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/swap.h>
38 #include <linux/syscalls.h>
39 #include <linux/jiffies.h>
40 #include <linux/futex.h>
41 #include <linux/compat.h>
42 #include <linux/kthread.h>
43 #include <linux/task_io_accounting_ops.h>
44 #include <linux/rcupdate.h>
45 #include <linux/ptrace.h>
46 #include <linux/mount.h>
47 #include <linux/audit.h>
48 #include <linux/memcontrol.h>
49 #include <linux/ftrace.h>
50 #include <linux/proc_fs.h>
51 #include <linux/profile.h>
52 #include <linux/rmap.h>
53 #include <linux/ksm.h>
54 #include <linux/acct.h>
55 #include <linux/tsacct_kern.h>
56 #include <linux/cn_proc.h>
57 #include <linux/freezer.h>
58 #include <linux/delayacct.h>
59 #include <linux/taskstats_kern.h>
60 #include <linux/random.h>
61 #include <linux/tty.h>
62 #include <linux/blkdev.h>
63 #include <linux/fs_struct.h>
64 #include <linux/magic.h>
65 #include <linux/perf_event.h>
66 #include <linux/posix-timers.h>
67 #include <linux/user-return-notifier.h>
68 #include <linux/oom.h>
69 #include <linux/khugepaged.h>
70 #include <linux/signalfd.h>
72 #include <asm/pgtable.h>
73 #include <asm/pgalloc.h>
74 #include <asm/uaccess.h>
75 #include <asm/mmu_context.h>
76 #include <asm/cacheflush.h>
77 #include <asm/tlbflush.h>
79 #include <trace/events/sched.h>
81 #define CREATE_TRACE_POINTS
82 #include <trace/events/task.h>
85 * Protected counters by write_lock_irq(&tasklist_lock)
87 unsigned long total_forks
; /* Handle normal Linux uptimes. */
88 int nr_threads
; /* The idle threads do not count.. */
90 int max_threads
; /* tunable limit on nr_threads */
92 DEFINE_PER_CPU(unsigned long, process_counts
) = 0;
94 __cacheline_aligned
DEFINE_RWLOCK(tasklist_lock
); /* outer */
96 #ifdef CONFIG_PROVE_RCU
97 int lockdep_tasklist_lock_is_held(void)
99 return lockdep_is_held(&tasklist_lock
);
101 EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held
);
102 #endif /* #ifdef CONFIG_PROVE_RCU */
104 int nr_processes(void)
109 for_each_possible_cpu(cpu
)
110 total
+= per_cpu(process_counts
, cpu
);
115 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
116 # define alloc_task_struct_node(node) \
117 kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node)
118 # define free_task_struct(tsk) \
119 kmem_cache_free(task_struct_cachep, (tsk))
120 static struct kmem_cache
*task_struct_cachep
;
123 #ifndef __HAVE_ARCH_THREAD_INFO_ALLOCATOR
124 static struct thread_info
*alloc_thread_info_node(struct task_struct
*tsk
,
127 #ifdef CONFIG_DEBUG_STACK_USAGE
128 gfp_t mask
= GFP_KERNEL
| __GFP_ZERO
;
130 gfp_t mask
= GFP_KERNEL
;
132 struct page
*page
= alloc_pages_node(node
, mask
, THREAD_SIZE_ORDER
);
134 return page
? page_address(page
) : NULL
;
137 static inline void free_thread_info(struct thread_info
*ti
)
139 free_pages((unsigned long)ti
, THREAD_SIZE_ORDER
);
143 /* SLAB cache for signal_struct structures (tsk->signal) */
144 static struct kmem_cache
*signal_cachep
;
146 /* SLAB cache for sighand_struct structures (tsk->sighand) */
147 struct kmem_cache
*sighand_cachep
;
149 /* SLAB cache for files_struct structures (tsk->files) */
150 struct kmem_cache
*files_cachep
;
152 /* SLAB cache for fs_struct structures (tsk->fs) */
153 struct kmem_cache
*fs_cachep
;
155 /* SLAB cache for vm_area_struct structures */
156 struct kmem_cache
*vm_area_cachep
;
158 /* SLAB cache for mm_struct structures (tsk->mm) */
159 static struct kmem_cache
*mm_cachep
;
161 static void account_kernel_stack(struct thread_info
*ti
, int account
)
163 struct zone
*zone
= page_zone(virt_to_page(ti
));
165 mod_zone_page_state(zone
, NR_KERNEL_STACK
, account
);
168 void free_task(struct task_struct
*tsk
)
170 account_kernel_stack(tsk
->stack
, -1);
171 free_thread_info(tsk
->stack
);
172 rt_mutex_debug_task_free(tsk
);
173 ftrace_graph_exit_task(tsk
);
174 free_task_struct(tsk
);
176 EXPORT_SYMBOL(free_task
);
178 static inline void free_signal_struct(struct signal_struct
*sig
)
180 taskstats_tgid_free(sig
);
181 sched_autogroup_exit(sig
);
182 kmem_cache_free(signal_cachep
, sig
);
185 static inline void put_signal_struct(struct signal_struct
*sig
)
187 if (atomic_dec_and_test(&sig
->sigcnt
))
188 free_signal_struct(sig
);
191 void __put_task_struct(struct task_struct
*tsk
)
193 WARN_ON(!tsk
->exit_state
);
194 WARN_ON(atomic_read(&tsk
->usage
));
195 WARN_ON(tsk
== current
);
197 security_task_free(tsk
);
199 delayacct_tsk_free(tsk
);
200 put_signal_struct(tsk
->signal
);
202 if (!profile_handoff_task(tsk
))
205 EXPORT_SYMBOL_GPL(__put_task_struct
);
208 * macro override instead of weak attribute alias, to workaround
209 * gcc 4.1.0 and 4.1.1 bugs with weak attribute and empty functions.
