueue_head(&sig
->wait_chldexit
);
1584 sig
->curr_target
= tsk
;
1585 init_sigpending(&sig
->shared_pending
);
1586 INIT_HLIST_HEAD(&sig
->multiprocess
);
1587 seqlock_init(&sig
->stats_lock
);
1588 prev_cputime_init(&sig
->prev_cputime
);
1590 #ifdef CONFIG_POSIX_TIMERS
1591 INIT_LIST_HEAD(&sig
->posix_timers
);
1592 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1593 sig
->real_timer
.function
= it_real_fn
;
1596 task_lock(current
->group_leader
);
1597 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1598 task_unlock(current
->group_leader
);
1600 posix_cpu_timers_init_group(sig
);
1602 tty_audit_fork(sig
);
1603 sched_autogroup_fork(sig
);
1605 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1606 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1608 mutex_init(&sig
->cred_guard_mutex
);
1609 init_rwsem(&sig
->exec_update_lock
);
1614 static void copy_seccomp(struct task_struct
*p
)
1616 #ifdef CONFIG_SECCOMP
1618 * Must be called with sighand->lock held, which is common to
1619 * all threads in the group. Holding cred_guard_mutex is not
1620 * needed because this new task is not yet running and cannot
1623 assert_spin_locked(¤t
->sighand
->siglock
);
1625 /* Ref-count the new filter user, and assign it. */
1626 get_seccomp_filter(current
);
1627 p
->seccomp
= current
->seccomp
;
1630 * Explicitly enable no_new_privs here in case it got set
1631 * between the task_struct being duplicated and holding the
1632 * sighand lock. The seccomp state and nnp must be in sync.
1634 if (task_no_new_privs(current
))
1635 task_set_no_new_privs(p
);
1638 * If the parent gained a seccomp mode after copying thread
1639 * flags and between before we held the sighand lock, we have
1640 * to manually enable the seccomp thread flag here.
1642 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1643 set_task_syscall_work(p
, SECCOMP
);
1647 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1649 current
->clear_child_tid
= tidptr
;
1651 return task_pid_vnr(current
);
1654 static void rt_mutex_init_task(struct task_struct
*p
)
1656 raw_spin_lock_init(&p
->pi_lock
);
1657 #ifdef CONFIG_RT_MUTEXES
1658 p
->pi_waiters
= RB_ROOT_CACHED
;
1659 p
->pi_top_task
= NULL
;
1660 p
->pi_blocked_on
= NULL
;
1664 static inline void init_task_pid_links(struct task_struct
*task
)
1668 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
)
1669 INIT_HLIST_NODE(&task
->pid_links
[type
]);
1673 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1675 if (type
== PIDTYPE_PID
)
1676 task
->thread_pid
= pid
;
1678 task
->signal
->pids
[type
] = pid
;
1681 static inline void rcu_copy_process(struct task_struct
*p
)
1683 #ifdef CONFIG_PREEMPT_RCU
1684 p
->rcu_read_lock_nesting
= 0;
1685 p
->rcu_read_unlock_special
.s
= 0;
1686 p
->rcu_blocked_node
= NULL
;
1687 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1688 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1689 #ifdef CONFIG_TASKS_RCU
1690 p
->rcu_tasks_holdout
= false;
1691 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1692 p
->rcu_tasks_idle_cpu
= -1;
1693 #endif /* #ifdef CONFIG_TASKS_RCU */
1694 #ifdef CONFIG_TASKS_TRACE_RCU
1695 p
->trc_reader_nesting
= 0;
1696 p
->trc_reader_special
.s
= 0;
1697 INIT_LIST_HEAD(&p
->trc_holdout_list
);
1698 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1701 struct pid
*pidfd_pid(const struct file
*file
)
1703 if (file
->f_op
== &pidfd_fops
)
1704 return file
->private_data
;
1706 return ERR_PTR(-EBADF
);
1709 static int pidfd_release(struct inode
*inode
, struct file
*file
)
1711 struct pid
*pid
= file
->private_data
;
1713 file
->private_data
= NULL
;
1718 #ifdef CONFIG_PROC_FS
1720 * pidfd_show_fdinfo - print information about a pidfd
1721 * @m: proc fdinfo file
1722 * @f: file referencing a pidfd
1725 * This function will print the pid that a given pidfd refers to in the
1726 * pid namespace of the procfs instance.
1727 * If the pid namespace of the process is not a descendant of the pid
1728 * namespace of the procfs instance 0 will be shown as its pid. This is
1729 * similar to calling getppid() on a process whose parent is outside of
1730 * its pid namespace.
1733 * If pid namespaces are supported then this function will also print
1734 * the pid of a given pidfd refers to for all descendant pid namespaces
1735 * starting from the current pid namespace of the instance, i.e. the
1736 * Pid field and the first entry in the NSpid field will be identical.
1737 * If the pid namespace of the process is not a descendant of the pid
1738 * namespace of the procfs instance 0 will be shown as its first NSpid
1739 * entry and no others will be shown.
