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>
99 #include <asm/pgtable.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 /* Clear the KASAN shadow of the stack. */
229 kasan_unpoison_shadow(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
= 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 mod_memcg_page_state(vm
->pages
[i
],
282 MEMCG_KERNEL_STACK_KB
,
283 -(int)(PAGE_SIZE
/ 1024));
285 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
288 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
289 if (this_cpu_cmpxchg(cached_stacks
[i
],
290 NULL
, tsk
->stack_vm_area
) != NULL
)
296 vfree_atomic(tsk
->stack
);
301 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
304 static struct kmem_cache
*thread_stack_cache
;
306 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
309 unsigned long *stack
;
310 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
315 static void free_thread_stack(struct task_struct
*tsk
)
317 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
320 void thread_stack_cache_init(void)
322 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
323 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
325 BUG_ON(thread_stack_cache
== NULL
);
330 /* SLAB cache for signal_struct structures (tsk->signal) */
331 static struct kmem_cache
*signal_cachep
;
333 /* SLAB cache for sighand_struct structures (tsk->sighand) */
334 struct kmem_cache
*sighand_cachep
;
336 /* SLAB cache for files_struct structures (tsk->files) */
337 struct kmem_cache
*files_cachep
;
339 /* SLAB cache for fs_struct structures (tsk->fs) */
340 struct kmem_cache
*fs_cachep
;
342 /* SLAB cache for vm_area_struct structures */
343 static struct kmem_cache
*vm_area_cachep
;
345 /* SLAB cache for mm_struct structures (tsk->mm) */
346 static struct kmem_cache
*mm_cachep
;
348 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
350 struct vm_area_struct
*vma
;
352 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
358 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
360 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
364 INIT_LIST_HEAD(&new->anon_vma_chain
);
365 new->vm_next
= new->vm_prev
= NULL
;
370 void vm_area_free(struct vm_area_struct
*vma
)
372 kmem_cache_free(vm_area_cachep
, vma
);
375 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
377 void *stack
= task_stack_page(tsk
);
378 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
380 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
385 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
387 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
388 mod_zone_page_state(page_zone(vm
->pages
[i
]),
390 PAGE_SIZE
/ 1024 * account
);
394 * All stack pages are in the same zone and belong to the
397 struct page
*first_page
= virt_to_page(stack
);
399 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
400 THREAD_SIZE
/ 1024 * account
);
402 mod_memcg_obj_state(stack
, MEMCG_KERNEL_STACK_KB
,
403 account
* (THREAD_SIZE
/ 1024));
407 static int memcg_charge_kernel_stack(struct task_struct
*tsk
)
409 #ifdef CONFIG_VMAP_STACK
410 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
416 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
418 * If memcg_kmem_charge_page() fails, page->mem_cgroup
419 * pointer is NULL, and both memcg_kmem_uncharge_page()
420 * and mod_memcg_page_state() in free_thread_stack()
421 * will ignore this page. So it's safe.
423 ret
= memcg_kmem_charge_page(vm
->pages
[i
], GFP_KERNEL
,
428 mod_memcg_page_state(vm
->pages
[i
],
429 MEMCG_KERNEL_STACK_KB
,
437 static void release_task_stack(struct task_struct
*tsk
)
439 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
440 return; /* Better to leak the stack than to free prematurely */
442 account_kernel_stack(tsk
, -1);
443 free_thread_stack(tsk
);
445 #ifdef CONFIG_VMAP_STACK
446 tsk
->stack_vm_area
= NULL
;
450 #ifdef CONFIG_THREAD_INFO_IN_TASK
451 void put_task_stack(struct task_struct
*tsk
)
453 if (refcount_dec_and_test(&tsk
->stack_refcount
))
454 release_task_stack(tsk
);
458 void free_task(struct task_struct
*tsk
)
462 #ifndef CONFIG_THREAD_INFO_IN_TASK
464 * The task is finally done with both the stack and thread_info,
467 release_task_stack(tsk
);
470 * If the task had a separate stack allocation, it should be gone
473 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
475 rt_mutex_debug_task_free(tsk
);
476 ftrace_graph_exit_task(tsk
);
477 put_seccomp_filter(tsk
);
478 arch_release_task_struct(tsk
);
479 if (tsk
->flags
& PF_KTHREAD
)
480 free_kthread_struct(tsk
);
481 free_task_struct(tsk
);
483 EXPORT_SYMBOL(free_task
);
486 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
487 struct mm_struct
*oldmm
)
489 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
490 struct rb_node
**rb_link
, *rb_parent
;
492 unsigned long charge
;
495 uprobe_start_dup_mmap();
496 if (down_write_killable(&oldmm
->mmap_sem
)) {
498 goto fail_uprobe_end
;
500 flush_cache_dup_mm(oldmm
);
501 uprobe_dup_mmap(oldmm
, mm
);
503 * Not linked in yet - no deadlock potential:
505 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
507 /* No ordering required: file already has been exposed. */
508 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
510 mm
->total_vm
= oldmm
->total_vm
;
511 mm
->data_vm
= oldmm
->data_vm
;
512 mm
->exec_vm
= oldmm
->exec_vm
;
513 mm
->stack_vm
= oldmm
->stack_vm
;
515 rb_link
= &mm
->mm_rb
.rb_node
;
518 retval
= ksm_fork(mm
, oldmm
);
521 retval
= khugepaged_fork(mm
, oldmm
);
526 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
529 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
530 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
535 * Don't duplicate many vmas if we've been oom-killed (for
538 if (fatal_signal_pending(current
)) {
542 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
543 unsigned long len
= vma_pages(mpnt
);
545 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
549 tmp
= vm_area_dup(mpnt
);
552 retval
= vma_dup_policy(mpnt
, tmp
);
554 goto fail_nomem_policy
;
556 retval
= dup_userfaultfd(tmp
, &uf
);
558 goto fail_nomem_anon_vma_fork
;
559 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
561 * VM_WIPEONFORK gets a clean slate in the child.
562 * Don't prepare anon_vma until fault since we don't
563 * copy page for current vma.
565 tmp
->anon_vma
= NULL
;
566 } else if (anon_vma_fork(tmp
, mpnt
))
567 goto fail_nomem_anon_vma_fork
;
568 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
571 struct inode
*inode
= file_inode(file
);
572 struct address_space
*mapping
= file
->f_mapping
;
575 if (tmp
->vm_flags
& VM_DENYWRITE
)
576 atomic_dec(&inode
->i_writecount
);
577 i_mmap_lock_write(mapping
);
578 if (tmp
->vm_flags
& VM_SHARED
)
579 atomic_inc(&mapping
->i_mmap_writable
);
580 flush_dcache_mmap_lock(mapping
);
581 /* insert tmp into the share list, just after mpnt */
582 vma_interval_tree_insert_after(tmp
, mpnt
,
584 flush_dcache_mmap_unlock(mapping
);
585 i_mmap_unlock_write(mapping
);
589 * Clear hugetlb-related page reserves for children. This only
590 * affects MAP_PRIVATE mappings. Faults generated by the child
591 * are not guaranteed to succeed, even if read-only
593 if (is_vm_hugetlb_page(tmp
))
594 reset_vma_resv_huge_pages(tmp
);
597 * Link in the new vma and copy the page table entries.
