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 <asm/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>
93 * Minimum number of threads to boot the kernel
95 #define MIN_THREADS 20
98 * Maximum number of threads
100 #define MAX_THREADS FUTEX_TID_MASK
103 * Protected counters by write_lock_irq(&tasklist_lock)
105 unsigned long total_forks
; /* Handle normal Linux uptimes. */
106 int nr_threads
; /* The idle threads do not count.. */
108 int max_threads
; /* tunable limit on nr_threads */
110 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
112 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
114 #ifdef CONFIG_PROVE_RCU
115 int lockdep_tasklist_lock_is_held(void)
117 return lockdep_is_held(&tasklist_lock
);
119 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
120 #endif /* #ifdef CONFIG_PROVE_RCU */
122 int nr_processes(void)
127 for_each_possible_cpu(cpu
)
128 total
+= per_cpu(process_counts
, cpu
);
133 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
137 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
138 static struct kmem_cache
*task_struct_cachep
;
140 static inline struct task_struct
*alloc_task_struct_node(int node
)
142 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
145 static inline void free_task_struct(struct task_struct
*tsk
)
147 kmem_cache_free(task_struct_cachep
, tsk
);
151 void __weak
arch_release_thread_stack(unsigned long *stack
)
155 #ifndef CONFIG_ARCH_THREAD_STACK_ALLOCATOR
158 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
159 * kmemcache based allocator.
161 # if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
163 #ifdef CONFIG_VMAP_STACK
165 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
166 * flush. Try to minimize the number of calls by caching stacks.
168 #define NR_CACHED_STACKS 2
169 static DEFINE_PER_CPU(struct vm_struct
*, cached_stacks
[NR_CACHED_STACKS
]);
172 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
, int node
)
174 #ifdef CONFIG_VMAP_STACK
179 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
180 struct vm_struct
*s
= this_cpu_read(cached_stacks
[i
]);
184 this_cpu_write(cached_stacks
[i
], NULL
);
186 tsk
->stack_vm_area
= s
;
192 stack
= __vmalloc_node_range(THREAD_SIZE
, THREAD_SIZE
,
193 VMALLOC_START
, VMALLOC_END
,
194 THREADINFO_GFP
| __GFP_HIGHMEM
,
196 0, node
, __builtin_return_address(0));
199 * We can't call find_vm_area() in interrupt context, and
200 * free_thread_stack() can be called in interrupt context,
201 * so cache the vm_struct.
204 tsk
->stack_vm_area
= find_vm_area(stack
);
207 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP
,
210 return page
? page_address(page
) : NULL
;
214 static inline void free_thread_stack(struct task_struct
*tsk
)
216 #ifdef CONFIG_VMAP_STACK
217 if (task_stack_vm_area(tsk
)) {
221 local_irq_save(flags
);
222 for (i
= 0; i
< NR_CACHED_STACKS
; i
++) {
223 if (this_cpu_read(cached_stacks
[i
]))
226 this_cpu_write(cached_stacks
[i
], tsk
->stack_vm_area
);
227 local_irq_restore(flags
);
230 local_irq_restore(flags
);
237 __free_pages(virt_to_page(tsk
->stack
), THREAD_SIZE_ORDER
);
240 static struct kmem_cache
*thread_stack_cache
;
242 static unsigned long *alloc_thread_stack_node(struct task_struct
*tsk
,
245 return kmem_cache_alloc_node(thread_stack_cache
, THREADINFO_GFP
, node
);
248 static void free_thread_stack(struct task_struct
*tsk
)
250 kmem_cache_free(thread_stack_cache
, tsk
->stack
);
253 void thread_stack_cache_init(void)
255 thread_stack_cache
= kmem_cache_create("thread_stack", THREAD_SIZE
,
256 THREAD_SIZE
, 0, NULL
);
257 BUG_ON(thread_stack_cache
== NULL
);
262 /* SLAB cache for signal_struct structures (tsk->signal) */
263 static struct kmem_cache
*signal_cachep
;
265 /* SLAB cache for sighand_struct structures (tsk->sighand) */
266 struct kmem_cache
*sighand_cachep
;
268 /* SLAB cache for files_struct structures (tsk->files) */
269 struct kmem_cache
*files_cachep
;
271 /* SLAB cache for fs_struct structures (tsk->fs) */
272 struct kmem_cache
*fs_cachep
;
274 /* SLAB cache for vm_area_struct structures */
275 struct kmem_cache
*vm_area_cachep
;
277 /* SLAB cache for mm_struct structures (tsk->mm) */
278 static struct kmem_cache
*mm_cachep
;
280 static void account_kernel_stack(struct task_struct
*tsk
, int account
)
282 void *stack
= task_stack_page(tsk
);
283 struct vm_struct
*vm
= task_stack_vm_area(tsk
);
285 BUILD_BUG_ON(IS_ENABLED(CONFIG_VMAP_STACK
) && PAGE_SIZE
% 1024 != 0);
290 BUG_ON(vm
->nr_pages
!= THREAD_SIZE
/ PAGE_SIZE
);
292 for (i
= 0; i
< THREAD_SIZE
/ PAGE_SIZE
; i
++) {
293 mod_zone_page_state(page_zone(vm
->pages
[i
]),
295 PAGE_SIZE
/ 1024 * account
);
298 /* All stack pages belong to the same memcg. */
299 memcg_kmem_update_page_stat(vm
->pages
[0], MEMCG_KERNEL_STACK_KB
,
300 account
* (THREAD_SIZE
/ 1024));
303 * All stack pages are in the same zone and belong to the
306 struct page
*first_page
= virt_to_page(stack
);
308 mod_zone_page_state(page_zone(first_page
), NR_KERNEL_STACK_KB
,
309 THREAD_SIZE
/ 1024 * account
);
311 memcg_kmem_update_page_stat(first_page
, MEMCG_KERNEL_STACK_KB
,
312 account
* (THREAD_SIZE
/ 1024));
316 static void release_task_stack(struct task_struct
*tsk
)
318 if (WARN_ON(tsk
->state
!= TASK_DEAD
))
319 return; /* Better to leak the stack than to free prematurely */
321 account_kernel_stack(tsk
, -1);
322 arch_release_thread_stack(tsk
->stack
);
323 free_thread_stack(tsk
);
325 #ifdef CONFIG_VMAP_STACK
326 tsk
->stack_vm_area
= NULL
;
330 #ifdef CONFIG_THREAD_INFO_IN_TASK
331 void put_task_stack(struct task_struct
*tsk
)
333 if (atomic_dec_and_test(&tsk
->stack_refcount
))
334 release_task_stack(tsk
);
338 void free_task(struct task_struct
*tsk
)
340 #ifndef CONFIG_THREAD_INFO_IN_TASK
342 * The task is finally done with both the stack and thread_info,
345 release_task_stack(tsk
);
348 * If the task had a separate stack allocation, it should be gone
351 WARN_ON_ONCE(atomic_read(&tsk
->stack_refcount
) != 0);
353 rt_mutex_debug_task_free(tsk
);
354 ftrace_graph_exit_task(tsk
);
355 put_seccomp_filter(tsk
);
356 arch_release_task_struct(tsk
);
357 if (tsk
->flags
& PF_KTHREAD
)
358 free_kthread_struct(tsk
);
359 free_task_struct(tsk
);
361 EXPORT_SYMBOL(free_task
);
363 static inline void free_signal_struct(struct signal_struct
*sig
)
365 taskstats_tgid_free(sig
);
366 sched_autogroup_exit(sig
);
368 * __mmdrop is not safe to call from softirq context on x86 due to
369 * pgd_dtor so postpone it to the async context
372 mmdrop_async(sig
->oom_mm
);
373 kmem_cache_free(signal_cachep
, sig
);
376 static inline void put_signal_struct(struct signal_struct
*sig
)
378 if (atomic_dec_and_test(&sig
->sigcnt
))
379 free_signal_struct(sig
);
382 void __put_task_struct(struct task_struct
*tsk
)
384 WARN_ON(!tsk
->exit_state
);
385 WARN_ON(atomic_read(&tsk
->usage
));
386 WARN_ON(tsk
== current
);
390 security_task_free(tsk
);
392 delayacct_tsk_free(tsk
);
393 put_signal_struct(tsk
->signal
);
395 if (!profile_handoff_task(tsk
))
398 EXPORT_SYMBOL_GPL(__put_task_struct
);
400 void __init __weak
arch_task_cache_init(void) { }
405 static void set_max_threads(unsigned int max_threads_suggested
)
410 * The number of threads shall be limited such that the thread
411 * structures may only consume a small part of the available memory.
