1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 * 'fork.c' contains the help-routines for the 'fork' system call
10 * (see also entry.S and others).
11 * Fork is rather simple, once you get the hang of it, but the memory
12 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
15 #include <linux/anon_inodes.h>
16 #include <linux/slab.h>
17 #include <linux/sched/autogroup.h>
18 #include <linux/sched/mm.h>
19 #include <linux/sched/coredump.h>
20 #include <linux/sched/user.h>
21 #include <linux/sched/numa_balancing.h>
22 #include <linux/sched/stat.h>
23 #include <linux/sched/task.h>
24 #include <linux/sched/task_stack.h>
25 #include <linux/sched/cputime.h>
26 #include <linux/seq_file.h>
27 #include <linux/rtmutex.h>
28 #include <linux/init.h>
29 #include <linux/unistd.h>
30 #include <linux/module.h>
31 #include <linux/vmalloc.h>
32 #include <linux/completion.h>
33 #include <linux/personality.h>
34 #include <linux/mempolicy.h>
35 #include <linux/sem.h>
36 #include <linux/file.h>
37 #include <linux/fdtable.h>
38 #include <linux/iocontext.h>
39 #include <linux/key.h>
40 #include <linux/kmsan.h>
41 #include <linux/binfmts.h>
42 #include <linux/mman.h>
43 #include <linux/mmu_notifier.h>
46 #include <linux/mm_inline.h>
47 #include <linux/nsproxy.h>
48 #include <linux/capability.h>
49 #include <linux/cpu.h>
50 #include <linux/cgroup.h>
51 #include <linux/security.h>
52 #include <linux/hugetlb.h>
53 #include <linux/seccomp.h>
54 #include <linux/swap.h>
55 #include <linux/syscalls.h>
56 #include <linux/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/tty.h>
79 #include <linux/fs_struct.h>
80 #include <linux/magic.h>
81 #include <linux/perf_event.h>
82 #include <linux/posix-timers.h>
83 #include <linux/user-return-notifier.h>
84 #include <linux/oom.h>
85 #include <linux/khugepaged.h>
86 #include <linux/signalfd.h>
87 #include <linux/uprobes.h>
88 #include <linux/aio.h>
89 #include <linux/compiler.h>
90 #include <linux/sysctl.h>
91 #include <linux/kcov.h>
92 #include <linux/livepatch.h>
93 #include <linux/thread_info.h>
94 #include <linux/stackleak.h>
95 #include <linux/kasan.h>
96 #include <linux/scs.h>
97 #include <linux/io_uring.h>
98 #include <linux/bpf.h>
99 #include <linux/stackprotector.h>
100 #include <linux/user_events.h>
101 #include <linux/iommu.h>
103 #include <asm/pgalloc.h>
104 #include <linux/uaccess.h>
105 #include <asm/mmu_context.h>
106 #include <asm/cacheflush.h>
107 #include <asm/tlbflush.h>
109 #include <trace/events/sched.h>
111 #define CREATE_TRACE_POINTS
112 #include <trace/events/task.h>
115 * Minimum number of threads to boot the kernel
117 #define MIN_THREADS 20
120 * Maximum number of threads
122 #define MAX_THREADS FUTEX_TID_MASK
125 * Protected counters by write_lock_irq(&tasklist_lock)
127 unsigned long total_forks
; /* Handle normal Linux uptimes. */
128 int nr_threads
; /* The idle threads do not count.. */
130 static int max_threads
; /* tunable limit on nr_threads */
132 #define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
134 static const char * const resident_page_types
[] = {
135 NAMED_ARRAY_INDEX(MM_FILEPAGES
),
136 NAMED_ARRAY_INDEX(MM_ANONPAGES
),
137 NAMED_ARRAY_INDEX(MM_SWAPENTS
),
138 NAMED_ARRAY_INDEX(MM_SHMEMPAGES
),
141 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
143 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
145 #ifdef CONFIG_PROVE_RCU
146 int lockdep_tasklist_lock_is_held(void)
148 return lockdep_is_held(&tasklist_lock
);
150 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
151 #endif /* #ifdef CONFIG_PROVE_RCU */
153 int nr_processes(void)
158 for_each_possible_cpu(cpu
)
159 total
+= per_cpu(process_counts
, cpu
);
164 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
168 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
169 static struct kmem_cache
*task_struct_cachep
;
171 static inline struct task_struct
*alloc_task_struct_node(int node
)
173 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
176 static inline void free_task_struct(struct task_struct
*tsk
)
178 kmem_cache_free(task_struct_cachep
, tsk
);
182 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
185 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
186 * kmemcache based allocator.
188 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
190 # ifdef CONFIG_VMAP_STACK
192 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
193 * flush. Try to minimize the number of calls by caching stacks.
195 #define NR_CACHED_STACKS 2
196 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
200 struct vm_struct
*stack_vm_area
;
203 static bool try_release_thread_stack_to_cache(struct vm_struct
*vm
)
207 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
208 if (this_cpu_cmpxchg(cached_stacks
[i
], NULL
, vm
) != NULL
)
215 static void thread_stack_free_rcu(struct rcu_head
*rh
)
217 struct vm_stack
*vm_stack
= container_of(rh
, struct vm_stack
, rcu
);
219 if (try_release_thread_stack_to_cache(vm_stack
->stack_vm_area
))
225 static void thread_stack_delayed_free(struct task_struct
*tsk
)
227 struct vm_stack
*vm_stack
= tsk
->stack
;
229 vm_stack
->stack_vm_area
= tsk
->stack_vm_area
;
230 call_rcu(&vm_stack
->rcu
, thread_stack_free_rcu
);
233 static int free_vm_stack_cache(unsigned int cpu
)
235 struct vm_struct
**cached_vm_stacks
= per_cpu_ptr(cached_stacks
, cpu
);
238 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
239 struct vm_struct
*vm_stack
= cached_vm_stacks
[i
];
244 vfree(vm_stack
->addr
);
245 cached_vm_stacks
[i
] = NULL
;
251 static int memcg_charge_kernel_stack(struct vm_struct
*vm
)
257 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
259 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
260 ret
= memcg_kmem_charge_page(vm
->pages
[i
], GFP_KERNEL
, 0);
267 for (i
= 0; i
< nr_charged
; i
++)
268 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
272 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
274 struct vm_struct
*vm
;
278 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
281 s
= this_cpu_xchg(cached_stacks
[i
], NULL
);
286 /* Reset stack metadata. */
287 kasan_unpoison_range(s
->addr
, THREAD_SIZE
);
289 stack
= kasan_reset_tag(s
->addr
);
291 /* Clear stale pointers from reused stack. */
292 memset(stack
, 0, THREAD_SIZE
);
294 if (memcg_charge_kernel_stack(s
)) {
299 tsk
->stack_vm_area
= s
;
305 * Allocated stacks are cached and later reused by new threads,
306 * so memcg accounting is performed manually on assigning/releasing
307 * stacks to tasks. Drop __GFP_ACCOUNT.
309 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_ALIGN
,
310 VMALLOC_START
, VMALLOC_END
,
311 THREADINFO_GFP
& ~__GFP_ACCOUNT
,
313 0, node
, __builtin_return_address(0));
317 vm
= find_vm_area(stack
);
318 if (memcg_charge_kernel_stack(vm
)) {
323 * We can't call find_vm_area() in interrupt context, and
324 * free_thread_stack() can be called in interrupt context,
325 * so cache the vm_struct.
327 tsk
->stack_vm_area
= vm
;
328 stack
= kasan_reset_tag(stack
);
333 static void free_thread_stack(struct task_struct
*tsk
)
335 if (!try_release_thread_stack_to_cache(tsk
->stack_vm_area
))
336 thread_stack_delayed_free(tsk
);
339 tsk
->stack_vm_area
= NULL
;
342 # else /* !CONFIG_VMAP_STACK */
344 static void thread_stack_free_rcu(struct rcu_head
*rh
)
346 __free_pages(virt_to_page(rh
), THREAD_SIZE_ORDER
);
349 static void thread_stack_delayed_free(struct task_struct
*tsk
)
351 struct rcu_head
*rh
= tsk
->stack
;
353 call_rcu(rh
, thread_stack_free_rcu
);
356 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
358 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
362 tsk
->stack
= kasan_reset_tag(page_address(page
));
368 static void free_thread_stack(struct task_struct
*tsk
)
370 thread_stack_delayed_free(tsk
);
374 # endif /* CONFIG_VMAP_STACK */
375 # else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
377 static struct kmem_cache
*thread_stack_cache
;
379 static void thread_stack_free_rcu(struct rcu_head
*rh
)
381 kmem_cache_free(thread_stack_cache
, rh
);
384 static void thread_stack_delayed_free(struct task_struct
*tsk
)
386 struct rcu_head
*rh
= tsk
->stack
;
388 call_rcu(rh
, thread_stack_free_rcu
);
391 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
393 unsigned long *stack
;
394 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
395 stack
= kasan_reset_tag(stack
);
397 return stack
? 0 : -ENOMEM
;
400 static void free_thread_stack(struct task_struct
*tsk
)
402 thread_stack_delayed_free(tsk
);
406 void thread_stack_cache_init(void)
408 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
409 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
411 BUG_ON(thread_stack_cache
== NULL
);
414 # endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
415 #else /* CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
417 static int alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
419 unsigned long *stack
;
421 stack
= arch_alloc_thread_stack_node(tsk
, node
);
423 return stack
? 0 : -ENOMEM
;
426 static void free_thread_stack(struct task_struct
*tsk
)
428 arch_free_thread_stack(tsk
);
432 #endif /* !CONFIG_ARCH_THREAD_STACK_ALLOCATOR */
434 /* SLAB cache for signal_struct structures (tsk->signal) */
435 static struct kmem_cache
*signal_cachep
;
437 /* SLAB cache for sighand_struct structures (tsk->sighand) */
438 struct kmem_cache
*sighand_cachep
;
440 /* SLAB cache for files_struct structures (tsk->files) */
441 struct kmem_cache
*files_cachep
;
443 /* SLAB cache for fs_struct structures (tsk->fs) */
444 struct kmem_cache
*fs_cachep
;
446 /* SLAB cache for vm_area_struct structures */
447 static struct kmem_cache
*vm_area_cachep
;
449 /* SLAB cache for mm_struct structures (tsk->mm) */
450 static struct kmem_cache
*mm_cachep
;
452 #ifdef CONFIG_PER_VMA_LOCK
454 /* SLAB cache for vm_area_struct.lock */
455 static struct kmem_cache
*vma_lock_cachep
;
457 static bool vma_lock_alloc(struct vm_area_struct
*vma
)
459 vma
->vm_lock
= kmem_cache_alloc(vma_lock_cachep
, GFP_KERNEL
);
463 init_rwsem(&vma
->vm_lock
->lock
);
464 vma
->vm_lock_seq
= -1;
469 static inline void vma_lock_free(struct vm_area_struct
*vma
)
471 kmem_cache_free(vma_lock_cachep
, vma
->vm_lock
);
474 #else /* CONFIG_PER_VMA_LOCK */
476 static inline bool vma_lock_alloc(struct vm_area_struct
*vma
) { return true; }
477 static inline void vma_lock_free(struct vm_area_struct
*vma
) {}
479 #endif /* CONFIG_PER_VMA_LOCK */
481 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
483 struct vm_area_struct
*vma
;
485 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
490 if (!vma_lock_alloc(vma
)) {
491 kmem_cache_free(vm_area_cachep
, vma
);
498 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
500 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
505 ASSERT_EXCLUSIVE_WRITER(orig
->vm_flags
);
506 ASSERT_EXCLUSIVE_WRITER(orig
->vm_file
);
508 * orig->shared.rb may be modified concurrently, but the clone
509 * will be reinitialized.
