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>
31 #include <linux/nsproxy.h>
32 #include <linux/capability.h>
33 #include <linux/cpu.h>
34 #include <linux/cgroup.h>
35 #include <linux/security.h>
36 #include <linux/hugetlb.h>
37 #include <linux/seccomp.h>
38 #include <linux/swap.h>
39 #include <linux/syscalls.h>
40 #include <linux/jiffies.h>
41 #include <linux/futex.h>
42 #include <linux/compat.h>
43 #include <linux/kthread.h>
44 #include <linux/task_io_accounting_ops.h>
45 #include <linux/rcupdate.h>
46 #include <linux/ptrace.h>
47 #include <linux/mount.h>
48 #include <linux/audit.h>
49 #include <linux/memcontrol.h>
50 #include <linux/ftrace.h>
51 #include <linux/proc_fs.h>
52 #include <linux/profile.h>
53 #include <linux/rmap.h>
54 #include <linux/ksm.h>
55 #include <linux/acct.h>
56 #include <linux/tsacct_kern.h>
57 #include <linux/cn_proc.h>
58 #include <linux/freezer.h>
59 #include <linux/delayacct.h>
60 #include <linux/taskstats_kern.h>
61 #include <linux/random.h>
62 #include <linux/tty.h>
63 #include <linux/blkdev.h>
64 #include <linux/fs_struct.h>
65 #include <linux/magic.h>
66 #include <linux/perf_event.h>
67 #include <linux/posix-timers.h>
68 #include <linux/user-return-notifier.h>
69 #include <linux/oom.h>
70 #include <linux/khugepaged.h>
71 #include <linux/signalfd.h>
72 #include <linux/uprobes.h>
73 #include <linux/aio.h>
75 #include <asm/pgtable.h>
76 #include <asm/pgalloc.h>
77 #include <asm/uaccess.h>
78 #include <asm/mmu_context.h>
79 #include <asm/cacheflush.h>
80 #include <asm/tlbflush.h>
82 #include <trace/events/sched.h>
84 #define CREATE_TRACE_POINTS
85 #include <trace/events/task.h>
88 * Protected counters by write_lock_irq(&tasklist_lock)
90 unsigned long total_forks
; /* Handle normal Linux uptimes. */
91 int nr_threads
; /* The idle threads do not count.. */
93 int max_threads
; /* tunable limit on nr_threads */
95 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
97 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
99 #ifdef CONFIG_PROVE_RCU
100 int lockdep_tasklist_lock_is_held(void)
102 return lockdep_is_held(&tasklist_lock
);
104 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
105 #endif /* #ifdef CONFIG_PROVE_RCU */
107 int nr_processes(void)
112 for_each_possible_cpu(cpu
)
113 total
+= per_cpu(process_counts
, cpu
);
118 void __weak
arch_release_task_struct(struct task_struct
*tsk
)
122 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
123 static struct kmem_cache
*task_struct_cachep
;
125 static inline struct task_struct
*alloc_task_struct_node(int node
)
127 return kmem_cache_alloc_node(task_struct_cachep
, GFP_KERNEL
, node
);
130 static inline void free_task_struct(struct task_struct
*tsk
)
132 kmem_cache_free(task_struct_cachep
, tsk
);
136 void __weak
arch_release_thread_info(struct thread_info
*ti
)
140 #ifndef CONFIG_ARCH_THREAD_INFO_ALLOCATOR
143 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
144 * kmemcache based allocator.
146 # if THREAD_SIZE >= PAGE_SIZE
147 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
150 struct page
*page
= alloc_pages_node(node
, THREADINFO_GFP_ACCOUNTED
,
153 return page
? page_address(page
) : NULL
;
156 static inline void free_thread_info(struct thread_info
*ti
)
158 free_memcg_kmem_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
161 static struct kmem_cache
*thread_info_cache
;
163 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
166 return kmem_cache_alloc_node(thread_info_cache
, THREADINFO_GFP
, node
);
169 static void free_thread_info(struct thread_info
*ti
)
171 kmem_cache_free(thread_info_cache
, ti
);
174 void thread_info_cache_init(void)
176 thread_info_cache
= kmem_cache_create("thread_info", THREAD_SIZE
,
177 THREAD_SIZE
, 0, NULL
);
178 BUG_ON(thread_info_cache
== NULL
);
183 /* SLAB cache for signal_struct structures (tsk->signal) */
184 static struct kmem_cache
*signal_cachep
;
186 /* SLAB cache for sighand_struct structures (tsk->sighand) */
187 struct kmem_cache
*sighand_cachep
;
189 /* SLAB cache for files_struct structures (tsk->files) */
190 struct kmem_cache
*files_cachep
;
192 /* SLAB cache for fs_struct structures (tsk->fs) */
193 struct kmem_cache
*fs_cachep
;
195 /* SLAB cache for vm_area_struct structures */
196 struct kmem_cache
*vm_area_cachep
;
198 /* SLAB cache for mm_struct structures (tsk->mm) */
199 static struct kmem_cache
*mm_cachep
;
201 static void account_kernel_stack(struct thread_info
*ti
, int account
)
203 struct zone
*zone
= page_zone(virt_to_page(ti
));
205 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
208 void free_task(struct task_struct
*tsk
)
210 account_kernel_stack(tsk
->stack
, -1);
211 arch_release_thread_info(tsk
->stack
);
212 free_thread_info(tsk
->stack
);
213 rt_mutex_debug_task_free(tsk
);
214 ftrace_graph_exit_task(tsk
);
215 put_seccomp_filter(tsk
);
216 arch_release_task_struct(tsk
);
217 free_task_struct(tsk
);