1740 * Note that this differs from the Pid and NSpid fields in
1741 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1742 * the pid namespace of the procfs instance. The difference becomes
1743 * obvious when sending around a pidfd between pid namespaces from a
1744 * different branch of the tree, i.e. where no ancestral relation is
1745 * present between the pid namespaces:
1746 * - create two new pid namespaces ns1 and ns2 in the initial pid
1747 * namespace (also take care to create new mount namespaces in the
1748 * new pid namespace and mount procfs)
1749 * - create a process with a pidfd in ns1
1750 * - send pidfd from ns1 to ns2
1751 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1752 * have exactly one entry, which is 0
1754 static void pidfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
1756 struct pid
*pid
= f
->private_data
;
1757 struct pid_namespace
*ns
;
1760 if (likely(pid_has_task(pid
, PIDTYPE_PID
))) {
1761 ns
= proc_pid_ns(file_inode(m
->file
)->i_sb
);
1762 nr
= pid_nr_ns(pid
, ns
);
1765 seq_put_decimal_ll(m
, "Pid:\t", nr
);
1767 #ifdef CONFIG_PID_NS
1768 seq_put_decimal_ll(m
, "\nNSpid:\t", nr
);
1772 /* If nr is non-zero it means that 'pid' is valid and that
1773 * ns, i.e. the pid namespace associated with the procfs
1774 * instance, is in the pid namespace hierarchy of pid.
1775 * Start at one below the already printed level.
1777 for (i
= ns
->level
+ 1; i
<= pid
->level
; i
++)
1778 seq_put_decimal_ll(m
, "\t", pid
->numbers
[i
].nr
);
1786 * Poll support for process exit notification.
1788 static __poll_t
pidfd_poll(struct file
*file
, struct poll_table_struct
*pts
)
1790 struct pid
*pid
= file
->private_data
;
1791 __poll_t poll_flags
= 0;
1793 poll_wait(file
, &pid
->wait_pidfd
, pts
);
1796 * Inform pollers only when the whole thread group exits.
1797 * If the thread group leader exits before all other threads in the
1798 * group, then poll(2) should block, similar to the wait(2) family.
1800 if (thread_group_exited(pid
))
1801 poll_flags
= EPOLLIN
| EPOLLRDNORM
;
1806 const struct file_operations pidfd_fops
= {
1807 .release
= pidfd_release
,
1809 #ifdef CONFIG_PROC_FS
1810 .show_fdinfo
= pidfd_show_fdinfo
,
1814 static void __delayed_free_task(struct rcu_head
*rhp
)
1816 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
1821 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
1823 if (IS_ENABLED(CONFIG_MEMCG
))
1824 call_rcu(&tsk
->rcu
, __delayed_free_task
);
1829 static void copy_oom_score_adj(u64 clone_flags
, struct task_struct
*tsk
)
1831 /* Skip if kernel thread */
1835 /* Skip if spawning a thread or using vfork */
1836 if ((clone_flags
& (CLONE_VM
| CLONE_THREAD
| CLONE_VFORK
)) != CLONE_VM
)
1839 /* We need to synchronize with __set_oom_adj */
1840 mutex_lock(&oom_adj_mutex
);
1841 set_bit(MMF_MULTIPROCESS
, &tsk
->mm
->flags
);
1842 /* Update the values in case they were changed after copy_signal */
1843 tsk
->signal
->oom_score_adj
= current
->signal
->oom_score_adj
;
1844 tsk
->signal
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1845 mutex_unlock(&oom_adj_mutex
);
1849 * This creates a new process as a copy of the old one,
1850 * but does not actually start it yet.
1852 * It copies the registers, and all the appropriate
1853 * parts of the process environment (as per the clone
1854 * flags). The actual kick-off is left to the caller.
1856 static __latent_entropy
struct task_struct
*copy_process(
1860 struct kernel_clone_args
*args
)
1862 int pidfd
= -1, retval
;
1863 struct task_struct
*p
;
1864 struct multiprocess_signals delayed
;
1865 struct file
*pidfile
= NULL
;
1866 u64 clone_flags
= args
->flags
;
1867 struct nsproxy
*nsp
= current
->nsproxy
;
1870 * Don't allow sharing the root directory with processes in a different
1873 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1874 return ERR_PTR(-EINVAL
);
1876 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1877 return ERR_PTR(-EINVAL
);
1880 * Thread groups must share signals as well, and detached threads
1881 * can only be started up within the thread group.
1883 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1884 return ERR_PTR(-EINVAL
);
1887 * Shared signal handlers imply shared VM. By way of the above,
1888 * thread groups also imply shared VM. Blocking this case allows
1889 * for various simplifications in other code.
1891 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1892 return ERR_PTR(-EINVAL
);
1895 * Siblings of global init remain as zombies on exit since they are
1896 * not reaped by their parent (swapper). To solve this and to avoid
1897 * multi-rooted process trees, prevent global and container-inits
1898 * from creating siblings.
1900 if ((clone_flags
& CLONE_PARENT
) &&
1901 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1902 return ERR_PTR(-EINVAL
);
1905 * If the new process will be in a different pid or user namespace
1906 * do not allow it to share a thread group with the forking task.
1908 if (clone_flags
& CLONE_THREAD
) {
1909 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1910 (task_active_pid_ns(current
) != nsp
->pid_ns_for_children
))
1911 return ERR_PTR(-EINVAL
);
1915 * If the new process will be in a different time namespace
1916 * do not allow it to share VM or a thread group with the forking task.
1918 if (clone_flags
& (CLONE_THREAD
| CLONE_VM
)) {
1919 if (nsp
->time_ns
!= nsp
->time_ns_for_children
)
1920 return ERR_PTR(-EINVAL
);
1923 if (clone_flags
& CLONE_PIDFD
) {
1925 * - CLONE_DETACHED is blocked so that we can potentially
1926 * reuse it later for CLONE_PIDFD.
1927 * - CLONE_THREAD is blocked until someone really needs it.
