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>
79 #include <asm/pgtable.h>
80 #include <asm/pgalloc.h>
81 #include <asm/uaccess.h>
82 #include <asm/mmu_context.h>
83 #include <asm/cacheflush.h>
84 #include <asm/tlbflush.h>
86 #include <trace/events/sched.h>
88 #define CREATE_TRACE_POINTS
89 #include <trace/events/task.h>
92 * Minimum number of threads to boot the kernel
94 #define MIN_THREADS 20
97 * Maximum number of threads
99 #define MAX_THREADS FUTEX_TID_MASK
102 * Protected counters by write_lock_irq(&tasklist_lock)
104 unsigned long total_forks
; /* Handle normal Linux uptimes. */
105 int nr_threads
; /* The idle threads do not count.. */
107 int max_threads
; /* tunable limit on nr_threads */
109 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
111 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
113 #ifdef CONFIG_PROVE_RCU
114 int lockdep_tasklist_lock_is_held(void)
116 return lockdep_is_held(&tasklist_lock
);
118 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
119 #endif /* #ifdef CONFIG_PROVE_RCU */
121 int nr_processes(void)
126 for_each_possible_cpu(cpu
)
127 total
+= per_cpu(process_counts
, cpu
);
132 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
136 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
137 static struct kmem_cache
*task_struct_cachep
;
139 static inline struct task_struct
*alloc_task_struct_node(int node
)
141 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
144 static inline void free_task_struct(struct task_struct
*tsk
)
146 kmem_cache_free(task_struct_cachep
, tsk
);
150 void __weak
arch_release_thread_info(struct thread_info
*ti
)
154 #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR
157 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
158 * kmemcache based allocator.
160 # if THREAD_SIZE >= PAGE_SIZE
161 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
164 struct page
*page
= alloc_kmem_pages_node(node
, THREADINFO_GFP
,
167 return page
? page_address(page
) : NULL
;
170 static inline void free_thread_info(struct thread_info
*ti
)
172 free_kmem_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
175 static struct kmem_cache
*thread_info_cache
;
177 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
180 return kmem_cache_alloc_node(thread_info_cache
, THREADINFO_GFP
, node
);
183 static void free_thread_info(struct thread_info
*ti
)
185 kmem_cache_free(thread_info_cache
, ti
);
188 void thread_info_cache_init(void)
190 thread_info_cache
= kmem_cache_create("thread_info", THREAD_SIZE
,
191 THREAD_SIZE
, 0, NULL
);
192 BUG_ON(thread_info_cache
== NULL
);
197 /* SLAB cache for signal_struct structures (tsk->signal) */
198 static struct kmem_cache
*signal_cachep
;
200 /* SLAB cache for sighand_struct structures (tsk->sighand) */
201 struct kmem_cache
*sighand_cachep
;
203 /* SLAB cache for files_struct structures (tsk->files) */
204 struct kmem_cache
*files_cachep
;
206 /* SLAB cache for fs_struct structures (tsk->fs) */
207 struct kmem_cache
*fs_cachep
;
209 /* SLAB cache for vm_area_struct structures */
210 struct kmem_cache
*vm_area_cachep
;
212 /* SLAB cache for mm_struct structures (tsk->mm) */
213 static struct kmem_cache
*mm_cachep
;
215 static void account_kernel_stack(struct thread_info
*ti
, int account
)
217 struct zone
*zone
= page_zone(virt_to_page(ti
));
219 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
222 void free_task(struct task_struct
*tsk
)
224 account_kernel_stack(tsk
->stack
, -1);
225 arch_release_thread_info(tsk
->stack
);
226 free_thread_info(tsk
->stack
);
227 rt_mutex_debug_task_free(tsk
);
228 ftrace_graph_exit_task(tsk
);
229 put_seccomp_filter(tsk
);
230 arch_release_task_struct(tsk
);
231 free_task_struct(tsk
);
233 EXPORT_SYMBOL(free_task
);
235 static inline void free_signal_struct(struct signal_struct
*sig
)
237 taskstats_tgid_free(sig
);
238 sched_autogroup_exit(sig
);
239 kmem_cache_free(signal_cachep
, sig
);
242 static inline void put_signal_struct(struct signal_struct
*sig
)
244 if (atomic_dec_and_test(&sig
->sigcnt
))
245 free_signal_struct(sig
);
248 void __put_task_struct(struct task_struct
*tsk
)
250 WARN_ON(!tsk
->exit_state
);
251 WARN_ON(atomic_read(&tsk
->usage
));
252 WARN_ON(tsk
== current
);
255 security_task_free(tsk
);
257 delayacct_tsk_free(tsk
);
258 put_signal_struct(tsk
->signal
);
260 if (!profile_handoff_task(tsk
))
263 EXPORT_SYMBOL_GPL(__put_task_struct
);
265 void __init __weak
arch_task_cache_init(void) { }
270 static void set_max_threads(unsigned int max_threads_suggested
)
275 * The number of threads shall be limited such that the thread
276 * structures may only consume a small part of the available memory.
278 if (fls64(totalram_pages
) + fls64(PAGE_SIZE
) > 64)
279 threads
= MAX_THREADS
;
281 threads
= div64_u64((u64
) totalram_pages
* (u64
) PAGE_SIZE
,
282 (u64
) THREAD_SIZE
* 8UL);
284 if (threads
> max_threads_suggested
)
285 threads
= max_threads_suggested
;
287 max_threads
= clamp_t(u64
, threads
, MIN_THREADS
, MAX_THREADS
);
290 void __init
fork_init(void)
292 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
293 #ifndef ARCH_MIN_TASKALIGN
294 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
296 /* create a slab on which task_structs can be allocated */
298 kmem_cache_create("task_struct", sizeof(struct task_struct
),
299 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
302 /* do the arch specific task caches init */
303 arch_task_cache_init();
305 set_max_threads(MAX_THREADS
);
307 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
308 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
309 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
310 init_task
.signal
->rlim
[RLIMIT_NPROC
];
313 int __weak
arch_dup_task_struct(struct task_struct
*dst
,
314 struct task_struct
*src
)
320 void set_task_stack_end_magic(struct task_struct
*tsk
)
322 unsigned long *stackend
;
324 stackend
= end_of_stack(tsk
);
325 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
328 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
330 struct task_struct
*tsk
;
331 struct thread_info
*ti
;
332 int node
= tsk_fork_get_node(orig
);
335 tsk
= alloc_task_struct_node(node
);
339 ti
= alloc_thread_info_node(tsk
, node
);
343 err
= arch_dup_task_struct(tsk
, orig
);
348 #ifdef CONFIG_SECCOMP
350 * We must handle setting up seccomp filters once we're under
351 * the sighand lock in case orig has changed between now and
352 * then. Until then, filter must be NULL to avoid messing up
353 * the usage counts on the error path calling free_task.
