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>
43 #include <linux/hmm.h>
46 #include <linux/vmacache.h>
47 #include <linux/nsproxy.h>
48 #include <linux/capability.h>
49 #include <linux/cpu.h>
50 #include <linux/cgroup.h>
51 #include <linux/security.h>
52 #include <linux/hugetlb.h>
53 #include <linux/seccomp.h>
54 #include <linux/swap.h>
55 #include <linux/syscalls.h>
56 #include <linux/jiffies.h>
57 #include <linux/futex.h>
58 #include <linux/compat.h>
59 #include <linux/kthread.h>
60 #include <linux/task_io_accounting_ops.h>
61 #include <linux/rcupdate.h>
62 #include <linux/ptrace.h>
63 #include <linux/mount.h>
64 #include <linux/audit.h>
65 #include <linux/memcontrol.h>
66 #include <linux/ftrace.h>
67 #include <linux/proc_fs.h>
68 #include <linux/profile.h>
69 #include <linux/rmap.h>
70 #include <linux/ksm.h>
71 #include <linux/acct.h>
72 #include <linux/userfaultfd_k.h>
73 #include <linux/tsacct_kern.h>
74 #include <linux/cn_proc.h>
75 #include <linux/freezer.h>
76 #include <linux/delayacct.h>
77 #include <linux/taskstats_kern.h>
78 #include <linux/random.h>
79 #include <linux/tty.h>
80 #include <linux/blkdev.h>
81 #include <linux/fs_struct.h>
82 #include <linux/magic.h>
83 #include <linux/perf_event.h>
84 #include <linux/posix-timers.h>
85 #include <linux/user-return-notifier.h>
86 #include <linux/oom.h>
87 #include <linux/khugepaged.h>
88 #include <linux/signalfd.h>
89 #include <linux/uprobes.h>
90 #include <linux/aio.h>
91 #include <linux/compiler.h>
92 #include <linux/sysctl.h>
93 #include <linux/kcov.h>
94 #include <linux/livepatch.h>
95 #include <linux/thread_info.h>
96 #include <linux/stackleak.h>
98 #include <asm/pgtable.h>
99 #include <asm/pgalloc.h>
100 #include <linux/uaccess.h>
101 #include <asm/mmu_context.h>
102 #include <asm/cacheflush.h>
103 #include <asm/tlbflush.h>
105 #include <trace/events/sched.h>
107 #define CREATE_TRACE_POINTS
108 #include <trace/events/task.h>
111 * Minimum number of threads to boot the kernel
113 #define MIN_THREADS 20
116 * Maximum number of threads
118 #define MAX_THREADS FUTEX_TID_MASK
121 * Protected counters by write_lock_irq(&tasklist_lock)
123 unsigned long total_forks
; /* Handle normal Linux uptimes. */
124 int nr_threads
; /* The idle threads do not count.. */
126 static int max_threads
; /* tunable limit on nr_threads */
128 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
130 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
132 #ifdef CONFIG_PROVE_RCU
133 int lockdep_tasklist_lock_is_held(void)
135 return lockdep_is_held(&tasklist_lock
);
137 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
138 #endif /* #ifdef CONFIG_PROVE_RCU */
140 int nr_processes(void)
145 for_each_possible_cpu(cpu
)
146 total
+= per_cpu(process_counts
, cpu
);
151 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
155 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
156 static struct kmem_cache
*task_struct_cachep
;
158 static inline struct task_struct
*alloc_task_struct_node(int node
)
160 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
163 static inline void free_task_struct(struct task_struct
*tsk
)
165 kmem_cache_free(task_struct_cachep
, tsk
);
169 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
172 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
173 * kmemcache based allocator.
175 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
177 #ifdef CONFIG_VMAP_STACK
179 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
180 * flush. Try to minimize the number of calls by caching stacks.
182 #define NR_CACHED_STACKS 2
183 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
185 static int free_vm_stack_cache(unsigned int cpu
)
187 struct vm_struct
**cached_vm_stacks
= per_cpu_ptr(cached_stacks
, cpu
);
190 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
191 struct vm_struct
*vm_stack
= cached_vm_stacks
[i
];
196 vfree(vm_stack
->addr
);
197 cached_vm_stacks
[i
] = NULL
;
204 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
206 #ifdef CONFIG_VMAP_STACK
210 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
213 s
= this_cpu_xchg(cached_stacks
[i
], NULL
);
218 /* Clear stale pointers from reused stack. */
219 memset(s
->addr
, 0, THREAD_SIZE
);
221 tsk
->stack_vm_area
= s
;
222 tsk
->stack
= s
->addr
;
227 * Allocated stacks are cached and later reused by new threads,
228 * so memcg accounting is performed manually on assigning/releasing
229 * stacks to tasks. Drop __GFP_ACCOUNT.
231 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_ALIGN
,
232 VMALLOC_START
, VMALLOC_END
,
233 THREADINFO_GFP
& ~__GFP_ACCOUNT
,
235 0, node
, __builtin_return_address(0));
238 * We can't call find_vm_area() in interrupt context, and
239 * free_thread_stack() can be called in interrupt context,
240 * so cache the vm_struct.
243 tsk
->stack_vm_area
= find_vm_area(stack
);
248 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
252 tsk
->stack
= page_address(page
);
259 static inline void free_thread_stack(struct task_struct
*tsk
)
261 #ifdef CONFIG_VMAP_STACK
262 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
267 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
268 mod_memcg_page_state(vm
->pages
[i
],
269 MEMCG_KERNEL_STACK_KB
,
270 -(int)(PAGE_SIZE
/ 1024));
272 memcg_kmem_uncharge(vm
->pages
[i
], 0);
275 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
276 if (this_cpu_cmpxchg(cached_stacks
[i
],
277 NULL
, tsk
->stack_vm_area
) != NULL
)
283 vfree_atomic(tsk
->stack
);
288 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
291 static struct kmem_cache
*thread_stack_cache
;
293 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
296 unsigned long *stack
;
297 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
302 static void free_thread_stack(struct task_struct
*tsk
)
304 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
307 void thread_stack_cache_init(void)
309 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
310 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
312 BUG_ON(thread_stack_cache
== NULL
);
317 /* SLAB cache for signal_struct structures (tsk->signal) */
318 static struct kmem_cache
*signal_cachep
;
320 /* SLAB cache for sighand_struct structures (tsk->sighand) */
321 struct kmem_cache
*sighand_cachep
;
323 /* SLAB cache for files_struct structures (tsk->files) */
324 struct kmem_cache
*files_cachep
;
326 /* SLAB cache for fs_struct structures (tsk->fs) */
327 struct kmem_cache
*fs_cachep
;
329 /* SLAB cache for vm_area_struct structures */
330 static struct kmem_cache
*vm_area_cachep
;
332 /* SLAB cache for mm_struct structures (tsk->mm) */
333 static struct kmem_cache
*mm_cachep
;
335 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
337 struct vm_area_struct
*vma
;
339 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
345 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
347 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
351 INIT_LIST_HEAD(&new->anon_vma_chain
);
356 void vm_area_free(struct vm_area_struct
*vma
)
358 kmem_cache_free(vm_area_cachep
, vma
);
361 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
363 void *stack
= task_stack_page(tsk
);
364 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
366 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
371 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
373 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
374 mod_zone_page_state(page_zone(vm
->pages
[i
]),
376 PAGE_SIZE
/ 1024 * account
);
380 * All stack pages are in the same zone and belong to the
383 struct page
*first_page
= virt_to_page(stack
);
385 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
386 THREAD_SIZE
/ 1024 * account
);
388 mod_memcg_page_state(first_page
, MEMCG_KERNEL_STACK_KB
,
389 account
* (THREAD_SIZE
/ 1024));
393 static int memcg_charge_kernel_stack(struct task_struct
*tsk
)
395 #ifdef CONFIG_VMAP_STACK
396 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
402 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
404 * If memcg_kmem_charge() fails, page->mem_cgroup
405 * pointer is NULL, and both memcg_kmem_uncharge()
406 * and mod_memcg_page_state() in free_thread_stack()
407 * will ignore this page. So it's safe.
