4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * 'fork.c' contains the help-routines for the 'fork' system call
9 * (see also entry.S and others).
10 * Fork is rather simple, once you get the hang of it, but the memory
11 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
14 #include <linux/slab.h>
15 #include <linux/sched/autogroup.h>
16 #include <linux/sched/mm.h>
17 #include <linux/sched/coredump.h>
18 #include <linux/sched/user.h>
19 #include <linux/sched/numa_balancing.h>
20 #include <linux/sched/stat.h>
21 #include <linux/sched/task.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/sched/cputime.h>
24 #include <linux/rtmutex.h>
25 #include <linux/init.h>
26 #include <linux/unistd.h>
27 #include <linux/module.h>
28 #include <linux/vmalloc.h>
29 #include <linux/completion.h>
30 #include <linux/personality.h>
31 #include <linux/mempolicy.h>
32 #include <linux/sem.h>
33 #include <linux/file.h>
34 #include <linux/fdtable.h>
35 #include <linux/iocontext.h>
36 #include <linux/key.h>
37 #include <linux/binfmts.h>
38 #include <linux/mman.h>
39 #include <linux/mmu_notifier.h>
40 #include <linux/hmm.h>
43 #include <linux/vmacache.h>
44 #include <linux/nsproxy.h>
45 #include <linux/capability.h>
46 #include <linux/cpu.h>
47 #include <linux/cgroup.h>
48 #include <linux/security.h>
49 #include <linux/hugetlb.h>
50 #include <linux/seccomp.h>
51 #include <linux/swap.h>
52 #include <linux/syscalls.h>
53 #include <linux/jiffies.h>
54 #include <linux/futex.h>
55 #include <linux/compat.h>
56 #include <linux/kthread.h>
57 #include <linux/task_io_accounting_ops.h>
58 #include <linux/rcupdate.h>
59 #include <linux/ptrace.h>
60 #include <linux/mount.h>
61 #include <linux/audit.h>
62 #include <linux/memcontrol.h>
63 #include <linux/ftrace.h>
64 #include <linux/proc_fs.h>
65 #include <linux/profile.h>
66 #include <linux/rmap.h>
67 #include <linux/ksm.h>
68 #include <linux/acct.h>
69 #include <linux/userfaultfd_k.h>
70 #include <linux/tsacct_kern.h>
71 #include <linux/cn_proc.h>
72 #include <linux/freezer.h>
73 #include <linux/delayacct.h>
74 #include <linux/taskstats_kern.h>
75 #include <linux/random.h>
76 #include <linux/tty.h>
77 #include <linux/blkdev.h>
78 #include <linux/fs_struct.h>
79 #include <linux/magic.h>
80 #include <linux/perf_event.h>
81 #include <linux/posix-timers.h>
82 #include <linux/user-return-notifier.h>
83 #include <linux/oom.h>
84 #include <linux/khugepaged.h>
85 #include <linux/signalfd.h>
86 #include <linux/uprobes.h>
87 #include <linux/aio.h>
88 #include <linux/compiler.h>
89 #include <linux/sysctl.h>
90 #include <linux/kcov.h>
91 #include <linux/livepatch.h>
92 #include <linux/thread_info.h>
93 #include <linux/stackleak.h>
95 #include <asm/pgtable.h>
96 #include <asm/pgalloc.h>
97 #include <linux/uaccess.h>
98 #include <asm/mmu_context.h>
99 #include <asm/cacheflush.h>
100 #include <asm/tlbflush.h>
102 #include <trace/events/sched.h>
104 #define CREATE_TRACE_POINTS
105 #include <trace/events/task.h>
108 * Minimum number of threads to boot the kernel
110 #define MIN_THREADS 20
113 * Maximum number of threads
115 #define MAX_THREADS FUTEX_TID_MASK
118 * Protected counters by write_lock_irq(&tasklist_lock)
120 unsigned long total_forks
; /* Handle normal Linux uptimes. */
121 int nr_threads
; /* The idle threads do not count.. */
123 int max_threads
; /* tunable limit on nr_threads */
125 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
127 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
129 #ifdef CONFIG_PROVE_RCU
130 int lockdep_tasklist_lock_is_held(void)
132 return lockdep_is_held(&tasklist_lock
);
134 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
135 #endif /* #ifdef CONFIG_PROVE_RCU */
137 int nr_processes(void)
142 for_each_possible_cpu(cpu
)
143 total
+= per_cpu(process_counts
, cpu
);
148 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
152 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
153 static struct kmem_cache
*task_struct_cachep
;
155 static inline struct task_struct
*alloc_task_struct_node(int node
)
157 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
160 static inline void free_task_struct(struct task_struct
*tsk
)
162 kmem_cache_free(task_struct_cachep
, tsk
);
166 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
169 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
170 * kmemcache based allocator.
172 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
174 #ifdef CONFIG_VMAP_STACK
176 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
177 * flush. Try to minimize the number of calls by caching stacks.
179 #define NR_CACHED_STACKS 2
180 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
182 static int free_vm_stack_cache(unsigned int cpu
)
184 struct vm_struct
**cached_vm_stacks
= per_cpu_ptr(cached_stacks
, cpu
);
187 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
188 struct vm_struct
*vm_stack
= cached_vm_stacks
[i
];
193 vfree(vm_stack
->addr
);
194 cached_vm_stacks
[i
] = NULL
;
201 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
203 #ifdef CONFIG_VMAP_STACK
207 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
210 s
= this_cpu_xchg(cached_stacks
[i
], NULL
);
215 /* Clear stale pointers from reused stack. */
216 memset(s
->addr
, 0, THREAD_SIZE
);
218 tsk
->stack_vm_area
= s
;
219 tsk
->stack
= s
->addr
;
224 * Allocated stacks are cached and later reused by new threads,
225 * so memcg accounting is performed manually on assigning/releasing
226 * stacks to tasks. Drop __GFP_ACCOUNT.
228 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_ALIGN
,
229 VMALLOC_START
, VMALLOC_END
,
230 THREADINFO_GFP
& ~__GFP_ACCOUNT
,
232 0, node
, __builtin_return_address(0));
235 * We can't call find_vm_area() in interrupt context, and
236 * free_thread_stack() can be called in interrupt context,
237 * so cache the vm_struct.
240 tsk
->stack_vm_area
= find_vm_area(stack
);
245 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
249 tsk
->stack
= page_address(page
);
256 static inline void free_thread_stack(struct task_struct
*tsk
)
258 #ifdef CONFIG_VMAP_STACK
259 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
264 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
265 mod_memcg_page_state(vm
->pages
[i
],
266 MEMCG_KERNEL_STACK_KB
,
267 -(int)(PAGE_SIZE
/ 1024));
269 memcg_kmem_uncharge(vm
->pages
[i
], 0);
272 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
273 if (this_cpu_cmpxchg(cached_stacks
[i
],
274 NULL
, tsk
->stack_vm_area
) != NULL
)
280 vfree_atomic(tsk
->stack
);
285 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
288 static struct kmem_cache
*thread_stack_cache
;
290 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
293 unsigned long *stack
;
294 stack
= kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
299 static void free_thread_stack(struct task_struct
*tsk
)
301 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
304 void thread_stack_cache_init(void)
306 thread_stack_cache
= kmem_cache_create_usercopy("thread_stack",
307 THREAD_SIZE
, THREAD_SIZE
, 0, 0,
309 BUG_ON(thread_stack_cache
== NULL
);
314 /* SLAB cache for signal_struct structures (tsk->signal) */
315 static struct kmem_cache
*signal_cachep
;
317 /* SLAB cache for sighand_struct structures (tsk->sighand) */
318 struct kmem_cache
*sighand_cachep
;
320 /* SLAB cache for files_struct structures (tsk->files) */
321 struct kmem_cache
*files_cachep
;
323 /* SLAB cache for fs_struct structures (tsk->fs) */
324 struct kmem_cache
*fs_cachep
;
326 /* SLAB cache for vm_area_struct structures */
327 static struct kmem_cache
*vm_area_cachep
;
329 /* SLAB cache for mm_struct structures (tsk->mm) */
330 static struct kmem_cache
*mm_cachep
;
332 struct vm_area_struct
*vm_area_alloc(struct mm_struct
*mm
)
334 struct vm_area_struct
*vma
;
336 vma
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
342 struct vm_area_struct
*vm_area_dup(struct vm_area_struct
*orig
)
344 struct vm_area_struct
*new = kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
348 INIT_LIST_HEAD(&new->anon_vma_chain
);
353 void vm_area_free(struct vm_area_struct
*vma
)
355 kmem_cache_free(vm_area_cachep
, vma
);
358 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
360 void *stack
= task_stack_page(tsk
);
361 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
363 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
368 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
370 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
371 mod_zone_page_state(page_zone(vm
->pages
[i
]),
373 PAGE_SIZE
/ 1024 * account
);
377 * All stack pages are in the same zone and belong to the
380 struct page
*first_page
= virt_to_page(stack
);
382 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
383 THREAD_SIZE
/ 1024 * account
);
385 mod_memcg_page_state(first_page
, MEMCG_KERNEL_STACK_KB
,
386 account
* (THREAD_SIZE
/ 1024));
390 static int memcg_charge_kernel_stack(struct task_struct
*tsk
)
392 #ifdef CONFIG_VMAP_STACK
393 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
399 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
401 * If memcg_kmem_charge() fails, page->mem_cgroup
402 * pointer is NULL, and both memcg_kmem_uncharge()
403 * and mod_memcg_page_state() in free_thread_stack()
404 * will ignore this page. So it's safe.
