projects/linux·blob v6.9-rc4 · refs

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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/fork.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8/*
9 * 'fork.c' contains the help-routines for the 'fork' system call
10 * (see also entry.S and others).
11 * Fork is rather simple, once you get the hang of it, but the memory
12 * management can be a bitch. See 'mm/memory.c': 'copy_page_range()'
13 */
14
15#include <linux/anon_inodes.h>
16#include <linux/slab.h>
17#include <linux/sched/autogroup.h>
18#include <linux/sched/mm.h>
19#include <linux/sched/coredump.h>
20#include <linux/sched/user.h>
21#include <linux/sched/numa_balancing.h>
22#include <linux/sched/stat.h>
23#include <linux/sched/task.h>
24#include <linux/sched/task_stack.h>
25#include <linux/sched/cputime.h>
26#include <linux/seq_file.h>
27#include <linux/rtmutex.h>
28#include <linux/init.h>
29#include <linux/unistd.h>
30#include <linux/module.h>
31#include <linux/vmalloc.h>
32#include <linux/completion.h>
33#include <linux/personality.h>
34#include <linux/mempolicy.h>
35#include <linux/sem.h>
36#include <linux/file.h>
37#include <linux/fdtable.h>
38#include <linux/iocontext.h>
39#include <linux/key.h>
40#include <linux/kmsan.h>
41#include <linux/binfmts.h>
42#include <linux/mman.h>
43#include <linux/mmu_notifier.h>
44#include <linux/fs.h>
45#include <linux/mm.h>
46#include <linux/mm_inline.h>
47#include <linux/nsproxy.h>
48#include <linux/capability.h>
49#include <linux/cpu.h>
50#include <linux/cgroup.h>
51#include <linux/security.h>
52#include <linux/hugetlb.h>
53#include <linux/seccomp.h>
54#include <linux/swap.h>
55#include <linux/syscalls.h>
56#include <linux/syscall_user_dispatch.h>
57#include <linux/jiffies.h>
58#include <linux/futex.h>
59#include <linux/compat.h>
60#include <linux/kthread.h>
61#include <linux/task_io_accounting_ops.h>
62#include <linux/rcupdate.h>
63#include <linux/ptrace.h>
64#include <linux/mount.h>
65#include <linux/audit.h>
66#include <linux/memcontrol.h>
67#include <linux/ftrace.h>
68#include <linux/proc_fs.h>
69#include <linux/profile.h>
70#include <linux/rmap.h>
71#include <linux/ksm.h>
72#include <linux/acct.h>
73#include <linux/userfaultfd_k.h>
74#include <linux/tsacct_kern.h>
75#include <linux/cn_proc.h>
76#include <linux/freezer.h>
77#include <linux/delayacct.h>
78#include <linux/taskstats_kern.h>
79#include <linux/tty.h>
80#include <linux/fs_struct.h>
81#include <linux/magic.h>
82#include <linux/perf_event.h>
83#include <linux/posix-timers.h>
84#include <linux/user-return-notifier.h>
85#include <linux/oom.h>
86#include <linux/khugepaged.h>
87#include <linux/signalfd.h>
88#include <linux/uprobes.h>
89#include <linux/aio.h>
90#include <linux/compiler.h>
91#include <linux/sysctl.h>
92#include <linux/kcov.h>
93#include <linux/livepatch.h>
94#include <linux/thread_info.h>
95#include <linux/stackleak.h>
96#include <linux/kasan.h>
97#include <linux/scs.h>
98#include <linux/io_uring.h>
99#include <linux/bpf.h>
100#include <linux/stackprotector.h>
101#include <linux/user_events.h>
102#include <linux/iommu.h>
103#include <linux/rseq.h>
104#include <uapi/linux/pidfd.h>
105#include <linux/pidfs.h>
106
107#include <asm/pgalloc.h>
108#include <linux/uaccess.h>
109#include <asm/mmu_context.h>
110#include <asm/cacheflush.h>
111#include <asm/tlbflush.h>
112
113#include <trace/events/sched.h>
114
115#define CREATE_TRACE_POINTS
116#include <trace/events/task.h>
117
118/*
119 * Minimum number of threads to boot the kernel
120 */
121#define MIN_THREADS 20
122
123/*
124 * Maximum number of threads
125 */
126#define MAX_THREADS FUTEX_TID_MASK
127
128/*
129 * Protected counters by write_lock_irq(&tasklist_lock)
130 */
131unsigned long total_forks; /* Handle normal Linux uptimes. */
132int nr_threads; /* The idle threads do not count.. */
133
134static int max_threads; /* tunable limit on nr_threads */
135
136#define NAMED_ARRAY_INDEX(x) [x] = __stringify(x)
137
138static const char * const resident_page_types[] = {
139 NAMED_ARRAY_INDEX(MM_FILEPAGES),
140 NAMED_ARRAY_INDEX(MM_ANONPAGES),
141 NAMED_ARRAY_INDEX(MM_SWAPENTS),
142 NAMED_ARRAY_INDEX(MM_SHMEMPAGES),
143};
144
145DEFINE_PER_CPU(unsigned long, process_counts) = 0;
146
147__cacheline_aligned DEFINE_RWLOCK(tasklist_lock); /* outer */
148
149#ifdef CONFIG_PROVE_RCU
150int lockdep_tasklist_lock_is_held(void)
151{
152 return lockdep_is_held(&tasklist_lock);
153}
154EXPORT_SYMBOL_GPL(lockdep_tasklist_lock_is_held);
155#endif /* #ifdef CONFIG_PROVE_RCU */
156
157int nr_processes(void)
158{
159 int cpu;
160 int total = 0;
161
162 for_each_possible_cpu(cpu)
163 total += per_cpu(process_counts, cpu);
164
165 return total;
166}
167
168void __weak arch_release_task_struct(struct task_struct *tsk)
169{
170}
171
172static struct kmem_cache *task_struct_cachep;
173
174static inline struct task_struct *alloc_task_struct_node(int node)
175{
176 return kmem_cache_alloc_node(task_struct_cachep, GFP_KERNEL, node);
177}
178
179static inline void free_task_struct(struct task_struct *tsk)
180{
181 kmem_cache_free(task_struct_cachep, tsk);
182}
183
184/*
185 * Allocate pages if THREAD_SIZE is >= PAGE_SIZE, otherwise use a
186 * kmemcache based allocator.
187 */
188# if THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)
189
190# ifdef CONFIG_VMAP_STACK
191/*
192 * vmalloc() is a bit slow, and calling vfree() enough times will force a TLB
193 * flush. Try to minimize the number of calls by caching stacks.