409 ret
= memcg_kmem_charge(vm
->pages
[i
], GFP_KERNEL
, 0);
413 mod_memcg_page_state(vm
->pages
[i
],
414 MEMCG_KERNEL_STACK_KB
,
422 static void release_task_stack(struct task_struct
*tsk
)
424 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
425 return; /* Better to leak the stack than to free prematurely */
427 account_kernel_stack(tsk
, -1);
428 free_thread_stack(tsk
);
430 #ifdef CONFIG_VMAP_STACK
431 tsk
->stack_vm_area
= NULL
;
435 #ifdef CONFIG_THREAD_INFO_IN_TASK
436 void put_task_stack(struct task_struct
*tsk
)
438 if (refcount_dec_and_test(&tsk
->stack_refcount
))
439 release_task_stack(tsk
);
443 void free_task(struct task_struct
*tsk
)
445 #ifndef CONFIG_THREAD_INFO_IN_TASK
447 * The task is finally done with both the stack and thread_info,
450 release_task_stack(tsk
);
453 * If the task had a separate stack allocation, it should be gone
456 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
458 rt_mutex_debug_task_free(tsk
);
459 ftrace_graph_exit_task(tsk
);
460 put_seccomp_filter(tsk
);
461 arch_release_task_struct(tsk
);
462 if (tsk
->flags
& PF_KTHREAD
)
463 free_kthread_struct(tsk
);
464 free_task_struct(tsk
);
466 EXPORT_SYMBOL(free_task
);
469 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
470 struct mm_struct
*oldmm
)
472 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
473 struct rb_node
**rb_link
, *rb_parent
;
475 unsigned long charge
;
478 uprobe_start_dup_mmap();
479 if (down_write_killable(&oldmm
->mmap_sem
)) {
481 goto fail_uprobe_end
;
483 flush_cache_dup_mm(oldmm
);
484 uprobe_dup_mmap(oldmm
, mm
);
486 * Not linked in yet - no deadlock potential:
488 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
490 /* No ordering required: file already has been exposed. */
491 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
493 mm
->total_vm
= oldmm
->total_vm
;
494 mm
->data_vm
= oldmm
->data_vm
;
495 mm
->exec_vm
= oldmm
->exec_vm
;
496 mm
->stack_vm
= oldmm
->stack_vm
;
498 rb_link
= &mm
->mm_rb
.rb_node
;
501 retval
= ksm_fork(mm
, oldmm
);
504 retval
= khugepaged_fork(mm
, oldmm
);
509 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
512 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
513 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
518 * Don't duplicate many vmas if we've been oom-killed (for
521 if (fatal_signal_pending(current
)) {
525 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
526 unsigned long len
= vma_pages(mpnt
);
528 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
532 tmp
= vm_area_dup(mpnt
);
535 retval
= vma_dup_policy(mpnt
, tmp
);
537 goto fail_nomem_policy
;
539 retval
= dup_userfaultfd(tmp
, &uf
);
541 goto fail_nomem_anon_vma_fork
;
542 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
543 /* VM_WIPEONFORK gets a clean slate in the child. */
544 tmp
->anon_vma
= NULL
;
545 if (anon_vma_prepare(tmp
))
546 goto fail_nomem_anon_vma_fork
;
547 } else if (anon_vma_fork(tmp
, mpnt
))
548 goto fail_nomem_anon_vma_fork
;
549 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
550 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
553 struct inode
*inode
= file_inode(file
);
554 struct address_space
*mapping
= file
->f_mapping
;
557 if (tmp
->vm_flags
& VM_DENYWRITE
)
558 atomic_dec(&inode
->i_writecount
);
559 i_mmap_lock_write(mapping
);
560 if (tmp
->vm_flags
& VM_SHARED
)
561 atomic_inc(&mapping
->i_mmap_writable
);
562 flush_dcache_mmap_lock(mapping
);
563 /* insert tmp into the share list, just after mpnt */
564 vma_interval_tree_insert_after(tmp
, mpnt
,
566 flush_dcache_mmap_unlock(mapping
);
567 i_mmap_unlock_write(mapping
);
571 * Clear hugetlb-related page reserves for children. This only
572 * affects MAP_PRIVATE mappings. Faults generated by the child
573 * are not guaranteed to succeed, even if read-only
575 if (is_vm_hugetlb_page(tmp
))
576 reset_vma_resv_huge_pages(tmp
);
579 * Link in the new vma and copy the page table entries.
582 pprev
= &tmp
->vm_next
;
586 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
587 rb_link
= &tmp
->vm_rb
.rb_right
;
588 rb_parent
= &tmp
->vm_rb
;
591 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
592 retval
= copy_page_range(mm
, oldmm
, mpnt
);
594 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
595 tmp
->vm_ops
->open(tmp
);
600 /* a new mm has just been created */
601 retval
= arch_dup_mmap(oldmm
, mm
);
603 up_write(&mm
->mmap_sem
);
605 up_write(&oldmm
->mmap_sem
);
606 dup_userfaultfd_complete(&uf
);
608 uprobe_end_dup_mmap();
610 fail_nomem_anon_vma_fork
:
611 mpol_put(vma_policy(tmp
));
616 vm_unacct_memory(charge
);
620 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
622 mm
->pgd
= pgd_alloc(mm
);
623 if (unlikely(!mm
->pgd
))
628 static inline void mm_free_pgd(struct mm_struct
*mm
)
630 pgd_free(mm
, mm
->pgd
);
633 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
635 down_write(&oldmm
->mmap_sem
);
636 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
637 up_write(&oldmm
->mmap_sem
);
640 #define mm_alloc_pgd(mm) (0)
641 #define mm_free_pgd(mm)
642 #endif /* CONFIG_MMU */
644 static void check_mm(struct mm_struct
*mm
)
648 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
649 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
652 printk(KERN_ALERT
"BUG: Bad rss-counter state "
653 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
656 if (mm_pgtables_bytes(mm
))
657 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
658 mm_pgtables_bytes(mm
));
660 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
661 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
665 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
666 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
669 * Called when the last reference to the mm
670 * is dropped: either by a lazy thread or by
671 * mmput. Free the page directory and the mm.
673 void __mmdrop(struct mm_struct
*mm
)
675 BUG_ON(mm
== &init_mm
);
676 WARN_ON_ONCE(mm
== current
->mm
);
677 WARN_ON_ONCE(mm
== current
->active_mm
);
680 mmu_notifier_mm_destroy(mm
);
682 put_user_ns(mm
->user_ns
);
685 EXPORT_SYMBOL_GPL(__mmdrop
);
687 static void mmdrop_async_fn(struct work_struct
*work
)
689 struct mm_struct
*mm
;
691 mm
= container_of(work
, struct mm_struct
, async_put_work
);
695 static void mmdrop_async(struct mm_struct
*mm
)
697 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
698 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
699 schedule_work(&mm
->async_put_work
);
703 static inline void free_signal_struct(struct signal_struct
*sig
)
705 taskstats_tgid_free(sig
);
706 sched_autogroup_exit(sig
);
708 * __mmdrop is not safe to call from softirq context on x86 due to
709 * pgd_dtor so postpone it to the async context
712 mmdrop_async(sig
->oom_mm
);
713 kmem_cache_free(signal_cachep
, sig
);
716 static inline void put_signal_struct(struct signal_struct
*sig
)
718 if (refcount_dec_and_test(&sig
->sigcnt
))
719 free_signal_struct(sig
);
722 void __put_task_struct(struct task_struct
*tsk
)
724 WARN_ON(!tsk
->exit_state
);
725 WARN_ON(refcount_read(&tsk
->usage
));
726 WARN_ON(tsk
== current
);
729 task_numa_free(tsk
, true);
730 security_task_free(tsk
);
732 delayacct_tsk_free(tsk
);
733 put_signal_struct(tsk
->signal
);
735 if (!profile_handoff_task(tsk
))
738 EXPORT_SYMBOL_GPL(__put_task_struct
);
740 void __init __weak
arch_task_cache_init(void) { }
745 static void set_max_threads(unsigned int max_threads_suggested
)
748 unsigned long nr_pages
= totalram_pages();
751 * The number of threads shall be limited such that the thread
752 * structures may only consume a small part of the available memory.
754 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
755 threads
= MAX_THREADS
;
757 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
758 (u64
) THREAD_SIZE
* 8UL);
760 if (threads
> max_threads_suggested
)
761 threads
= max_threads_suggested
;
763 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
766 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
767 /* Initialized by the architecture: */
768 int arch_task_struct_size __read_mostly
;
771 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
772 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
774 /* Fetch thread_struct whitelist for the architecture. */
775 arch_thread_struct_whitelist(offset
, size
);
778 * Handle zero-sized whitelist or empty thread_struct, otherwise
779 * adjust offset to position of thread_struct in task_struct.