355 tsk
->seccomp
.filter
= NULL
;
358 setup_thread_stack(tsk
, orig
);
359 clear_user_return_notifier(tsk
);
360 clear_tsk_need_resched(tsk
);
361 set_task_stack_end_magic(tsk
);
363 #ifdef CONFIG_CC_STACKPROTECTOR
364 tsk
->stack_canary
= get_random_int();
368 * One for us, one for whoever does the "release_task()" (usually
371 atomic_set(&tsk
->usage
, 2);
372 #ifdef CONFIG_BLK_DEV_IO_TRACE
375 tsk
->splice_pipe
= NULL
;
376 tsk
->task_frag
.page
= NULL
;
378 account_kernel_stack(ti
, 1);
383 free_thread_info(ti
);
385 free_task_struct(tsk
);
390 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
392 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
393 struct rb_node
**rb_link
, *rb_parent
;
395 unsigned long charge
;
397 uprobe_start_dup_mmap();
398 down_write(&oldmm
->mmap_sem
);
399 flush_cache_dup_mm(oldmm
);
400 uprobe_dup_mmap(oldmm
, mm
);
402 * Not linked in yet - no deadlock potential:
404 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
406 /* No ordering required: file already has been exposed. */
407 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
409 mm
->total_vm
= oldmm
->total_vm
;
410 mm
->shared_vm
= oldmm
->shared_vm
;
411 mm
->exec_vm
= oldmm
->exec_vm
;
412 mm
->stack_vm
= oldmm
->stack_vm
;
414 rb_link
= &mm
->mm_rb
.rb_node
;
417 retval
= ksm_fork(mm
, oldmm
);
420 retval
= khugepaged_fork(mm
, oldmm
);
425 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
428 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
429 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
434 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
435 unsigned long len
= vma_pages(mpnt
);
437 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
441 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
445 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
446 retval
= vma_dup_policy(mpnt
, tmp
);
448 goto fail_nomem_policy
;
450 if (anon_vma_fork(tmp
, mpnt
))
451 goto fail_nomem_anon_vma_fork
;
452 tmp
->vm_flags
&= ~VM_LOCKED
;
453 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
456 struct inode
*inode
= file_inode(file
);
457 struct address_space
*mapping
= file
->f_mapping
;
460 if (tmp
->vm_flags
& VM_DENYWRITE
)
461 atomic_dec(&inode
->i_writecount
);
462 i_mmap_lock_write(mapping
);
463 if (tmp
->vm_flags
& VM_SHARED
)
464 atomic_inc(&mapping
->i_mmap_writable
);
465 flush_dcache_mmap_lock(mapping
);
466 /* insert tmp into the share list, just after mpnt */
467 vma_interval_tree_insert_after(tmp
, mpnt
,
469 flush_dcache_mmap_unlock(mapping
);
470 i_mmap_unlock_write(mapping
);
474 * Clear hugetlb-related page reserves for children. This only
475 * affects MAP_PRIVATE mappings. Faults generated by the child
476 * are not guaranteed to succeed, even if read-only
478 if (is_vm_hugetlb_page(tmp
))
479 reset_vma_resv_huge_pages(tmp
);
482 * Link in the new vma and copy the page table entries.
485 pprev
= &tmp
->vm_next
;
489 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
490 rb_link
= &tmp
->vm_rb
.rb_right
;
491 rb_parent
= &tmp
->vm_rb
;
494 retval
= copy_page_range(mm
, oldmm
, mpnt
);
496 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
497 tmp
->vm_ops
->open(tmp
);
502 /* a new mm has just been created */
503 arch_dup_mmap(oldmm
, mm
);
506 up_write(&mm
->mmap_sem
);
508 up_write(&oldmm
->mmap_sem
);
509 uprobe_end_dup_mmap();
511 fail_nomem_anon_vma_fork
:
512 mpol_put(vma_policy(tmp
));
514 kmem_cache_free(vm_area_cachep
, tmp
);
517 vm_unacct_memory(charge
);
521 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
523 mm
->pgd
= pgd_alloc(mm
);
524 if (unlikely(!mm
->pgd
))
529 static inline void mm_free_pgd(struct mm_struct
*mm
)
531 pgd_free(mm
, mm
->pgd
);
534 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
536 down_write(&oldmm
->mmap_sem
);
537 RCU_INIT_POINTER(mm
->exe_file
, get_mm_exe_file(oldmm
));
538 up_write(&oldmm
->mmap_sem
);
541 #define mm_alloc_pgd(mm) (0)
542 #define mm_free_pgd(mm)
543 #endif /* CONFIG_MMU */
545 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
547 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
548 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
550 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
552 static int __init
coredump_filter_setup(char *s
)
554 default_dump_filter
=
555 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
556 MMF_DUMP_FILTER_MASK
;
560 __setup("coredump_filter=", coredump_filter_setup
);
562 #include <linux/init_task.h>
564 static void mm_init_aio(struct mm_struct
*mm
)
567 spin_lock_init(&mm
->ioctx_lock
);
568 mm
->ioctx_table
= NULL
;
572 static void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
579 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
)
583 mm
->vmacache_seqnum
= 0;
584 atomic_set(&mm
->mm_users
, 1);
585 atomic_set(&mm
->mm_count
, 1);
586 init_rwsem(&mm
->mmap_sem
);
587 INIT_LIST_HEAD(&mm
->mmlist
);
588 mm
->core_state
= NULL
;
589 atomic_long_set(&mm
->nr_ptes
, 0);
594 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
595 spin_lock_init(&mm
->page_table_lock
);
598 mm_init_owner(mm
, p
);
599 mmu_notifier_mm_init(mm
);
600 clear_tlb_flush_pending(mm
);
601 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
602 mm
->pmd_huge_pte
= NULL
;
606 mm
->flags
= current
->mm
->flags
& MMF_INIT_MASK
;
607 mm
->def_flags
= current
->mm
->def_flags
& VM_INIT_DEF_MASK
;
609 mm
->flags
= default_dump_filter
;
613 if (mm_alloc_pgd(mm
))
616 if (init_new_context(p
, mm
))
628 static void check_mm(struct mm_struct
*mm
)
632 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
633 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
636 printk(KERN_ALERT
"BUG: Bad rss-counter state "
637 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
640 if (atomic_long_read(&mm
->nr_ptes
))
641 pr_alert("BUG: non-zero nr_ptes on freeing mm: %ld\n",
642 atomic_long_read(&mm
->nr_ptes
));
644 pr_alert("BUG: non-zero nr_pmds on freeing mm: %ld\n",
647 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
648 VM_BUG_ON_MM(mm
->pmd_huge_pte
, mm
);
653 * Allocate and initialize an mm_struct.