211 #ifndef arch_task_cache_init
212 #define arch_task_cache_init()
215 void __init
fork_init(unsigned long mempages
)
217 #ifndef __HAVE_ARCH_TASK_STRUCT_ALLOCATOR
218 #ifndef ARCH_MIN_TASKALIGN
219 #define ARCH_MIN_TASKALIGN L1_CACHE_BYTES
221 /* create a slab on which task_structs can be allocated */
223 kmem_cache_create("task_struct", sizeof(struct task_struct
),
224 ARCH_MIN_TASKALIGN
, SLAB_PANIC
| SLAB_NOTRACK
, NULL
);
227 /* do the arch specific task caches init */
228 arch_task_cache_init();
231 * The default maximum number of threads is set to a safe
232 * value: the thread structures can take up at most half
235 max_threads
= mempages
/ (8 * THREAD_SIZE
/ PAGE_SIZE
);
238 * we need to allow at least 20 threads to boot a system
240 if (max_threads
< 20)
243 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_cur
= max_threads
/2;
244 init_task
.signal
->rlim
[RLIMIT_NPROC
].rlim_max
= max_threads
/2;
245 init_task
.signal
->rlim
[RLIMIT_SIGPENDING
] =
246 init_task
.signal
->rlim
[RLIMIT_NPROC
];
249 int __attribute__((weak
)) arch_dup_task_struct(struct task_struct
*dst
,
250 struct task_struct
*src
)
256 static struct task_struct
*dup_task_struct(struct task_struct
*orig
)
258 struct task_struct
*tsk
;
259 struct thread_info
*ti
;
260 unsigned long *stackend
;
261 int node
= tsk_fork_get_node(orig
);
264 prepare_to_copy(orig
);
266 tsk
= alloc_task_struct_node(node
);
270 ti
= alloc_thread_info_node(tsk
, node
);
272 free_task_struct(tsk
);
276 err
= arch_dup_task_struct(tsk
, orig
);
282 setup_thread_stack(tsk
, orig
);
283 clear_user_return_notifier(tsk
);
284 clear_tsk_need_resched(tsk
);
285 stackend
= end_of_stack(tsk
);
286 *stackend
= STACK_END_MAGIC
; /* for overflow detection */
288 #ifdef CONFIG_CC_STACKPROTECTOR
289 tsk
->stack_canary
= get_random_int();
293 * One for us, one for whoever does the "release_task()" (usually
296 atomic_set(&tsk
->usage
, 2);
297 #ifdef CONFIG_BLK_DEV_IO_TRACE
300 tsk
->splice_pipe
= NULL
;
302 account_kernel_stack(ti
, 1);
307 free_thread_info(ti
);
308 free_task_struct(tsk
);
313 static int dup_mmap(struct mm_struct
*mm
, struct mm_struct
*oldmm
)
315 struct vm_area_struct
*mpnt
, *tmp
, *prev
, **pprev
;
316 struct rb_node
**rb_link
, *rb_parent
;
318 unsigned long charge
;
319 struct mempolicy
*pol
;
321 down_write(&oldmm
->mmap_sem
);
322 flush_cache_dup_mm(oldmm
);
324 * Not linked in yet - no deadlock potential:
326 down_write_nested(&mm
->mmap_sem
, SINGLE_DEPTH_NESTING
);
330 mm
->mmap_cache
= NULL
;
331 mm
->free_area_cache
= oldmm
->mmap_base
;
332 mm
->cached_hole_size
= ~0UL;
334 cpumask_clear(mm_cpumask(mm
));
336 rb_link
= &mm
->mm_rb
.rb_node
;
339 retval
= ksm_fork(mm
, oldmm
);
342 retval
= khugepaged_fork(mm
, oldmm
);
347 for (mpnt
= oldmm
->mmap
; mpnt
; mpnt
= mpnt
->vm_next
) {
350 if (mpnt
->vm_flags
& VM_DONTCOPY
) {
351 long pages
= vma_pages(mpnt
);
352 mm
->total_vm
-= pages
;
353 vm_stat_account(mm
, mpnt
->vm_flags
, mpnt
->vm_file
,
358 if (mpnt
->vm_flags
& VM_ACCOUNT
) {
359 unsigned int len
= (mpnt
->vm_end
- mpnt
->vm_start
) >> PAGE_SHIFT
;
360 if (security_vm_enough_memory_mm(oldmm
, len
)) /* sic */
364 tmp
= kmem_cache_alloc(vm_area_cachep
, GFP_KERNEL
);
368 INIT_LIST_HEAD(&tmp
->anon_vma_chain
);
369 pol
= mpol_dup(vma_policy(mpnt
));
370 retval
= PTR_ERR(pol
);
372 goto fail_nomem_policy
;
373 vma_set_policy(tmp
, pol
);
375 if (anon_vma_fork(tmp
, mpnt
))
376 goto fail_nomem_anon_vma_fork
;
377 tmp
->vm_flags
&= ~VM_LOCKED
;
378 tmp
->vm_next
= tmp
->vm_prev
= NULL
;
381 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
382 struct address_space
*mapping
= file
->f_mapping
;
385 if (tmp
->vm_flags
& VM_DENYWRITE
)
386 atomic_dec(&inode
->i_writecount
);
387 mutex_lock(&mapping
->i_mmap_mutex
);
388 if (tmp
->vm_flags
& VM_SHARED
)
389 mapping
->i_mmap_writable
++;
390 flush_dcache_mmap_lock(mapping
);
391 /* insert tmp into the share list, just after mpnt */
392 vma_prio_tree_add(tmp
, mpnt
);
393 flush_dcache_mmap_unlock(mapping
);
394 mutex_unlock(&mapping
->i_mmap_mutex
);
398 * Clear hugetlb-related page reserves for children. This only
399 * affects MAP_PRIVATE mappings. Faults generated by the child
400 * are not guaranteed to succeed, even if read-only
402 if (is_vm_hugetlb_page(tmp
))
403 reset_vma_resv_huge_pages(tmp
);
406 * Link in the new vma and copy the page table entries.
409 pprev
= &tmp
->vm_next
;
413 __vma_link_rb(mm
, tmp
, rb_link
, rb_parent
);
414 rb_link
= &tmp
->vm_rb
.rb_right
;
415 rb_parent
= &tmp
->vm_rb
;
418 retval
= copy_page_range(mm
, oldmm
, mpnt
);
420 if (tmp
->vm_ops
&& tmp
->vm_ops
->open
)
421 tmp
->vm_ops
->open(tmp
);
426 /* a new mm has just been created */
427 arch_dup_mmap(oldmm
, mm
);
430 up_write(&mm
->mmap_sem
);
432 up_write(&oldmm
->mmap_sem
);
434 fail_nomem_anon_vma_fork
:
437 kmem_cache_free(vm_area_cachep
, tmp
);
440 vm_unacct_memory(charge
);
444 static inline int mm_alloc_pgd(struct mm_struct
*mm
)
446 mm
->pgd
= pgd_alloc(mm
);
447 if (unlikely(!mm
->pgd
))
452 static inline void mm_free_pgd(struct mm_struct
*mm
)
454 pgd_free(mm
, mm
->pgd
);
457 #define dup_mmap(mm, oldmm) (0)
458 #define mm_alloc_pgd(mm) (0)
459 #define mm_free_pgd(mm)
460 #endif /* CONFIG_MMU */
462 __cacheline_aligned_in_smp
DEFINE_SPINLOCK(mmlist_lock
);
464 #define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
465 #define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
467 static unsigned long default_dump_filter
= MMF_DUMP_FILTER_DEFAULT
;
469 static int __init
coredump_filter_setup(char *s
)
471 default_dump_filter
=
472 (simple_strtoul(s
, NULL
, 0) << MMF_DUMP_FILTER_SHIFT
) &
473 MMF_DUMP_FILTER_MASK
;
477 __setup("coredump_filter=", coredump_filter_setup
);
479 #include <linux/init_task.h>
481 static void mm_init_aio(struct mm_struct
*mm
)
484 spin_lock_init(&mm
->ioctx_lock
);
485 INIT_HLIST_HEAD(&mm
->ioctx_list
);
489 static struct mm_struct
*mm_init(struct mm_struct
*mm
, struct task_struct
*p
)
491 atomic_set(&mm
->mm_users
, 1);
492 atomic_set(&mm
->mm_count
, 1);
493 init_rwsem(&mm
->mmap_sem
);
494 INIT_LIST_HEAD(&mm
->mmlist
);
495 mm
->flags
= (current
->mm
) ?