781 if (unlikely(*size
== 0))
784 *offset
+= offsetof(struct task_struct
, thread
);
786 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
788 void __init
fork_init(void)
791 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
792 #ifndef ARCH_MIN_TASKALIGN
793 #define ARCH_MIN_TASKALIGN 0
795 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
796 unsigned long useroffset
, usersize
;
798 /* create a slab on which task_structs can be allocated */
799 task_struct_whitelist(&useroffset
, &usersize
);
800 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
801 arch_task_struct_size
, align
,
802 SLAB_PANIC
|SLAB_ACCOUNT
,
803 useroffset
, usersize
, NULL
);
806 /* do the arch specific task caches init */
807 arch_task_cache_init();
809 set_max_threads(MAX_THREADS
);
811 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
812 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
813 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
814 init_task
.signal
->rlim
[RLIMIT_NPROC
];
816 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
817 init_user_ns
.ucount_max
[i
] = max_threads
/2;
820 #ifdef CONFIG_VMAP_STACK
821 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
822 NULL
, free_vm_stack_cache
);
825 lockdep_init_task(&init_task
);
829 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
830 struct task_struct
*src
)
836 void set_task_stack_end_magic(struct task_struct
*tsk
)
838 unsigned long *stackend
;
840 stackend
= end_of_stack(tsk
);
841 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
844 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
846 struct task_struct
*tsk
;
847 unsigned long *stack
;
848 struct vm_struct
*stack_vm_area __maybe_unused
;
851 if (node
== NUMA_NO_NODE
)
852 node
= tsk_fork_get_node(orig
);
853 tsk
= alloc_task_struct_node(node
);
857 stack
= alloc_thread_stack_node(tsk
, node
);
861 if (memcg_charge_kernel_stack(tsk
))
864 stack_vm_area
= task_stack_vm_area(tsk
);
866 err
= arch_dup_task_struct(tsk
, orig
);
869 * arch_dup_task_struct() clobbers the stack-related fields. Make
870 * sure they're properly initialized before using any stack-related
874 #ifdef CONFIG_VMAP_STACK
875 tsk
->stack_vm_area
= stack_vm_area
;
877 #ifdef CONFIG_THREAD_INFO_IN_TASK
878 refcount_set(&tsk
->stack_refcount
, 1);
884 #ifdef CONFIG_SECCOMP
886 * We must handle setting up seccomp filters once we're under
887 * the sighand lock in case orig has changed between now and
888 * then. Until then, filter must be NULL to avoid messing up
889 * the usage counts on the error path calling free_task.
891 tsk
->seccomp
.filter
= NULL
;
894 setup_thread_stack(tsk
, orig
);
895 clear_user_return_notifier(tsk
);
896 clear_tsk_need_resched(tsk
);
897 set_task_stack_end_magic(tsk
);
899 #ifdef CONFIG_STACKPROTECTOR
900 tsk
->stack_canary
= get_random_canary();
902 if (orig
->cpus_ptr
== &orig
->cpus_mask
)
903 tsk
->cpus_ptr
= &tsk
->cpus_mask
;
906 * One for us, one for whoever does the "release_task()" (usually
909 refcount_set(&tsk
->usage
, 2);
910 #ifdef CONFIG_BLK_DEV_IO_TRACE
913 tsk
->splice_pipe
= NULL
;
914 tsk
->task_frag
.page
= NULL
;
915 tsk
->wake_q
.next
= NULL
;
917 account_kernel_stack(tsk
, 1);
921 #ifdef CONFIG_FAULT_INJECTION
925 #ifdef CONFIG_BLK_CGROUP
926 tsk
->throttle_queue
= NULL
;
927 tsk
->use_memdelay
= 0;
931 tsk
->active_memcg
= NULL
;
936 free_thread_stack(tsk
);
938 free_task_struct(tsk
);
942 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
944 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
946 static int __init
coredump_filter_setup(char *s
)
948 default_dump_filter
=
949 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
950 MMF_DUMP_FILTER_MASK
;
954 __setup("coredump_filter=", coredump_filter_setup
);
956 #include <linux/init_task.h>
958 static void mm_init_aio(struct mm_struct
*mm
)
961 spin_lock_init(&mm
->ioctx_lock
);
962 mm
->ioctx_table
= NULL
;
966 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
967 struct task_struct
*p
)
971 WRITE_ONCE(mm
->owner
, NULL
);
975 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
982 static void mm_init_uprobes_state(struct mm_struct
*mm
)
984 #ifdef CONFIG_UPROBES
985 mm
->uprobes_state
.xol_area
= NULL
;
989 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
990 struct user_namespace
*user_ns
)
994 mm
->vmacache_seqnum
= 0;
995 atomic_set(&mm
->mm_users
, 1);
996 atomic_set(&mm
->mm_count
, 1);
997 init_rwsem(&mm
->mmap_sem
);
998 INIT_LIST_HEAD(&mm
->mmlist
);
999 mm
->core_state
= NULL
;
1000 mm_pgtables_bytes_init(mm
);
1003 atomic64_set(&mm
->pinned_vm
, 0);
1004 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
1005 spin_lock_init(&mm
->page_table_lock
);
1006 spin_lock_init(&mm
->arg_lock
);
1007 mm_init_cpumask(mm
);
1009 mm_init_owner(mm
, p
);
1010 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1011 mmu_notifier_mm_init(mm
);
1013 init_tlb_flush_pending(mm
);
1014 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1015 mm
->pmd_huge_pte
= NULL
;
1017 mm_init_uprobes_state(mm
);
1020 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1021 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1023 mm
->flags
= default_dump_filter
;
1027 if (mm_alloc_pgd(mm
))
1030 if (init_new_context(p
, mm
))
1031 goto fail_nocontext
;
1033 mm
->user_ns
= get_user_ns(user_ns
);
1044 * Allocate and initialize an mm_struct.
1046 struct mm_struct
*mm_alloc(void)
1048 struct mm_struct
*mm
;
1054 memset(mm
, 0, sizeof(*mm
));
1055 return mm_init(mm
, current
, current_user_ns());
1058 static inline void __mmput(struct mm_struct
*mm
)
1060 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1062 uprobe_clear_state(mm
);
1065 khugepaged_exit(mm
); /* must run before exit_mmap */
1067 mm_put_huge_zero_page(mm
);
1068 set_mm_exe_file(mm
, NULL
);
1069 if (!list_empty(&mm
->mmlist
)) {
1070 spin_lock(&mmlist_lock
);
1071 list_del(&mm
->mmlist
);
1072 spin_unlock(&mmlist_lock
);
1075 module_put(mm
->binfmt
->module
);
1080 * Decrement the use count and release all resources for an mm.
1082 void mmput(struct mm_struct
*mm
)
1086 if (atomic_dec_and_test(&mm
->mm_users
))
1089 EXPORT_SYMBOL_GPL(mmput
);
1092 static void mmput_async_fn(struct work_struct
*work
)
1094 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1100 void mmput_async(struct mm_struct
*mm
)
1102 if (atomic_dec_and_test(&mm
->mm_users
)) {
1103 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1104 schedule_work(&mm
->async_put_work
);
1110 * set_mm_exe_file - change a reference to the mm's executable file
1112 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1114 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1115 * invocations: in mmput() nobody alive left, in execve task is single
1116 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1117 * mm->exe_file, but does so without using set_mm_exe_file() in order
1118 * to do avoid the need for any locks.
1120 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1122 struct file
*old_exe_file
;
1125 * It is safe to dereference the exe_file without RCU as
1126 * this function is only called if nobody else can access
1127 * this mm -- see comment above for justification.
1129 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1132 get_file(new_exe_file
);
1133 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1139 * get_mm_exe_file - acquire a reference to the mm's executable file
1141 * Returns %NULL if mm has no associated executable file.
1142 * User must release file via fput().
1144 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1146 struct file
*exe_file
;
1149 exe_file
= rcu_dereference(mm
->exe_file
);
1150 if (exe_file
&& !get_file_rcu(exe_file
))
1155 EXPORT_SYMBOL(get_mm_exe_file
);
1158 * get_task_exe_file - acquire a reference to the task's executable file
1160 * Returns %NULL if task's mm (if any) has no associated executable file or
1161 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1162 * User must release file via fput().
1164 struct file
*get_task_exe_file(struct task_struct
*task
)
1166 struct file
*exe_file
= NULL
;
1167 struct mm_struct
*mm
;
1172 if (!(task
->flags
& PF_KTHREAD
))
1173 exe_file
= get_mm_exe_file(mm
);
1178 EXPORT_SYMBOL(get_task_exe_file
);
1181 * get_task_mm - acquire a reference to the task's mm
1183 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1184 * this kernel workthread has transiently adopted a user mm with use_mm,
1185 * to do its AIO) is not set and if so returns a reference to it, after
1186 * bumping up the use count. User must release the mm via mmput()
1187 * after use. Typically used by /proc and ptrace.