219 EXPORT_SYMBOL(free_task
);
221 static inline void free_signal_struct(struct signal_struct
*sig
)
223 taskstats_tgid_free(sig
);
224 sched_autogroup_exit(sig
);
225 kmem_cache_free(signal_cachep
, sig
);
228 static inline void put_signal_struct(struct signal_struct
*sig
)
230 if (atomic_dec_and_test(&sig
->sigcnt
))
231 free_signal_struct(sig
);
234 void __put_task_struct(struct task_struct
*tsk
)
236 WARN_ON(!tsk
->exit_state
);
237 WARN_ON(atomic_read(&tsk
->usage
));
238 WARN_ON(tsk
== current
);
241 security_task_free(tsk
);
243 delayacct_tsk_free(tsk
);
244 put_signal_struct(tsk
->signal
);
246 if (!profile_handoff_task(tsk
))
249 EXPORT_SYMBOL_GPL(__put_task_struct
);
251 void __init __weak
arch_task_cache_init(void) { }
253 void __init
fork_init(unsigned long mempages
)
255 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
256 #ifndef ARCH_MIN_TASKALIGN
257 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
259 /* create a slab on which task_structs can be allocated */
261 kmem_cache_create("task_struct", sizeof(struct task_struct
),
262 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
265 /* do the arch specific task caches init */
266 arch_task_cache_init();
269 * The default maximum number of threads is set to a safe
270 * value: the thread structures can take up at most half
273 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
276 * we need to allow at least 20 threads to boot a system
278 if (max_threads
< 20)
281 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
282 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
283 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
284 init_task
.signal
->rlim
[RLIMIT_NPROC
];
287 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
288 struct task_struct
*src
)
294 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
296 struct task_struct
*tsk
;
297 struct thread_info
*ti
;
298 unsigned long *stackend
;
299 int node
= tsk_fork_get_node(orig
);
302 tsk
= alloc_task_struct_node(node
);
306 ti
= alloc_thread_info_node(tsk
, node
);
310 err
= arch_dup_task_struct(tsk
, orig
);
316 setup_thread_stack(tsk
, orig
);
317 clear_user_return_notifier(tsk
);
318 clear_tsk_need_resched(tsk
);
319 stackend
= end_of_stack(tsk
);
320 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
322 #ifdef CONFIG_CC_STACKPROTECTOR
323 tsk
->stack_canary
= get_random_int();
327 * One for us, one for whoever does the "release_task()" (usually
330 atomic_set(&tsk
->usage
, 2);
331 #ifdef CONFIG_BLK_DEV_IO_TRACE
334 tsk
->splice_pipe
= NULL
;
335 tsk
->task_frag
.page
= NULL
;
337 account_kernel_stack(ti
, 1);
342 free_thread_info(ti
);
344 free_task_struct(tsk
);
349 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
351 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
352 struct rb_node
**rb_link
, *rb_parent
;
354 unsigned long charge
;
356 uprobe_start_dup_mmap();
357 down_write(&oldmm
->mmap_sem
);
358 flush_cache_dup_mm(oldmm
);
359 uprobe_dup_mmap(oldmm
, mm
);
361 * Not linked in yet - no deadlock potential:
363 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
367 mm
->mmap_cache
= NULL
;
369 cpumask_clear(mm_cpumask(mm
));
371 rb_link
= &mm
->mm_rb
.rb_node
;
374 retval
= ksm_fork(mm
, oldmm
);
377 retval
= khugepaged_fork(mm
, oldmm
);
382 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
385 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
386 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
391 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
392 unsigned long len
= vma_pages(mpnt
);
394 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
398 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
402 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
403 retval
= vma_dup_policy(mpnt
, tmp
);
405 goto fail_nomem_policy
;
407 if (anon_vma_fork(tmp
, mpnt
))
408 goto fail_nomem_anon_vma_fork
;
409 tmp
->vm_flags
&= ~VM_LOCKED
;
410 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
413 struct inode
*inode
= file_inode(file
);
414 struct address_space
*mapping
= file
->f_mapping
;
417 if (tmp
->vm_flags
& VM_DENYWRITE
)
418 atomic_dec(&inode
->i_writecount
);
419 mutex_lock(&mapping
->i_mmap_mutex
);
420 if (tmp
->vm_flags
& VM_SHARED
)
421 mapping
->i_mmap_writable
++;
422 flush_dcache_mmap_lock(mapping
);
423 /* insert tmp into the share list, just after mpnt */
424 if (unlikely(tmp
->vm_flags
& VM_NONLINEAR
))
425 vma_nonlinear_insert(tmp
,
426 &mapping
->i_mmap_nonlinear
);
428 vma_interval_tree_insert_after(tmp
, mpnt
,
430 flush_dcache_mmap_unlock(mapping
);
431 mutex_unlock(&mapping
->i_mmap_mutex
);
435 * Clear hugetlb-related page reserves for children. This only
436 * affects MAP_PRIVATE mappings. Faults generated by the child
437 * are not guaranteed to succeed, even if read-only
439 if (is_vm_hugetlb_page(tmp
))
440 reset_vma_resv_huge_pages(tmp
);
443 * Link in the new vma and copy the page table entries.