194 */
195#define NR_CACHED_STACKS 2
196static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]);
197
198struct vm_stack {
199 struct rcu_head rcu;
200 struct vm_struct *stack_vm_area;
201};
202
203static bool try_release_thread_stack_to_cache(struct vm_struct *vm)
204{
205 unsigned int i;
206
207 for (i = 0; i < NR_CACHED_STACKS; i++) {
208 if (this_cpu_cmpxchg(cached_stacks[i], NULL, vm) != NULL)
209 continue;
210 return true;
211 }
212 return false;
213}
214
215static void thread_stack_free_rcu(struct rcu_head *rh)
216{
217 struct vm_stack *vm_stack = container_of(rh, struct vm_stack, rcu);
218
219 if (try_release_thread_stack_to_cache(vm_stack->stack_vm_area))
220 return;
221
222 vfree(vm_stack);
223}
224
225static void thread_stack_delayed_free(struct task_struct *tsk)
226{
227 struct vm_stack *vm_stack = tsk->stack;
228
229 vm_stack->stack_vm_area = tsk->stack_vm_area;
230 call_rcu(&vm_stack->rcu, thread_stack_free_rcu);
231}
232
233static int free_vm_stack_cache(unsigned int cpu)
234{
235 struct vm_struct **cached_vm_stacks = per_cpu_ptr(cached_stacks, cpu);
236 int i;
237
238 for (i = 0; i < NR_CACHED_STACKS; i++) {
239 struct vm_struct *vm_stack = cached_vm_stacks[i];
240
241 if (!vm_stack)
242 continue;
243
244 vfree(vm_stack->addr);
245 cached_vm_stacks[i] = NULL;
246 }
247
248 return 0;
249}
250
251static int memcg_charge_kernel_stack(struct vm_struct *vm)
252{
253 int i;
254 int ret;
255 int nr_charged = 0;
256
257 BUG_ON(vm->nr_pages != THREAD_SIZE / PAGE_SIZE);
258
259 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++) {
260 ret = memcg_kmem_charge_page(vm->pages[i], GFP_KERNEL, 0);
261 if (ret)
262 goto err;
263 nr_charged++;
264 }
265 return 0;
266err:
267 for (i = 0; i < nr_charged; i++)
268 memcg_kmem_uncharge_page(vm->pages[i], 0);
269 return ret;
270}
271
272static int alloc_thread_stack_node(struct task_struct *tsk, int node)
273{
274 struct vm_struct *vm;
275 void *stack;
276 int i;
277
278 for (i = 0; i < NR_CACHED_STACKS; i++) {
279 struct vm_struct *s;
280
281 s = this_cpu_xchg(cached_stacks[i], NULL);
282
283 if (!s)
284 continue;
285
286 /* Reset stack metadata. */
287 kasan_unpoison_range(s->addr, THREAD_SIZE);
288
289 stack = kasan_reset_tag(s->addr);
290
291 /* Clear stale pointers from reused stack. */
292 memset(stack, 0, THREAD_SIZE);
293
294 if (memcg_charge_kernel_stack(s)) {
295 vfree(s->addr);
296 return -ENOMEM;
297 }
298
299 tsk->stack_vm_area = s;
300 tsk->stack = stack;
301 return 0;
302 }
303
304 /*
305 * Allocated stacks are cached and later reused by new threads,
306 * so memcg accounting is performed manually on assigning/releasing
307 * stacks to tasks. Drop __GFP_ACCOUNT.
308 */
309 stack = __vmalloc_node_range(THREAD_SIZE, THREAD_ALIGN,
310 VMALLOC_START, VMALLOC_END,
311 THREADINFO_GFP & ~__GFP_ACCOUNT,
312 PAGE_KERNEL,
313 0, node, __builtin_return_address(0));
314 if (!stack)
315 return -ENOMEM;
316
317 vm = find_vm_area(stack);
318 if (memcg_charge_kernel_stack(vm)) {
319 vfree(stack);
320 return -ENOMEM;
321 }
322 /*
323 * We can't call find_vm_area() in interrupt context, and
324 * free_thread_stack() can be called in interrupt context,
325 * so cache the vm_struct.
326 */
327 tsk->stack_vm_area = vm;
328 stack = kasan_reset_tag(stack);
329 tsk->stack = stack;
330 return 0;
331}
332
333static void free_thread_stack(struct task_struct *tsk)
334{
335 if (!try_release_thread_stack_to_cache(tsk->stack_vm_area))
336 thread_stack_delayed_free(tsk);
337
338 tsk->stack = NULL;
339 tsk->stack_vm_area = NULL;
340}
341
342# else /* !CONFIG_VMAP_STACK */
343
344static void thread_stack_free_rcu(struct rcu_head *rh)
345{
346 __free_pages(virt_to_page(rh), THREAD_SIZE_ORDER);
347}
348
349static void thread_stack_delayed_free(struct task_struct *tsk)
350{
351 struct rcu_head *rh = tsk->stack;
352
353 call_rcu(rh, thread_stack_free_rcu);
354}
355
356static int alloc_thread_stack_node(struct task_struct *tsk, int node)
357{
358 struct page *page = alloc_pages_node(node, THREADINFO_GFP,
359 THREAD_SIZE_ORDER);
360
361 if (likely(page)) {
362 tsk->stack = kasan_reset_tag(page_address(page));
363 return 0;
364 }
365 return -ENOMEM;
366}
367
368static void free_thread_stack(struct task_struct *tsk)
369{
370 thread_stack_delayed_free(tsk);
371 tsk->stack = NULL;
372}
373
374# endif /* CONFIG_VMAP_STACK */
375# else /* !(THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK)) */
376
377static struct kmem_cache *thread_stack_cache;
378
379static void thread_stack_free_rcu(struct rcu_head *rh)
380{
381 kmem_cache_free(thread_stack_cache, rh);
382}
383
384static void thread_stack_delayed_free(struct task_struct *tsk)
385{
386 struct rcu_head *rh = tsk->stack;
387
388 call_rcu(rh, thread_stack_free_rcu);
389}
390
391static int alloc_thread_stack_node(struct task_struct *tsk, int node)
392{
393 unsigned long *stack;
394 stack = kmem_cache_alloc_node(thread_stack_cache, THREADINFO_GFP, node);
395 stack = kasan_reset_tag(stack);
396 tsk->stack = stack;
397 return stack ? 0 : -ENOMEM;
398}
399
400static void free_thread_stack(struct task_struct *tsk)
401{
402 thread_stack_delayed_free(tsk);
403 tsk->stack = NULL;
404}
405
406void thread_stack_cache_init(void)
407{
408 thread_stack_cache = kmem_cache_create_usercopy("thread_stack",
409 THREAD_SIZE, THREAD_SIZE, 0, 0,
410 THREAD_SIZE, NULL);
411 BUG_ON(thread_stack_cache == NULL);
412}
413
414# endif /* THREAD_SIZE >= PAGE_SIZE || defined(CONFIG_VMAP_STACK) */
415