406 ret
= memcg_kmem_charge(vm
->pages
[i
], GFP_KERNEL
, 0);
410 mod_memcg_page_state(vm
->pages
[i
],
411 MEMCG_KERNEL_STACK_KB
,
419 static void release_task_stack(struct task_struct
*tsk
)
421 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
422 return; /* Better to leak the stack than to free prematurely */
424 account_kernel_stack(tsk
, -1);
425 free_thread_stack(tsk
);
427 #ifdef CONFIG_VMAP_STACK
428 tsk
->stack_vm_area
= NULL
;
432 #ifdef CONFIG_THREAD_INFO_IN_TASK
433 void put_task_stack(struct task_struct
*tsk
)
435 if (refcount_dec_and_test(&tsk
->stack_refcount
))
436 release_task_stack(tsk
);
440 void free_task(struct task_struct
*tsk
)
442 #ifndef CONFIG_THREAD_INFO_IN_TASK
444 * The task is finally done with both the stack and thread_info,
447 release_task_stack(tsk
);
450 * If the task had a separate stack allocation, it should be gone
453 WARN_ON_ONCE(refcount_read(&tsk
->stack_refcount
) != 0);
455 rt_mutex_debug_task_free(tsk
);
456 ftrace_graph_exit_task(tsk
);
457 put_seccomp_filter(tsk
);
458 arch_release_task_struct(tsk
);
459 if (tsk
->flags
& PF_KTHREAD
)
460 free_kthread_struct(tsk
);
461 free_task_struct(tsk
);
463 EXPORT_SYMBOL(free_task
);
466 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
467 struct mm_struct
*oldmm
)
469 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
470 struct rb_node
**rb_link
, *rb_parent
;
472 unsigned long charge
;
475 uprobe_start_dup_mmap();
476 if (down_write_killable(&oldmm
->mmap_sem
)) {
478 goto fail_uprobe_end
;
480 flush_cache_dup_mm(oldmm
);
481 uprobe_dup_mmap(oldmm
, mm
);
483 * Not linked in yet - no deadlock potential:
485 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
487 /* No ordering required: file already has been exposed. */
488 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
490 mm
->total_vm
= oldmm
->total_vm
;
491 mm
->data_vm
= oldmm
->data_vm
;
492 mm
->exec_vm
= oldmm
->exec_vm
;
493 mm
->stack_vm
= oldmm
->stack_vm
;
495 rb_link
= &mm
->mm_rb
.rb_node
;
498 retval
= ksm_fork(mm
, oldmm
);
501 retval
= khugepaged_fork(mm
, oldmm
);
506 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
509 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
510 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
515 * Don't duplicate many vmas if we've been oom-killed (for
518 if (fatal_signal_pending(current
)) {
522 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
523 unsigned long len
= vma_pages(mpnt
);
525 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
529 tmp
= vm_area_dup(mpnt
);
532 retval
= vma_dup_policy(mpnt
, tmp
);
534 goto fail_nomem_policy
;
536 retval
= dup_userfaultfd(tmp
, &uf
);
538 goto fail_nomem_anon_vma_fork
;
539 if (tmp
->vm_flags
& VM_WIPEONFORK
) {
540 /* VM_WIPEONFORK gets a clean slate in the child. */
541 tmp
->anon_vma
= NULL
;
542 if (anon_vma_prepare(tmp
))
543 goto fail_nomem_anon_vma_fork
;
544 } else if (anon_vma_fork(tmp
, mpnt
))
545 goto fail_nomem_anon_vma_fork
;
546 tmp
->vm_flags
&= ~(VM_LOCKED
| VM_LOCKONFAULT
);
547 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
550 struct inode
*inode
= file_inode(file
);
551 struct address_space
*mapping
= file
->f_mapping
;
554 if (tmp
->vm_flags
& VM_DENYWRITE
)
555 atomic_dec(&inode
->i_writecount
);
556 i_mmap_lock_write(mapping
);
557 if (tmp
->vm_flags
& VM_SHARED
)
558 atomic_inc(&mapping
->i_mmap_writable
);
559 flush_dcache_mmap_lock(mapping
);
560 /* insert tmp into the share list, just after mpnt */
561 vma_interval_tree_insert_after(tmp
, mpnt
,
563 flush_dcache_mmap_unlock(mapping
);
564 i_mmap_unlock_write(mapping
);
568 * Clear hugetlb-related page reserves for children. This only
569 * affects MAP_PRIVATE mappings. Faults generated by the child
570 * are not guaranteed to succeed, even if read-only
572 if (is_vm_hugetlb_page(tmp
))
573 reset_vma_resv_huge_pages(tmp
);
576 * Link in the new vma and copy the page table entries.
579 pprev
= &tmp
->vm_next
;
583 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
584 rb_link
= &tmp
->vm_rb
.rb_right
;
585 rb_parent
= &tmp
->vm_rb
;
588 if (!(tmp
->vm_flags
& VM_WIPEONFORK
))
589 retval
= copy_page_range(mm
, oldmm
, mpnt
);
591 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
592 tmp
->vm_ops
->open(tmp
);
597 /* a new mm has just been created */
598 retval
= arch_dup_mmap(oldmm
, mm
);
600 up_write(&mm
->mmap_sem
);
602 up_write(&oldmm
->mmap_sem
);
603 dup_userfaultfd_complete(&uf
);
605 uprobe_end_dup_mmap();
607 fail_nomem_anon_vma_fork
:
608 mpol_put(vma_policy(tmp
));
613 vm_unacct_memory(charge
);
617 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
619 mm
->pgd
= pgd_alloc(mm
);
620 if (unlikely(!mm
->pgd
))
625 static inline void mm_free_pgd(struct mm_struct
*mm
)
627 pgd_free(mm
, mm
->pgd
);
630 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
632 down_write(&oldmm
->mmap_sem
);
633 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
634 up_write(&oldmm
->mmap_sem
);
637 #define mm_alloc_pgd(mm) (0)
638 #define mm_free_pgd(mm)
639 #endif /* CONFIG_MMU */
641 static void check_mm(struct mm_struct
*mm
)
645 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
646 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
649 printk(KERN_ALERT
"BUG: Bad rss-counter state "
650 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
653 if (mm_pgtables_bytes(mm
))
654 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
655 mm_pgtables_bytes(mm
));
657 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
658 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
662 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
663 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
666 * Called when the last reference to the mm
667 * is dropped: either by a lazy thread or by
668 * mmput. Free the page directory and the mm.