413 if (fls64(totalram_pages
) + fls64(PAGE_SIZE
) > 64)
414 threads
= MAX_THREADS
;
416 threads
= div64_u64((u64
) totalram_pages
* (u64
) PAGE_SIZE
,
417 (u64
) THREAD_SIZE
* 8UL);
419 if (threads
> max_threads_suggested
)
420 threads
= max_threads_suggested
;
422 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
425 #ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
426 /* Initialized by the architecture: */
427 int arch_task_struct_size __read_mostly
;
430 void __init
fork_init(void)
433 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
434 #ifndef ARCH_MIN_TASKALIGN
435 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
437 /* create a slab on which task_structs can be allocated */
438 task_struct_cachep
= kmem_cache_create("task_struct",
439 arch_task_struct_size
, ARCH_MIN_TASKALIGN
,
440 SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
, NULL
);
443 /* do the arch specific task caches init */
444 arch_task_cache_init();
446 set_max_threads(MAX_THREADS
);
448 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
449 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
450 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
451 init_task
.signal
->rlim
[RLIMIT_NPROC
];
453 for (i
= 0; i
< UCOUNT_COUNTS
; i
++) {
454 init_user_ns
.ucount_max
[i
] = max_threads
/2;
458 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
459 struct task_struct
*src
)
465 void set_task_stack_end_magic(struct task_struct
*tsk
)
467 unsigned long *stackend
;
469 stackend
= end_of_stack(tsk
);
470 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
473 static struct task_struct
*dup_task_struct(struct task_struct
*orig
, int node
)
475 struct task_struct
*tsk
;
476 unsigned long *stack
;
477 struct vm_struct
*stack_vm_area
;
480 if (node
== NUMA_NO_NODE
)
481 node
= tsk_fork_get_node(orig
);
482 tsk
= alloc_task_struct_node(node
);
486 stack
= alloc_thread_stack_node(tsk
, node
);
490 stack_vm_area
= task_stack_vm_area(tsk
);
492 err
= arch_dup_task_struct(tsk
, orig
);
495 * arch_dup_task_struct() clobbers the stack-related fields. Make
496 * sure they're properly initialized before using any stack-related
500 #ifdef CONFIG_VMAP_STACK
501 tsk
->stack_vm_area
= stack_vm_area
;
503 #ifdef CONFIG_THREAD_INFO_IN_TASK
504 atomic_set(&tsk
->stack_refcount
, 1);
510 #ifdef CONFIG_SECCOMP
512 * We must handle setting up seccomp filters once we're under
513 * the sighand lock in case orig has changed between now and
514 * then. Until then, filter must be NULL to avoid messing up
515 * the usage counts on the error path calling free_task.
517 tsk
->seccomp
.filter
= NULL
;
520 setup_thread_stack(tsk
, orig
);
521 clear_user_return_notifier(tsk
);
522 clear_tsk_need_resched(tsk
);
523 set_task_stack_end_magic(tsk
);
525 #ifdef CONFIG_CC_STACKPROTECTOR
526 tsk
->stack_canary
= get_random_int();
530 * One for us, one for whoever does the "release_task()" (usually
533 atomic_set(&tsk
->usage
, 2);
534 #ifdef CONFIG_BLK_DEV_IO_TRACE
537 tsk
->splice_pipe
= NULL
;
538 tsk
->task_frag
.page
= NULL
;
539 tsk
->wake_q
.next
= NULL
;
541 account_kernel_stack(tsk
, 1);
548 free_thread_stack(tsk
);
550 free_task_struct(tsk
);
555 static __latent_entropy
int dup_mmap(struct mm_struct
*mm
,
556 struct mm_struct
*oldmm
)
558 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
559 struct rb_node
**rb_link
, *rb_parent
;
561 unsigned long charge
;
563 uprobe_start_dup_mmap();
564 if (down_write_killable(&oldmm
->mmap_sem
)) {
566 goto fail_uprobe_end
;
568 flush_cache_dup_mm(oldmm
);
569 uprobe_dup_mmap(oldmm
, mm
);
571 * Not linked in yet - no deadlock potential:
573 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
575 /* No ordering required: file already has been exposed. */
576 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
578 mm
->total_vm
= oldmm
->total_vm
;
579 mm
->data_vm
= oldmm
->data_vm
;
580 mm
->exec_vm
= oldmm
->exec_vm
;
581 mm
->stack_vm
= oldmm
->stack_vm
;
583 rb_link
= &mm
->mm_rb
.rb_node
;
586 retval
= ksm_fork(mm
, oldmm
);
589 retval
= khugepaged_fork(mm
, oldmm
);
594 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
597 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
598 vm_stat_account(mm
, mpnt
->vm_flags
, -vma_pages(mpnt
));
602 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
603 unsigned long len
= vma_pages(mpnt
);
605 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
609 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
613 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
614 retval
= vma_dup_policy(mpnt
, tmp
);
616 goto fail_nomem_policy
;
618 if (anon_vma_fork(tmp
, mpnt
))
619 goto fail_nomem_anon_vma_fork
;
621 ~(VM_LOCKED
|VM_LOCKONFAULT
|VM_UFFD_MISSING
|VM_UFFD_WP
);
622 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
623 tmp
->vm_userfaultfd_ctx
= NULL_VM_UFFD_CTX
;
626 struct inode
*inode
= file_inode(file
);
627 struct address_space
*mapping
= file
->f_mapping
;
630 if (tmp
->vm_flags
& VM_DENYWRITE
)
631 atomic_dec(&inode
->i_writecount
);
632 i_mmap_lock_write(mapping
);
633 if (tmp
->vm_flags
& VM_SHARED
)
634 atomic_inc(&mapping
->i_mmap_writable
);
635 flush_dcache_mmap_lock(mapping
);
636 /* insert tmp into the share list, just after mpnt */
637 vma_interval_tree_insert_after(tmp
, mpnt
,
639 flush_dcache_mmap_unlock(mapping
);
640 i_mmap_unlock_write(mapping
);
644 * Clear hugetlb-related page reserves for children. This only
645 * affects MAP_PRIVATE mappings. Faults generated by the child
646 * are not guaranteed to succeed, even if read-only
648 if (is_vm_hugetlb_page(tmp
))
649 reset_vma_resv_huge_pages(tmp
);
652 * Link in the new vma and copy the page table entries.