496 (current
->mm
->flags
& MMF_INIT_MASK
) : default_dump_filter
;
497 mm
->core_state
= NULL
;
499 memset(&mm
->rss_stat
, 0, sizeof(mm
->rss_stat
));
500 spin_lock_init(&mm
->page_table_lock
);
501 mm
->free_area_cache
= TASK_UNMAPPED_BASE
;
502 mm
->cached_hole_size
= ~0UL;
504 mm_init_owner(mm
, p
);
506 if (likely(!mm_alloc_pgd(mm
))) {
508 mmu_notifier_mm_init(mm
);
516 static void check_mm(struct mm_struct
*mm
)
520 for (i
= 0; i
< NR_MM_COUNTERS
; i
++) {
521 long x
= atomic_long_read(&mm
->rss_stat
.count
[i
]);
524 printk(KERN_ALERT
"BUG: Bad rss-counter state "
525 "mm:%p idx:%d val:%ld\n", mm
, i
, x
);
528 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
529 VM_BUG_ON(mm
->pmd_huge_pte
);
534 * Allocate and initialize an mm_struct.
536 struct mm_struct
*mm_alloc(void)
538 struct mm_struct
*mm
;
544 memset(mm
, 0, sizeof(*mm
));
546 return mm_init(mm
, current
);
550 * Called when the last reference to the mm
551 * is dropped: either by a lazy thread or by
552 * mmput. Free the page directory and the mm.
554 void __mmdrop(struct mm_struct
*mm
)
556 BUG_ON(mm
== &init_mm
);
559 mmu_notifier_mm_destroy(mm
);
563 EXPORT_SYMBOL_GPL(__mmdrop
);
566 * Decrement the use count and release all resources for an mm.
568 void mmput(struct mm_struct
*mm
)
572 if (atomic_dec_and_test(&mm
->mm_users
)) {
575 khugepaged_exit(mm
); /* must run before exit_mmap */
577 set_mm_exe_file(mm
, NULL
);
578 if (!list_empty(&mm
->mmlist
)) {
579 spin_lock(&mmlist_lock
);
580 list_del(&mm
->mmlist
);
581 spin_unlock(&mmlist_lock
);
585 module_put(mm
->binfmt
->module
);
589 EXPORT_SYMBOL_GPL(mmput
);
592 * We added or removed a vma mapping the executable. The vmas are only mapped
593 * during exec and are not mapped with the mmap system call.
594 * Callers must hold down_write() on the mm's mmap_sem for these
596 void added_exe_file_vma(struct mm_struct
*mm
)
598 mm
->num_exe_file_vmas
++;
601 void removed_exe_file_vma(struct mm_struct
*mm
)
603 mm
->num_exe_file_vmas
--;
604 if ((mm
->num_exe_file_vmas
== 0) && mm
->exe_file
) {
611 void set_mm_exe_file(struct mm_struct
*mm
, struct file
*new_exe_file
)
614 get_file(new_exe_file
);
617 mm
->exe_file
= new_exe_file
;
618 mm
->num_exe_file_vmas
= 0;
621 struct file
*get_mm_exe_file(struct mm_struct
*mm
)
623 struct file
*exe_file
;
625 /* We need mmap_sem to protect against races with removal of
626 * VM_EXECUTABLE vmas */
627 down_read(&mm
->mmap_sem
);
628 exe_file
= mm
->exe_file
;
631 up_read(&mm
->mmap_sem
);
635 static void dup_mm_exe_file(struct mm_struct
*oldmm
, struct mm_struct
*newmm
)
637 /* It's safe to write the exe_file pointer without exe_file_lock because
638 * this is called during fork when the task is not yet in /proc */
639 newmm
->exe_file
= get_mm_exe_file(oldmm
);
643 * get_task_mm - acquire a reference to the task's mm
645 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
646 * this kernel workthread has transiently adopted a user mm with use_mm,
647 * to do its AIO) is not set and if so returns a reference to it, after
648 * bumping up the use count. User must release the mm via mmput()
649 * after use. Typically used by /proc and ptrace.
651 struct mm_struct
*get_task_mm(struct task_struct
*task
)
653 struct mm_struct
*mm
;
658 if (task
->flags
& PF_KTHREAD
)
661 atomic_inc(&mm
->mm_users
);
666 EXPORT_SYMBOL_GPL(get_task_mm
);
668 struct mm_struct
*mm_access(struct task_struct
*task
, unsigned int mode
)
670 struct mm_struct
*mm
;
673 err
= mutex_lock_killable(&task
->signal
->cred_guard_mutex
);
677 mm
= get_task_mm(task
);
678 if (mm
&& mm
!= current
->mm
&&
679 !ptrace_may_access(task
, mode
)) {
681 mm
= ERR_PTR(-EACCES
);
683 mutex_unlock(&task
->signal
->cred_guard_mutex
);
688 static void complete_vfork_done(struct task_struct
*tsk
)
690 struct completion
*vfork
;
693 vfork
= tsk
->vfork_done
;
695 tsk
->vfork_done
= NULL
;
701 static int wait_for_vfork_done(struct task_struct
*child
,
702 struct completion
*vfork
)
706 freezer_do_not_count();
707 killed
= wait_for_completion_killable(vfork
);
712 child
->vfork_done
= NULL
;
716 put_task_struct(child
);
720 /* Please note the differences between mmput and mm_release.
721 * mmput is called whenever we stop holding onto a mm_struct,
722 * error success whatever.
724 * mm_release is called after a mm_struct has been removed
725 * from the current process.
727 * This difference is important for error handling, when we
728 * only half set up a mm_struct for a new process and need to restore
729 * the old one. Because we mmput the new mm_struct before
730 * restoring the old one. . .
731 * Eric Biederman 10 January 1998
733 void mm_release(struct task_struct
*tsk
, struct mm_struct
*mm
)
735 /* Get rid of any futexes when releasing the mm */
737 if (unlikely(tsk
->robust_list
)) {
738 exit_robust_list(tsk
);
739 tsk
->robust_list
= NULL
;
742 if (unlikely(tsk
->compat_robust_list
)) {
743 compat_exit_robust_list(tsk
);
744 tsk
->compat_robust_list
= NULL
;
747 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
748 exit_pi_state_list(tsk
);
751 /* Get rid of any cached register state */
752 deactivate_mm(tsk
, mm
);
755 complete_vfork_done(tsk
);
758 * If we're exiting normally, clear a user-space tid field if
759 * requested. We leave this alone when dying by signal, to leave
760 * the value intact in a core dump, and to save the unnecessary
761 * trouble, say, a killed vfork parent shouldn't touch this mm.
