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
);
240 security_task_free(tsk
);
242 delayacct_tsk_free(tsk
);
243 put_signal_struct(tsk
->signal
);
245 if (!profile_handoff_task(tsk
))
248 EXPORT_SYMBOL_GPL(__put_task_struct
);
250 void __init __weak
arch_task_cache_init(void) { }
252 void __init
fork_init(unsigned long mempages
)
254 #ifndef CONFIG_ARCH_TASK_STRUCT_ALLOCATOR
255 #ifndef ARCH_MIN_TASKALIGN
256 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
258 /* create a slab on which task_structs can be allocated */
260 kmem_cache_create("task_struct", sizeof(struct task_struct
),
261 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
264 /* do the arch specific task caches init */
265 arch_task_cache_init();
268 * The default maximum number of threads is set to a safe
269 * value: the thread structures can take up at most half
272 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
275 * we need to allow at least 20 threads to boot a system
277 if (max_threads
< 20)
280 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
281 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
282 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
283 init_task
.signal
->rlim
[RLIMIT_NPROC
];
286 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
287 struct task_struct
*src
)
293 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
295 struct task_struct
*tsk
;
296 struct thread_info
*ti
;
297 unsigned long *stackend
;
298 int node
= tsk_fork_get_node(orig
);
301 tsk
= alloc_task_struct_node(node
);
305 ti
= alloc_thread_info_node(tsk
, node
);
309 err
= arch_dup_task_struct(tsk
, orig
);
315 setup_thread_stack(tsk
, orig
);
316 clear_user_return_notifier(tsk
);
317 clear_tsk_need_resched(tsk
);
318 stackend
= end_of_stack(tsk
);
319 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
321 #ifdef CONFIG_CC_STACKPROTECTOR
322 tsk
->stack_canary
= get_random_int();
326 * One for us, one for whoever does the "release_task()" (usually
329 atomic_set(&tsk
->usage
, 2);
330 #ifdef CONFIG_BLK_DEV_IO_TRACE
333 tsk
->splice_pipe
= NULL
;
334 tsk
->task_frag
.page
= NULL
;
336 account_kernel_stack(ti
, 1);
341 free_thread_info(ti
);
343 free_task_struct(tsk
);
348 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
350 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
351 struct rb_node
**rb_link
, *rb_parent
;
353 unsigned long charge
;
355 uprobe_start_dup_mmap();
356 down_write(&oldmm
->mmap_sem
);
357 flush_cache_dup_mm(oldmm
);
358 uprobe_dup_mmap(oldmm
, mm
);
360 * Not linked in yet - no deadlock potential:
362 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
366 mm
->mmap_cache
= NULL
;
368 cpumask_clear(mm_cpumask(mm
));
370 rb_link
= &mm
->mm_rb
.rb_node
;
373 retval
= ksm_fork(mm
, oldmm
);
376 retval
= khugepaged_fork(mm
, oldmm
);
381 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
384 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
385 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
390 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
391 unsigned long len
= vma_pages(mpnt
);
393 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
397 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
401 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
402 retval
= vma_dup_policy(mpnt
, tmp
);
404 goto fail_nomem_policy
;
406 if (anon_vma_fork(tmp
, mpnt
))
407 goto fail_nomem_anon_vma_fork
;
408 tmp
->vm_flags
&= ~VM_LOCKED
;
409 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
412 struct inode
*inode
= file_inode(file
);
413 struct address_space
*mapping
= file
->f_mapping
;
416 if (tmp
->vm_flags
& VM_DENYWRITE
)
417 atomic_dec(&inode
->i_writecount
);
418 mutex_lock(&mapping
->i_mmap_mutex
);
419 if (tmp
->vm_flags
& VM_SHARED
)
420 mapping
->i_mmap_writable
++;
421 flush_dcache_mmap_lock(mapping
);
422 /* insert tmp into the share list, just after mpnt */
423 if (unlikely(tmp
->vm_flags
& VM_NONLINEAR
))
424 vma_nonlinear_insert(tmp
,
425 &mapping
->i_mmap_nonlinear
);
427 vma_interval_tree_insert_after(tmp
, mpnt
,
429 flush_dcache_mmap_unlock(mapping
);
430 mutex_unlock(&mapping
->i_mmap_mutex
);
434 * Clear hugetlb-related page reserves for children. This only
435 * affects MAP_PRIVATE mappings. Faults generated by the child
436 * are not guaranteed to succeed, even if read-only
438 if (is_vm_hugetlb_page(tmp
))
439 reset_vma_resv_huge_pages(tmp
);
442 * Link in the new vma and copy the page table entries.