416/* SLAB cache for signal_struct structures (tsk->signal) */
417static struct kmem_cache *signal_cachep;
418
419/* SLAB cache for sighand_struct structures (tsk->sighand) */
420struct kmem_cache *sighand_cachep;
421
422/* SLAB cache for files_struct structures (tsk->files) */
423struct kmem_cache *files_cachep;
424
425/* SLAB cache for fs_struct structures (tsk->fs) */
426struct kmem_cache *fs_cachep;
427
428/* SLAB cache for vm_area_struct structures */
429static struct kmem_cache *vm_area_cachep;
430
431/* SLAB cache for mm_struct structures (tsk->mm) */
432static struct kmem_cache *mm_cachep;
433
434#ifdef CONFIG_PER_VMA_LOCK
435
436/* SLAB cache for vm_area_struct.lock */
437static struct kmem_cache *vma_lock_cachep;
438
439static bool vma_lock_alloc(struct vm_area_struct *vma)
440{
441 vma->vm_lock = kmem_cache_alloc(vma_lock_cachep, GFP_KERNEL);
442 if (!vma->vm_lock)
443 return false;
444
445 init_rwsem(&vma->vm_lock->lock);
446 vma->vm_lock_seq = -1;
447
448 return true;
449}
450
451static inline void vma_lock_free(struct vm_area_struct *vma)
452{
453 kmem_cache_free(vma_lock_cachep, vma->vm_lock);
454}
455
456#else /* CONFIG_PER_VMA_LOCK */
457
458static inline bool vma_lock_alloc(struct vm_area_struct *vma) { return true; }
459static inline void vma_lock_free(struct vm_area_struct *vma) {}
460
461#endif /* CONFIG_PER_VMA_LOCK */
462
463struct vm_area_struct *vm_area_alloc(struct mm_struct *mm)
464{
465 struct vm_area_struct *vma;
466
467 vma = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
468 if (!vma)
469 return NULL;
470
471 vma_init(vma, mm);
472 if (!vma_lock_alloc(vma)) {
473 kmem_cache_free(vm_area_cachep, vma);
474 return NULL;
475 }
476
477 return vma;
478}
479
480struct vm_area_struct *vm_area_dup(struct vm_area_struct *orig)
481{
482 struct vm_area_struct *new = kmem_cache_alloc(vm_area_cachep, GFP_KERNEL);
483
484 if (!new)
485 return NULL;
486
487 ASSERT_EXCLUSIVE_WRITER(orig->vm_flags);
488 ASSERT_EXCLUSIVE_WRITER(orig->vm_file);
489 /*
490 * orig->shared.rb may be modified concurrently, but the clone
491 * will be reinitialized.
492 */
493 data_race(memcpy(new, orig, sizeof(*new)));
494 if (!vma_lock_alloc(new)) {
495 kmem_cache_free(vm_area_cachep, new);
496 return NULL;
497 }
498 INIT_LIST_HEAD(&new->anon_vma_chain);
499 vma_numab_state_init(new);
500 dup_anon_vma_name(orig, new);
501
502 return new;
503}
504
505void __vm_area_free(struct vm_area_struct *vma)
506{
507 vma_numab_state_free(vma);
508 free_anon_vma_name(vma);
509 vma_lock_free(vma);
510 kmem_cache_free(vm_area_cachep, vma);
511}
512
513#ifdef CONFIG_PER_VMA_LOCK
514static void vm_area_free_rcu_cb(struct rcu_head *head)
515{
516 struct vm_area_struct *vma = container_of(head, struct vm_area_struct,
517 vm_rcu);
518
519 /* The vma should not be locked while being destroyed. */
520 VM_BUG_ON_VMA(rwsem_is_locked(&vma->vm_lock->lock), vma);
521 __vm_area_free(vma);
522}
523#endif
524
525void vm_area_free(struct vm_area_struct *vma)
526{
527#ifdef CONFIG_PER_VMA_LOCK
528 call_rcu(&vma->vm_rcu, vm_area_free_rcu_cb);
529#else
530 __vm_area_free(vma);
531#endif
532}
533
534static void account_kernel_stack(struct task_struct *tsk, int account)
535{
536 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
537 struct vm_struct *vm = task_stack_vm_area(tsk);
538 int i;
539
540 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
541 mod_lruvec_page_state(vm->pages[i], NR_KERNEL_STACK_KB,
542 account * (PAGE_SIZE / 1024));
543 } else {
544 void *stack = task_stack_page(tsk);
545
546 /* All stack pages are in the same node. */
547 mod_lruvec_kmem_state(stack, NR_KERNEL_STACK_KB,
548 account * (THREAD_SIZE / 1024));
549 }
550}
551
552void exit_task_stack_account(struct task_struct *tsk)
553{
554 account_kernel_stack(tsk, -1);
555
556 if (IS_ENABLED(CONFIG_VMAP_STACK)) {
557 struct vm_struct *vm;
558 int i;
559
560 vm = task_stack_vm_area(tsk);
561 for (i = 0; i < THREAD_SIZE / PAGE_SIZE; i++)
562 memcg_kmem_uncharge_page(vm->pages[i], 0);
563 }
564}
565
566static void release_task_stack(struct task_struct *tsk)
567{
568 if (WARN_ON(READ_ONCE(tsk->__state) != TASK_DEAD))
569 return; /* Better to leak the stack than to free prematurely */
570
571 free_thread_stack(tsk);
572}
573
574#ifdef CONFIG_THREAD_INFO_IN_TASK
575void put_task_stack(struct task_struct *tsk)
576{
577 if (refcount_dec_and_test(&tsk->stack_refcount))
578 release_task_stack(tsk);
579}
580#endif
581
582void free_task(struct task_struct *tsk)
583{
584#ifdef CONFIG_SECCOMP
585 WARN_ON_ONCE(tsk->seccomp.filter);
586#endif
587 release_user_cpus_ptr(tsk);
588 scs_release(tsk);
589
590#ifndef CONFIG_THREAD_INFO_IN_TASK
591 /*
592 * The task is finally done with both the stack and thread_info,
593 * so free both.
594 */
595 release_task_stack(tsk);
596#else
597 /*
598 * If the task had a separate stack allocation, it should be gone
599 * by now.
600 */
601 WARN_ON_ONCE(refcount_read(&tsk->stack_refcount) != 0);
602#endif
603 rt_mutex_debug_task_free(tsk);
604 ftrace_graph_exit_task(tsk);
605 arch_release_task_struct(tsk);
606 if (tsk->flags & PF_KTHREAD)
607 free_kthread_struct(tsk);
608 bpf_task_storage_free(tsk);
609 free_task_struct(tsk);
610}
611EXPORT_SYMBOL(free_task);
612
613static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
614{
615 struct file *exe_file;
616
617 exe_file = get_mm_exe_file(oldmm);
618 RCU_INIT_POINTER(mm->exe_file, exe_file);
619 /*
620 * We depend on the oldmm having properly denied write access to the
621 * exe_file already.