762 * Userland only wants this done for a sys_exit.
764 if (tsk
->clear_child_tid
) {
765 if (!(tsk
->flags
& PF_SIGNALED
) &&
766 atomic_read(&mm
->mm_users
) > 1) {
768 * We don't check the error code - if userspace has
769 * not set up a proper pointer then tough luck.
771 put_user(0, tsk
->clear_child_tid
);
772 sys_futex(tsk
->clear_child_tid
, FUTEX_WAKE
,
775 tsk
->clear_child_tid
= NULL
;
780 * Allocate a new mm structure and copy contents from the
781 * mm structure of the passed in task structure.
783 struct mm_struct
*dup_mm(struct task_struct
*tsk
)
785 struct mm_struct
*mm
, *oldmm
= current
->mm
;
795 memcpy(mm
, oldmm
, sizeof(*mm
));
798 /* Initializing for Swap token stuff */
799 mm
->token_priority
= 0;
800 mm
->last_interval
= 0;
802 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
803 mm
->pmd_huge_pte
= NULL
;
806 if (!mm_init(mm
, tsk
))
809 if (init_new_context(tsk
, mm
))
812 dup_mm_exe_file(oldmm
, mm
);
814 err
= dup_mmap(mm
, oldmm
);
818 mm
->hiwater_rss
= get_mm_rss(mm
);
819 mm
->hiwater_vm
= mm
->total_vm
;
821 if (mm
->binfmt
&& !try_module_get(mm
->binfmt
->module
))
827 /* don't put binfmt in mmput, we haven't got module yet */
836 * If init_new_context() failed, we cannot use mmput() to free the mm
837 * because it calls destroy_context()
844 static int copy_mm(unsigned long clone_flags
, struct task_struct
*tsk
)
846 struct mm_struct
*mm
, *oldmm
;
849 tsk
->min_flt
= tsk
->maj_flt
= 0;
850 tsk
->nvcsw
= tsk
->nivcsw
= 0;
851 #ifdef CONFIG_DETECT_HUNG_TASK
852 tsk
->last_switch_count
= tsk
->nvcsw
+ tsk
->nivcsw
;
856 tsk
->active_mm
= NULL
;
859 * Are we cloning a kernel thread?
861 * We need to steal a active VM for that..
867 if (clone_flags
& CLONE_VM
) {
868 atomic_inc(&oldmm
->mm_users
);
879 /* Initializing for Swap token stuff */
880 mm
->token_priority
= 0;
881 mm
->last_interval
= 0;
891 static int copy_fs(unsigned long clone_flags
, struct task_struct
*tsk
)
893 struct fs_struct
*fs
= current
->fs
;
894 if (clone_flags
& CLONE_FS
) {
895 /* tsk->fs is already what we want */
896 spin_lock(&fs
->lock
);
898 spin_unlock(&fs
->lock
);
902 spin_unlock(&fs
->lock
);
905 tsk
->fs
= copy_fs_struct(fs
);
911 static int copy_files(unsigned long clone_flags
, struct task_struct
*tsk
)
913 struct files_struct
*oldf
, *newf
;
917 * A background process may not have any files ...
919 oldf
= current
->files
;
923 if (clone_flags
& CLONE_FILES
) {
924 atomic_inc(&oldf
->count
);
928 newf
= dup_fd(oldf
, &error
);
938 static int copy_io(unsigned long clone_flags
, struct task_struct
*tsk
)
941 struct io_context
*ioc
= current
->io_context
;
942 struct io_context
*new_ioc
;
947 * Share io context with parent, if CLONE_IO is set
949 if (clone_flags
& CLONE_IO
) {
950 tsk
->io_context
= ioc_task_link(ioc
);
951 if (unlikely(!tsk
->io_context
))
953 } else if (ioprio_valid(ioc
->ioprio
)) {
954 new_ioc
= get_task_io_context(tsk
, GFP_KERNEL
, NUMA_NO_NODE
);
955 if (unlikely(!new_ioc
))
958 new_ioc
->ioprio
= ioc
->ioprio
;
959 put_io_context(new_ioc
);
965 static int copy_sighand(unsigned long clone_flags
, struct task_struct
*tsk
)
967 struct sighand_struct
*sig
;
969 if (clone_flags
& CLONE_SIGHAND
) {
970 atomic_inc(¤t
->sighand
->count
);
973 sig
= kmem_cache_alloc(sighand_cachep
, GFP_KERNEL
);
974 rcu_assign_pointer(tsk
->sighand
, sig
);
977 atomic_set(&sig
->count
, 1);
978 memcpy(sig
->action
, current
->sighand
->action
, sizeof(sig
->action
));
982 void __cleanup_sighand(struct sighand_struct
*sighand
)
984 if (atomic_dec_and_test(&sighand
->count
)) {
985 signalfd_cleanup(sighand
);
986 kmem_cache_free(sighand_cachep
, sighand
);
992 * Initialize POSIX timer handling for a thread group.