511 data_race(memcpy(new, orig
, sizeof(*new)));
512 if (!vma_lock_alloc(new)) {
513 kmem_cache_free(vm_area_cachep
, new);
516 INIT_LIST_HEAD(&new->anon_vma_chain
);
517 vma_numab_state_init(new);
518 dup_anon_vma_name(orig
, new);
523 void __vm_area_free(struct vm_area_struct
*vma
)
525 vma_numab_state_free(vma
);
526 free_anon_vma_name(vma
);
528 kmem_cache_free(vm_area_cachep
, vma
);
531 #ifdef CONFIG_PER_VMA_LOCK
532 static void vm_area_free_rcu_cb(struct rcu_head
*head
)
534 struct vm_area_struct
*vma
= container_of(head
, struct vm_area_struct
,
537 /* The vma should not be locked while being destroyed. */
538 VM_BUG_ON_VMA(rwsem_is_locked(&vma
->vm_lock
->lock
), vma
);
543 void vm_area_free(struct vm_area_struct
*vma
)
545 #ifdef CONFIG_PER_VMA_LOCK
546 call_rcu(&vma
->vm_rcu
, vm_area_free_rcu_cb
);
552 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
554 if (IS_ENABLED(CONFIG_VMAP_STACK
)) {
555 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
558 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
559 mod_lruvec_page_state(vm
->pages
[i
], NR_KERNEL_STACK_KB
,
560 account
* (PAGE_SIZE
/ 1024));
562 void *stack
= task_stack_page(tsk
);
564 /* All stack pages are in the same node. */
565 mod_lruvec_kmem_state(stack
, NR_KERNEL_STACK_KB
,
566 account
* (THREAD_SIZE
/ 1024));
570 void exit_task_stack_account(struct task_struct
*tsk
)
572 account_kernel_stack(tsk
, -1);
574 if (IS_ENABLED(CONFIG_VMAP_STACK
)) {
575 struct vm_struct
*vm
;
578 vm
= task_stack_vm_area(tsk
);
579 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++)
580 memcg_kmem_uncharge_page(vm
->pages
[i
], 0);
584 static void release_task_stack(struct task_struct
*tsk
)
586 if (WARN_ON(READ_ONCE(tsk
->__state
) != TASK_DEAD
))
587 return; /* Better to leak the stack than to free prematurely */
589 free_thread_stack(tsk
);
592 #ifdef CONFIG_THREAD_INFO_IN_TASK
593 void put_task_stack(struct task_struct
*tsk
)
595 if (refcount_dec_and_test(&tsk
->stack_refcount
))
596 release_task_stack(tsk
);
600 void free_task(struct task_struct
*tsk
)
602 #ifdef CONFIG_SECCOMP
603 WARN_ON_ONCE(tsk
->seccomp
.filter
);
605 release_user_cpus_ptr(tsk
);
608 #ifndef CONFIG_THREAD_INFO_IN_TASK
610 * The task is finally done with both the stack and thread_info,
613 release_task_stack(tsk
);
616 * If the task had a separate stack allocation, it should be gone
619 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
621 rt_mutex_debug_task_free(tsk
);
622 ftrace_graph_exit_task(tsk
);
623 arch_release_task_struct(tsk
);
624 if (tsk
->flags
& PF_KTHREAD
)
625 free_kthread_struct(tsk
);
626 bpf_task_storage_free(tsk
);
627 free_task_struct(tsk
);
629 EXPORT_SYMBOL(free_task
);
631 static void dup_mm_exe_file(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
633 struct file
*exe_file
;
635 exe_file
= get_mm_exe_file(oldmm
);
636 RCU_INIT_POINTER(mm
->exe_file
, exe_file
);
638 * We depend on the oldmm having properly denied write access to the
641 if (exe_file
&& deny_write_access(exe_file
))
642 pr_warn_once("deny_write_access() failed in %s\n", __func__
);
646 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
647 struct mm_struct
*oldmm
)
649 struct vm_area_struct
*mpnt
, *tmp
;
651 unsigned long charge
= 0;
653 VMA_ITERATOR(old_vmi
, oldmm
, 0);
654 VMA_ITERATOR(vmi
, mm
, 0);
656 uprobe_start_dup_mmap();
657 if (mmap_write_lock_killable(oldmm
)) {
659 goto fail_uprobe_end
;
661 flush_cache_dup_mm(oldmm
);
662 uprobe_dup_mmap(oldmm
, mm
);
664 * Not linked in yet - no deadlock potential:
666 mmap_write_lock_nested(mm
, SINGLE_DEPTH_NESTING
);
668 /* No ordering required: file already has been exposed. */
669 dup_mm_exe_file(mm
, oldmm
);
671 mm
->total_vm
= oldmm
->total_vm
;
672 mm
->data_vm
= oldmm
->data_vm
;
673 mm
->exec_vm
= oldmm
->exec_vm
;
674 mm
->stack_vm
= oldmm
->stack_vm
;
676 retval
= ksm_fork(mm
, oldmm
);
679 khugepaged_fork(mm
, oldmm
);
681 retval
= vma_iter_bulk_alloc(&vmi
, oldmm
->map_count
);
685 mt_clear_in_rcu(vmi
.mas
.tree
);
686 for_each_vma(old_vmi
, mpnt
) {
689 vma_start_write(mpnt
);
690 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
691 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
696 * Don't duplicate many vmas if we've been oom-killed (for
699 if (fatal_signal_pending(current
)) {
703 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
704 unsigned long len
= vma_pages(mpnt
);
706 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
710 tmp
= vm_area_dup(mpnt
);
713 retval
= vma_dup_policy(mpnt
, tmp
);
715 goto fail_nomem_policy
;
717 retval
= dup_userfaultfd(tmp
, &uf
);
719 goto fail_nomem_anon_vma_fork
;
720 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
722 * VM_WIPEONFORK gets a clean slate in the child.
723 * Don't prepare anon_vma until fault since we don't
724 * copy page for current vma.
726 tmp
->anon_vma
= NULL
;
727 } else if (anon_vma_fork(tmp
, mpnt
))
728 goto fail_nomem_anon_vma_fork
;
729 vm_flags_clear(tmp
, VM_LOCKED_MASK
);
732 struct address_space
*mapping
= file
->f_mapping
;
735 i_mmap_lock_write(mapping
);
736 if (tmp
->vm_flags
& VM_SHARED
)
737 mapping_allow_writable(mapping
);
738 flush_dcache_mmap_lock(mapping
);
739 /* insert tmp into the share list, just after mpnt */
740 vma_interval_tree_insert_after(tmp
, mpnt
,
742 flush_dcache_mmap_unlock(mapping
);
743 i_mmap_unlock_write(mapping
);
747 * Copy/update hugetlb private vma information.
749 if (is_vm_hugetlb_page(tmp
))
750 hugetlb_dup_vma_private(tmp
);
752 /* Link the vma into the MT */
753 if (vma_iter_bulk_store(&vmi
, tmp
))
754 goto fail_nomem_vmi_store
;
757 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
758 retval
= copy_page_range(tmp
, mpnt
);
760 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
761 tmp
->vm_ops
->open(tmp
);
766 /* a new mm has just been created */
767 retval
= arch_dup_mmap(oldmm
, mm
);
771 mt_set_in_rcu(vmi
.mas
.tree
);
773 mmap_write_unlock(mm
);
775 mmap_write_unlock(oldmm
);
776 dup_userfaultfd_complete(&uf
);
778 uprobe_end_dup_mmap();
781 fail_nomem_vmi_store
:
782 unlink_anon_vmas(tmp
);
783 fail_nomem_anon_vma_fork
:
784 mpol_put(vma_policy(tmp
));
789 vm_unacct_memory(charge
);
793 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
795 mm
->pgd
= pgd_alloc(mm
);
796 if (unlikely(!mm
->pgd
))
801 static inline void mm_free_pgd(struct mm_struct
*mm
)
803 pgd_free(mm
, mm
->pgd
);
806 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
808 mmap_write_lock(oldmm
);
809 dup_mm_exe_file(mm
, oldmm
);
810 mmap_write_unlock(oldmm
);
813 #define mm_alloc_pgd(mm) (0)
814 #define mm_free_pgd(mm)
815 #endif /* CONFIG_MMU */
817 static void check_mm(struct mm_struct
*mm
)
821 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types
) != NR_MM_COUNTERS
,
822 "Please make sure 'struct resident_page_types[]' is updated as well");
824 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
825 long x
= percpu_counter_sum(&mm
->rss_stat
[i
]);
828 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
829 mm
, resident_page_types
[i
], x
);
832 if (mm_pgtables_bytes(mm
))
833 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
834 mm_pgtables_bytes(mm
));
836 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
837 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
841 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
842 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
844 static void do_check_lazy_tlb(void *arg
)
846 struct mm_struct
*mm
= arg
;
848 WARN_ON_ONCE(current
->active_mm
== mm
);
851 static void do_shoot_lazy_tlb(void *arg
)
853 struct mm_struct
*mm
= arg
;
855 if (current
->active_mm
== mm
) {
856 WARN_ON_ONCE(current
->mm
);
857 current
->active_mm
= &init_mm
;
858 switch_mm(mm
, &init_mm
, current
);
862 static void cleanup_lazy_tlbs(struct mm_struct
*mm
)
864 if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN
)) {
866 * In this case, lazy tlb mms are refounted and would not reach
867 * __mmdrop until all CPUs have switched away and mmdrop()ed.
873 * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it
874 * requires lazy mm users to switch to another mm when the refcount
875 * drops to zero, before the mm is freed. This requires IPIs here to
876 * switch kernel threads to init_mm.
878 * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm
879 * switch with the final userspace teardown TLB flush which leaves the
880 * mm lazy on this CPU but no others, reducing the need for additional
881 * IPIs here. There are cases where a final IPI is still required here,
882 * such as the final mmdrop being performed on a different CPU than the
883 * one exiting, or kernel threads using the mm when userspace exits.
885 * IPI overheads have not found to be expensive, but they could be
886 * reduced in a number of possible ways, for example (roughly
887 * increasing order of complexity):
888 * - The last lazy reference created by exit_mm() could instead switch
889 * to init_mm, however it's probable this will run on the same CPU
890 * immediately afterwards, so this may not reduce IPIs much.
891 * - A batch of mms requiring IPIs could be gathered and freed at once.
892 * - CPUs store active_mm where it can be remotely checked without a
893 * lock, to filter out false-positives in the cpumask.
894 * - After mm_users or mm_count reaches zero, switching away from the
895 * mm could clear mm_cpumask to reduce some IPIs, perhaps together
896 * with some batching or delaying of the final IPIs.
897 * - A delayed freeing and RCU-like quiescing sequence based on mm
898 * switching to avoid IPIs completely.
900 on_each_cpu_mask(mm_cpumask(mm
), do_shoot_lazy_tlb
, (void *)mm
, 1);
901 if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES
))
902 on_each_cpu(do_check_lazy_tlb
, (void *)mm
, 1);
906 * Called when the last reference to the mm
907 * is dropped: either by a lazy thread or by
908 * mmput. Free the page directory and the mm.
