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/init.h>
16 #include <linux/unistd.h>
17 #include <linux/module.h>
18 #include <linux/vmalloc.h>
19 #include <linux/completion.h>
20 #include <linux/personality.h>
21 #include <linux/mempolicy.h>
22 #include <linux/sem.h>
23 #include <linux/file.h>
24 #include <linux/fdtable.h>
25 #include <linux/iocontext.h>
26 #include <linux/key.h>
27 #include <linux/binfmts.h>
28 #include <linux/mman.h>
29 #include <linux/mmu_notifier.h>
32 #include <linux/vmacache.h>
33 #include <linux/nsproxy.h>
34 #include <linux/capability.h>
35 #include <linux/cpu.h>
36 #include <linux/cgroup.h>
37 #include <linux/security.h>
38 #include <linux/hugetlb.h>
39 #include <linux/seccomp.h>
40 #include <linux/swap.h>
41 #include <linux/syscalls.h>
42 #include <linux/jiffies.h>
43 #include <linux/futex.h>
44 #include <linux/compat.h>
45 #include <linux/kthread.h>
46 #include <linux/task_io_accounting_ops.h>
47 #include <linux/rcupdate.h>
48 #include <linux/ptrace.h>
49 #include <linux/mount.h>
50 #include <linux/audit.h>
51 #include <linux/memcontrol.h>
52 #include <linux/ftrace.h>
53 #include <linux/proc_fs.h>
54 #include <linux/profile.h>
55 #include <linux/rmap.h>
56 #include <linux/ksm.h>
57 #include <linux/acct.h>
58 #include <linux/tsacct_kern.h>
59 #include <linux/cn_proc.h>
60 #include <linux/freezer.h>
61 #include <linux/delayacct.h>
62 #include <linux/taskstats_kern.h>
63 #include <linux/random.h>
64 #include <linux/tty.h>
65 #include <linux/blkdev.h>
66 #include <linux/fs_struct.h>
67 #include <linux/magic.h>
68 #include <linux/perf_event.h>
69 #include <linux/posix-timers.h>
70 #include <linux/user-return-notifier.h>
71 #include <linux/oom.h>
72 #include <linux/khugepaged.h>
73 #include <linux/signalfd.h>
74 #include <linux/uprobes.h>
75 #include <linux/aio.h>
76 #include <linux/compiler.h>
77 #include <linux/sysctl.h>
78 #include <linux/kcov.h>
80 #include <asm/pgtable.h>
81 #include <asm/pgalloc.h>
82 #include <linux/uaccess.h>
83 #include <asm/mmu_context.h>
84 #include <asm/cacheflush.h>
85 #include <asm/tlbflush.h>
87 #include <trace/events/sched.h>
89 #define CREATE_TRACE_POINTS
90 #include <trace/events/task.h>
92 extern int unprivileged_userns_clone
;
94 #define unprivileged_userns_clone 0
98 * Minimum number of threads to boot the kernel
100 #define MIN_THREADS 20
103 * Maximum number of threads
105 #define MAX_THREADS FUTEX_TID_MASK
108 * Protected counters by write_lock_irq(&tasklist_lock)
110 unsigned long total_forks
; /* Handle normal Linux uptimes. */
111 int nr_threads
; /* The idle threads do not count.. */
113 int max_threads
; /* tunable limit on nr_threads */
115 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
117 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
119 #ifdef CONFIG_PROVE_RCU
120 int lockdep_tasklist_lock_is_held(void)
122 return lockdep_is_held(&tasklist_lock
);
124 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
125 #endif /* #ifdef CONFIG_PROVE_RCU */
127 int nr_processes(void)
132 for_each_possible_cpu(cpu
)
133 total
+= per_cpu(process_counts
, cpu
);
138 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
142 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
143 static struct kmem_cache
*task_struct_cachep
;
145 static inline struct task_struct
*alloc_task_struct_node(int node
)
147 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
150 static inline void free_task_struct(struct task_struct
*tsk
)
152 kmem_cache_free(task_struct_cachep
, tsk
);
156 void __weak
arch_release_thread_stack(unsigned long *stack
)
160 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
163 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
164 * kmemcache based allocator.
166 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
168 #ifdef CONFIG_VMAP_STACK
170 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
171 * flush. Try to minimize the number of calls by caching stacks.
173 #define NR_CACHED_STACKS 2
174 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
177 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
179 #ifdef CONFIG_VMAP_STACK
184 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
185 struct vm_struct
*s
= this_cpu_read(cached_stacks
[i
]);
189 this_cpu_write(cached_stacks
[i
], NULL
);
191 tsk
->stack_vm_area
= s
;
197 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_SIZE
,
198 VMALLOC_START
, VMALLOC_END
,
199 THREADINFO_GFP
| __GFP_HIGHMEM
,
201 0, node
, __builtin_return_address(0));
204 * We can't call find_vm_area() in interrupt context, and
205 * free_thread_stack() can be called in interrupt context,
206 * so cache the vm_struct.