994 static void posix_cpu_timers_init_group(struct signal_struct
*sig
)
996 unsigned long cpu_limit
;
998 /* Thread group counters. */
999 thread_group_cputime_init(sig
);
1001 cpu_limit
= ACCESS_ONCE(sig
->rlim
[RLIMIT_CPU
].rlim_cur
);
1002 if (cpu_limit
!= RLIM_INFINITY
) {
1003 sig
->cputime_expires
.prof_exp
= secs_to_cputime(cpu_limit
);
1004 sig
->cputimer
.running
= 1;
1007 /* The timer lists. */
1008 INIT_LIST_HEAD(&sig
->cpu_timers
[0]);
1009 INIT_LIST_HEAD(&sig
->cpu_timers
[1]);
1010 INIT_LIST_HEAD(&sig
->cpu_timers
[2]);
1013 static int copy_signal(unsigned long clone_flags
, struct task_struct
*tsk
)
1015 struct signal_struct
*sig
;
1017 if (clone_flags
& CLONE_THREAD
)
1020 sig
= kmem_cache_zalloc(signal_cachep
, GFP_KERNEL
);
1025 sig
->nr_threads
= 1;
1026 atomic_set(&sig
->live
, 1);
1027 atomic_set(&sig
->sigcnt
, 1);
1028 init_waitqueue_head(&sig
->wait_chldexit
);
1029 if (clone_flags
& CLONE_NEWPID
)
1030 sig
->flags
|= SIGNAL_UNKILLABLE
;
1031 sig
->curr_target
= tsk
;
1032 init_sigpending(&sig
->shared_pending
);
1033 INIT_LIST_HEAD(&sig
->posix_timers
);
1035 hrtimer_init(&sig
->real_timer
, CLOCK_MONOTONIC
, HRTIMER_MODE_REL
);
1036 sig
->real_timer
.function
= it_real_fn
;
1038 task_lock(current
->group_leader
);
1039 memcpy(sig
->rlim
, current
->signal
->rlim
, sizeof sig
->rlim
);
1040 task_unlock(current
->group_leader
);
1042 posix_cpu_timers_init_group(sig
);
1044 tty_audit_fork(sig
);
1045 sched_autogroup_fork(sig
);
1047 #ifdef CONFIG_CGROUPS
1048 init_rwsem(&sig
->group_rwsem
);
1051 sig
->oom_adj
= current
->signal
->oom_adj
;
1052 sig
->oom_score_adj
= current
->signal
->oom_score_adj
;
1053 sig
->oom_score_adj_min
= current
->signal
->oom_score_adj_min
;
1055 sig
->has_child_subreaper
= current
->signal
->has_child_subreaper
||
1056 current
->signal
->is_child_subreaper
;
1058 mutex_init(&sig
->cred_guard_mutex
);
1063 static void copy_flags(unsigned long clone_flags
, struct task_struct
*p
)
1065 unsigned long new_flags
= p
->flags
;
1067 new_flags
&= ~(PF_SUPERPRIV
| PF_WQ_WORKER
);
1068 new_flags
|= PF_FORKNOEXEC
;
1069 p
->flags
= new_flags
;
1072 SYSCALL_DEFINE1(set_tid_address
, int __user
*, tidptr
)
1074 current
->clear_child_tid
= tidptr
;
1076 return task_pid_vnr(current
);
1079 static void rt_mutex_init_task(struct task_struct
*p
)
1081 raw_spin_lock_init(&p
->pi_lock
);
1082 #ifdef CONFIG_RT_MUTEXES
1083 plist_head_init(&p
->pi_waiters
);
1084 p
->pi_blocked_on
= NULL
;
1088 #ifdef CONFIG_MM_OWNER
1089 void mm_init_owner(struct mm_struct
*mm
, struct task_struct
*p
)
1093 #endif /* CONFIG_MM_OWNER */
1096 * Initialize POSIX timer handling for a single task.
1098 static void posix_cpu_timers_init(struct task_struct
*tsk
)
1100 tsk
->cputime_expires
.prof_exp
= 0;
1101 tsk
->cputime_expires
.virt_exp
= 0;
1102 tsk
->cputime_expires
.sched_exp
= 0;
1103 INIT_LIST_HEAD(&tsk
->cpu_timers
[0]);
1104 INIT_LIST_HEAD(&tsk
->cpu_timers
[1]);
1105 INIT_LIST_HEAD(&tsk
->cpu_timers
[2]);
1109 * This creates a new process as a copy of the old one,
1110 * but does not actually start it yet.
1112 * It copies the registers, and all the appropriate
1113 * parts of the process environment (as per the clone
1114 * flags). The actual kick-off is left to the caller.
1116 static struct task_struct
*copy_process(unsigned long clone_flags
,
1117 unsigned long stack_start
,
1118 struct pt_regs
*regs
,
1119 unsigned long stack_size
,
1120 int __user
*child_tidptr
,
1125 struct task_struct
*p
;
1126 int cgroup_callbacks_done
= 0;
1128 if ((clone_flags
& (CLONE_NEWNS
|CLONE_FS
)) == (CLONE_NEWNS
|CLONE_FS
))
1129 return ERR_PTR(-EINVAL
);
1132 * Thread groups must share signals as well, and detached threads
1133 * can only be started up within the thread group.
1135 if ((clone_flags
& CLONE_THREAD
) && !(clone_flags
& CLONE_SIGHAND
))
1136 return ERR_PTR(-EINVAL
);
1139 * Shared signal handlers imply shared VM. By way of the above,
1140 * thread groups also imply shared VM. Blocking this case allows
1141 * for various simplifications in other code.
1143 if ((clone_flags
& CLONE_SIGHAND
) && !(clone_flags
& CLONE_VM
))
1144 return ERR_PTR(-EINVAL
);
1147 * Siblings of global init remain as zombies on exit since they are
1148 * not reaped by their parent (swapper). To solve this and to avoid
1149 * multi-rooted process trees, prevent global and container-inits
1150 * from creating siblings.
1152 if ((clone_flags
& CLONE_PARENT
) &&
1153 current
->signal
->flags
& SIGNAL_UNKILLABLE
)
1154 return ERR_PTR(-EINVAL
);
1156 retval
= security_task_create(clone_flags
);
1161 p
= dup_task_struct(current
);
1165 ftrace_graph_init_task(p
);
1167 rt_mutex_init_task(p
);
1169 #ifdef CONFIG_PROVE_LOCKING
1170 DEBUG_LOCKS_WARN_ON(!p
->hardirqs_enabled
);
1171 DEBUG_LOCKS_WARN_ON(!p
->softirqs_enabled
);
1174 if (atomic_read(&p
->real_cred
->user
->processes
) >=
1175 task_rlimit(p
, RLIMIT_NPROC
)) {
1176 if (!capable(CAP_SYS_ADMIN
) && !capable(CAP_SYS_RESOURCE
) &&
1177 p
->real_cred
->user
!= INIT_USER
)
1180 current
->flags
&= ~PF_NPROC_EXCEEDED
;
1182 retval
= copy_creds(p
, clone_flags
);
1187 * If multiple threads are within copy_process(), then this check
1188 * triggers too late. This doesn't hurt, the check is only there
1189 * to stop root fork bombs.