446 pprev
= &tmp
->vm_next
;
450 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
451 rb_link
= &tmp
->vm_rb
.rb_right
;
452 rb_parent
= &tmp
->vm_rb
;
455 retval
= copy_page_range(mm
, oldmm
, mpnt
);
457 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
458 tmp
->vm_ops
->open(tmp
);
463 /* a new mm has just been created */
464 arch_dup_mmap(oldmm
, mm
);
467 up_write(&mm
->mmap_sem
);
469 up_write(&oldmm
->mmap_sem
);
470 uprobe_end_dup_mmap();
472 fail_nomem_anon_vma_fork
:
473 mpol_put(vma_policy(tmp
));
475 kmem_cache_free(vm_area_cachep
, tmp
);
478 vm_unacct_memory(charge
);
482 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
484 mm
->pgd
= pgd_alloc(mm
);
485 if (unlikely(!mm
->pgd
))
490 static inline void mm_free_pgd(struct mm_struct
*mm
)
492 pgd_free(mm
, mm
->pgd
);
495 #define dup_mmap(mm, oldmm) (0)
496 #define mm_alloc_pgd(mm) (0)
497 #define mm_free_pgd(mm)
498 #endif /* CONFIG_MMU */
500 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
502 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
503 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
505 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
507 static int __init
coredump_filter_setup(char *s
)
509 default_dump_filter
=
510 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
511 MMF_DUMP_FILTER_MASK
;
515 __setup("coredump_filter=", coredump_filter_setup
);
517 #include <linux/init_task.h>
519 static void mm_init_aio(struct mm_struct
*mm
)
522 spin_lock_init(&mm
->ioctx_lock
);
523 mm
->ioctx_table
= NULL
;
527 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
)
529 atomic_set(&mm
->mm_users
, 1);
530 atomic_set(&mm
->mm_count
, 1);
531 init_rwsem(&mm
->mmap_sem
);
532 INIT_LIST_HEAD(&mm
->mmlist
);
533 mm
->flags
= (current
->mm
) ?
534 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
535 mm
->core_state
= NULL
;
536 atomic_long_set(&mm
->nr_ptes
, 0);
537 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
538 spin_lock_init(&mm
->page_table_lock
);
540 mm_init_owner(mm
, p
);
541 clear_tlb_flush_pending(mm
);
543 if (likely(!mm_alloc_pgd(mm
))) {
545 mmu_notifier_mm_init(mm
);
553 static void check_mm(struct mm_struct
*mm
)
557 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
558 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
561 printk(KERN_ALERT
"BUG: Bad rss-counter state "
562 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
565 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
566 VM_BUG_ON(mm
->pmd_huge_pte
);
571 * Allocate and initialize an mm_struct.
573 struct mm_struct
*mm_alloc(void)
575 struct mm_struct
*mm
;
581 memset(mm
, 0, sizeof(*mm
));
583 return mm_init(mm
, current
);
587 * Called when the last reference to the mm
588 * is dropped: either by a lazy thread or by
589 * mmput. Free the page directory and the mm.
591 void __mmdrop(struct mm_struct
*mm
)
593 BUG_ON(mm
== &init_mm
);
596 mmu_notifier_mm_destroy(mm
);
600 EXPORT_SYMBOL_GPL(__mmdrop
);
603 * Decrement the use count and release all resources for an mm.
605 void mmput(struct mm_struct
*mm
)
609 if (atomic_dec_and_test(&mm
->mm_users
)) {
610 uprobe_clear_state(mm
);
613 khugepaged_exit(mm
); /* must run before exit_mmap */
615 set_mm_exe_file(mm
, NULL
);
616 if (!list_empty(&mm
->mmlist
)) {
617 spin_lock(&mmlist_lock
);
618 list_del(&mm
->mmlist
);
619 spin_unlock(&mmlist_lock
);
622 module_put(mm
->binfmt
->module
);
626 EXPORT_SYMBOL_GPL(mmput
);
628 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
631 get_file(new_exe_file
);
634 mm
->exe_file
= new_exe_file
;
637 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
639 struct file
*exe_file
;
641 /* We need mmap_sem to protect against races with removal of exe_file */
642 down_read(&mm
->mmap_sem
);
643 exe_file
= mm
->exe_file
;
646 up_read(&mm
->mmap_sem
);
650 static void dup_mm_exe_file(struct mm_struct
*oldmm
, struct mm_struct
*newmm
)
652 /* It's safe to write the exe_file pointer without exe_file_lock because
653 * this is called during fork when the task is not yet in /proc */
654 newmm
->exe_file
= get_mm_exe_file(oldmm
);
658 * get_task_mm - acquire a reference to the task's mm
660 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
661 * this kernel workthread has transiently adopted a user mm with use_mm,
662 * to do its AIO) is not set and if so returns a reference to it, after
663 * bumping up the use count. User must release the mm via mmput()
664 * after use. Typically used by /proc and ptrace.
666 struct mm_struct
*get_task_mm(struct task_struct
*task
)
668 struct mm_struct
*mm
;
673 if (task
->flags
& PF_KTHREAD
)
676 atomic_inc(&mm
->mm_users
);
681 EXPORT_SYMBOL_GPL(get_task_mm
);
683 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
685 struct mm_struct
*mm
;
688 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
692 mm
= get_task_mm(task
);
693 if (mm
&& mm
!= current
->mm
&&
694 !ptrace_may_access(task
, mode
)) {
696 mm
= ERR_PTR(-EACCES
);
698 mutex_unlock(&task
->signal
->cred_guard_mutex
);
703 static void complete_vfork_done(struct task_struct
*tsk
)
705 struct completion
*vfork
;
708 vfork
= tsk
->vfork_done
;
710 tsk
->vfork_done
= NULL
;
716 static int wait_for_vfork_done(struct task_struct
*child
,
717 struct completion
*vfork
)
721 freezer_do_not_count();
722 killed
= wait_for_completion_killable(vfork
);
727 child
->vfork_done
= NULL
;
731 put_task_struct(child
);
735 /* Please note the differences between mmput and mm_release.
736 * mmput is called whenever we stop holding onto a mm_struct,
737 * error success whatever.
739 * mm_release is called after a mm_struct has been removed
740 * from the current process.
742 * This difference is important for error handling, when we
743 * only half set up a mm_struct for a new process and need to restore
744 * the old one. Because we mmput the new mm_struct before
745 * restoring the old one. . .