209 tsk
->stack_vm_area
= find_vm_area(stack
);
212 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
215 return page
? page_address(page
) : NULL
;
219 static inline void free_thread_stack(struct task_struct
*tsk
)
221 #ifdef CONFIG_VMAP_STACK
222 if (task_stack_vm_area(tsk
)) {
226 local_irq_save(flags
);
227 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
228 if (this_cpu_read(cached_stacks
[i
]))
231 this_cpu_write(cached_stacks
[i
], tsk
->stack_vm_area
);
232 local_irq_restore(flags
);
235 local_irq_restore(flags
);
237 vfree_atomic(tsk
->stack
);
242 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
245 static struct kmem_cache
*thread_stack_cache
;
247 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
250 return kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
253 static void free_thread_stack(struct task_struct
*tsk
)
255 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
258 void thread_stack_cache_init(void)
260 thread_stack_cache
= kmem_cache_create("thread_stack", THREAD_SIZE
,
261 THREAD_SIZE
, 0, NULL
);
262 BUG_ON(thread_stack_cache
== NULL
);
267 /* SLAB cache for signal_struct structures (tsk->signal) */
268 static struct kmem_cache
*signal_cachep
;
270 /* SLAB cache for sighand_struct structures (tsk->sighand) */
271 struct kmem_cache
*sighand_cachep
;
273 /* SLAB cache for files_struct structures (tsk->files) */
274 struct kmem_cache
*files_cachep
;
276 /* SLAB cache for fs_struct structures (tsk->fs) */
277 struct kmem_cache
*fs_cachep
;
279 /* SLAB cache for vm_area_struct structures */
280 struct kmem_cache
*vm_area_cachep
;
282 /* SLAB cache for mm_struct structures (tsk->mm) */
283 static struct kmem_cache
*mm_cachep
;
285 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
287 void *stack
= task_stack_page(tsk
);
288 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
290 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
295 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
297 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
298 mod_zone_page_state(page_zone(vm
->pages
[i
]),
300 PAGE_SIZE
/ 1024 * account
);
303 /* All stack pages belong to the same memcg. */
304 memcg_kmem_update_page_stat(vm
->pages
[0], MEMCG_KERNEL_STACK_KB
,
305 account
* (THREAD_SIZE
/ 1024));
308 * All stack pages are in the same zone and belong to the
311 struct page
*first_page
= virt_to_page(stack
);
313 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
314 THREAD_SIZE
/ 1024 * account
);
316 memcg_kmem_update_page_stat(first_page
, MEMCG_KERNEL_STACK_KB
,
317 account
* (THREAD_SIZE
/ 1024));
321 static void release_task_stack(struct task_struct
*tsk
)
323 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
324 return; /* Better to leak the stack than to free prematurely */
326 account_kernel_stack(tsk
, -1);
327 arch_release_thread_stack(tsk
->stack
);
328 free_thread_stack(tsk
);
330 #ifdef CONFIG_VMAP_STACK
331 tsk
->stack_vm_area
= NULL
;
335 #ifdef CONFIG_THREAD_INFO_IN_TASK
336 void put_task_stack(struct task_struct
*tsk
)
338 if (atomic_dec_and_test(&tsk
->stack_refcount
))
339 release_task_stack(tsk
);
343 void free_task(struct task_struct
*tsk
)
345 #ifndef CONFIG_THREAD_INFO_IN_TASK
347 * The task is finally done with both the stack and thread_info,
350 release_task_stack(tsk
);
353 * If the task had a separate stack allocation, it should be gone
356 WARN_ON_ONCE(atomic_read(&tsk
->stack_refcount
) != 0);
358 rt_mutex_debug_task_free(tsk
);
359 ftrace_graph_exit_task(tsk
);
360 put_seccomp_filter(tsk
);
361 arch_release_task_struct(tsk
);
362 if (tsk
->flags
& PF_KTHREAD
)
363 free_kthread_struct(tsk
);
364 free_task_struct(tsk
);
366 EXPORT_SYMBOL(free_task
);
368 static inline void free_signal_struct(struct signal_struct
*sig
)
370 taskstats_tgid_free(sig
);
371 sched_autogroup_exit(sig
);
373 * __mmdrop is not safe to call from softirq context on x86 due to
374 * pgd_dtor so postpone it to the async context
377 mmdrop_async(sig
->oom_mm
);
378 kmem_cache_free(signal_cachep
, sig
);
381 static inline void put_signal_struct(struct signal_struct
*sig
)
383 if (atomic_dec_and_test(&sig
->sigcnt
))
384 free_signal_struct(sig
);
387 void __put_task_struct(struct task_struct
*tsk
)
389 WARN_ON(!tsk
->exit_state
);
390 WARN_ON(atomic_read(&tsk
->usage
));
391 WARN_ON(tsk
== current
);
395 security_task_free(tsk
);
397 delayacct_tsk_free(tsk
);
398 put_signal_struct(tsk
->signal
);
400 if (!profile_handoff_task(tsk
))
403 EXPORT_SYMBOL_GPL(__put_task_struct
);
405 void __init __weak
arch_task_cache_init(void) { }
410 static void set_max_threads(unsigned int max_threads_suggested
)
415 * The number of threads shall be limited such that the thread
416 * structures may only consume a small part of the available memory.
418 if (fls64(totalram_pages
) + fls64(PAGE_SIZE
) > 64)
419 threads
= MAX_THREADS
;
421 threads
= div64_u64((u64
) totalram_pages
* (u64
) PAGE_SIZE
,
422 (u64
) THREAD_SIZE
* 8UL);
424 if (threads
> max_threads_suggested
)
425 threads
= max_threads_suggested
;
427 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
430 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
431 /* Initialized by the architecture: */
432 int arch_task_struct_size __read_mostly
;
435 void __init
fork_init(void)
438 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
439 #ifndef ARCH_MIN_TASKALIGN
440 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
442 /* create a slab on which task_structs can be allocated */
443 task_struct_cachep
= kmem_cache_create("task_struct",
444 arch_task_struct_size
, ARCH_MIN_TASKALIGN
,
445 SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
, NULL
);
448 /* do the arch specific task caches init */
449 arch_task_cache_init();
451 set_max_threads(MAX_THREADS
);
453 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
454 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
455 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
456 init_task
.signal
->rlim
[RLIMIT_NPROC
];
458 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
459 init_user_ns
.ucount_max
[i
] = max_threads
/2;
463 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
464 struct task_struct
*src
)
470 void set_task_stack_end_magic(struct task_struct
*tsk
)
472 unsigned long *stackend
;
474 stackend
= end_of_stack(tsk
);
475 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
478 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
480 struct task_struct
*tsk
;
481 unsigned long *stack
;
482 struct vm_struct
*stack_vm_area
;
485 if (node
== NUMA_NO_NODE
)
486 node
= tsk_fork_get_node(orig
);
487 tsk
= alloc_task_struct_node(node
);
491 stack
= alloc_thread_stack_node(tsk
, node
);
495 stack_vm_area
= task_stack_vm_area(tsk
);
497 err
= arch_dup_task_struct(tsk
, orig
);
500 * arch_dup_task_struct() clobbers the stack-related fields. Make
501 * sure they're properly initialized before using any stack-related
505 #ifdef CONFIG_VMAP_STACK
506 tsk
->stack_vm_area
= stack_vm_area
;
508 #ifdef CONFIG_THREAD_INFO_IN_TASK
509 atomic_set(&tsk
->stack_refcount
, 1);
515 #ifdef CONFIG_SECCOMP
517 * We must handle setting up seccomp filters once we're under
518 * the sighand lock in case orig has changed between now and
519 * then. Until then, filter must be NULL to avoid messing up
520 * the usage counts on the error path calling free_task.