1192 if (nr_threads
>= max_threads
)
1193 goto bad_fork_cleanup_count
;
1195 if (!try_module_get(task_thread_info(p
)->exec_domain
->module
))
1196 goto bad_fork_cleanup_count
;
1199 delayacct_tsk_init(p
); /* Must remain after dup_task_struct() */
1200 copy_flags(clone_flags
, p
);
1201 INIT_LIST_HEAD(&p
->children
);
1202 INIT_LIST_HEAD(&p
->sibling
);
1203 rcu_copy_process(p
);
1204 p
->vfork_done
= NULL
;
1205 spin_lock_init(&p
->alloc_lock
);
1207 init_sigpending(&p
->pending
);
1209 p
->utime
= p
->stime
= p
->gtime
= 0;
1210 p
->utimescaled
= p
->stimescaled
= 0;
1211 #ifndef CONFIG_VIRT_CPU_ACCOUNTING
1212 p
->prev_utime
= p
->prev_stime
= 0;
1214 #if defined(SPLIT_RSS_COUNTING)
1215 memset(&p
->rss_stat
, 0, sizeof(p
->rss_stat
));
1218 p
->default_timer_slack_ns
= current
->timer_slack_ns
;
1220 task_io_accounting_init(&p
->ioac
);
1221 acct_clear_integrals(p
);
1223 posix_cpu_timers_init(p
);
1225 do_posix_clock_monotonic_gettime(&p
->start_time
);
1226 p
->real_start_time
= p
->start_time
;
1227 monotonic_to_bootbased(&p
->real_start_time
);
1228 p
->io_context
= NULL
;
1229 p
->audit_context
= NULL
;
1230 if (clone_flags
& CLONE_THREAD
)
1231 threadgroup_change_begin(current
);
1234 p
->mempolicy
= mpol_dup(p
->mempolicy
);
1235 if (IS_ERR(p
->mempolicy
)) {
1236 retval
= PTR_ERR(p
->mempolicy
);
1237 p
->mempolicy
= NULL
;
1238 goto bad_fork_cleanup_cgroup
;
1240 mpol_fix_fork_child_flag(p
);
1242 #ifdef CONFIG_CPUSETS
1243 p
->cpuset_mem_spread_rotor
= NUMA_NO_NODE
;
1244 p
->cpuset_slab_spread_rotor
= NUMA_NO_NODE
;
1245 seqcount_init(&p
->mems_allowed_seq
);
1247 #ifdef CONFIG_TRACE_IRQFLAGS
1249 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
1250 p
->hardirqs_enabled
= 1;
1252 p
->hardirqs_enabled
= 0;
1254 p
->hardirq_enable_ip
= 0;
1255 p
->hardirq_enable_event
= 0;
1256 p
->hardirq_disable_ip
= _THIS_IP_
;
1257 p
->hardirq_disable_event
= 0;
1258 p
->softirqs_enabled
= 1;
1259 p
->softirq_enable_ip
= _THIS_IP_
;
1260 p
->softirq_enable_event
= 0;
1261 p
->softirq_disable_ip
= 0;
1262 p
->softirq_disable_event
= 0;
1263 p
->hardirq_context
= 0;
1264 p
->softirq_context
= 0;
1266 #ifdef CONFIG_LOCKDEP
1267 p
->lockdep_depth
= 0; /* no locks held yet */
1268 p
->curr_chain_key
= 0;
1269 p
->lockdep_recursion
= 0;
1272 #ifdef CONFIG_DEBUG_MUTEXES
1273 p
->blocked_on
= NULL
; /* not blocked yet */
1275 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
1276 p
->memcg_batch
.do_batch
= 0;
1277 p
->memcg_batch
.memcg
= NULL
;
1280 /* Perform scheduler related setup. Assign this task to a CPU. */
1283 retval
= perf_event_init_task(p
);
1285 goto bad_fork_cleanup_policy
;
1286 retval
= audit_alloc(p
);
1288 goto bad_fork_cleanup_policy
;
1289 /* copy all the process information */
1290 retval
= copy_semundo(clone_flags
, p
);
1292 goto bad_fork_cleanup_audit
;
1293 retval
= copy_files(clone_flags
, p
);
1295 goto bad_fork_cleanup_semundo
;
1296 retval
= copy_fs(clone_flags
, p
);
1298 goto bad_fork_cleanup_files
;
1299 retval
= copy_sighand(clone_flags
, p
);
1301 goto bad_fork_cleanup_fs
;
1302 retval
= copy_signal(clone_flags
, p
);
1304 goto bad_fork_cleanup_sighand
;
1305 retval
= copy_mm(clone_flags
, p
);
1307 goto bad_fork_cleanup_signal
;
1308 retval
= copy_namespaces(clone_flags
, p
);
1310 goto bad_fork_cleanup_mm
;
1311 retval
= copy_io(clone_flags
, p
);
1313 goto bad_fork_cleanup_namespaces
;
1314 retval
= copy_thread(clone_flags
, stack_start
, stack_size
, p
, regs
);
1316 goto bad_fork_cleanup_io
;
1318 if (pid
!= &init_struct_pid
) {
1320 pid
= alloc_pid(p
->nsproxy
->pid_ns
);
1322 goto bad_fork_cleanup_io
;
1325 p
->pid
= pid_nr(pid
);
1327 if (clone_flags
& CLONE_THREAD
)
1328 p
->tgid
= current
->tgid
;
1330 p
->set_child_tid
= (clone_flags
& CLONE_CHILD_SETTID
) ? child_tidptr
: NULL
;
1332 * Clear TID on mm_release()?
1334 p
->clear_child_tid
= (clone_flags
& CLONE_CHILD_CLEARTID
) ? child_tidptr
: NULL
;
1339 p
->robust_list
= NULL
;
1340 #ifdef CONFIG_COMPAT
1341 p
->compat_robust_list
= NULL
;
1343 INIT_LIST_HEAD(&p
->pi_state_list
);
1344 p
->pi_state_cache
= NULL
;
1347 * sigaltstack should be cleared when sharing the same VM
1349 if ((clone_flags
& (CLONE_VM
|CLONE_VFORK
)) == CLONE_VM
)
1350 p
->sas_ss_sp
= p
->sas_ss_size
= 0;
1353 * Syscall tracing and stepping should be turned off in the
1354 * child regardless of CLONE_PTRACE.
1356 user_disable_single_step(p
);
1357 clear_tsk_thread_flag(p
, TIF_SYSCALL_TRACE
);
1358 #ifdef TIF_SYSCALL_EMU
1359 clear_tsk_thread_flag(p
, TIF_SYSCALL_EMU
);
1361 clear_all_latency_tracing(p
);
1363 /* ok, now we should be set up.. */
1364 if (clone_flags
& CLONE_THREAD
)
1365 p
->exit_signal
= -1;
1366 else if (clone_flags
& CLONE_PARENT
)
1367 p
->exit_signal
= current
->group_leader
->exit_signal
;
1369 p
->exit_signal
= (clone_flags
& CSIGNAL
);
1371 p
->pdeath_signal
= 0;
1375 p
->nr_dirtied_pause
= 128 >> (PAGE_SHIFT
- 10);
1376 p
->dirty_paused_when
= 0;
1379 * Ok, make it visible to the rest of the system.
1380 * We dont wake it up yet.
1382 p
->group_leader
= p
;
1383 INIT_LIST_HEAD(&p
->thread_group
);
1385 /* Now that the task is set up, run cgroup callbacks if
1386 * necessary. We need to run them before the task is visible
1387 * on the tasklist. */
1388 cgroup_fork_callbacks(p
);
1389 cgroup_callbacks_done
= 1;
1391 /* Need tasklist lock for parent etc handling! */
1392 write_lock_irq(&tasklist_lock
);
1394 /* CLONE_PARENT re-uses the old parent */
1395 if (clone_flags
& (CLONE_PARENT
|CLONE_THREAD
)) {
1396 p
->real_parent
= current
->real_parent
;
1397 p
->parent_exec_id
= current
->parent_exec_id
;
1399 p
->real_parent
= current
;
1400 p
->parent_exec_id
= current
->self_exec_id
;
1403 spin_lock(¤t
->sighand
->siglock
);
1406 * Process group and session signals need to be delivered to just the
1407 * parent before the fork or both the parent and the child after the
1408 * fork. Restart if a signal comes in before we add the new process to
1409 * it's process group.