1929 if (clone_flags
& (CLONE_DETACHED
| CLONE_THREAD
))
1930 return ERR_PTR(-EINVAL
);
1934 * Force any signals received before this point to be delivered
1935 * before the fork happens. Collect up signals sent to multiple
1936 * processes that happen during the fork and delay them so that
1937 * they appear to happen after the fork.
1939 sigemptyset(&delayed
.signal
);
1940 INIT_HLIST_NODE(&delayed
.node
);
1942 spin_lock_irq(¤t
->sighand
->siglock
);
1943 if (!(clone_flags
& CLONE_THREAD
))
1944 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
1945 recalc_sigpending();
1946 spin_unlock_irq(¤t
->sighand
->siglock
);
1947 retval
= -ERESTARTNOINTR
;
1948 if (task_sigpending(current
))
1952 p
= dup_task_struct(current
, node
);
1955 if (args
->io_thread
) {
1957 * Mark us an IO worker, and block any signal that isn't
1960 p
->flags
|= PF_IO_WORKER
;
1961 siginitsetinv(&p
->blocked
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
1965 * This _must_ happen before we call free_task(), i.e. before we jump
1966 * to any of the bad_fork_* labels. This is to avoid freeing
1967 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1968 * kernel threads (PF_KTHREAD).
1970 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? args
->child_tid
: NULL
;
1972 * Clear TID on mm_release()?
1974 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? args
->child_tid
: NULL
;
1976 ftrace_graph_init_task(p
);
1978 rt_mutex_init_task(p
);
1980 lockdep_assert_irqs_enabled();
1981 #ifdef CONFIG_PROVE_LOCKING
1982 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1985 if (is_ucounts_overlimit(task_ucounts(p
), UCOUNT_RLIMIT_NPROC
, rlimit(RLIMIT_NPROC
))) {
1986 if (p
->real_cred
->user
!= INIT_USER
&&
1987 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1990 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1992 retval
= copy_creds(p
, clone_flags
);
1997 * If multiple threads are within copy_process(), then this check
1998 * triggers too late. This doesn't hurt, the check is only there
1999 * to stop root fork bombs.
2002 if (data_race(nr_threads
>= max_threads
))
2003 goto bad_fork_cleanup_count
;
2005 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
2006 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
| PF_NO_SETAFFINITY
);
2007 p
->flags
|= PF_FORKNOEXEC
;
2008 INIT_LIST_HEAD(&p
->children
);
2009 INIT_LIST_HEAD(&p
->sibling
);
2010 rcu_copy_process(p
);
2011 p
->vfork_done
= NULL
;
2012 spin_lock_init(&p
->alloc_lock
);
2014 init_sigpending(&p
->pending
);
2016 p
->utime
= p
->stime
= p
->gtime
= 0;
2017 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2018 p
->utimescaled
= p
->stimescaled
= 0;
2020 prev_cputime_init(&p
->prev_cputime
);
2022 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2023 seqcount_init(&p
->vtime
.seqcount
);
2024 p
->vtime
.starttime
= 0;
2025 p
->vtime
.state
= VTIME_INACTIVE
;
2028 #ifdef CONFIG_IO_URING
2032 #if defined(SPLIT_RSS_COUNTING)
2033 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
2036 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
2042 task_io_accounting_init(&p
->ioac
);
2043 acct_clear_integrals(p
);
2045 posix_cputimers_init(&p
->posix_cputimers
);
2047 p
->io_context
= NULL
;
2048 audit_set_context(p
, NULL
);
2051 p
->mempolicy
= mpol_dup(p
->mempolicy
);
2052 if (IS_ERR(p
->mempolicy
)) {
2053 retval
= PTR_ERR(p
->mempolicy
);
2054 p
->mempolicy
= NULL
;
2055 goto bad_fork_cleanup_threadgroup_lock
;
2058 #ifdef CONFIG_CPUSETS
2059 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
2060 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
2061 seqcount_spinlock_init(&p
->mems_allowed_seq
, &p
->alloc_lock
);
2063 #ifdef CONFIG_TRACE_IRQFLAGS
2064 memset(&p
->irqtrace
, 0, sizeof(p
->irqtrace
));
2065 p
->irqtrace
.hardirq_disable_ip
= _THIS_IP_
;
2066 p
->irqtrace
.softirq_enable_ip
= _THIS_IP_
;
2067 p
->softirqs_enabled
= 1;
2068 p
->softirq_context
= 0;
2071 p
->pagefault_disabled
= 0;
2073 #ifdef CONFIG_LOCKDEP
2074 lockdep_init_task(p
);
2077 #ifdef CONFIG_DEBUG_MUTEXES
2078 p
->blocked_on
= NULL
; /* not blocked yet */
2080 #ifdef CONFIG_BCACHE
2081 p
->sequential_io
= 0;
2082 p
->sequential_io_avg
= 0;
2084 #ifdef CONFIG_BPF_SYSCALL
2085 RCU_INIT_POINTER(p
->bpf_storage
, NULL
);
2088 /* Perform scheduler related setup. Assign this task to a CPU. */
2089 retval
= sched_fork(clone_flags
, p
);
2091 goto bad_fork_cleanup_policy
;
2093 retval
= perf_event_init_task(p
, clone_flags
);
2095 goto bad_fork_cleanup_policy
;
2096 retval
= audit_alloc(p
);
2098 goto bad_fork_cleanup_perf
;
2099 /* copy all the process information */
2101 retval
= security_task_alloc(p
, clone_flags
);
2103 goto bad_fork_cleanup_audit
;
2104 retval
= copy_semundo(clone_flags
, p
);
2106 goto bad_fork_cleanup_security
;
2107 retval
= copy_files(clone_flags
, p
);
2109 goto bad_fork_cleanup_semundo
;
2110 retval
= copy_fs(clone_flags
, p
);
2112 goto bad_fork_cleanup_files
;
2113 retval
= copy_sighand(clone_flags
, p
);
2115 goto bad_fork_cleanup_fs
;
2116 retval
= copy_signal(clone_flags
, p
);
2118 goto bad_fork_cleanup_sighand
;
2119 retval
= copy_mm(clone_flags
, p
);
2121 goto bad_fork_cleanup_signal
;
2122 retval
= copy_namespaces(clone_flags
, p
);
2124 goto bad_fork_cleanup_mm
;
2125 retval
= copy_io(clone_flags
, p
);
2127 goto bad_fork_cleanup_namespaces
;
2128 retval
= copy_thread(clone_flags
, args
->stack
, args
->stack_size
, p
, args
->tls
);
2130 goto bad_fork_cleanup_io
;
2132 stackleak_task_init(p
);
2134 if (pid
!= &init_struct_pid
) {
2135 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
, args
->set_tid
,
2136 args
->set_tid_size
);
2138 retval
= PTR_ERR(pid
);
2139 goto bad_fork_cleanup_thread
;
2144 * This has to happen after we've potentially unshared the file
2145 * descriptor table (so that the pidfd doesn't leak into the child
2146 * if the fd table isn't shared).