445 pprev
= &tmp
->vm_next
;
449 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
450 rb_link
= &tmp
->vm_rb
.rb_right
;
451 rb_parent
= &tmp
->vm_rb
;
454 retval
= copy_page_range(mm
, oldmm
, mpnt
);
456 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
457 tmp
->vm_ops
->open(tmp
);
462 /* a new mm has just been created */
463 arch_dup_mmap(oldmm
, mm
);
466 up_write(&mm
->mmap_sem
);
468 up_write(&oldmm
->mmap_sem
);
469 uprobe_end_dup_mmap();
471 fail_nomem_anon_vma_fork
:
472 mpol_put(vma_policy(tmp
));
474 kmem_cache_free(vm_area_cachep
, tmp
);
477 vm_unacct_memory(charge
);
481 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
483 mm
->pgd
= pgd_alloc(mm
);
484 if (unlikely(!mm
->pgd
))
489 static inline void mm_free_pgd(struct mm_struct
*mm
)
491 pgd_free(mm
, mm
->pgd
);
494 #define dup_mmap(mm, oldmm) (0)
495 #define mm_alloc_pgd(mm) (0)
496 #define mm_free_pgd(mm)
497 #endif /* CONFIG_MMU */
499 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
501 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
502 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
504 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
506 static int __init
coredump_filter_setup(char *s
)
508 default_dump_filter
=
509 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
510 MMF_DUMP_FILTER_MASK
;
514 __setup("coredump_filter=", coredump_filter_setup
);
516 #include <linux/init_task.h>
518 static void mm_init_aio(struct mm_struct
*mm
)
521 spin_lock_init(&mm
->ioctx_lock
);
522 mm
->ioctx_table
= NULL
;
526 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
)
528 atomic_set(&mm
->mm_users
, 1);
529 atomic_set(&mm
->mm_count
, 1);
530 init_rwsem(&mm
->mmap_sem
);
531 INIT_LIST_HEAD(&mm
->mmlist
);
532 mm
->flags
= (current
->mm
) ?
533 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
534 mm
->core_state
= NULL
;
536 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
537 spin_lock_init(&mm
->page_table_lock
);
539 mm_init_owner(mm
, p
);
540 clear_tlb_flush_pending(mm
);
542 if (likely(!mm_alloc_pgd(mm
))) {
544 mmu_notifier_mm_init(mm
);
552 static void check_mm(struct mm_struct
*mm
)
556 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
557 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
560 printk(KERN_ALERT
"BUG: Bad rss-counter state "
561 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
564 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
565 VM_BUG_ON(mm
->pmd_huge_pte
);
570 * Allocate and initialize an mm_struct.
572 struct mm_struct
*mm_alloc(void)
574 struct mm_struct
*mm
;
580 memset(mm
, 0, sizeof(*mm
));
582 return mm_init(mm
, current
);
586 * Called when the last reference to the mm
587 * is dropped: either by a lazy thread or by
588 * mmput. Free the page directory and the mm.
590 void __mmdrop(struct mm_struct
*mm
)
592 BUG_ON(mm
== &init_mm
);
595 mmu_notifier_mm_destroy(mm
);
599 EXPORT_SYMBOL_GPL(__mmdrop
);
602 * Decrement the use count and release all resources for an mm.
604 void mmput(struct mm_struct
*mm
)
608 if (atomic_dec_and_test(&mm
->mm_users
)) {
609 uprobe_clear_state(mm
);
612 khugepaged_exit(mm
); /* must run before exit_mmap */
614 set_mm_exe_file(mm
, NULL
);
615 if (!list_empty(&mm
->mmlist
)) {
616 spin_lock(&mmlist_lock
);
617 list_del(&mm
->mmlist
);
618 spin_unlock(&mmlist_lock
);
621 module_put(mm
->binfmt
->module
);
625 EXPORT_SYMBOL_GPL(mmput
);
627 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
630 get_file(new_exe_file
);
633 mm
->exe_file
= new_exe_file
;
636 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
638 struct file
*exe_file
;
640 /* We need mmap_sem to protect against races with removal of exe_file */
641 down_read(&mm
->mmap_sem
);
642 exe_file
= mm
->exe_file
;
645 up_read(&mm
->mmap_sem
);
649 static void dup_mm_exe_file(struct mm_struct
*oldmm
, struct mm_struct
*newmm
)
651 /* It's safe to write the exe_file pointer without exe_file_lock because
652 * this is called during fork when the task is not yet in /proc */
653 newmm
->exe_file
= get_mm_exe_file(oldmm
);
657 * get_task_mm - acquire a reference to the task's mm
659 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
660 * this kernel workthread has transiently adopted a user mm with use_mm,
661 * to do its AIO) is not set and if so returns a reference to it, after
662 * bumping up the use count. User must release the mm via mmput()
663 * after use. Typically used by /proc and ptrace.
665 struct mm_struct
*get_task_mm(struct task_struct
*task
)
667 struct mm_struct
*mm
;
672 if (task
->flags
& PF_KTHREAD
)
675 atomic_inc(&mm
->mm_users
);
680 EXPORT_SYMBOL_GPL(get_task_mm
);
682 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
684 struct mm_struct
*mm
;
687 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
691 mm
= get_task_mm(task
);
692 if (mm
&& mm
!= current
->mm
&&
693 !ptrace_may_access(task
, mode
)) {
695 mm
= ERR_PTR(-EACCES
);
697 mutex_unlock(&task
->signal
->cred_guard_mutex
);
702 static void complete_vfork_done(struct task_struct
*tsk
)
704 struct completion
*vfork
;
707 vfork
= tsk
->vfork_done
;
709 tsk
->vfork_done
= NULL
;
715 static int wait_for_vfork_done(struct task_struct
*child
,
716 struct completion
*vfork
)
720 freezer_do_not_count();
721 killed
= wait_for_completion_killable(vfork
);
726 child
->vfork_done
= NULL
;
730 put_task_struct(child
);
734 /* Please note the differences between mmput and mm_release.