600 pprev
= &tmp
->vm_next
;
604 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
605 rb_link
= &tmp
->vm_rb
.rb_right
;
606 rb_parent
= &tmp
->vm_rb
;
609 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
610 retval
= copy_page_range(mm
, oldmm
, mpnt
);
612 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
613 tmp
->vm_ops
->open(tmp
);
618 /* a new mm has just been created */
619 retval
= arch_dup_mmap(oldmm
, mm
);
621 up_write(&mm
->mmap_sem
);
623 up_write(&oldmm
->mmap_sem
);
624 dup_userfaultfd_complete(&uf
);
626 uprobe_end_dup_mmap();
628 fail_nomem_anon_vma_fork
:
629 mpol_put(vma_policy(tmp
));
634 vm_unacct_memory(charge
);
638 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
640 mm
->pgd
= pgd_alloc(mm
);
641 if (unlikely(!mm
->pgd
))
646 static inline void mm_free_pgd(struct mm_struct
*mm
)
648 pgd_free(mm
, mm
->pgd
);
651 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
653 down_write(&oldmm
->mmap_sem
);
654 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
655 up_write(&oldmm
->mmap_sem
);
658 #define mm_alloc_pgd(mm) (0)
659 #define mm_free_pgd(mm)
660 #endif /* CONFIG_MMU */
662 static void check_mm(struct mm_struct
*mm
)
666 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types
) != NR_MM_COUNTERS
,
667 "Please make sure 'struct resident_page_types[]' is updated as well");
669 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
670 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
673 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
674 mm
, resident_page_types
[i
], x
);
677 if (mm_pgtables_bytes(mm
))
678 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
679 mm_pgtables_bytes(mm
));
681 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
682 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
686 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
687 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
690 * Called when the last reference to the mm
691 * is dropped: either by a lazy thread or by
692 * mmput. Free the page directory and the mm.
694 void __mmdrop(struct mm_struct
*mm
)
696 BUG_ON(mm
== &init_mm
);
697 WARN_ON_ONCE(mm
== current
->mm
);
698 WARN_ON_ONCE(mm
== current
->active_mm
);
701 mmu_notifier_subscriptions_destroy(mm
);
703 put_user_ns(mm
->user_ns
);
706 EXPORT_SYMBOL_GPL(__mmdrop
);
708 static void mmdrop_async_fn(struct work_struct
*work
)
710 struct mm_struct
*mm
;
712 mm
= container_of(work
, struct mm_struct
, async_put_work
);
716 static void mmdrop_async(struct mm_struct
*mm
)
718 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
719 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
720 schedule_work(&mm
->async_put_work
);
724 static inline void free_signal_struct(struct signal_struct
*sig
)
726 taskstats_tgid_free(sig
);
727 sched_autogroup_exit(sig
);
729 * __mmdrop is not safe to call from softirq context on x86 due to
730 * pgd_dtor so postpone it to the async context
733 mmdrop_async(sig
->oom_mm
);
734 kmem_cache_free(signal_cachep
, sig
);
737 static inline void put_signal_struct(struct signal_struct
*sig
)
739 if (refcount_dec_and_test(&sig
->sigcnt
))
740 free_signal_struct(sig
);
743 void __put_task_struct(struct task_struct
*tsk
)
745 WARN_ON(!tsk
->exit_state
);
746 WARN_ON(refcount_read(&tsk
->usage
));
747 WARN_ON(tsk
== current
);
750 task_numa_free(tsk
, true);
751 security_task_free(tsk
);
753 delayacct_tsk_free(tsk
);
754 put_signal_struct(tsk
->signal
);
756 if (!profile_handoff_task(tsk
))
759 EXPORT_SYMBOL_GPL(__put_task_struct
);
761 void __init __weak
arch_task_cache_init(void) { }
766 static void set_max_threads(unsigned int max_threads_suggested
)
769 unsigned long nr_pages
= totalram_pages();
772 * The number of threads shall be limited such that the thread
773 * structures may only consume a small part of the available memory.
775 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
776 threads
= MAX_THREADS
;
778 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
779 (u64
) THREAD_SIZE
* 8UL);
781 if (threads
> max_threads_suggested
)
782 threads
= max_threads_suggested
;
784 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
787 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
788 /* Initialized by the architecture: */
789 int arch_task_struct_size __read_mostly
;
792 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
793 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
795 /* Fetch thread_struct whitelist for the architecture. */
796 arch_thread_struct_whitelist(offset
, size
);
799 * Handle zero-sized whitelist or empty thread_struct, otherwise
800 * adjust offset to position of thread_struct in task_struct.
802 if (unlikely(*size
== 0))
805 *offset
+= offsetof(struct task_struct
, thread
);
807 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
809 void __init
fork_init(void)
812 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
813 #ifndef ARCH_MIN_TASKALIGN
814 #define ARCH_MIN_TASKALIGN 0
816 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
817 unsigned long useroffset
, usersize
;
819 /* create a slab on which task_structs can be allocated */
820 task_struct_whitelist(&useroffset
, &usersize
);
821 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
822 arch_task_struct_size
, align
,
823 SLAB_PANIC
|SLAB_ACCOUNT
,
824 useroffset
, usersize
, NULL
);
827 /* do the arch specific task caches init */
828 arch_task_cache_init();
830 set_max_threads(MAX_THREADS
);
832 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
833 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
834 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
835 init_task
.signal
->rlim
[RLIMIT_NPROC
];
837 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
838 init_user_ns
.ucount_max
[i
] = max_threads
/2;
841 #ifdef CONFIG_VMAP_STACK
842 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
843 NULL
, free_vm_stack_cache
);
848 lockdep_init_task(&init_task
);
852 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
853 struct task_struct
*src
)
859 void set_task_stack_end_magic(struct task_struct
*tsk
)
861 unsigned long *stackend
;
863 stackend
= end_of_stack(tsk
);
864 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
867 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
869 struct task_struct
*tsk
;
870 unsigned long *stack
;
871 struct vm_struct
*stack_vm_area __maybe_unused
;
874 if (node
== NUMA_NO_NODE
)
875 node
= tsk_fork_get_node(orig
);
876 tsk
= alloc_task_struct_node(node
);
880 stack
= alloc_thread_stack_node(tsk
, node
);
884 if (memcg_charge_kernel_stack(tsk
))
887 stack_vm_area
= task_stack_vm_area(tsk
);
889 err
= arch_dup_task_struct(tsk
, orig
);
892 * arch_dup_task_struct() clobbers the stack-related fields. Make
893 * sure they're properly initialized before using any stack-related
897 #ifdef CONFIG_VMAP_STACK
898 tsk
->stack_vm_area
= stack_vm_area
;
900 #ifdef CONFIG_THREAD_INFO_IN_TASK
901 refcount_set(&tsk
->stack_refcount
, 1);
907 err
= scs_prepare(tsk
, node
);
911 #ifdef CONFIG_SECCOMP
913 * We must handle setting up seccomp filters once we're under
914 * the sighand lock in case orig has changed between now and
915 * then. Until then, filter must be NULL to avoid messing up
916 * the usage counts on the error path calling free_task.
918 tsk
->seccomp
.filter
= NULL
;
921 setup_thread_stack(tsk
, orig
);
922 clear_user_return_notifier(tsk
);
923 clear_tsk_need_resched(tsk
);
924 set_task_stack_end_magic(tsk
);
926 #ifdef CONFIG_STACKPROTECTOR
927 tsk
->stack_canary
= get_random_canary();
929 if (orig
->cpus_ptr
== &orig
->cpus_mask
)
930 tsk
->cpus_ptr
= &tsk
->cpus_mask
;
933 * One for the user space visible state that goes away when reaped.
934 * One for the scheduler.