670 void __mmdrop(struct mm_struct
*mm
)
672 BUG_ON(mm
== &init_mm
);
673 WARN_ON_ONCE(mm
== current
->mm
);
674 WARN_ON_ONCE(mm
== current
->active_mm
);
678 mmu_notifier_mm_destroy(mm
);
680 put_user_ns(mm
->user_ns
);
683 EXPORT_SYMBOL_GPL(__mmdrop
);
685 static void mmdrop_async_fn(struct work_struct
*work
)
687 struct mm_struct
*mm
;
689 mm
= container_of(work
, struct mm_struct
, async_put_work
);
693 static void mmdrop_async(struct mm_struct
*mm
)
695 if (unlikely(atomic_dec_and_test(&mm
->mm_count
))) {
696 INIT_WORK(&mm
->async_put_work
, mmdrop_async_fn
);
697 schedule_work(&mm
->async_put_work
);
701 static inline void free_signal_struct(struct signal_struct
*sig
)
703 taskstats_tgid_free(sig
);
704 sched_autogroup_exit(sig
);
706 * __mmdrop is not safe to call from softirq context on x86 due to
707 * pgd_dtor so postpone it to the async context
710 mmdrop_async(sig
->oom_mm
);
711 kmem_cache_free(signal_cachep
, sig
);
714 static inline void put_signal_struct(struct signal_struct
*sig
)
716 if (refcount_dec_and_test(&sig
->sigcnt
))
717 free_signal_struct(sig
);
720 void __put_task_struct(struct task_struct
*tsk
)
722 WARN_ON(!tsk
->exit_state
);
723 WARN_ON(refcount_read(&tsk
->usage
));
724 WARN_ON(tsk
== current
);
728 security_task_free(tsk
);
730 delayacct_tsk_free(tsk
);
731 put_signal_struct(tsk
->signal
);
733 if (!profile_handoff_task(tsk
))
736 EXPORT_SYMBOL_GPL(__put_task_struct
);
738 void __init __weak
arch_task_cache_init(void) { }
743 static void set_max_threads(unsigned int max_threads_suggested
)
746 unsigned long nr_pages
= totalram_pages();
749 * The number of threads shall be limited such that the thread
750 * structures may only consume a small part of the available memory.
752 if (fls64(nr_pages
) + fls64(PAGE_SIZE
) > 64)
753 threads
= MAX_THREADS
;
755 threads
= div64_u64((u64
) nr_pages
* (u64
) PAGE_SIZE
,
756 (u64
) THREAD_SIZE
* 8UL);
758 if (threads
> max_threads_suggested
)
759 threads
= max_threads_suggested
;
761 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
764 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
765 /* Initialized by the architecture: */
766 int arch_task_struct_size __read_mostly
;
769 static void task_struct_whitelist(unsigned long *offset
, unsigned long *size
)
771 /* Fetch thread_struct whitelist for the architecture. */
772 arch_thread_struct_whitelist(offset
, size
);
775 * Handle zero-sized whitelist or empty thread_struct, otherwise
776 * adjust offset to position of thread_struct in task_struct.
778 if (unlikely(*size
== 0))
781 *offset
+= offsetof(struct task_struct
, thread
);
784 void __init
fork_init(void)
787 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
788 #ifndef ARCH_MIN_TASKALIGN
789 #define ARCH_MIN_TASKALIGN 0
791 int align
= max_t(int, L1_CACHE_BYTES
, ARCH_MIN_TASKALIGN
);
792 unsigned long useroffset
, usersize
;
794 /* create a slab on which task_structs can be allocated */
795 task_struct_whitelist(&useroffset
, &usersize
);
796 task_struct_cachep
= kmem_cache_create_usercopy("task_struct",
797 arch_task_struct_size
, align
,
798 SLAB_PANIC
|SLAB_ACCOUNT
,
799 useroffset
, usersize
, NULL
);
802 /* do the arch specific task caches init */
803 arch_task_cache_init();
805 set_max_threads(MAX_THREADS
);
807 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
808 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
809 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
810 init_task
.signal
->rlim
[RLIMIT_NPROC
];
812 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
813 init_user_ns
.ucount_max
[i
] = max_threads
/2;
816 #ifdef CONFIG_VMAP_STACK
817 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN
, "fork:vm_stack_cache",
818 NULL
, free_vm_stack_cache
);
821 lockdep_init_task(&init_task
);
824 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
825 struct task_struct
*src
)
831 void set_task_stack_end_magic(struct task_struct
*tsk
)
833 unsigned long *stackend
;
835 stackend
= end_of_stack(tsk
);
836 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
839 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
841 struct task_struct
*tsk
;
842 unsigned long *stack
;
843 struct vm_struct
*stack_vm_area __maybe_unused
;
846 if (node
== NUMA_NO_NODE
)
847 node
= tsk_fork_get_node(orig
);
848 tsk
= alloc_task_struct_node(node
);
852 stack
= alloc_thread_stack_node(tsk
, node
);
856 if (memcg_charge_kernel_stack(tsk
))
859 stack_vm_area
= task_stack_vm_area(tsk
);
861 err
= arch_dup_task_struct(tsk
, orig
);
864 * arch_dup_task_struct() clobbers the stack-related fields. Make
865 * sure they're properly initialized before using any stack-related
869 #ifdef CONFIG_VMAP_STACK
870 tsk
->stack_vm_area
= stack_vm_area
;
872 #ifdef CONFIG_THREAD_INFO_IN_TASK
873 refcount_set(&tsk
->stack_refcount
, 1);
879 #ifdef CONFIG_SECCOMP
881 * We must handle setting up seccomp filters once we're under
882 * the sighand lock in case orig has changed between now and
883 * then. Until then, filter must be NULL to avoid messing up
884 * the usage counts on the error path calling free_task.
886 tsk
->seccomp
.filter
= NULL
;
889 setup_thread_stack(tsk
, orig
);
890 clear_user_return_notifier(tsk
);
891 clear_tsk_need_resched(tsk
);
892 set_task_stack_end_magic(tsk
);
894 #ifdef CONFIG_STACKPROTECTOR
895 tsk
->stack_canary
= get_random_canary();
899 * One for us, one for whoever does the "release_task()" (usually
902 refcount_set(&tsk
->usage
, 2);
903 #ifdef CONFIG_BLK_DEV_IO_TRACE
906 tsk
->splice_pipe
= NULL
;
907 tsk
->task_frag
.page
= NULL
;
908 tsk
->wake_q
.next
= NULL
;
910 account_kernel_stack(tsk
, 1);
914 #ifdef CONFIG_FAULT_INJECTION
918 #ifdef CONFIG_BLK_CGROUP
919 tsk
->throttle_queue
= NULL
;
920 tsk
->use_memdelay
= 0;
924 tsk
->active_memcg
= NULL
;
929 free_thread_stack(tsk
);
931 free_task_struct(tsk
);
935 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
937 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
939 static int __init
coredump_filter_setup(char *s
)
941 default_dump_filter
=
942 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
943 MMF_DUMP_FILTER_MASK
;
947 __setup("coredump_filter=", coredump_filter_setup
);
949 #include <linux/init_task.h>
951 static void mm_init_aio(struct mm_struct
*mm
)
954 spin_lock_init(&mm
->ioctx_lock
);
955 mm
->ioctx_table
= NULL
;
959 static __always_inline
void mm_clear_owner(struct mm_struct
*mm
,
960 struct task_struct
*p
)
964 WRITE_ONCE(mm
->owner
, NULL
);
968 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
975 static void mm_init_uprobes_state(struct mm_struct
*mm
)
977 #ifdef CONFIG_UPROBES
978 mm
->uprobes_state
.xol_area
= NULL
;
982 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
983 struct user_namespace
*user_ns
)
987 mm
->vmacache_seqnum
= 0;
988 atomic_set(&mm
->mm_users
, 1);
989 atomic_set(&mm
->mm_count
, 1);
990 init_rwsem(&mm
->mmap_sem
);
991 INIT_LIST_HEAD(&mm
->mmlist
);
992 mm
->core_state
= NULL
;
993 mm_pgtables_bytes_init(mm
);
996 atomic64_set(&mm
->pinned_vm
, 0);
997 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
998 spin_lock_init(&mm
->page_table_lock
);
999 spin_lock_init(&mm
->arg_lock
);
1000 mm_init_cpumask(mm
);
1002 mm_init_owner(mm
, p
);
1003 RCU_INIT_POINTER(mm
->exe_file
, NULL
);
1004 mmu_notifier_mm_init(mm
);
1006 init_tlb_flush_pending(mm
);
1007 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1008 mm
->pmd_huge_pte
= NULL
;
1010 mm_init_uprobes_state(mm
);
1013 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
1014 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
1016 mm
->flags
= default_dump_filter
;
1020 if (mm_alloc_pgd(mm
))
1023 if (init_new_context(p
, mm
))
1024 goto fail_nocontext
;
1026 mm
->user_ns
= get_user_ns(user_ns
);
1037 * Allocate and initialize an mm_struct.