655 pprev
= &tmp
->vm_next
;
659 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
660 rb_link
= &tmp
->vm_rb
.rb_right
;
661 rb_parent
= &tmp
->vm_rb
;
664 retval
= copy_page_range(mm
, oldmm
, mpnt
);
666 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
667 tmp
->vm_ops
->open(tmp
);
672 /* a new mm has just been created */
673 arch_dup_mmap(oldmm
, mm
);
676 up_write(&mm
->mmap_sem
);
678 up_write(&oldmm
->mmap_sem
);
680 uprobe_end_dup_mmap();
682 fail_nomem_anon_vma_fork
:
683 mpol_put(vma_policy(tmp
));
685 kmem_cache_free(vm_area_cachep
, tmp
);
688 vm_unacct_memory(charge
);
692 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
694 mm
->pgd
= pgd_alloc(mm
);
695 if (unlikely(!mm
->pgd
))
700 static inline void mm_free_pgd(struct mm_struct
*mm
)
702 pgd_free(mm
, mm
->pgd
);
705 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
707 down_write(&oldmm
->mmap_sem
);
708 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
709 up_write(&oldmm
->mmap_sem
);
712 #define mm_alloc_pgd(mm) (0)
713 #define mm_free_pgd(mm)
714 #endif /* CONFIG_MMU */
716 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
718 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
719 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
721 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
723 static int __init
coredump_filter_setup(char *s
)
725 default_dump_filter
=
726 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
727 MMF_DUMP_FILTER_MASK
;
731 __setup("coredump_filter=", coredump_filter_setup
);
733 #include <linux/init_task.h>
735 static void mm_init_aio(struct mm_struct
*mm
)
738 spin_lock_init(&mm
->ioctx_lock
);
739 mm
->ioctx_table
= NULL
;
743 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
750 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
)
754 mm
->vmacache_seqnum
= 0;
755 atomic_set(&mm
->mm_users
, 1);
756 atomic_set(&mm
->mm_count
, 1);
757 init_rwsem(&mm
->mmap_sem
);
758 INIT_LIST_HEAD(&mm
->mmlist
);
759 mm
->core_state
= NULL
;
760 atomic_long_set(&mm
->nr_ptes
, 0);
765 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
766 spin_lock_init(&mm
->page_table_lock
);
769 mm_init_owner(mm
, p
);
770 mmu_notifier_mm_init(mm
);
771 clear_tlb_flush_pending(mm
);
772 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
773 mm
->pmd_huge_pte
= NULL
;
777 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
778 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
780 mm
->flags
= default_dump_filter
;
784 if (mm_alloc_pgd(mm
))
787 if (init_new_context(p
, mm
))
799 static void check_mm(struct mm_struct
*mm
)
803 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
804 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
807 printk(KERN_ALERT
"BUG: Bad rss-counter state "
808 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
811 if (atomic_long_read(&mm
->nr_ptes
))
812 pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
813 atomic_long_read(&mm
->nr_ptes
));
815 pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
818 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
819 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
824 * Allocate and initialize an mm_struct.
826 struct mm_struct
*mm_alloc(void)
828 struct mm_struct
*mm
;
834 memset(mm
, 0, sizeof(*mm
));
835 return mm_init(mm
, current
);
839 * Called when the last reference to the mm
840 * is dropped: either by a lazy thread or by
841 * mmput. Free the page directory and the mm.
843 void __mmdrop(struct mm_struct
*mm
)
845 BUG_ON(mm
== &init_mm
);
848 mmu_notifier_mm_destroy(mm
);
852 EXPORT_SYMBOL_GPL(__mmdrop
);
854 static inline void __mmput(struct mm_struct
*mm
)
856 VM_BUG_ON(atomic_read(&mm
->mm_users
));
858 uprobe_clear_state(mm
);
861 khugepaged_exit(mm
); /* must run before exit_mmap */
863 mm_put_huge_zero_page(mm
);
864 set_mm_exe_file(mm
, NULL
);
865 if (!list_empty(&mm
->mmlist
)) {
866 spin_lock(&mmlist_lock
);
867 list_del(&mm
->mmlist
);
868 spin_unlock(&mmlist_lock
);
871 module_put(mm
->binfmt
->module
);
872 set_bit(MMF_OOM_SKIP
, &mm
->flags
);
877 * Decrement the use count and release all resources for an mm.
879 void mmput(struct mm_struct
*mm
)
883 if (atomic_dec_and_test(&mm
->mm_users
))
886 EXPORT_SYMBOL_GPL(mmput
);
889 static void mmput_async_fn(struct work_struct
*work
)
891 struct mm_struct
*mm
= container_of(work
, struct mm_struct
, async_put_work
);
895 void mmput_async(struct mm_struct
*mm
)
897 if (atomic_dec_and_test(&mm
->mm_users
)) {
898 INIT_WORK(&mm
->async_put_work
, mmput_async_fn
);
899 schedule_work(&mm
->async_put_work
);
905 * set_mm_exe_file - change a reference to the mm's executable file
907 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
909 * Main users are mmput() and sys_execve(). Callers prevent concurrent
910 * invocations: in mmput() nobody alive left, in execve task is single
911 * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
912 * mm->exe_file, but does so without using set_mm_exe_file() in order
913 * to do avoid the need for any locks.
915 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
917 struct file
*old_exe_file
;
920 * It is safe to dereference the exe_file without RCU as
921 * this function is only called if nobody else can access
922 * this mm -- see comment above for justification.
924 old_exe_file
= rcu_dereference_raw(mm
->exe_file
);
927 get_file(new_exe_file
);
928 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
934 * get_mm_exe_file - acquire a reference to the mm's executable file
936 * Returns %NULL if mm has no associated executable file.