735 * mmput is called whenever we stop holding onto a mm_struct,
736 * error success whatever.
738 * mm_release is called after a mm_struct has been removed
739 * from the current process.
741 * This difference is important for error handling, when we
742 * only half set up a mm_struct for a new process and need to restore
743 * the old one. Because we mmput the new mm_struct before
744 * restoring the old one. . .
745 * Eric Biederman 10 January 1998
747 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
749 /* Get rid of any futexes when releasing the mm */
751 if (unlikely(tsk
->robust_list
)) {
752 exit_robust_list(tsk
);
753 tsk
->robust_list
= NULL
;
756 if (unlikely(tsk
->compat_robust_list
)) {
757 compat_exit_robust_list(tsk
);
758 tsk
->compat_robust_list
= NULL
;
761 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
762 exit_pi_state_list(tsk
);
765 uprobe_free_utask(tsk
);
767 /* Get rid of any cached register state */
768 deactivate_mm(tsk
, mm
);
771 * If we're exiting normally, clear a user-space tid field if
772 * requested. We leave this alone when dying by signal, to leave
773 * the value intact in a core dump, and to save the unnecessary
774 * trouble, say, a killed vfork parent shouldn't touch this mm.
775 * Userland only wants this done for a sys_exit.
777 if (tsk
->clear_child_tid
) {
778 if (!(tsk
->flags
& PF_SIGNALED
) &&
779 atomic_read(&mm
->mm_users
) > 1) {
781 * We don't check the error code - if userspace has
782 * not set up a proper pointer then tough luck.
784 put_user(0, tsk
->clear_child_tid
);
785 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
788 tsk
->clear_child_tid
= NULL
;
792 * All done, finally we can wake up parent and return this mm to him.
793 * Also kthread_stop() uses this completion for synchronization.
796 complete_vfork_done(tsk
);
800 * Allocate a new mm structure and copy contents from the
801 * mm structure of the passed in task structure.
803 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
805 struct mm_struct
*mm
, *oldmm
= current
->mm
;
815 memcpy(mm
, oldmm
, sizeof(*mm
));
818 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
819 mm
->pmd_huge_pte
= NULL
;
821 #ifdef CONFIG_NUMA_BALANCING
822 mm
->first_nid
= NUMA_PTE_SCAN_INIT
;
824 if (!mm_init(mm
, tsk
))
827 if (init_new_context(tsk
, mm
))
830 dup_mm_exe_file(oldmm
, mm
);
832 err
= dup_mmap(mm
, oldmm
);
836 mm
->hiwater_rss
= get_mm_rss(mm
);
837 mm
->hiwater_vm
= mm
->total_vm
;
839 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
845 /* don't put binfmt in mmput, we haven't got module yet */
854 * If init_new_context() failed, we cannot use mmput() to free the mm
855 * because it calls destroy_context()
862 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
864 struct mm_struct
*mm
, *oldmm
;
867 tsk
->min_flt
= tsk
->maj_flt
= 0;
868 tsk
->nvcsw
= tsk
->nivcsw
= 0;
869 #ifdef CONFIG_DETECT_HUNG_TASK
870 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
874 tsk
->active_mm
= NULL
;
877 * Are we cloning a kernel thread?
879 * We need to steal a active VM for that..
885 if (clone_flags
& CLONE_VM
) {
886 atomic_inc(&oldmm
->mm_users
);
905 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
907 struct fs_struct
*fs
= current
->fs
;
908 if (clone_flags
& CLONE_FS
) {
909 /* tsk->fs is already what we want */
910 spin_lock(&fs
->lock
);
912 spin_unlock(&fs
->lock
);
916 spin_unlock(&fs
->lock
);
919 tsk
->fs
= copy_fs_struct(fs
);
925 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
927 struct files_struct
*oldf
, *newf
;
931 * A background process may not have any files ...
933 oldf
= current
->files
;
937 if (clone_flags
& CLONE_FILES
) {
938 atomic_inc(&oldf
->count
);
942 newf
= dup_fd(oldf
, &error
);
952 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
955 struct io_context
*ioc
= current
->io_context
;
956 struct io_context
*new_ioc
;
961 * Share io context with parent, if CLONE_IO is set
963 if (clone_flags
& CLONE_IO
) {
965 tsk
->io_context
= ioc
;
966 } else if (ioprio_valid(ioc
->ioprio
)) {
967 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
968 if (unlikely(!new_ioc
))
971 new_ioc
->ioprio
= ioc
->ioprio
;
972 put_io_context(new_ioc
);
978 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
980 struct sighand_struct
*sig
;
982 if (clone_flags
& CLONE_SIGHAND
) {
983 atomic_inc(¤t
->sighand
->count
);
986 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
987 rcu_assign_pointer(tsk
->sighand
, sig
);
990 atomic_set(&sig
->count
, 1);
991 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
995 void __cleanup_sighand(struct sighand_struct
*sighand
)
997 if (atomic_dec_and_test(&sighand
->count
)) {
998 signalfd_cleanup(sighand
);
999 kmem_cache_free(sighand_cachep
, sighand
);
1005 * Initialize POSIX timer handling for a thread group.