655 struct mm_struct
*mm_alloc(void)
657 struct mm_struct
*mm
;
663 memset(mm
, 0, sizeof(*mm
));
664 return mm_init(mm
, current
);
668 * Called when the last reference to the mm
669 * is dropped: either by a lazy thread or by
670 * mmput. Free the page directory and the mm.
672 void __mmdrop(struct mm_struct
*mm
)
674 BUG_ON(mm
== &init_mm
);
677 mmu_notifier_mm_destroy(mm
);
681 EXPORT_SYMBOL_GPL(__mmdrop
);
684 * Decrement the use count and release all resources for an mm.
686 void mmput(struct mm_struct
*mm
)
690 if (atomic_dec_and_test(&mm
->mm_users
)) {
691 uprobe_clear_state(mm
);
694 khugepaged_exit(mm
); /* must run before exit_mmap */
696 set_mm_exe_file(mm
, NULL
);
697 if (!list_empty(&mm
->mmlist
)) {
698 spin_lock(&mmlist_lock
);
699 list_del(&mm
->mmlist
);
700 spin_unlock(&mmlist_lock
);
703 module_put(mm
->binfmt
->module
);
707 EXPORT_SYMBOL_GPL(mmput
);
710 * set_mm_exe_file - change a reference to the mm's executable file
712 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
714 * Main users are mmput(), sys_execve() and sys_prctl(PR_SET_MM_MAP/EXE_FILE).
715 * Callers prevent concurrent invocations: in mmput() nobody alive left,
716 * in execve task is single-threaded, prctl holds mmap_sem exclusively.
718 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
720 struct file
*old_exe_file
= rcu_dereference_protected(mm
->exe_file
,
721 !atomic_read(&mm
->mm_users
) || current
->in_execve
||
722 lockdep_is_held(&mm
->mmap_sem
));
725 get_file(new_exe_file
);
726 rcu_assign_pointer(mm
->exe_file
, new_exe_file
);
732 * get_mm_exe_file - acquire a reference to the mm's executable file
734 * Returns %NULL if mm has no associated executable file.
735 * User must release file via fput().
737 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
739 struct file
*exe_file
;
742 exe_file
= rcu_dereference(mm
->exe_file
);
743 if (exe_file
&& !get_file_rcu(exe_file
))
750 * get_task_mm - acquire a reference to the task's mm
752 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
753 * this kernel workthread has transiently adopted a user mm with use_mm,
754 * to do its AIO) is not set and if so returns a reference to it, after
755 * bumping up the use count. User must release the mm via mmput()
756 * after use. Typically used by /proc and ptrace.
758 struct mm_struct
*get_task_mm(struct task_struct
*task
)
760 struct mm_struct
*mm
;
765 if (task
->flags
& PF_KTHREAD
)
768 atomic_inc(&mm
->mm_users
);
773 EXPORT_SYMBOL_GPL(get_task_mm
);
775 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
777 struct mm_struct
*mm
;
780 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
784 mm
= get_task_mm(task
);
785 if (mm
&& mm
!= current
->mm
&&
786 !ptrace_may_access(task
, mode
)) {
788 mm
= ERR_PTR(-EACCES
);
790 mutex_unlock(&task
->signal
->cred_guard_mutex
);
795 static void complete_vfork_done(struct task_struct
*tsk
)
797 struct completion
*vfork
;
800 vfork
= tsk
->vfork_done
;
802 tsk
->vfork_done
= NULL
;
808 static int wait_for_vfork_done(struct task_struct
*child
,
809 struct completion
*vfork
)
813 freezer_do_not_count();
814 killed
= wait_for_completion_killable(vfork
);
819 child
->vfork_done
= NULL
;
823 put_task_struct(child
);
827 /* Please note the differences between mmput and mm_release.
828 * mmput is called whenever we stop holding onto a mm_struct,
829 * error success whatever.
831 * mm_release is called after a mm_struct has been removed
832 * from the current process.
834 * This difference is important for error handling, when we
835 * only half set up a mm_struct for a new process and need to restore
836 * the old one. Because we mmput the new mm_struct before
837 * restoring the old one. . .