937 * User must release file via fput().
939 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
941 struct file
*exe_file
;
944 exe_file
= rcu_dereference(mm
->exe_file
);
945 if (exe_file
&& !get_file_rcu(exe_file
))
950 EXPORT_SYMBOL(get_mm_exe_file
);
953 * get_task_exe_file - acquire a reference to the task's executable file
955 * Returns %NULL if task's mm (if any) has no associated executable file or
956 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
957 * User must release file via fput().
959 struct file
*get_task_exe_file(struct task_struct
*task
)
961 struct file
*exe_file
= NULL
;
962 struct mm_struct
*mm
;
967 if (!(task
->flags
& PF_KTHREAD
))
968 exe_file
= get_mm_exe_file(mm
);
973 EXPORT_SYMBOL(get_task_exe_file
);
976 * get_task_mm - acquire a reference to the task's mm
978 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
979 * this kernel workthread has transiently adopted a user mm with use_mm,
980 * to do its AIO) is not set and if so returns a reference to it, after
981 * bumping up the use count. User must release the mm via mmput()
982 * after use. Typically used by /proc and ptrace.
984 struct mm_struct
*get_task_mm(struct task_struct
*task
)
986 struct mm_struct
*mm
;
991 if (task
->flags
& PF_KTHREAD
)
994 atomic_inc(&mm
->mm_users
);
999 EXPORT_SYMBOL_GPL(get_task_mm
);
1001 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
1003 struct mm_struct
*mm
;
1006 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
1008 return ERR_PTR(err
);
1010 mm
= get_task_mm(task
);
1011 if (mm
&& mm
!= current
->mm
&&
1012 !ptrace_may_access(task
, mode
)) {
1014 mm
= ERR_PTR(-EACCES
);
1016 mutex_unlock(&task
->signal
->cred_guard_mutex
);
1021 static void complete_vfork_done(struct task_struct
*tsk
)
1023 struct completion
*vfork
;
1026 vfork
= tsk
->vfork_done
;
1027 if (likely(vfork
)) {
1028 tsk
->vfork_done
= NULL
;
1034 static int wait_for_vfork_done(struct task_struct
*child
,
1035 struct completion
*vfork
)
1039 freezer_do_not_count();
1040 killed
= wait_for_completion_killable(vfork
);
1045 child
->vfork_done
= NULL
;
1049 put_task_struct(child
);
1053 /* Please note the differences between mmput and mm_release.
1054 * mmput is called whenever we stop holding onto a mm_struct,
1055 * error success whatever.
1057 * mm_release is called after a mm_struct has been removed
1058 * from the current process.
1060 * This difference is important for error handling, when we
1061 * only half set up a mm_struct for a new process and need to restore
1062 * the old one. Because we mmput the new mm_struct before
1063 * restoring the old one. . .
1064 * Eric Biederman 10 January 1998
1066 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
1068 /* Get rid of any futexes when releasing the mm */
1070 if (unlikely(tsk
->robust_list
)) {
1071 exit_robust_list(tsk
);
1072 tsk
->robust_list
= NULL
;
1074 #ifdef CONFIG_COMPAT
1075 if (unlikely(tsk
->compat_robust_list
)) {
1076 compat_exit_robust_list(tsk
);
1077 tsk
->compat_robust_list
= NULL
;
1080 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1081 exit_pi_state_list(tsk
);
1084 uprobe_free_utask(tsk
);
1086 /* Get rid of any cached register state */
1087 deactivate_mm(tsk
, mm
);
1090 * Signal userspace if we're not exiting with a core dump
1091 * because we want to leave the value intact for debugging
1094 if (tsk
->clear_child_tid
) {
1095 if (!(tsk
->signal
->flags
& SIGNAL_GROUP_COREDUMP
) &&
1096 atomic_read(&mm
->mm_users
) > 1) {
1098 * We don't check the error code - if userspace has
1099 * not set up a proper pointer then tough luck.
1101 put_user(0, tsk
->clear_child_tid
);
1102 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
1105 tsk
->clear_child_tid
= NULL
;
1109 * All done, finally we can wake up parent and return this mm to him.
1110 * Also kthread_stop() uses this completion for synchronization.
1112 if (tsk
->vfork_done
)
1113 complete_vfork_done(tsk
);
1117 * Allocate a new mm structure and copy contents from the
1118 * mm structure of the passed in task structure.
1120 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
1122 struct mm_struct
*mm
, *oldmm
= current
->mm
;
1129 memcpy(mm
, oldmm
, sizeof(*mm
));
1131 if (!mm_init(mm
, tsk
))
1134 err
= dup_mmap(mm
, oldmm
);
1138 mm
->hiwater_rss
= get_mm_rss(mm
);
1139 mm
->hiwater_vm
= mm
->total_vm
;
1141 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
1147 /* don't put binfmt in mmput, we haven't got module yet */
1155 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
1157 struct mm_struct
*mm
, *oldmm
;
1160 tsk
->min_flt
= tsk
->maj_flt
= 0;
1161 tsk
->nvcsw
= tsk
->nivcsw
= 0;
1162 #ifdef CONFIG_DETECT_HUNG_TASK
1163 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
1167 tsk
->active_mm
= NULL
;
1170 * Are we cloning a kernel thread?
1172 * We need to steal a active VM for that..
1174 oldmm
= current
->mm
;
1178 /* initialize the new vmacache entries */
1179 vmacache_flush(tsk
);
1181 if (clone_flags
& CLONE_VM
) {
1182 atomic_inc(&oldmm
->mm_users
);
1194 tsk
->active_mm
= mm
;
1201 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
1203 struct fs_struct
*fs
= current
->fs
;
1204 if (clone_flags
& CLONE_FS
) {
1205 /* tsk->fs is already what we want */
1206 spin_lock(&fs
->lock
);
1208 spin_unlock(&fs
->lock
);
1212 spin_unlock(&fs
->lock
);
1215 tsk
->fs
= copy_fs_struct(fs
);
1221 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
1223 struct files_struct
*oldf
, *newf
;
1227 * A background process may not have any files ...
1229 oldf
= current
->files
;
1233 if (clone_flags
& CLONE_FILES
) {
1234 atomic_inc(&oldf
->count
);
1238 newf
= dup_fd(oldf
, &error
);
1248 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1251 struct io_context
*ioc
= current
->io_context
;
1252 struct io_context
*new_ioc
;
1257 * Share io context with parent, if CLONE_IO is set
1259 if (clone_flags
& CLONE_IO
) {
1261 tsk
->io_context
= ioc
;
1262 } else if (ioprio_valid(ioc
->ioprio
)) {
1263 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1264 if (unlikely(!new_ioc
))
1267 new_ioc
->ioprio
= ioc
->ioprio
;
1268 put_io_context(new_ioc
);
1274 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1276 struct sighand_struct
*sig
;
1278 if (clone_flags
& CLONE_SIGHAND
) {
1279 atomic_inc(¤t
->sighand
->count
);
1282 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1283 rcu_assign_pointer(tsk
->sighand
, sig
);
1287 atomic_set(&sig
->count
, 1);
1288 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1292 void __cleanup_sighand(struct sighand_struct
*sighand
)
1294 if (atomic_dec_and_test(&sighand
->count
)) {
1295 signalfd_cleanup(sighand
);
1297 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
1298 * without an RCU grace period, see __lock_task_sighand().