622 */
623 if (exe_file && deny_write_access(exe_file))
624 pr_warn_once("deny_write_access() failed in %s\n", __func__);
625}
626
627#ifdef CONFIG_MMU
628static __latent_entropy int dup_mmap(struct mm_struct *mm,
629 struct mm_struct *oldmm)
630{
631 struct vm_area_struct *mpnt, *tmp;
632 int retval;
633 unsigned long charge = 0;
634 LIST_HEAD(uf);
635 VMA_ITERATOR(vmi, mm, 0);
636
637 uprobe_start_dup_mmap();
638 if (mmap_write_lock_killable(oldmm)) {
639 retval = -EINTR;
640 goto fail_uprobe_end;
641 }
642 flush_cache_dup_mm(oldmm);
643 uprobe_dup_mmap(oldmm, mm);
644 /*
645 * Not linked in yet - no deadlock potential:
646 */
647 mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
648
649 /* No ordering required: file already has been exposed. */
650 dup_mm_exe_file(mm, oldmm);
651
652 mm->total_vm = oldmm->total_vm;
653 mm->data_vm = oldmm->data_vm;
654 mm->exec_vm = oldmm->exec_vm;
655 mm->stack_vm = oldmm->stack_vm;
656
657 retval = ksm_fork(mm, oldmm);
658 if (retval)
659 goto out;
660 khugepaged_fork(mm, oldmm);
661
662 /* Use __mt_dup() to efficiently build an identical maple tree. */
663 retval = __mt_dup(&oldmm->mm_mt, &mm->mm_mt, GFP_KERNEL);
664 if (unlikely(retval))
665 goto out;
666
667 mt_clear_in_rcu(vmi.mas.tree);
668 for_each_vma(vmi, mpnt) {
669 struct file *file;
670
671 vma_start_write(mpnt);
672 if (mpnt->vm_flags & VM_DONTCOPY) {
673 retval = vma_iter_clear_gfp(&vmi, mpnt->vm_start,
674 mpnt->vm_end, GFP_KERNEL);
675 if (retval)
676 goto loop_out;
677
678 vm_stat_account(mm, mpnt->vm_flags, -vma_pages(mpnt));
679 continue;
680 }
681 charge = 0;
682 /*
683 * Don't duplicate many vmas if we've been oom-killed (for
684 * example)
685 */
686 if (fatal_signal_pending(current)) {
687 retval = -EINTR;
688 goto loop_out;
689 }
690 if (mpnt->vm_flags & VM_ACCOUNT) {
691 unsigned long len = vma_pages(mpnt);
692
693 if (security_vm_enough_memory_mm(oldmm, len)) /* sic */
694 goto fail_nomem;
695 charge = len;
696 }
697 tmp = vm_area_dup(mpnt);
698 if (!tmp)
699 goto fail_nomem;
700 retval = vma_dup_policy(mpnt, tmp);
701 if (retval)
702 goto fail_nomem_policy;
703 tmp->vm_mm = mm;
704 retval = dup_userfaultfd(tmp, &uf);
705 if (retval)
706 goto fail_nomem_anon_vma_fork;
707 if (tmp->vm_flags & VM_WIPEONFORK) {
708 /*
709 * VM_WIPEONFORK gets a clean slate in the child.
710 * Don't prepare anon_vma until fault since we don't
711 * copy page for current vma.
712 */
713 tmp->anon_vma = NULL;
714 } else if (anon_vma_fork(tmp, mpnt))
715 goto fail_nomem_anon_vma_fork;
716 vm_flags_clear(tmp, VM_LOCKED_MASK);
717 file = tmp->vm_file;
718 if (file) {
719 struct address_space *mapping = file->f_mapping;
720
721 get_file(file);
722 i_mmap_lock_write(mapping);
723 if (vma_is_shared_maywrite(tmp))
724 mapping_allow_writable(mapping);
725 flush_dcache_mmap_lock(mapping);
726 /* insert tmp into the share list, just after mpnt */
727 vma_interval_tree_insert_after(tmp, mpnt,
728 &mapping->i_mmap);
729 flush_dcache_mmap_unlock(mapping);
730 i_mmap_unlock_write(mapping);
731 }
732
733 /*
734 * Copy/update hugetlb private vma information.
735 */
736 if (is_vm_hugetlb_page(tmp))
737 hugetlb_dup_vma_private(tmp);
738
739 /*
740 * Link the vma into the MT. After using __mt_dup(), memory
741 * allocation is not necessary here, so it cannot fail.
742 */
743 vma_iter_bulk_store(&vmi, tmp);
744
745 mm->map_count++;
746 if (!(tmp->vm_flags & VM_WIPEONFORK))
747 retval = copy_page_range(tmp, mpnt);
748
749 if (tmp->vm_ops && tmp->vm_ops->open)
750 tmp->vm_ops->open(tmp);
751
752 if (retval) {
753 mpnt = vma_next(&vmi);
754 goto loop_out;
755 }
756 }
757 /* a new mm has just been created */
758 retval = arch_dup_mmap(oldmm, mm);
759loop_out:
760 vma_iter_free(&vmi);
761 if (!retval) {
762 mt_set_in_rcu(vmi.mas.tree);
763 } else if (mpnt) {
764 /*
765 * The entire maple tree has already been duplicated. If the
766 * mmap duplication fails, mark the failure point with
767 * XA_ZERO_ENTRY. In exit_mmap(), if this marker is encountered,
768 * stop releasing VMAs that have not been duplicated after this
769 * point.
770 */
771 mas_set_range(&vmi.mas, mpnt->vm_start, mpnt->vm_end - 1);
772 mas_store(&vmi.mas, XA_ZERO_ENTRY);
773 }
774out:
775 mmap_write_unlock(mm);
776 flush_tlb_mm(oldmm);
777 mmap_write_unlock(oldmm);
778 dup_userfaultfd_complete(&uf);
779fail_uprobe_end:
780 uprobe_end_dup_mmap();
781 return retval;
782
783fail_nomem_anon_vma_fork:
784 mpol_put(vma_policy(tmp));
785fail_nomem_policy:
786 vm_area_free(tmp);
787fail_nomem:
788 retval = -ENOMEM;
789 vm_unacct_memory(charge);
790 goto loop_out;
791}
792
793static inline int mm_alloc_pgd(struct mm_struct *mm)
794{
795 mm->pgd = pgd_alloc(mm);
796 if (unlikely(!mm->pgd))
797 return -ENOMEM;
798 return 0;
799}
800
801static inline void mm_free_pgd(struct mm_struct *mm)
802{
803 pgd_free(mm, mm->pgd);
804}
805#else
806static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
807{
808 mmap_write_lock(oldmm);
809 dup_mm_exe_file(mm, oldmm);
810 mmap_write_unlock(oldmm);
811 return 0;
812}
813#define mm_alloc_pgd(mm) (0)
814#define mm_free_pgd(mm)
815#endif /* CONFIG_MMU */
816
817static void check_mm(struct mm_struct *mm)
818{
819 int i;
820
821 BUILD_BUG_ON_MSG(ARRAY_SIZE(resident_page_types) != NR_MM_COUNTERS,
822 "Please make sure 'struct resident_page_types[]' is updated as well");
823
824 for (i = 0; i < NR_MM_COUNTERS; i++) {
825 long x = percpu_counter_sum(&mm->rss_stat[i]);
826
827 if (unlikely(x))
828 pr_alert("BUG: Bad rss-counter state mm:%p type:%s val:%ld\n",
829 mm, resident_page_types[i], x);
830 }
831
832 if (mm_pgtables_bytes(mm))
833 pr_alert("BUG: non-zero pgtables_bytes on freeing mm: %ld\n",
834 mm_pgtables_bytes(mm));
835
836#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
837 VM_BUG_ON_MM(mm->pmd_huge_pte, mm);
838#endif
839}
840
841#define allocate_mm() (kmem_cache_alloc(mm_cachep, GFP_KERNEL))
842#define free_mm(mm) (kmem_cache_free(mm_cachep, (mm)))
843
844static void do_check_lazy_tlb(void *arg)
845{
846 struct mm_struct *mm = arg;
847
848 WARN_ON_ONCE(current->active_mm == mm);
849}
850
851static void do_shoot_lazy_tlb(void *arg)
852{
853 struct mm_struct *mm = arg;
854
855 if (current->active_mm == mm) {
856 WARN_ON_ONCE(current->mm);
857 current->active_mm = &init_mm;
858 switch_mm(mm, &init_mm, current);
859 }
860}
861
862static void cleanup_lazy_tlbs(struct mm_struct *mm)
863{
864 if (!IS_ENABLED(CONFIG_MMU_LAZY_TLB_SHOOTDOWN)) {
865 /*
866 * In this case, lazy tlb mms are refounted and would not reach
867 * __mmdrop until all CPUs have switched away and mmdrop()ed.