1007 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
1009 unsigned long cpu_limit
;
1011 /* Thread group counters. */
1012 thread_group_cputime_init(sig
);
1014 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1015 if (cpu_limit
!= RLIM_INFINITY
) {
1016 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1017 sig
->cputimer
.running
= 1;
1020 /* The timer lists. */
1021 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1022 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1023 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1026 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1028 struct signal_struct
*sig
;
1030 if (clone_flags
& CLONE_THREAD
)
1033 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1038 sig
->nr_threads
= 1;
1039 atomic_set(&sig
->live
, 1);
1040 atomic_set(&sig
->sigcnt
, 1);
1042 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1043 sig
->thread_head
= (struct list_head
)LIST_HEAD_INIT(tsk
->thread_node
);
1044 tsk
->thread_node
= (struct list_head
)LIST_HEAD_INIT(sig
->thread_head
);
1046 init_waitqueue_head(&sig
->wait_chldexit
);
1047 sig
->curr_target
= tsk
;
1048 init_sigpending(&sig
->shared_pending
);
1049 INIT_LIST_HEAD(&sig
->posix_timers
);
1051 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1052 sig
->real_timer
.function
= it_real_fn
;
1054 task_lock(current
->group_leader
);
1055 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1056 task_unlock(current
->group_leader
);
1058 posix_cpu_timers_init_group(sig
);
1060 tty_audit_fork(sig
);
1061 sched_autogroup_fork(sig
);
1063 #ifdef CONFIG_CGROUPS
1064 init_rwsem(&sig
->group_rwsem
);
1067 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1068 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1070 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1071 current
->signal
->is_child_subreaper
;
1073 mutex_init(&sig
->cred_guard_mutex
);
1078 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
1080 unsigned long new_flags
= p
->flags
;
1082 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
1083 new_flags
|= PF_FORKNOEXEC
;
1084 p
->flags
= new_flags
;
1087 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1089 current
->clear_child_tid
= tidptr
;
1091 return task_pid_vnr(current
);
1094 static void rt_mutex_init_task(struct task_struct
*p
)
1096 raw_spin_lock_init(&p
->pi_lock
);
1097 #ifdef CONFIG_RT_MUTEXES
1098 plist_head_init(&p
->pi_waiters
);
1099 p
->pi_blocked_on
= NULL
;
1103 #ifdef CONFIG_MM_OWNER
1104 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1108 #endif /* CONFIG_MM_OWNER */
1111 * Initialize POSIX timer handling for a single task.
1113 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1115 tsk
->cputime_expires
.prof_exp
= 0;
1116 tsk
->cputime_expires
.virt_exp
= 0;
1117 tsk
->cputime_expires
.sched_exp
= 0;
1118 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1119 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1120 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1124 init_task_pid(struct task_struct
*task
, enum pid_type type
, struct pid
*pid
)
1126 task
->pids
[type
].pid
= pid
;
1130 * This creates a new process as a copy of the old one,
1131 * but does not actually start it yet.
1133 * It copies the registers, and all the appropriate
1134 * parts of the process environment (as per the clone
1135 * flags). The actual kick-off is left to the caller.
1137 static struct task_struct
*copy_process(unsigned long clone_flags
,
1138 unsigned long stack_start
,
1139 unsigned long stack_size
,
1140 int __user
*child_tidptr
,
1145 struct task_struct
*p
;
1147 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1148 return ERR_PTR(-EINVAL
);
1150 if ((clone_flags
& (CLONE_NEWUSER
|CLONE_FS
)) == (CLONE_NEWUSER
|CLONE_FS
))
1151 return ERR_PTR(-EINVAL
);
1154 * Thread groups must share signals as well, and detached threads
1155 * can only be started up within the thread group.
1157 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1158 return ERR_PTR(-EINVAL
);
1161 * Shared signal handlers imply shared VM. By way of the above,
1162 * thread groups also imply shared VM. Blocking this case allows
1163 * for various simplifications in other code.
1165 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1166 return ERR_PTR(-EINVAL
);
1169 * Siblings of global init remain as zombies on exit since they are
1170 * not reaped by their parent (swapper). To solve this and to avoid
1171 * multi-rooted process trees, prevent global and container-inits
1172 * from creating siblings.
1174 if ((clone_flags
& CLONE_PARENT
) &&
1175 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1176 return ERR_PTR(-EINVAL
);
1179 * If the new process will be in a different pid or user namespace
1180 * do not allow it to share a thread group or signal handlers or
1181 * parent with the forking task.
1183 if (clone_flags
& CLONE_SIGHAND
) {
1184 if ((clone_flags
& (CLONE_NEWUSER
| CLONE_NEWPID
)) ||
1185 (task_active_pid_ns(current
) !=
1186 current
->nsproxy
->pid_ns_for_children
))
1187 return ERR_PTR(-EINVAL
);
1190 retval
= security_task_create(clone_flags
);
1195 p
= dup_task_struct(current
);
1199 ftrace_graph_init_task(p
);
1200 get_seccomp_filter(p
);
1202 rt_mutex_init_task(p
);
1204 #ifdef CONFIG_PROVE_LOCKING
1205 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1206 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1209 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1210 task_rlimit(p
, RLIMIT_NPROC
)) {
1211 if (p
->real_cred
->user
!= INIT_USER
&&
1212 !capable(CAP_SYS_RESOURCE
) && !capable(CAP_SYS_ADMIN
))
1215 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1217 retval
= copy_creds(p
, clone_flags
);
1222 * If multiple threads are within copy_process(), then this check
1223 * triggers too late. This doesn't hurt, the check is only there
1224 * to stop root fork bombs.