1300 kmem_cache_free(sighand_cachep
, sighand
);
1305 * Initialize POSIX timer handling for a thread group.
1307 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1309 unsigned long cpu_limit
;
1311 cpu_limit
= READ_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1312 if (cpu_limit
!= RLIM_INFINITY
) {
1313 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1314 sig
->cputimer
.running
= true;
1317 /* The timer lists. */
1318 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1319 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1320 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1323 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1325 struct signal_struct
*sig
;
1327 if (clone_flags
& CLONE_THREAD
)
1330 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1335 sig
->nr_threads
= 1;
1336 atomic_set(&sig
->live
, 1);
1337 atomic_set(&sig
->sigcnt
, 1);
1339 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1340 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1341 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1343 init_waitqueue_head(&sig
->wait_chldexit
);
1344 sig
->curr_target
= tsk
;
1345 init_sigpending(&sig
->shared_pending
);
1346 INIT_LIST_HEAD(&sig
->posix_timers
);
1347 seqlock_init(&sig
->stats_lock
);
1348 prev_cputime_init(&sig
->prev_cputime
);
1350 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1351 sig
->real_timer
.function
= it_real_fn
;
1353 task_lock(current
->group_leader
);
1354 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1355 task_unlock(current
->group_leader
);
1357 posix_cpu_timers_init_group(sig
);
1359 tty_audit_fork(sig
);
1360 sched_autogroup_fork(sig
);
1362 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1363 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1365 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1366 current
->signal
->is_child_subreaper
;
1368 mutex_init(&sig
->cred_guard_mutex
);
1373 static void copy_seccomp(struct task_struct
*p
)
1375 #ifdef CONFIG_SECCOMP
1377 * Must be called with sighand->lock held, which is common to
1378 * all threads in the group. Holding cred_guard_mutex is not
1379 * needed because this new task is not yet running and cannot
1382 assert_spin_locked(¤t
->sighand
->siglock
);
1384 /* Ref-count the new filter user, and assign it. */
1385 get_seccomp_filter(current
);
1386 p
->seccomp
= current
->seccomp
;
1389 * Explicitly enable no_new_privs here in case it got set
1390 * between the task_struct being duplicated and holding the
1391 * sighand lock. The seccomp state and nnp must be in sync.
1393 if (task_no_new_privs(current
))
1394 task_set_no_new_privs(p
);
1397 * If the parent gained a seccomp mode after copying thread
1398 * flags and between before we held the sighand lock, we have
1399 * to manually enable the seccomp thread flag here.
1401 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1402 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1406 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1408 current
->clear_child_tid
= tidptr
;
1410 return task_pid_vnr(current
);
1413 static void rt_mutex_init_task(struct task_struct
*p
)
1415 raw_spin_lock_init(&p
->pi_lock
);
1416 #ifdef CONFIG_RT_MUTEXES
1417 p
->pi_waiters
= RB_ROOT
;
1418 p
->pi_waiters_leftmost
= NULL
;
1419 p
->pi_blocked_on
= NULL
;
1424 * Initialize POSIX timer handling for a single task.
1426 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1428 tsk
->cputime_expires
.prof_exp
= 0;
1429 tsk
->cputime_expires
.virt_exp
= 0;
1430 tsk
->cputime_expires
.sched_exp
= 0;
1431 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1432 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1433 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1437 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1439 task
->pids
[type
].pid
= pid
;
1443 * This creates a new process as a copy of the old one,
1444 * but does not actually start it yet.
1446 * It copies the registers, and all the appropriate
1447 * parts of the process environment (as per the clone
1448 * flags). The actual kick-off is left to the caller.
1450 static __latent_entropy
struct task_struct
*copy_process(
1451 unsigned long clone_flags
,
1452 unsigned long stack_start
,
1453 unsigned long stack_size
,
1454 int __user
*child_tidptr
,
1461 struct task_struct
*p
;
1463 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1464 return ERR_PTR(-EINVAL
);
1466 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1467 return ERR_PTR(-EINVAL
);
1470 * Thread groups must share signals as well, and detached threads
1471 * can only be started up within the thread group.
1473 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1474 return ERR_PTR(-EINVAL
);
1477 * Shared signal handlers imply shared VM. By way of the above,
1478 * thread groups also imply shared VM. Blocking this case allows
1479 * for various simplifications in other code.
1481 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1482 return ERR_PTR(-EINVAL
);
1485 * Siblings of global init remain as zombies on exit since they are
1486 * not reaped by their parent (swapper). To solve this and to avoid
1487 * multi-rooted process trees, prevent global and container-inits
1488 * from creating siblings.
1490 if ((clone_flags
& CLONE_PARENT
) &&
1491 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1492 return ERR_PTR(-EINVAL
);
1495 * If the new process will be in a different pid or user namespace
1496 * do not allow it to share a thread group with the forking task.
1498 if (clone_flags
& CLONE_THREAD
) {
1499 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1500 (task_active_pid_ns(current
) !=
1501 current
->nsproxy
->pid_ns_for_children
))
1502 return ERR_PTR(-EINVAL
);
1505 retval
= security_task_create(clone_flags
);
1510 p
= dup_task_struct(current
, node
);
1514 ftrace_graph_init_task(p
);
1516 rt_mutex_init_task(p
);
1518 #ifdef CONFIG_PROVE_LOCKING
1519 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1520 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1523 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1524 task_rlimit(p
, RLIMIT_NPROC
)) {
1525 if (p
->real_cred
->user
!= INIT_USER
&&
1526 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1529 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1531 retval
= copy_creds(p
, clone_flags
);
1536 * If multiple threads are within copy_process(), then this check
1537 * triggers too late. This doesn't hurt, the check is only there
1538 * to stop root fork bombs.