2148 if (clone_flags
& CLONE_PIDFD
) {
2149 retval
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2151 goto bad_fork_free_pid
;
2155 pidfile
= anon_inode_getfile("[pidfd]", &pidfd_fops
, pid
,
2156 O_RDWR
| O_CLOEXEC
);
2157 if (IS_ERR(pidfile
)) {
2158 put_unused_fd(pidfd
);
2159 retval
= PTR_ERR(pidfile
);
2160 goto bad_fork_free_pid
;
2162 get_pid(pid
); /* held by pidfile now */
2164 retval
= put_user(pidfd
, args
->pidfd
);
2166 goto bad_fork_put_pidfd
;
2175 * sigaltstack should be cleared when sharing the same VM
2177 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
2181 * Syscall tracing and stepping should be turned off in the
2182 * child regardless of CLONE_PTRACE.
2184 user_disable_single_step(p
);
2185 clear_task_syscall_work(p
, SYSCALL_TRACE
);
2186 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2187 clear_task_syscall_work(p
, SYSCALL_EMU
);
2189 clear_tsk_latency_tracing(p
);
2191 /* ok, now we should be set up.. */
2192 p
->pid
= pid_nr(pid
);
2193 if (clone_flags
& CLONE_THREAD
) {
2194 p
->group_leader
= current
->group_leader
;
2195 p
->tgid
= current
->tgid
;
2197 p
->group_leader
= p
;
2202 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2203 p
->dirty_paused_when
= 0;
2205 p
->pdeath_signal
= 0;
2206 INIT_LIST_HEAD(&p
->thread_group
);
2207 p
->task_works
= NULL
;
2209 #ifdef CONFIG_KRETPROBES
2210 p
->kretprobe_instances
.first
= NULL
;
2214 * Ensure that the cgroup subsystem policies allow the new process to be
2215 * forked. It should be noted that the new process's css_set can be changed
2216 * between here and cgroup_post_fork() if an organisation operation is in
2219 retval
= cgroup_can_fork(p
, args
);
2221 goto bad_fork_put_pidfd
;
2224 * From this point on we must avoid any synchronous user-space
2225 * communication until we take the tasklist-lock. In particular, we do
2226 * not want user-space to be able to predict the process start-time by
2227 * stalling fork(2) after we recorded the start_time but before it is
2228 * visible to the system.
2231 p
->start_time
= ktime_get_ns();
2232 p
->start_boottime
= ktime_get_boottime_ns();
2235 * Make it visible to the rest of the system, but dont wake it up yet.
2236 * Need tasklist lock for parent etc handling!
2238 write_lock_irq(&tasklist_lock
);
2240 /* CLONE_PARENT re-uses the old parent */
2241 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2242 p
->real_parent
= current
->real_parent
;
2243 p
->parent_exec_id
= current
->parent_exec_id
;
2244 if (clone_flags
& CLONE_THREAD
)
2245 p
->exit_signal
= -1;
2247 p
->exit_signal
= current
->group_leader
->exit_signal
;
2249 p
->real_parent
= current
;
2250 p
->parent_exec_id
= current
->self_exec_id
;
2251 p
->exit_signal
= args
->exit_signal
;
2254 klp_copy_process(p
);
2258 spin_lock(¤t
->sighand
->siglock
);
2261 * Copy seccomp details explicitly here, in case they were changed
2262 * before holding sighand lock.
2266 rseq_fork(p
, clone_flags
);
2268 /* Don't start children in a dying pid namespace */
2269 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2271 goto bad_fork_cancel_cgroup
;
2274 /* Let kill terminate clone/fork in the middle */
2275 if (fatal_signal_pending(current
)) {
2277 goto bad_fork_cancel_cgroup
;
2280 /* past the last point of failure */
2282 fd_install(pidfd
, pidfile
);
2284 init_task_pid_links(p
);
2285 if (likely(p
->pid
)) {
2286 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2288 init_task_pid(p
, PIDTYPE_PID
, pid
);
2289 if (thread_group_leader(p
)) {
2290 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2291 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2292 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2294 if (is_child_reaper(pid
)) {
2295 ns_of_pid(pid
)->child_reaper
= p
;
2296 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2298 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2299 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2301 * Inherit has_child_subreaper flag under the same
2302 * tasklist_lock with adding child to the process tree
2303 * for propagate_has_child_subreaper optimization.