1227 if (nr_threads
>= max_threads
)
1228 goto bad_fork_cleanup_count
;
1230 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1231 goto bad_fork_cleanup_count
;
1234 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1235 copy_flags(clone_flags
, p
);
1236 INIT_LIST_HEAD(&p
->children
);
1237 INIT_LIST_HEAD(&p
->sibling
);
1238 rcu_copy_process(p
);
1239 p
->vfork_done
= NULL
;
1240 spin_lock_init(&p
->alloc_lock
);
1242 init_sigpending(&p
->pending
);
1244 p
->utime
= p
->stime
= p
->gtime
= 0;
1245 p
->utimescaled
= p
->stimescaled
= 0;
1246 #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
1247 p
->prev_cputime
.utime
= p
->prev_cputime
.stime
= 0;
1249 #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
1250 seqlock_init(&p
->vtime_seqlock
);
1252 p
->vtime_snap_whence
= VTIME_SLEEPING
;
1255 #if defined(SPLIT_RSS_COUNTING)
1256 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1259 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1261 task_io_accounting_init(&p
->ioac
);
1262 acct_clear_integrals(p
);
1264 posix_cpu_timers_init(p
);
1266 do_posix_clock_monotonic_gettime(&p
->start_time
);
1267 p
->real_start_time
= p
->start_time
;
1268 monotonic_to_bootbased(&p
->real_start_time
);
1269 p
->io_context
= NULL
;
1270 p
->audit_context
= NULL
;
1271 if (clone_flags
& CLONE_THREAD
)
1272 threadgroup_change_begin(current
);
1275 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1276 if (IS_ERR(p
->mempolicy
)) {
1277 retval
= PTR_ERR(p
->mempolicy
);
1278 p
->mempolicy
= NULL
;
1279 goto bad_fork_cleanup_cgroup
;
1281 mpol_fix_fork_child_flag(p
);
1283 #ifdef CONFIG_CPUSETS
1284 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1285 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1286 seqcount_init(&p
->mems_allowed_seq
);
1288 #ifdef CONFIG_TRACE_IRQFLAGS
1290 p
->hardirqs_enabled
= 0;
1291 p
->hardirq_enable_ip
= 0;
1292 p
->hardirq_enable_event
= 0;
1293 p
->hardirq_disable_ip
= _THIS_IP_
;
1294 p
->hardirq_disable_event
= 0;
1295 p
->softirqs_enabled
= 1;
1296 p
->softirq_enable_ip
= _THIS_IP_
;
1297 p
->softirq_enable_event
= 0;
1298 p
->softirq_disable_ip
= 0;
1299 p
->softirq_disable_event
= 0;
1300 p
->hardirq_context
= 0;
1301 p
->softirq_context
= 0;
1303 #ifdef CONFIG_LOCKDEP
1304 p
->lockdep_depth
= 0; /* no locks held yet */
1305 p
->curr_chain_key
= 0;
1306 p
->lockdep_recursion
= 0;
1309 #ifdef CONFIG_DEBUG_MUTEXES
1310 p
->blocked_on
= NULL
; /* not blocked yet */
1313 p
->memcg_batch
.do_batch
= 0;
1314 p
->memcg_batch
.memcg
= NULL
;
1316 #ifdef CONFIG_BCACHE
1317 p
->sequential_io
= 0;
1318 p
->sequential_io_avg
= 0;
1321 /* Perform scheduler related setup. Assign this task to a CPU. */
1324 retval
= perf_event_init_task(p
);
1326 goto bad_fork_cleanup_policy
;
1327 retval
= audit_alloc(p
);
1329 goto bad_fork_cleanup_policy
;
1330 /* copy all the process information */
1331 retval
= copy_semundo(clone_flags
, p
);
1333 goto bad_fork_cleanup_audit
;
1334 retval
= copy_files(clone_flags
, p
);
1336 goto bad_fork_cleanup_semundo
;
1337 retval
= copy_fs(clone_flags
, p
);
1339 goto bad_fork_cleanup_files
;
1340 retval
= copy_sighand(clone_flags
, p
);
1342 goto bad_fork_cleanup_fs
;
1343 retval
= copy_signal(clone_flags
, p
);
1345 goto bad_fork_cleanup_sighand
;
1346 retval
= copy_mm(clone_flags
, p
);
1348 goto bad_fork_cleanup_signal
;
1349 retval
= copy_namespaces(clone_flags
, p
);
1351 goto bad_fork_cleanup_mm
;
1352 retval
= copy_io(clone_flags
, p
);
1354 goto bad_fork_cleanup_namespaces
;
1355 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
);
1357 goto bad_fork_cleanup_io
;
1359 if (pid
!= &init_struct_pid
) {
1361 pid
= alloc_pid(p
->nsproxy
->pid_ns_for_children
);
1363 goto bad_fork_cleanup_io
;
1366 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1368 * Clear TID on mm_release()?