1541 if (nr_threads
>= max_threads
)
1542 goto bad_fork_cleanup_count
;
1544 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1545 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
1546 p
->flags
|= PF_FORKNOEXEC
;
1547 INIT_LIST_HEAD(&p
->children
);
1548 INIT_LIST_HEAD(&p
->sibling
);
1549 rcu_copy_process(p
);
1550 p
->vfork_done
= NULL
;
1551 spin_lock_init(&p
->alloc_lock
);
1553 init_sigpending(&p
->pending
);
1555 p
->utime
= p
->stime
= p
->gtime
= 0;
1556 #ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
1557 p
->utimescaled
= p
->stimescaled
= 0;
1559 prev_cputime_init(&p
->prev_cputime
);
1561 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1562 seqcount_init(&p
->vtime_seqcount
);
1564 p
->vtime_snap_whence
= VTIME_INACTIVE
;
1567 #if defined(SPLIT_RSS_COUNTING)
1568 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1571 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1573 task_io_accounting_init(&p
->ioac
);
1574 acct_clear_integrals(p
);
1576 posix_cpu_timers_init(p
);
1578 p
->start_time
= ktime_get_ns();
1579 p
->real_start_time
= ktime_get_boot_ns();
1580 p
->io_context
= NULL
;
1581 p
->audit_context
= NULL
;
1584 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1585 if (IS_ERR(p
->mempolicy
)) {
1586 retval
= PTR_ERR(p
->mempolicy
);
1587 p
->mempolicy
= NULL
;
1588 goto bad_fork_cleanup_threadgroup_lock
;
1591 #ifdef CONFIG_CPUSETS
1592 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1593 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1594 seqcount_init(&p
->mems_allowed_seq
);
1596 #ifdef CONFIG_TRACE_IRQFLAGS
1598 p
->hardirqs_enabled
= 0;
1599 p
->hardirq_enable_ip
= 0;
1600 p
->hardirq_enable_event
= 0;
1601 p
->hardirq_disable_ip
= _THIS_IP_
;
1602 p
->hardirq_disable_event
= 0;
1603 p
->softirqs_enabled
= 1;
1604 p
->softirq_enable_ip
= _THIS_IP_
;
1605 p
->softirq_enable_event
= 0;
1606 p
->softirq_disable_ip
= 0;
1607 p
->softirq_disable_event
= 0;
1608 p
->hardirq_context
= 0;
1609 p
->softirq_context
= 0;
1612 p
->pagefault_disabled
= 0;
1614 #ifdef CONFIG_LOCKDEP
1615 p
->lockdep_depth
= 0; /* no locks held yet */
1616 p
->curr_chain_key
= 0;
1617 p
->lockdep_recursion
= 0;
1620 #ifdef CONFIG_DEBUG_MUTEXES
1621 p
->blocked_on
= NULL
; /* not blocked yet */
1623 #ifdef CONFIG_BCACHE
1624 p
->sequential_io
= 0;
1625 p
->sequential_io_avg
= 0;
1628 /* Perform scheduler related setup. Assign this task to a CPU. */
1629 retval
= sched_fork(clone_flags
, p
);
1631 goto bad_fork_cleanup_policy
;
1633 retval
= perf_event_init_task(p
);
1635 goto bad_fork_cleanup_policy
;
1636 retval
= audit_alloc(p
);
1638 goto bad_fork_cleanup_perf
;
1639 /* copy all the process information */
1641 retval
= copy_semundo(clone_flags
, p
);
1643 goto bad_fork_cleanup_audit
;
1644 retval
= copy_files(clone_flags
, p
);
1646 goto bad_fork_cleanup_semundo
;
1647 retval
= copy_fs(clone_flags
, p
);
1649 goto bad_fork_cleanup_files
;
1650 retval
= copy_sighand(clone_flags
, p
);
1652 goto bad_fork_cleanup_fs
;
1653 retval
= copy_signal(clone_flags
, p
);
1655 goto bad_fork_cleanup_sighand
;
1656 retval
= copy_mm(clone_flags
, p
);
1658 goto bad_fork_cleanup_signal
;
1659 retval
= copy_namespaces(clone_flags
, p
);
1661 goto bad_fork_cleanup_mm
;
1662 retval
= copy_io(clone_flags
, p
);
1664 goto bad_fork_cleanup_namespaces
;
1665 retval
= copy_thread_tls(clone_flags
, stack_start
, stack_size
, p
, tls
);
1667 goto bad_fork_cleanup_io
;
1669 if (pid
!= &init_struct_pid
) {
1670 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1672 retval
= PTR_ERR(pid
);
1673 goto bad_fork_cleanup_thread
;
1677 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1679 * Clear TID on mm_release()?
1681 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1686 p
->robust_list
= NULL
;
1687 #ifdef CONFIG_COMPAT
1688 p
->compat_robust_list
= NULL
;
1690 INIT_LIST_HEAD(&p
->pi_state_list
);
1691 p
->pi_state_cache
= NULL
;
1694 * sigaltstack should be cleared when sharing the same VM
1696 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1700 * Syscall tracing and stepping should be turned off in the
1701 * child regardless of CLONE_PTRACE.
1703 user_disable_single_step(p
);
1704 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1705 #ifdef TIF_SYSCALL_EMU
1706 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1708 clear_all_latency_tracing(p
);
1710 /* ok, now we should be set up.. */
1711 p
->pid
= pid_nr(pid
);
1712 if (clone_flags
& CLONE_THREAD
) {
1713 p
->exit_signal
= -1;
1714 p
->group_leader
= current
->group_leader
;
1715 p
->tgid
= current
->tgid
;
1717 if (clone_flags
& CLONE_PARENT
)
1718 p
->exit_signal
= current
->group_leader
->exit_signal
;
1720 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1721 p
->group_leader
= p
;
1726 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1727 p
->dirty_paused_when
= 0;
1729 p
->pdeath_signal
= 0;
1730 INIT_LIST_HEAD(&p
->thread_group
);
1731 p
->task_works
= NULL
;
1733 threadgroup_change_begin(current
);
1735 * Ensure that the cgroup subsystem policies allow the new process to be
1736 * forked. It should be noted the the new process's css_set can be changed
1737 * between here and cgroup_post_fork() if an organisation operation is in
1740 retval
= cgroup_can_fork(p
);
1742 goto bad_fork_free_pid
;
1745 * Make it visible to the rest of the system, but dont wake it up yet.
1746 * Need tasklist lock for parent etc handling!
1748 write_lock_irq(&tasklist_lock
);
1750 /* CLONE_PARENT re-uses the old parent */
1751 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1752 p
->real_parent
= current
->real_parent
;
1753 p
->parent_exec_id
= current
->parent_exec_id
;
1755 p
->real_parent
= current
;
1756 p
->parent_exec_id
= current
->self_exec_id
;
1759 spin_lock(¤t
->sighand
->siglock
);
1762 * Copy seccomp details explicitly here, in case they were changed
1763 * before holding sighand lock.
1768 * Process group and session signals need to be delivered to just the
1769 * parent before the fork or both the parent and the child after the
1770 * fork. Restart if a signal comes in before we add the new process to
1771 * it's process group.
1772 * A fatal signal pending means that current will exit, so the new
1773 * thread can't slip out of an OOM kill (or normal SIGKILL).