868 */
869 return;
870 }
871
872 /*
873 * Lazy mm shootdown does not refcount "lazy tlb mm" usage, rather it
874 * requires lazy mm users to switch to another mm when the refcount
875 * drops to zero, before the mm is freed. This requires IPIs here to
876 * switch kernel threads to init_mm.
877 *
878 * archs that use IPIs to flush TLBs can piggy-back that lazy tlb mm
879 * switch with the final userspace teardown TLB flush which leaves the
880 * mm lazy on this CPU but no others, reducing the need for additional
881 * IPIs here. There are cases where a final IPI is still required here,
882 * such as the final mmdrop being performed on a different CPU than the
883 * one exiting, or kernel threads using the mm when userspace exits.
884 *
885 * IPI overheads have not found to be expensive, but they could be
886 * reduced in a number of possible ways, for example (roughly
887 * increasing order of complexity):
888 * - The last lazy reference created by exit_mm() could instead switch
889 * to init_mm, however it's probable this will run on the same CPU
890 * immediately afterwards, so this may not reduce IPIs much.
891 * - A batch of mms requiring IPIs could be gathered and freed at once.
892 * - CPUs store active_mm where it can be remotely checked without a
893 * lock, to filter out false-positives in the cpumask.
894 * - After mm_users or mm_count reaches zero, switching away from the
895 * mm could clear mm_cpumask to reduce some IPIs, perhaps together
896 * with some batching or delaying of the final IPIs.
897 * - A delayed freeing and RCU-like quiescing sequence based on mm
898 * switching to avoid IPIs completely.
899 */
900 on_each_cpu_mask(mm_cpumask(mm), do_shoot_lazy_tlb, (void *)mm, 1);
901 if (IS_ENABLED(CONFIG_DEBUG_VM_SHOOT_LAZIES))
902 on_each_cpu(do_check_lazy_tlb, (void *)mm, 1);
903}
904
905/*
906 * Called when the last reference to the mm
907 * is dropped: either by a lazy thread or by
908 * mmput. Free the page directory and the mm.
909 */
910void __mmdrop(struct mm_struct *mm)
911{
912 BUG_ON(mm == &init_mm);
913 WARN_ON_ONCE(mm == current->mm);
914
915 /* Ensure no CPUs are using this as their lazy tlb mm */
916 cleanup_lazy_tlbs(mm);
917
918 WARN_ON_ONCE(mm == current->active_mm);
919 mm_free_pgd(mm);
920 destroy_context(mm);
921 mmu_notifier_subscriptions_destroy(mm);
922 check_mm(mm);
923 put_user_ns(mm->user_ns);
924 mm_pasid_drop(mm);
925 mm_destroy_cid(mm);
926 percpu_counter_destroy_many(mm->rss_stat, NR_MM_COUNTERS);
927
928 free_mm(mm);
929}
930EXPORT_SYMBOL_GPL(__mmdrop);
931
932static void mmdrop_async_fn(struct work_struct *work)
933{
934 struct mm_struct *mm;
935
936 mm = container_of(work, struct mm_struct, async_put_work);
937 __mmdrop(mm);
938}
939
940static void mmdrop_async(struct mm_struct *mm)
941{
942 if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
943 INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
944 schedule_work(&mm->async_put_work);
945 }
946}
947
948static inline void free_signal_struct(struct signal_struct *sig)
949{
950 taskstats_tgid_free(sig);
951 sched_autogroup_exit(sig);
952 /*
953 * __mmdrop is not safe to call from softirq context on x86 due to
954 * pgd_dtor so postpone it to the async context
955 */
956 if (sig->oom_mm)
957 mmdrop_async(sig->oom_mm);
958 kmem_cache_free(signal_cachep, sig);
959}
960
961static inline void put_signal_struct(struct signal_struct *sig)
962{
963 if (refcount_dec_and_test(&sig->sigcnt))
964 free_signal_struct(sig);
965}
966
967void __put_task_struct(struct task_struct *tsk)
968{
969 WARN_ON(!tsk->exit_state);
970 WARN_ON(refcount_read(&tsk->usage));
971 WARN_ON(tsk == current);
972
973 io_uring_free(tsk);
974 cgroup_free(tsk);
975 task_numa_free(tsk, true);
976 security_task_free(tsk);
977 exit_creds(tsk);
978 delayacct_tsk_free(tsk);
979 put_signal_struct(tsk->signal);
980 sched_core_free(tsk);
981 free_task(tsk);
982}
983EXPORT_SYMBOL_GPL(__put_task_struct);
984
985void __put_task_struct_rcu_cb(struct rcu_head *rhp)
986{
987 struct task_struct *task = container_of(rhp, struct task_struct, rcu);
988
989 __put_task_struct(task);
990}
991EXPORT_SYMBOL_GPL(__put_task_struct_rcu_cb);
992
993void __init __weak arch_task_cache_init(void) { }
994
995/*
996 * set_max_threads
997 */
998static void set_max_threads(unsigned int max_threads_suggested)
999{
1000 u64 threads;
1001 unsigned long nr_pages = totalram_pages();
1002
1003 /*
1004 * The number of threads shall be limited such that the thread
1005 * structures may only consume a small part of the available memory.
1006 */
1007 if (fls64(nr_pages) + fls64(PAGE_SIZE) > 64)
1008 threads = MAX_THREADS;
1009 else
1010 threads = div64_u64((u64) nr_pages * (u64) PAGE_SIZE,
1011 (u64) THREAD_SIZE * 8UL);
1012
1013 if (threads > max_threads_suggested)
1014 threads = max_threads_suggested;
1015
1016 max_threads = clamp_t(u64, threads, MIN_THREADS, MAX_THREADS);
1017}
1018
1019#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
1020/* Initialized by the architecture: */
1021int arch_task_struct_size __read_mostly;
1022#endif
1023
1024static void task_struct_whitelist(unsigned long *offset, unsigned long *size)
1025{
1026 /* Fetch thread_struct whitelist for the architecture. */
1027 arch_thread_struct_whitelist(offset, size);
1028
1029 /*
1030 * Handle zero-sized whitelist or empty thread_struct, otherwise
1031 * adjust offset to position of thread_struct in task_struct.