1039 struct mm_struct
*mm_alloc(void)
1041 struct mm_struct
*mm
;
1047 memset(mm
, 0, sizeof(*mm
));
1048 return mm_init(mm
, current
, current_user_ns());
1051 static inline void __mmput(struct mm_struct
*mm
)
1053 VM_BUG_ON(atomic_read(&mm
->mm_users
));
1055 uprobe_clear_state(mm
);
1058 khugepaged_exit(mm
); /* must run before exit_mmap */
1060 mm_put_huge_zero_page(mm
);
1061 set_mm_exe_file(mm
, NULL
);
1062 if (!list_empty(&mm
->mmlist
)) {
1063 spin_lock(&mmlist_lock
);
1064 list_del(&mm
->mmlist
);
1065 spin_unlock(&mmlist_lock
);
1068 module_put(mm
->binfmt
->module
);
1073 * Decrement the use count and release all resources for an mm.
1075 void mmput(struct mm_struct
*mm
)
1079 if (atomic_dec_and_test(&mm
->mm_users
))
1082 EXPORT_SYMBOL_GPL(mmput
);
1085 static void mmput_async_fn(struct work_struct
*work
)
1087 struct mm_struct
*mm
= container_of(work
, struct mm_struct
,
1093 void mmput_async(struct mm_struct
*mm
)
1095 if (atomic_dec_and_test(&mm
->mm_users
)) {
1096 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
1097 schedule_work(&mm
->async_put_work
);
1103 * set_mm_exe_file - change a reference to the mm's executable file
1105 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1107 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1108 * invocations: in mmput() nobody alive left, in execve task is single
1109 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
1110 * mm->exe_file, but does so without using set_mm_exe_file() in order
1111 * to do avoid the need for any locks.
1113 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
1115 struct file
*old_exe_file
;
1118 * It is safe to dereference the exe_file without RCU as
1119 * this function is only called if nobody else can access
1120 * this mm -- see comment above for justification.
1122 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
1125 get_file(new_exe_file
);
1126 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
1132 * get_mm_exe_file - acquire a reference to the mm's executable file
1134 * Returns %NULL if mm has no associated executable file.
1135 * User must release file via fput().
1137 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
1139 struct file
*exe_file
;
1142 exe_file
= rcu_dereference(mm
->exe_file
);
1143 if (exe_file
&& !get_file_rcu(exe_file
))
1148 EXPORT_SYMBOL(get_mm_exe_file
);
1151 * get_task_exe_file - acquire a reference to the task's executable file
1153 * Returns %NULL if task's mm (if any) has no associated executable file or
1154 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1155 * User must release file via fput().
1157 struct file
*get_task_exe_file(struct task_struct
*task
)
1159 struct file
*exe_file
= NULL
;
1160 struct mm_struct
*mm
;
1165 if (!(task
->flags
& PF_KTHREAD
))
1166 exe_file
= get_mm_exe_file(mm
);
1171 EXPORT_SYMBOL(get_task_exe_file
);
1174 * get_task_mm - acquire a reference to the task's mm
1176 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1177 * this kernel workthread has transiently adopted a user mm with use_mm,
1178 * to do its AIO) is not set and if so returns a reference to it, after
1179 * bumping up the use count. User must release the mm via mmput()
1180 * after use. Typically used by /proc and ptrace.
1182 struct mm_struct
*get_task_mm(struct task_struct
*task
)
1184 struct mm_struct
*mm
;
1189 if (task
->flags
& PF_KTHREAD
)
1197 EXPORT_SYMBOL_GPL(get_task_mm
);
1199 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1201 struct mm_struct
*mm
;
1204 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
1206 return ERR_PTR(err
);
1208 mm
= get_task_mm(task
);
1209 if (mm
&& mm
!= current
->mm
&&
1210 !ptrace_may_access(task
, mode
)) {
1212 mm
= ERR_PTR(-EACCES
);
1214 mutex_unlock(&task
->signal
->cred_guard_mutex
);
1219 static void complete_vfork_done(struct task_struct
*tsk
)
1221 struct completion
*vfork
;
1224 vfork
= tsk
->vfork_done
;
1225 if (likely(vfork
)) {
1226 tsk
->vfork_done
= NULL
;
1232 static int wait_for_vfork_done(struct task_struct
*child
,
1233 struct completion
*vfork
)
1237 freezer_do_not_count();
1238 killed
= wait_for_completion_killable(vfork
);
1243 child
->vfork_done
= NULL
;
1247 put_task_struct(child
);
1251 /* Please note the differences between mmput and mm_release.
1252 * mmput is called whenever we stop holding onto a mm_struct,
1253 * error success whatever.
1255 * mm_release is called after a mm_struct has been removed
1256 * from the current process.
1258 * This difference is important for error handling, when we
1259 * only half set up a mm_struct for a new process and need to restore
1260 * the old one. Because we mmput the new mm_struct before
1261 * restoring the old one. . .
1262 * Eric Biederman 10 January 1998
1264 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1266 /* Get rid of any futexes when releasing the mm */
1268 if (unlikely(tsk
->robust_list
)) {
1269 exit_robust_list(tsk
);
1270 tsk
->robust_list
= NULL
;
1272 #ifdef CONFIG_COMPAT
1273 if (unlikely(tsk
->compat_robust_list
)) {
1274 compat_exit_robust_list(tsk
);
1275 tsk
->compat_robust_list
= NULL
;
1278 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1279 exit_pi_state_list(tsk
);
1282 uprobe_free_utask(tsk
);
1284 /* Get rid of any cached register state */
1285 deactivate_mm(tsk
, mm
);
1288 * Signal userspace if we're not exiting with a core dump
1289 * because we want to leave the value intact for debugging
1292 if (tsk
->clear_child_tid
) {
1293 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1294 atomic_read(&mm
->mm_users
) > 1) {
1296 * We don't check the error code - if userspace has
1297 * not set up a proper pointer then tough luck.
1299 put_user(0, tsk
->clear_child_tid
);
1300 do_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1301 1, NULL
, NULL
, 0, 0);
1303 tsk
->clear_child_tid
= NULL
;
1307 * All done, finally we can wake up parent and return this mm to him.
1308 * Also kthread_stop() uses this completion for synchronization.
1310 if (tsk
->vfork_done
)
1311 complete_vfork_done(tsk
);
1315 * Allocate a new mm structure and copy contents from the
1316 * mm structure of the passed in task structure.
1318 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
1320 struct mm_struct
*mm
, *oldmm
= current
->mm
;
1327 memcpy(mm
, oldmm
, sizeof(*mm
));
1329 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1332 err
= dup_mmap(mm
, oldmm
);
1336 mm
->hiwater_rss
= get_mm_rss(mm
);
1337 mm
->hiwater_vm
= mm
->total_vm
;
1339 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1345 /* don't put binfmt in mmput, we haven't got module yet */
1347 mm_init_owner(mm
, NULL
);
1354 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1356 struct mm_struct
*mm
, *oldmm
;
1359 tsk
->min_flt
= tsk
->maj_flt
= 0;
1360 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1361 #ifdef CONFIG_DETECT_HUNG_TASK
1362 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1363 tsk
->last_switch_time
= 0;
1367 tsk
->active_mm
= NULL
;
1370 * Are we cloning a kernel thread?
1372 * We need to steal a active VM for that..
1374 oldmm
= current
->mm
;
1378 /* initialize the new vmacache entries */
1379 vmacache_flush(tsk
);
1381 if (clone_flags
& CLONE_VM
) {
1394 tsk
->active_mm
= mm
;
1401 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1403 struct fs_struct
*fs
= current
->fs
;
1404 if (clone_flags
& CLONE_FS
) {
1405 /* tsk->fs is already what we want */
1406 spin_lock(&fs
->lock
);
1408 spin_unlock(&fs
->lock
);
1412 spin_unlock(&fs
->lock
);
1415 tsk
->fs
= copy_fs_struct(fs
);
1421 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1423 struct files_struct
*oldf
, *newf
;
1427 * A background process may not have any files ...