838 * Eric Biederman 10 January 1998
840 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
842 /* Get rid of any futexes when releasing the mm */
844 if (unlikely(tsk
->robust_list
)) {
845 exit_robust_list(tsk
);
846 tsk
->robust_list
= NULL
;
849 if (unlikely(tsk
->compat_robust_list
)) {
850 compat_exit_robust_list(tsk
);
851 tsk
->compat_robust_list
= NULL
;
854 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
855 exit_pi_state_list(tsk
);
858 uprobe_free_utask(tsk
);
860 /* Get rid of any cached register state */
861 deactivate_mm(tsk
, mm
);
864 * If we're exiting normally, clear a user-space tid field if
865 * requested. We leave this alone when dying by signal, to leave
866 * the value intact in a core dump, and to save the unnecessary
867 * trouble, say, a killed vfork parent shouldn't touch this mm.
868 * Userland only wants this done for a sys_exit.
870 if (tsk
->clear_child_tid
) {
871 if (!(tsk
->flags
& PF_SIGNALED
) &&
872 atomic_read(&mm
->mm_users
) > 1) {
874 * We don't check the error code - if userspace has
875 * not set up a proper pointer then tough luck.
877 put_user(0, tsk
->clear_child_tid
);
878 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
881 tsk
->clear_child_tid
= NULL
;
885 * All done, finally we can wake up parent and return this mm to him.
886 * Also kthread_stop() uses this completion for synchronization.
889 complete_vfork_done(tsk
);
893 * Allocate a new mm structure and copy contents from the
894 * mm structure of the passed in task structure.
896 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
898 struct mm_struct
*mm
, *oldmm
= current
->mm
;
905 memcpy(mm
, oldmm
, sizeof(*mm
));
907 if (!mm_init(mm
, tsk
))
910 err
= dup_mmap(mm
, oldmm
);
914 mm
->hiwater_rss
= get_mm_rss(mm
);
915 mm
->hiwater_vm
= mm
->total_vm
;
917 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
923 /* don't put binfmt in mmput, we haven't got module yet */
931 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
933 struct mm_struct
*mm
, *oldmm
;
936 tsk
->min_flt
= tsk
->maj_flt
= 0;
937 tsk
->nvcsw
= tsk
->nivcsw
= 0;
938 #ifdef CONFIG_DETECT_HUNG_TASK
939 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
943 tsk
->active_mm
= NULL
;
946 * Are we cloning a kernel thread?
948 * We need to steal a active VM for that..
954 /* initialize the new vmacache entries */
957 if (clone_flags
& CLONE_VM
) {
958 atomic_inc(&oldmm
->mm_users
);
977 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
979 struct fs_struct
*fs
= current
->fs
;
980 if (clone_flags
& CLONE_FS
) {
981 /* tsk->fs is already what we want */
982 spin_lock(&fs
->lock
);
984 spin_unlock(&fs
->lock
);
988 spin_unlock(&fs
->lock
);
991 tsk
->fs
= copy_fs_struct(fs
);
997 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
999 struct files_struct
*oldf
, *newf
;
1003 * A background process may not have any files ...
1005 oldf
= current
->files
;
1009 if (clone_flags
& CLONE_FILES
) {
1010 atomic_inc(&oldf
->count
);
1014 newf
= dup_fd(oldf
, &error
);
1024 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
1027 struct io_context
*ioc
= current
->io_context
;
1028 struct io_context
*new_ioc
;
1033 * Share io context with parent, if CLONE_IO is set
1035 if (clone_flags
& CLONE_IO
) {
1037 tsk
->io_context
= ioc
;
1038 } else if (ioprio_valid(ioc
->ioprio
)) {
1039 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
1040 if (unlikely(!new_ioc
))
1043 new_ioc
->ioprio
= ioc
->ioprio
;
1044 put_io_context(new_ioc
);
1050 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
1052 struct sighand_struct
*sig
;
1054 if (clone_flags
& CLONE_SIGHAND
) {
1055 atomic_inc(¤t
->sighand
->count
);
1058 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
1059 rcu_assign_pointer(tsk
->sighand
, sig
);
1062 atomic_set(&sig
->count
, 1);
1063 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
1067 void __cleanup_sighand(struct sighand_struct
*sighand
)
1069 if (atomic_dec_and_test(&sighand
->count
)) {
1070 signalfd_cleanup(sighand
);
1072 * sighand_cachep is SLAB_DESTROY_BY_RCU so we can free it
1073 * without an RCU grace period, see __lock_task_sighand().
1075 kmem_cache_free(sighand_cachep
, sighand
);
1080 * Initialize POSIX timer handling for a thread group.
1082 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1084 unsigned long cpu_limit
;
1086 /* Thread group counters. */
1087 thread_group_cputime_init(sig
);
1089 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1090 if (cpu_limit
!= RLIM_INFINITY
) {
1091 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1092 sig
->cputimer
.running
= 1;
1095 /* The timer lists. */
1096 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1097 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1098 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1101 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1103 struct signal_struct
*sig
;
1105 if (clone_flags
& CLONE_THREAD
)
1108 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1113 sig
->nr_threads
= 1;
1114 atomic_set(&sig
->live
, 1);
1115 atomic_set(&sig
->sigcnt
, 1);
1117 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1118 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1119 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1121 init_waitqueue_head(&sig
->wait_chldexit
);
1122 sig
->curr_target
= tsk
;
1123 init_sigpending(&sig
->shared_pending
);
1124 INIT_LIST_HEAD(&sig
->posix_timers
);
1125 seqlock_init(&sig
->stats_lock
);
1127 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1128 sig
->real_timer
.function
= it_real_fn
;
1130 task_lock(current
->group_leader
);
1131 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1132 task_unlock(current
->group_leader
);
1134 posix_cpu_timers_init_group(sig
);
1136 tty_audit_fork(sig
);
1137 sched_autogroup_fork(sig
);
1139 #ifdef CONFIG_CGROUPS
1140 init_rwsem(&sig
->group_rwsem
);
1143 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1144 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1146 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1147 current
->signal
->is_child_subreaper
;
1149 mutex_init(&sig
->cred_guard_mutex
);
1154 static void copy_seccomp(struct task_struct
*p
)
1156 #ifdef CONFIG_SECCOMP
1158 * Must be called with sighand->lock held, which is common to
1159 * all threads in the group. Holding cred_guard_mutex is not
1160 * needed because this new task is not yet running and cannot
1163 assert_spin_locked(¤t
->sighand
->siglock
);
1165 /* Ref-count the new filter user, and assign it. */
1166 get_seccomp_filter(current
);
1167 p
->seccomp
= current
->seccomp
;
1170 * Explicitly enable no_new_privs here in case it got set
1171 * between the task_struct being duplicated and holding the
1172 * sighand lock. The seccomp state and nnp must be in sync.