1189 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1191 struct mm_struct
*mm
;
1196 if (task
->flags
& PF_KTHREAD
)
1204 EXPORT_SYMBOL_GPL(get_task_mm
);
1206 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1208 struct mm_struct
*mm
;
1211 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
1213 return ERR_PTR(err
);
1215 mm
= get_task_mm(task
);
1216 if (mm
&& mm
!= current
->mm
&&
1217 !ptrace_may_access(task
, mode
)) {
1219 mm
= ERR_PTR(-EACCES
);
1221 mutex_unlock(&task
->signal
->cred_guard_mutex
);
1226 static void complete_vfork_done(struct task_struct
*tsk
)
1228 struct completion
*vfork
;
1231 vfork
= tsk
->vfork_done
;
1232 if (likely(vfork
)) {
1233 tsk
->vfork_done
= NULL
;
1239 static int wait_for_vfork_done(struct task_struct
*child
,
1240 struct completion
*vfork
)
1244 freezer_do_not_count();
1245 cgroup_enter_frozen();
1246 killed
= wait_for_completion_killable(vfork
);
1247 cgroup_leave_frozen(false);
1252 child
->vfork_done
= NULL
;
1256 put_task_struct(child
);
1260 /* Please note the differences between mmput and mm_release.
1261 * mmput is called whenever we stop holding onto a mm_struct,
1262 * error success whatever.
1264 * mm_release is called after a mm_struct has been removed
1265 * from the current process.
1267 * This difference is important for error handling, when we
1268 * only half set up a mm_struct for a new process and need to restore
1269 * the old one. Because we mmput the new mm_struct before
1270 * restoring the old one. . .
1271 * Eric Biederman 10 January 1998
1273 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1275 /* Get rid of any futexes when releasing the mm */
1277 if (unlikely(tsk
->robust_list
)) {
1278 exit_robust_list(tsk
);
1279 tsk
->robust_list
= NULL
;
1281 #ifdef CONFIG_COMPAT
1282 if (unlikely(tsk
->compat_robust_list
)) {
1283 compat_exit_robust_list(tsk
);
1284 tsk
->compat_robust_list
= NULL
;
1287 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1288 exit_pi_state_list(tsk
);
1291 uprobe_free_utask(tsk
);
1293 /* Get rid of any cached register state */
1294 deactivate_mm(tsk
, mm
);
1297 * Signal userspace if we're not exiting with a core dump
1298 * because we want to leave the value intact for debugging
1301 if (tsk
->clear_child_tid
) {
1302 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1303 atomic_read(&mm
->mm_users
) > 1) {
1305 * We don't check the error code - if userspace has
1306 * not set up a proper pointer then tough luck.
1308 put_user(0, tsk
->clear_child_tid
);
1309 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1310 1, NULL
, NULL
, 0, 0);
1312 tsk
->clear_child_tid
= NULL
;
1316 * All done, finally we can wake up parent and return this mm to him.
1317 * Also kthread_stop() uses this completion for synchronization.
1319 if (tsk
->vfork_done
)
1320 complete_vfork_done(tsk
);
1324 * dup_mm() - duplicates an existing mm structure
1325 * @tsk: the task_struct with which the new mm will be associated.
1326 * @oldmm: the mm to duplicate.
1328 * Allocates a new mm structure and duplicates the provided @oldmm structure
1331 * Return: the duplicated mm or NULL on failure.
1333 static struct mm_struct
*dup_mm(struct task_struct
*tsk
,
1334 struct mm_struct
*oldmm
)
1336 struct mm_struct
*mm
;
1343 memcpy(mm
, oldmm
, sizeof(*mm
));
1345 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1348 err
= dup_mmap(mm
, oldmm
);
1352 mm
->hiwater_rss
= get_mm_rss(mm
);
1353 mm
->hiwater_vm
= mm
->total_vm
;
1355 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1361 /* don't put binfmt in mmput, we haven't got module yet */
1363 mm_init_owner(mm
, NULL
);
1370 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1372 struct mm_struct
*mm
, *oldmm
;
1375 tsk
->min_flt
= tsk
->maj_flt
= 0;
1376 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1377 #ifdef CONFIG_DETECT_HUNG_TASK
1378 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1379 tsk
->last_switch_time
= 0;
1383 tsk
->active_mm
= NULL
;
1386 * Are we cloning a kernel thread?
1388 * We need to steal a active VM for that..
1390 oldmm
= current
->mm
;
1394 /* initialize the new vmacache entries */
1395 vmacache_flush(tsk
);
1397 if (clone_flags
& CLONE_VM
) {
1404 mm
= dup_mm(tsk
, current
->mm
);
1410 tsk
->active_mm
= mm
;
1417 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1419 struct fs_struct
*fs
= current
->fs
;
1420 if (clone_flags
& CLONE_FS
) {
1421 /* tsk->fs is already what we want */
1422 spin_lock(&fs
->lock
);
1424 spin_unlock(&fs
->lock
);
1428 spin_unlock(&fs
->lock
);
1431 tsk
->fs
= copy_fs_struct(fs
);
1437 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1439 struct files_struct
*oldf
, *newf
;
1443 * A background process may not have any files ...
1445 oldf
= current
->files
;
1449 if (clone_flags
& CLONE_FILES
) {
1450 atomic_inc(&oldf
->count
);
1454 newf
= dup_fd(oldf
, &error
);
1464 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1467 struct io_context
*ioc
= current
->io_context
;
1468 struct io_context
*new_ioc
;
1473 * Share io context with parent, if CLONE_IO is set
1475 if (clone_flags
& CLONE_IO
) {
1477 tsk
->io_context
= ioc
;
1478 } else if (ioprio_valid(ioc
->ioprio
)) {
1479 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1480 if (unlikely(!new_ioc
))
1483 new_ioc
->ioprio
= ioc
->ioprio
;
1484 put_io_context(new_ioc
);
1490 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1492 struct sighand_struct
*sig
;
1494 if (clone_flags
& CLONE_SIGHAND
) {
1495 refcount_inc(¤t
->sighand
->count
);
1498 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1499 rcu_assign_pointer(tsk
->sighand
, sig
);
1503 refcount_set(&sig
->count
, 1);
1504 spin_lock_irq(¤t
->sighand
->siglock
);
1505 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1506 spin_unlock_irq(¤t
->sighand
->siglock
);
1510 void __cleanup_sighand(struct sighand_struct
*sighand
)
1512 if (refcount_dec_and_test(&sighand
->count
)) {
1513 signalfd_cleanup(sighand
);
1515 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1516 * without an RCU grace period, see __lock_task_sighand().
1518 kmem_cache_free(sighand_cachep
, sighand
);
1523 * Initialize POSIX timer handling for a thread group.
1525 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1527 struct posix_cputimers
*pct
= &sig
->posix_cputimers
;
1528 unsigned long cpu_limit
;
1530 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1531 posix_cputimers_group_init(pct
, cpu_limit
);
1534 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1536 struct signal_struct
*sig
;
1538 if (clone_flags
& CLONE_THREAD
)
1541 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1546 sig
->nr_threads
= 1;
1547 atomic_set(&sig
->live
, 1);
1548 refcount_set(&sig
->sigcnt
, 1);
1550 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1551 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1552 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1554 init_waitqueue_head(&sig
->wait_chldexit
);
1555 sig
->curr_target
= tsk
;
1556 init_sigpending(&sig
->shared_pending
);
1557 INIT_HLIST_HEAD(&sig
->multiprocess
);
1558 seqlock_init(&sig
->stats_lock
);
1559 prev_cputime_init(&sig
->prev_cputime
);
1561 #ifdef CONFIG_POSIX_TIMERS
1562 INIT_LIST_HEAD(&sig
->posix_timers
);
1563 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1564 sig
->real_timer
.function
= it_real_fn
;
1567 task_lock(current
->group_leader
);
1568 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1569 task_unlock(current
->group_leader
);
1571 posix_cpu_timers_init_group(sig
);
1573 tty_audit_fork(sig
);
1574 sched_autogroup_fork(sig
);
1576 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1577 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1579 mutex_init(&sig
->cred_guard_mutex
);
1584 static void copy_seccomp(struct task_struct
*p
)
1586 #ifdef CONFIG_SECCOMP
1588 * Must be called with sighand->lock held, which is common to
1589 * all threads in the group. Holding cred_guard_mutex is not
1590 * needed because this new task is not yet running and cannot
1593 assert_spin_locked(¤t
->sighand
->siglock
);
1595 /* Ref-count the new filter user, and assign it. */
1596 get_seccomp_filter(current
);
1597 p
->seccomp
= current
->seccomp
;
1600 * Explicitly enable no_new_privs here in case it got set
1601 * between the task_struct being duplicated and holding the
1602 * sighand lock. The seccomp state and nnp must be in sync.
1604 if (task_no_new_privs(current
))
1605 task_set_no_new_privs(p
);
1608 * If the parent gained a seccomp mode after copying thread
1609 * flags and between before we held the sighand lock, we have
1610 * to manually enable the seccomp thread flag here.