1429 oldf
= current
->files
;
1433 if (clone_flags
& CLONE_FILES
) {
1434 atomic_inc(&oldf
->count
);
1438 newf
= dup_fd(oldf
, &error
);
1448 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1451 struct io_context
*ioc
= current
->io_context
;
1452 struct io_context
*new_ioc
;
1457 * Share io context with parent, if CLONE_IO is set
1459 if (clone_flags
& CLONE_IO
) {
1461 tsk
->io_context
= ioc
;
1462 } else if (ioprio_valid(ioc
->ioprio
)) {
1463 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1464 if (unlikely(!new_ioc
))
1467 new_ioc
->ioprio
= ioc
->ioprio
;
1468 put_io_context(new_ioc
);
1474 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1476 struct sighand_struct
*sig
;
1478 if (clone_flags
& CLONE_SIGHAND
) {
1479 refcount_inc(¤t
->sighand
->count
);
1482 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1483 rcu_assign_pointer(tsk
->sighand
, sig
);
1487 refcount_set(&sig
->count
, 1);
1488 spin_lock_irq(¤t
->sighand
->siglock
);
1489 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1490 spin_unlock_irq(¤t
->sighand
->siglock
);
1494 void __cleanup_sighand(struct sighand_struct
*sighand
)
1496 if (refcount_dec_and_test(&sighand
->count
)) {
1497 signalfd_cleanup(sighand
);
1499 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1500 * without an RCU grace period, see __lock_task_sighand().
1502 kmem_cache_free(sighand_cachep
, sighand
);
1506 #ifdef CONFIG_POSIX_TIMERS
1508 * Initialize POSIX timer handling for a thread group.
1510 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1512 unsigned long cpu_limit
;
1514 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1515 if (cpu_limit
!= RLIM_INFINITY
) {
1516 sig
->cputime_expires
.prof_exp
= cpu_limit
* NSEC_PER_SEC
;
1517 sig
->cputimer
.running
= true;
1520 /* The timer lists. */
1521 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1522 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1523 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1526 static inline void posix_cpu_timers_init_group(struct signal_struct
*sig
) { }
1529 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1531 struct signal_struct
*sig
;
1533 if (clone_flags
& CLONE_THREAD
)
1536 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1541 sig
->nr_threads
= 1;
1542 atomic_set(&sig
->live
, 1);
1543 refcount_set(&sig
->sigcnt
, 1);
1545 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1546 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1547 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1549 init_waitqueue_head(&sig
->wait_chldexit
);
1550 sig
->curr_target
= tsk
;
1551 init_sigpending(&sig
->shared_pending
);
1552 INIT_HLIST_HEAD(&sig
->multiprocess
);
1553 seqlock_init(&sig
->stats_lock
);
1554 prev_cputime_init(&sig
->prev_cputime
);
1556 #ifdef CONFIG_POSIX_TIMERS
1557 INIT_LIST_HEAD(&sig
->posix_timers
);
1558 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1559 sig
->real_timer
.function
= it_real_fn
;
1562 task_lock(current
->group_leader
);
1563 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1564 task_unlock(current
->group_leader
);
1566 posix_cpu_timers_init_group(sig
);
1568 tty_audit_fork(sig
);
1569 sched_autogroup_fork(sig
);
1571 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1572 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1574 mutex_init(&sig
->cred_guard_mutex
);
1579 static void copy_seccomp(struct task_struct
*p
)
1581 #ifdef CONFIG_SECCOMP
1583 * Must be called with sighand->lock held, which is common to
1584 * all threads in the group. Holding cred_guard_mutex is not
1585 * needed because this new task is not yet running and cannot
1588 assert_spin_locked(¤t
->sighand
->siglock
);
1590 /* Ref-count the new filter user, and assign it. */
1591 get_seccomp_filter(current
);
1592 p
->seccomp
= current
->seccomp
;
1595 * Explicitly enable no_new_privs here in case it got set
1596 * between the task_struct being duplicated and holding the
1597 * sighand lock. The seccomp state and nnp must be in sync.
1599 if (task_no_new_privs(current
))
1600 task_set_no_new_privs(p
);
1603 * If the parent gained a seccomp mode after copying thread
1604 * flags and between before we held the sighand lock, we have
1605 * to manually enable the seccomp thread flag here.
1607 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1608 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1612 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1614 current
->clear_child_tid
= tidptr
;
1616 return task_pid_vnr(current
);
1619 static void rt_mutex_init_task(struct task_struct
*p
)
1621 raw_spin_lock_init(&p
->pi_lock
);
1622 #ifdef CONFIG_RT_MUTEXES
1623 p
->pi_waiters
= RB_ROOT_CACHED
;
1624 p
->pi_top_task
= NULL
;
1625 p
->pi_blocked_on
= NULL
;
1629 #ifdef CONFIG_POSIX_TIMERS
1631 * Initialize POSIX timer handling for a single task.
1633 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1635 tsk
->cputime_expires
.prof_exp
= 0;
1636 tsk
->cputime_expires
.virt_exp
= 0;
1637 tsk
->cputime_expires
.sched_exp
= 0;
1638 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1639 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1640 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1643 static inline void posix_cpu_timers_init(struct task_struct
*tsk
) { }
1646 static inline void init_task_pid_links(struct task_struct
*task
)
1650 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1651 INIT_HLIST_NODE(&task
->pid_links
[type
]);
1656 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1658 if (type
== PIDTYPE_PID
)
1659 task
->thread_pid
= pid
;
1661 task
->signal
->pids
[type
] = pid
;
1664 static inline void rcu_copy_process(struct task_struct
*p
)
1666 #ifdef CONFIG_PREEMPT_RCU
1667 p
->rcu_read_lock_nesting
= 0;
1668 p
->rcu_read_unlock_special
.s
= 0;
1669 p
->rcu_blocked_node
= NULL
;
1670 INIT_LIST_HEAD(&p
->rcu_node_entry
);
1671 #endif /* #ifdef CONFIG_PREEMPT_RCU */
1672 #ifdef CONFIG_TASKS_RCU
1673 p
->rcu_tasks_holdout
= false;
1674 INIT_LIST_HEAD(&p
->rcu_tasks_holdout_list
);
1675 p
->rcu_tasks_idle_cpu
= -1;
1676 #endif /* #ifdef CONFIG_TASKS_RCU */
1679 static void __delayed_free_task(struct rcu_head
*rhp
)
1681 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
1686 static __always_inline
void delayed_free_task(struct task_struct
*tsk
)
1688 if (IS_ENABLED(CONFIG_MEMCG
))
1689 call_rcu(&tsk
->rcu
, __delayed_free_task
);
1695 * This creates a new process as a copy of the old one,
1696 * but does not actually start it yet.
1698 * It copies the registers, and all the appropriate
1699 * parts of the process environment (as per the clone
1700 * flags). The actual kick-off is left to the caller.
1702 static __latent_entropy
struct task_struct
*copy_process(
1703 unsigned long clone_flags
,
1704 unsigned long stack_start
,
1705 unsigned long stack_size
,
1706 int __user
*child_tidptr
,
1713 struct task_struct
*p
;
1714 struct multiprocess_signals delayed
;
1717 * Don't allow sharing the root directory with processes in a different
1720 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1721 return ERR_PTR(-EINVAL
);
1723 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1724 return ERR_PTR(-EINVAL
);
1727 * Thread groups must share signals as well, and detached threads
1728 * can only be started up within the thread group.
1730 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1731 return ERR_PTR(-EINVAL
);
1734 * Shared signal handlers imply shared VM. By way of the above,
1735 * thread groups also imply shared VM. Blocking this case allows
1736 * for various simplifications in other code.
1738 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1739 return ERR_PTR(-EINVAL
);
1742 * Siblings of global init remain as zombies on exit since they are
1743 * not reaped by their parent (swapper). To solve this and to avoid
1744 * multi-rooted process trees, prevent global and container-inits
1745 * from creating siblings.
1747 if ((clone_flags
& CLONE_PARENT
) &&
1748 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1749 return ERR_PTR(-EINVAL
);
1752 * If the new process will be in a different pid or user namespace
1753 * do not allow it to share a thread group with the forking task.
1755 if (clone_flags
& CLONE_THREAD
) {
1756 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1757 (task_active_pid_ns(current
) !=
1758 current
->nsproxy
->pid_ns_for_children
))
1759 return ERR_PTR(-EINVAL
);
1763 * Force any signals received before this point to be delivered
1764 * before the fork happens. Collect up signals sent to multiple
1765 * processes that happen during the fork and delay them so that
1766 * they appear to happen after the fork.