1032 */
1033 if (unlikely(*size == 0))
1034 *offset = 0;
1035 else
1036 *offset += offsetof(struct task_struct, thread);
1037}
1038
1039void __init fork_init(void)
1040{
1041 int i;
1042#ifndef ARCH_MIN_TASKALIGN
1043#define ARCH_MIN_TASKALIGN 0
1044#endif
1045 int align = max_t(int, L1_CACHE_BYTES, ARCH_MIN_TASKALIGN);
1046 unsigned long useroffset, usersize;
1047
1048 /* create a slab on which task_structs can be allocated */
1049 task_struct_whitelist(&useroffset, &usersize);
1050 task_struct_cachep = kmem_cache_create_usercopy("task_struct",
1051 arch_task_struct_size, align,
1052 SLAB_PANIC|SLAB_ACCOUNT,
1053 useroffset, usersize, NULL);
1054
1055 /* do the arch specific task caches init */
1056 arch_task_cache_init();
1057
1058 set_max_threads(MAX_THREADS);
1059
1060 init_task.signal->rlim[RLIMIT_NPROC].rlim_cur = max_threads/2;
1061 init_task.signal->rlim[RLIMIT_NPROC].rlim_max = max_threads/2;
1062 init_task.signal->rlim[RLIMIT_SIGPENDING] =
1063 init_task.signal->rlim[RLIMIT_NPROC];
1064
1065 for (i = 0; i < UCOUNT_COUNTS; i++)
1066 init_user_ns.ucount_max[i] = max_threads/2;
1067
1068 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_NPROC, RLIM_INFINITY);
1069 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MSGQUEUE, RLIM_INFINITY);
1070 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_SIGPENDING, RLIM_INFINITY);
1071 set_userns_rlimit_max(&init_user_ns, UCOUNT_RLIMIT_MEMLOCK, RLIM_INFINITY);
1072
1073#ifdef CONFIG_VMAP_STACK
1074 cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "fork:vm_stack_cache",
1075 NULL, free_vm_stack_cache);
1076#endif
1077
1078 scs_init();
1079
1080 lockdep_init_task(&init_task);
1081 uprobes_init();
1082}
1083
1084int __weak arch_dup_task_struct(struct task_struct *dst,
1085 struct task_struct *src)
1086{
1087 *dst = *src;
1088 return 0;
1089}
1090
1091void set_task_stack_end_magic(struct task_struct *tsk)
1092{
1093 unsigned long *stackend;
1094
1095 stackend = end_of_stack(tsk);
1096 *stackend = STACK_END_MAGIC; /* for overflow detection */
1097}
1098
1099static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
1100{
1101 struct task_struct *tsk;
1102 int err;
1103
1104 if (node == NUMA_NO_NODE)
1105 node = tsk_fork_get_node(orig);
1106 tsk = alloc_task_struct_node(node);
1107 if (!tsk)
1108 return NULL;
1109
1110 err = arch_dup_task_struct(tsk, orig);
1111 if (err)
1112 goto free_tsk;
1113
1114 err = alloc_thread_stack_node(tsk, node);
1115 if (err)
1116 goto free_tsk;
1117
1118#ifdef CONFIG_THREAD_INFO_IN_TASK
1119 refcount_set(&tsk->stack_refcount, 1);
1120#endif
1121 account_kernel_stack(tsk, 1);
1122
1123 err = scs_prepare(tsk, node);
1124 if (err)
1125 goto free_stack;
1126
1127#ifdef CONFIG_SECCOMP
1128 /*
1129 * We must handle setting up seccomp filters once we're under
1130 * the sighand lock in case orig has changed between now and
1131 * then. Until then, filter must be NULL to avoid messing up
1132 * the usage counts on the error path calling free_task.
1133 */
1134 tsk->seccomp.filter = NULL;
1135#endif
1136
1137 setup_thread_stack(tsk, orig);
1138 clear_user_return_notifier(tsk);
1139 clear_tsk_need_resched(tsk);
1140 set_task_stack_end_magic(tsk);
1141 clear_syscall_work_syscall_user_dispatch(tsk);
1142
1143#ifdef CONFIG_STACKPROTECTOR
1144 tsk->stack_canary = get_random_canary();
1145#endif
1146 if (orig->cpus_ptr == &orig->cpus_mask)
1147 tsk->cpus_ptr = &tsk->cpus_mask;
1148 dup_user_cpus_ptr(tsk, orig, node);
1149
1150 /*
1151 * One for the user space visible state that goes away when reaped.
1152 * One for the scheduler.