936 refcount_set(&tsk
->rcu_users
, 2);
937 /* One for the rcu users */
938 refcount_set(&tsk
->usage
, 1);
939 #ifdef CONFIG_BLK_DEV_IO_TRACE
942 tsk
->splice_pipe
= NULL
;
943 tsk
->task_frag
.page
= NULL
;
944 tsk
->wake_q
.next
= NULL
;
946 account_kernel_stack(tsk
, 1);
950 #ifdef CONFIG_FAULT_INJECTION
954 #ifdef CONFIG_BLK_CGROUP
955 tsk
->throttle_queue
= NULL
;
956 tsk
->use_memdelay
= 0;
960 tsk
->active_memcg
= NULL
;
965 free_thread_stack(tsk
);
967 free_task_struct(tsk
);
971 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
973 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
975 static int __init
coredump_filter_setup(char *s
)
977 default_dump_filter
=
978 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
979 MMF_DUMP_FILTER_MASK
;
983 __setup("coredump_filter=", coredump_filter_setup
);
985 #include <linux/init_task.h>
987 static void mm_init_aio(struct mm_struct
*mm
)
990 spin_lock_init(&mm
->ioctx_lock
);
991 mm
->ioctx_table
= NULL
;
995 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
996 struct task_struct
*p
)
1000 WRITE_ONCE(mm
->owner
, NULL
);
1004 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1011 static void mm_init_uprobes_state(struct mm_struct
*mm
)
1013 #ifdef CONFIG_UPROBES
1014 mm
->uprobes_state
.xol_area
= NULL
;
1018 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
1019 struct user_namespace
*user_ns
)
1022 mm
->mm_rb
= RB_ROOT
;
1023 mm
->vmacache_seqnum
= 0;
1024 atomic_set(&mm
->mm_users
, 1);
1025 atomic_set(&mm
->mm_count
, 1);
1026 init_rwsem(&mm
->mmap_sem
);
1027 INIT_LIST_HEAD(&mm
->mmlist
);
1028 mm
->core_state
= NULL
;
1029 mm_pgtables_bytes_init(mm
);
1032 atomic64_set(&mm
->pinned_vm
, 0);
1033 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
1034 spin_lock_init(&mm
->page_table_lock
);
1035 spin_lock_init(&mm
->arg_lock
);
1036 mm_init_cpumask(mm
);
1038 mm_init_owner(mm
, p
);
1039 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1040 mmu_notifier_subscriptions_init(mm
);
1041 init_tlb_flush_pending(mm
);
1042 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1043 mm
->pmd_huge_pte
= NULL
;
1045 mm_init_uprobes_state(mm
);
1048 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1049 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1051 mm
->flags
= default_dump_filter
;
1055 if (mm_alloc_pgd(mm
))
1058 if (init_new_context(p
, mm
))
1059 goto fail_nocontext
;
1061 mm
->user_ns
= get_user_ns(user_ns
);
1072 * Allocate and initialize an mm_struct.
1074 struct mm_struct
*mm_alloc(void)
1076 struct mm_struct
*mm
;
1082 memset(mm
, 0, sizeof(*mm
));
1083 return mm_init(mm
, current
, current_user_ns());
1086 static inline void __mmput(struct mm_struct
*mm
)
1088 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1090 uprobe_clear_state(mm
);
1093 khugepaged_exit(mm
); /* must run before exit_mmap */
1095 mm_put_huge_zero_page(mm
);
1096 set_mm_exe_file(mm
, NULL
);
1097 if (!list_empty(&mm
->mmlist
)) {
1098 spin_lock(&mmlist_lock
);
1099 list_del(&mm
->mmlist
);
1100 spin_unlock(&mmlist_lock
);
1103 module_put(mm
->binfmt
->module
);
1108 * Decrement the use count and release all resources for an mm.
1110 void mmput(struct mm_struct
*mm
)
1114 if (atomic_dec_and_test(&mm
->mm_users
))
1117 EXPORT_SYMBOL_GPL(mmput
);
1120 static void mmput_async_fn(struct work_struct
*work
)
1122 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1128 void mmput_async(struct mm_struct
*mm
)
1130 if (atomic_dec_and_test(&mm
->mm_users
)) {
1131 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1132 schedule_work(&mm
->async_put_work
);
1138 * set_mm_exe_file - change a reference to the mm's executable file
1140 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1142 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1143 * invocations: in mmput() nobody alive left, in execve task is single
1144 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1145 * mm->exe_file, but does so without using set_mm_exe_file() in order
1146 * to do avoid the need for any locks.
1148 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1150 struct file
*old_exe_file
;
1153 * It is safe to dereference the exe_file without RCU as
1154 * this function is only called if nobody else can access
1155 * this mm -- see comment above for justification.
1157 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1160 get_file(new_exe_file
);
1161 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1167 * get_mm_exe_file - acquire a reference to the mm's executable file
1169 * Returns %NULL if mm has no associated executable file.
1170 * User must release file via fput().
1172 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1174 struct file
*exe_file
;
1177 exe_file
= rcu_dereference(mm
->exe_file
);
1178 if (exe_file
&& !get_file_rcu(exe_file
))
1183 EXPORT_SYMBOL(get_mm_exe_file
);
1186 * get_task_exe_file - acquire a reference to the task's executable file
1188 * Returns %NULL if task's mm (if any) has no associated executable file or
1189 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1190 * User must release file via fput().
1192 struct file
*get_task_exe_file(struct task_struct
*task
)
1194 struct file
*exe_file
= NULL
;
1195 struct mm_struct
*mm
;
1200 if (!(task
->flags
& PF_KTHREAD
))
1201 exe_file
= get_mm_exe_file(mm
);
1206 EXPORT_SYMBOL(get_task_exe_file
);
1209 * get_task_mm - acquire a reference to the task's mm
1211 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1212 * this kernel workthread has transiently adopted a user mm with use_mm,
1213 * to do its AIO) is not set and if so returns a reference to it, after
1214 * bumping up the use count. User must release the mm via mmput()
1215 * after use. Typically used by /proc and ptrace.
1217 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1219 struct mm_struct
*mm
;
1224 if (task
->flags
& PF_KTHREAD
)
1232 EXPORT_SYMBOL_GPL(get_task_mm
);
1234 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1236 struct mm_struct
*mm
;
1239 err
= mutex_lock_killable(&task
->signal
->exec_update_mutex
);
1241 return ERR_PTR(err
);
1243 mm
= get_task_mm(task
);
1244 if (mm
&& mm
!= current
->mm
&&
1245 !ptrace_may_access(task
, mode
)) {
1247 mm
= ERR_PTR(-EACCES
);
1249 mutex_unlock(&task
->signal
->exec_update_mutex
);
1254 static void complete_vfork_done(struct task_struct
*tsk
)
1256 struct completion
*vfork
;
1259 vfork
= tsk
->vfork_done
;
1260 if (likely(vfork
)) {
1261 tsk
->vfork_done
= NULL
;
1267 static int wait_for_vfork_done(struct task_struct
*child
,
1268 struct completion
*vfork
)
1272 freezer_do_not_count();
1273 cgroup_enter_frozen();
1274 killed
= wait_for_completion_killable(vfork
);
1275 cgroup_leave_frozen(false);
1280 child
->vfork_done
= NULL
;
1284 put_task_struct(child
);
1288 /* Please note the differences between mmput and mm_release.
1289 * mmput is called whenever we stop holding onto a mm_struct,
1290 * error success whatever.
1292 * mm_release is called after a mm_struct has been removed
1293 * from the current process.
1295 * This difference is important for error handling, when we
1296 * only half set up a mm_struct for a new process and need to restore
1297 * the old one. Because we mmput the new mm_struct before
1298 * restoring the old one. . .
1299 * Eric Biederman 10 January 1998
1301 static void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1303 uprobe_free_utask(tsk
);
1305 /* Get rid of any cached register state */
1306 deactivate_mm(tsk
, mm
);
1309 * Signal userspace if we're not exiting with a core dump
1310 * because we want to leave the value intact for debugging
1313 if (tsk
->clear_child_tid
) {
1314 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1315 atomic_read(&mm
->mm_users
) > 1) {
1317 * We don't check the error code - if userspace has
1318 * not set up a proper pointer then tough luck.
1320 put_user(0, tsk
->clear_child_tid
);
1321 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1322 1, NULL
, NULL
, 0, 0);
1324 tsk
->clear_child_tid
= NULL
;
1328 * All done, finally we can wake up parent and return this mm to him.
1329 * Also kthread_stop() uses this completion for synchronization.
1331 if (tsk
->vfork_done
)
1332 complete_vfork_done(tsk
);
1335 void exit_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1337 futex_exit_release(tsk
);
1338 mm_release(tsk
, mm
);
1341 void exec_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1343 futex_exec_release(tsk
);
1344 mm_release(tsk
, mm
);
1348 * dup_mm() - duplicates an existing mm structure
1349 * @tsk: the task_struct with which the new mm will be associated.
1350 * @oldmm: the mm to duplicate.
1352 * Allocates a new mm structure and duplicates the provided @oldmm structure
1355 * Return: the duplicated mm or NULL on failure.