2305 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2306 p
->real_parent
->signal
->is_child_subreaper
;
2307 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2308 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2309 attach_pid(p
, PIDTYPE_TGID
);
2310 attach_pid(p
, PIDTYPE_PGID
);
2311 attach_pid(p
, PIDTYPE_SID
);
2312 __this_cpu_inc(process_counts
);
2314 current
->signal
->nr_threads
++;
2315 atomic_inc(¤t
->signal
->live
);
2316 refcount_inc(¤t
->signal
->sigcnt
);
2317 task_join_group_stop(p
);
2318 list_add_tail_rcu(&p
->thread_group
,
2319 &p
->group_leader
->thread_group
);
2320 list_add_tail_rcu(&p
->thread_node
,
2321 &p
->signal
->thread_head
);
2323 attach_pid(p
, PIDTYPE_PID
);
2327 hlist_del_init(&delayed
.node
);
2328 spin_unlock(¤t
->sighand
->siglock
);
2329 syscall_tracepoint_update(p
);
2330 write_unlock_irq(&tasklist_lock
);
2332 proc_fork_connector(p
);
2334 cgroup_post_fork(p
, args
);
2337 trace_task_newtask(p
, clone_flags
);
2338 uprobe_copy_process(p
, clone_flags
);
2340 copy_oom_score_adj(clone_flags
, p
);
2344 bad_fork_cancel_cgroup
:
2346 spin_unlock(¤t
->sighand
->siglock
);
2347 write_unlock_irq(&tasklist_lock
);
2348 cgroup_cancel_fork(p
, args
);
2350 if (clone_flags
& CLONE_PIDFD
) {
2352 put_unused_fd(pidfd
);
2355 if (pid
!= &init_struct_pid
)
2357 bad_fork_cleanup_thread
:
2359 bad_fork_cleanup_io
:
2362 bad_fork_cleanup_namespaces
:
2363 exit_task_namespaces(p
);
2364 bad_fork_cleanup_mm
:
2366 mm_clear_owner(p
->mm
, p
);
2369 bad_fork_cleanup_signal
:
2370 if (!(clone_flags
& CLONE_THREAD
))
2371 free_signal_struct(p
->signal
);
2372 bad_fork_cleanup_sighand
:
2373 __cleanup_sighand(p
->sighand
);
2374 bad_fork_cleanup_fs
:
2375 exit_fs(p
); /* blocking */
2376 bad_fork_cleanup_files
:
2377 exit_files(p
); /* blocking */
2378 bad_fork_cleanup_semundo
:
2380 bad_fork_cleanup_security
:
2381 security_task_free(p
);
2382 bad_fork_cleanup_audit
:
2384 bad_fork_cleanup_perf
:
2385 perf_event_free_task(p
);
2386 bad_fork_cleanup_policy
:
2387 lockdep_free_task(p
);
2389 mpol_put(p
->mempolicy
);
2390 bad_fork_cleanup_threadgroup_lock
:
2392 delayacct_tsk_free(p
);
2393 bad_fork_cleanup_count
:
2394 dec_rlimit_ucounts(task_ucounts(p
), UCOUNT_RLIMIT_NPROC
, 1);
2397 WRITE_ONCE(p
->__state
, TASK_DEAD
);
2399 delayed_free_task(p
);
2401 spin_lock_irq(¤t
->sighand
->siglock
);
2402 hlist_del_init(&delayed
.node
);
2403 spin_unlock_irq(¤t
->sighand
->siglock
);
2404 return ERR_PTR(retval
);
2407 static inline void init_idle_pids(struct task_struct
*idle
)
2411 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2412 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2413 init_task_pid(idle
, type
, &init_struct_pid
);
2417 struct task_struct
* __init
fork_idle(int cpu
)
2419 struct task_struct
*task
;
2420 struct kernel_clone_args args
= {
2424 task
= copy_process(&init_struct_pid
, 0, cpu_to_node(cpu
), &args
);
2425 if (!IS_ERR(task
)) {
2426 init_idle_pids(task
);
2427 init_idle(task
, cpu
);
2433 struct mm_struct
*copy_init_mm(void)
2435 return dup_mm(NULL
, &init_mm
);
2439 * This is like kernel_clone(), but shaved down and tailored to just
2440 * creating io_uring workers. It returns a created task, or an error pointer.
2441 * The returned task is inactive, and the caller must fire it up through
2442 * wake_up_new_task(p). All signals are blocked in the created task.
2444 struct task_struct
*create_io_thread(int (*fn
)(void *), void *arg
, int node
)
2446 unsigned long flags
= CLONE_FS
|CLONE_FILES
|CLONE_SIGHAND
|CLONE_THREAD
|
2448 struct kernel_clone_args args
= {
2449 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2450 CLONE_UNTRACED
) & ~CSIGNAL
),
2451 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2452 .stack
= (unsigned long)fn
,
2453 .stack_size
= (unsigned long)arg
,
2457 return copy_process(NULL
, 0, node
, &args
);
2461 * Ok, this is the main fork-routine.
2463 * It copies the process, and if successful kick-starts
2464 * it and waits for it to finish using the VM if required.