910 void __mmdrop(struct mm_struct
*mm
)
912 BUG_ON(mm
== &init_mm
);
913 WARN_ON_ONCE(mm
== current
->mm
);
915 /* Ensure no CPUs are using this as their lazy tlb mm */
916 cleanup_lazy_tlbs(mm
);
918 WARN_ON_ONCE(mm
== current
->active_mm
);
921 mmu_notifier_subscriptions_destroy(mm
);
923 put_user_ns(mm
->user_ns
);
926 percpu_counter_destroy_many(mm
->rss_stat
, NR_MM_COUNTERS
);
930 EXPORT_SYMBOL_GPL(__mmdrop
);
932 static void mmdrop_async_fn(struct work_struct
*work
)
934 struct mm_struct
*mm
;
936 mm
= container_of(work
, struct mm_struct
, async_put_work
);
940 static void mmdrop_async(struct mm_struct
*mm
)
942 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
943 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
944 schedule_work(&mm
->async_put_work
);
948 static inline void free_signal_struct(struct signal_struct
*sig
)
950 taskstats_tgid_free(sig
);
951 sched_autogroup_exit(sig
);
953 * __mmdrop is not safe to call from softirq context on x86 due to
954 * pgd_dtor so postpone it to the async context
957 mmdrop_async(sig
->oom_mm
);
958 kmem_cache_free(signal_cachep
, sig
);
961 static inline void put_signal_struct(struct signal_struct
*sig
)
963 if (refcount_dec_and_test(&sig
->sigcnt
))
964 free_signal_struct(sig
);
967 void __put_task_struct(struct task_struct
*tsk
)
969 WARN_ON(!tsk
->exit_state
);
970 WARN_ON(refcount_read(&tsk
->usage
));
971 WARN_ON(tsk
== current
);
975 task_numa_free(tsk
, true);
976 security_task_free(tsk
);
978 delayacct_tsk_free(tsk
);
979 put_signal_struct(tsk
->signal
);
980 sched_core_free(tsk
);
983 EXPORT_SYMBOL_GPL(__put_task_struct
);
985 void __put_task_struct_rcu_cb(struct rcu_head
*rhp
)
987 struct task_struct
*task
= container_of(rhp
, struct task_struct
, rcu
);
989 __put_task_struct(task
);
991 EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb
);
993 void __init __weak
arch_task_cache_init(void) { }
998 static void set_max_threads(unsigned int max_threads_suggested
)
1001 unsigned long nr_pages
= totalram_pages();
1004 * The number of threads shall be limited such that the thread
1005 * structures may only consume a small part of the available memory.
1007 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
1008 threads
= MAX_THREADS
;
1010 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
1011 (u64
) THREAD_SIZE
* 8UL);
1013 if (threads
> max_threads_suggested
)
1014 threads
= max_threads_suggested
;
1016 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
1019 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
1020 /* Initialized by the architecture: */
1021 int arch_task_struct_size __read_mostly
;
1024 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
1025 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
1027 /* Fetch thread_struct whitelist for the architecture. */
1028 arch_thread_struct_whitelist(offset
, size
);
1031 * Handle zero-sized whitelist or empty thread_struct, otherwise
1032 * adjust offset to position of thread_struct in task_struct.
1034 if (unlikely(*size
== 0))
1037 *offset
+= offsetof(struct task_struct
, thread
);
1039 #endif /* CONFIG_ARCH_TASK_STRUCT_ALLOCATOR */
1041 void __init
fork_init(void)
1044 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
1045 #ifndef ARCH_MIN_TASKALIGN
1046 #define ARCH_MIN_TASKALIGN 0
1048 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
1049 unsigned long useroffset
, usersize
;
1051 /* create a slab on which task_structs can be allocated */
1052 task_struct_whitelist(&useroffset
, &usersize
);
1053 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
1054 arch_task_struct_size
, align
,
1055 SLAB_PANIC
|SLAB_ACCOUNT
,
1056 useroffset
, usersize
, NULL
);
1059 /* do the arch specific task caches init */
1060 arch_task_cache_init();
1062 set_max_threads(MAX_THREADS
);
1064 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
1065 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
1066 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
1067 init_task
.signal
->rlim
[RLIMIT_NPROC
];
1069 for (i
= 0; i
< UCOUNT_COUNTS
; i
++)
1070 init_user_ns
.ucount_max
[i
] = max_threads
/2;
1072 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_NPROC
, RLIM_INFINITY
);
1073 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_MSGQUEUE
, RLIM_INFINITY
);
1074 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_SIGPENDING
, RLIM_INFINITY
);
1075 set_userns_rlimit_max(&init_user_ns
, UCOUNT_RLIMIT_MEMLOCK
, RLIM_INFINITY
);
1077 #ifdef CONFIG_VMAP_STACK
1078 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
1079 NULL
, free_vm_stack_cache
);
1084 lockdep_init_task(&init_task
);
1088 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
1089 struct task_struct
*src
)
1095 void set_task_stack_end_magic(struct task_struct
*tsk
)
1097 unsigned long *stackend
;
1099 stackend
= end_of_stack(tsk
);
1100 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
1103 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
1105 struct task_struct
*tsk
;
1108 if (node
== NUMA_NO_NODE
)
1109 node
= tsk_fork_get_node(orig
);
1110 tsk
= alloc_task_struct_node(node
);
1114 err
= arch_dup_task_struct(tsk
, orig
);
1118 err
= alloc_thread_stack_node(tsk
, node
);
1122 #ifdef CONFIG_THREAD_INFO_IN_TASK
1123 refcount_set(&tsk
->stack_refcount
, 1);
1125 account_kernel_stack(tsk
, 1);
1127 err
= scs_prepare(tsk
, node
);
1131 #ifdef CONFIG_SECCOMP
1133 * We must handle setting up seccomp filters once we're under
1134 * the sighand lock in case orig has changed between now and
1135 * then. Until then, filter must be NULL to avoid messing up
1136 * the usage counts on the error path calling free_task.
1138 tsk
->seccomp
.filter
= NULL
;
1141 setup_thread_stack(tsk
, orig
);
1142 clear_user_return_notifier(tsk
);
1143 clear_tsk_need_resched(tsk
);
1144 set_task_stack_end_magic(tsk
);
1145 clear_syscall_work_syscall_user_dispatch(tsk
);
1147 #ifdef CONFIG_STACKPROTECTOR
1148 tsk
->stack_canary
= get_random_canary();
1150 if (orig
->cpus_ptr
== &orig
->cpus_mask
)
1151 tsk
->cpus_ptr
= &tsk
->cpus_mask
;
1152 dup_user_cpus_ptr(tsk
, orig
, node
);
1155 * One for the user space visible state that goes away when reaped.
1156 * One for the scheduler.
1158 refcount_set(&tsk
->rcu_users
, 2);
1159 /* One for the rcu users */
1160 refcount_set(&tsk
->usage
, 1);
1161 #ifdef CONFIG_BLK_DEV_IO_TRACE
1162 tsk
->btrace_seq
= 0;
1164 tsk
->splice_pipe
= NULL
;
1165 tsk
->task_frag
.page
= NULL
;
1166 tsk
->wake_q
.next
= NULL
;
1167 tsk
->worker_private
= NULL
;
1169 kcov_task_init(tsk
);
1170 kmsan_task_create(tsk
);
1171 kmap_local_fork(tsk
);
1173 #ifdef CONFIG_FAULT_INJECTION
1177 #ifdef CONFIG_BLK_CGROUP
1178 tsk
->throttle_disk
= NULL
;
1179 tsk
->use_memdelay
= 0;
1182 #ifdef CONFIG_IOMMU_SVA
1183 tsk
->pasid_activated
= 0;
1187 tsk
->active_memcg
= NULL
;
1190 #ifdef CONFIG_CPU_SUP_INTEL
1191 tsk
->reported_split_lock
= 0;
1194 #ifdef CONFIG_SCHED_MM_CID
1196 tsk
->last_mm_cid
= -1;
1197 tsk
->mm_cid_active
= 0;
1198 tsk
->migrate_from_cpu
= -1;
1203 exit_task_stack_account(tsk
);
1204 free_thread_stack(tsk
);
1206 free_task_struct(tsk
);
1210 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
1212 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
1214 static int __init
coredump_filter_setup(char *s
)
1216 default_dump_filter
=
1217 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
1218 MMF_DUMP_FILTER_MASK
;
1222 __setup("coredump_filter=", coredump_filter_setup
);
1224 #include <linux/init_task.h>
1226 static void mm_init_aio(struct mm_struct
*mm
)
1229 spin_lock_init(&mm
->ioctx_lock
);
1230 mm
->ioctx_table
= NULL
;
1234 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
1235 struct task_struct
*p
)
1239 WRITE_ONCE(mm
->owner
, NULL
);
1243 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1250 static void mm_init_uprobes_state(struct mm_struct
*mm
)
1252 #ifdef CONFIG_UPROBES
1253 mm
->uprobes_state
.xol_area
= NULL
;
1257 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
1258 struct user_namespace
*user_ns
)
1260 mt_init_flags(&mm
->mm_mt
, MM_MT_FLAGS
);
1261 mt_set_external_lock(&mm
->mm_mt
, &mm
->mmap_lock
);
1262 atomic_set(&mm
->mm_users
, 1);
1263 atomic_set(&mm
->mm_count
, 1);
1264 seqcount_init(&mm
->write_protect_seq
);
1266 INIT_LIST_HEAD(&mm
->mmlist
);
1267 #ifdef CONFIG_PER_VMA_LOCK
1268 mm
->mm_lock_seq
= 0;
1270 mm_pgtables_bytes_init(mm
);
1273 atomic64_set(&mm
->pinned_vm
, 0);
1274 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
1275 spin_lock_init(&mm
->page_table_lock
);
1276 spin_lock_init(&mm
->arg_lock
);
1277 mm_init_cpumask(mm
);
1279 mm_init_owner(mm
, p
);
1281 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1282 mmu_notifier_subscriptions_init(mm
);
1283 init_tlb_flush_pending(mm
);
1284 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1285 mm
->pmd_huge_pte
= NULL
;
1287 mm_init_uprobes_state(mm
);
1288 hugetlb_count_init(mm
);
1291 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1292 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1294 mm
->flags
= default_dump_filter
;
1298 if (mm_alloc_pgd(mm
))
1301 if (init_new_context(p
, mm
))
1302 goto fail_nocontext
;
1304 if (mm_alloc_cid(mm
))
1307 if (percpu_counter_init_many(mm
->rss_stat
, 0, GFP_KERNEL_ACCOUNT
,
1311 mm
->user_ns
= get_user_ns(user_ns
);
1312 lru_gen_init_mm(mm
);
1318 destroy_context(mm
);
1327 * Allocate and initialize an mm_struct.
1329 struct mm_struct
*mm_alloc(void)
1331 struct mm_struct
*mm
;
1337 memset(mm
, 0, sizeof(*mm
));
1338 return mm_init(mm
, current
, current_user_ns());
1341 static inline void __mmput(struct mm_struct
*mm
)
1343 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1345 uprobe_clear_state(mm
);
1348 khugepaged_exit(mm
); /* must run before exit_mmap */
1350 mm_put_huge_zero_page(mm
);
1351 set_mm_exe_file(mm
, NULL
);
1352 if (!list_empty(&mm
->mmlist
)) {
1353 spin_lock(&mmlist_lock
);
1354 list_del(&mm
->mmlist
);
1355 spin_unlock(&mmlist_lock
);
1358 module_put(mm
->binfmt
->module
);
1364 * Decrement the use count and release all resources for an mm.
1366 void mmput(struct mm_struct
*mm
)
1370 if (atomic_dec_and_test(&mm
->mm_users
))
1373 EXPORT_SYMBOL_GPL(mmput
);
1376 static void mmput_async_fn(struct work_struct
*work
)
1378 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1384 void mmput_async(struct mm_struct
*mm
)
1386 if (atomic_dec_and_test(&mm
->mm_users
)) {
1387 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1388 schedule_work(&mm
->async_put_work
);
1391 EXPORT_SYMBOL_GPL(mmput_async
);
1395 * set_mm_exe_file - change a reference to the mm's executable file
1397 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1399 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1400 * invocations: in mmput() nobody alive left, in execve it happens before
1401 * the new mm is made visible to anyone.