1612 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1613 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1617 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1619 current
->clear_child_tid
= tidptr
;
1621 return task_pid_vnr(current
);
1624 static void rt_mutex_init_task(struct task_struct
*p
)
1626 raw_spin_lock_init(&p
->pi_lock
);
1627 #ifdef CONFIG_RT_MUTEXES
1628 p
->pi_waiters
= RB_ROOT_CACHED
;
1629 p
->pi_top_task
= NULL
;
1630 p
->pi_blocked_on
= NULL
;
1634 static inline void init_task_pid_links(struct task_struct
*task
)
1638 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1639 INIT_HLIST_NODE(&task
->pid_links
[type
]);
1644 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1646 if (type
== PIDTYPE_PID
)
1647 task
->thread_pid
= pid
;
1649 task
->signal
->pids
[type
] = pid
;
1652 static inline void rcu_copy_process(struct task_struct
*p
)
1654 #ifdef CONFIG_PREEMPT_RCU
1655 p
->rcu_read_lock_nesting
= 0;
1656 p
->rcu_read_unlock_special
.s
= 0;
1657 p
->rcu_blocked_node
= NULL
;
1658 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1659 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1660 #ifdef CONFIG_TASKS_RCU
1661 p
->rcu_tasks_holdout
= false;
1662 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1663 p
->rcu_tasks_idle_cpu
= -1;
1664 #endif /* #ifdef CONFIG_TASKS_RCU */
1667 struct pid
*pidfd_pid(const struct file
*file
)
1669 if (file
->f_op
== &pidfd_fops
)
1670 return file
->private_data
;
1672 return ERR_PTR(-EBADF
);
1675 static int pidfd_release(struct inode
*inode
, struct file
*file
)
1677 struct pid
*pid
= file
->private_data
;
1679 file
->private_data
= NULL
;
1684 #ifdef CONFIG_PROC_FS
1685 static void pidfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
1687 struct pid_namespace
*ns
= proc_pid_ns(file_inode(m
->file
));
1688 struct pid
*pid
= f
->private_data
;
1690 seq_put_decimal_ull(m
, "Pid:\t", pid_nr_ns(pid
, ns
));
1696 * Poll support for process exit notification.
1698 static unsigned int pidfd_poll(struct file
*file
, struct poll_table_struct
*pts
)
1700 struct task_struct
*task
;
1701 struct pid
*pid
= file
->private_data
;
1704 poll_wait(file
, &pid
->wait_pidfd
, pts
);
1707 task
= pid_task(pid
, PIDTYPE_PID
);
1709 * Inform pollers only when the whole thread group exits.
1710 * If the thread group leader exits before all other threads in the
1711 * group, then poll(2) should block, similar to the wait(2) family.
1713 if (!task
|| (task
->exit_state
&& thread_group_empty(task
)))
1714 poll_flags
= POLLIN
| POLLRDNORM
;
1720 const struct file_operations pidfd_fops
= {
1721 .release
= pidfd_release
,
1723 #ifdef CONFIG_PROC_FS
1724 .show_fdinfo
= pidfd_show_fdinfo
,
1728 static void __delayed_free_task(struct rcu_head
*rhp
)
1730 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
1735 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
1737 if (IS_ENABLED(CONFIG_MEMCG
))
1738 call_rcu(&tsk
->rcu
, __delayed_free_task
);
1744 * This creates a new process as a copy of the old one,
1745 * but does not actually start it yet.
1747 * It copies the registers, and all the appropriate
1748 * parts of the process environment (as per the clone
1749 * flags). The actual kick-off is left to the caller.
1751 static __latent_entropy
struct task_struct
*copy_process(
1755 struct kernel_clone_args
*args
)
1757 int pidfd
= -1, retval
;
1758 struct task_struct
*p
;
1759 struct multiprocess_signals delayed
;
1760 struct file
*pidfile
= NULL
;
1761 u64 clone_flags
= args
->flags
;
1764 * Don't allow sharing the root directory with processes in a different
1767 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1768 return ERR_PTR(-EINVAL
);
1770 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1771 return ERR_PTR(-EINVAL
);
1774 * Thread groups must share signals as well, and detached threads
1775 * can only be started up within the thread group.
1777 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1778 return ERR_PTR(-EINVAL
);
1781 * Shared signal handlers imply shared VM. By way of the above,
1782 * thread groups also imply shared VM. Blocking this case allows
1783 * for various simplifications in other code.
1785 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1786 return ERR_PTR(-EINVAL
);
1789 * Siblings of global init remain as zombies on exit since they are
1790 * not reaped by their parent (swapper). To solve this and to avoid
1791 * multi-rooted process trees, prevent global and container-inits
1792 * from creating siblings.
1794 if ((clone_flags
& CLONE_PARENT
) &&
1795 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1796 return ERR_PTR(-EINVAL
);
1799 * If the new process will be in a different pid or user namespace
1800 * do not allow it to share a thread group with the forking task.
1802 if (clone_flags
& CLONE_THREAD
) {
1803 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1804 (task_active_pid_ns(current
) !=
1805 current
->nsproxy
->pid_ns_for_children
))
1806 return ERR_PTR(-EINVAL
);
1809 if (clone_flags
& CLONE_PIDFD
) {
1811 * - CLONE_DETACHED is blocked so that we can potentially
1812 * reuse it later for CLONE_PIDFD.
1813 * - CLONE_THREAD is blocked until someone really needs it.
1815 if (clone_flags
& (CLONE_DETACHED
| CLONE_THREAD
))
1816 return ERR_PTR(-EINVAL
);
1820 * Force any signals received before this point to be delivered
1821 * before the fork happens. Collect up signals sent to multiple
1822 * processes that happen during the fork and delay them so that
1823 * they appear to happen after the fork.
1825 sigemptyset(&delayed
.signal
);
1826 INIT_HLIST_NODE(&delayed
.node
);
1828 spin_lock_irq(¤t
->sighand
->siglock
);
1829 if (!(clone_flags
& CLONE_THREAD
))
1830 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
1831 recalc_sigpending();
1832 spin_unlock_irq(¤t
->sighand
->siglock
);
1833 retval
= -ERESTARTNOINTR
;
1834 if (signal_pending(current
))
1838 p
= dup_task_struct(current
, node
);
1843 * This _must_ happen before we call free_task(), i.e. before we jump
1844 * to any of the bad_fork_* labels. This is to avoid freeing
1845 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1846 * kernel threads (PF_KTHREAD).
1848 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? args
->child_tid
: NULL
;
1850 * Clear TID on mm_release()?
1852 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? args
->child_tid
: NULL
;
1854 ftrace_graph_init_task(p
);
1856 rt_mutex_init_task(p
);
1858 #ifdef CONFIG_PROVE_LOCKING
1859 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1860 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1863 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1864 task_rlimit(p
, RLIMIT_NPROC
)) {
1865 if (p
->real_cred
->user
!= INIT_USER
&&
1866 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1869 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1871 retval
= copy_creds(p
, clone_flags
);
1876 * If multiple threads are within copy_process(), then this check
1877 * triggers too late. This doesn't hurt, the check is only there
1878 * to stop root fork bombs.