746 * Eric Biederman 10 January 1998
748 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
750 /* Get rid of any futexes when releasing the mm */
752 if (unlikely(tsk
->robust_list
)) {
753 exit_robust_list(tsk
);
754 tsk
->robust_list
= NULL
;
757 if (unlikely(tsk
->compat_robust_list
)) {
758 compat_exit_robust_list(tsk
);
759 tsk
->compat_robust_list
= NULL
;
762 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
763 exit_pi_state_list(tsk
);
766 uprobe_free_utask(tsk
);
768 /* Get rid of any cached register state */
769 deactivate_mm(tsk
, mm
);
772 * If we're exiting normally, clear a user-space tid field if
773 * requested. We leave this alone when dying by signal, to leave
774 * the value intact in a core dump, and to save the unnecessary
775 * trouble, say, a killed vfork parent shouldn't touch this mm.
776 * Userland only wants this done for a sys_exit.
778 if (tsk
->clear_child_tid
) {
779 if (!(tsk
->flags
& PF_SIGNALED
) &&
780 atomic_read(&mm
->mm_users
) > 1) {
782 * We don't check the error code - if userspace has
783 * not set up a proper pointer then tough luck.
785 put_user(0, tsk
->clear_child_tid
);
786 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
789 tsk
->clear_child_tid
= NULL
;
793 * All done, finally we can wake up parent and return this mm to him.
794 * Also kthread_stop() uses this completion for synchronization.
797 complete_vfork_done(tsk
);
801 * Allocate a new mm structure and copy contents from the
802 * mm structure of the passed in task structure.
804 static struct mm_struct
*dup_mm(struct task_struct
*tsk
)
806 struct mm_struct
*mm
, *oldmm
= current
->mm
;
813 memcpy(mm
, oldmm
, sizeof(*mm
));
816 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
817 mm
->pmd_huge_pte
= NULL
;
819 if (!mm_init(mm
, tsk
))
822 if (init_new_context(tsk
, mm
))
825 dup_mm_exe_file(oldmm
, mm
);
827 err
= dup_mmap(mm
, oldmm
);
831 mm
->hiwater_rss
= get_mm_rss(mm
);
832 mm
->hiwater_vm
= mm
->total_vm
;
834 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
840 /* don't put binfmt in mmput, we haven't got module yet */
849 * If init_new_context() failed, we cannot use mmput() to free the mm
850 * because it calls destroy_context()
857 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
859 struct mm_struct
*mm
, *oldmm
;
862 tsk
->min_flt
= tsk
->maj_flt
= 0;
863 tsk
->nvcsw
= tsk
->nivcsw
= 0;
864 #ifdef CONFIG_DETECT_HUNG_TASK
865 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
869 tsk
->active_mm
= NULL
;
872 * Are we cloning a kernel thread?
874 * We need to steal a active VM for that..
880 if (clone_flags
& CLONE_VM
) {
881 atomic_inc(&oldmm
->mm_users
);
900 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
902 struct fs_struct
*fs
= current
->fs
;
903 if (clone_flags
& CLONE_FS
) {
904 /* tsk->fs is already what we want */
905 spin_lock(&fs
->lock
);
907 spin_unlock(&fs
->lock
);
911 spin_unlock(&fs
->lock
);
914 tsk
->fs
= copy_fs_struct(fs
);
920 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
922 struct files_struct
*oldf
, *newf
;
926 * A background process may not have any files ...
928 oldf
= current
->files
;
932 if (clone_flags
& CLONE_FILES
) {
933 atomic_inc(&oldf
->count
);
937 newf
= dup_fd(oldf
, &error
);
947 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
950 struct io_context
*ioc
= current
->io_context
;
951 struct io_context
*new_ioc
;
956 * Share io context with parent, if CLONE_IO is set
958 if (clone_flags
& CLONE_IO
) {
960 tsk
->io_context
= ioc
;
961 } else if (ioprio_valid(ioc
->ioprio
)) {
962 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
963 if (unlikely(!new_ioc
))
966 new_ioc
->ioprio
= ioc
->ioprio
;
967 put_io_context(new_ioc
);
973 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
975 struct sighand_struct
*sig
;
977 if (clone_flags
& CLONE_SIGHAND
) {
978 atomic_inc(¤t
->sighand
->count
);
981 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
982 rcu_assign_pointer(tsk
->sighand
, sig
);
985 atomic_set(&sig
->count
, 1);
986 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
990 void __cleanup_sighand(struct sighand_struct
*sighand
)
992 if (atomic_dec_and_test(&sighand
->count
)) {
993 signalfd_cleanup(sighand
);
994 kmem_cache_free(sighand_cachep
, sighand
);
1000 * Initialize POSIX timer handling for a thread group.
1002 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1004 unsigned long cpu_limit
;
1006 /* Thread group counters. */
1007 thread_group_cputime_init(sig
);
1009 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1010 if (cpu_limit
!= RLIM_INFINITY
) {
1011 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1012 sig
->cputimer
.running
= 1;
1015 /* The timer lists. */
1016 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1017 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1018 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1021 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1023 struct signal_struct
*sig
;
1025 if (clone_flags
& CLONE_THREAD
)
1028 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1033 sig
->nr_threads
= 1;
1034 atomic_set(&sig
->live
, 1);
1035 atomic_set(&sig
->sigcnt
, 1);
1037 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1038 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1039 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1041 init_waitqueue_head(&sig
->wait_chldexit
);
1042 sig
->curr_target
= tsk
;
1043 init_sigpending(&sig
->shared_pending
);
1044 INIT_LIST_HEAD(&sig
->posix_timers
);
1046 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1047 sig
->real_timer
.function
= it_real_fn
;
1049 task_lock(current
->group_leader
);
1050 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1051 task_unlock(current
->group_leader
);
1053 posix_cpu_timers_init_group(sig
);
1055 tty_audit_fork(sig
);
1056 sched_autogroup_fork(sig
);
1058 #ifdef CONFIG_CGROUPS
1059 init_rwsem(&sig
->group_rwsem
);
1062 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1063 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1065 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1066 current
->signal
->is_child_subreaper
;
1068 mutex_init(&sig
->cred_guard_mutex
);
1073 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
1075 unsigned long new_flags
= p
->flags
;
1077 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
1078 new_flags
|= PF_FORKNOEXEC
;
1079 p
->flags
= new_flags
;
1082 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1084 current
->clear_child_tid
= tidptr
;
1086 return task_pid_vnr(current
);
1089 static void rt_mutex_init_task(struct task_struct
*p
)
1091 raw_spin_lock_init(&p
->pi_lock
);
1092 #ifdef CONFIG_RT_MUTEXES
1093 p
->pi_waiters
= RB_ROOT
;
1094 p
->pi_waiters_leftmost
= NULL
;
1095 p
->pi_blocked_on
= NULL
;
1096 p
->pi_top_task
= NULL
;
1100 #ifdef CONFIG_MM_OWNER
1101 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1105 #endif /* CONFIG_MM_OWNER */
1108 * Initialize POSIX timer handling for a single task.