1357 static struct mm_struct
*dup_mm(struct task_struct
*tsk
,
1358 struct mm_struct
*oldmm
)
1360 struct mm_struct
*mm
;
1367 memcpy(mm
, oldmm
, sizeof(*mm
));
1369 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1372 err
= dup_mmap(mm
, oldmm
);
1376 mm
->hiwater_rss
= get_mm_rss(mm
);
1377 mm
->hiwater_vm
= mm
->total_vm
;
1379 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1385 /* don't put binfmt in mmput, we haven't got module yet */
1387 mm_init_owner(mm
, NULL
);
1394 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1396 struct mm_struct
*mm
, *oldmm
;
1399 tsk
->min_flt
= tsk
->maj_flt
= 0;
1400 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1401 #ifdef CONFIG_DETECT_HUNG_TASK
1402 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1403 tsk
->last_switch_time
= 0;
1407 tsk
->active_mm
= NULL
;
1410 * Are we cloning a kernel thread?
1412 * We need to steal a active VM for that..
1414 oldmm
= current
->mm
;
1418 /* initialize the new vmacache entries */
1419 vmacache_flush(tsk
);
1421 if (clone_flags
& CLONE_VM
) {
1428 mm
= dup_mm(tsk
, current
->mm
);
1434 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
, &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 mutex_init(&sig
->exec_update_mutex
);
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_tsk_thread_flag(p
, TIF_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
]);
1674 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1676 if (type
== PIDTYPE_PID
)
1677 task
->thread_pid
= pid
;
1679 task
->signal
->pids
[type
] = pid
;
1682 static inline void rcu_copy_process(struct task_struct
*p
)
1684 #ifdef CONFIG_PREEMPT_RCU
1685 p
->rcu_read_lock_nesting
= 0;
1686 p
->rcu_read_unlock_special
.s
= 0;
1687 p
->rcu_blocked_node
= NULL
;
1688 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1689 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1690 #ifdef CONFIG_TASKS_RCU
1691 p
->rcu_tasks_holdout
= false;
1692 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1693 p
->rcu_tasks_idle_cpu
= -1;
1694 #endif /* #ifdef CONFIG_TASKS_RCU */
1695 #ifdef CONFIG_TASKS_TRACE_RCU
1696 p
->trc_reader_nesting
= 0;
1697 p
->trc_reader_special
.s
= 0;
1698 INIT_LIST_HEAD(&p
->trc_holdout_list
);
1699 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1702 struct pid
*pidfd_pid(const struct file
*file
)
1704 if (file
->f_op
== &pidfd_fops
)
1705 return file
->private_data
;
1707 return ERR_PTR(-EBADF
);
1710 static int pidfd_release(struct inode
*inode
, struct file
*file
)
1712 struct pid
*pid
= file
->private_data
;
1714 file
->private_data
= NULL
;
1719 #ifdef CONFIG_PROC_FS
1721 * pidfd_show_fdinfo - print information about a pidfd
1722 * @m: proc fdinfo file
1723 * @f: file referencing a pidfd
1726 * This function will print the pid that a given pidfd refers to in the
1727 * pid namespace of the procfs instance.
1728 * If the pid namespace of the process is not a descendant of the pid
1729 * namespace of the procfs instance 0 will be shown as its pid. This is
1730 * similar to calling getppid() on a process whose parent is outside of
1731 * its pid namespace.
1734 * If pid namespaces are supported then this function will also print
1735 * the pid of a given pidfd refers to for all descendant pid namespaces
1736 * starting from the current pid namespace of the instance, i.e. the
1737 * Pid field and the first entry in the NSpid field will be identical.
1738 * If the pid namespace of the process is not a descendant of the pid
1739 * namespace of the procfs instance 0 will be shown as its first NSpid
1740 * entry and no others will be shown.
1741 * Note that this differs from the Pid and NSpid fields in
1742 * /proc/<pid>/status where Pid and NSpid are always shown relative to
1743 * the pid namespace of the procfs instance. The difference becomes
1744 * obvious when sending around a pidfd between pid namespaces from a
1745 * different branch of the tree, i.e. where no ancestoral relation is
1746 * present between the pid namespaces:
1747 * - create two new pid namespaces ns1 and ns2 in the initial pid
1748 * namespace (also take care to create new mount namespaces in the
1749 * new pid namespace and mount procfs)
1750 * - create a process with a pidfd in ns1
1751 * - send pidfd from ns1 to ns2
1752 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
1753 * have exactly one entry, which is 0
1755 static void pidfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
1757 struct pid
*pid
= f
->private_data
;
1758 struct pid_namespace
*ns
;
1761 if (likely(pid_has_task(pid
, PIDTYPE_PID
))) {
1762 ns
= proc_pid_ns(file_inode(m
->file
));
1763 nr
= pid_nr_ns(pid
, ns
);
1766 seq_put_decimal_ll(m
, "Pid:\t", nr
);
1768 #ifdef CONFIG_PID_NS
1769 seq_put_decimal_ll(m
, "\nNSpid:\t", nr
);
1773 /* If nr is non-zero it means that 'pid' is valid and that
1774 * ns, i.e. the pid namespace associated with the procfs
1775 * instance, is in the pid namespace hierarchy of pid.
1776 * Start at one below the already printed level.
1778 for (i
= ns
->level
+ 1; i
<= pid
->level
; i
++)
1779 seq_put_decimal_ll(m
, "\t", pid
->numbers
[i
].nr
);
1787 * Poll support for process exit notification.
1789 static __poll_t
pidfd_poll(struct file
*file
, struct poll_table_struct
*pts
)
1791 struct task_struct
*task
;
1792 struct pid
*pid
= file
->private_data
;
1793 __poll_t poll_flags
= 0;
1795 poll_wait(file
, &pid
->wait_pidfd
, pts
);
1798 task
= pid_task(pid
, PIDTYPE_PID
);
1800 * Inform pollers only when the whole thread group exits.
1801 * If the thread group leader exits before all other threads in the
1802 * group, then poll(2) should block, similar to the wait(2) family.
1804 if (!task
|| (task
->exit_state
&& thread_group_empty(task
)))
1805 poll_flags
= EPOLLIN
| EPOLLRDNORM
;
1811 const struct file_operations pidfd_fops
= {
1812 .release
= pidfd_release
,
1814 #ifdef CONFIG_PROC_FS
1815 .show_fdinfo
= pidfd_show_fdinfo
,
1819 static void __delayed_free_task(struct rcu_head
*rhp
)
1821 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
1826 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
1828 if (IS_ENABLED(CONFIG_MEMCG
))
1829 call_rcu(&tsk
->rcu
, __delayed_free_task
);
1835 * This creates a new process as a copy of the old one,
1836 * but does not actually start it yet.
1838 * It copies the registers, and all the appropriate
1839 * parts of the process environment (as per the clone
1840 * flags). The actual kick-off is left to the caller.
1842 static __latent_entropy
struct task_struct
*copy_process(
1846 struct kernel_clone_args
*args
)
1848 int pidfd
= -1, retval
;
1849 struct task_struct
*p
;
1850 struct multiprocess_signals delayed
;
1851 struct file
*pidfile
= NULL
;
1852 u64 clone_flags
= args
->flags
;
1853 struct nsproxy
*nsp
= current
->nsproxy
;
1856 * Don't allow sharing the root directory with processes in a different
1859 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1860 return ERR_PTR(-EINVAL
);
1862 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1863 return ERR_PTR(-EINVAL
);
1866 * Thread groups must share signals as well, and detached threads
1867 * can only be started up within the thread group.
1869 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1870 return ERR_PTR(-EINVAL
);
1873 * Shared signal handlers imply shared VM. By way of the above,
1874 * thread groups also imply shared VM. Blocking this case allows
1875 * for various simplifications in other code.
1877 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1878 return ERR_PTR(-EINVAL
);
1881 * Siblings of global init remain as zombies on exit since they are
1882 * not reaped by their parent (swapper). To solve this and to avoid
1883 * multi-rooted process trees, prevent global and container-inits
1884 * from creating siblings.
1886 if ((clone_flags
& CLONE_PARENT
) &&
1887 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1888 return ERR_PTR(-EINVAL
);
1891 * If the new process will be in a different pid or user namespace
1892 * do not allow it to share a thread group with the forking task.