1775 recalc_sigpending();
1776 if (signal_pending(current
)) {
1777 spin_unlock(¤t
->sighand
->siglock
);
1778 write_unlock_irq(&tasklist_lock
);
1779 retval
= -ERESTARTNOINTR
;
1780 goto bad_fork_cancel_cgroup
;
1783 if (likely(p
->pid
)) {
1784 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1786 init_task_pid(p
, PIDTYPE_PID
, pid
);
1787 if (thread_group_leader(p
)) {
1788 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1789 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1791 if (is_child_reaper(pid
)) {
1792 ns_of_pid(pid
)->child_reaper
= p
;
1793 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1796 p
->signal
->leader_pid
= pid
;
1797 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1798 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1799 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1800 attach_pid(p
, PIDTYPE_PGID
);
1801 attach_pid(p
, PIDTYPE_SID
);
1802 __this_cpu_inc(process_counts
);
1804 current
->signal
->nr_threads
++;
1805 atomic_inc(¤t
->signal
->live
);
1806 atomic_inc(¤t
->signal
->sigcnt
);
1807 list_add_tail_rcu(&p
->thread_group
,
1808 &p
->group_leader
->thread_group
);
1809 list_add_tail_rcu(&p
->thread_node
,
1810 &p
->signal
->thread_head
);
1812 attach_pid(p
, PIDTYPE_PID
);
1817 spin_unlock(¤t
->sighand
->siglock
);
1818 syscall_tracepoint_update(p
);
1819 write_unlock_irq(&tasklist_lock
);
1821 proc_fork_connector(p
);
1822 cgroup_post_fork(p
);
1823 threadgroup_change_end(current
);
1826 trace_task_newtask(p
, clone_flags
);
1827 uprobe_copy_process(p
, clone_flags
);
1831 bad_fork_cancel_cgroup
:
1832 cgroup_cancel_fork(p
);
1834 threadgroup_change_end(current
);
1835 if (pid
!= &init_struct_pid
)
1837 bad_fork_cleanup_thread
:
1839 bad_fork_cleanup_io
:
1842 bad_fork_cleanup_namespaces
:
1843 exit_task_namespaces(p
);
1844 bad_fork_cleanup_mm
:
1847 bad_fork_cleanup_signal
:
1848 if (!(clone_flags
& CLONE_THREAD
))
1849 free_signal_struct(p
->signal
);
1850 bad_fork_cleanup_sighand
:
1851 __cleanup_sighand(p
->sighand
);
1852 bad_fork_cleanup_fs
:
1853 exit_fs(p
); /* blocking */
1854 bad_fork_cleanup_files
:
1855 exit_files(p
); /* blocking */
1856 bad_fork_cleanup_semundo
:
1858 bad_fork_cleanup_audit
:
1860 bad_fork_cleanup_perf
:
1861 perf_event_free_task(p
);
1862 bad_fork_cleanup_policy
:
1864 mpol_put(p
->mempolicy
);
1865 bad_fork_cleanup_threadgroup_lock
:
1867 delayacct_tsk_free(p
);
1868 bad_fork_cleanup_count
:
1869 atomic_dec(&p
->cred
->user
->processes
);
1872 p
->state
= TASK_DEAD
;
1876 return ERR_PTR(retval
);
1879 static inline void init_idle_pids(struct pid_link
*links
)
1883 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1884 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1885 links
[type
].pid
= &init_struct_pid
;
1889 struct task_struct
*fork_idle(int cpu
)
1891 struct task_struct
*task
;
1892 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0, 0,
1894 if (!IS_ERR(task
)) {
1895 init_idle_pids(task
->pids
);
1896 init_idle(task
, cpu
);
1903 * Ok, this is the main fork-routine.
1905 * It copies the process, and if successful kick-starts
1906 * it and waits for it to finish using the VM if required.
1908 long _do_fork(unsigned long clone_flags
,
1909 unsigned long stack_start
,
1910 unsigned long stack_size
,
1911 int __user
*parent_tidptr
,
1912 int __user
*child_tidptr
,
1915 struct task_struct
*p
;
1920 * Determine whether and which event to report to ptracer. When
1921 * called from kernel_thread or CLONE_UNTRACED is explicitly
1922 * requested, no event is reported; otherwise, report if the event
1923 * for the type of forking is enabled.
1925 if (!(clone_flags
& CLONE_UNTRACED
)) {
1926 if (clone_flags
& CLONE_VFORK
)
1927 trace
= PTRACE_EVENT_VFORK
;
1928 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1929 trace
= PTRACE_EVENT_CLONE
;
1931 trace
= PTRACE_EVENT_FORK
;
1933 if (likely(!ptrace_event_enabled(current
, trace
)))
1937 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1938 child_tidptr
, NULL
, trace
, tls
, NUMA_NO_NODE
);
1939 add_latent_entropy();
1941 * Do this prior waking up the new thread - the thread pointer
1942 * might get invalid after that point, if the thread exits quickly.
1945 struct completion vfork
;
1948 trace_sched_process_fork(current
, p
);
1950 pid
= get_task_pid(p
, PIDTYPE_PID
);
1953 if (clone_flags
& CLONE_PARENT_SETTID
)
1954 put_user(nr
, parent_tidptr
);
1956 if (clone_flags
& CLONE_VFORK
) {
1957 p
->vfork_done
= &vfork
;
1958 init_completion(&vfork
);
1962 wake_up_new_task(p
);
1964 /* forking complete and child started to run, tell ptracer */
1965 if (unlikely(trace
))
1966 ptrace_event_pid(trace
, pid
);
1968 if (clone_flags
& CLONE_VFORK
) {
1969 if (!wait_for_vfork_done(p
, &vfork
))
1970 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
1980 #ifndef CONFIG_HAVE_COPY_THREAD_TLS
1981 /* For compatibility with architectures that call do_fork directly rather than
1982 * using the syscall entry points below. */
1983 long do_fork(unsigned long clone_flags
,
1984 unsigned long stack_start
,
1985 unsigned long stack_size
,
1986 int __user
*parent_tidptr
,
1987 int __user
*child_tidptr
)
1989 return _do_fork(clone_flags
, stack_start
, stack_size
,
1990 parent_tidptr
, child_tidptr
, 0);
1995 * Create a kernel thread.