1403 * Can only fail if new_exe_file != NULL.
1405 int set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1407 struct file
*old_exe_file
;
1410 * It is safe to dereference the exe_file without RCU as
1411 * this function is only called if nobody else can access
1412 * this mm -- see comment above for justification.
1414 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1418 * We expect the caller (i.e., sys_execve) to already denied
1419 * write access, so this is unlikely to fail.
1421 if (unlikely(deny_write_access(new_exe_file
)))
1423 get_file(new_exe_file
);
1425 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1427 allow_write_access(old_exe_file
);
1434 * replace_mm_exe_file - replace a reference to the mm's executable file
1436 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1438 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1440 int replace_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1442 struct vm_area_struct
*vma
;
1443 struct file
*old_exe_file
;
1446 /* Forbid mm->exe_file change if old file still mapped. */
1447 old_exe_file
= get_mm_exe_file(mm
);
1449 VMA_ITERATOR(vmi
, mm
, 0);
1451 for_each_vma(vmi
, vma
) {
1454 if (path_equal(&vma
->vm_file
->f_path
,
1455 &old_exe_file
->f_path
)) {
1460 mmap_read_unlock(mm
);
1466 ret
= deny_write_access(new_exe_file
);
1469 get_file(new_exe_file
);
1471 /* set the new file */
1472 mmap_write_lock(mm
);
1473 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1474 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1475 mmap_write_unlock(mm
);
1478 allow_write_access(old_exe_file
);
1485 * get_mm_exe_file - acquire a reference to the mm's executable file
1487 * Returns %NULL if mm has no associated executable file.
1488 * User must release file via fput().
1490 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1492 struct file
*exe_file
;
1495 exe_file
= rcu_dereference(mm
->exe_file
);
1496 if (exe_file
&& !get_file_rcu(exe_file
))
1503 * get_task_exe_file - acquire a reference to the task's executable file
1505 * Returns %NULL if task's mm (if any) has no associated executable file or
1506 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1507 * User must release file via fput().
1509 struct file
*get_task_exe_file(struct task_struct
*task
)
1511 struct file
*exe_file
= NULL
;
1512 struct mm_struct
*mm
;
1517 if (!(task
->flags
& PF_KTHREAD
))
1518 exe_file
= get_mm_exe_file(mm
);
1525 * get_task_mm - acquire a reference to the task's mm
1527 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1528 * this kernel workthread has transiently adopted a user mm with use_mm,
1529 * to do its AIO) is not set and if so returns a reference to it, after
1530 * bumping up the use count. User must release the mm via mmput()
1531 * after use. Typically used by /proc and ptrace.
1533 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1535 struct mm_struct
*mm
;
1540 if (task
->flags
& PF_KTHREAD
)
1548 EXPORT_SYMBOL_GPL(get_task_mm
);
1550 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1552 struct mm_struct
*mm
;
1555 err
= down_read_killable(&task
->signal
->exec_update_lock
);
1557 return ERR_PTR(err
);
1559 mm
= get_task_mm(task
);
1560 if (mm
&& mm
!= current
->mm
&&
1561 !ptrace_may_access(task
, mode
)) {
1563 mm
= ERR_PTR(-EACCES
);
1565 up_read(&task
->signal
->exec_update_lock
);
1570 static void complete_vfork_done(struct task_struct
*tsk
)
1572 struct completion
*vfork
;
1575 vfork
= tsk
->vfork_done
;
1576 if (likely(vfork
)) {
1577 tsk
->vfork_done
= NULL
;
1583 static int wait_for_vfork_done(struct task_struct
*child
,
1584 struct completion
*vfork
)
1586 unsigned int state
= TASK_UNINTERRUPTIBLE
|TASK_KILLABLE
|TASK_FREEZABLE
;
1589 cgroup_enter_frozen();
1590 killed
= wait_for_completion_state(vfork
, state
);
1591 cgroup_leave_frozen(false);
1595 child
->vfork_done
= NULL
;
1599 put_task_struct(child
);
1603 /* Please note the differences between mmput and mm_release.
1604 * mmput is called whenever we stop holding onto a mm_struct,
1605 * error success whatever.
1607 * mm_release is called after a mm_struct has been removed
1608 * from the current process.
1610 * This difference is important for error handling, when we
1611 * only half set up a mm_struct for a new process and need to restore
1612 * the old one. Because we mmput the new mm_struct before
1613 * restoring the old one. . .
1614 * Eric Biederman 10 January 1998
1616 static void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1618 uprobe_free_utask(tsk
);
1620 /* Get rid of any cached register state */
1621 deactivate_mm(tsk
, mm
);
1624 * Signal userspace if we're not exiting with a core dump
1625 * because we want to leave the value intact for debugging
1628 if (tsk
->clear_child_tid
) {
1629 if (atomic_read(&mm
->mm_users
) > 1) {
1631 * We don't check the error code - if userspace has
1632 * not set up a proper pointer then tough luck.
1634 put_user(0, tsk
->clear_child_tid
);
1635 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1636 1, NULL
, NULL
, 0, 0);
1638 tsk
->clear_child_tid
= NULL
;
1642 * All done, finally we can wake up parent and return this mm to him.
1643 * Also kthread_stop() uses this completion for synchronization.
1645 if (tsk
->vfork_done
)
1646 complete_vfork_done(tsk
);
1649 void exit_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1651 futex_exit_release(tsk
);
1652 mm_release(tsk
, mm
);
1655 void exec_mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1657 futex_exec_release(tsk
);
1658 mm_release(tsk
, mm
);
1662 * dup_mm() - duplicates an existing mm structure
1663 * @tsk: the task_struct with which the new mm will be associated.
1664 * @oldmm: the mm to duplicate.
1666 * Allocates a new mm structure and duplicates the provided @oldmm structure
1669 * Return: the duplicated mm or NULL on failure.
1671 static struct mm_struct
*dup_mm(struct task_struct
*tsk
,
1672 struct mm_struct
*oldmm
)
1674 struct mm_struct
*mm
;
1681 memcpy(mm
, oldmm
, sizeof(*mm
));
1683 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1686 err
= dup_mmap(mm
, oldmm
);
1690 mm
->hiwater_rss
= get_mm_rss(mm
);
1691 mm
->hiwater_vm
= mm
->total_vm
;
1693 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1699 /* don't put binfmt in mmput, we haven't got module yet */
1701 mm_init_owner(mm
, NULL
);
1708 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1710 struct mm_struct
*mm
, *oldmm
;
1712 tsk
->min_flt
= tsk
->maj_flt
= 0;
1713 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1714 #ifdef CONFIG_DETECT_HUNG_TASK
1715 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1716 tsk
->last_switch_time
= 0;
1720 tsk
->active_mm
= NULL
;
1723 * Are we cloning a kernel thread?
1725 * We need to steal a active VM for that..
1727 oldmm
= current
->mm
;
1731 if (clone_flags
& CLONE_VM
) {
1735 mm
= dup_mm(tsk
, current
->mm
);
1741 tsk
->active_mm
= mm
;
1742 sched_mm_cid_fork(tsk
);
1746 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1748 struct fs_struct
*fs
= current
->fs
;
1749 if (clone_flags
& CLONE_FS
) {
1750 /* tsk->fs is already what we want */
1751 spin_lock(&fs
->lock
);
1753 spin_unlock(&fs
->lock
);
1757 spin_unlock(&fs
->lock
);
1760 tsk
->fs
= copy_fs_struct(fs
);
1766 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
,
1769 struct files_struct
*oldf
, *newf
;
1773 * A background process may not have any files ...
1775 oldf
= current
->files
;
1784 if (clone_flags
& CLONE_FILES
) {
1785 atomic_inc(&oldf
->count
);
1789 newf
= dup_fd(oldf
, NR_OPEN_MAX
, &error
);
1799 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1801 struct sighand_struct
*sig
;
1803 if (clone_flags
& CLONE_SIGHAND
) {
1804 refcount_inc(¤t
->sighand
->count
);
1807 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1808 RCU_INIT_POINTER(tsk
->sighand
, sig
);
1812 refcount_set(&sig
->count
, 1);
1813 spin_lock_irq(¤t
->sighand
->siglock
);
1814 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1815 spin_unlock_irq(¤t
->sighand
->siglock
);
1817 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1818 if (clone_flags
& CLONE_CLEAR_SIGHAND
)
1819 flush_signal_handlers(tsk
, 0);
1824 void __cleanup_sighand(struct sighand_struct
*sighand
)
1826 if (refcount_dec_and_test(&sighand
->count
)) {
1827 signalfd_cleanup(sighand
);
1829 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1830 * without an RCU grace period, see __lock_task_sighand().
1832 kmem_cache_free(sighand_cachep
, sighand
);
1837 * Initialize POSIX timer handling for a thread group.
1839 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1841 struct posix_cputimers
*pct
= &sig
->posix_cputimers
;
1842 unsigned long cpu_limit
;
1844 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1845 posix_cputimers_group_init(pct
, cpu_limit
);
1848 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1850 struct signal_struct
*sig
;
1852 if (clone_flags
& CLONE_THREAD
)
1855 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1860 sig
->nr_threads
= 1;
1861 sig
->quick_threads
= 1;
1862 atomic_set(&sig
->live
, 1);
1863 refcount_set(&sig
->sigcnt
, 1);
1865 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1866 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1867 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1869 init_waitqueue_head(&sig
->wait_chldexit
);
1870 sig
->curr_target
= tsk
;
1871 init_sigpending(&sig
->shared_pending
);
1872 INIT_HLIST_HEAD(&sig
->multiprocess
);
1873 seqlock_init(&sig
->stats_lock
);
1874 prev_cputime_init(&sig
->prev_cputime
);
1876 #ifdef CONFIG_POSIX_TIMERS
1877 INIT_LIST_HEAD(&sig
->posix_timers
);
1878 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1879 sig
->real_timer
.function
= it_real_fn
;
1882 task_lock(current
->group_leader
);
1883 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1884 task_unlock(current
->group_leader
);
1886 posix_cpu_timers_init_group(sig
);
1888 tty_audit_fork(sig
);
1889 sched_autogroup_fork(sig
);
1891 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1892 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1894 mutex_init(&sig
->cred_guard_mutex
);
1895 init_rwsem(&sig
->exec_update_lock
);
1900 static void copy_seccomp(struct task_struct
*p
)
1902 #ifdef CONFIG_SECCOMP
1904 * Must be called with sighand->lock held, which is common to
1905 * all threads in the group. Holding cred_guard_mutex is not
1906 * needed because this new task is not yet running and cannot
1909 assert_spin_locked(¤t
->sighand
->siglock
);
1911 /* Ref-count the new filter user, and assign it. */
1912 get_seccomp_filter(current
);
1913 p
->seccomp
= current
->seccomp
;
1916 * Explicitly enable no_new_privs here in case it got set
1917 * between the task_struct being duplicated and holding the
1918 * sighand lock. The seccomp state and nnp must be in sync.
1920 if (task_no_new_privs(current
))
1921 task_set_no_new_privs(p
);
1924 * If the parent gained a seccomp mode after copying thread
1925 * flags and between before we held the sighand lock, we have
1926 * to manually enable the seccomp thread flag here.