1894 if (clone_flags
& CLONE_THREAD
) {
1895 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1896 (task_active_pid_ns(current
) != nsp
->pid_ns_for_children
))
1897 return ERR_PTR(-EINVAL
);
1901 * If the new process will be in a different time namespace
1902 * do not allow it to share VM or a thread group with the forking task.
1904 if (clone_flags
& (CLONE_THREAD
| CLONE_VM
)) {
1905 if (nsp
->time_ns
!= nsp
->time_ns_for_children
)
1906 return ERR_PTR(-EINVAL
);
1909 if (clone_flags
& CLONE_PIDFD
) {
1911 * - CLONE_DETACHED is blocked so that we can potentially
1912 * reuse it later for CLONE_PIDFD.
1913 * - CLONE_THREAD is blocked until someone really needs it.
1915 if (clone_flags
& (CLONE_DETACHED
| CLONE_THREAD
))
1916 return ERR_PTR(-EINVAL
);
1920 * Force any signals received before this point to be delivered
1921 * before the fork happens. Collect up signals sent to multiple
1922 * processes that happen during the fork and delay them so that
1923 * they appear to happen after the fork.
1925 sigemptyset(&delayed
.signal
);
1926 INIT_HLIST_NODE(&delayed
.node
);
1928 spin_lock_irq(¤t
->sighand
->siglock
);
1929 if (!(clone_flags
& CLONE_THREAD
))
1930 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
1931 recalc_sigpending();
1932 spin_unlock_irq(¤t
->sighand
->siglock
);
1933 retval
= -ERESTARTNOINTR
;
1934 if (signal_pending(current
))
1938 p
= dup_task_struct(current
, node
);
1943 * This _must_ happen before we call free_task(), i.e. before we jump
1944 * to any of the bad_fork_* labels. This is to avoid freeing
1945 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1946 * kernel threads (PF_KTHREAD).
1948 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? args
->child_tid
: NULL
;
1950 * Clear TID on mm_release()?
1952 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? args
->child_tid
: NULL
;
1954 ftrace_graph_init_task(p
);
1956 rt_mutex_init_task(p
);
1958 #ifdef CONFIG_PROVE_LOCKING
1959 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1960 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1963 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1964 task_rlimit(p
, RLIMIT_NPROC
)) {
1965 if (p
->real_cred
->user
!= INIT_USER
&&
1966 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1969 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1971 retval
= copy_creds(p
, clone_flags
);
1976 * If multiple threads are within copy_process(), then this check
1977 * triggers too late. This doesn't hurt, the check is only there
1978 * to stop root fork bombs.
1981 if (nr_threads
>= max_threads
)
1982 goto bad_fork_cleanup_count
;
1984 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1985 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1986 p
->flags
|= PF_FORKNOEXEC
;
1987 INIT_LIST_HEAD(&p
->children
);
1988 INIT_LIST_HEAD(&p
->sibling
);
1989 rcu_copy_process(p
);
1990 p
->vfork_done
= NULL
;
1991 spin_lock_init(&p
->alloc_lock
);
1993 init_sigpending(&p
->pending
);
1995 p
->utime
= p
->stime
= p
->gtime
= 0;
1996 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1997 p
->utimescaled
= p
->stimescaled
= 0;
1999 prev_cputime_init(&p
->prev_cputime
);
2001 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2002 seqcount_init(&p
->vtime
.seqcount
);
2003 p
->vtime
.starttime
= 0;
2004 p
->vtime
.state
= VTIME_INACTIVE
;
2007 #if defined(SPLIT_RSS_COUNTING)
2008 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
2011 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
2017 task_io_accounting_init(&p
->ioac
);
2018 acct_clear_integrals(p
);
2020 posix_cputimers_init(&p
->posix_cputimers
);
2022 p
->io_context
= NULL
;
2023 audit_set_context(p
, NULL
);
2026 p
->mempolicy
= mpol_dup(p
->mempolicy
);
2027 if (IS_ERR(p
->mempolicy
)) {
2028 retval
= PTR_ERR(p
->mempolicy
);
2029 p
->mempolicy
= NULL
;
2030 goto bad_fork_cleanup_threadgroup_lock
;
2033 #ifdef CONFIG_CPUSETS
2034 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
2035 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
2036 seqcount_init(&p
->mems_allowed_seq
);
2038 #ifdef CONFIG_TRACE_IRQFLAGS
2040 p
->hardirqs_enabled
= 0;
2041 p
->hardirq_enable_ip
= 0;
2042 p
->hardirq_enable_event
= 0;
2043 p
->hardirq_disable_ip
= _THIS_IP_
;
2044 p
->hardirq_disable_event
= 0;
2045 p
->softirqs_enabled
= 1;
2046 p
->softirq_enable_ip
= _THIS_IP_
;
2047 p
->softirq_enable_event
= 0;
2048 p
->softirq_disable_ip
= 0;
2049 p
->softirq_disable_event
= 0;
2050 p
->hardirq_context
= 0;
2051 p
->softirq_context
= 0;
2054 p
->pagefault_disabled
= 0;
2056 #ifdef CONFIG_LOCKDEP
2057 lockdep_init_task(p
);
2060 #ifdef CONFIG_DEBUG_MUTEXES
2061 p
->blocked_on
= NULL
; /* not blocked yet */
2063 #ifdef CONFIG_BCACHE
2064 p
->sequential_io
= 0;
2065 p
->sequential_io_avg
= 0;
2068 /* Perform scheduler related setup. Assign this task to a CPU. */
2069 retval
= sched_fork(clone_flags
, p
);
2071 goto bad_fork_cleanup_policy
;
2073 retval
= perf_event_init_task(p
);
2075 goto bad_fork_cleanup_policy
;
2076 retval
= audit_alloc(p
);
2078 goto bad_fork_cleanup_perf
;
2079 /* copy all the process information */
2081 retval
= security_task_alloc(p
, clone_flags
);
2083 goto bad_fork_cleanup_audit
;
2084 retval
= copy_semundo(clone_flags
, p
);
2086 goto bad_fork_cleanup_security
;
2087 retval
= copy_files(clone_flags
, p
);
2089 goto bad_fork_cleanup_semundo
;
2090 retval
= copy_fs(clone_flags
, p
);
2092 goto bad_fork_cleanup_files
;
2093 retval
= copy_sighand(clone_flags
, p
);
2095 goto bad_fork_cleanup_fs
;
2096 retval
= copy_signal(clone_flags
, p
);
2098 goto bad_fork_cleanup_sighand
;
2099 retval
= copy_mm(clone_flags
, p
);
2101 goto bad_fork_cleanup_signal
;
2102 retval
= copy_namespaces(clone_flags
, p
);
2104 goto bad_fork_cleanup_mm
;
2105 retval
= copy_io(clone_flags
, p
);
2107 goto bad_fork_cleanup_namespaces
;
2108 retval
= copy_thread_tls(clone_flags
, args
->stack
, args
->stack_size
, p
,
2111 goto bad_fork_cleanup_io
;
2113 stackleak_task_init(p
);
2115 if (pid
!= &init_struct_pid
) {
2116 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
, args
->set_tid
,
2117 args
->set_tid_size
);
2119 retval
= PTR_ERR(pid
);
2120 goto bad_fork_cleanup_thread
;
2125 * This has to happen after we've potentially unshared the file
2126 * descriptor table (so that the pidfd doesn't leak into the child
2127 * if the fd table isn't shared).
2129 if (clone_flags
& CLONE_PIDFD
) {
2130 retval
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2132 goto bad_fork_free_pid
;
2136 pidfile
= anon_inode_getfile("[pidfd]", &pidfd_fops
, pid
,
2137 O_RDWR
| O_CLOEXEC
);
2138 if (IS_ERR(pidfile
)) {
2139 put_unused_fd(pidfd
);
2140 retval
= PTR_ERR(pidfile
);
2141 goto bad_fork_free_pid
;
2143 get_pid(pid
); /* held by pidfile now */
2145 retval
= put_user(pidfd
, args
->pidfd
);
2147 goto bad_fork_put_pidfd
;
2156 * sigaltstack should be cleared when sharing the same VM
2158 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
2162 * Syscall tracing and stepping should be turned off in the
2163 * child regardless of CLONE_PTRACE.