522 tsk
->seccomp
.filter
= NULL
;
525 setup_thread_stack(tsk
, orig
);
526 clear_user_return_notifier(tsk
);
527 clear_tsk_need_resched(tsk
);
528 set_task_stack_end_magic(tsk
);
530 #ifdef CONFIG_CC_STACKPROTECTOR
531 tsk
->stack_canary
= get_random_int();
535 * One for us, one for whoever does the "release_task()" (usually
538 atomic_set(&tsk
->usage
, 2);
539 #ifdef CONFIG_BLK_DEV_IO_TRACE
542 tsk
->splice_pipe
= NULL
;
543 tsk
->task_frag
.page
= NULL
;
544 tsk
->wake_q
.next
= NULL
;
546 account_kernel_stack(tsk
, 1);
553 free_thread_stack(tsk
);
555 free_task_struct(tsk
);
560 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
561 struct mm_struct
*oldmm
)
563 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
564 struct rb_node
**rb_link
, *rb_parent
;
566 unsigned long charge
;
568 uprobe_start_dup_mmap();
569 if (down_write_killable(&oldmm
->mmap_sem
)) {
571 goto fail_uprobe_end
;
573 flush_cache_dup_mm(oldmm
);
574 uprobe_dup_mmap(oldmm
, mm
);
576 * Not linked in yet - no deadlock potential:
578 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
580 /* No ordering required: file already has been exposed. */
581 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
583 mm
->total_vm
= oldmm
->total_vm
;
584 mm
->data_vm
= oldmm
->data_vm
;
585 mm
->exec_vm
= oldmm
->exec_vm
;
586 mm
->stack_vm
= oldmm
->stack_vm
;
588 rb_link
= &mm
->mm_rb
.rb_node
;
591 retval
= ksm_fork(mm
, oldmm
);
594 retval
= khugepaged_fork(mm
, oldmm
);
599 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
602 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
603 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
607 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
608 unsigned long len
= vma_pages(mpnt
);
610 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
614 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
618 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
619 retval
= vma_dup_policy(mpnt
, tmp
);
621 goto fail_nomem_policy
;
623 if (anon_vma_fork(tmp
, mpnt
))
624 goto fail_nomem_anon_vma_fork
;
626 ~(VM_LOCKED
|VM_LOCKONFAULT
|VM_UFFD_MISSING
|VM_UFFD_WP
);
627 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
628 tmp
->vm_userfaultfd_ctx
= NULL_VM_UFFD_CTX
;
631 struct inode
*inode
= file_inode(file
);
632 struct address_space
*mapping
= file
->f_mapping
;
635 if (tmp
->vm_flags
& VM_DENYWRITE
)
636 atomic_dec(&inode
->i_writecount
);
637 i_mmap_lock_write(mapping
);
638 if (tmp
->vm_flags
& VM_SHARED
)
639 atomic_inc(&mapping
->i_mmap_writable
);
640 flush_dcache_mmap_lock(mapping
);
641 /* insert tmp into the share list, just after mpnt */
642 vma_interval_tree_insert_after(tmp
, mpnt
,
644 flush_dcache_mmap_unlock(mapping
);
645 i_mmap_unlock_write(mapping
);
649 * Clear hugetlb-related page reserves for children. This only
650 * affects MAP_PRIVATE mappings. Faults generated by the child
651 * are not guaranteed to succeed, even if read-only
653 if (is_vm_hugetlb_page(tmp
))
654 reset_vma_resv_huge_pages(tmp
);
657 * Link in the new vma and copy the page table entries.
660 pprev
= &tmp
->vm_next
;
664 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
665 rb_link
= &tmp
->vm_rb
.rb_right
;
666 rb_parent
= &tmp
->vm_rb
;
669 retval
= copy_page_range(mm
, oldmm
, mpnt
);
671 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
672 tmp
->vm_ops
->open(tmp
);
677 /* a new mm has just been created */
678 arch_dup_mmap(oldmm
, mm
);
681 up_write(&mm
->mmap_sem
);
683 up_write(&oldmm
->mmap_sem
);
685 uprobe_end_dup_mmap();
687 fail_nomem_anon_vma_fork
:
688 mpol_put(vma_policy(tmp
));
690 kmem_cache_free(vm_area_cachep
, tmp
);
693 vm_unacct_memory(charge
);
697 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
699 mm
->pgd
= pgd_alloc(mm
);
700 if (unlikely(!mm
->pgd
))
705 static inline void mm_free_pgd(struct mm_struct
*mm
)
707 pgd_free(mm
, mm
->pgd
);
710 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
712 down_write(&oldmm
->mmap_sem
);
713 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
714 up_write(&oldmm
->mmap_sem
);
717 #define mm_alloc_pgd(mm) (0)
718 #define mm_free_pgd(mm)
719 #endif /* CONFIG_MMU */
721 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
723 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
724 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
726 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
728 static int __init
coredump_filter_setup(char *s
)
730 default_dump_filter
=
731 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
732 MMF_DUMP_FILTER_MASK
;
736 __setup("coredump_filter=", coredump_filter_setup
);
738 #include <linux/init_task.h>
740 static void mm_init_aio(struct mm_struct
*mm
)
743 spin_lock_init(&mm
->ioctx_lock
);
744 mm
->ioctx_table
= NULL
;
748 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
755 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
,
756 struct user_namespace
*user_ns
)
760 mm
->vmacache_seqnum
= 0;
761 atomic_set(&mm
->mm_users
, 1);
762 atomic_set(&mm
->mm_count
, 1);
763 init_rwsem(&mm
->mmap_sem
);
764 INIT_LIST_HEAD(&mm
->mmlist
);
765 mm
->core_state
= NULL
;
766 atomic_long_set(&mm
->nr_ptes
, 0);
771 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
772 spin_lock_init(&mm
->page_table_lock
);
775 mm_init_owner(mm
, p
);
776 mmu_notifier_mm_init(mm
);
777 clear_tlb_flush_pending(mm
);
778 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
779 mm
->pmd_huge_pte
= NULL
;
783 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
784 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
786 mm
->flags
= default_dump_filter
;
790 if (mm_alloc_pgd(mm
))
793 if (init_new_context(p
, mm
))
796 mm
->user_ns
= get_user_ns(user_ns
);
806 static void check_mm(struct mm_struct
*mm
)
810 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
811 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
814 printk(KERN_ALERT
"BUG: Bad rss-counter state "
815 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
818 if (atomic_long_read(&mm
->nr_ptes
))
819 pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
820 atomic_long_read(&mm
->nr_ptes
));
822 pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
825 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
826 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
831 * Allocate and initialize an mm_struct.
833 struct mm_struct
*mm_alloc(void)
835 struct mm_struct
*mm
;
841 memset(mm
, 0, sizeof(*mm
));
842 return mm_init(mm
, current
, current_user_ns());
846 * Called when the last reference to the mm
847 * is dropped: either by a lazy thread or by
848 * mmput. Free the page directory and the mm.
850 void __mmdrop(struct mm_struct
*mm
)
852 BUG_ON(mm
== &init_mm
);
855 mmu_notifier_mm_destroy(mm
);
857 put_user_ns(mm
->user_ns
);
860 EXPORT_SYMBOL_GPL(__mmdrop
);
862 static inline void __mmput(struct mm_struct
*mm
)
864 VM_BUG_ON(atomic_read(&mm
->mm_users
));
866 uprobe_clear_state(mm
);
869 khugepaged_exit(mm
); /* must run before exit_mmap */
871 mm_put_huge_zero_page(mm
);
872 set_mm_exe_file(mm
, NULL
);
873 if (!list_empty(&mm
->mmlist
)) {
874 spin_lock(&mmlist_lock
);
875 list_del(&mm
->mmlist
);
876 spin_unlock(&mmlist_lock
);
879 module_put(mm
->binfmt
->module
);
880 set_bit(MMF_OOM_SKIP
, &mm
->flags
);
885 * Decrement the use count and release all resources for an mm.