1153 */
1154 refcount_set(&tsk->rcu_users, 2);
1155 /* One for the rcu users */
1156 refcount_set(&tsk->usage, 1);
1157#ifdef CONFIG_BLK_DEV_IO_TRACE
1158 tsk->btrace_seq = 0;
1159#endif
1160 tsk->splice_pipe = NULL;
1161 tsk->task_frag.page = NULL;
1162 tsk->wake_q.next = NULL;
1163 tsk->worker_private = NULL;
1164
1165 kcov_task_init(tsk);
1166 kmsan_task_create(tsk);
1167 kmap_local_fork(tsk);
1168
1169#ifdef CONFIG_FAULT_INJECTION
1170 tsk->fail_nth = 0;
1171#endif
1172
1173#ifdef CONFIG_BLK_CGROUP
1174 tsk->throttle_disk = NULL;
1175 tsk->use_memdelay = 0;
1176#endif
1177
1178#ifdef CONFIG_ARCH_HAS_CPU_PASID
1179 tsk->pasid_activated = 0;
1180#endif
1181
1182#ifdef CONFIG_MEMCG
1183 tsk->active_memcg = NULL;
1184#endif
1185
1186#ifdef CONFIG_CPU_SUP_INTEL
1187 tsk->reported_split_lock = 0;
1188#endif
1189
1190#ifdef CONFIG_SCHED_MM_CID
1191 tsk->mm_cid = -1;
1192 tsk->last_mm_cid = -1;
1193 tsk->mm_cid_active = 0;
1194 tsk->migrate_from_cpu = -1;
1195#endif
1196 return tsk;
1197
1198free_stack:
1199 exit_task_stack_account(tsk);
1200 free_thread_stack(tsk);
1201free_tsk:
1202 free_task_struct(tsk);
1203 return NULL;
1204}
1205
1206__cacheline_aligned_in_smp DEFINE_SPINLOCK(mmlist_lock);
1207
1208static unsigned long default_dump_filter = MMF_DUMP_FILTER_DEFAULT;
1209
1210static int __init coredump_filter_setup(char *s)
1211{
1212 default_dump_filter =
1213 (simple_strtoul(s, NULL, 0) << MMF_DUMP_FILTER_SHIFT) &
1214 MMF_DUMP_FILTER_MASK;
1215 return 1;
1216}
1217
1218__setup("coredump_filter=", coredump_filter_setup);
1219
1220#include <linux/init_task.h>
1221
1222static void mm_init_aio(struct mm_struct *mm)
1223{
1224#ifdef CONFIG_AIO
1225 spin_lock_init(&mm->ioctx_lock);
1226 mm->ioctx_table = NULL;
1227#endif
1228}
1229
1230static __always_inline void mm_clear_owner(struct mm_struct *mm,
1231 struct task_struct *p)
1232{
1233#ifdef CONFIG_MEMCG
1234 if (mm->owner == p)
1235 WRITE_ONCE(mm->owner, NULL);
1236#endif
1237}
1238
1239static void mm_init_owner(struct mm_struct *mm, struct task_struct *p)
1240{
1241#ifdef CONFIG_MEMCG
1242 mm->owner = p;
1243#endif
1244}
1245
1246static void mm_init_uprobes_state(struct mm_struct *mm)
1247{
1248#ifdef CONFIG_UPROBES
1249 mm->uprobes_state.xol_area = NULL;
1250#endif
1251}
1252
1253static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
1254 struct user_namespace *user_ns)
1255{
1256 mt_init_flags(&mm->mm_mt, MM_MT_FLAGS);
1257 mt_set_external_lock(&mm->mm_mt, &mm->mmap_lock);
1258 atomic_set(&mm->mm_users, 1);
1259 atomic_set(&mm->mm_count, 1);
1260 seqcount_init(&mm->write_protect_seq);
1261 mmap_init_lock(mm);
1262 INIT_LIST_HEAD(&mm->mmlist);
1263#ifdef CONFIG_PER_VMA_LOCK
1264 mm->mm_lock_seq = 0;
1265#endif
1266 mm_pgtables_bytes_init(mm);
1267 mm->map_count = 0;
1268 mm->locked_vm = 0;
1269 atomic64_set(&mm->pinned_vm, 0);
1270 memset(&mm->rss_stat, 0, sizeof(mm->rss_stat));
1271 spin_lock_init(&mm->page_table_lock);
1272 spin_lock_init(&mm->arg_lock);
1273 mm_init_cpumask(mm);
1274 mm_init_aio(mm);
1275 mm_init_owner(mm, p);
1276 mm_pasid_init(mm);
1277 RCU_INIT_POINTER(mm->exe_file, NULL);
1278 mmu_notifier_subscriptions_init(mm);
1279 init_tlb_flush_pending(mm);
1280#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
1281 mm->pmd_huge_pte = NULL;
1282#endif
1283 mm_init_uprobes_state(mm);
1284 hugetlb_count_init(mm);
1285
1286 if (current->mm) {
1287 mm->flags = mmf_init_flags(current->mm->flags);
1288 mm->def_flags = current->mm->def_flags & VM_INIT_DEF_MASK;
1289 } else {
1290 mm->flags = default_dump_filter;
1291 mm->def_flags = 0;
1292 }
1293
1294 if (mm_alloc_pgd(mm))
1295 goto fail_nopgd;
1296
1297 if (init_new_context(p, mm))
1298 goto fail_nocontext;
1299
1300 if (mm_alloc_cid(mm))
1301 goto fail_cid;
1302
1303 if (percpu_counter_init_many(mm->rss_stat, 0, GFP_KERNEL_ACCOUNT,
1304 NR_MM_COUNTERS))
1305 goto fail_pcpu;
1306
1307 mm->user_ns = get_user_ns(user_ns);
1308 lru_gen_init_mm(mm);
1309 return mm;
1310
1311fail_pcpu:
1312 mm_destroy_cid(mm);
1313fail_cid:
1314 destroy_context(mm);
1315fail_nocontext:
1316 mm_free_pgd(mm);
1317fail_nopgd:
1318 free_mm(mm);
1319 return NULL;
1320}
1321
1322/*
1323 * Allocate and initialize an mm_struct.
1324 */
1325struct mm_struct *mm_alloc(void)
1326{
1327 struct mm_struct *mm;
1328
1329 mm = allocate_mm();
1330 if (!mm)
1331 return NULL;
1332
1333 memset(mm, 0, sizeof(*mm));
1334 return mm_init(mm, current, current_user_ns());
1335}
1336
1337static inline void __mmput(struct mm_struct *mm)
1338{
1339 VM_BUG_ON(atomic_read(&mm->mm_users));
1340
1341 uprobe_clear_state(mm);
1342 exit_aio(mm);
1343 ksm_exit(mm);
1344 khugepaged_exit(mm); /* must run before exit_mmap */
1345 exit_mmap(mm);
1346 mm_put_huge_zero_page(mm);
1347 set_mm_exe_file(mm, NULL);
1348 if (!list_empty(&mm->mmlist)) {
1349 spin_lock(&mmlist_lock);
1350 list_del(&mm->mmlist);
1351 spin_unlock(&mmlist_lock);
1352 }
1353 if (mm->binfmt)
1354 module_put(mm->binfmt->module);
1355 lru_gen_del_mm(mm);
1356 mmdrop(mm);
1357}
1358
1359/*
1360 * Decrement the use count and release all resources for an mm.
1361 */
1362void mmput(struct mm_struct *mm)
1363{
1364 might_sleep();
1365
1366 if (atomic_dec_and_test(&mm->mm_users))
1367 __mmput(mm);
1368}
1369EXPORT_SYMBOL_GPL(mmput);
1370
1371#ifdef CONFIG_MMU
1372static void mmput_async_fn(struct work_struct *work)
1373{
1374 struct mm_struct *mm = container_of(work, struct mm_struct,
1375 async_put_work);
1376
1377 __mmput(mm);
1378}
1379
1380void mmput_async(struct mm_struct *mm)
1381{
1382 if (atomic_dec_and_test(&mm->mm_users)) {
1383 INIT_WORK(&mm->async_put_work, mmput_async_fn);
1384 schedule_work(&mm->async_put_work);
1385 }
1386}
1387EXPORT_SYMBOL_GPL(mmput_async);
1388#endif
1389
1390/**
1391 * set_mm_exe_file - change a reference to the mm's executable file
1392 * @mm: The mm to change.
1393 * @new_exe_file: The new file to use.
1394 *
1395 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1396 *
1397 * Main users are mmput() and sys_execve(). Callers prevent concurrent
1398 * invocations: in mmput() nobody alive left, in execve it happens before
1399 * the new mm is made visible to anyone.
1400 *
1401 * Can only fail if new_exe_file != NULL.
1402 */
1403int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1404{
1405 struct file *old_exe_file;
1406
1407 /*
1408 * It is safe to dereference the exe_file without RCU as
1409 * this function is only called if nobody else can access
1410 * this mm -- see comment above for justification.