1997 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
1999 return _do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
2000 (unsigned long)arg
, NULL
, NULL
, 0);
2003 #ifdef __ARCH_WANT_SYS_FORK
2004 SYSCALL_DEFINE0(fork
)
2007 return _do_fork(SIGCHLD
, 0, 0, NULL
, NULL
, 0);
2009 /* can not support in nommu mode */
2015 #ifdef __ARCH_WANT_SYS_VFORK
2016 SYSCALL_DEFINE0(vfork
)
2018 return _do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
2023 #ifdef __ARCH_WANT_SYS_CLONE
2024 #ifdef CONFIG_CLONE_BACKWARDS
2025 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2026 int __user
*, parent_tidptr
,
2028 int __user
*, child_tidptr
)
2029 #elif defined(CONFIG_CLONE_BACKWARDS2)
2030 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
2031 int __user
*, parent_tidptr
,
2032 int __user
*, child_tidptr
,
2034 #elif defined(CONFIG_CLONE_BACKWARDS3)
2035 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2037 int __user
*, parent_tidptr
,
2038 int __user
*, child_tidptr
,
2041 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
2042 int __user
*, parent_tidptr
,
2043 int __user
*, child_tidptr
,
2047 return _do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
, tls
);
2051 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
2052 #define ARCH_MIN_MMSTRUCT_ALIGN 0
2055 static void sighand_ctor(void *data
)
2057 struct sighand_struct
*sighand
= data
;
2059 spin_lock_init(&sighand
->siglock
);
2060 init_waitqueue_head(&sighand
->signalfd_wqh
);
2063 void __init
proc_caches_init(void)
2065 sighand_cachep
= kmem_cache_create("sighand_cache",
2066 sizeof(struct sighand_struct
), 0,
2067 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
2068 SLAB_NOTRACK
|SLAB_ACCOUNT
, sighand_ctor
);
2069 signal_cachep
= kmem_cache_create("signal_cache",
2070 sizeof(struct signal_struct
), 0,
2071 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2073 files_cachep
= kmem_cache_create("files_cache",
2074 sizeof(struct files_struct
), 0,
2075 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2077 fs_cachep
= kmem_cache_create("fs_cache",
2078 sizeof(struct fs_struct
), 0,
2079 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2082 * FIXME! The "sizeof(struct mm_struct)" currently includes the
2083 * whole struct cpumask for the OFFSTACK case. We could change
2084 * this to *only* allocate as much of it as required by the
2085 * maximum number of CPU's we can ever have. The cpumask_allocation
2086 * is at the end of the structure, exactly for that reason.
2088 mm_cachep
= kmem_cache_create("mm_struct",
2089 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
2090 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
|SLAB_ACCOUNT
,
2092 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
|SLAB_ACCOUNT
);
2094 nsproxy_cache_init();
2098 * Check constraints on flags passed to the unshare system call.
2100 static int check_unshare_flags(unsigned long unshare_flags
)
2102 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
2103 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
2104 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
2105 CLONE_NEWUSER
|CLONE_NEWPID
|CLONE_NEWCGROUP
))
2108 * Not implemented, but pretend it works if there is nothing
2109 * to unshare. Note that unsharing the address space or the
2110 * signal handlers also need to unshare the signal queues (aka
2113 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
2114 if (!thread_group_empty(current
))
2117 if (unshare_flags
& (CLONE_SIGHAND
| CLONE_VM
)) {
2118 if (atomic_read(¤t
->sighand
->count
) > 1)
2121 if (unshare_flags
& CLONE_VM
) {
2122 if (!current_is_single_threaded())
2130 * Unshare the filesystem structure if it is being shared
2132 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
2134 struct fs_struct
*fs
= current
->fs
;
2136 if (!(unshare_flags
& CLONE_FS
) || !fs
)
2139 /* don't need lock here; in the worst case we'll do useless copy */
2143 *new_fsp
= copy_fs_struct(fs
);
2151 * Unshare file descriptor table if it is being shared
2153 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
2155 struct files_struct
*fd
= current
->files
;
2158 if ((unshare_flags
& CLONE_FILES
) &&
2159 (fd
&& atomic_read(&fd
->count
) > 1)) {
2160 *new_fdp
= dup_fd(fd
, &error
);
2169 * unshare allows a process to 'unshare' part of the process
2170 * context which was originally shared using clone. copy_*
2171 * functions used by do_fork() cannot be used here directly
2172 * because they modify an inactive task_struct that is being
2173 * constructed. Here we are modifying the current, active,
2176 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
2178 struct fs_struct
*fs
, *new_fs
= NULL
;
2179 struct files_struct
*fd
, *new_fd
= NULL
;
2180 struct cred
*new_cred
= NULL
;
2181 struct nsproxy
*new_nsproxy
= NULL
;
2186 * If unsharing a user namespace must also unshare the thread group
2187 * and unshare the filesystem root and working directories.
2189 if (unshare_flags
& CLONE_NEWUSER
)
2190 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
2192 * If unsharing vm, must also unshare signal handlers.
2194 if (unshare_flags
& CLONE_VM
)
2195 unshare_flags
|= CLONE_SIGHAND
;
2197 * If unsharing a signal handlers, must also unshare the signal queues.
2199 if (unshare_flags
& CLONE_SIGHAND
)
2200 unshare_flags
|= CLONE_THREAD
;
2202 * If unsharing namespace, must also unshare filesystem information.
2204 if (unshare_flags
& CLONE_NEWNS
)
2205 unshare_flags
|= CLONE_FS
;
2207 err
= check_unshare_flags(unshare_flags
);
2209 goto bad_unshare_out
;
2211 * CLONE_NEWIPC must also detach from the undolist: after switching
2212 * to a new ipc namespace, the semaphore arrays from the old
2213 * namespace are unreachable.
2215 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
2217 err
= unshare_fs(unshare_flags
, &new_fs
);
2219 goto bad_unshare_out
;
2220 err
= unshare_fd(unshare_flags
, &new_fd
);
2222 goto bad_unshare_cleanup_fs
;
2223 err
= unshare_userns(unshare_flags
, &new_cred
);
2225 goto bad_unshare_cleanup_fd
;
2226 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
2229 goto bad_unshare_cleanup_cred
;
2231 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
2234 * CLONE_SYSVSEM is equivalent to sys_exit().
2238 if (unshare_flags
& CLONE_NEWIPC
) {
2239 /* Orphan segments in old ns (see sem above). */
2241 shm_init_task(current
);
2245 switch_task_namespaces(current
, new_nsproxy
);
2251 spin_lock(&fs
->lock
);
2252 current
->fs
= new_fs
;
2257 spin_unlock(&fs
->lock
);
2261 fd
= current
->files
;
2262 current
->files
= new_fd
;
2266 task_unlock(current
);
2269 /* Install the new user namespace */
2270 commit_creds(new_cred
);
2275 bad_unshare_cleanup_cred
:
2278 bad_unshare_cleanup_fd
:
2280 put_files_struct(new_fd
);
2282 bad_unshare_cleanup_fs
:
2284 free_fs_struct(new_fs
);
2291 * Helper to unshare the files of the current task.
2292 * We don't want to expose copy_files internals to
2293 * the exec layer of the kernel.
2296 int unshare_files(struct files_struct
**displaced
)
2298 struct task_struct
*task
= current
;
2299 struct files_struct
*copy
= NULL
;
2302 error
= unshare_fd(CLONE_FILES
, ©
);
2303 if (error
|| !copy
) {
2307 *displaced
= task
->files
;
2314 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2315 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2319 int threads
= max_threads
;
2320 int min
= MIN_THREADS
;
2321 int max
= MAX_THREADS
;
2328 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2332 set_max_threads(threads
);