887 void mmput(struct mm_struct
*mm
)
891 if (atomic_dec_and_test(&mm
->mm_users
))
894 EXPORT_SYMBOL_GPL(mmput
);
897 static void mmput_async_fn(struct work_struct
*work
)
899 struct mm_struct
*mm
= container_of(work
, struct mm_struct
, async_put_work
);
903 void mmput_async(struct mm_struct
*mm
)
905 if (atomic_dec_and_test(&mm
->mm_users
)) {
906 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
907 schedule_work(&mm
->async_put_work
);
913 * set_mm_exe_file - change a reference to the mm's executable file
915 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
917 * Main users are mmput() and sys_execve(). Callers prevent concurrent
918 * invocations: in mmput() nobody alive left, in execve task is single
919 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
920 * mm->exe_file, but does so without using set_mm_exe_file() in order
921 * to do avoid the need for any locks.
923 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
925 struct file
*old_exe_file
;
928 * It is safe to dereference the exe_file without RCU as
929 * this function is only called if nobody else can access
930 * this mm -- see comment above for justification.
932 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
935 get_file(new_exe_file
);
936 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
942 * get_mm_exe_file - acquire a reference to the mm's executable file
944 * Returns %NULL if mm has no associated executable file.
945 * User must release file via fput().
947 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
949 struct file
*exe_file
;
952 exe_file
= rcu_dereference(mm
->exe_file
);
953 if (exe_file
&& !get_file_rcu(exe_file
))
958 EXPORT_SYMBOL(get_mm_exe_file
);
961 * get_task_exe_file - acquire a reference to the task's executable file
963 * Returns %NULL if task's mm (if any) has no associated executable file or
964 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
965 * User must release file via fput().
967 struct file
*get_task_exe_file(struct task_struct
*task
)
969 struct file
*exe_file
= NULL
;
970 struct mm_struct
*mm
;
975 if (!(task
->flags
& PF_KTHREAD
))
976 exe_file
= get_mm_exe_file(mm
);
981 EXPORT_SYMBOL(get_task_exe_file
);
984 * get_task_mm - acquire a reference to the task's mm
986 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
987 * this kernel workthread has transiently adopted a user mm with use_mm,
988 * to do its AIO) is not set and if so returns a reference to it, after
989 * bumping up the use count. User must release the mm via mmput()
990 * after use. Typically used by /proc and ptrace.
992 struct mm_struct
*get_task_mm(struct task_struct
*task
)
994 struct mm_struct
*mm
;
999 if (task
->flags
& PF_KTHREAD
)
1002 atomic_inc(&mm
->mm_users
);
1007 EXPORT_SYMBOL_GPL(get_task_mm
);
1009 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1011 struct mm_struct
*mm
;
1014 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
1016 return ERR_PTR(err
);
1018 mm
= get_task_mm(task
);
1019 if (mm
&& mm
!= current
->mm
&&
1020 !ptrace_may_access(task
, mode
)) {
1022 mm
= ERR_PTR(-EACCES
);
1024 mutex_unlock(&task
->signal
->cred_guard_mutex
);
1029 static void complete_vfork_done(struct task_struct
*tsk
)
1031 struct completion
*vfork
;
1034 vfork
= tsk
->vfork_done
;
1035 if (likely(vfork
)) {
1036 tsk
->vfork_done
= NULL
;
1042 static int wait_for_vfork_done(struct task_struct
*child
,
1043 struct completion
*vfork
)
1047 freezer_do_not_count();
1048 killed
= wait_for_completion_killable(vfork
);
1053 child
->vfork_done
= NULL
;
1057 put_task_struct(child
);
1061 /* Please note the differences between mmput and mm_release.
1062 * mmput is called whenever we stop holding onto a mm_struct,
1063 * error success whatever.
1065 * mm_release is called after a mm_struct has been removed
1066 * from the current process.
1068 * This difference is important for error handling, when we
1069 * only half set up a mm_struct for a new process and need to restore
1070 * the old one. Because we mmput the new mm_struct before
1071 * restoring the old one. . .
1072 * Eric Biederman 10 January 1998
1074 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1076 /* Get rid of any futexes when releasing the mm */
1078 if (unlikely(tsk
->robust_list
)) {
1079 exit_robust_list(tsk
);
1080 tsk
->robust_list
= NULL
;
1082 #ifdef CONFIG_COMPAT
1083 if (unlikely(tsk
->compat_robust_list
)) {
1084 compat_exit_robust_list(tsk
);
1085 tsk
->compat_robust_list
= NULL
;
1088 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1089 exit_pi_state_list(tsk
);
1092 uprobe_free_utask(tsk
);
1094 /* Get rid of any cached register state */
1095 deactivate_mm(tsk
, mm
);
1098 * Signal userspace if we're not exiting with a core dump
1099 * because we want to leave the value intact for debugging
1102 if (tsk
->clear_child_tid
) {
1103 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1104 atomic_read(&mm
->mm_users
) > 1) {
1106 * We don't check the error code - if userspace has
1107 * not set up a proper pointer then tough luck.
1109 put_user(0, tsk
->clear_child_tid
);
1110 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1113 tsk
->clear_child_tid
= NULL
;
1117 * All done, finally we can wake up parent and return this mm to him.
1118 * Also kthread_stop() uses this completion for synchronization.
1120 if (tsk
->vfork_done
)
1121 complete_vfork_done(tsk
);
1125 * Allocate a new mm structure and copy contents from the
1126 * mm structure of the passed in task structure.
1128 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
1130 struct mm_struct
*mm
, *oldmm
= current
->mm
;
1137 memcpy(mm
, oldmm
, sizeof(*mm
));
1139 if (!mm_init(mm
, tsk
, mm
->user_ns
))
1142 err
= dup_mmap(mm
, oldmm
);
1146 mm
->hiwater_rss
= get_mm_rss(mm
);
1147 mm
->hiwater_vm
= mm
->total_vm
;
1149 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1155 /* don't put binfmt in mmput, we haven't got module yet */
1163 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1165 struct mm_struct
*mm
, *oldmm
;
1168 tsk
->min_flt
= tsk
->maj_flt
= 0;
1169 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1170 #ifdef CONFIG_DETECT_HUNG_TASK
1171 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1175 tsk
->active_mm
= NULL
;
1178 * Are we cloning a kernel thread?
1180 * We need to steal a active VM for that..
1182 oldmm
= current
->mm
;
1186 /* initialize the new vmacache entries */
1187 vmacache_flush(tsk
);
1189 if (clone_flags
& CLONE_VM
) {
1190 atomic_inc(&oldmm
->mm_users
);
1202 tsk
->active_mm
= mm
;
1209 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1211 struct fs_struct
*fs
= current
->fs
;
1212 if (clone_flags
& CLONE_FS
) {
1213 /* tsk->fs is already what we want */
1214 spin_lock(&fs
->lock
);
1216 spin_unlock(&fs
->lock
);
1220 spin_unlock(&fs
->lock
);
1223 tsk
->fs
= copy_fs_struct(fs
);
1229 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1231 struct files_struct
*oldf
, *newf
;
1235 * A background process may not have any files ...