1768 sigemptyset(&delayed
.signal
);
1769 INIT_HLIST_NODE(&delayed
.node
);
1771 spin_lock_irq(¤t
->sighand
->siglock
);
1772 if (!(clone_flags
& CLONE_THREAD
))
1773 hlist_add_head(&delayed
.node
, ¤t
->signal
->multiprocess
);
1774 recalc_sigpending();
1775 spin_unlock_irq(¤t
->sighand
->siglock
);
1776 retval
= -ERESTARTNOINTR
;
1777 if (signal_pending(current
))
1781 p
= dup_task_struct(current
, node
);
1786 * This _must_ happen before we call free_task(), i.e. before we jump
1787 * to any of the bad_fork_* labels. This is to avoid freeing
1788 * p->set_child_tid which is (ab)used as a kthread's data pointer for
1789 * kernel threads (PF_KTHREAD).
1791 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1793 * Clear TID on mm_release()?
1795 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1797 ftrace_graph_init_task(p
);
1799 rt_mutex_init_task(p
);
1801 #ifdef CONFIG_PROVE_LOCKING
1802 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1803 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1806 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1807 task_rlimit(p
, RLIMIT_NPROC
)) {
1808 if (p
->real_cred
->user
!= INIT_USER
&&
1809 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1812 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1814 retval
= copy_creds(p
, clone_flags
);
1819 * If multiple threads are within copy_process(), then this check
1820 * triggers too late. This doesn't hurt, the check is only there
1821 * to stop root fork bombs.
1824 if (nr_threads
>= max_threads
)
1825 goto bad_fork_cleanup_count
;
1827 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1828 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1829 p
->flags
|= PF_FORKNOEXEC
;
1830 INIT_LIST_HEAD(&p
->children
);
1831 INIT_LIST_HEAD(&p
->sibling
);
1832 rcu_copy_process(p
);
1833 p
->vfork_done
= NULL
;
1834 spin_lock_init(&p
->alloc_lock
);
1836 init_sigpending(&p
->pending
);
1838 p
->utime
= p
->stime
= p
->gtime
= 0;
1839 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1840 p
->utimescaled
= p
->stimescaled
= 0;
1842 prev_cputime_init(&p
->prev_cputime
);
1844 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1845 seqcount_init(&p
->vtime
.seqcount
);
1846 p
->vtime
.starttime
= 0;
1847 p
->vtime
.state
= VTIME_INACTIVE
;
1850 #if defined(SPLIT_RSS_COUNTING)
1851 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1854 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1860 task_io_accounting_init(&p
->ioac
);
1861 acct_clear_integrals(p
);
1863 posix_cpu_timers_init(p
);
1865 p
->io_context
= NULL
;
1866 audit_set_context(p
, NULL
);
1869 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1870 if (IS_ERR(p
->mempolicy
)) {
1871 retval
= PTR_ERR(p
->mempolicy
);
1872 p
->mempolicy
= NULL
;
1873 goto bad_fork_cleanup_threadgroup_lock
;
1876 #ifdef CONFIG_CPUSETS
1877 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1878 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1879 seqcount_init(&p
->mems_allowed_seq
);
1881 #ifdef CONFIG_TRACE_IRQFLAGS
1883 p
->hardirqs_enabled
= 0;
1884 p
->hardirq_enable_ip
= 0;
1885 p
->hardirq_enable_event
= 0;
1886 p
->hardirq_disable_ip
= _THIS_IP_
;
1887 p
->hardirq_disable_event
= 0;
1888 p
->softirqs_enabled
= 1;
1889 p
->softirq_enable_ip
= _THIS_IP_
;
1890 p
->softirq_enable_event
= 0;
1891 p
->softirq_disable_ip
= 0;
1892 p
->softirq_disable_event
= 0;
1893 p
->hardirq_context
= 0;
1894 p
->softirq_context
= 0;
1897 p
->pagefault_disabled
= 0;
1899 #ifdef CONFIG_LOCKDEP
1900 p
->lockdep_depth
= 0; /* no locks held yet */
1901 p
->curr_chain_key
= 0;
1902 p
->lockdep_recursion
= 0;
1903 lockdep_init_task(p
);
1906 #ifdef CONFIG_DEBUG_MUTEXES
1907 p
->blocked_on
= NULL
; /* not blocked yet */
1909 #ifdef CONFIG_BCACHE
1910 p
->sequential_io
= 0;
1911 p
->sequential_io_avg
= 0;
1914 /* Perform scheduler related setup. Assign this task to a CPU. */
1915 retval
= sched_fork(clone_flags
, p
);
1917 goto bad_fork_cleanup_policy
;
1919 retval
= perf_event_init_task(p
);
1921 goto bad_fork_cleanup_policy
;
1922 retval
= audit_alloc(p
);
1924 goto bad_fork_cleanup_perf
;
1925 /* copy all the process information */
1927 retval
= security_task_alloc(p
, clone_flags
);
1929 goto bad_fork_cleanup_audit
;
1930 retval
= copy_semundo(clone_flags
, p
);
1932 goto bad_fork_cleanup_security
;
1933 retval
= copy_files(clone_flags
, p
);
1935 goto bad_fork_cleanup_semundo
;
1936 retval
= copy_fs(clone_flags
, p
);
1938 goto bad_fork_cleanup_files
;
1939 retval
= copy_sighand(clone_flags
, p
);
1941 goto bad_fork_cleanup_fs
;
1942 retval
= copy_signal(clone_flags
, p
);
1944 goto bad_fork_cleanup_sighand
;
1945 retval
= copy_mm(clone_flags
, p
);
1947 goto bad_fork_cleanup_signal
;
1948 retval
= copy_namespaces(clone_flags
, p
);
1950 goto bad_fork_cleanup_mm
;
1951 retval
= copy_io(clone_flags
, p
);
1953 goto bad_fork_cleanup_namespaces
;
1954 retval
= copy_thread_tls(clone_flags
, stack_start
, stack_size
, p
, tls
);
1956 goto bad_fork_cleanup_io
;
1958 stackleak_task_init(p
);
1960 if (pid
!= &init_struct_pid
) {
1961 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1963 retval
= PTR_ERR(pid
);
1964 goto bad_fork_cleanup_thread
;
1972 p
->robust_list
= NULL
;
1973 #ifdef CONFIG_COMPAT
1974 p
->compat_robust_list
= NULL
;
1976 INIT_LIST_HEAD(&p
->pi_state_list
);
1977 p
->pi_state_cache
= NULL
;
1980 * sigaltstack should be cleared when sharing the same VM
1982 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1986 * Syscall tracing and stepping should be turned off in the
1987 * child regardless of CLONE_PTRACE.
1989 user_disable_single_step(p
);
1990 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1991 #ifdef TIF_SYSCALL_EMU
1992 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1994 clear_all_latency_tracing(p
);
1996 /* ok, now we should be set up.. */
1997 p
->pid
= pid_nr(pid
);
1998 if (clone_flags
& CLONE_THREAD
) {
1999 p
->exit_signal
= -1;
2000 p
->group_leader
= current
->group_leader
;
2001 p
->tgid
= current
->tgid
;
2003 if (clone_flags
& CLONE_PARENT
)
2004 p
->exit_signal
= current
->group_leader
->exit_signal
;
2006 p
->exit_signal
= (clone_flags
& CSIGNAL
);
2007 p
->group_leader
= p
;
2012 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
2013 p
->dirty_paused_when
= 0;
2015 p
->pdeath_signal
= 0;
2016 INIT_LIST_HEAD(&p
->thread_group
);
2017 p
->task_works
= NULL
;
2019 cgroup_threadgroup_change_begin(current
);
2021 * Ensure that the cgroup subsystem policies allow the new process to be
2022 * forked. It should be noted the the new process's css_set can be changed
2023 * between here and cgroup_post_fork() if an organisation operation is in
2026 retval
= cgroup_can_fork(p
);
2028 goto bad_fork_free_pid
;
2031 * From this point on we must avoid any synchronous user-space
2032 * communication until we take the tasklist-lock. In particular, we do
2033 * not want user-space to be able to predict the process start-time by
2034 * stalling fork(2) after we recorded the start_time but before it is
2035 * visible to the system.