1174 if (task_no_new_privs(current
))
1175 task_set_no_new_privs(p
);
1178 * If the parent gained a seccomp mode after copying thread
1179 * flags and between before we held the sighand lock, we have
1180 * to manually enable the seccomp thread flag here.
1182 if (p
->seccomp
.mode
!= SECCOMP_MODE_DISABLED
)
1183 set_tsk_thread_flag(p
, TIF_SECCOMP
);
1187 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1189 current
->clear_child_tid
= tidptr
;
1191 return task_pid_vnr(current
);
1194 static void rt_mutex_init_task(struct task_struct
*p
)
1196 raw_spin_lock_init(&p
->pi_lock
);
1197 #ifdef CONFIG_RT_MUTEXES
1198 p
->pi_waiters
= RB_ROOT
;
1199 p
->pi_waiters_leftmost
= NULL
;
1200 p
->pi_blocked_on
= NULL
;
1205 * Initialize POSIX timer handling for a single task.
1207 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1209 tsk
->cputime_expires
.prof_exp
= 0;
1210 tsk
->cputime_expires
.virt_exp
= 0;
1211 tsk
->cputime_expires
.sched_exp
= 0;
1212 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1213 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1214 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1218 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1220 task
->pids
[type
].pid
= pid
;
1224 * This creates a new process as a copy of the old one,
1225 * but does not actually start it yet.
1227 * It copies the registers, and all the appropriate
1228 * parts of the process environment (as per the clone
1229 * flags). The actual kick-off is left to the caller.
1231 static struct task_struct
*copy_process(unsigned long clone_flags
,
1232 unsigned long stack_start
,
1233 unsigned long stack_size
,
1234 int __user
*child_tidptr
,
1239 struct task_struct
*p
;
1241 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1242 return ERR_PTR(-EINVAL
);
1244 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1245 return ERR_PTR(-EINVAL
);
1248 * Thread groups must share signals as well, and detached threads
1249 * can only be started up within the thread group.
1251 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1252 return ERR_PTR(-EINVAL
);
1255 * Shared signal handlers imply shared VM. By way of the above,
1256 * thread groups also imply shared VM. Blocking this case allows
1257 * for various simplifications in other code.
1259 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1260 return ERR_PTR(-EINVAL
);
1263 * Siblings of global init remain as zombies on exit since they are
1264 * not reaped by their parent (swapper). To solve this and to avoid
1265 * multi-rooted process trees, prevent global and container-inits
1266 * from creating siblings.
1268 if ((clone_flags
& CLONE_PARENT
) &&
1269 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1270 return ERR_PTR(-EINVAL
);
1273 * If the new process will be in a different pid or user namespace
1274 * do not allow it to share a thread group or signal handlers or
1275 * parent with the forking task.
1277 if (clone_flags
& CLONE_SIGHAND
) {
1278 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1279 (task_active_pid_ns(current
) !=
1280 current
->nsproxy
->pid_ns_for_children
))
1281 return ERR_PTR(-EINVAL
);
1284 retval
= security_task_create(clone_flags
);
1289 p
= dup_task_struct(current
);
1293 ftrace_graph_init_task(p
);
1295 rt_mutex_init_task(p
);
1297 #ifdef CONFIG_PROVE_LOCKING
1298 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1299 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1302 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1303 task_rlimit(p
, RLIMIT_NPROC
)) {
1304 if (p
->real_cred
->user
!= INIT_USER
&&
1305 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1308 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1310 retval
= copy_creds(p
, clone_flags
);
1315 * If multiple threads are within copy_process(), then this check
1316 * triggers too late. This doesn't hurt, the check is only there
1317 * to stop root fork bombs.
1320 if (nr_threads
>= max_threads
)
1321 goto bad_fork_cleanup_count
;
1323 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1324 p
->flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
1325 p
->flags
|= PF_FORKNOEXEC
;
1326 INIT_LIST_HEAD(&p
->children
);
1327 INIT_LIST_HEAD(&p
->sibling
);
1328 rcu_copy_process(p
);
1329 p
->vfork_done
= NULL
;
1330 spin_lock_init(&p
->alloc_lock
);
1332 init_sigpending(&p
->pending
);
1334 p
->utime
= p
->stime
= p
->gtime
= 0;
1335 p
->utimescaled
= p
->stimescaled
= 0;
1336 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
1337 p
->prev_cputime
.utime
= p
->prev_cputime
.stime
= 0;
1339 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1340 seqlock_init(&p
->vtime_seqlock
);
1342 p
->vtime_snap_whence
= VTIME_SLEEPING
;
1345 #if defined(SPLIT_RSS_COUNTING)
1346 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1349 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1351 task_io_accounting_init(&p
->ioac
);
1352 acct_clear_integrals(p
);
1354 posix_cpu_timers_init(p
);
1356 p
->start_time