1928 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1929 set_task_syscall_work(p
, SECCOMP
);
1933 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1935 current
->clear_child_tid
= tidptr
;
1937 return task_pid_vnr(current
);
1940 static void rt_mutex_init_task(struct task_struct
*p
)
1942 raw_spin_lock_init(&p
->pi_lock
);
1943 #ifdef CONFIG_RT_MUTEXES
1944 p
->pi_waiters
= RB_ROOT_CACHED
;
1945 p
->pi_top_task
= NULL
;
1946 p
->pi_blocked_on
= NULL
;
1950 static inline void init_task_pid_links(struct task_struct
*task
)
1954 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
)
1955 INIT_HLIST_NODE(&task
->pid_links
[type
]);
1959 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1961 if (type
== PIDTYPE_PID
)
1962 task
->thread_pid
= pid
;
1964 task
->signal
->pids
[type
] = pid
;
1967 static inline void rcu_copy_process(struct task_struct
*p
)
1969 #ifdef CONFIG_PREEMPT_RCU
1970 p
->rcu_read_lock_nesting
= 0;
1971 p
->rcu_read_unlock_special
.s
= 0;
1972 p
->rcu_blocked_node
= NULL
;
1973 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1974 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1975 #ifdef CONFIG_TASKS_RCU
1976 p
->rcu_tasks_holdout
= false;
1977 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1978 p
->rcu_tasks_idle_cpu
= -1;
1979 #endif /* #ifdef CONFIG_TASKS_RCU */
1980 #ifdef CONFIG_TASKS_TRACE_RCU
1981 p
->trc_reader_nesting
= 0;
1982 p
->trc_reader_special
.s
= 0;
1983 INIT_LIST_HEAD(&p
->trc_holdout_list
);
1984 INIT_LIST_HEAD(&p
->trc_blkd_node
);
1985 #endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1988 struct pid
*pidfd_pid(const struct file
*file
)
1990 if (file
->f_op
== &pidfd_fops
)
1991 return file
->private_data
;
1993 return ERR_PTR(-EBADF
);
1996 static int pidfd_release(struct inode
*inode
, struct file
*file
)
1998 struct pid
*pid
= file
->private_data
;
2000 file
->private_data
= NULL
;
2005 #ifdef CONFIG_PROC_FS
2007 * pidfd_show_fdinfo - print information about a pidfd
2008 * @m: proc fdinfo file
2009 * @f: file referencing a pidfd
2012 * This function will print the pid that a given pidfd refers to in the
2013 * pid namespace of the procfs instance.
2014 * If the pid namespace of the process is not a descendant of the pid
2015 * namespace of the procfs instance 0 will be shown as its pid. This is
2016 * similar to calling getppid() on a process whose parent is outside of
2017 * its pid namespace.
2020 * If pid namespaces are supported then this function will also print
2021 * the pid of a given pidfd refers to for all descendant pid namespaces
2022 * starting from the current pid namespace of the instance, i.e. the
2023 * Pid field and the first entry in the NSpid field will be identical.
2024 * If the pid namespace of the process is not a descendant of the pid
2025 * namespace of the procfs instance 0 will be shown as its first NSpid
2026 * entry and no others will be shown.
2027 * Note that this differs from the Pid and NSpid fields in
2028 * /proc/<pid>/status where Pid and NSpid are always shown relative to
2029 * the pid namespace of the procfs instance. The difference becomes
2030 * obvious when sending around a pidfd between pid namespaces from a
2031 * different branch of the tree, i.e. where no ancestral relation is
2032 * present between the pid namespaces:
2033 * - create two new pid namespaces ns1 and ns2 in the initial pid
2034 * namespace (also take care to create new mount namespaces in the
2035 * new pid namespace and mount procfs)
2036 * - create a process with a pidfd in ns1
2037 * - send pidfd from ns1 to ns2
2038 * - read /proc/self/fdinfo/<pidfd> and observe that both Pid and NSpid
2039 * have exactly one entry, which is 0
2041 static void pidfd_show_fdinfo(struct seq_file
*m
, struct file
*f
)
2043 struct pid
*pid
= f
->private_data
;
2044 struct pid_namespace
*ns
;
2047 if (likely(pid_has_task(pid
, PIDTYPE_PID
))) {
2048 ns
= proc_pid_ns(file_inode(m
->file
)->i_sb
);
2049 nr
= pid_nr_ns(pid
, ns
);
2052 seq_put_decimal_ll(m
, "Pid:\t", nr
);
2054 #ifdef CONFIG_PID_NS
2055 seq_put_decimal_ll(m
, "\nNSpid:\t", nr
);
2059 /* If nr is non-zero it means that 'pid' is valid and that
2060 * ns, i.e. the pid namespace associated with the procfs
2061 * instance, is in the pid namespace hierarchy of pid.
2062 * Start at one below the already printed level.
2064 for (i
= ns
->level
+ 1; i
<= pid
->level
; i
++)
2065 seq_put_decimal_ll(m
, "\t", pid
->numbers
[i
].nr
);
2073 * Poll support for process exit notification.
2075 static __poll_t
pidfd_poll(struct file
*file
, struct poll_table_struct
*pts
)
2077 struct pid
*pid
= file
->private_data
;
2078 __poll_t poll_flags
= 0;
2080 poll_wait(file
, &pid
->wait_pidfd
, pts
);
2083 * Inform pollers only when the whole thread group exits.
2084 * If the thread group leader exits before all other threads in the
2085 * group, then poll(2) should block, similar to the wait(2) family.
2087 if (thread_group_exited(pid
))
2088 poll_flags
= EPOLLIN
| EPOLLRDNORM
;
2093 const struct file_operations pidfd_fops
= {
2094 .release
= pidfd_release
,
2096 #ifdef CONFIG_PROC_FS
2097 .show_fdinfo
= pidfd_show_fdinfo
,
2102 * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2103 * @pid: the struct pid for which to create a pidfd
2104 * @flags: flags of the new @pidfd
2105 * @pidfd: the pidfd to return
2107 * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2108 * caller's file descriptor table. The pidfd is reserved but not installed yet.
2110 * The helper doesn't perform checks on @pid which makes it useful for pidfds
2111 * created via CLONE_PIDFD where @pid has no task attached when the pidfd and
2112 * pidfd file are prepared.
2114 * If this function returns successfully the caller is responsible to either
2115 * call fd_install() passing the returned pidfd and pidfd file as arguments in
2116 * order to install the pidfd into its file descriptor table or they must use
2117 * put_unused_fd() and fput() on the returned pidfd and pidfd file
2120 * This function is useful when a pidfd must already be reserved but there
2121 * might still be points of failure afterwards and the caller wants to ensure
2122 * that no pidfd is leaked into its file descriptor table.
2124 * Return: On success, a reserved pidfd is returned from the function and a new
2125 * pidfd file is returned in the last argument to the function. On
2126 * error, a negative error code is returned from the function and the
2127 * last argument remains unchanged.
2129 static int __pidfd_prepare(struct pid
*pid
, unsigned int flags
, struct file
**ret
)
2132 struct file
*pidfd_file
;
2134 if (flags
& ~(O_NONBLOCK
| O_RDWR
| O_CLOEXEC
))
2137 pidfd
= get_unused_fd_flags(O_RDWR
| O_CLOEXEC
);
2141 pidfd_file
= anon_inode_getfile("[pidfd]", &pidfd_fops
, pid
,
2142 flags
| O_RDWR
| O_CLOEXEC
);
2143 if (IS_ERR(pidfd_file
)) {
2144 put_unused_fd(pidfd
);
2145 return PTR_ERR(pidfd_file
);
2147 get_pid(pid
); /* held by pidfd_file now */
2153 * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2154 * @pid: the struct pid for which to create a pidfd
2155 * @flags: flags of the new @pidfd
2156 * @pidfd: the pidfd to return
2158 * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2159 * caller's file descriptor table. The pidfd is reserved but not installed yet.
2161 * The helper verifies that @pid is used as a thread group leader.
2163 * If this function returns successfully the caller is responsible to either
2164 * call fd_install() passing the returned pidfd and pidfd file as arguments in
2165 * order to install the pidfd into its file descriptor table or they must use
2166 * put_unused_fd() and fput() on the returned pidfd and pidfd file
2169 * This function is useful when a pidfd must already be reserved but there
2170 * might still be points of failure afterwards and the caller wants to ensure
2171 * that no pidfd is leaked into its file descriptor table.
2173 * Return: On success, a reserved pidfd is returned from the function and a new
2174 * pidfd file is returned in the last argument to the function. On
2175 * error, a negative error code is returned from the function and the
2176 * last argument remains unchanged.
2178 int pidfd_prepare(struct pid
*pid
, unsigned int flags
, struct file
**ret
)
2180 if (!pid
|| !pid_has_task(pid
, PIDTYPE_TGID
))
2183 return __pidfd_prepare(pid
, flags
, ret
);
2186 static void __delayed_free_task(struct rcu_head
*rhp
)
2188 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
2193 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
2195 if (IS_ENABLED(CONFIG_MEMCG
))
2196 call_rcu(&tsk
->rcu
, __delayed_free_task
);
2201 static void copy_oom_score_adj(u64 clone_flags
, struct task_struct
*tsk
)
2203 /* Skip if kernel thread */
2207 /* Skip if spawning a thread or using vfork */
2208 if ((clone_flags
& (CLONE_VM
| CLONE_THREAD
| CLONE_VFORK
)) != CLONE_VM
)
2211 /* We need to synchronize with __set_oom_adj */
2212 mutex_lock(&oom_adj_mutex
);
2213 set_bit(MMF_MULTIPROCESS
, &tsk
->mm
->flags
);
2214 /* Update the values in case they were changed after copy_signal */
2215 tsk
->signal
->oom_score_adj
= current
->signal
->oom_score_adj
;
2216 tsk
->signal
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
2217 mutex_unlock(&oom_adj_mutex
);
2221 static void rv_task_fork(struct task_struct
*p
)
2225 for (i
= 0; i
< RV_PER_TASK_MONITORS
; i
++)
2226 p
->rv
[i
].da_mon
.monitoring
= false;
2229 #define rv_task_fork(p) do {} while (0)
2233 * This creates a new process as a copy of the old one,
2234 * but does not actually start it yet.
2236 * It copies the registers, and all the appropriate
2237 * parts of the process environment (as per the clone
2238 * flags). The actual kick-off is left to the caller.
2240 __latent_entropy
struct task_struct
*copy_process(
2244 struct kernel_clone_args
*args
)
2246 int pidfd
= -1, retval
;
2247 struct task_struct
*p
;
2248 struct multiprocess_signals delayed
;
2249 struct file
*pidfile
= NULL
;
2250 const u64 clone_flags
= args
->flags
;
2251 struct nsproxy
*nsp
= current
->nsproxy
;
2254 * Don't allow sharing the root directory with processes in a different
2257 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
2258 return ERR_PTR(-EINVAL
);
2260 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
2261 return ERR_PTR(-EINVAL
);
2264 * Thread groups must share signals as well, and detached threads
2265 * can only be started up within the thread group.
2267 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
2268 return ERR_PTR(-EINVAL
);
2271 * Shared signal handlers imply shared VM. By way of the above,
2272 * thread groups also imply shared VM. Blocking this case allows
2273 * for various simplifications in other code.
2275 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
2276 return ERR_PTR(-EINVAL
);
2279 * Siblings of global init remain as zombies on exit since they are
2280 * not reaped by their parent (swapper). To solve this and to avoid
2281 * multi-rooted process trees, prevent global and container-inits
2282 * from creating siblings.