1110 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1112 tsk
->cputime_expires
.prof_exp
= 0;
1113 tsk
->cputime_expires
.virt_exp
= 0;
1114 tsk
->cputime_expires
.sched_exp
= 0;
1115 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1116 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1117 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1121 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1123 task
->pids
[type
].pid
= pid
;
1127 * This creates a new process as a copy of the old one,
1128 * but does not actually start it yet.
1130 * It copies the registers, and all the appropriate
1131 * parts of the process environment (as per the clone
1132 * flags). The actual kick-off is left to the caller.
1134 static struct task_struct
*copy_process(unsigned long clone_flags
,
1135 unsigned long stack_start
,
1136 unsigned long stack_size
,
1137 int __user
*child_tidptr
,
1142 struct task_struct
*p
;
1144 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1145 return ERR_PTR(-EINVAL
);
1147 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1148 return ERR_PTR(-EINVAL
);
1151 * Thread groups must share signals as well, and detached threads
1152 * can only be started up within the thread group.
1154 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1155 return ERR_PTR(-EINVAL
);
1158 * Shared signal handlers imply shared VM. By way of the above,
1159 * thread groups also imply shared VM. Blocking this case allows
1160 * for various simplifications in other code.
1162 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1163 return ERR_PTR(-EINVAL
);
1166 * Siblings of global init remain as zombies on exit since they are
1167 * not reaped by their parent (swapper). To solve this and to avoid
1168 * multi-rooted process trees, prevent global and container-inits
1169 * from creating siblings.
1171 if ((clone_flags
& CLONE_PARENT
) &&
1172 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1173 return ERR_PTR(-EINVAL
);
1176 * If the new process will be in a different pid or user namespace
1177 * do not allow it to share a thread group or signal handlers or
1178 * parent with the forking task.
1180 if (clone_flags
& CLONE_SIGHAND
) {
1181 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1182 (task_active_pid_ns(current
) !=
1183 current
->nsproxy
->pid_ns_for_children
))
1184 return ERR_PTR(-EINVAL
);
1187 retval
= security_task_create(clone_flags
);
1192 p
= dup_task_struct(current
);
1196 ftrace_graph_init_task(p
);
1197 get_seccomp_filter(p
);
1199 rt_mutex_init_task(p
);
1201 #ifdef CONFIG_PROVE_LOCKING
1202 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1203 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1206 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1207 task_rlimit(p
, RLIMIT_NPROC
)) {
1208 if (p
->real_cred
->user
!= INIT_USER
&&
1209 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1212 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1214 retval
= copy_creds(p
, clone_flags
);
1219 * If multiple threads are within copy_process(), then this check
1220 * triggers too late. This doesn't hurt, the check is only there
1221 * to stop root fork bombs.
1224 if (nr_threads
>= max_threads
)
1225 goto bad_fork_cleanup_count
;
1227 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1228 goto bad_fork_cleanup_count
;
1230 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1231 copy_flags(clone_flags
, p
);
1232 INIT_LIST_HEAD(&p
->children
);
1233 INIT_LIST_HEAD(&p
->sibling
);
1234 rcu_copy_process(p
);
1235 p
->vfork_done
= NULL
;
1236 spin_lock_init(&p
->alloc_lock
);
1238 init_sigpending(&p
->pending
);
1240 p
->utime
= p
->stime
= p
->gtime
= 0;
1241 p
->utimescaled
= p
->stimescaled
= 0;
1242 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
1243 p
->prev_cputime
.utime
= p
->prev_cputime
.stime
= 0;
1245 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1246 seqlock_init(&p
->vtime_seqlock
);
1248 p
->vtime_snap_whence
= VTIME_SLEEPING
;
1251 #if defined(SPLIT_RSS_COUNTING)
1252 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1255 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1257 task_io_accounting_init(&p
->ioac
);
1258 acct_clear_integrals(p
);
1260 posix_cpu_timers_init(p
);
1262 do_posix_clock_monotonic_gettime(&p
->start_time
);
1263 p
->real_start_time
= p
->start_time
;
1264 monotonic_to_bootbased(&p
->real_start_time
);
1265 p
->io_context
= NULL
;
1266 p
->audit_context
= NULL
;
1267 if (clone_flags
& CLONE_THREAD
)
1268 threadgroup_change_begin(current
);
1271 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1272 if (IS_ERR(p
->mempolicy
)) {
1273 retval