2165 user_disable_single_step(p
);
2166 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
2167 #ifdef TIF_SYSCALL_EMU
2168 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
2170 clear_tsk_latency_tracing(p
);
2172 /* ok, now we should be set up.. */
2173 p
->pid
= pid_nr(pid
);
2174 if (clone_flags
& CLONE_THREAD
) {
2175 p
->exit_signal
= -1;
2176 p
->group_leader
= current
->group_leader
;
2177 p
->tgid
= current
->tgid
;
2179 if (clone_flags
& CLONE_PARENT
)
2180 p
->exit_signal
= current
->group_leader
->exit_signal
;
2182 p
->exit_signal
= args
->exit_signal
;
2183 p
->group_leader
= p
;
2188 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2189 p
->dirty_paused_when
= 0;
2191 p
->pdeath_signal
= 0;
2192 INIT_LIST_HEAD(&p
->thread_group
);
2193 p
->task_works
= NULL
;
2196 * Ensure that the cgroup subsystem policies allow the new process to be
2197 * forked. It should be noted the the new process's css_set can be changed
2198 * between here and cgroup_post_fork() if an organisation operation is in
2201 retval
= cgroup_can_fork(p
, args
);
2203 goto bad_fork_put_pidfd
;
2206 * From this point on we must avoid any synchronous user-space
2207 * communication until we take the tasklist-lock. In particular, we do
2208 * not want user-space to be able to predict the process start-time by
2209 * stalling fork(2) after we recorded the start_time but before it is
2210 * visible to the system.
2213 p
->start_time
= ktime_get_ns();
2214 p
->start_boottime
= ktime_get_boottime_ns();
2217 * Make it visible to the rest of the system, but dont wake it up yet.
2218 * Need tasklist lock for parent etc handling!
2220 write_lock_irq(&tasklist_lock
);
2222 /* CLONE_PARENT re-uses the old parent */
2223 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2224 p
->real_parent
= current
->real_parent
;
2225 p
->parent_exec_id
= current
->parent_exec_id
;
2227 p
->real_parent
= current
;
2228 p
->parent_exec_id
= current
->self_exec_id
;
2231 klp_copy_process(p
);
2233 spin_lock(¤t
->sighand
->siglock
);
2236 * Copy seccomp details explicitly here, in case they were changed
2237 * before holding sighand lock.
2241 rseq_fork(p
, clone_flags
);
2243 /* Don't start children in a dying pid namespace */
2244 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2246 goto bad_fork_cancel_cgroup
;
2249 /* Let kill terminate clone/fork in the middle */
2250 if (fatal_signal_pending(current
)) {
2252 goto bad_fork_cancel_cgroup
;
2255 /* past the last point of failure */
2257 fd_install(pidfd
, pidfile
);
2259 init_task_pid_links(p
);
2260 if (likely(p
->pid
)) {
2261 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2263 init_task_pid(p
, PIDTYPE_PID
, pid
);
2264 if (thread_group_leader(p
)) {
2265 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2266 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2267 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2269 if (is_child_reaper(pid
)) {
2270 ns_of_pid(pid
)->child_reaper
= p
;
2271 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2273 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2274 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2276 * Inherit has_child_subreaper flag under the same
2277 * tasklist_lock with adding child to the process tree
2278 * for propagate_has_child_subreaper optimization.
2280 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2281 p
->real_parent
->signal
->is_child_subreaper
;
2282 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2283 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2284 attach_pid(p
, PIDTYPE_TGID
);
2285 attach_pid(p
, PIDTYPE_PGID
);
2286 attach_pid(p
, PIDTYPE_SID
);
2287 __this_cpu_inc(process_counts
);
2289 current
->signal
->nr_threads
++;
2290 atomic_inc(¤t
->signal
->live
);
2291 refcount_inc(¤t
->signal
->sigcnt
);
2292 task_join_group_stop(p
);
2293 list_add_tail_rcu(&p
->thread_group
,
2294 &p
->group_leader
->thread_group
);
2295 list_add_tail_rcu(&p
->thread_node
,
2296 &p
->signal
->thread_head
);
2298 attach_pid(p
, PIDTYPE_PID
);
2302 hlist_del_init(&delayed
.node
);
2303 spin_unlock(¤t
->sighand
->siglock
);
2304 syscall_tracepoint_update(p
);
2305 write_unlock_irq(&tasklist_lock
);
2307 proc_fork_connector(p
);
2308 cgroup_post_fork(p
, args
);
2311 trace_task_newtask(p
, clone_flags
);
2312 uprobe_copy_process(p
, clone_flags
);
2316 bad_fork_cancel_cgroup
:
2317 spin_unlock(¤t
->sighand
->siglock
);
2318 write_unlock_irq(&tasklist_lock
);
2319 cgroup_cancel_fork(p
, args
);
2321 if (clone_flags
& CLONE_PIDFD
) {
2323 put_unused_fd(pidfd
);
2326 if (pid
!= &init_struct_pid
)
2328 bad_fork_cleanup_thread
:
2330 bad_fork_cleanup_io
:
2333 bad_fork_cleanup_namespaces
:
2334 exit_task_namespaces(p
);
2335 bad_fork_cleanup_mm
:
2337 mm_clear_owner(p
->mm
, p
);
2340 bad_fork_cleanup_signal
:
2341 if (!(clone_flags
& CLONE_THREAD
))
2342 free_signal_struct(p
->signal
);
2343 bad_fork_cleanup_sighand
:
2344 __cleanup_sighand(p
->sighand
);
2345 bad_fork_cleanup_fs
:
2346 exit_fs(p
); /* blocking */
2347 bad_fork_cleanup_files
:
2348 exit_files(p
); /* blocking */
2349 bad_fork_cleanup_semundo
:
2351 bad_fork_cleanup_security
:
2352 security_task_free(p
);
2353 bad_fork_cleanup_audit
:
2355 bad_fork_cleanup_perf
:
2356 perf_event_free_task(p
);
2357 bad_fork_cleanup_policy
:
2358 lockdep_free_task(p
);
2360 mpol_put(p
->mempolicy
);
2361 bad_fork_cleanup_threadgroup_lock
:
2363 delayacct_tsk_free(p
);
2364 bad_fork_cleanup_count
:
2365 atomic_dec(&p
->cred
->user
->processes
);
2368 p
->state
= TASK_DEAD
;
2370 delayed_free_task(p
);
2372 spin_lock_irq(¤t
->sighand
->siglock
);
2373 hlist_del_init(&delayed
.node
);
2374 spin_unlock_irq(¤t
->sighand
->siglock
);
2375 return ERR_PTR(retval
);
2378 static inline void init_idle_pids(struct task_struct
*idle
)
2382 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2383 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2384 init_task_pid(idle
, type
, &init_struct_pid
);
2388 struct task_struct
*fork_idle(int cpu
)
2390 struct task_struct
*task
;
2391 struct kernel_clone_args args
= {
2395 task
= copy_process(&init_struct_pid
, 0, cpu_to_node(cpu
), &args
);
2396 if (!IS_ERR(task
)) {
2397 init_idle_pids(task
);
2398 init_idle(task
, cpu
);
2404 struct mm_struct
*copy_init_mm(void)
2406 return dup_mm(NULL
, &init_mm
);
2410 * Ok, this is the main fork-routine.
2412 * It copies the process, and if successful kick-starts
2413 * it and waits for it to finish using the VM if required.
2415 * args->exit_signal is expected to be checked for sanity by the caller.
2417 long _do_fork(struct kernel_clone_args
*args
)
2419 u64 clone_flags
= args
->flags
;
2420 struct completion vfork
;
2422 struct task_struct
*p
;
2427 * Determine whether and which event to report to ptracer. When
2428 * called from kernel_thread or CLONE_UNTRACED is explicitly
2429 * requested, no event is reported; otherwise, report if the event
2430 * for the type of forking is enabled.