1370 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1375 p
->robust_list
= NULL
;
1376 #ifdef CONFIG_COMPAT
1377 p
->compat_robust_list
= NULL
;
1379 INIT_LIST_HEAD(&p
->pi_state_list
);
1380 p
->pi_state_cache
= NULL
;
1382 uprobe_copy_process(p
);
1384 * sigaltstack should be cleared when sharing the same VM
1386 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1387 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1390 * Syscall tracing and stepping should be turned off in the
1391 * child regardless of CLONE_PTRACE.
1393 user_disable_single_step(p
);
1394 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1395 #ifdef TIF_SYSCALL_EMU
1396 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1398 clear_all_latency_tracing(p
);
1400 /* ok, now we should be set up.. */
1401 p
->pid
= pid_nr(pid
);
1402 if (clone_flags
& CLONE_THREAD
) {
1403 p
->exit_signal
= -1;
1404 p
->group_leader
= current
->group_leader
;
1405 p
->tgid
= current
->tgid
;
1407 if (clone_flags
& CLONE_PARENT
)
1408 p
->exit_signal
= current
->group_leader
->exit_signal
;
1410 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1411 p
->group_leader
= p
;
1415 p
->pdeath_signal
= 0;
1419 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1420 p
->dirty_paused_when
= 0;
1422 INIT_LIST_HEAD(&p
->thread_group
);
1423 p
->task_works
= NULL
;
1426 * Make it visible to the rest of the system, but dont wake it up yet.
1427 * Need tasklist lock for parent etc handling!
1429 write_lock_irq(&tasklist_lock
);
1431 /* CLONE_PARENT re-uses the old parent */
1432 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1433 p
->real_parent
= current
->real_parent
;
1434 p
->parent_exec_id
= current
->parent_exec_id
;
1436 p
->real_parent
= current
;
1437 p
->parent_exec_id
= current
->self_exec_id
;
1440 spin_lock(¤t
->sighand
->siglock
);
1443 * Process group and session signals need to be delivered to just the
1444 * parent before the fork or both the parent and the child after the
1445 * fork. Restart if a signal comes in before we add the new process to
1446 * it's process group.
1447 * A fatal signal pending means that current will exit, so the new
1448 * thread can't slip out of an OOM kill (or normal SIGKILL).
1450 recalc_sigpending();
1451 if (signal_pending(current
)) {
1452 spin_unlock(¤t
->sighand
->siglock
);
1453 write_unlock_irq(&tasklist_lock
);
1454 retval
= -ERESTARTNOINTR
;
1455 goto bad_fork_free_pid
;
1458 if (likely(p
->pid
)) {
1459 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1461 init_task_pid(p
, PIDTYPE_PID
, pid
);
1462 if (thread_group_leader(p
)) {
1463 init_task_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1464 init_task_pid(p
, PIDTYPE_SID
, task_session(current
));
1466 if (is_child_reaper(pid
)) {
1467 ns_of_pid(pid
)->child_reaper
= p
;
1468 p
->signal
->flags
|= SIGNAL_UNKILLABLE
;
1471 p
->signal
->leader_pid
= pid
;
1472 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1473 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1474 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1475 attach_pid(p
, PIDTYPE_PGID
);
1476 attach_pid(p
, PIDTYPE_SID
);
1477 __this_cpu_inc(process_counts
);
1479 current
->signal
->nr_threads
++;
1480 atomic_inc(¤t
->signal
->live
);
1481 atomic_inc(¤t
->signal
->sigcnt
);
1482 list_add_tail_rcu(&p
->thread_group
,
1483 &p
->group_leader
->thread_group
);
1484 list_add_tail_rcu(&p
->thread_node
,
1485 &p
->signal
->thread_head
);
1487 attach_pid(p
, PIDTYPE_PID
);
1492 spin_unlock(¤t
->sighand
->siglock
);
1493 syscall_tracepoint_update(p
);
1494 write_unlock_irq(&tasklist_lock
);
1496 proc_fork_connector(p
);
1497 cgroup_post_fork(p
);
1498 if (clone_flags
& CLONE_THREAD
)
1499 threadgroup_change_end(current
);
1502 trace_task_newtask(p
, clone_flags
);
1507 if (pid
!= &init_struct_pid
)
1509 bad_fork_cleanup_io
:
1512 bad_fork_cleanup_namespaces
:
1513 exit_task_namespaces(p
);
1514 bad_fork_cleanup_mm
:
1517 bad_fork_cleanup_signal
:
1518 if (!(clone_flags
& CLONE_THREAD
))
1519 free_signal_struct(p
->signal
);
1520 bad_fork_cleanup_sighand
:
1521 __cleanup_sighand(p
->sighand
);
1522 bad_fork_cleanup_fs
:
1523 exit_fs(p
); /* blocking */
1524 bad_fork_cleanup_files
:
1525 exit_files(p
); /* blocking */
1526 bad_fork_cleanup_semundo
:
1528 bad_fork_cleanup_audit
:
1530 bad_fork_cleanup_policy
:
1531 perf_event_free_task(p
);
1533 mpol_put(p
->mempolicy
);
1534 bad_fork_cleanup_cgroup
:
1536 if (clone_flags
& CLONE_THREAD
)
1537 threadgroup_change_end(current
);
1539 delayacct_tsk_free(p
);
1540 module_put(task_thread_info(p
)->exec_domain
->module
);
1541 bad_fork_cleanup_count
:
1542 atomic_dec(&p
->cred
->user
->processes
);
1547 return ERR_PTR(retval
);
1550 static inline void init_idle_pids(struct pid_link
*links
)
1554 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1555 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1556 links
[type
].pid
= &init_struct_pid
;
1560 struct task_struct
*fork_idle(int cpu
)
1562 struct task_struct
*task
;
1563 task
= copy_process(CLONE_VM
, 0, 0, NULL
, &init_struct_pid
, 0);
1564 if (!IS_ERR(task
)) {
1565 init_idle_pids(task
->pids
);
1566 init_idle(task
, cpu
);
1573 * Ok, this is the main fork-routine.