= PTR_ERR(p
->mempolicy
);
1274 p
->mempolicy
= NULL
;
1275 goto bad_fork_cleanup_cgroup
;
1277 mpol_fix_fork_child_flag(p
);
1279 #ifdef CONFIG_CPUSETS
1280 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1281 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1282 seqcount_init(&p
->mems_allowed_seq
);
1284 #ifdef CONFIG_TRACE_IRQFLAGS
1286 p
->hardirqs_enabled
= 0;
1287 p
->hardirq_enable_ip
= 0;
1288 p
->hardirq_enable_event
= 0;
1289 p
->hardirq_disable_ip
= _THIS_IP_
;
1290 p
->hardirq_disable_event
= 0;
1291 p
->softirqs_enabled
= 1;
1292 p
->softirq_enable_ip
= _THIS_IP_
;
1293 p
->softirq_enable_event
= 0;
1294 p
->softirq_disable_ip
= 0;
1295 p
->softirq_disable_event
= 0;
1296 p
->hardirq_context
= 0;
1297 p
->softirq_context
= 0;
1299 #ifdef CONFIG_LOCKDEP
1300 p
->lockdep_depth
= 0; /* no locks held yet */
1301 p
->curr_chain_key
= 0;
1302 p
->lockdep_recursion
= 0;
1305 #ifdef CONFIG_DEBUG_MUTEXES
1306 p
->blocked_on
= NULL
; /* not blocked yet */
1309 p
->memcg_batch
.do_batch
= 0;
1310 p
->memcg_batch
.memcg
= NULL
;
1312 #ifdef CONFIG_BCACHE
1313 p
->sequential_io
= 0;
1314 p
->sequential_io_avg
= 0;
1317 /* Perform scheduler related setup. Assign this task to a CPU. */
1318 retval
= sched_fork(clone_flags
, p
);
1320 goto bad_fork_cleanup_policy
;
1322 retval
= perf_event_init_task(p
);
1324 goto bad_fork_cleanup_policy
;
1325 retval
= audit_alloc(p
);
1327 goto bad_fork_cleanup_policy
;
1328 /* copy all the process information */
1329 retval
= copy_semundo(clone_flags
, p
);
1331 goto bad_fork_cleanup_audit
;
1332 retval
= copy_files(clone_flags
, p
);
1334 goto bad_fork_cleanup_semundo
;
1335 retval
= copy_fs(clone_flags
, p
);
1337 goto bad_fork_cleanup_files
;
1338 retval
= copy_sighand(clone_flags
, p
);
1340 goto bad_fork_cleanup_fs
;
1341 retval
= copy_signal(clone_flags
, p
);
1343 goto bad_fork_cleanup_sighand
;
1344 retval
= copy_mm(clone_flags
, p
);
1346 goto bad_fork_cleanup_signal
;
1347 retval
= copy_namespaces(clone_flags
, p
);
1349 goto bad_fork_cleanup_mm
;
1350 retval
= copy_io(clone_flags
, p
);
1352 goto bad_fork_cleanup_namespaces
;
1353 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
);
1355 goto bad_fork_cleanup_io
;
1357 if (pid
!= &init_struct_pid
) {
1359 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1361 goto bad_fork_cleanup_io
;
1364 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1366 * Clear TID on mm_release()?
1368 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1373 p
->robust_list
= NULL
;
1374 #ifdef CONFIG_COMPAT
1375 p
->compat_robust_list
= NULL
;
1377 INIT_LIST_HEAD(&p
->pi_state_list
);
1378 p
->pi_state_cache
= NULL
;
1381 * sigaltstack should be cleared when sharing the same VM
1383 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1384 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1387 * Syscall tracing and stepping should be turned off in the
1388 * child regardless of CLONE_PTRACE.
1390 user_disable_single_step(p
);
1391 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1392 #ifdef TIF_SYSCALL_EMU
1393 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1395 clear_all_latency_tracing(p
);
1397 /* ok, now we should be set up.. */
1398 p
->pid
= pid_nr(pid
);
1399 if (clone_flags
& CLONE_THREAD
) {
1400 p
->exit_signal
= -1;
1401 p
->group_leader
= current
->group_leader
;
1402 p
->tgid
= current
->tgid
;
1404 if (clone_flags
& CLONE_PARENT
)
1405 p
->exit_signal
= current
->group_leader
->exit_signal
;
1407 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1408 p
->group_leader
= p
;
1413 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1414 p
->dirty_paused_when
= 0;
1416 p
->pdeath_signal
= 0;
1417 INIT_LIST_HEAD(&p
->thread_group
);
1418 p
->task_works
= NULL
;
1421 * Make it visible to the rest of the system, but dont wake it up yet.
1422 * Need tasklist lock for parent etc handling!
1424 write_lock_irq(&tasklist_lock
);
1426 /* CLONE_PARENT re-uses the old parent */
1427 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1428 p
->real_parent
= current
->real_parent
;
1429 p
->parent_exec_id
= current
->parent_exec_id
;
1431 p
->real_parent
= current
;
1432 p
->parent_exec_id
= current
->self_exec_id
;
1435 spin_lock(¤t
->sighand
->siglock
);
1438 * Process group and session signals need to be delivered to just the
1439 * parent before the fork or both the parent and the child after the
1440 * fork. Restart if a signal comes in before we add the new process to
1441 * it's process group.
1442 * A fatal signal pending means that current will exit, so the new
1443 * thread can't slip out of an OOM kill (or normal SIGKILL).