2284 if ((clone_flags
& CLONE_PARENT
) &&
2285 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
2286 return ERR_PTR(-EINVAL
);
2289 * If the new process will be in a different pid or user namespace
2290 * do not allow it to share a thread group with the forking task.
2292 if (clone_flags
& CLONE_THREAD
) {
2293 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
2294 (task_active_pid_ns(current
) != nsp
->pid_ns_for_children
))
2295 return ERR_PTR(-EINVAL
);
2298 if (clone_flags
& CLONE_PIDFD
) {
2300 * - CLONE_DETACHED is blocked so that we can potentially
2301 * reuse it later for CLONE_PIDFD.
2302 * - CLONE_THREAD is blocked until someone really needs it.
2304 if (clone_flags
& (CLONE_DETACHED
| CLONE_THREAD
))
2305 return ERR_PTR(-EINVAL
);
2309 * Force any signals received before this point to be delivered
2310 * before the fork happens. Collect up signals sent to multiple
2311 * processes that happen during the fork and delay them so that
2312 * they appear to happen after the fork.
2314 sigemptyset(&delayed
.signal
);
2315 INIT_HLIST_NODE(&delayed
.node
);
2317 spin_lock_irq(¤t
->sighand
->siglock
);
2318 if (!(clone_flags
& CLONE_THREAD
))
2319 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
2320 recalc_sigpending();
2321 spin_unlock_irq(¤t
->sighand
->siglock
);
2322 retval
= -ERESTARTNOINTR
;
2323 if (task_sigpending(current
))
2327 p
= dup_task_struct(current
, node
);
2330 p
->flags
&= ~PF_KTHREAD
;
2332 p
->flags
|= PF_KTHREAD
;
2333 if (args
->user_worker
) {
2335 * Mark us a user worker, and block any signal that isn't
2338 p
->flags
|= PF_USER_WORKER
;
2339 siginitsetinv(&p
->blocked
, sigmask(SIGKILL
)|sigmask(SIGSTOP
));
2341 if (args
->io_thread
)
2342 p
->flags
|= PF_IO_WORKER
;
2345 strscpy_pad(p
->comm
, args
->name
, sizeof(p
->comm
));
2347 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? args
->child_tid
: NULL
;
2349 * Clear TID on mm_release()?
2351 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? args
->child_tid
: NULL
;
2353 ftrace_graph_init_task(p
);
2355 rt_mutex_init_task(p
);
2357 lockdep_assert_irqs_enabled();
2358 #ifdef CONFIG_PROVE_LOCKING
2359 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
2361 retval
= copy_creds(p
, clone_flags
);
2366 if (is_rlimit_overlimit(task_ucounts(p
), UCOUNT_RLIMIT_NPROC
, rlimit(RLIMIT_NPROC
))) {
2367 if (p
->real_cred
->user
!= INIT_USER
&&
2368 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
2369 goto bad_fork_cleanup_count
;
2371 current
->flags
&= ~PF_NPROC_EXCEEDED
;
2374 * If multiple threads are within copy_process(), then this check
2375 * triggers too late. This doesn't hurt, the check is only there
2376 * to stop root fork bombs.
2379 if (data_race(nr_threads
>= max_threads
))
2380 goto bad_fork_cleanup_count
;
2382 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
2383 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
| PF_NO_SETAFFINITY
);
2384 p
->flags
|= PF_FORKNOEXEC
;
2385 INIT_LIST_HEAD(&p
->children
);
2386 INIT_LIST_HEAD(&p
->sibling
);
2387 rcu_copy_process(p
);
2388 p
->vfork_done
= NULL
;
2389 spin_lock_init(&p
->alloc_lock
);
2391 init_sigpending(&p
->pending
);
2393 p
->utime
= p
->stime
= p
->gtime
= 0;
2394 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2395 p
->utimescaled
= p
->stimescaled
= 0;
2397 prev_cputime_init(&p
->prev_cputime
);
2399 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2400 seqcount_init(&p
->vtime
.seqcount
);
2401 p
->vtime
.starttime
= 0;
2402 p
->vtime
.state
= VTIME_INACTIVE
;
2405 #ifdef CONFIG_IO_URING
2409 #if defined(SPLIT_RSS_COUNTING)
2410 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
2413 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
2419 task_io_accounting_init(&p
->ioac
);
2420 acct_clear_integrals(p
);
2422 posix_cputimers_init(&p
->posix_cputimers
);
2424 p
->io_context
= NULL
;
2425 audit_set_context(p
, NULL
);
2427 if (args
->kthread
) {
2428 if (!set_kthread_struct(p
))
2429 goto bad_fork_cleanup_delayacct
;
2432 p
->mempolicy
= mpol_dup(p
->mempolicy
);
2433 if (IS_ERR(p
->mempolicy
)) {
2434 retval
= PTR_ERR(p
->mempolicy
);
2435 p
->mempolicy
= NULL
;
2436 goto bad_fork_cleanup_delayacct
;
2439 #ifdef CONFIG_CPUSETS
2440 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
2441 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
2442 seqcount_spinlock_init(&p
->mems_allowed_seq
, &p
->alloc_lock
);
2444 #ifdef CONFIG_TRACE_IRQFLAGS
2445 memset(&p
->irqtrace
, 0, sizeof(p
->irqtrace
));
2446 p
->irqtrace
.hardirq_disable_ip
= _THIS_IP_
;
2447 p
->irqtrace
.softirq_enable_ip
= _THIS_IP_
;
2448 p
->softirqs_enabled
= 1;
2449 p
->softirq_context
= 0;
2452 p
->pagefault_disabled
= 0;
2454 #ifdef CONFIG_LOCKDEP
2455 lockdep_init_task(p
);
2458 #ifdef CONFIG_DEBUG_MUTEXES
2459 p
->blocked_on
= NULL
; /* not blocked yet */
2461 #ifdef CONFIG_BCACHE
2462 p
->sequential_io
= 0;
2463 p
->sequential_io_avg
= 0;
2465 #ifdef CONFIG_BPF_SYSCALL
2466 RCU_INIT_POINTER(p
->bpf_storage
, NULL
);
2470 /* Perform scheduler related setup. Assign this task to a CPU. */
2471 retval
= sched_fork(clone_flags
, p
);
2473 goto bad_fork_cleanup_policy
;
2475 retval
= perf_event_init_task(p
, clone_flags
);
2477 goto bad_fork_cleanup_policy
;
2478 retval
= audit_alloc(p
);
2480 goto bad_fork_cleanup_perf
;
2481 /* copy all the process information */
2483 retval
= security_task_alloc(p
, clone_flags
);
2485 goto bad_fork_cleanup_audit
;
2486 retval
= copy_semundo(clone_flags
, p
);
2488 goto bad_fork_cleanup_security
;
2489 retval
= copy_files(clone_flags
, p
, args
->no_files
);
2491 goto bad_fork_cleanup_semundo
;
2492 retval
= copy_fs(clone_flags
, p
);
2494 goto bad_fork_cleanup_files
;
2495 retval
= copy_sighand(clone_flags
, p
);
2497 goto bad_fork_cleanup_fs
;
2498 retval
= copy_signal(clone_flags
, p
);
2500 goto bad_fork_cleanup_sighand
;
2501 retval
= copy_mm(clone_flags
, p
);
2503 goto bad_fork_cleanup_signal
;
2504 retval
= copy_namespaces(clone_flags
, p
);
2506 goto bad_fork_cleanup_mm
;
2507 retval
= copy_io(clone_flags
, p
);
2509 goto bad_fork_cleanup_namespaces
;
2510 retval
= copy_thread(p
, args
);
2512 goto bad_fork_cleanup_io
;
2514 stackleak_task_init(p
);
2516 if (pid
!= &init_struct_pid
) {
2517 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
, args
->set_tid
,
2518 args
->set_tid_size
);
2520 retval
= PTR_ERR(pid
);
2521 goto bad_fork_cleanup_thread
;
2526 * This has to happen after we've potentially unshared the file
2527 * descriptor table (so that the pidfd doesn't leak into the child
2528 * if the fd table isn't shared).
2530 if (clone_flags
& CLONE_PIDFD
) {
2531 /* Note that no task has been attached to @pid yet. */
2532 retval
= __pidfd_prepare(pid
, O_RDWR
| O_CLOEXEC
, &pidfile
);
2534 goto bad_fork_free_pid
;
2537 retval
= put_user(pidfd
, args
->pidfd
);
2539 goto bad_fork_put_pidfd
;
2548 * sigaltstack should be cleared when sharing the same VM
2550 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
2554 * Syscall tracing and stepping should be turned off in the
2555 * child regardless of CLONE_PTRACE.
2557 user_disable_single_step(p
);
2558 clear_task_syscall_work(p
, SYSCALL_TRACE
);
2559 #if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2560 clear_task_syscall_work(p
, SYSCALL_EMU
);
2562 clear_tsk_latency_tracing(p
);
2564 /* ok, now we should be set up.. */
2565 p
->pid
= pid_nr(pid
);
2566 if (clone_flags
& CLONE_THREAD
) {
2567 p
->group_leader
= current
->group_leader
;
2568 p
->tgid
= current
->tgid
;
2570 p
->group_leader
= p
;
2575 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2576 p
->dirty_paused_when
= 0;
2578 p
->pdeath_signal
= 0;
2579 INIT_LIST_HEAD(&p
->thread_group
);
2580 p
->task_works
= NULL
;
2581 clear_posix_cputimers_work(p
);
2583 #ifdef CONFIG_KRETPROBES
2584 p
->kretprobe_instances
.first
= NULL
;
2586 #ifdef CONFIG_RETHOOK
2587 p
->rethooks
.first
= NULL
;
2591 * Ensure that the cgroup subsystem policies allow the new process to be
2592 * forked. It should be noted that the new process's css_set can be changed
2593 * between here and cgroup_post_fork() if an organisation operation is in
2596 retval
= cgroup_can_fork(p
, args
);
2598 goto bad_fork_put_pidfd
;
2601 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2602 * the new task on the correct runqueue. All this *before* the task
2605 * This isn't part of ->can_fork() because while the re-cloning is
2606 * cgroup specific, it unconditionally needs to place the task on a
2609 sched_cgroup_fork(p
, args
);
2612 * From this point on we must avoid any synchronous user-space
2613 * communication until we take the tasklist-lock. In particular, we do
2614 * not want user-space to be able to predict the process start-time by
2615 * stalling fork(2) after we recorded the start_time but before it is
2616 * visible to the system.
2619 p
->start_time
= ktime_get_ns();
2620 p
->start_boottime
= ktime_get_boottime_ns();
2623 * Make it visible to the rest of the system, but dont wake it up yet.
2624 * Need tasklist lock for parent etc handling!
2626 write_lock_irq(&tasklist_lock
);
2628 /* CLONE_PARENT re-uses the old parent */
2629 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2630 p
->real_parent
= current
->real_parent
;
2631 p
->parent_exec_id
= current
->parent_exec_id
;
2632 if (clone_flags
& CLONE_THREAD
)
2633 p
->exit_signal
= -1;
2635 p
->exit_signal
= current
->group_leader
->exit_signal
;
2637 p
->real_parent
= current
;
2638 p
->parent_exec_id
= current
->self_exec_id
;
2639 p
->exit_signal
= args
->exit_signal
;
2642 klp_copy_process(p
);
2646 spin_lock(¤t
->sighand
->siglock
);
2650 rseq_fork(p
, clone_flags
);
2652 /* Don't start children in a dying pid namespace */
2653 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2655 goto bad_fork_cancel_cgroup
;
2658 /* Let kill terminate clone/fork in the middle */
2659 if (fatal_signal_pending(current
)) {
2661 goto bad_fork_cancel_cgroup
;
2664 /* No more failure paths after this point. */
2667 * Copy seccomp details explicitly here, in case they were changed
2668 * before holding sighand lock.