1237 oldf
= current
->files
;
1241 if (clone_flags
& CLONE_FILES
) {
1242 atomic_inc(&oldf
->count
);
1246 newf
= dup_fd(oldf
, &error
);
1256 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1259 struct io_context
*ioc
= current
->io_context
;
1260 struct io_context
*new_ioc
;
1265 * Share io context with parent, if CLONE_IO is set
1267 if (clone_flags
& CLONE_IO
) {
1269 tsk
->io_context
= ioc
;
1270 } else if (ioprio_valid(ioc
->ioprio
)) {
1271 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1272 if (unlikely(!new_ioc
))
1275 new_ioc
->ioprio
= ioc
->ioprio
;
1276 put_io_context(new_ioc
);
1282 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1284 struct sighand_struct
*sig
;
1286 if (clone_flags
& CLONE_SIGHAND
) {
1287 atomic_inc(¤t
->sighand
->count
);
1290 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1291 rcu_assign_pointer(tsk
->sighand
, sig
);
1295 atomic_set(&sig
->count
, 1);
1296 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1300 void __cleanup_sighand(struct sighand_struct
*sighand
)
1302 if (atomic_dec_and_test(&sighand
->count
)) {
1303 signalfd_cleanup(sighand
);
1305 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
1306 * without an RCU grace period, see __lock_task_sighand().
1308 kmem_cache_free(sighand_cachep
, sighand
);
1313 * Initialize POSIX timer handling for a thread group.
1315 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1317 unsigned long cpu_limit
;
1319 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1320 if (cpu_limit
!= RLIM_INFINITY
) {
1321 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1322 sig
->cputimer
.running
= true;
1325 /* The timer lists. */
1326 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1327 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1328 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1331 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1333 struct signal_struct
*sig
;
1335 if (clone_flags
& CLONE_THREAD
)
1338 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1343 sig
->nr_threads
= 1;
1344 atomic_set(&sig
->live
, 1);
1345 atomic_set(&sig
->sigcnt
, 1);
1347 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1348 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1349 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1351 init_waitqueue_head(&sig
->wait_chldexit
);
1352 sig
->curr_target
= tsk
;
1353 init_sigpending(&sig
->shared_pending
);
1354 INIT_LIST_HEAD(&sig
->posix_timers
);
1355 seqlock_init(&sig
->stats_lock
);
1356 prev_cputime_init(&sig
->prev_cputime
);
1358 #ifdef CONFIG_POSIX_TIMERS
1359 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1360 sig
->real_timer
.function
= it_real_fn
;
1363 task_lock(current
->group_leader
);
1364 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1365 task_unlock(current
->group_leader
);
1367 posix_cpu_timers_init_group(sig
);
1369 tty_audit_fork(sig
);
1370 sched_autogroup_fork(sig
);
1372 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1373 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1375 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1376 current
->signal
->is_child_subreaper
;
1378 mutex_init(&sig
->cred_guard_mutex
);
1383 static void copy_seccomp(struct task_struct
*p
)
1385 #ifdef CONFIG_SECCOMP
1387 * Must be called with sighand->lock held, which is common to
1388 * all threads in the group. Holding cred_guard_mutex is not
1389 * needed because this new task is not yet running and cannot
1392 assert_spin_locked(¤t
->sighand
->siglock
);
1394 /* Ref-count the new filter user, and assign it. */
1395 get_seccomp_filter(current
);
1396 p
->seccomp
= current
->seccomp
;
1399 * Explicitly enable no_new_privs here in case it got set
1400 * between the task_struct being duplicated and holding the
1401 * sighand lock. The seccomp state and nnp must be in sync.
1403 if (task_no_new_privs(current
))
1404 task_set_no_new_privs(p
);
1407 * If the parent gained a seccomp mode after copying thread
1408 * flags and between before we held the sighand lock, we have
1409 * to manually enable the seccomp thread flag here.
1411 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1412 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1416 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1418 current
->clear_child_tid
= tidptr
;
1420 return task_pid_vnr(current
);
1423 static void rt_mutex_init_task(struct task_struct
*p
)
1425 raw_spin_lock_init(&p
->pi_lock
);
1426 #ifdef CONFIG_RT_MUTEXES
1427 p
->pi_waiters
= RB_ROOT
;
1428 p
->pi_waiters_leftmost
= NULL
;
1429 p
->pi_blocked_on
= NULL
;
1434 * Initialize POSIX timer handling for a single task.
1436 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1438 tsk
->cputime_expires
.prof_exp
= 0;
1439 tsk
->cputime_expires
.virt_exp
= 0;
1440 tsk
->cputime_expires
.sched_exp
= 0;
1441 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1442 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1443 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1447 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1449 task
->pids
[type
].pid
= pid
;
1453 * This creates a new process as a copy of the old one,
1454 * but does not actually start it yet.
1456 * It copies the registers, and all the appropriate
1457 * parts of the process environment (as per the clone
1458 * flags). The actual kick-off is left to the caller.
1460 static __latent_entropy
struct task_struct
*copy_process(
1461 unsigned long clone_flags
,
1462 unsigned long stack_start
,
1463 unsigned long stack_size
,
1464 int __user
*child_tidptr
,
1471 struct task_struct
*p
;
1473 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1474 return ERR_PTR(-EINVAL
);
1476 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1477 return ERR_PTR(-EINVAL
);
1479 if ((clone_flags
& CLONE_NEWUSER
) && !unprivileged_userns_clone
)
1480 if (!capable(CAP_SYS_ADMIN
))
1481 return ERR_PTR(-EPERM
);
1484 * Thread groups must share signals as well, and detached threads
1485 * can only be started up within the thread group.
1487 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1488 return ERR_PTR(-EINVAL
);
1491 * Shared signal handlers imply shared VM. By way of the above,
1492 * thread groups also imply shared VM. Blocking this case allows
1493 * for various simplifications in other code.
1495 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1496 return ERR_PTR(-EINVAL
);
1499 * Siblings of global init remain as zombies on exit since they are
1500 * not reaped by their parent (swapper). To solve this and to avoid
1501 * multi-rooted process trees, prevent global and container-inits
1502 * from creating siblings.
1504 if ((clone_flags
& CLONE_PARENT
) &&
1505 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1506 return ERR_PTR(-EINVAL
);
1509 * If the new process will be in a different pid or user namespace
1510 * do not allow it to share a thread group with the forking task.
1512 if (clone_flags
& CLONE_THREAD
) {
1513 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1514 (task_active_pid_ns(current
) !=
1515 current
->nsproxy
->pid_ns_for_children
))
1516 return ERR_PTR(-EINVAL
);
1519 retval
= security_task_create(clone_flags
);
1524 p
= dup_task_struct(current
, node
);
1528 ftrace_graph_init_task(p
);
1530 rt_mutex_init_task(p
);
1532 #ifdef CONFIG_PROVE_LOCKING
1533 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1534 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1537 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1538 task_rlimit(p
, RLIMIT_NPROC
)) {
1539 if (p
->real_cred
->user
!= INIT_USER
&&
1540 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1543 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1545 retval
= copy_creds(p
, clone_flags
);
1550 * If multiple threads are within copy_process(), then this check
1551 * triggers too late. This doesn't hurt, the check is only there
1552 * to stop root fork bombs.