1881 if (nr_threads
>= max_threads
)
1882 goto bad_fork_cleanup_count
;
1884 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1885 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1886 p
->flags
|= PF_FORKNOEXEC
;
1887 INIT_LIST_HEAD(&p
->children
);
1888 INIT_LIST_HEAD(&p
->sibling
);
1889 rcu_copy_process(p
);
1890 p
->vfork_done
= NULL
;
1891 spin_lock_init(&p
->alloc_lock
);
1893 init_sigpending(&p
->pending
);
1895 p
->utime
= p
->stime
= p
->gtime
= 0;
1896 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1897 p
->utimescaled
= p
->stimescaled
= 0;
1899 prev_cputime_init(&p
->prev_cputime
);
1901 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1902 seqcount_init(&p
->vtime
.seqcount
);
1903 p
->vtime
.starttime
= 0;
1904 p
->vtime
.state
= VTIME_INACTIVE
;
1907 #if defined(SPLIT_RSS_COUNTING)
1908 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1911 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1917 task_io_accounting_init(&p
->ioac
);
1918 acct_clear_integrals(p
);
1920 posix_cputimers_init(&p
->posix_cputimers
);
1922 p
->io_context
= NULL
;
1923 audit_set_context(p
, NULL
);
1926 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1927 if (IS_ERR(p
->mempolicy
)) {
1928 retval
= PTR_ERR(p
->mempolicy
);
1929 p
->mempolicy
= NULL
;
1930 goto bad_fork_cleanup_threadgroup_lock
;
1933 #ifdef CONFIG_CPUSETS
1934 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1935 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1936 seqcount_init(&p
->mems_allowed_seq
);
1938 #ifdef CONFIG_TRACE_IRQFLAGS
1940 p
->hardirqs_enabled
= 0;
1941 p
->hardirq_enable_ip
= 0;
1942 p
->hardirq_enable_event
= 0;
1943 p
->hardirq_disable_ip
= _THIS_IP_
;
1944 p
->hardirq_disable_event
= 0;
1945 p
->softirqs_enabled
= 1;
1946 p
->softirq_enable_ip
= _THIS_IP_
;
1947 p
->softirq_enable_event
= 0;
1948 p
->softirq_disable_ip
= 0;
1949 p
->softirq_disable_event
= 0;
1950 p
->hardirq_context
= 0;
1951 p
->softirq_context
= 0;
1954 p
->pagefault_disabled
= 0;
1956 #ifdef CONFIG_LOCKDEP
1957 lockdep_init_task(p
);
1960 #ifdef CONFIG_DEBUG_MUTEXES
1961 p
->blocked_on
= NULL
; /* not blocked yet */
1963 #ifdef CONFIG_BCACHE
1964 p
->sequential_io
= 0;
1965 p
->sequential_io_avg
= 0;
1968 /* Perform scheduler related setup. Assign this task to a CPU. */
1969 retval
= sched_fork(clone_flags
, p
);
1971 goto bad_fork_cleanup_policy
;
1973 retval
= perf_event_init_task(p
);
1975 goto bad_fork_cleanup_policy
;
1976 retval
= audit_alloc(p
);
1978 goto bad_fork_cleanup_perf
;
1979 /* copy all the process information */
1981 retval
= security_task_alloc(p
, clone_flags
);
1983 goto bad_fork_cleanup_audit
;
1984 retval
= copy_semundo(clone_flags
, p
);
1986 goto bad_fork_cleanup_security
;
1987 retval
= copy_files(clone_flags
, p
);
1989 goto bad_fork_cleanup_semundo
;
1990 retval
= copy_fs(clone_flags
, p
);
1992 goto bad_fork_cleanup_files
;
1993 retval
= copy_sighand(clone_flags
, p
);
1995 goto bad_fork_cleanup_fs
;
1996 retval
= copy_signal(clone_flags
, p
);
1998 goto bad_fork_cleanup_sighand
;
1999 retval
= copy_mm(clone_flags
, p
);
2001 goto bad_fork_cleanup_signal
;
2002 retval
= copy_namespaces(clone_flags
, p
);
2004 goto bad_fork_cleanup_mm
;
2005 retval
= copy_io(clone_flags
, p
);
2007 goto bad_fork_cleanup_namespaces
;
2008 retval
= copy_thread_tls(clone_flags
, args
->stack
, args
->stack_size
, p
,
2011 goto bad_fork_cleanup_io
;
2013 stackleak_task_init(p
);
2015 if (pid
!= &init_struct_pid
) {
2016 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
2018 retval
= PTR_ERR(pid
);
2019 goto bad_fork_cleanup_thread
;
2024 * This has to happen after we've potentially unshared the file
2025 * descriptor table (so that the pidfd doesn't leak into the child
2026 * if the fd table isn't shared).
2028 if (clone_flags
& CLONE_PIDFD
) {
2029 retval
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2031 goto bad_fork_free_pid
;
2035 pidfile
= anon_inode_getfile("[pidfd]", &pidfd_fops
, pid
,
2036 O_RDWR
| O_CLOEXEC
);
2037 if (IS_ERR(pidfile
)) {
2038 put_unused_fd(pidfd
);
2039 retval
= PTR_ERR(pidfile
);
2040 goto bad_fork_free_pid
;
2042 get_pid(pid
); /* held by pidfile now */
2044 retval
= put_user(pidfd
, args
->pidfd
);
2046 goto bad_fork_put_pidfd
;
2053 p
->robust_list
= NULL
;
2054 #ifdef CONFIG_COMPAT
2055 p
->compat_robust_list
= NULL
;
2057 INIT_LIST_HEAD(&p
->pi_state_list
);
2058 p
->pi_state_cache
= NULL
;
2061 * sigaltstack should be cleared when sharing the same VM
2063 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
2067 * Syscall tracing and stepping should be turned off in the
2068 * child regardless of CLONE_PTRACE.
2070 user_disable_single_step(p
);
2071 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
2072 #ifdef TIF_SYSCALL_EMU
2073 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
2075 clear_tsk_latency_tracing(p
);
2077 /* ok, now we should be set up.. */
2078 p
->pid
= pid_nr(pid
);
2079 if (clone_flags
& CLONE_THREAD
) {
2080 p
->exit_signal
= -1;
2081 p
->group_leader
= current
->group_leader
;
2082 p
->tgid
= current
->tgid
;
2084 if (clone_flags
& CLONE_PARENT
)
2085 p
->exit_signal
= current
->group_leader
->exit_signal
;
2087 p
->exit_signal
= args
->exit_signal
;
2088 p
->group_leader
= p
;
2093 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2094 p
->dirty_paused_when
= 0;
2096 p
->pdeath_signal
= 0;
2097 INIT_LIST_HEAD(&p
->thread_group
);
2098 p
->task_works
= NULL
;
2100 cgroup_threadgroup_change_begin(current
);
2102 * Ensure that the cgroup subsystem policies allow the new process to be
2103 * forked. It should be noted the the new process's css_set can be changed
2104 * between here and cgroup_post_fork() if an organisation operation is in
2107 retval
= cgroup_can_fork(p
);
2109 goto bad_fork_cgroup_threadgroup_change_end
;
2112 * From this point on we must avoid any synchronous user-space
2113 * communication until we take the tasklist-lock. In particular, we do
2114 * not want user-space to be able to predict the process start-time by
2115 * stalling fork(2) after we recorded the start_time but before it is
2116 * visible to the system.
2119 p
->start_time
= ktime_get_ns();
2120 p
->real_start_time
= ktime_get_boottime_ns();
2123 * Make it visible to the rest of the system, but dont wake it up yet.
2124 * Need tasklist lock for parent etc handling!
2126 write_lock_irq(&tasklist_lock
);
2128 /* CLONE_PARENT re-uses the old parent */
2129 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2130 p
->real_parent
= current
->real_parent
;
2131 p
->parent_exec_id
= current
->parent_exec_id
;
2133 p
->real_parent
= current
;
2134 p
->parent_exec_id
= current
->self_exec_id
;
2137 klp_copy_process(p
);
2139 spin_lock(¤t
->sighand
->siglock
);
2142 * Copy seccomp details explicitly here, in case they were changed
2143 * before holding sighand lock.
2147 rseq_fork(p
, clone_flags
);
2149 /* Don't start children in a dying pid namespace */
2150 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2152 goto bad_fork_cancel_cgroup
;
2155 /* Let kill terminate clone/fork in the middle */
2156 if (fatal_signal_pending(current
)) {
2158 goto bad_fork_cancel_cgroup
;
2161 /* past the last point of failure */
2163 fd_install(pidfd
, pidfile
);
2165 init_task_pid_links(p
);
2166 if (likely(p
->pid
)) {
2167 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2169 init_task_pid(p
, PIDTYPE_PID
, pid
);
2170 if (thread_group_leader(p
)) {
2171 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2172 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2173 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2175 if (is_child_reaper(pid
)) {
2176 ns_of_pid(pid
)->child_reaper
= p
;
2177 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2179 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2180 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2182 * Inherit has_child_subreaper flag under the same
2183 * tasklist_lock with adding child to the process tree
2184 * for propagate_has_child_subreaper optimization.