1575 * It copies the process, and if successful kick-starts
1576 * it and waits for it to finish using the VM if required.
1578 long do_fork(unsigned long clone_flags
,
1579 unsigned long stack_start
,
1580 unsigned long stack_size
,
1581 int __user
*parent_tidptr
,
1582 int __user
*child_tidptr
)
1584 struct task_struct
*p
;
1589 * Determine whether and which event to report to ptracer. When
1590 * called from kernel_thread or CLONE_UNTRACED is explicitly
1591 * requested, no event is reported; otherwise, report if the event
1592 * for the type of forking is enabled.
1594 if (!(clone_flags
& CLONE_UNTRACED
)) {
1595 if (clone_flags
& CLONE_VFORK
)
1596 trace
= PTRACE_EVENT_VFORK
;
1597 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1598 trace
= PTRACE_EVENT_CLONE
;
1600 trace
= PTRACE_EVENT_FORK
;
1602 if (likely(!ptrace_event_enabled(current
, trace
)))
1606 p
= copy_process(clone_flags
, stack_start
, stack_size
,
1607 child_tidptr
, NULL
, trace
);
1609 * Do this prior waking up the new thread - the thread pointer
1610 * might get invalid after that point, if the thread exits quickly.
1613 struct completion vfork
;
1616 trace_sched_process_fork(current
, p
);
1618 pid
= get_task_pid(p
, PIDTYPE_PID
);
1621 if (clone_flags
& CLONE_PARENT_SETTID
)
1622 put_user(nr
, parent_tidptr
);
1624 if (clone_flags
& CLONE_VFORK
) {
1625 p
->vfork_done
= &vfork
;
1626 init_completion(&vfork
);
1630 wake_up_new_task(p
);
1632 /* forking complete and child started to run, tell ptracer */
1633 if (unlikely(trace
))
1634 ptrace_event_pid(trace
, pid
);
1636 if (clone_flags
& CLONE_VFORK
) {
1637 if (!wait_for_vfork_done(p
, &vfork
))
1638 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE
, pid
);
1649 * Create a kernel thread.
1651 pid_t
kernel_thread(int (*fn
)(void *), void *arg
, unsigned long flags
)
1653 return do_fork(flags
|CLONE_VM
|CLONE_UNTRACED
, (unsigned long)fn
,
1654 (unsigned long)arg
, NULL
, NULL
);
1657 #ifdef __ARCH_WANT_SYS_FORK
1658 SYSCALL_DEFINE0(fork
)
1661 return do_fork(SIGCHLD
, 0, 0, NULL
, NULL
);
1663 /* can not support in nommu mode */
1669 #ifdef __ARCH_WANT_SYS_VFORK
1670 SYSCALL_DEFINE0(vfork
)
1672 return do_fork(CLONE_VFORK
| CLONE_VM
| SIGCHLD
, 0,
1677 #ifdef __ARCH_WANT_SYS_CLONE
1678 #ifdef CONFIG_CLONE_BACKWARDS
1679 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1680 int __user
*, parent_tidptr
,
1682 int __user
*, child_tidptr
)
1683 #elif defined(CONFIG_CLONE_BACKWARDS2)
1684 SYSCALL_DEFINE5(clone
, unsigned long, newsp
, unsigned long, clone_flags
,
1685 int __user
*, parent_tidptr
,
1686 int __user
*, child_tidptr
,
1688 #elif defined(CONFIG_CLONE_BACKWARDS3)
1689 SYSCALL_DEFINE6(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1691 int __user
*, parent_tidptr
,
1692 int __user
*, child_tidptr
,
1695 SYSCALL_DEFINE5(clone
, unsigned long, clone_flags
, unsigned long, newsp
,
1696 int __user
*, parent_tidptr
,
1697 int __user
*, child_tidptr
,
1701 return do_fork(clone_flags
, newsp
, 0, parent_tidptr
, child_tidptr
);
1705 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1706 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1709 static void sighand_ctor(void *data
)
1711 struct sighand_struct
*sighand
= data
;
1713 spin_lock_init(&sighand
->siglock
);
1714 init_waitqueue_head(&sighand
->signalfd_wqh
);
1717 void __init
proc_caches_init(void)
1719 sighand_cachep
= kmem_cache_create("sighand_cache",
1720 sizeof(struct sighand_struct
), 0,
1721 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1722 SLAB_NOTRACK
, sighand_ctor
);
1723 signal_cachep
= kmem_cache_create("signal_cache",
1724 sizeof(struct signal_struct
), 0,
1725 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1726 files_cachep
= kmem_cache_create("files_cache",
1727 sizeof(struct files_struct
), 0,
1728 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1729 fs_cachep
= kmem_cache_create("fs_cache",
1730 sizeof(struct fs_struct
), 0,
1731 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1733 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1734 * whole struct cpumask for the OFFSTACK case. We could change
1735 * this to *only* allocate as much of it as required by the
1736 * maximum number of CPU's we can ever have. The cpumask_allocation
1737 * is at the end of the structure, exactly for that reason.