1410 * A fatal signal pending means that current will exit, so the new
1411 * thread can't slip out of an OOM kill (or normal SIGKILL).
1413 recalc_sigpending();
1414 if (signal_pending(current
)) {
1415 spin_unlock(¤t
->sighand
->siglock
);
1416 write_unlock_irq(&tasklist_lock
);
1417 retval
= -ERESTARTNOINTR
;
1418 goto bad_fork_free_pid
;
1421 if (clone_flags
& CLONE_THREAD
) {
1422 current
->signal
->nr_threads
++;
1423 atomic_inc(¤t
->signal
->live
);
1424 atomic_inc(¤t
->signal
->sigcnt
);
1425 p
->group_leader
= current
->group_leader
;
1426 list_add_tail_rcu(&p
->thread_group
, &p
->group_leader
->thread_group
);
1429 if (likely(p
->pid
)) {
1430 ptrace_init_task(p
, (clone_flags
& CLONE_PTRACE
) || trace
);
1432 if (thread_group_leader(p
)) {
1433 if (is_child_reaper(pid
))
1434 p
->nsproxy
->pid_ns
->child_reaper
= p
;
1436 p
->signal
->leader_pid
= pid
;
1437 p
->signal
->tty
= tty_kref_get(current
->signal
->tty
);
1438 attach_pid(p
, PIDTYPE_PGID
, task_pgrp(current
));
1439 attach_pid(p
, PIDTYPE_SID
, task_session(current
));
1440 list_add_tail(&p
->sibling
, &p
->real_parent
->children
);
1441 list_add_tail_rcu(&p
->tasks
, &init_task
.tasks
);
1442 __this_cpu_inc(process_counts
);
1444 attach_pid(p
, PIDTYPE_PID
, pid
);
1449 spin_unlock(¤t
->sighand
->siglock
);
1450 write_unlock_irq(&tasklist_lock
);
1451 proc_fork_connector(p
);
1452 cgroup_post_fork(p
);
1453 if (clone_flags
& CLONE_THREAD
)
1454 threadgroup_change_end(current
);
1457 trace_task_newtask(p
, clone_flags
);
1462 if (pid
!= &init_struct_pid
)
1464 bad_fork_cleanup_io
:
1467 bad_fork_cleanup_namespaces
:
1468 if (unlikely(clone_flags
& CLONE_NEWPID
))
1469 pid_ns_release_proc(p
->nsproxy
->pid_ns
);
1470 exit_task_namespaces(p
);
1471 bad_fork_cleanup_mm
:
1474 bad_fork_cleanup_signal
:
1475 if (!(clone_flags
& CLONE_THREAD
))
1476 free_signal_struct(p
->signal
);
1477 bad_fork_cleanup_sighand
:
1478 __cleanup_sighand(p
->sighand
);
1479 bad_fork_cleanup_fs
:
1480 exit_fs(p
); /* blocking */
1481 bad_fork_cleanup_files
:
1482 exit_files(p
); /* blocking */
1483 bad_fork_cleanup_semundo
:
1485 bad_fork_cleanup_audit
:
1487 bad_fork_cleanup_policy
:
1488 perf_event_free_task(p
);
1490 mpol_put(p
->mempolicy
);
1491 bad_fork_cleanup_cgroup
:
1493 if (clone_flags
& CLONE_THREAD
)
1494 threadgroup_change_end(current
);
1495 cgroup_exit(p
, cgroup_callbacks_done
);
1496 delayacct_tsk_free(p
);
1497 module_put(task_thread_info(p
)->exec_domain
->module
);
1498 bad_fork_cleanup_count
:
1499 atomic_dec(&p
->cred
->user
->processes
);
1504 return ERR_PTR(retval
);
1507 noinline
struct pt_regs
* __cpuinit
__attribute__((weak
)) idle_regs(struct pt_regs
*regs
)
1509 memset(regs
, 0, sizeof(struct pt_regs
));
1513 static inline void init_idle_pids(struct pid_link
*links
)
1517 for (type
= PIDTYPE_PID
; type
< PIDTYPE_MAX
; ++type
) {
1518 INIT_HLIST_NODE(&links
[type
].node
); /* not really needed */
1519 links
[type
].pid
= &init_struct_pid
;
1523 struct task_struct
* __cpuinit
fork_idle(int cpu
)
1525 struct task_struct
*task
;
1526 struct pt_regs regs
;
1528 task
= copy_process(CLONE_VM
, 0, idle_regs(®s
), 0, NULL
,
1529 &init_struct_pid
, 0);
1530 if (!IS_ERR(task
)) {
1531 init_idle_pids(task
->pids
);
1532 init_idle(task
, cpu
);
1539 * Ok, this is the main fork-routine.
1541 * It copies the process, and if successful kick-starts
1542 * it and waits for it to finish using the VM if required.
1544 long do_fork(unsigned long clone_flags
,
1545 unsigned long stack_start
,
1546 struct pt_regs
*regs
,
1547 unsigned long stack_size
,
1548 int __user
*parent_tidptr
,
1549 int __user
*child_tidptr
)
1551 struct task_struct
*p
;
1556 * Do some preliminary argument and permissions checking before we
1557 * actually start allocating stuff
1559 if (clone_flags
& CLONE_NEWUSER
) {
1560 if (clone_flags
& CLONE_THREAD
)
1562 /* hopefully this check will go away when userns support is
1565 if (!capable(CAP_SYS_ADMIN
) || !capable(CAP_SETUID
) ||
1566 !capable(CAP_SETGID
))
1571 * Determine whether and which event to report to ptracer. When
1572 * called from kernel_thread or CLONE_UNTRACED is explicitly
1573 * requested, no event is reported; otherwise, report if the event
1574 * for the type of forking is enabled.
1576 if (likely(user_mode(regs
)) && !(clone_flags
& CLONE_UNTRACED
)) {
1577 if (clone_flags
& CLONE_VFORK
)
1578 trace
= PTRACE_EVENT_VFORK
;
1579 else if ((clone_flags
& CSIGNAL
) != SIGCHLD
)
1580 trace
= PTRACE_EVENT_CLONE
;
1582 trace
= PTRACE_EVENT_FORK
;
1584 if (likely(!ptrace_event_enabled(current
, trace
)))
1588 p
= copy_process(clone_flags
, stack_start
, regs
, stack_size
,
1589 child_tidptr
, NULL
, trace
);
1591 * Do this prior waking up the new thread - the thread pointer
1592 * might get invalid after that point, if the thread exits quickly.