2186 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2187 p
->real_parent
->signal
->is_child_subreaper
;
2188 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2189 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2190 attach_pid(p
, PIDTYPE_TGID
);
2191 attach_pid(p
, PIDTYPE_PGID
);
2192 attach_pid(p
, PIDTYPE_SID
);
2193 __this_cpu_inc(process_counts
);
2195 current
->signal
->nr_threads
++;
2196 atomic_inc(¤t
->signal
->live
);
2197 refcount_inc(¤t
->signal
->sigcnt
);
2198 task_join_group_stop(p
);
2199 list_add_tail_rcu(&p
->thread_group
,
2200 &p
->group_leader
->thread_group
);
2201 list_add_tail_rcu(&p
->thread_node
,
2202 &p
->signal
->thread_head
);
2204 attach_pid(p
, PIDTYPE_PID
);
2208 hlist_del_init(&delayed
.node
);
2209 spin_unlock(¤t
->sighand
->siglock
);
2210 syscall_tracepoint_update(p
);
2211 write_unlock_irq(&tasklist_lock
);
2213 proc_fork_connector(p
);
2214 cgroup_post_fork(p
);
2215 cgroup_threadgroup_change_end(current
);
2218 trace_task_newtask(p
, clone_flags
);
2219 uprobe_copy_process(p
, clone_flags
);
2223 bad_fork_cancel_cgroup
:
2224 spin_unlock(¤t
->sighand
->siglock
);
2225 write_unlock_irq(&tasklist_lock
);
2226 cgroup_cancel_fork(p
);
2227 bad_fork_cgroup_threadgroup_change_end
:
2228 cgroup_threadgroup_change_end(current
);
2230 if (clone_flags
& CLONE_PIDFD
) {
2232 put_unused_fd(pidfd
);
2235 if (pid
!= &init_struct_pid
)
2237 bad_fork_cleanup_thread
:
2239 bad_fork_cleanup_io
:
2242 bad_fork_cleanup_namespaces
:
2243 exit_task_namespaces(p
);
2244 bad_fork_cleanup_mm
:
2246 mm_clear_owner(p
->mm
, p
);
2249 bad_fork_cleanup_signal
:
2250 if (!(clone_flags
& CLONE_THREAD
))
2251 free_signal_struct(p
->signal
);
2252 bad_fork_cleanup_sighand
:
2253 __cleanup_sighand(p
->sighand
);
2254 bad_fork_cleanup_fs
:
2255 exit_fs(p
); /* blocking */
2256 bad_fork_cleanup_files
:
2257 exit_files(p
); /* blocking */
2258 bad_fork_cleanup_semundo
:
2260 bad_fork_cleanup_security
:
2261 security_task_free(p
);
2262 bad_fork_cleanup_audit
:
2264 bad_fork_cleanup_perf
:
2265 perf_event_free_task(p
);
2266 bad_fork_cleanup_policy
:
2267 lockdep_free_task(p
);
2269 mpol_put(p
->mempolicy
);
2270 bad_fork_cleanup_threadgroup_lock
:
2272 delayacct_tsk_free(p
);
2273 bad_fork_cleanup_count
:
2274 atomic_dec(&p
->cred
->user
->processes
);
2277 p
->state
= TASK_DEAD
;
2279 delayed_free_task(p
);
2281 spin_lock_irq(¤t
->sighand
->siglock
);
2282 hlist_del_init(&delayed
.node
);
2283 spin_unlock_irq(¤t
->sighand
->siglock
);
2284 return ERR_PTR(retval
);
2287 static inline void init_idle_pids(struct task_struct
*idle
)
2291 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2292 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2293 init_task_pid(idle
, type
, &init_struct_pid
);
2297 struct task_struct
*fork_idle(int cpu
)
2299 struct task_struct
*task
;
2300 struct kernel_clone_args args
= {
2304 task
= copy_process(&init_struct_pid
, 0, cpu_to_node(cpu
), &args
);
2305 if (!IS_ERR(task
)) {
2306 init_idle_pids(task
);
2307 init_idle(task
, cpu
);
2313 struct mm_struct
*copy_init_mm(void)
2315 return dup_mm(NULL
, &init_mm
);
2319 * Ok, this is the main fork-routine.
2321 * It copies the process, and if successful kick-starts
2322 * it and waits for it to finish using the VM if required.
2324 * args->exit_signal is expected to be checked for sanity by the caller.
2326 long _do_fork(struct kernel_clone_args
*args
)
2328 u64 clone_flags
= args
->flags
;
2329 struct completion vfork
;
2331 struct task_struct
*p
;
2336 * Determine whether and which event to report to ptracer. When
2337 * called from kernel_thread or CLONE_UNTRACED is explicitly
2338 * requested, no event is reported; otherwise, report if the event
2339 * for the type of forking is enabled.
2341 if (!(clone_flags
& CLONE_UNTRACED
)) {
2342 if (clone_flags
& CLONE_VFORK
)
2343 trace
= PTRACE_EVENT_VFORK
;
2344 else if (args
->exit_signal
!= SIGCHLD
)
2345 trace
= PTRACE_EVENT_CLONE
;
2347 trace
= PTRACE_EVENT_FORK
;
2349 if (likely(!ptrace_event_enabled(current
, trace
)))
2353 p
= copy_process(NULL
, trace
, NUMA_NO_NODE
, args
);
2354 add_latent_entropy();
2360 * Do this prior waking up the new thread - the thread pointer
2361 * might get invalid after that point, if the thread exits quickly.
2363 trace_sched_process_fork(current
, p
);
2365 pid
= get_task_pid(p
, PIDTYPE_PID
);
2368 if (clone_flags
& CLONE_PARENT_SETTID
)
2369 put_user(nr
, args
->parent_tid
);
2371 if (clone_flags
& CLONE_VFORK
) {
2372 p
->vfork_done
= &vfork
;
2373 init_completion(&vfork
);
2377 wake_up_new_task(p
);
2379 /* forking complete and child started to run, tell ptracer */
2380 if (unlikely(trace
))
2381 ptrace_event_pid(trace
, pid
);
2383 if (clone_flags
& CLONE_VFORK
) {
2384 if (!wait_for_vfork_done(p
, &vfork
))
2385 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2392 bool legacy_clone_args_valid(const struct kernel_clone_args
*kargs
)
2394 /* clone(CLONE_PIDFD) uses parent_tidptr to return a pidfd */
2395 if ((kargs
->flags
& CLONE_PIDFD
) &&
2396 (kargs
->flags
& CLONE_PARENT_SETTID
))
2402 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2403 /* For compatibility with architectures that call do_fork directly rather than
2404 * using the syscall entry points below. */
2405 long do_fork(unsigned long clone_flags
,
2406 unsigned long stack_start
,
2407 unsigned long stack_size
,
2408 int __user
*parent_tidptr
,
2409 int __user
*child_tidptr
)
2411 struct kernel_clone_args args
= {
2412 .flags
= (clone_flags
& ~CSIGNAL
),
2413 .pidfd
= parent_tidptr
,
2414 .child_tid
= child_tidptr
,
2415 .parent_tid
= parent_tidptr
,
2416 .exit_signal
= (clone_flags
& CSIGNAL
),
2417 .stack
= stack_start
,
2418 .stack_size
= stack_size
,
2421 if (!legacy_clone_args_valid(&args
))
2424 return _do_fork(&args
);
2429 * Create a kernel thread.
2431 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2433 struct kernel_clone_args args
= {
2434 .flags
= ((flags
| CLONE_VM
| CLONE_UNTRACED
) & ~CSIGNAL
),
2435 .exit_signal
= (flags
& CSIGNAL
),
2436 .stack
= (unsigned long)fn
,
2437 .stack_size
= (unsigned long)arg
,
2440 return _do_fork(&args
);
2443 #ifdef __ARCH_WANT_SYS_FORK
2444 SYSCALL_DEFINE0(fork
)
2447 struct kernel_clone_args args
= {
2448 .exit_signal
= SIGCHLD
,
2451 return _do_fork(&args
);
2453 /* can not support in nommu mode */
2459 #ifdef __ARCH_WANT_SYS_VFORK
2460 SYSCALL_DEFINE0(vfork
)
2462 struct kernel_clone_args args
= {
2463 .flags
= CLONE_VFORK
| CLONE_VM
,
2464 .exit_signal
= SIGCHLD
,
2467 return _do_fork(&args
);
2471 #ifdef __ARCH_WANT_SYS_CLONE
2472 #ifdef CONFIG_CLONE_BACKWARDS
2473 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2474 int __user
*, parent_tidptr
,
2476 int __user
*, child_tidptr
)
2477 #elif defined(CONFIG_CLONE_BACKWARDS2)
2478 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2479 int __user
*, parent_tidptr
,
2480 int __user
*, child_tidptr
,
2482 #elif defined(CONFIG_CLONE_BACKWARDS3)
2483 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2485 int __user
*, parent_tidptr
,
2486 int __user
*, child_tidptr
,
2489 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2490 int __user
*, parent_tidptr
,
2491 int __user
*, child_tidptr
,
2495 struct kernel_clone_args args
= {
2496 .flags
= (clone_flags
& ~CSIGNAL
),
2497 .pidfd
= parent_tidptr
,
2498 .child_tid
= child_tidptr
,
2499 .parent_tid
= parent_tidptr
,
2500 .exit_signal
= (clone_flags
& CSIGNAL
),
2505 if (!legacy_clone_args_valid(&args
))
2508 return _do_fork(&args
);
2512 #ifdef __ARCH_WANT_SYS_CLONE3
2513 noinline
static int copy_clone_args_from_user(struct kernel_clone_args
*kargs
,
2514 struct clone_args __user
*uargs
,
2517 struct clone_args args
;
2519 if (unlikely(size
> PAGE_SIZE
))
2522 if (unlikely(size
< sizeof(struct clone_args
)))
2525 if (unlikely(!access_ok(uargs
, size
)))
2528 if (size
> sizeof(struct clone_args
)) {
2529 unsigned char __user
*addr
;
2530 unsigned char __user
*end
;
2533 addr
= (void __user
*)uargs
+ sizeof(struct clone_args
);
2534 end
= (void __user
*)uargs
+ size
;
2536 for (; addr
< end
; addr
++) {
2537 if (get_user(val
, addr
))
2543 size
= sizeof(struct clone_args
);
2546 if (copy_from_user(&args
, uargs
, size
))
2550 * Verify that higher 32bits of exit_signal are unset and that
2551 * it is a valid signal
2553 if (unlikely((args
.exit_signal
& ~((u64
)CSIGNAL
)) ||
2554 !valid_signal(args
.exit_signal
)))
2557 *kargs
= (struct kernel_clone_args
){
2558 .flags
= args
.flags
,
2559 .pidfd
= u64_to_user_ptr(args
.pidfd
),
2560 .child_tid
= u64_to_user_ptr(args
.child_tid
),
2561 .parent_tid
= u64_to_user_ptr(args
.parent_tid
),
2562 .exit_signal
= args
.exit_signal
,
2563 .stack
= args
.stack
,
2564 .stack_size
= args
.stack_size
,
2571 static bool clone3_args_valid(const struct kernel_clone_args
*kargs
)
2574 * All lower bits of the flag word are taken.