2672 init_task_pid_links(p
);
2673 if (likely(p
->pid
)) {
2674 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2676 init_task_pid(p
, PIDTYPE_PID
, pid
);
2677 if (thread_group_leader(p
)) {
2678 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2679 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2680 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2682 if (is_child_reaper(pid
)) {
2683 ns_of_pid(pid
)->child_reaper
= p
;
2684 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2686 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2687 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2689 * Inherit has_child_subreaper flag under the same
2690 * tasklist_lock with adding child to the process tree
2691 * for propagate_has_child_subreaper optimization.
2693 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2694 p
->real_parent
->signal
->is_child_subreaper
;
2695 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2696 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2697 attach_pid(p
, PIDTYPE_TGID
);
2698 attach_pid(p
, PIDTYPE_PGID
);
2699 attach_pid(p
, PIDTYPE_SID
);
2700 __this_cpu_inc(process_counts
);
2702 current
->signal
->nr_threads
++;
2703 current
->signal
->quick_threads
++;
2704 atomic_inc(¤t
->signal
->live
);
2705 refcount_inc(¤t
->signal
->sigcnt
);
2706 task_join_group_stop(p
);
2707 list_add_tail_rcu(&p
->thread_group
,
2708 &p
->group_leader
->thread_group
);
2709 list_add_tail_rcu(&p
->thread_node
,
2710 &p
->signal
->thread_head
);
2712 attach_pid(p
, PIDTYPE_PID
);
2716 hlist_del_init(&delayed
.node
);
2717 spin_unlock(¤t
->sighand
->siglock
);
2718 syscall_tracepoint_update(p
);
2719 write_unlock_irq(&tasklist_lock
);
2722 fd_install(pidfd
, pidfile
);
2724 proc_fork_connector(p
);
2726 cgroup_post_fork(p
, args
);
2729 trace_task_newtask(p
, clone_flags
);
2730 uprobe_copy_process(p
, clone_flags
);
2731 user_events_fork(p
, clone_flags
);
2733 copy_oom_score_adj(clone_flags
, p
);
2737 bad_fork_cancel_cgroup
:
2739 spin_unlock(¤t
->sighand
->siglock
);
2740 write_unlock_irq(&tasklist_lock
);
2741 cgroup_cancel_fork(p
, args
);
2743 if (clone_flags
& CLONE_PIDFD
) {
2745 put_unused_fd(pidfd
);
2748 if (pid
!= &init_struct_pid
)
2750 bad_fork_cleanup_thread
:
2752 bad_fork_cleanup_io
:
2755 bad_fork_cleanup_namespaces
:
2756 exit_task_namespaces(p
);
2757 bad_fork_cleanup_mm
:
2759 mm_clear_owner(p
->mm
, p
);
2762 bad_fork_cleanup_signal
:
2763 if (!(clone_flags
& CLONE_THREAD
))
2764 free_signal_struct(p
->signal
);
2765 bad_fork_cleanup_sighand
:
2766 __cleanup_sighand(p
->sighand
);
2767 bad_fork_cleanup_fs
:
2768 exit_fs(p
); /* blocking */
2769 bad_fork_cleanup_files
:
2770 exit_files(p
); /* blocking */
2771 bad_fork_cleanup_semundo
:
2773 bad_fork_cleanup_security
:
2774 security_task_free(p
);
2775 bad_fork_cleanup_audit
:
2777 bad_fork_cleanup_perf
:
2778 perf_event_free_task(p
);
2779 bad_fork_cleanup_policy
:
2780 lockdep_free_task(p
);
2782 mpol_put(p
->mempolicy
);
2784 bad_fork_cleanup_delayacct
:
2785 delayacct_tsk_free(p
);
2786 bad_fork_cleanup_count
:
2787 dec_rlimit_ucounts(task_ucounts(p
), UCOUNT_RLIMIT_NPROC
, 1);
2790 WRITE_ONCE(p
->__state
, TASK_DEAD
);
2791 exit_task_stack_account(p
);
2793 delayed_free_task(p
);
2795 spin_lock_irq(¤t
->sighand
->siglock
);
2796 hlist_del_init(&delayed
.node
);
2797 spin_unlock_irq(¤t
->sighand
->siglock
);
2798 return ERR_PTR(retval
);
2801 static inline void init_idle_pids(struct task_struct
*idle
)
2805 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2806 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2807 init_task_pid(idle
, type
, &init_struct_pid
);
2811 static int idle_dummy(void *dummy
)
2813 /* This function is never called */
2817 struct task_struct
* __init
fork_idle(int cpu
)
2819 struct task_struct
*task
;
2820 struct kernel_clone_args args
= {
2828 task
= copy_process(&init_struct_pid
, 0, cpu_to_node(cpu
), &args
);
2829 if (!IS_ERR(task
)) {
2830 init_idle_pids(task
);
2831 init_idle(task
, cpu
);
2838 * This is like kernel_clone(), but shaved down and tailored to just
2839 * creating io_uring workers. It returns a created task, or an error pointer.
2840 * The returned task is inactive, and the caller must fire it up through
2841 * wake_up_new_task(p). All signals are blocked in the created task.
2843 struct task_struct
*create_io_thread(int (*fn
)(void *), void *arg
, int node
)
2845 unsigned long flags
= CLONE_FS
|CLONE_FILES
|CLONE_SIGHAND
|CLONE_THREAD
|
2847 struct kernel_clone_args args
= {
2848 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2849 CLONE_UNTRACED
) & ~CSIGNAL
),
2850 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2857 return copy_process(NULL
, 0, node
, &args
);
2861 * Ok, this is the main fork-routine.
2863 * It copies the process, and if successful kick-starts
2864 * it and waits for it to finish using the VM if required.
2866 * args->exit_signal is expected to be checked for sanity by the caller.
2868 pid_t
kernel_clone(struct kernel_clone_args
*args
)
2870 u64 clone_flags
= args
->flags
;
2871 struct completion vfork
;
2873 struct task_struct
*p
;
2878 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2879 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2880 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2881 * field in struct clone_args and it still doesn't make sense to have
2882 * them both point at the same memory location. Performing this check
2883 * here has the advantage that we don't need to have a separate helper
2884 * to check for legacy clone().
2886 if ((args
->flags
& CLONE_PIDFD
) &&
2887 (args
->flags
& CLONE_PARENT_SETTID
) &&
2888 (args
->pidfd
== args
->parent_tid
))
2892 * Determine whether and which event to report to ptracer. When
2893 * called from kernel_thread or CLONE_UNTRACED is explicitly
2894 * requested, no event is reported; otherwise, report if the event
2895 * for the type of forking is enabled.
2897 if (!(clone_flags
& CLONE_UNTRACED
)) {
2898 if (clone_flags
& CLONE_VFORK
)
2899 trace
= PTRACE_EVENT_VFORK
;
2900 else if (args
->exit_signal
!= SIGCHLD
)
2901 trace
= PTRACE_EVENT_CLONE
;
2903 trace
= PTRACE_EVENT_FORK
;
2905 if (likely(!ptrace_event_enabled(current
, trace
)))
2909 p
= copy_process(NULL
, trace
, NUMA_NO_NODE
, args
);
2910 add_latent_entropy();
2916 * Do this prior waking up the new thread - the thread pointer
2917 * might get invalid after that point, if the thread exits quickly.
2919 trace_sched_process_fork(current
, p
);
2921 pid
= get_task_pid(p
, PIDTYPE_PID
);
2924 if (clone_flags
& CLONE_PARENT_SETTID
)
2925 put_user(nr
, args
->parent_tid
);
2927 if (clone_flags
& CLONE_VFORK
) {
2928 p
->vfork_done
= &vfork
;
2929 init_completion(&vfork
);
2933 if (IS_ENABLED(CONFIG_LRU_GEN
) && !(clone_flags
& CLONE_VM
)) {
2934 /* lock the task to synchronize with memcg migration */
2936 lru_gen_add_mm(p
->mm
);
2940 wake_up_new_task(p
);
2942 /* forking complete and child started to run, tell ptracer */
2943 if (unlikely(trace
))
2944 ptrace_event_pid(trace
, pid
);
2946 if (clone_flags
& CLONE_VFORK
) {
2947 if (!wait_for_vfork_done(p
, &vfork
))
2948 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2956 * Create a kernel thread.
2958 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, const char *name
,
2959 unsigned long flags
)
2961 struct kernel_clone_args args
= {
2962 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2963 CLONE_UNTRACED
) & ~CSIGNAL
),
2964 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2971 return kernel_clone(&args
);
2975 * Create a user mode thread.
2977 pid_t
user_mode_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2979 struct kernel_clone_args args
= {
2980 .flags
= ((lower_32_bits(flags
) | CLONE_VM
|
2981 CLONE_UNTRACED
) & ~CSIGNAL
),
2982 .exit_signal
= (lower_32_bits(flags
) & CSIGNAL
),
2987 return kernel_clone(&args
);
2990 #ifdef __ARCH_WANT_SYS_FORK
2991 SYSCALL_DEFINE0(fork
)
2994 struct kernel_clone_args args
= {
2995 .exit_signal
= SIGCHLD
,
2998 return kernel_clone(&args
);
3000 /* can not support in nommu mode */
3006 #ifdef __ARCH_WANT_SYS_VFORK
3007 SYSCALL_DEFINE0(vfork
)
3009 struct kernel_clone_args args
= {
3010 .flags
= CLONE_VFORK
| CLONE_VM
,
3011 .exit_signal
= SIGCHLD
,
3014 return kernel_clone(&args
);
3018 #ifdef __ARCH_WANT_SYS_CLONE
3019 #ifdef CONFIG_CLONE_BACKWARDS
3020 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
3021 int __user
*, parent_tidptr
,
3023 int __user
*, child_tidptr
)
3024 #elif defined(CONFIG_CLONE_BACKWARDS2)
3025 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
3026 int __user
*, parent_tidptr
,
3027 int __user
*, child_tidptr
,
3029 #elif defined(CONFIG_CLONE_BACKWARDS3)
3030 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
3032 int __user
*, parent_tidptr
,
3033 int __user
*, child_tidptr
,
3036 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
3037 int __user
*, parent_tidptr
,
3038 int __user
*, child_tidptr
,
3042 struct kernel_clone_args args
= {
3043 .flags
= (lower_32_bits(clone_flags
) & ~CSIGNAL
),
3044 .pidfd
= parent_tidptr
,
3045 .child_tid
= child_tidptr
,
3046 .parent_tid
= parent_tidptr
,
3047 .exit_signal
= (lower_32_bits(clone_flags
) & CSIGNAL
),
3052 return kernel_clone(&args
);
3056 #ifdef __ARCH_WANT_SYS_CLONE3
3058 noinline
static int copy_clone_args_from_user(struct kernel_clone_args
*kargs
,
3059 struct clone_args __user
*uargs
,
3063 struct clone_args args
;
3064 pid_t
*kset_tid
= kargs
->set_tid
;
3066 BUILD_BUG_ON(offsetofend(struct clone_args
, tls
) !=
3067 CLONE_ARGS_SIZE_VER0
);
3068 BUILD_BUG_ON(offsetofend(struct clone_args
, set_tid_size
) !=
3069 CLONE_ARGS_SIZE_VER1
);
3070 BUILD_BUG_ON(offsetofend(struct clone_args
, cgroup
) !=
3071 CLONE_ARGS_SIZE_VER2
);
3072 BUILD_BUG_ON(sizeof(struct clone_args
) != CLONE_ARGS_SIZE_VER2
);
3074 if (unlikely(usize
> PAGE_SIZE
))
3076 if (unlikely(usize
< CLONE_ARGS_SIZE_VER0
))
3079 err
= copy_struct_from_user(&args
, sizeof(args
), uargs
, usize
);
3083 if (unlikely(args
.set_tid_size
> MAX_PID_NS_LEVEL
))
3086 if (unlikely(!args
.set_tid
&& args
.set_tid_size
> 0))
3089 if (unlikely(args
.set_tid
&& args
.set_tid_size
== 0))
3093 * Verify that higher 32bits of exit_signal are unset and that
3094 * it is a valid signal
3096 if (unlikely((args
.exit_signal
& ~((u64
)CSIGNAL
)) ||
3097 !valid_signal(args
.exit_signal
)))
3100 if ((args
.flags
& CLONE_INTO_CGROUP
) &&
3101 (args
.cgroup
> INT_MAX
|| usize
< CLONE_ARGS_SIZE_VER2
))
3104 *kargs
= (struct kernel_clone_args
){
3105 .flags
= args
.flags
,
3106 .pidfd
= u64_to_user_ptr(args
.pidfd
),
3107 .child_tid
= u64_to_user_ptr(args
.child_tid
),
3108 .parent_tid
= u64_to_user_ptr(args
.parent_tid
),
3109 .exit_signal
= args
.exit_signal
,
3110 .stack
= args
.stack
,
3111 .stack_size
= args
.stack_size
,
3113 .set_tid_size
= args
.set_tid_size
,
3114 .cgroup
= args
.cgroup
,
3118 copy_from_user(kset_tid
, u64_to_user_ptr(args
.set_tid
),
3119 (kargs
->set_tid_size
* sizeof(pid_t
))))
3122 kargs
->set_tid
= kset_tid
;
3128 * clone3_stack_valid - check and prepare stack
3129 * @kargs: kernel clone args
3131 * Verify that the stack arguments userspace gave us are sane.