1595 struct completion vfork
;
1597 trace_sched_process_fork(current
, p
);
1599 nr
= task_pid_vnr(p
);
1601 if (clone_flags
& CLONE_PARENT_SETTID
)
1602 put_user(nr
, parent_tidptr
);
1604 if (clone_flags
& CLONE_VFORK
) {
1605 p
->vfork_done
= &vfork
;
1606 init_completion(&vfork
);
1610 wake_up_new_task(p
);
1612 /* forking complete and child started to run, tell ptracer */
1613 if (unlikely(trace
))
1614 ptrace_event(trace
, nr
);
1616 if (clone_flags
& CLONE_VFORK
) {
1617 if (!wait_for_vfork_done(p
, &vfork
))
1618 ptrace_event(PTRACE_EVENT_VFORK_DONE
, nr
);
1626 #ifndef ARCH_MIN_MMSTRUCT_ALIGN
1627 #define ARCH_MIN_MMSTRUCT_ALIGN 0
1630 static void sighand_ctor(void *data
)
1632 struct sighand_struct
*sighand
= data
;
1634 spin_lock_init(&sighand
->siglock
);
1635 init_waitqueue_head(&sighand
->signalfd_wqh
);
1638 void __init
proc_caches_init(void)
1640 sighand_cachep
= kmem_cache_create("sighand_cache",
1641 sizeof(struct sighand_struct
), 0,
1642 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_DESTROY_BY_RCU
|
1643 SLAB_NOTRACK
, sighand_ctor
);
1644 signal_cachep
= kmem_cache_create("signal_cache",
1645 sizeof(struct signal_struct
), 0,
1646 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1647 files_cachep
= kmem_cache_create("files_cache",
1648 sizeof(struct files_struct
), 0,
1649 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1650 fs_cachep
= kmem_cache_create("fs_cache",
1651 sizeof(struct fs_struct
), 0,
1652 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1654 * FIXME! The "sizeof(struct mm_struct)" currently includes the
1655 * whole struct cpumask for the OFFSTACK case. We could change
1656 * this to *only* allocate as much of it as required by the
1657 * maximum number of CPU's we can ever have. The cpumask_allocation
1658 * is at the end of the structure, exactly for that reason.
1660 mm_cachep
= kmem_cache_create("mm_struct",
1661 sizeof(struct mm_struct
), ARCH_MIN_MMSTRUCT_ALIGN
,
1662 SLAB_HWCACHE_ALIGN
|SLAB_PANIC
|SLAB_NOTRACK
, NULL
);
1663 vm_area_cachep
= KMEM_CACHE(vm_area_struct
, SLAB_PANIC
);
1665 nsproxy_cache_init();
1669 * Check constraints on flags passed to the unshare system call.
1671 static int check_unshare_flags(unsigned long unshare_flags
)
1673 if (unshare_flags
& ~(CLONE_THREAD
|CLONE_FS
|CLONE_NEWNS
|CLONE_SIGHAND
|
1674 CLONE_VM
|CLONE_FILES
|CLONE_SYSVSEM
|
1675 CLONE_NEWUTS
|CLONE_NEWIPC
|CLONE_NEWNET
))
1678 * Not implemented, but pretend it works if there is nothing to
1679 * unshare. Note that unsharing CLONE_THREAD or CLONE_SIGHAND
1680 * needs to unshare vm.
1682 if (unshare_flags
& (CLONE_THREAD
| CLONE_SIGHAND
| CLONE_VM
)) {
1683 /* FIXME: get_task_mm() increments ->mm_users */
1684 if (atomic_read(¤t
->mm
->mm_users
) > 1)
1692 * Unshare the filesystem structure if it is being shared
1694 static int unshare_fs(unsigned long unshare_flags
, struct fs_struct
**new_fsp
)
1696 struct fs_struct
*fs
= current
->fs
;
1698 if (!(unshare_flags
& CLONE_FS
) || !fs
)
1701 /* don't need lock here; in the worst case we'll do useless copy */
1705 *new_fsp
= copy_fs_struct(fs
);
1713 * Unshare file descriptor table if it is being shared
1715 static int unshare_fd(unsigned long unshare_flags
, struct files_struct
**new_fdp
)
1717 struct files_struct
*fd
= current
->files
;
1720 if ((unshare_flags
& CLONE_FILES
) &&
1721 (fd
&& atomic_read(&fd
->count
) > 1)) {
1722 *new_fdp
= dup_fd(fd
, &error
);
1731 * unshare allows a process to 'unshare' part of the process
1732 * context which was originally shared using clone. copy_*
1733 * functions used by do_fork() cannot be used here directly
1734 * because they modify an inactive task_struct that is being
1735 * constructed. Here we are modifying the current, active,
1738 SYSCALL_DEFINE1(unshare
, unsigned long, unshare_flags
)
1740 struct fs_struct
*fs
, *new_fs
= NULL
;
1741 struct files_struct
*fd
, *new_fd
= NULL
;
1742 struct nsproxy
*new_nsproxy
= NULL
;
1746 err
= check_unshare_flags(unshare_flags
);
1748 goto bad_unshare_out
;
1751 * If unsharing namespace, must also unshare filesystem information.
1753 if (unshare_flags
& CLONE_NEWNS
)
1754 unshare_flags
|= CLONE_FS
;
1756 * CLONE_NEWIPC must also detach from the undolist: after switching
1757 * to a new ipc namespace, the semaphore arrays from the old
1758 * namespace are unreachable.
1760 if (unshare_flags
& (CLONE_NEWIPC
|CLONE_SYSVSEM
))
1762 err
= unshare_fs(unshare_flags
, &new_fs
);
1764 goto bad_unshare_out
;
1765 err
= unshare_fd(unshare_flags
, &new_fd
);
1767 goto bad_unshare_cleanup_fs
;
1768 err
= unshare_nsproxy_namespaces(unshare_flags
, &new_nsproxy
, new_fs
);
1770 goto bad_unshare_cleanup_fd
;
1772 if (new_fs
|| new_fd
|| do_sysvsem
|| new_nsproxy
) {
1775 * CLONE_SYSVSEM is equivalent to sys_exit().
1781 switch_task_namespaces(current
, new_nsproxy
);
1789 spin_lock(&fs
->lock
);
1790 current
->fs
= new_fs
;
1795 spin_unlock(&fs
->lock
);
1799 fd
= current
->files
;
1800 current
->files
= new_fd
;
1804 task_unlock(current
);
1808 put_nsproxy(new_nsproxy
);
1810 bad_unshare_cleanup_fd
:
1812 put_files_struct(new_fd
);
1814 bad_unshare_cleanup_fs
:
1816 free_fs_struct(new_fs
);
1823 * Helper to unshare the files of the current task.
1824 * We don't want to expose copy_files internals to
1825 * the exec layer of the kernel.
1828 int unshare_files(struct files_struct
**displaced
)
1830 struct task_struct
*task
= current
;
1831 struct files_struct
*copy
= NULL
;
1834 error
= unshare_fd(CLONE_FILES
, ©
);
1835 if (error
|| !copy
) {
1839 *displaced
= task
->files
;