2466 * args->exit_signal is expected to be checked for sanity by the caller.
2468 pid_t
kernel_clone(struct kernel_clone_args
*args
)
2470 u64 clone_flags
= args
->flags
;
2471 struct completion vfork
;
2473 struct task_struct
*p
;
2478 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2479 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2480 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2481 * field in struct clone_args and it still doesn't make sense to have
2482 * them both point at the same memory location. Performing this check
2483 * here has the advantage that we don't need to have a separate helper
2484 * to check for legacy clone().
2486 if ((args
->flags
& CLONE_PIDFD
) &&
2487 (args
->flags
& CLONE_PARENT_SETTID
) &&
2488 (args
->pidfd
== args
->parent_tid
))
2492 * Determine whether and which event to report to ptracer. When
2493 * called from kernel_thread or CLONE_UNTRACED is explicitly
2494 * requested, no event is reported; otherwise, report if the event
2495 * for the type of forking is enabled.
2497 if (!(clone_flags
& CLONE_UNTRACED
)) {
2498 if (clone_flags
& CLONE_VFORK
)
2499 trace
= PTRACE_EVENT_VFORK
;
2500 else if (args
->exit_signal
!= SIGCHLD
)
2501 trace
= PTRACE_EVENT_CLONE
;
2503 trace
= PTRACE_EVENT_FORK
;
2505 if (likely(!ptrace_event_enabled(current
, trace
)))
2509 p
= copy_process(NULL
, trace
, NUMA_NO_NODE
, args
);
2510 add_latent_entropy();
2516 * Do this prior waking up the new thread - the thread pointer
2517 * might get invalid after that point, if the thread exits quickly.
2519 trace_sched_process_fork(current
, p
);
2521 pid
= get_task_pid(p
, PIDTYPE_PID
);
2524 if (clone_flags
& CLONE_PARENT_SETTID
)
2525 put_user(nr
, args
->parent_tid
);
2527 if (clone_flags
& CLONE_VFORK
) {
2528 p
->vfork_done
= &vfork
;
2529 init_completion(&vfork
);
2533 wake_up_new_task(p
);
2535 /* forking complete and child started to run, tell ptracer */
2536 if (unlikely(trace
))
2537 ptrace_event_pid(trace
, pid
);
2539 if (clone_flags
& CLONE_VFORK
) {
2540 if (!wait_for_vfork_done(p
, &vfork
))
2541 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2549 * Create a kernel thread.
2551 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2553 struct kernel_clone_args args
= {
2554 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2555 CLONE_UNTRACED
) & ~CSIGNAL
),
2556 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2557 .stack
= (unsigned long)fn
,
2558 .stack_size
= (unsigned long)arg
,
2561 return kernel_clone(&args
);
2564 #ifdef __ARCH_WANT_SYS_FORK
2565 SYSCALL_DEFINE0(fork
)
2568 struct kernel_clone_args args
= {
2569 .exit_signal
= SIGCHLD
,
2572 return kernel_clone(&args
);
2574 /* can not support in nommu mode */
2580 #ifdef __ARCH_WANT_SYS_VFORK
2581 SYSCALL_DEFINE0(vfork
)
2583 struct kernel_clone_args args
= {
2584 .flags
= CLONE_VFORK
| CLONE_VM
,
2585 .exit_signal
= SIGCHLD
,
2588 return kernel_clone(&args
);
2592 #ifdef __ARCH_WANT_SYS_CLONE
2593 #ifdef CONFIG_CLONE_BACKWARDS
2594 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2595 int __user
*, parent_tidptr
,
2597 int __user
*, child_tidptr
)
2598 #elif defined(CONFIG_CLONE_BACKWARDS2)
2599 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2600 int __user
*, parent_tidptr
,
2601 int __user
*, child_tidptr
,
2603 #elif defined(CONFIG_CLONE_BACKWARDS3)
2604 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2606 int __user
*, parent_tidptr
,
2607 int __user
*, child_tidptr
,
2610 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2611 int __user
*, parent_tidptr
,
2612 int __user
*, child_tidptr
,
2616 struct kernel_clone_args args
= {
2617 .flags
= (lower_32_bits(clone_flags
) & ~CSIGNAL
),
2618 .pidfd
= parent_tidptr
,
2619 .child_tid
= child_tidptr
,
2620 .parent_tid
= parent_tidptr
,
2621 .exit_signal
= (lower_32_bits(clone_flags
) & CSIGNAL
),
2626 return kernel_clone(&args
);
2630 #ifdef __ARCH_WANT_SYS_CLONE3
2632 noinline
static int copy_clone_args_from_user(struct kernel_clone_args
*kargs
,
2633 struct clone_args __user
*uargs
,
2637 struct clone_args args
;
2638 pid_t
*kset_tid
= kargs
->set_tid
;
2640 BUILD_BUG_ON(offsetofend(struct clone_args
, tls
) !=
2641 CLONE_ARGS_SIZE_VER0
);
2642 BUILD_BUG_ON(offsetofend(struct clone_args
, set_tid_size
) !=
2643 CLONE_ARGS_SIZE_VER1
);
2644 BUILD_BUG_ON(offsetofend(struct clone_args
, cgroup
) !=
2645 CLONE_ARGS_SIZE_VER2
);
2646 BUILD_BUG_ON(sizeof(struct clone_args
) != CLONE_ARGS_SIZE_VER2
);
2648 if (unlikely(usize
> PAGE_SIZE
))
2650 if (unlikely(usize
< CLONE_ARGS_SIZE_VER0
))
2653 err
= copy_struct_from_user(&args
, sizeof(args