3132 * In addition, set the stack direction for userspace since it's easy for us to
3135 static inline bool clone3_stack_valid(struct kernel_clone_args
*kargs
)
3137 if (kargs
->stack
== 0) {
3138 if (kargs
->stack_size
> 0)
3141 if (kargs
->stack_size
== 0)
3144 if (!access_ok((void __user
*)kargs
->stack
, kargs
->stack_size
))
3147 #if !defined(CONFIG_STACK_GROWSUP) && !defined(CONFIG_IA64)
3148 kargs
->stack
+= kargs
->stack_size
;
3155 static bool clone3_args_valid(struct kernel_clone_args
*kargs
)
3157 /* Verify that no unknown flags are passed along. */
3159 ~(CLONE_LEGACY_FLAGS
| CLONE_CLEAR_SIGHAND
| CLONE_INTO_CGROUP
))
3163 * - make the CLONE_DETACHED bit reusable for clone3
3164 * - make the CSIGNAL bits reusable for clone3
3166 if (kargs
->flags
& (CLONE_DETACHED
| (CSIGNAL
& (~CLONE_NEWTIME
))))
3169 if ((kargs
->flags
& (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
)) ==
3170 (CLONE_SIGHAND
| CLONE_CLEAR_SIGHAND
))
3173 if ((kargs
->flags
& (CLONE_THREAD
| CLONE_PARENT
)) &&
3177 if (!clone3_stack_valid(kargs
))
3184 * clone3 - create a new process with specific properties
3185 * @uargs: argument structure
3186 * @size: size of @uargs
3188 * clone3() is the extensible successor to clone()/clone2().
3189 * It takes a struct as argument that is versioned by its size.
3191 * Return: On success, a positive PID for the child process.
3192 * On error, a negative errno number.
3194 SYSCALL_DEFINE2(clone3
, struct clone_args __user
*, uargs
, size_t, size
)
3198 struct kernel_clone_args kargs
;
3199 pid_t set_tid
[MAX_PID_NS_LEVEL
];
3201 kargs
.set_tid
= set_tid
;
3203 err
= copy_clone_args_from_user(&kargs
, uargs
, size
);
3207 if (!clone3_args_valid(&kargs
))
3210 return kernel_clone(&kargs
);
3214 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
3216 struct task_struct
*leader
, *parent
, *child
;
3219 read_lock(&tasklist_lock
);
3220 leader
= top
= top
->group_leader
;
3222 for_each_thread(leader
, parent
) {
3223 list_for_each_entry(child
, &parent
->children
, sibling
) {
3224 res
= visitor(child
, data
);
3236 if (leader
!= top
) {
3238 parent
= child
->real_parent
;
3239 leader
= parent
->group_leader
;
3243 read_unlock(&tasklist_lock
);
3246 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
3247 #define ARCH_MIN_MMSTRUCT_ALIGN 0
3250 static void sighand_ctor(void *data
)
3252 struct sighand_struct
*sighand
= data
;
3254 spin_lock_init(&sighand
->siglock
);
3255 init_waitqueue_head(&sighand
->signalfd_wqh
);
3258 void __init
mm_cache_init(void)
3260 unsigned int mm_size
;
3263 * The mm_cpumask is located at the end of mm_struct, and is
3264 * dynamically sized based on the maximum CPU number this system
3265 * can have, taking hotplug into account (nr_cpu_ids).
3267 mm_size
= sizeof(struct mm_struct
) + cpumask_size() + mm_cid_size();
3269 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
3270 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
3271 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3272 offsetof(struct mm_struct
, saved_auxv
),
3273 sizeof_field(struct mm_struct
, saved_auxv
),
3277 void __init
proc_caches_init(void)
3279 sighand_cachep
= kmem_cache_create("sighand_cache",
3280 sizeof(struct sighand_struct
), 0,
3281 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
3282 SLAB_ACCOUNT
, sighand_ctor
);
3283 signal_cachep
= kmem_cache_create("signal_cache",
3284 sizeof(struct signal_struct
), 0,
3285 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3287 files_cachep
= kmem_cache_create("files_cache",
3288 sizeof(struct files_struct
), 0,
3289 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3291 fs_cachep
= kmem_cache_create("fs_cache",
3292 sizeof(struct fs_struct
), 0,
3293 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
3296 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
3297 #ifdef CONFIG_PER_VMA_LOCK
3298 vma_lock_cachep
= KMEM_CACHE(vma_lock
, SLAB_PANIC
|SLAB_ACCOUNT
);
3301 nsproxy_cache_init();
3305 * Check constraints on flags passed to the unshare system call.
3307 static int check_unshare_flags(unsigned long unshare_flags
)
3309 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
3310 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
3311 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
3312 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
|
3316 * Not implemented, but pretend it works if there is nothing
3317 * to unshare. Note that unsharing the address space or the
3318 * signal handlers also need to unshare the signal queues (aka
3321 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
3322 if (!thread_group_empty(current
))
3325 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
3326 if (refcount_read(¤t
->sighand
->count
) > 1)
3329 if (unshare_flags
& CLONE_VM
) {
3330 if (!current_is_single_threaded())
3338 * Unshare the filesystem structure if it is being shared
3340 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
3342 struct fs_struct
*fs
= current
->fs
;
3344 if (!(unshare_flags
& CLONE_FS
) || !fs
)
3347 /* don't need lock here; in the worst case we'll do useless copy */
3351 *new_fsp
= copy_fs_struct(fs
);
3359 * Unshare file descriptor table if it is being shared
3361 int unshare_fd(unsigned long unshare_flags
, unsigned int max_fds
,
3362 struct files_struct
**new_fdp
)
3364 struct files_struct
*fd
= current
->files
;
3367 if ((unshare_flags
& CLONE_FILES
) &&
3368 (fd
&& atomic_read(&fd
->count
) > 1)) {
3369 *new_fdp
= dup_fd(fd
, max_fds
, &error
);
3378 * unshare allows a process to 'unshare' part of the process
3379 * context which was originally shared using clone. copy_*
3380 * functions used by kernel_clone() cannot be used here directly
3381 * because they modify an inactive task_struct that is being
3382 * constructed. Here we are modifying the current, active,
3385 int ksys_unshare(unsigned long unshare_flags
)
3387 struct fs_struct
*fs
, *new_fs
= NULL
;
3388 struct files_struct
*new_fd
= NULL
;
3389 struct cred
*new_cred
= NULL
;
3390 struct nsproxy
*new_nsproxy
= NULL
;
3395 * If unsharing a user namespace must also unshare the thread group
3396 * and unshare the filesystem root and working directories.
3398 if (unshare_flags
& CLONE_NEWUSER
)
3399 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
3401 * If unsharing vm, must also unshare signal handlers.
3403 if (unshare_flags
& CLONE_VM
)
3404 unshare_flags
|= CLONE_SIGHAND
;
3406 * If unsharing a signal handlers, must also unshare the signal queues.
3408 if (unshare_flags
& CLONE_SIGHAND
)
3409 unshare_flags
|= CLONE_THREAD
;
3411 * If unsharing namespace, must also unshare filesystem information.
3413 if (unshare_flags
& CLONE_NEWNS
)
3414 unshare_flags
|= CLONE_FS
;
3416 err
= check_unshare_flags(unshare_flags
);
3418 goto bad_unshare_out
;
3420 * CLONE_NEWIPC must also detach from the undolist: after switching
3421 * to a new ipc namespace, the semaphore arrays from the old
3422 * namespace are unreachable.
3424 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
3426 err
= unshare_fs(unshare_flags
, &new_fs
);
3428 goto bad_unshare_out
;
3429 err
= unshare_fd(unshare_flags
, NR_OPEN_MAX
, &new_fd
);
3431 goto bad_unshare_cleanup_fs
;
3432 err
= unshare_userns(unshare_flags
, &new_cred
);
3434 goto bad_unshare_cleanup_fd
;
3435 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
3438 goto bad_unshare_cleanup_cred
;
3441 err
= set_cred_ucounts(new_cred
);
3443 goto bad_unshare_cleanup_cred
;
3446 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
3449 * CLONE_SYSVSEM is equivalent to sys_exit().
3453 if (unshare_flags
& CLONE_NEWIPC
) {
3454 /* Orphan segments in old ns (see sem above). */
3456 shm_init_task(current
);
3460 switch_task_namespaces(current
, new_nsproxy
);
3466 spin_lock(&fs
->lock
);
3467 current
->fs
= new_fs
;
3472 spin_unlock(&fs
->lock
);
3476 swap(current
->files
, new_fd
);
3478 task_unlock(current
);
3481 /* Install the new user namespace */
3482 commit_creds(new_cred
);
3487 perf_event_namespaces(current
);
3489 bad_unshare_cleanup_cred
:
3492 bad_unshare_cleanup_fd
:
3494 put_files_struct(new_fd
);
3496 bad_unshare_cleanup_fs
:
3498 free_fs_struct(new_fs
);
3504 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
3506 return ksys_unshare(unshare_flags
);
3510 * Helper to unshare the files of the current task.
3511 * We don't want to expose copy_files internals to
3512 * the exec layer of the kernel.
3515 int unshare_files(void)
3517 struct task_struct
*task
= current
;
3518 struct files_struct
*old
, *copy
= NULL
;
3521 error
= unshare_fd(CLONE_FILES
, NR_OPEN_MAX
, ©
);
3529 put_files_struct(old
);
3533 int sysctl_max_threads(struct ctl_table
*table
, int write
,
3534 void *buffer
, size_t *lenp
, loff_t
*ppos
)
3538 int threads
= max_threads
;
3540 int max
= MAX_THREADS
;
3547 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
3551 max_threads
= threads
;