1555 if (nr_threads
>= max_threads
)
1556 goto bad_fork_cleanup_count
;
1558 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1559 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
| PF_IDLE
);
1560 p
->flags
|= PF_FORKNOEXEC
;
1561 INIT_LIST_HEAD(&p
->children
);
1562 INIT_LIST_HEAD(&p
->sibling
);
1563 rcu_copy_process(p
);
1564 p
->vfork_done
= NULL
;
1565 spin_lock_init(&p
->alloc_lock
);
1567 init_sigpending(&p
->pending
);
1569 p
->utime
= p
->stime
= p
->gtime
= 0;
1570 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1571 p
->utimescaled
= p
->stimescaled
= 0;
1573 prev_cputime_init(&p
->prev_cputime
);
1575 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1576 seqcount_init(&p
->vtime_seqcount
);
1578 p
->vtime_snap_whence
= VTIME_INACTIVE
;
1581 #if defined(SPLIT_RSS_COUNTING)
1582 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1585 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1587 task_io_accounting_init(&p
->ioac
);
1588 acct_clear_integrals(p
);
1590 posix_cpu_timers_init(p
);
1592 p
->start_time
= ktime_get_ns();
1593 p
->real_start_time
= ktime_get_boot_ns();
1594 p
->io_context
= NULL
;
1595 p
->audit_context
= NULL
;
1598 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1599 if (IS_ERR(p
->mempolicy
)) {
1600 retval
= PTR_ERR(p
->mempolicy
);
1601 p
->mempolicy
= NULL
;
1602 goto bad_fork_cleanup_threadgroup_lock
;
1605 #ifdef CONFIG_CPUSETS
1606 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1607 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1608 seqcount_init(&p
->mems_allowed_seq
);
1610 #ifdef CONFIG_TRACE_IRQFLAGS
1612 p
->hardirqs_enabled
= 0;
1613 p
->hardirq_enable_ip
= 0;
1614 p
->hardirq_enable_event
= 0;
1615 p
->hardirq_disable_ip
= _THIS_IP_
;
1616 p
->hardirq_disable_event
= 0;
1617 p
->softirqs_enabled
= 1;
1618 p
->softirq_enable_ip
= _THIS_IP_
;
1619 p
->softirq_enable_event
= 0;
1620 p
->softirq_disable_ip
= 0;
1621 p
->softirq_disable_event
= 0;
1622 p
->hardirq_context
= 0;
1623 p
->softirq_context
= 0;
1626 p
->pagefault_disabled
= 0;
1628 #ifdef CONFIG_LOCKDEP
1629 p
->lockdep_depth
= 0; /* no locks held yet */
1630 p
->curr_chain_key
= 0;
1631 p
->lockdep_recursion
= 0;
1634 #ifdef CONFIG_DEBUG_MUTEXES
1635 p
->blocked_on
= NULL
; /* not blocked yet */
1637 #ifdef CONFIG_BCACHE
1638 p
->sequential_io
= 0;
1639 p
->sequential_io_avg
= 0;
1642 /* Perform scheduler related setup. Assign this task to a CPU. */
1643 retval
= sched_fork(clone_flags
, p
);
1645 goto bad_fork_cleanup_policy
;
1647 retval
= perf_event_init_task(p
);
1649 goto bad_fork_cleanup_policy
;
1650 retval
= audit_alloc(p
);
1652 goto bad_fork_cleanup_perf
;
1653 /* copy all the process information */
1655 retval
= copy_semundo(clone_flags
, p
);
1657 goto bad_fork_cleanup_audit
;
1658 retval
= copy_files(clone_flags
, p
);
1660 goto bad_fork_cleanup_semundo
;
1661 retval
= copy_fs(clone_flags
, p
);
1663 goto bad_fork_cleanup_files
;
1664 retval
= copy_sighand(clone_flags
, p
);
1666 goto bad_fork_cleanup_fs
;
1667 retval
= copy_signal(clone_flags
, p
);
1669 goto bad_fork_cleanup_sighand
;
1670 retval
= copy_mm(clone_flags
, p
);
1672 goto bad_fork_cleanup_signal
;
1673 retval
= copy_namespaces(clone_flags
, p
);
1675 goto bad_fork_cleanup_mm
;
1676 retval
= copy_io(clone_flags
, p
);
1678 goto bad_fork_cleanup_namespaces
;
1679 retval
= copy_thread_tls(clone_flags
, stack_start
, stack_size
, p
, tls
);
1681 goto bad_fork_cleanup_io
;
1683 if (pid
!= &init_struct_pid
) {
1684 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1686 retval
= PTR_ERR(pid
);
1687 goto bad_fork_cleanup_thread
;
1691 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1693 * Clear TID on mm_release()?
1695 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1700 p
->robust_list
= NULL
;
1701 #ifdef CONFIG_COMPAT
1702 p
->compat_robust_list
= NULL
;
1704 INIT_LIST_HEAD(&p
->pi_state_list
);
1705 p
->pi_state_cache
= NULL
;
1708 * sigaltstack should be cleared when sharing the same VM
1710 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1714 * Syscall tracing and stepping should be turned off in the
1715 * child regardless of CLONE_PTRACE.
1717 user_disable_single_step(p
);
1718 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1719 #ifdef TIF_SYSCALL_EMU
1720 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1722 clear_all_latency_tracing(p
);
1724 /* ok, now we should be set up.. */
1725 p
->pid
= pid_nr(pid
);
1726 if (clone_flags
& CLONE_THREAD
) {
1727 p
->exit_signal
= -1;
1728 p
->group_leader
= current
->group_leader
;
1729 p
->tgid
= current
->tgid
;
1731 if (clone_flags
& CLONE_PARENT
)
1732 p
->exit_signal
= current
->group_leader
->exit_signal
;
1734 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1735 p
->group_leader
= p
;
1740 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1741 p
->dirty_paused_when
= 0;
1743 p
->pdeath_signal
= 0;
1744 INIT_LIST_HEAD(&p
->thread_group
);
1745 p
->task_works
= NULL
;
1747 threadgroup_change_begin(current
);
1749 * Ensure that the cgroup subsystem policies allow the new process to be
1750 * forked. It should be noted the the new process's css_set can be changed
1751 * between here and cgroup_post_fork() if an organisation operation is in
1754 retval
= cgroup_can_fork(p
);
1756 goto bad_fork_free_pid
;
1759 * Make it visible to the rest of the system, but dont wake it up yet.
1760 * Need tasklist lock for parent etc handling!
1762 write_lock_irq(&tasklist_lock
);
1764 /* CLONE_PARENT re-uses the old parent */
1765 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1766 p
->real_parent
= current
->real_parent
;
1767 p
->parent_exec_id
= current
->parent_exec_id
;
1769 p
->real_parent
= current
;
1770 p
->parent_exec_id
= current
->self_exec_id
;
1773 spin_lock(¤t
->sighand
->siglock
);
1776 * Copy seccomp details explicitly here, in case they were changed
1777 * before holding sighand lock.