1739 mm_cachep
= kmem_cache_create("mm_struct",
1740 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1741 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1742 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1744 nsproxy_cache_init();
1748 * Check constraints on flags passed to the unshare system call.
1750 static int check_unshare_flags(unsigned long unshare_flags
)
1752 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1753 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1754 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
|
1755 CLONE_NEWUSER
|CLONE_NEWPID
))
1758 * Not implemented, but pretend it works if there is nothing to
1759 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1760 * needs to unshare vm.
1762 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
1763 /* FIXME: get_task_mm() increments ->mm_users */
1764 if (atomic_read(¤t
->mm
->mm_users
) > 1)
1772 * Unshare the filesystem structure if it is being shared
1774 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1776 struct fs_struct
*fs
= current
->fs
;
1778 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1781 /* don't need lock here; in the worst case we'll do useless copy */
1785 *new_fsp
= copy_fs_struct(fs
);
1793 * Unshare file descriptor table if it is being shared
1795 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1797 struct files_struct
*fd
= current
->files
;
1800 if ((unshare_flags
& CLONE_FILES
) &&
1801 (fd
&& atomic_read(&fd
->count
) > 1)) {
1802 *new_fdp
= dup_fd(fd
, &error
);
1811 * unshare allows a process to 'unshare' part of the process
1812 * context which was originally shared using clone. copy_*
1813 * functions used by do_fork() cannot be used here directly
1814 * because they modify an inactive task_struct that is being
1815 * constructed. Here we are modifying the current, active,
1818 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1820 struct fs_struct
*fs
, *new_fs
= NULL
;
1821 struct files_struct
*fd
, *new_fd
= NULL
;
1822 struct cred
*new_cred
= NULL
;
1823 struct nsproxy
*new_nsproxy
= NULL
;
1828 * If unsharing a user namespace must also unshare the thread.
1830 if (unshare_flags
& CLONE_NEWUSER
)
1831 unshare_flags
|= CLONE_THREAD
| CLONE_FS
;
1833 * If unsharing a thread from a thread group, must also unshare vm.
1835 if (unshare_flags
& CLONE_THREAD
)
1836 unshare_flags
|= CLONE_VM
;
1838 * If unsharing vm, must also unshare signal handlers.
1840 if (unshare_flags
& CLONE_VM
)
1841 unshare_flags
|= CLONE_SIGHAND
;
1843 * If unsharing namespace, must also unshare filesystem information.
1845 if (unshare_flags
& CLONE_NEWNS
)
1846 unshare_flags
|= CLONE_FS
;
1848 err
= check_unshare_flags(unshare_flags
);
1850 goto bad_unshare_out
;
1852 * CLONE_NEWIPC must also detach from the undolist: after switching
1853 * to a new ipc namespace, the semaphore arrays from the old
1854 * namespace are unreachable.
1856 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1858 err
= unshare_fs(unshare_flags
, &new_fs
);
1860 goto bad_unshare_out
;
1861 err
= unshare_fd(unshare_flags
, &new_fd
);
1863 goto bad_unshare_cleanup_fs
;
1864 err
= unshare_userns(unshare_flags
, &new_cred
);
1866 goto bad_unshare_cleanup_fd
;
1867 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
,
1870 goto bad_unshare_cleanup_cred
;
1872 if (new_fs
|| new_fd
|| do_sysvsem
|| new_cred
|| new_nsproxy
) {
1875 * CLONE_SYSVSEM is equivalent to sys_exit().
1881 switch_task_namespaces(current
, new_nsproxy
);
1887 spin_lock(&fs
->lock
);
1888 current
->fs
= new_fs
;
1893 spin_unlock(&fs
->lock
);
1897 fd
= current
->files
;
1898 current
->files
= new_fd
;
1902 task_unlock(current
);
1905 /* Install the new user namespace */
1906 commit_creds(new_cred
);
1911 bad_unshare_cleanup_cred
:
1914 bad_unshare_cleanup_fd
:
1916 put_files_struct(new_fd
);
1918 bad_unshare_cleanup_fs
:
1920 free_fs_struct(new_fs
);
1927 * Helper to unshare the files of the current task.
1928 * We don't want to expose copy_files internals to
1929 * the exec layer of the kernel.
1932 int unshare_files(struct files_struct
**displaced
)
1934 struct task_struct
*task
= current
;
1935 struct files_struct
*copy
= NULL
;
1938 error
= unshare_fd(CLONE_FILES
, ©
);
1939 if (error
|| !copy
) {
1943 *displaced
= task
->files
;