2038 p
->start_time
= ktime_get_ns();
2039 p
->real_start_time
= ktime_get_boot_ns();
2042 * Make it visible to the rest of the system, but dont wake it up yet.
2043 * Need tasklist lock for parent etc handling!
2045 write_lock_irq(&tasklist_lock
);
2047 /* CLONE_PARENT re-uses the old parent */
2048 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
2049 p
->real_parent
= current
->real_parent
;
2050 p
->parent_exec_id
= current
->parent_exec_id
;
2052 p
->real_parent
= current
;
2053 p
->parent_exec_id
= current
->self_exec_id
;
2056 klp_copy_process(p
);
2058 spin_lock(¤t
->sighand
->siglock
);
2061 * Copy seccomp details explicitly here, in case they were changed
2062 * before holding sighand lock.
2066 rseq_fork(p
, clone_flags
);
2068 /* Don't start children in a dying pid namespace */
2069 if (unlikely(!(ns_of_pid(pid
)->pid_allocated
& PIDNS_ADDING
))) {
2071 goto bad_fork_cancel_cgroup
;
2074 /* Let kill terminate clone/fork in the middle */
2075 if (fatal_signal_pending(current
)) {
2077 goto bad_fork_cancel_cgroup
;
2081 init_task_pid_links(p
);
2082 if (likely(p
->pid
)) {
2083 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
2085 init_task_pid(p
, PIDTYPE_PID
, pid
);
2086 if (thread_group_leader(p
)) {
2087 init_task_pid(p
, PIDTYPE_TGID
, pid
);
2088 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
2089 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
2091 if (is_child_reaper(pid
)) {
2092 ns_of_pid(pid
)->child_reaper
= p
;
2093 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
2095 p
->signal
->shared_pending
.signal
= delayed
.signal
;
2096 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
2098 * Inherit has_child_subreaper flag under the same
2099 * tasklist_lock with adding child to the process tree
2100 * for propagate_has_child_subreaper optimization.
2102 p
->signal
->has_child_subreaper
= p
->real_parent
->signal
->has_child_subreaper
||
2103 p
->real_parent
->signal
->is_child_subreaper
;
2104 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
2105 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
2106 attach_pid(p
, PIDTYPE_TGID
);
2107 attach_pid(p
, PIDTYPE_PGID
);
2108 attach_pid(p
, PIDTYPE_SID
);
2109 __this_cpu_inc(process_counts
);
2111 current
->signal
->nr_threads
++;
2112 atomic_inc(¤t
->signal
->live
);
2113 refcount_inc(¤t
->signal
->sigcnt
);
2114 task_join_group_stop(p
);
2115 list_add_tail_rcu(&p
->thread_group
,
2116 &p
->group_leader
->thread_group
);
2117 list_add_tail_rcu(&p
->thread_node
,
2118 &p
->signal
->thread_head
);
2120 attach_pid(p
, PIDTYPE_PID
);
2124 hlist_del_init(&delayed
.node
);
2125 spin_unlock(¤t
->sighand
->siglock
);
2126 syscall_tracepoint_update(p
);
2127 write_unlock_irq(&tasklist_lock
);
2129 proc_fork_connector(p
);
2130 cgroup_post_fork(p
);
2131 cgroup_threadgroup_change_end(current
);
2134 trace_task_newtask(p
, clone_flags
);
2135 uprobe_copy_process(p
, clone_flags
);
2139 bad_fork_cancel_cgroup
:
2140 spin_unlock(¤t
->sighand
->siglock
);
2141 write_unlock_irq(&tasklist_lock
);
2142 cgroup_cancel_fork(p
);
2144 cgroup_threadgroup_change_end(current
);
2145 if (pid
!= &init_struct_pid
)
2147 bad_fork_cleanup_thread
:
2149 bad_fork_cleanup_io
:
2152 bad_fork_cleanup_namespaces
:
2153 exit_task_namespaces(p
);
2154 bad_fork_cleanup_mm
:
2156 mm_clear_owner(p
->mm
, p
);
2159 bad_fork_cleanup_signal
:
2160 if (!(clone_flags
& CLONE_THREAD
))
2161 free_signal_struct(p
->signal
);
2162 bad_fork_cleanup_sighand
:
2163 __cleanup_sighand(p
->sighand
);
2164 bad_fork_cleanup_fs
:
2165 exit_fs(p
); /* blocking */
2166 bad_fork_cleanup_files
:
2167 exit_files(p
); /* blocking */
2168 bad_fork_cleanup_semundo
:
2170 bad_fork_cleanup_security
:
2171 security_task_free(p
);
2172 bad_fork_cleanup_audit
:
2174 bad_fork_cleanup_perf
:
2175 perf_event_free_task(p
);
2176 bad_fork_cleanup_policy
:
2177 lockdep_free_task(p
);
2179 mpol_put(p
->mempolicy
);
2180 bad_fork_cleanup_threadgroup_lock
:
2182 delayacct_tsk_free(p
);
2183 bad_fork_cleanup_count
:
2184 atomic_dec(&p
->cred
->user
->processes
);
2187 p
->state
= TASK_DEAD
;
2189 delayed_free_task(p
);
2191 spin_lock_irq(¤t
->sighand
->siglock
);
2192 hlist_del_init(&delayed
.node
);
2193 spin_unlock_irq(¤t
->sighand
->siglock
);
2194 return ERR_PTR(retval
);
2197 static inline void init_idle_pids(struct task_struct
*idle
)
2201 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
2202 INIT_HLIST_NODE(&idle
->pid_links
[type
]); /* not really needed */
2203 init_task_pid(idle
, type
, &init_struct_pid
);
2207 struct task_struct
*fork_idle(int cpu
)
2209 struct task_struct
*task
;
2210 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0, 0,
2212 if (!IS_ERR(task
)) {
2213 init_idle_pids(task
);
2214 init_idle(task
, cpu
);
2221 * Ok, this is the main fork-routine.
2223 * It copies the process, and if successful kick-starts
2224 * it and waits for it to finish using the VM if required.
2226 long _do_fork(unsigned long clone_flags
,
2227 unsigned long stack_start
,
2228 unsigned long stack_size
,
2229 int __user
*parent_tidptr
,
2230 int __user
*child_tidptr
,
2233 struct completion vfork
;
2235 struct task_struct
*p
;
2240 * Determine whether and which event to report to ptracer. When
2241 * called from kernel_thread or CLONE_UNTRACED is explicitly
2242 * requested, no event is reported; otherwise, report if the event
2243 * for the type of forking is enabled.
2245 if (!(clone_flags
& CLONE_UNTRACED
)) {
2246 if (clone_flags
& CLONE_VFORK
)
2247 trace
= PTRACE_EVENT_VFORK
;
2248 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
2249 trace
= PTRACE_EVENT_CLONE
;
2251 trace
= PTRACE_EVENT_FORK
;
2253 if (likely(!ptrace_event_enabled(current
, trace
)))
2257 p
= copy_process(clone_flags
, stack_start
, stack_size
,
2258 child_tidptr
, NULL
, trace
, tls
, NUMA_NO_NODE
);
2259 add_latent_entropy();
2265 * Do this prior waking up the new thread - the thread pointer
2266 * might get invalid after that point, if the thread exits quickly.
2268 trace_sched_process_fork(current
, p
);
2270 pid
= get_task_pid(p
, PIDTYPE_PID
);
2273 if (clone_flags
& CLONE_PARENT_SETTID
)
2274 put_user(nr
, parent_tidptr
);
2276 if (clone_flags
& CLONE_VFORK
) {
2277 p
->vfork_done
= &vfork
;
2278 init_completion(&vfork
);
2282 wake_up_new_task(p
);
2284 /* forking complete and child started to run, tell ptracer */
2285 if (unlikely(trace
))
2286 ptrace_event_pid(trace
, pid
);
2288 if (clone_flags
& CLONE_VFORK
) {
2289 if (!wait_for_vfork_done(p
, &vfork
))
2290 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
2297 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
2298 /* For compatibility with architectures that call do_fork directly rather than
2299 * using the syscall entry points below. */
2300 long do_fork(unsigned long clone_flags
,
2301 unsigned long stack_start
,
2302 unsigned long stack_size
,
2303 int __user
*parent_tidptr
,
2304 int __user
*child_tidptr
)
2306 return _do_fork(clone_flags
, stack_start
, stack_size
,
2307 parent_tidptr
, child_tidptr
, 0);
2312 * Create a kernel thread.