1782 * Process group and session signals need to be delivered to just the
1783 * parent before the fork or both the parent and the child after the
1784 * fork. Restart if a signal comes in before we add the new process to
1785 * it's process group.
1786 * A fatal signal pending means that current will exit, so the new
1787 * thread can't slip out of an OOM kill (or normal SIGKILL).
1789 recalc_sigpending();
1790 if (signal_pending(current
)) {
1791 spin_unlock(¤t
->sighand
->siglock
);
1792 write_unlock_irq(&tasklist_lock
);
1793 retval
= -ERESTARTNOINTR
;
1794 goto bad_fork_cancel_cgroup
;
1797 if (likely(p
->pid
)) {
1798 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1800 init_task_pid(p
, PIDTYPE_PID
, pid
);
1801 if (thread_group_leader(p
)) {
1802 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1803 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1805 if (is_child_reaper(pid
)) {
1806 ns_of_pid(pid
)->child_reaper
= p
;
1807 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1810 p
->signal
->leader_pid
= pid
;
1811 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1812 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1813 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1814 attach_pid(p
, PIDTYPE_PGID
);
1815 attach_pid(p
, PIDTYPE_SID
);
1816 __this_cpu_inc(process_counts
);
1818 current
->signal
->nr_threads
++;
1819 atomic_inc(¤t
->signal
->live
);
1820 atomic_inc(¤t
->signal
->sigcnt
);
1821 list_add_tail_rcu(&p
->thread_group
,
1822 &p
->group_leader
->thread_group
);
1823 list_add_tail_rcu(&p
->thread_node
,
1824 &p
->signal
->thread_head
);
1826 attach_pid(p
, PIDTYPE_PID
);
1831 spin_unlock(¤t
->sighand
->siglock
);
1832 syscall_tracepoint_update(p
);
1833 write_unlock_irq(&tasklist_lock
);
1835 proc_fork_connector(p
);
1836 cgroup_post_fork(p
);
1837 threadgroup_change_end(current
);
1840 trace_task_newtask(p
, clone_flags
);
1841 uprobe_copy_process(p
, clone_flags
);
1845 bad_fork_cancel_cgroup
:
1846 cgroup_cancel_fork(p
);
1848 threadgroup_change_end(current
);
1849 if (pid
!= &init_struct_pid
)
1851 bad_fork_cleanup_thread
:
1853 bad_fork_cleanup_io
:
1856 bad_fork_cleanup_namespaces
:
1857 exit_task_namespaces(p
);
1858 bad_fork_cleanup_mm
:
1861 bad_fork_cleanup_signal
:
1862 if (!(clone_flags
& CLONE_THREAD
))
1863 free_signal_struct(p
->signal
);
1864 bad_fork_cleanup_sighand
:
1865 __cleanup_sighand(p
->sighand
);
1866 bad_fork_cleanup_fs
:
1867 exit_fs(p
); /* blocking */
1868 bad_fork_cleanup_files
:
1869 exit_files(p
); /* blocking */
1870 bad_fork_cleanup_semundo
:
1872 bad_fork_cleanup_audit
:
1874 bad_fork_cleanup_perf
:
1875 perf_event_free_task(p
);
1876 bad_fork_cleanup_policy
:
1878 mpol_put(p
->mempolicy
);
1879 bad_fork_cleanup_threadgroup_lock
:
1881 delayacct_tsk_free(p
);
1882 bad_fork_cleanup_count
:
1883 atomic_dec(&p
->cred
->user
->processes
);
1886 p
->state
= TASK_DEAD
;
1890 return ERR_PTR(retval
);
1893 static inline void init_idle_pids(struct pid_link
*links
)
1897 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1898 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1899 links
[type
].pid
= &init_struct_pid
;
1903 struct task_struct
*fork_idle(int cpu
)
1905 struct task_struct
*task
;
1906 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0, 0,
1908 if (!IS_ERR(task
)) {
1909 init_idle_pids(task
->pids
);
1910 init_idle(task
, cpu
);
1917 * Ok, this is the main fork-routine.
1919 * It copies the process, and if successful kick-starts
1920 * it and waits for it to finish using the VM if required.
1922 long _do_fork(unsigned long clone_flags
,
1923 unsigned long stack_start
,
1924 unsigned long stack_size
,
1925 int __user
*parent_tidptr
,
1926 int __user
*child_tidptr
,
1929 struct task_struct
*p
;
1934 * Determine whether and which event to report to ptracer. When
1935 * called from kernel_thread or CLONE_UNTRACED is explicitly
1936 * requested, no event is reported; otherwise, report if the event
1937 * for the type of forking is enabled.
1939 if (!(clone_flags
& CLONE_UNTRACED
)) {
1940 if (clone_flags
& CLONE_VFORK
)
1941 trace
= PTRACE_EVENT_VFORK
;
1942 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1943 trace
= PTRACE_EVENT_CLONE
;
1945 trace
= PTRACE_EVENT_FORK
;
1947 if (likely(!ptrace_event_enabled(current
, trace
)))
1951 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1952 child_tidptr
, NULL
, trace
, tls
, NUMA_NO_NODE
);
1953 add_latent_entropy();
1955 * Do this prior waking up the new thread - the thread pointer
1956 * might get invalid after that point, if the thread exits quickly.
1959 struct completion vfork
;
1962 trace_sched_process_fork(current
, p
);
1964 pid
= get_task_pid(p
, PIDTYPE_PID
);
1967 if (clone_flags
& CLONE_PARENT_SETTID
)
1968 put_user(nr
, parent_tidptr
);
1970 if (clone_flags
& CLONE_VFORK
) {
1971 p
->vfork_done
= &vfork
;
1972 init_completion(&vfork
);
1976 wake_up_new_task(p
);
1978 /* forking complete and child started to run, tell ptracer */
1979 if (unlikely(trace
))
1980 ptrace_event_pid(trace
, pid
);
1982 if (clone_flags
& CLONE_VFORK
) {
1983 if (!wait_for_vfork_done(p
, &vfork
))
1984 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
1994 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
1995 /* For compatibility with architectures that call do_fork directly rather than
1996 * using the syscall entry points below. */
1997 long do_fork(unsigned long clone_flags
,
1998 unsigned long stack_start
,
1999 unsigned long stack_size
,
2000 int __user
*parent_tidptr
,
2001 int __user
*child_tidptr
)
2003 return _do_fork(clone_flags
, stack_start
, stack_size
,
2004 parent_tidptr
, child_tidptr
, 0);
2009 * Create a kernel thread.