1445 recalc_sigpending();
1446 if (signal_pending(current
)) {
1447 spin_unlock(¤t
->sighand
->siglock
);
1448 write_unlock_irq(&tasklist_lock
);
1449 retval
= -ERESTARTNOINTR
;
1450 goto bad_fork_free_pid
;
1453 if (likely(p
->pid
)) {
1454 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1456 init_task_pid(p
, PIDTYPE_PID
, pid
);
1457 if (thread_group_leader(p
)) {
1458 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1459 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1461 if (is_child_reaper(pid
)) {
1462 ns_of_pid(pid
)->child_reaper
= p
;
1463 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1466 p
->signal
->leader_pid
= pid
;
1467 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1468 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1469 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1470 attach_pid(p
, PIDTYPE_PGID
);
1471 attach_pid(p
, PIDTYPE_SID
);
1472 __this_cpu_inc(process_counts
);
1474 current
->signal
->nr_threads
++;
1475 atomic_inc(¤t
->signal
->live
);
1476 atomic_inc(¤t
->signal
->sigcnt
);
1477 list_add_tail_rcu(&p
->thread_group
,
1478 &p
->group_leader
->thread_group
);
1479 list_add_tail_rcu(&p
->thread_node
,
1480 &p
->signal
->thread_head
);
1482 attach_pid(p
, PIDTYPE_PID
);
1487 spin_unlock(¤t
->sighand
->siglock
);
1488 write_unlock_irq(&tasklist_lock
);
1489 proc_fork_connector(p
);
1490 cgroup_post_fork(p
);
1491 if (clone_flags
& CLONE_THREAD
)
1492 threadgroup_change_end(current
);
1495 trace_task_newtask(p
, clone_flags
);
1496 uprobe_copy_process(p
, clone_flags
);
1501 if (pid
!= &init_struct_pid
)
1503 bad_fork_cleanup_io
:
1506 bad_fork_cleanup_namespaces
:
1507 exit_task_namespaces(p
);
1508 bad_fork_cleanup_mm
:
1511 bad_fork_cleanup_signal
:
1512 if (!(clone_flags
& CLONE_THREAD
))
1513 free_signal_struct(p
->signal
);
1514 bad_fork_cleanup_sighand
:
1515 __cleanup_sighand(p
->sighand
);
1516 bad_fork_cleanup_fs
:
1517 exit_fs(p
); /* blocking */
1518 bad_fork_cleanup_files
:
1519 exit_files(p
); /* blocking */
1520 bad_fork_cleanup_semundo
:
1522 bad_fork_cleanup_audit
:
1524 bad_fork_cleanup_policy
:
1525 perf_event_free_task(p
);
1527 mpol_put(p
->mempolicy
);
1528 bad_fork_cleanup_cgroup
:
1530 if (clone_flags
& CLONE_THREAD
)
1531 threadgroup_change_end(current
);
1533 delayacct_tsk_free(p
);
1534 module_put(task_thread_info(p
)->exec_domain
->module
);
1535 bad_fork_cleanup_count
:
1536 atomic_dec(&p
->cred
->user
->processes
);
1541 return ERR_PTR(retval
);
1544 static inline void init_idle_pids(struct pid_link
*links
)
1548 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1549 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1550 links
[type
].pid
= &init_struct_pid
;
1554 struct task_struct
*fork_idle(int cpu
)
1556 struct task_struct
*task
;
1557 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0);
1558 if (!IS_ERR(task
)) {
1559 init_idle_pids(task
->pids
);
1560 init_idle(task
, cpu
);
1567 * Ok, this is the main fork-routine.
1569 * It copies the process, and if successful kick-starts
1570 * it and waits for it to finish using the VM if required.
1572 long do_fork(unsigned long clone_flags
,
1573 unsigned long stack_start
,
1574 unsigned long stack_size
,
1575 int __user
*parent_tidptr
,
1576 int __user
*child_tidptr
)
1578 struct task_struct
*p
;
1583 * Determine whether and which event to report to ptracer. When
1584 * called from kernel_thread or CLONE_UNTRACED is explicitly
1585 * requested, no event is reported; otherwise, report if the event
1586 * for the type of forking is enabled.
1588 if (!(clone_flags
& CLONE_UNTRACED
)) {
1589 if (clone_flags
& CLONE_VFORK
)
1590 trace
= PTRACE_EVENT_VFORK
;
1591 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1592 trace
= PTRACE_EVENT_CLONE
;
1594 trace
= PTRACE_EVENT_FORK
;
1596 if (likely(!ptrace_event_enabled(current
, trace
)))
1600 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1601 child_tidptr
, NULL
, trace
);
1603 * Do this prior waking up the new thread - the thread pointer
1604 * might get invalid after that point, if the thread exits quickly.
1607 struct completion vfork
;
1609 trace_sched_process_fork(current
, p
);
1611 nr
= task_pid_vnr(p
);
1613 if (clone_flags
& CLONE_PARENT_SETTID
)
1614 put_user(nr
, parent_tidptr
);
1616 if (clone_flags
& CLONE_VFORK
) {
1617 p
->vfork_done
= &vfork
;
1618 init_completion(&vfork
);
1622 wake_up_new_task(p
);
1624 /* forking complete and child started to run, tell ptracer */
1625 if (unlikely(trace
))
1626 ptrace_event(trace
, nr
);
1628 if (clone_flags
& CLONE_VFORK
) {
1629 if (!wait_for_vfork_done(p
, &vfork
))
1630 ptrace_event(PTRACE_EVENT_VFORK_DONE
, nr
);
1639 * Create a kernel thread.