), uargs
, usize
);
2657 if (unlikely(args
.set_tid_size
> MAX_PID_NS_LEVEL
))
2660 if (unlikely(!args
.set_tid
&& args
.set_tid_size
> 0))
2663 if (unlikely(args
.set_tid
&& args
.set_tid_size
== 0))
2667 * Verify that higher 32bits of exit_signal are unset and that
2668 * it is a valid signal
2670 if (unlikely((args
.exit_signal
& ~((u64
)CSIGNAL
)) ||
2671 !valid_signal(args
.exit_signal
)))
2674 if ((args
.flags
& CLONE_INTO_CGROUP
) &&
2675 (args
.cgroup
> INT_MAX
|| usize
< CLONE_ARGS_SIZE_VER2
))
2678 *kargs
= (struct kernel_clone_args
){
2679 .flags
= args
.flags
,
2680 .pidfd
= u64_to_user_ptr(args
.pidfd
),
2681 .child_tid
= u64_to_user_ptr(args
.child_tid
),
2682 .parent_tid
= u64_to_user_ptr(args
.parent_tid
),
2683 .exit_signal
= args
.exit_signal
,
2684 .stack
= args
.stack
,
2685 .stack_size
= args
.stack_size
,
2687 .set_tid_size
= args
.set_tid_size
,
2688 .cgroup
= args
.cgroup
,
2692 copy_from_user(kset_tid
, u64_to_user_ptr(args
.set_tid
),
2693 (kargs
->set_tid_size
* sizeof(pid_t
))))
2696 kargs
->set_tid
= kset_tid
;
2702 * clone3_stack_valid - check and prepare stack
2703 * @kargs: kernel clone args
2705 * Verify that the stack arguments userspace gave us are sane.
2706 * In addition, set the stack direction for userspace since it's easy for us to
2709 static inline bool clone3_stack_valid(struct kernel_clone_args
*kargs
)
2711 if (kargs
->stack
== 0) {
2712 if (kargs
->stack_size
> 0)
2715 if (kargs
->stack_size
== 0)
2718 if (!access_ok((void __user
*)kargs
->stack
, kargs
->stack_size
))
2721 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2722 kargs
->stack
+= kargs
->stack_size
;
2729 static bool clone3_args_valid(struct kernel_clone_args
*kargs
)
2731 /* Verify that no unknown flags are passed along. */
2733 ~(CLONE_LEGACY_FLAGS
| CLONE_CLEAR_SIGHAND
| CLONE_INTO_CGROUP
))
2737 * - make the CLONE_DETACHED bit reusable for clone3
2738 * - make the CSIGNAL bits reusable for clone3
2740 if (kargs
->flags
& (CLONE_DETACHED
| CSIGNAL
))
2743 if ((kargs
->flags
& (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
)) ==
2744 (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
))
2747 if ((kargs
->flags
& (CLONE_THREAD
| CLONE_PARENT
)) &&
2751 if (!clone3_stack_valid(kargs
))
2758 * clone3 - create a new process with specific properties
2759 * @uargs: argument structure
2760 * @size: size of @uargs
2762 * clone3() is the extensible successor to clone()/clone2().
2763 * It takes a struct as argument that is versioned by its size.
2765 * Return: On success, a positive PID for the child process.
2766 * On error, a negative errno number.
2768 SYSCALL_DEFINE2(clone3
, struct clone_args __user
*, uargs
, size_t, size
)
2772 struct kernel_clone_args kargs
;
2773 pid_t set_tid
[MAX_PID_NS_LEVEL
];
2775 kargs
.set_tid
= set_tid
;
2777 err
= copy_clone_args_from_user(&kargs
, uargs
, size
);
2781 if (!clone3_args_valid(&kargs
))
2784 return kernel_clone(&kargs
);
2788 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2790 struct task_struct
*leader
, *parent
, *child
;
2793 read_lock(&tasklist_lock
);
2794 leader
= top
= top
->group_leader
;
2796 for_each_thread(leader
, parent
) {
2797 list_for_each_entry(child
, &parent
->children
, sibling
) {
2798 res
= visitor(child
, data
);
2810 if (leader
!= top
) {
2812 parent
= child
->real_parent
;
2813 leader
= parent
->group_leader
;
2817 read_unlock(&tasklist_lock
);
2820 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2821 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2824 static void sighand_ctor(void *data
)
2826 struct sighand_struct
*sighand
= data
;
2828 spin_lock_init(&sighand
->siglock
);
2829 init_waitqueue_head(&sighand
->signalfd_wqh
);
2832 void __init
proc_caches_init(void)
2834 unsigned int mm_size
;
2836 sighand_cachep
= kmem_cache_create("sighand_cache",
2837 sizeof(struct sighand_struct
), 0,
2838 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
2839 SLAB_ACCOUNT
, sighand_ctor
);
2840 signal_cachep
= kmem_cache_create("signal_cache",
2841 sizeof(struct signal_struct
), 0,
2842 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2844 files_cachep
= kmem_cache_create("files_cache",
2845 sizeof(struct files_struct
), 0,
2846 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2848 fs_cachep
= kmem_cache_create("fs_cache",
2849 sizeof(struct fs_struct
), 0,
2850 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2854 * The mm_cpumask is located at the end of mm_struct, and is
2855 * dynamically sized based on the maximum CPU number this system
2856 * can have, taking hotplug into account (nr_cpu_ids).