2575 * Verify that no other unknown flags are passed along.
2577 if (kargs
->flags
& ~CLONE_LEGACY_FLAGS
)
2581 * - make the CLONE_DETACHED bit reuseable for clone3
2582 * - make the CSIGNAL bits reuseable for clone3
2584 if (kargs
->flags
& (CLONE_DETACHED
| CSIGNAL
))
2587 if ((kargs
->flags
& (CLONE_THREAD
| CLONE_PARENT
)) &&
2594 SYSCALL_DEFINE2(clone3
, struct clone_args __user
*, uargs
, size_t, size
)
2598 struct kernel_clone_args kargs
;
2600 err
= copy_clone_args_from_user(&kargs
, uargs
, size
);
2604 if (!clone3_args_valid(&kargs
))
2607 return _do_fork(&kargs
);
2611 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2613 struct task_struct
*leader
, *parent
, *child
;
2616 read_lock(&tasklist_lock
);
2617 leader
= top
= top
->group_leader
;
2619 for_each_thread(leader
, parent
) {
2620 list_for_each_entry(child
, &parent
->children
, sibling
) {
2621 res
= visitor(child
, data
);
2633 if (leader
!= top
) {
2635 parent
= child
->real_parent
;
2636 leader
= parent
->group_leader
;
2640 read_unlock(&tasklist_lock
);
2643 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2644 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2647 static void sighand_ctor(void *data
)
2649 struct sighand_struct
*sighand
= data
;
2651 spin_lock_init(&sighand
->siglock
);
2652 init_waitqueue_head(&sighand
->signalfd_wqh
);
2655 void __init
proc_caches_init(void)
2657 unsigned int mm_size
;
2659 sighand_cachep
= kmem_cache_create("sighand_cache",
2660 sizeof(struct sighand_struct
), 0,
2661 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
2662 SLAB_ACCOUNT
, sighand_ctor
);
2663 signal_cachep
= kmem_cache_create("signal_cache",
2664 sizeof(struct signal_struct
), 0,
2665 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2667 files_cachep
= kmem_cache_create("files_cache",
2668 sizeof(struct files_struct
), 0,
2669 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2671 fs_cachep
= kmem_cache_create("fs_cache",
2672 sizeof(struct fs_struct
), 0,
2673 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2677 * The mm_cpumask is located at the end of mm_struct, and is
2678 * dynamically sized based on the maximum CPU number this system
2679 * can have, taking hotplug into account (nr_cpu_ids).
2681 mm_size
= sizeof(struct mm_struct
) + cpumask_size();
2683 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
2684 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
2685 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2686 offsetof(struct mm_struct
, saved_auxv
),
2687 sizeof_field(struct mm_struct
, saved_auxv
),
2689 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2691 nsproxy_cache_init();
2695 * Check constraints on flags passed to the unshare system call.
2697 static int check_unshare_flags(unsigned long unshare_flags
)
2699 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2700 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2701 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2702 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
))
2705 * Not implemented, but pretend it works if there is nothing
2706 * to unshare. Note that unsharing the address space or the
2707 * signal handlers also need to unshare the signal queues (aka
2710 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2711 if (!thread_group_empty(current
))
2714 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2715 if (refcount_read(¤t
->sighand
->count
) > 1)
2718 if (unshare_flags
& CLONE_VM
) {
2719 if (!current_is_single_threaded())
2727 * Unshare the filesystem structure if it is being shared
2729 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2731 struct fs_struct
*fs
= current
->fs
;
2733 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2736 /* don't need lock here; in the worst case we'll do useless copy */
2740 *new_fsp
= copy_fs_struct(fs
);
2748 * Unshare file descriptor table if it is being shared
2750 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2752 struct files_struct
*fd
= current
->files
;
2755 if ((unshare_flags
& CLONE_FILES
) &&
2756 (fd
&& atomic_read(&fd
->count
) > 1)) {
2757 *new_fdp
= dup_fd(fd
, &error
);
2766 * unshare allows a process to 'unshare' part of the process
2767 * context which was originally shared using clone. copy_*
2768 * functions used by do_fork() cannot be used here directly
2769 * because they modify an inactive task_struct that is being
2770 * constructed. Here we are modifying the current, active,
2773 int ksys_unshare(unsigned long unshare_flags
)
2775 struct fs_struct
*fs
, *new_fs
= NULL
;
2776 struct files_struct
*fd
, *new_fd
= NULL
;
2777 struct cred
*new_cred
= NULL
;
2778 struct nsproxy
*new_nsproxy
= NULL
;
2783 * If unsharing a user namespace must also unshare the thread group
2784 * and unshare the filesystem root and working directories.
2786 if (unshare_flags
& CLONE_NEWUSER
)
2787 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2789 * If unsharing vm, must also unshare signal handlers.
2791 if (unshare_flags
& CLONE_VM
)
2792 unshare_flags
|= CLONE_SIGHAND
;
2794 * If unsharing a signal handlers, must also unshare the signal queues.
2796 if (unshare_flags
& CLONE_SIGHAND
)
2797 unshare_flags
|= CLONE_THREAD
;
2799 * If unsharing namespace, must also unshare filesystem information.
2801 if (unshare_flags
& CLONE_NEWNS
)
2802 unshare_flags
|= CLONE_FS
;
2804 err
= check_unshare_flags(unshare_flags
);
2806 goto bad_unshare_out
;
2808 * CLONE_NEWIPC must also detach from the undolist: after switching
2809 * to a new ipc namespace, the semaphore arrays from the old
2810 * namespace are unreachable.
2812 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2814 err
= unshare_fs(unshare_flags
, &new_fs
);
2816 goto bad_unshare_out
;
2817 err
= unshare_fd(unshare_flags
, &new_fd
);
2819 goto bad_unshare_cleanup_fs
;
2820 err
= unshare_userns(unshare_flags
, &new_cred
);
2822 goto bad_unshare_cleanup_fd
;
2823 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2826 goto bad_unshare_cleanup_cred
;
2828 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2831 * CLONE_SYSVSEM is equivalent to sys_exit().
2835 if (unshare_flags
& CLONE_NEWIPC
) {
2836 /* Orphan segments in old ns (see sem above). */
2838 shm_init_task(current
);
2842 switch_task_namespaces(current
, new_nsproxy
);
2848 spin_lock(&fs
->lock
);
2849 current
->fs
= new_fs
;
2854 spin_unlock(&fs
->lock
);
2858 fd
= current
->files
;
2859 current
->files
= new_fd
;
2863 task_unlock(current
);
2866 /* Install the new user namespace */
2867 commit_creds(new_cred
);
2872 perf_event_namespaces(current
);
2874 bad_unshare_cleanup_cred
:
2877 bad_unshare_cleanup_fd
:
2879 put_files_struct(new_fd
);
2881 bad_unshare_cleanup_fs
:
2883 free_fs_struct(new_fs
);
2889 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
2891 return ksys_unshare(unshare_flags
);
2895 * Helper to unshare the files of the current task.
2896 * We don't want to expose copy_files internals to
2897 * the exec layer of the kernel.
2900 int unshare_files(struct files_struct
**displaced
)
2902 struct task_struct
*task
= current
;
2903 struct files_struct
*copy
= NULL
;
2906 error
= unshare_fd(CLONE_FILES
, ©
);
2907 if (error
|| !copy
) {
2911 *displaced
= task
->files
;
2918 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2919 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2923 int threads
= max_threads
;
2924 int min
= MIN_THREADS
;
2925 int max
= MAX_THREADS
;
2932 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2936 set_max_threads(threads
);