2011 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
2013 return _do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
2014 (unsigned long)arg
, NULL
, NULL
, 0);
2017 #ifdef __ARCH_WANT_SYS_FORK
2018 SYSCALL_DEFINE0(fork
)
2021 return _do_fork(SIGCHLD
, 0, 0, NULL
, NULL
, 0);
2023 /* can not support in nommu mode */
2029 #ifdef __ARCH_WANT_SYS_VFORK
2030 SYSCALL_DEFINE0(vfork
)
2032 return _do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
2037 #ifdef __ARCH_WANT_SYS_CLONE
2038 #ifdef CONFIG_CLONE_BACKWARDS
2039 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2040 int __user
*, parent_tidptr
,
2042 int __user
*, child_tidptr
)
2043 #elif defined(CONFIG_CLONE_BACKWARDS2)
2044 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2045 int __user
*, parent_tidptr
,
2046 int __user
*, child_tidptr
,
2048 #elif defined(CONFIG_CLONE_BACKWARDS3)
2049 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2051 int __user
*, parent_tidptr
,
2052 int __user
*, child_tidptr
,
2055 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2056 int __user
*, parent_tidptr
,
2057 int __user
*, child_tidptr
,
2061 return _do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
, tls
);
2065 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2066 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2069 static void sighand_ctor(void *data
)
2071 struct sighand_struct
*sighand
= data
;
2073 spin_lock_init(&sighand
->siglock
);
2074 init_waitqueue_head(&sighand
->signalfd_wqh
);
2077 void __init
proc_caches_init(void)
2079 sighand_cachep
= kmem_cache_create("sighand_cache",
2080 sizeof(struct sighand_struct
), 0,
2081 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
2082 SLAB_NOTRACK
|SLAB_ACCOUNT
, sighand_ctor
);
2083 signal_cachep
= kmem_cache_create("signal_cache",
2084 sizeof(struct signal_struct
), 0,
2085 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2087 files_cachep
= kmem_cache_create("files_cache",
2088 sizeof(struct files_struct
), 0,
2089 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2091 fs_cachep
= kmem_cache_create("fs_cache",
2092 sizeof(struct fs_struct
), 0,
2093 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2096 * FIXME! The "sizeof(struct mm_struct)" currently includes the
2097 * whole struct cpumask for the OFFSTACK case. We could change
2098 * this to *only* allocate as much of it as required by the
2099 * maximum number of CPU's we can ever have. The cpumask_allocation
2100 * is at the end of the structure, exactly for that reason.
2102 mm_cachep
= kmem_cache_create("mm_struct",
2103 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
2104 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2106 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2108 nsproxy_cache_init();
2112 * Check constraints on flags passed to the unshare system call.
2114 static int check_unshare_flags(unsigned long unshare_flags
)
2116 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2117 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2118 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2119 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
))
2122 * Not implemented, but pretend it works if there is nothing
2123 * to unshare. Note that unsharing the address space or the
2124 * signal handlers also need to unshare the signal queues (aka
2127 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2128 if (!thread_group_empty(current
))
2131 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2132 if (atomic_read(¤t
->sighand
->count
) > 1)
2135 if (unshare_flags
& CLONE_VM
) {
2136 if (!current_is_single_threaded())
2144 * Unshare the filesystem structure if it is being shared
2146 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2148 struct fs_struct
*fs
= current
->fs
;
2150 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2153 /* don't need lock here; in the worst case we'll do useless copy */
2157 *new_fsp
= copy_fs_struct(fs
);
2165 * Unshare file descriptor table if it is being shared
2167 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2169 struct files_struct
*fd
= current
->files
;
2172 if ((unshare_flags
& CLONE_FILES
) &&
2173 (fd
&& atomic_read(&fd
->count
) > 1)) {
2174 *new_fdp
= dup_fd(fd
, &error
);
2183 * unshare allows a process to 'unshare' part of the process
2184 * context which was originally shared using clone. copy_*
2185 * functions used by do_fork() cannot be used here directly
2186 * because they modify an inactive task_struct that is being
2187 * constructed. Here we are modifying the current, active,
2190 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
2192 struct fs_struct
*fs
, *new_fs
= NULL
;
2193 struct files_struct
*fd
, *new_fd
= NULL
;
2194 struct cred
*new_cred
= NULL
;
2195 struct nsproxy
*new_nsproxy
= NULL
;
2200 * If unsharing a user namespace must also unshare the thread group
2201 * and unshare the filesystem root and working directories.
2203 if (unshare_flags
& CLONE_NEWUSER
)
2204 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2206 * If unsharing vm, must also unshare signal handlers.
2208 if (unshare_flags
& CLONE_VM
)
2209 unshare_flags
|= CLONE_SIGHAND
;
2211 * If unsharing a signal handlers, must also unshare the signal queues.
2213 if (unshare_flags
& CLONE_SIGHAND
)
2214 unshare_flags
|= CLONE_THREAD
;
2216 * If unsharing namespace, must also unshare filesystem information.
2218 if (unshare_flags
& CLONE_NEWNS
)
2219 unshare_flags
|= CLONE_FS
;
2221 if ((unshare_flags
& CLONE_NEWUSER
) && !unprivileged_userns_clone
) {
2223 if (!capable(CAP_SYS_ADMIN
))
2224 goto bad_unshare_out
;
2227 err
= check_unshare_flags(unshare_flags
);
2229 goto bad_unshare_out
;
2231 * CLONE_NEWIPC must also detach from the undolist: after switching
2232 * to a new ipc namespace, the semaphore arrays from the old
2233 * namespace are unreachable.
2235 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2237 err
= unshare_fs(unshare_flags
, &new_fs
);
2239 goto bad_unshare_out
;
2240 err
= unshare_fd(unshare_flags
, &new_fd
);
2242 goto bad_unshare_cleanup_fs
;
2243 err
= unshare_userns(unshare_flags
, &new_cred
);
2245 goto bad_unshare_cleanup_fd
;
2246 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2249 goto bad_unshare_cleanup_cred
;
2251 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2254 * CLONE_SYSVSEM is equivalent to sys_exit().
2258 if (unshare_flags
& CLONE_NEWIPC
) {
2259 /* Orphan segments in old ns (see sem above). */
2261 shm_init_task(current
);
2265 switch_task_namespaces(current
, new_nsproxy
);
2271 spin_lock(&fs
->lock
);
2272 current
->fs
= new_fs
;
2277 spin_unlock(&fs
->lock
);
2281 fd
= current
->files
;
2282 current
->files
= new_fd
;
2286 task_unlock(current
);
2289 /* Install the new user namespace */
2290 commit_creds(new_cred
);
2295 bad_unshare_cleanup_cred
:
2298 bad_unshare_cleanup_fd
:
2300 put_files_struct(new_fd
);
2302 bad_unshare_cleanup_fs
:
2304 free_fs_struct(new_fs
);
2311 * Helper to unshare the files of the current task.
2312 * We don't want to expose copy_files internals to
2313 * the exec layer of the kernel.
2316 int unshare_files(struct files_struct
**displaced
)
2318 struct task_struct
*task
= current
;
2319 struct files_struct
*copy
= NULL
;
2322 error
= unshare_fd(CLONE_FILES
, ©
);
2323 if (error
|| !copy
) {
2327 *displaced
= task
->files
;
2334 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2335 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2339 int threads
= max_threads
;
2340 int min
= MIN_THREADS
;
2341 int max
= MAX_THREADS
;
2348 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2352 set_max_threads(threads
);