2432 if (!(clone_flags
& CLONE_UNTRACED
)) {
2433 if (clone_flags
& CLONE_VFORK
)
2434 trace
= PTRACE_EVENT_VFORK
;
2435 else if (args
->exit_signal
!= SIGCHLD
)
2436 trace
= PTRACE_EVENT_CLONE
;
2438 trace
= PTRACE_EVENT_FORK
;
2440 if (likely(!ptrace_event_enabled(current
, trace
)))
2444 p
= copy_process(NULL
, trace
, NUMA_NO_NODE
, args
);
2445 add_latent_entropy();
2451 * Do this prior waking up the new thread - the thread pointer
2452 * might get invalid after that point, if the thread exits quickly.
2454 trace_sched_process_fork(current
, p
);
2456 pid
= get_task_pid(p
, PIDTYPE_PID
);
2459 if (clone_flags
& CLONE_PARENT_SETTID
)
2460 put_user(nr
, args
->parent_tid
);
2462 if (clone_flags
& CLONE_VFORK
) {
2463 p
->vfork_done
= &vfork
;
2464 init_completion(&vfork
);
2468 wake_up_new_task(p
);
2470 /* forking complete and child started to run, tell ptracer */
2471 if (unlikely(trace
))
2472 ptrace_event_pid(trace
, pid
);
2474 if (clone_flags
& CLONE_VFORK
) {
2475 if (!wait_for_vfork_done(p
, &vfork
))
2476 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2483 bool legacy_clone_args_valid(const struct kernel_clone_args
*kargs
)
2485 /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
2486 if ((kargs
->flags
& CLONE_PIDFD
) &&
2487 (kargs
->flags
& CLONE_PARENT_SETTID
))
2493 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2494 /* For compatibility with architectures that call do_fork directly rather than
2495 * using the syscall entry points below. */
2496 long do_fork(unsigned long clone_flags
,
2497 unsigned long stack_start
,
2498 unsigned long stack_size
,
2499 int __user
*parent_tidptr
,
2500 int __user
*child_tidptr
)
2502 struct kernel_clone_args args
= {
2503 .flags
= (lower_32_bits(clone_flags
) & ~CSIGNAL
),
2504 .pidfd
= parent_tidptr
,
2505 .child_tid
= child_tidptr
,
2506 .parent_tid
= parent_tidptr
,
2507 .exit_signal
= (lower_32_bits(clone_flags
) & CSIGNAL
),
2508 .stack
= stack_start
,
2509 .stack_size
= stack_size
,
2512 if (!legacy_clone_args_valid(&args
))
2515 return _do_fork(&args
);
2520 * Create a kernel thread.
2522 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2524 struct kernel_clone_args args
= {
2525 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2526 CLONE_UNTRACED
) & ~CSIGNAL
),
2527 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2528 .stack
= (unsigned long)fn
,
2529 .stack_size
= (unsigned long)arg
,
2532 return _do_fork(&args
);
2535 #ifdef __ARCH_WANT_SYS_FORK
2536 SYSCALL_DEFINE0(fork
)
2539 struct kernel_clone_args args
= {
2540 .exit_signal
= SIGCHLD
,
2543 return _do_fork(&args
);
2545 /* can not support in nommu mode */
2551 #ifdef __ARCH_WANT_SYS_VFORK
2552 SYSCALL_DEFINE0(vfork
)
2554 struct kernel_clone_args args
= {
2555 .flags
= CLONE_VFORK
| CLONE_VM
,
2556 .exit_signal
= SIGCHLD
,
2559 return _do_fork(&args
);
2563 #ifdef __ARCH_WANT_SYS_CLONE
2564 #ifdef CONFIG_CLONE_BACKWARDS
2565 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2566 int __user
*, parent_tidptr
,
2568 int __user
*, child_tidptr
)
2569 #elif defined(CONFIG_CLONE_BACKWARDS2)
2570 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2571 int __user
*, parent_tidptr
,
2572 int __user
*, child_tidptr
,
2574 #elif defined(CONFIG_CLONE_BACKWARDS3)
2575 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2577 int __user
*, parent_tidptr
,
2578 int __user
*, child_tidptr
,
2581 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2582 int __user
*, parent_tidptr
,
2583 int __user
*, child_tidptr
,
2587 struct kernel_clone_args args
= {
2588 .flags
= (lower_32_bits(clone_flags
) & ~CSIGNAL
),
2589 .pidfd
= parent_tidptr
,
2590 .child_tid
= child_tidptr
,
2591 .parent_tid
= parent_tidptr
,
2592 .exit_signal
= (lower_32_bits(clone_flags
) & CSIGNAL
),
2597 if (!legacy_clone_args_valid(&args
))
2600 return _do_fork(&args
);
2604 #ifdef __ARCH_WANT_SYS_CLONE3
2607 * copy_thread implementations handle CLONE_SETTLS by reading the TLS value from
2608 * the registers containing the syscall arguments for clone. This doesn't work
2609 * with clone3 since the TLS value is passed in clone_args instead.
2611 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2612 #error clone3 requires copy_thread_tls support in arch
2615 noinline
static int copy_clone_args_from_user(struct kernel_clone_args
*kargs
,
2616 struct clone_args __user
*uargs
,
2620 struct clone_args args
;
2621 pid_t
*kset_tid
= kargs
->set_tid
;
2623 BUILD_BUG_ON(offsetofend(struct clone_args
, tls
) !=
2624 CLONE_ARGS_SIZE_VER0
);
2625 BUILD_BUG_ON(offsetofend(struct clone_args
, set_tid_size
) !=
2626 CLONE_ARGS_SIZE_VER1
);
2627 BUILD_BUG_ON(offsetofend(struct clone_args
, cgroup
) !=
2628 CLONE_ARGS_SIZE_VER2
);
2629 BUILD_BUG_ON(sizeof(struct clone_args
) != CLONE_ARGS_SIZE_VER2
);
2631 if (unlikely(usize
> PAGE_SIZE
))
2633 if (unlikely(usize
< CLONE_ARGS_SIZE_VER0
))
2636 err
= copy_struct_from_user(&args
, sizeof(args
), uargs
, usize
);
2640 if (unlikely(args
.set_tid_size
> MAX_PID_NS_LEVEL
))
2643 if (unlikely(!args
.set_tid
&& args
.set_tid_size
> 0))
2646 if (unlikely(args
.set_tid
&& args
.set_tid_size
== 0))
2650 * Verify that higher 32bits of exit_signal are unset and that
2651 * it is a valid signal
2653 if (unlikely((args
.exit_signal
& ~((u64
)CSIGNAL
)) ||
2654 !valid_signal(args
.exit_signal
)))
2657 if ((args
.flags
& CLONE_INTO_CGROUP
) &&
2658 (args
.cgroup
> INT_MAX
|| usize
< CLONE_ARGS_SIZE_VER2
))
2661 *kargs
= (struct kernel_clone_args
){
2662 .flags
= args
.flags
,
2663 .pidfd
= u64_to_user_ptr(args
.pidfd
),
2664 .child_tid
= u64_to_user_ptr(args
.child_tid
),
2665 .parent_tid
= u64_to_user_ptr(args
.parent_tid
),
2666 .exit_signal
= args
.exit_signal
,
2667 .stack
= args
.stack
,
2668 .stack_size
= args
.stack_size
,
2670 .set_tid_size
= args
.set_tid_size
,
2671 .cgroup
= args
.cgroup
,
2675 copy_from_user(kset_tid
, u64_to_user_ptr(args
.set_tid
),
2676 (kargs
->set_tid_size
* sizeof(pid_t
))))
2679 kargs
->set_tid
= kset_tid
;
2685 * clone3_stack_valid - check and prepare stack
2686 * @kargs: kernel clone args
2688 * Verify that the stack arguments userspace gave us are sane.