1641 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
1643 return do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
1644 (unsigned long)arg
, NULL
, NULL
);
1647 #ifdef __ARCH_WANT_SYS_FORK
1648 SYSCALL_DEFINE0(fork
)
1651 return do_fork(SIGCHLD
, 0, 0, NULL
, NULL
);
1653 /* can not support in nommu mode */
1659 #ifdef __ARCH_WANT_SYS_VFORK
1660 SYSCALL_DEFINE0(vfork
)
1662 return do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
1667 #ifdef __ARCH_WANT_SYS_CLONE
1668 #ifdef CONFIG_CLONE_BACKWARDS
1669 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1670 int __user
*, parent_tidptr
,
1672 int __user
*, child_tidptr
)
1673 #elif defined(CONFIG_CLONE_BACKWARDS2)
1674 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
1675 int __user
*, parent_tidptr
,
1676 int __user
*, child_tidptr
,
1678 #elif defined(CONFIG_CLONE_BACKWARDS3)
1679 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1681 int __user
*, parent_tidptr
,
1682 int __user
*, child_tidptr
,
1685 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1686 int __user
*, parent_tidptr
,
1687 int __user
*, child_tidptr
,
1691 return do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
);
1695 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1696 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1699 static void sighand_ctor(void *data
)
1701 struct sighand_struct
*sighand
= data
;
1703 spin_lock_init(&sighand
->siglock
);
1704 init_waitqueue_head(&sighand
->signalfd_wqh
);
1707 void __init
proc_caches_init(void)
1709 sighand_cachep
= kmem_cache_create("sighand_cache",
1710 sizeof(struct sighand_struct
), 0,
1711 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1712 SLAB_NOTRACK
, sighand_ctor
);
1713 signal_cachep
= kmem_cache_create("signal_cache",
1714 sizeof(struct signal_struct
), 0,
1715 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1716 files_cachep
= kmem_cache_create("files_cache",
1717 sizeof(struct files_struct
), 0,
1718 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1719 fs_cachep
= kmem_cache_create("fs_cache",
1720 sizeof(struct fs_struct
), 0,
1721 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1723 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1724 * whole struct cpumask for the OFFSTACK case. We could change
1725 * this to *only* allocate as much of it as required by the
1726 * maximum number of CPU's we can ever have. The cpumask_allocation
1727 * is at the end of the structure, exactly for that reason.
1729 mm_cachep
= kmem_cache_create("mm_struct",
1730 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1731 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1732 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1734 nsproxy_cache_init();
1738 * Check constraints on flags passed to the unshare system call.
1740 static int check_unshare_flags(unsigned long unshare_flags
)
1742 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1743 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1744 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
1745 CLONE_NEWUSER
|CLONE_NEWPID
))
1748 * Not implemented, but pretend it works if there is nothing to
1749 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1750 * needs to unshare vm.
1752 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
1753 /* FIXME: get_task_mm() increments ->mm_users */
1754 if (atomic_read(¤t
->mm
->mm_users
) > 1)
1762 * Unshare the filesystem structure if it is being shared
1764 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1766 struct fs_struct
*fs
= current
->fs
;
1768 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1771 /* don't need lock here; in the worst case we'll do useless copy */
1775 *new_fsp
= copy_fs_struct(fs
);
1783 * Unshare file descriptor table if it is being shared
1785 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1787 struct files_struct
*fd
= current
->files
;
1790 if ((unshare_flags
& CLONE_FILES
) &&
1791 (fd
&& atomic_read(&fd
->count
) > 1)) {
1792 *new_fdp
= dup_fd(fd
, &error
);
1801 * unshare allows a process to 'unshare' part of the process
1802 * context which was originally shared using clone. copy_*
1803 * functions used by do_fork() cannot be used here directly
1804 * because they modify an inactive task_struct that is being
1805 * constructed. Here we are modifying the current, active,
1808 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1810 struct fs_struct
*fs
, *new_fs
= NULL
;
1811 struct files_struct
*fd
, *new_fd
= NULL
;
1812 struct cred
*new_cred
= NULL
;
1813 struct nsproxy
*new_nsproxy
= NULL
;
1818 * If unsharing a user namespace must also unshare the thread.
1820 if (unshare_flags
& CLONE_NEWUSER
)
1821 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
1823 * If unsharing a thread from a thread group, must also unshare vm.
1825 if (unshare_flags
& CLONE_THREAD
)
1826 unshare_flags
|= CLONE_VM
;
1828 * If unsharing vm, must also unshare signal handlers.
1830 if (unshare_flags
& CLONE_VM
)
1831 unshare_flags
|= CLONE_SIGHAND
;
1833 * If unsharing namespace, must also unshare filesystem information.
1835 if (unshare_flags
& CLONE_NEWNS
)
1836 unshare_flags
|= CLONE_FS
;
1838 err
= check_unshare_flags(unshare_flags
);
1840 goto bad_unshare_out
;
1842 * CLONE_NEWIPC must also detach from the undolist: after switching
1843 * to a new ipc namespace, the semaphore arrays from the old
1844 * namespace are unreachable.
1846 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1848 err
= unshare_fs(unshare_flags
, &new_fs
);
1850 goto bad_unshare_out
;
1851 err
= unshare_fd(unshare_flags
, &new_fd
);
1853 goto bad_unshare_cleanup_fs
;
1854 err
= unshare_userns(unshare_flags
, &new_cred
);
1856 goto bad_unshare_cleanup_fd
;
1857 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1860 goto bad_unshare_cleanup_cred
;
1862 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
1865 * CLONE_SYSVSEM is equivalent to sys_exit().
1871 switch_task_namespaces(current
, new_nsproxy
);
1877 spin_lock(&fs
->lock
);
1878 current
->fs
= new_fs
;
1883 spin_unlock(&fs
->lock
);
1887 fd
= current
->files
;
1888 current
->files
= new_fd
;
1892 task_unlock(current
);
1895 /* Install the new user namespace */
1896 commit_creds(new_cred
);
1901 bad_unshare_cleanup_cred
:
1904 bad_unshare_cleanup_fd
:
1906 put_files_struct(new_fd
);
1908 bad_unshare_cleanup_fs
:
1910 free_fs_struct(new_fs
);
1917 * Helper to unshare the files of the current task.
1918 * We don't want to expose copy_files internals to
1919 * the exec layer of the kernel.
1922 int unshare_files(struct files_struct
**displaced
)
1924 struct task_struct
*task
= current
;
1925 struct files_struct
*copy
= NULL
;
1928 error
= unshare_fd(CLONE_FILES
, ©
);
1929 if (error
|| !copy
) {
1933 *displaced
= task
->files
;