= ktime_get_ns();
1357 p
->real_start_time
= ktime_get_boot_ns();
1358 p
->io_context
= NULL
;
1359 p
->audit_context
= NULL
;
1360 if (clone_flags
& CLONE_THREAD
)
1361 threadgroup_change_begin(current
);
1364 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1365 if (IS_ERR(p
->mempolicy
)) {
1366 retval
= PTR_ERR(p
->mempolicy
);
1367 p
->mempolicy
= NULL
;
1368 goto bad_fork_cleanup_threadgroup_lock
;
1371 #ifdef CONFIG_CPUSETS
1372 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1373 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1374 seqcount_init(&p
->mems_allowed_seq
);
1376 #ifdef CONFIG_TRACE_IRQFLAGS
1378 p
->hardirqs_enabled
= 0;
1379 p
->hardirq_enable_ip
= 0;
1380 p
->hardirq_enable_event
= 0;
1381 p
->hardirq_disable_ip
= _THIS_IP_
;
1382 p
->hardirq_disable_event
= 0;
1383 p
->softirqs_enabled
= 1;
1384 p
->softirq_enable_ip
= _THIS_IP_
;
1385 p
->softirq_enable_event
= 0;
1386 p
->softirq_disable_ip
= 0;
1387 p
->softirq_disable_event
= 0;
1388 p
->hardirq_context
= 0;
1389 p
->softirq_context
= 0;
1391 #ifdef CONFIG_LOCKDEP
1392 p
->lockdep_depth
= 0; /* no locks held yet */
1393 p
->curr_chain_key
= 0;
1394 p
->lockdep_recursion
= 0;
1397 #ifdef CONFIG_DEBUG_MUTEXES
1398 p
->blocked_on
= NULL
; /* not blocked yet */
1400 #ifdef CONFIG_BCACHE
1401 p
->sequential_io
= 0;
1402 p
->sequential_io_avg
= 0;
1405 /* Perform scheduler related setup. Assign this task to a CPU. */
1406 retval
= sched_fork(clone_flags
, p
);
1408 goto bad_fork_cleanup_policy
;
1410 retval
= perf_event_init_task(p
);
1412 goto bad_fork_cleanup_policy
;
1413 retval
= audit_alloc(p
);
1415 goto bad_fork_cleanup_perf
;
1416 /* copy all the process information */
1418 retval
= copy_semundo(clone_flags
, p
);
1420 goto bad_fork_cleanup_audit
;
1421 retval
= copy_files(clone_flags
, p
);
1423 goto bad_fork_cleanup_semundo
;
1424 retval
= copy_fs(clone_flags
, p
);
1426 goto bad_fork_cleanup_files
;
1427 retval
= copy_sighand(clone_flags
, p
);
1429 goto bad_fork_cleanup_fs
;
1430 retval
= copy_signal(clone_flags
, p
);
1432 goto bad_fork_cleanup_sighand
;
1433 retval
= copy_mm(clone_flags
, p
);
1435 goto bad_fork_cleanup_signal
;
1436 retval
= copy_namespaces(clone_flags
, p
);
1438 goto bad_fork_cleanup_mm
;
1439 retval
= copy_io(clone_flags
, p
);
1441 goto bad_fork_cleanup_namespaces
;
1442 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
);
1444 goto bad_fork_cleanup_io
;
1446 if (pid
!= &init_struct_pid
) {
1447 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1449 retval
= PTR_ERR(pid
);
1450 goto bad_fork_cleanup_io
;
1454 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1456 * Clear TID on mm_release()?
1458 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1463 p
->robust_list
= NULL
;
1464 #ifdef CONFIG_COMPAT
1465 p
->compat_robust_list
= NULL
;
1467 INIT_LIST_HEAD(&p
->pi_state_list
);
1468 p
->pi_state_cache
= NULL
;
1471 * sigaltstack should be cleared when sharing the same VM
1473 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1474 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1477 * Syscall tracing and stepping should be turned off in the
1478 * child regardless of CLONE_PTRACE.
1480 user_disable_single_step(p
);
1481 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1482 #ifdef TIF_SYSCALL_EMU
1483 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1485 clear_all_latency_tracing(p
);
1487 /* ok, now we should be set up.. */
1488 p
->pid
= pid_nr(pid
);
1489 if (clone_flags
& CLONE_THREAD
) {
1490 p
->exit_signal
= -1;
1491 p
->group_leader
= current
->group_leader
;
1492 p
->tgid
= current
->tgid
;
1494 if (clone_flags
& CLONE_PARENT
)
1495 p
->exit_signal
= current
->group_leader
->exit_signal
;
1497 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1498 p
->group_leader
= p
;
1503 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1504 p
->dirty_paused_when
= 0;
1506 p
->pdeath_signal
= 0;
1507 INIT_LIST_HEAD(&p
->thread_group
);
1508 p
->task_works
= NULL
;
1511 * Make it visible to the rest of the system, but dont wake it up yet.
1512 * Need tasklist lock for parent etc handling!
1514 write_lock_irq(&tasklist_lock
);
1516 /* CLONE_PARENT re-uses the old parent */
1517 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1518 p
->real_parent
= current
->real_parent
;
1519 p
->parent_exec_id
= current
->parent_exec_id
;
1521 p
->real_parent
= current
;
1522 p
->parent_exec_id
= current
->self_exec_id
;
1525 spin_lock(¤t
->sighand
->siglock
);
1528 * Copy seccomp details explicitly here, in case they were changed
1529 * before holding sighand lock.
1534 * Process group and session signals need to be delivered to just the
1535 * parent before the fork or both the parent and the child after the
1536 * fork. Restart if a signal comes in before we add the new process to
1537 * it's process group.
1538 * A fatal signal pending means that current will exit, so the new
1539 * thread can't slip out of an OOM kill (or normal SIGKILL).