2689 * In addition, set the stack direction for userspace since it's easy for us to
2692 static inline bool clone3_stack_valid(struct kernel_clone_args
*kargs
)
2694 if (kargs
->stack
== 0) {
2695 if (kargs
->stack_size
> 0)
2698 if (kargs
->stack_size
== 0)
2701 if (!access_ok((void __user
*)kargs
->stack
, kargs
->stack_size
))
2704 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
2705 kargs
->stack
+= kargs
->stack_size
;
2712 static bool clone3_args_valid(struct kernel_clone_args
*kargs
)
2714 /* Verify that no unknown flags are passed along. */
2716 ~(CLONE_LEGACY_FLAGS
| CLONE_CLEAR_SIGHAND
| CLONE_INTO_CGROUP
))
2720 * - make the CLONE_DETACHED bit reuseable for clone3
2721 * - make the CSIGNAL bits reuseable for clone3
2723 if (kargs
->flags
& (CLONE_DETACHED
| CSIGNAL
))
2726 if ((kargs
->flags
& (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
)) ==
2727 (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
))
2730 if ((kargs
->flags
& (CLONE_THREAD
| CLONE_PARENT
)) &&
2734 if (!clone3_stack_valid(kargs
))
2741 * clone3 - create a new process with specific properties
2742 * @uargs: argument structure
2743 * @size: size of @uargs
2745 * clone3() is the extensible successor to clone()/clone2().
2746 * It takes a struct as argument that is versioned by its size.
2748 * Return: On success, a positive PID for the child process.
2749 * On error, a negative errno number.
2751 SYSCALL_DEFINE2(clone3
, struct clone_args __user
*, uargs
, size_t, size
)
2755 struct kernel_clone_args kargs
;
2756 pid_t set_tid
[MAX_PID_NS_LEVEL
];
2758 kargs
.set_tid
= set_tid
;
2760 err
= copy_clone_args_from_user(&kargs
, uargs
, size
);
2764 if (!clone3_args_valid(&kargs
))
2767 return _do_fork(&kargs
);
2771 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2773 struct task_struct
*leader
, *parent
, *child
;
2776 read_lock(&tasklist_lock
);
2777 leader
= top
= top
->group_leader
;
2779 for_each_thread(leader
, parent
) {
2780 list_for_each_entry(child
, &parent
->children
, sibling
) {
2781 res
= visitor(child
, data
);
2793 if (leader
!= top
) {
2795 parent
= child
->real_parent
;
2796 leader
= parent
->group_leader
;
2800 read_unlock(&tasklist_lock
);
2803 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2804 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2807 static void sighand_ctor(void *data
)
2809 struct sighand_struct
*sighand
= data
;
2811 spin_lock_init(&sighand
->siglock
);
2812 init_waitqueue_head(&sighand
->signalfd_wqh
);
2815 void __init
proc_caches_init(void)
2817 unsigned int mm_size
;
2819 sighand_cachep
= kmem_cache_create("sighand_cache",
2820 sizeof(struct sighand_struct
), 0,
2821 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
2822 SLAB_ACCOUNT
, sighand_ctor
);
2823 signal_cachep
= kmem_cache_create("signal_cache",
2824 sizeof(struct signal_struct
), 0,
2825 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2827 files_cachep
= kmem_cache_create("files_cache",
2828 sizeof(struct files_struct
), 0,
2829 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2831 fs_cachep
= kmem_cache_create("fs_cache",
2832 sizeof(struct fs_struct
), 0,
2833 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2837 * The mm_cpumask is located at the end of mm_struct, and is
2838 * dynamically sized based on the maximum CPU number this system
2839 * can have, taking hotplug into account (nr_cpu_ids).
2841 mm_size
= sizeof(struct mm_struct
) + cpumask_size();
2843 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
2844 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
2845 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2846 offsetof(struct mm_struct
, saved_auxv
),
2847 sizeof_field(struct mm_struct
, saved_auxv
),
2849 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2851 nsproxy_cache_init();
2855 * Check constraints on flags passed to the unshare system call.
2857 static int check_unshare_flags(unsigned long unshare_flags
)
2859 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2860 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2861 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2862 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
|
2866 * Not implemented, but pretend it works if there is nothing
2867 * to unshare. Note that unsharing the address space or the
2868 * signal handlers also need to unshare the signal queues (aka
2871 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2872 if (!thread_group_empty(current
))
2875 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2876 if (refcount_read(¤t
->sighand
->count
) > 1)
2879 if (unshare_flags
& CLONE_VM
) {
2880 if (!current_is_single_threaded())
2888 * Unshare the filesystem structure if it is being shared
2890 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2892 struct fs_struct
*fs
= current
->fs
;
2894 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2897 /* don't need lock here; in the worst case we'll do useless copy */
2901 *new_fsp
= copy_fs_struct(fs
);
2909 * Unshare file descriptor table if it is being shared
2911 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2913 struct files_struct
*fd
= current
->files
;
2916 if ((unshare_flags
& CLONE_FILES
) &&
2917 (fd
&& atomic_read(&fd
->count
) > 1)) {
2918 *new_fdp
= dup_fd(fd
, &error
);
2927 * unshare allows a process to 'unshare' part of the process
2928 * context which was originally shared using clone. copy_*
2929 * functions used by do_fork() cannot be used here directly
2930 * because they modify an inactive task_struct that is being
2931 * constructed. Here we are modifying the current, active,
2934 int ksys_unshare(unsigned long unshare_flags
)
2936 struct fs_struct
*fs
, *new_fs
= NULL
;
2937 struct files_struct
*fd
, *new_fd
= NULL
;
2938 struct cred
*new_cred
= NULL
;
2939 struct nsproxy
*new_nsproxy
= NULL
;
2944 * If unsharing a user namespace must also unshare the thread group
2945 * and unshare the filesystem root and working directories.
2947 if (unshare_flags
& CLONE_NEWUSER
)
2948 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2950 * If unsharing vm, must also unshare signal handlers.
2952 if (unshare_flags
& CLONE_VM
)
2953 unshare_flags
|= CLONE_SIGHAND
;
2955 * If unsharing a signal handlers, must also unshare the signal queues.
2957 if (unshare_flags
& CLONE_SIGHAND
)
2958 unshare_flags
|= CLONE_THREAD
;
2960 * If unsharing namespace, must also unshare filesystem information.
2962 if (unshare_flags
& CLONE_NEWNS
)
2963 unshare_flags
|= CLONE_FS
;
2965 err
= check_unshare_flags(unshare_flags
);
2967 goto bad_unshare_out
;
2969 * CLONE_NEWIPC must also detach from the undolist: after switching
2970 * to a new ipc namespace, the semaphore arrays from the old
2971 * namespace are unreachable.
2973 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2975 err
= unshare_fs(unshare_flags
, &new_fs
);
2977 goto bad_unshare_out
;
2978 err
= unshare_fd(unshare_flags
, &new_fd
);
2980 goto bad_unshare_cleanup_fs
;
2981 err
= unshare_userns(unshare_flags
, &new_cred
);
2983 goto bad_unshare_cleanup_fd
;
2984 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2987 goto bad_unshare_cleanup_cred
;
2989 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2992 * CLONE_SYSVSEM is equivalent to sys_exit().
2996 if (unshare_flags
& CLONE_NEWIPC
) {
2997 /* Orphan segments in old ns (see sem above). */
2999 shm_init_task(current
);
3003 switch_task_namespaces(current
, new_nsproxy
);
3009 spin_lock(&fs
->lock
);
3010 current
->fs
= new_fs
;
3015 spin_unlock(&fs
->lock
);
3019 fd
= current
->files
;
3020 current
->files
= new_fd
;
3024 task_unlock(current
);
3027 /* Install the new user namespace */
3028 commit_creds(new_cred
);
3033 perf_event_namespaces(current
);
3035 bad_unshare_cleanup_cred
:
3038 bad_unshare_cleanup_fd
:
3040 put_files_struct(new_fd
);
3042 bad_unshare_cleanup_fs
:
3044 free_fs_struct(new_fs
);
3050 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
3052 return ksys_unshare(unshare_flags
);
3056 * Helper to unshare the files of the current task.
3057 * We don't want to expose copy_files internals to
3058 * the exec layer of the kernel.
3061 int unshare_files(struct files_struct
**displaced
)
3063 struct task_struct
*task
= current
;
3064 struct files_struct
*copy
= NULL
;
3067 error
= unshare_fd(CLONE_FILES
, ©
);
3068 if (error
|| !copy
) {
3072 *displaced
= task
->files
;
3079 int sysctl_max_threads(struct ctl_table
*table
, int write
,
3080 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
3084 int threads
= max_threads
;
3086 int max
= MAX_THREADS
;
3093 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
3097 max_threads
= threads
;