2858 mm_size
= sizeof(struct mm_struct
) + cpumask_size();
2860 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
2861 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
2862 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2863 offsetof(struct mm_struct
, saved_auxv
),
2864 sizeof_field(struct mm_struct
, saved_auxv
),
2866 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2868 nsproxy_cache_init();
2872 * Check constraints on flags passed to the unshare system call.
2874 static int check_unshare_flags(unsigned long unshare_flags
)
2876 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2877 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2878 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2879 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
|
2883 * Not implemented, but pretend it works if there is nothing
2884 * to unshare. Note that unsharing the address space or the
2885 * signal handlers also need to unshare the signal queues (aka
2888 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2889 if (!thread_group_empty(current
))
2892 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2893 if (refcount_read(¤t
->sighand
->count
) > 1)
2896 if (unshare_flags
& CLONE_VM
) {
2897 if (!current_is_single_threaded())
2905 * Unshare the filesystem structure if it is being shared
2907 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2909 struct fs_struct
*fs
= current
->fs
;
2911 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2914 /* don't need lock here; in the worst case we'll do useless copy */
2918 *new_fsp
= copy_fs_struct(fs
);
2926 * Unshare file descriptor table if it is being shared
2928 int unshare_fd(unsigned long unshare_flags
, unsigned int max_fds
,
2929 struct files_struct
**new_fdp
)
2931 struct files_struct
*fd
= current
->files
;
2934 if ((unshare_flags
& CLONE_FILES
) &&
2935 (fd
&& atomic_read(&fd
->count
) > 1)) {
2936 *new_fdp
= dup_fd(fd
, max_fds
, &error
);
2945 * unshare allows a process to 'unshare' part of the process
2946 * context which was originally shared using clone. copy_*
2947 * functions used by kernel_clone() cannot be used here directly
2948 * because they modify an inactive task_struct that is being
2949 * constructed. Here we are modifying the current, active,
2952 int ksys_unshare(unsigned long unshare_flags
)
2954 struct fs_struct
*fs
, *new_fs
= NULL
;
2955 struct files_struct
*fd
, *new_fd
= NULL
;
2956 struct cred
*new_cred
= NULL
;
2957 struct nsproxy
*new_nsproxy
= NULL
;
2962 * If unsharing a user namespace must also unshare the thread group
2963 * and unshare the filesystem root and working directories.
2965 if (unshare_flags
& CLONE_NEWUSER
)
2966 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2968 * If unsharing vm, must also unshare signal handlers.
2970 if (unshare_flags
& CLONE_VM
)
2971 unshare_flags
|= CLONE_SIGHAND
;
2973 * If unsharing a signal handlers, must also unshare the signal queues.
2975 if (unshare_flags
& CLONE_SIGHAND
)
2976 unshare_flags
|= CLONE_THREAD
;
2978 * If unsharing namespace, must also unshare filesystem information.
2980 if (unshare_flags
& CLONE_NEWNS
)
2981 unshare_flags
|= CLONE_FS
;
2983 err
= check_unshare_flags(unshare_flags
);
2985 goto bad_unshare_out
;
2987 * CLONE_NEWIPC must also detach from the undolist: after switching
2988 * to a new ipc namespace, the semaphore arrays from the old
2989 * namespace are unreachable.
2991 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2993 err
= unshare_fs(unshare_flags
, &new_fs
);
2995 goto bad_unshare_out
;
2996 err
= unshare_fd(unshare_flags
, NR_OPEN_MAX
, &new_fd
);
2998 goto bad_unshare_cleanup_fs
;
2999 err
= unshare_userns(unshare_flags
, &new_cred
);
3001 goto bad_unshare_cleanup_fd
;
3002 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
3005 goto bad_unshare_cleanup_cred
;
3008 err
= set_cred_ucounts(new_cred
);
3010 goto bad_unshare_cleanup_cred
;
3013 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
3016 * CLONE_SYSVSEM is equivalent to sys_exit().
3020 if (unshare_flags
& CLONE_NEWIPC
) {
3021 /* Orphan segments in old ns (see sem above). */
3023 shm_init_task(current
);
3027 switch_task_namespaces(current
, new_nsproxy
);
3033 spin_lock(&fs
->lock
);
3034 current
->fs
= new_fs
;
3039 spin_unlock(&fs
->lock
);
3043 fd
= current
->files
;
3044 current
->files
= new_fd
;
3048 task_unlock(current
);
3051 /* Install the new user namespace */
3052 commit_creds(new_cred
);
3057 perf_event_namespaces(current
);
3059 bad_unshare_cleanup_cred
:
3062 bad_unshare_cleanup_fd
:
3064 put_files_struct(new_fd
);
3066 bad_unshare_cleanup_fs
:
3068 free_fs_struct(new_fs
);
3074 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
3076 return ksys_unshare(unshare_flags
);
3080 * Helper to unshare the files of the current task.
3081 * We don't want to expose copy_files internals to
3082 * the exec layer of the kernel.
3085 int unshare_files(void)
3087 struct task_struct
*task
= current
;
3088 struct files_struct
*old
, *copy
= NULL
;
3091 error
= unshare_fd(CLONE_FILES
, NR_OPEN_MAX
, ©
);
3099 put_files_struct(old
);
3103 int sysctl_max_threads(struct ctl_table
*table
, int write
,
3104 void *buffer
, size_t *lenp
, loff_t
*ppos
)
3108 int threads
= max_threads
;
3110 int max
= MAX_THREADS
;
3117 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
3121 max_threads
= threads
;