1541 recalc_sigpending();
1542 if (signal_pending(current
)) {
1543 spin_unlock(¤t
->sighand
->siglock
);
1544 write_unlock_irq(&tasklist_lock
);
1545 retval
= -ERESTARTNOINTR
;
1546 goto bad_fork_free_pid
;
1549 if (likely(p
->pid
)) {
1550 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1552 init_task_pid(p
, PIDTYPE_PID
, pid
);
1553 if (thread_group_leader(p
)) {
1554 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1555 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1557 if (is_child_reaper(pid
)) {
1558 ns_of_pid(pid
)->child_reaper
= p
;
1559 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1562 p
->signal
->leader_pid
= pid
;
1563 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1564 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1565 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1566 attach_pid(p
, PIDTYPE_PGID
);
1567 attach_pid(p
, PIDTYPE_SID
);
1568 __this_cpu_inc(process_counts
);
1570 current
->signal
->nr_threads
++;
1571 atomic_inc(¤t
->signal
->live
);
1572 atomic_inc(¤t
->signal
->sigcnt
);
1573 list_add_tail_rcu(&p
->thread_group
,
1574 &p
->group_leader
->thread_group
);
1575 list_add_tail_rcu(&p
->thread_node
,
1576 &p
->signal
->thread_head
);
1578 attach_pid(p
, PIDTYPE_PID
);
1583 spin_unlock(¤t
->sighand
->siglock
);
1584 syscall_tracepoint_update(p
);
1585 write_unlock_irq(&tasklist_lock
);
1587 proc_fork_connector(p
);
1588 cgroup_post_fork(p
);
1589 if (clone_flags
& CLONE_THREAD
)
1590 threadgroup_change_end(current
);
1593 trace_task_newtask(p
, clone_flags
);
1594 uprobe_copy_process(p
, clone_flags
);
1599 if (pid
!= &init_struct_pid
)
1601 bad_fork_cleanup_io
:
1604 bad_fork_cleanup_namespaces
:
1605 exit_task_namespaces(p
);
1606 bad_fork_cleanup_mm
:
1609 bad_fork_cleanup_signal
:
1610 if (!(clone_flags
& CLONE_THREAD
))
1611 free_signal_struct(p
->signal
);
1612 bad_fork_cleanup_sighand
:
1613 __cleanup_sighand(p
->sighand
);
1614 bad_fork_cleanup_fs
:
1615 exit_fs(p
); /* blocking */
1616 bad_fork_cleanup_files
:
1617 exit_files(p
); /* blocking */
1618 bad_fork_cleanup_semundo
:
1620 bad_fork_cleanup_audit
:
1622 bad_fork_cleanup_perf
:
1623 perf_event_free_task(p
);
1624 bad_fork_cleanup_policy
:
1626 mpol_put(p
->mempolicy
);
1627 bad_fork_cleanup_threadgroup_lock
:
1629 if (clone_flags
& CLONE_THREAD
)
1630 threadgroup_change_end(current
);
1631 delayacct_tsk_free(p
);
1632 bad_fork_cleanup_count
:
1633 atomic_dec(&p
->cred
->user
->processes
);
1638 return ERR_PTR(retval
);
1641 static inline void init_idle_pids(struct pid_link
*links
)
1645 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1646 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1647 links
[type
].pid
= &init_struct_pid
;
1651 struct task_struct
*fork_idle(int cpu
)
1653 struct task_struct
*task
;
1654 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0);
1655 if (!IS_ERR(task
)) {
1656 init_idle_pids(task
->pids
);
1657 init_idle(task
, cpu
);
1664 * Ok, this is the main fork-routine.
1666 * It copies the process, and if successful kick-starts
1667 * it and waits for it to finish using the VM if required.
1669 long do_fork(unsigned long clone_flags
,
1670 unsigned long stack_start
,
1671 unsigned long stack_size
,
1672 int __user
*parent_tidptr
,
1673 int __user
*child_tidptr
)
1675 struct task_struct
*p
;
1680 * Determine whether and which event to report to ptracer. When
1681 * called from kernel_thread or CLONE_UNTRACED is explicitly
1682 * requested, no event is reported; otherwise, report if the event
1683 * for the type of forking is enabled.
1685 if (!(clone_flags
& CLONE_UNTRACED
)) {
1686 if (clone_flags
& CLONE_VFORK
)
1687 trace
= PTRACE_EVENT_VFORK
;
1688 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1689 trace
= PTRACE_EVENT_CLONE
;
1691 trace
= PTRACE_EVENT_FORK
;
1693 if (likely(!ptrace_event_enabled(current
, trace
)))
1697 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1698 child_tidptr
, NULL
, trace
);
1700 * Do this prior waking up the new thread - the thread pointer
1701 * might get invalid after that point, if the thread exits quickly.
1704 struct completion vfork
;
1707 trace_sched_process_fork(current
, p
);
1709 pid
= get_task_pid(p
, PIDTYPE_PID
);
1712 if (clone_flags
& CLONE_PARENT_SETTID
)
1713 put_user(nr
, parent_tidptr
);
1715 if (clone_flags
& CLONE_VFORK
) {
1716 p
->vfork_done
= &vfork
;
1717 init_completion(&vfork
);
1721 wake_up_new_task(p
);
1723 /* forking complete and child started to run, tell ptracer */
1724 if (unlikely(trace
))
1725 ptrace_event_pid(trace
, pid
);
1727 if (clone_flags
& CLONE_VFORK
) {
1728 if (!wait_for_vfork_done(p
, &vfork
))
1729 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
1740 * Create a kernel thread.
1742 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
1744 return do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
1745 (unsigned long)arg
, NULL
, NULL
);
1748 #ifdef __ARCH_WANT_SYS_FORK
1749 SYSCALL_DEFINE0(fork
)
1752 return do_fork(SIGCHLD
, 0, 0, NULL
, NULL
);
1754 /* can not support in nommu mode */
1760 #ifdef __ARCH_WANT_SYS_VFORK
1761 SYSCALL_DEFINE0(vfork
)
1763 return do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
1768 #ifdef __ARCH_WANT_SYS_CLONE
1769 #ifdef CONFIG_CLONE_BACKWARDS
1770 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1771 int __user
*, parent_tidptr
,
1773 int __user
*, child_tidptr
)
1774 #elif defined(CONFIG_CLONE_BACKWARDS2)
1775 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
1776 int __user
*, parent_tidptr
,
1777 int __user
*, child_tidptr
,
1779 #elif defined(CONFIG_CLONE_BACKWARDS3)
1780 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1782 int __user
*, parent_tidptr
,
1783 int __user
*, child_tidptr
,
1786 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1787 int __user
*, parent_tidptr
,
1788 int __user
*, child_tidptr
,
1792 return do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
);
1796 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1797 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1800 static void sighand_ctor(void *data
)
1802 struct sighand_struct
*sighand
= data
;
1804 spin_lock_init(&sighand
->siglock
);
1805 init_waitqueue_head(&sighand
->signalfd_wqh
);
1808 void __init
proc_caches_init(void)
1810 sighand_cachep
= kmem_cache_create("sighand_cache",
1811 sizeof(struct sighand_struct
), 0,
1812 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1813 SLAB_NOTRACK
, sighand_ctor
);
1814 signal_cachep
= kmem_cache_create("signal_cache",
1815 sizeof(struct signal_struct
), 0,
1816 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1817 files_cachep
= kmem_cache_create("files_cache",
1818 sizeof(struct files_struct
), 0,
1819 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1820 fs_cachep
= kmem_cache_create("fs_cache",
1821 sizeof(struct fs_struct
), 0,
1822 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1824 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1825 * whole struct cpumask for the OFFSTACK case. We could change
1826 * this to *only* allocate as much of it as required by the
1827 * maximum number of CPU's we can ever have. The cpumask_allocation
1828 * is at the end of the structure, exactly for that reason.