2314 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2316 return _do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
2317 (unsigned long)arg
, NULL
, NULL
, 0);
2320 #ifdef __ARCH_WANT_SYS_FORK
2321 SYSCALL_DEFINE0(fork
)
2324 return _do_fork(SIGCHLD
, 0, 0, NULL
, NULL
, 0);
2326 /* can not support in nommu mode */
2332 #ifdef __ARCH_WANT_SYS_VFORK
2333 SYSCALL_DEFINE0(vfork
)
2335 return _do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
2340 #ifdef __ARCH_WANT_SYS_CLONE
2341 #ifdef CONFIG_CLONE_BACKWARDS
2342 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2343 int __user
*, parent_tidptr
,
2345 int __user
*, child_tidptr
)
2346 #elif defined(CONFIG_CLONE_BACKWARDS2)
2347 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2348 int __user
*, parent_tidptr
,
2349 int __user
*, child_tidptr
,
2351 #elif defined(CONFIG_CLONE_BACKWARDS3)
2352 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2354 int __user
*, parent_tidptr
,
2355 int __user
*, child_tidptr
,
2358 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2359 int __user
*, parent_tidptr
,
2360 int __user
*, child_tidptr
,
2364 return _do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
, tls
);
2368 void walk_process_tree(struct task_struct
*top
, proc_visitor visitor
, void *data
)
2370 struct task_struct
*leader
, *parent
, *child
;
2373 read_lock(&tasklist_lock
);
2374 leader
= top
= top
->group_leader
;
2376 for_each_thread(leader
, parent
) {
2377 list_for_each_entry(child
, &parent
->children
, sibling
) {
2378 res
= visitor(child
, data
);
2390 if (leader
!= top
) {
2392 parent
= child
->real_parent
;
2393 leader
= parent
->group_leader
;
2397 read_unlock(&tasklist_lock
);
2400 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2401 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2404 static void sighand_ctor(void *data
)
2406 struct sighand_struct
*sighand
= data
;
2408 spin_lock_init(&sighand
->siglock
);
2409 init_waitqueue_head(&sighand
->signalfd_wqh
);
2412 void __init
proc_caches_init(void)
2414 unsigned int mm_size
;
2416 sighand_cachep
= kmem_cache_create("sighand_cache",
2417 sizeof(struct sighand_struct
), 0,
2418 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_TYPESAFE_BY_RCU
|
2419 SLAB_ACCOUNT
, sighand_ctor
);
2420 signal_cachep
= kmem_cache_create("signal_cache",
2421 sizeof(struct signal_struct
), 0,
2422 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2424 files_cachep
= kmem_cache_create("files_cache",
2425 sizeof(struct files_struct
), 0,
2426 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2428 fs_cachep
= kmem_cache_create("fs_cache",
2429 sizeof(struct fs_struct
), 0,
2430 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2434 * The mm_cpumask is located at the end of mm_struct, and is
2435 * dynamically sized based on the maximum CPU number this system
2436 * can have, taking hotplug into account (nr_cpu_ids).
2438 mm_size
= sizeof(struct mm_struct
) + cpumask_size();
2440 mm_cachep
= kmem_cache_create_usercopy("mm_struct",
2441 mm_size
, ARCH_MIN_MMSTRUCT_ALIGN
,
2442 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_ACCOUNT
,
2443 offsetof(struct mm_struct
, saved_auxv
),
2444 sizeof_field(struct mm_struct
, saved_auxv
),
2446 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2448 nsproxy_cache_init();
2452 * Check constraints on flags passed to the unshare system call.
2454 static int check_unshare_flags(unsigned long unshare_flags
)
2456 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2457 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2458 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2459 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
))
2462 * Not implemented, but pretend it works if there is nothing
2463 * to unshare. Note that unsharing the address space or the
2464 * signal handlers also need to unshare the signal queues (aka
2467 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2468 if (!thread_group_empty(current
))
2471 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2472 if (refcount_read(¤t
->sighand
->count
) > 1)
2475 if (unshare_flags
& CLONE_VM
) {
2476 if (!current_is_single_threaded())
2484 * Unshare the filesystem structure if it is being shared
2486 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2488 struct fs_struct
*fs
= current
->fs
;
2490 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2493 /* don't need lock here; in the worst case we'll do useless copy */
2497 *new_fsp
= copy_fs_struct(fs
);
2505 * Unshare file descriptor table if it is being shared
2507 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2509 struct files_struct
*fd
= current
->files
;
2512 if ((unshare_flags
& CLONE_FILES
) &&
2513 (fd
&& atomic_read(&fd
->count
) > 1)) {
2514 *new_fdp
= dup_fd(fd
, &error
);
2523 * unshare allows a process to 'unshare' part of the process
2524 * context which was originally shared using clone. copy_*
2525 * functions used by do_fork() cannot be used here directly
2526 * because they modify an inactive task_struct that is being
2527 * constructed. Here we are modifying the current, active,
2530 int ksys_unshare(unsigned long unshare_flags
)
2532 struct fs_struct
*fs
, *new_fs
= NULL
;
2533 struct files_struct
*fd
, *new_fd
= NULL
;
2534 struct cred
*new_cred
= NULL
;
2535 struct nsproxy
*new_nsproxy
= NULL
;
2540 * If unsharing a user namespace must also unshare the thread group
2541 * and unshare the filesystem root and working directories.
2543 if (unshare_flags
& CLONE_NEWUSER
)
2544 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2546 * If unsharing vm, must also unshare signal handlers.
2548 if (unshare_flags
& CLONE_VM
)
2549 unshare_flags
|= CLONE_SIGHAND
;
2551 * If unsharing a signal handlers, must also unshare the signal queues.
2553 if (unshare_flags
& CLONE_SIGHAND
)
2554 unshare_flags
|= CLONE_THREAD
;
2556 * If unsharing namespace, must also unshare filesystem information.
2558 if (unshare_flags
& CLONE_NEWNS
)
2559 unshare_flags
|= CLONE_FS
;
2561 err
= check_unshare_flags(unshare_flags
);
2563 goto bad_unshare_out
;
2565 * CLONE_NEWIPC must also detach from the undolist: after switching
2566 * to a new ipc namespace, the semaphore arrays from the old
2567 * namespace are unreachable.
2569 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2571 err
= unshare_fs(unshare_flags
, &new_fs
);
2573 goto bad_unshare_out
;
2574 err
= unshare_fd(unshare_flags
, &new_fd
);
2576 goto bad_unshare_cleanup_fs
;
2577 err
= unshare_userns(unshare_flags
, &new_cred
);
2579 goto bad_unshare_cleanup_fd
;
2580 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2583 goto bad_unshare_cleanup_cred
;
2585 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2588 * CLONE_SYSVSEM is equivalent to sys_exit().
2592 if (unshare_flags
& CLONE_NEWIPC
) {
2593 /* Orphan segments in old ns (see sem above). */
2595 shm_init_task(current
);
2599 switch_task_namespaces(current
, new_nsproxy
);
2605 spin_lock(&fs
->lock
);
2606 current
->fs
= new_fs
;
2611 spin_unlock(&fs
->lock
);
2615 fd
= current
->files
;
2616 current
->files
= new_fd
;
2620 task_unlock(current
);
2623 /* Install the new user namespace */
2624 commit_creds(new_cred
);
2629 perf_event_namespaces(current
);
2631 bad_unshare_cleanup_cred
:
2634 bad_unshare_cleanup_fd
:
2636 put_files_struct(new_fd
);
2638 bad_unshare_cleanup_fs
:
2640 free_fs_struct(new_fs
);
2646 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
2648 return ksys_unshare(unshare_flags
);
2652 * Helper to unshare the files of the current task.
2653 * We don't want to expose copy_files internals to
2654 * the exec layer of the kernel.
2657 int unshare_files(struct files_struct
**displaced
)
2659 struct task_struct
*task
= current
;
2660 struct files_struct
*copy
= NULL
;
2663 error
= unshare_fd(CLONE_FILES
, ©
);
2664 if (error
|| !copy
) {
2668 *displaced
= task
->files
;
2675 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2676 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2680 int threads
= max_threads
;
2681 int min
= MIN_THREADS
;
2682 int max
= MAX_THREADS
;
2689 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2693 set_max_threads(threads
);