1830 mm_cachep
= kmem_cache_create("mm_struct",
1831 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1832 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1833 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1835 nsproxy_cache_init();
1839 * Check constraints on flags passed to the unshare system call.
1841 static int check_unshare_flags(unsigned long unshare_flags
)
1843 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1844 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1845 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
1846 CLONE_NEWUSER
|CLONE_NEWPID
))
1849 * Not implemented, but pretend it works if there is nothing to
1850 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1851 * needs to unshare vm.
1853 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
1854 /* FIXME: get_task_mm() increments ->mm_users */
1855 if (atomic_read(¤t
->mm
->mm_users
) > 1)
1863 * Unshare the filesystem structure if it is being shared
1865 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1867 struct fs_struct
*fs
= current
->fs
;
1869 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1872 /* don't need lock here; in the worst case we'll do useless copy */
1876 *new_fsp
= copy_fs_struct(fs
);
1884 * Unshare file descriptor table if it is being shared
1886 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1888 struct files_struct
*fd
= current
->files
;
1891 if ((unshare_flags
& CLONE_FILES
) &&
1892 (fd
&& atomic_read(&fd
->count
) > 1)) {
1893 *new_fdp
= dup_fd(fd
, &error
);
1902 * unshare allows a process to 'unshare' part of the process
1903 * context which was originally shared using clone. copy_*
1904 * functions used by do_fork() cannot be used here directly
1905 * because they modify an inactive task_struct that is being
1906 * constructed. Here we are modifying the current, active,
1909 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1911 struct fs_struct
*fs
, *new_fs
= NULL
;
1912 struct files_struct
*fd
, *new_fd
= NULL
;
1913 struct cred
*new_cred
= NULL
;
1914 struct nsproxy
*new_nsproxy
= NULL
;
1919 * If unsharing a user namespace must also unshare the thread.
1921 if (unshare_flags
& CLONE_NEWUSER
)
1922 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
1924 * If unsharing a thread from a thread group, must also unshare vm.
1926 if (unshare_flags
& CLONE_THREAD
)
1927 unshare_flags
|= CLONE_VM
;
1929 * If unsharing vm, must also unshare signal handlers.
1931 if (unshare_flags
& CLONE_VM
)
1932 unshare_flags
|= CLONE_SIGHAND
;
1934 * If unsharing namespace, must also unshare filesystem information.
1936 if (unshare_flags
& CLONE_NEWNS
)
1937 unshare_flags
|= CLONE_FS
;
1939 err
= check_unshare_flags(unshare_flags
);
1941 goto bad_unshare_out
;
1943 * CLONE_NEWIPC must also detach from the undolist: after switching
1944 * to a new ipc namespace, the semaphore arrays from the old
1945 * namespace are unreachable.
1947 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1949 err
= unshare_fs(unshare_flags
, &new_fs
);
1951 goto bad_unshare_out
;
1952 err
= unshare_fd(unshare_flags
, &new_fd
);
1954 goto bad_unshare_cleanup_fs
;
1955 err
= unshare_userns(unshare_flags
, &new_cred
);
1957 goto bad_unshare_cleanup_fd
;
1958 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1961 goto bad_unshare_cleanup_cred
;
1963 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
1966 * CLONE_SYSVSEM is equivalent to sys_exit().
1970 if (unshare_flags
& CLONE_NEWIPC
) {
1971 /* Orphan segments in old ns (see sem above). */
1973 shm_init_task(current
);
1977 switch_task_namespaces(current
, new_nsproxy
);
1983 spin_lock(&fs
->lock
);
1984 current
->fs
= new_fs
;
1989 spin_unlock(&fs
->lock
);
1993 fd
= current
->files
;
1994 current
->files
= new_fd
;
1998 task_unlock(current
);
2001 /* Install the new user namespace */
2002 commit_creds(new_cred
);
2007 bad_unshare_cleanup_cred
:
2010 bad_unshare_cleanup_fd
:
2012 put_files_struct(new_fd
);
2014 bad_unshare_cleanup_fs
:
2016 free_fs_struct(new_fs
);
2023 * Helper to unshare the files of the current task.
2024 * We don't want to expose copy_files internals to
2025 * the exec layer of the kernel.
2028 int unshare_files(struct files_struct
**displaced
)
2030 struct task_struct
*task
= current
;
2031 struct files_struct
*copy
= NULL
;
2034 error
= unshare_fd(CLONE_FILES
, ©
);
2035 if (error
|| !copy
) {
2039 *displaced
= task
->files
;
2046 int sysctl_max_threads(struct ctl_table
*table
, int write
,
2047 void __user
*buffer
, size_t *lenp
, loff_t
*ppos
)
2051 int threads
= max_threads
;
2052 int min
= MIN_THREADS
;
2053 int max
= MAX_THREADS
;
2060 ret
= proc_dointvec_minmax(&t
, write
, buffer
, lenp
, ppos
);
2064 set_max_threads(threads
);