1411 */
1412 old_exe_file = rcu_dereference_raw(mm->exe_file);
1413
1414 if (new_exe_file) {
1415 /*
1416 * We expect the caller (i.e., sys_execve) to already denied
1417 * write access, so this is unlikely to fail.
1418 */
1419 if (unlikely(deny_write_access(new_exe_file)))
1420 return -EACCES;
1421 get_file(new_exe_file);
1422 }
1423 rcu_assign_pointer(mm->exe_file, new_exe_file);
1424 if (old_exe_file) {
1425 allow_write_access(old_exe_file);
1426 fput(old_exe_file);
1427 }
1428 return 0;
1429}
1430
1431/**
1432 * replace_mm_exe_file - replace a reference to the mm's executable file
1433 * @mm: The mm to change.
1434 * @new_exe_file: The new file to use.
1435 *
1436 * This changes mm's executable file (shown as symlink /proc/[pid]/exe).
1437 *
1438 * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
1439 */
1440int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
1441{
1442 struct vm_area_struct *vma;
1443 struct file *old_exe_file;
1444 int ret = 0;
1445
1446 /* Forbid mm->exe_file change if old file still mapped. */
1447 old_exe_file = get_mm_exe_file(mm);
1448 if (old_exe_file) {
1449 VMA_ITERATOR(vmi, mm, 0);
1450 mmap_read_lock(mm);
1451 for_each_vma(vmi, vma) {
1452 if (!vma->vm_file)
1453 continue;
1454 if (path_equal(&vma->vm_file->f_path,
1455 &old_exe_file->f_path)) {
1456 ret = -EBUSY;
1457 break;
1458 }
1459 }
1460 mmap_read_unlock(mm);
1461 fput(old_exe_file);
1462 if (ret)
1463 return ret;
1464 }
1465
1466 ret = deny_write_access(new_exe_file);
1467 if (ret)
1468 return -EACCES;
1469 get_file(new_exe_file);
1470
1471 /* set the new file */
1472 mmap_write_lock(mm);
1473 old_exe_file = rcu_dereference_raw(mm->exe_file);
1474 rcu_assign_pointer(mm->exe_file, new_exe_file);
1475 mmap_write_unlock(mm);
1476
1477 if (old_exe_file) {
1478 allow_write_access(old_exe_file);
1479 fput(old_exe_file);
1480 }
1481 return 0;
1482}
1483
1484/**
1485 * get_mm_exe_file - acquire a reference to the mm's executable file
1486 * @mm: The mm of interest.
1487 *
1488 * Returns %NULL if mm has no associated executable file.
1489 * User must release file via fput().
1490 */
1491struct file *get_mm_exe_file(struct mm_struct *mm)
1492{
1493 struct file *exe_file;
1494
1495 rcu_read_lock();
1496 exe_file = get_file_rcu(&mm->exe_file);
1497 rcu_read_unlock();
1498 return exe_file;
1499}
1500
1501/**
1502 * get_task_exe_file - acquire a reference to the task's executable file
1503 * @task: The task.
1504 *
1505 * Returns %NULL if task's mm (if any) has no associated executable file or
1506 * this is a kernel thread with borrowed mm (see the comment above get_task_mm).
1507 * User must release file via fput().
1508 */
1509struct file *get_task_exe_file(struct task_struct *task)
1510{
1511 struct file *exe_file = NULL;
1512 struct mm_struct *mm;
1513
1514 task_lock(task);
1515 mm = task->mm;
1516 if (mm) {
1517 if (!(task->flags & PF_KTHREAD))
1518 exe_file = get_mm_exe_file(mm);
1519 }
1520 task_unlock(task);
1521 return exe_file;
1522}
1523
1524/**
1525 * get_task_mm - acquire a reference to the task's mm
1526 * @task: The task.
1527 *
1528 * Returns %NULL if the task has no mm. Checks PF_KTHREAD (meaning
1529 * this kernel workthread has transiently adopted a user mm with use_mm,
1530 * to do its AIO) is not set and if so returns a reference to it, after
1531 * bumping up the use count. User must release the mm via mmput()
1532 * after use. Typically used by /proc and ptrace.
1533 */
1534struct mm_struct *get_task_mm(struct task_struct *task)
1535{
1536 struct mm_struct *mm;
1537
1538 task_lock(task);
1539 mm = task->mm;
1540 if (mm) {
1541 if (task->flags & PF_KTHREAD)
1542 mm = NULL;
1543 else
1544 mmget(mm);
1545 }
1546 task_unlock(task);
1547 return mm;
1548}
1549EXPORT_SYMBOL_GPL(get_task_mm);
1550
1551struct mm_struct *mm_access(struct task_struct *task, unsigned int mode)
1552{
1553 struct mm_struct *mm;
1554 int err;
1555
1556 err = down_read_killable(&task->signal->exec_update_lock);
1557 if (err)
1558 return ERR_PTR(err);
1559
1560 mm = get_task_mm(task);
1561 if (mm && mm != current->mm &&
1562 !ptrace_may_access(task, mode)) {
1563 mmput(mm);
1564 mm = ERR_PTR(-EACCES);
1565 }
1566 up_read(&task->signal->exec_update_lock);
1567
1568 return mm;
1569}
1570
1571static void complete_vfork_done(struct task_struct *tsk)
1572{
1573 struct completion *vfork;
1574
1575 task_lock(tsk);
1576 vfork = tsk->vfork_done;
1577 if (likely(vfork)) {
1578 tsk->vfork_done = NULL;
1579 complete(vfork);
1580 }
1581 task_unlock(tsk);
1582}
1583
1584static int wait_for_vfork_done(struct task_struct *child,
1585 struct completion *vfork)
1586{
1587 unsigned int state = TASK_KILLABLE|TASK_FREEZABLE;
1588 int killed;
1589
1590 cgroup_enter_frozen();
1591 killed = wait_for_completion_state(vfork, state);
1592 cgroup_leave_frozen(false);
1593
1594 if (killed) {
1595 task_lock(child);
1596 child->vfork_done = NULL;
1597 task_unlock(child);
1598 }
1599
1600 put_task_struct(child);
1601 return killed;
1602}
1603
1604/* Please note the differences between mmput and mm_release.
1605 * mmput is called whenever we stop holding onto a mm_struct,
1606 * error success whatever.
1607 *
1608 * mm_release is called after a mm_struct has been removed
1609 * from the current process.
1610 *
1611 * This difference is important for error handling, when we
1612 * only half set up a mm_struct for a new process and need to restore
1613 * the old one. Because we mmput the new mm_struct before
1614 * restoring the old one. . .
1615 * Eric Biederman 10 January 1998
1616 */
1617static void mm_release(struct task_struct *tsk, struct mm_struct *mm)
1618{
1619 uprobe_free_utask(tsk);
1620
1621 /* Get rid of any cached register state */
1622 deactivate_mm(tsk, mm);
1623
1624 /*
1625 * Signal userspace if we're not exiting with a core dump
1626 * because we want to leave the value intact for debugging
1627 * purposes.
1628 */
1629 if (tsk->clear_child_tid) {
1630 if (atomic_read(&mm->mm_users) > 1) {
1631 /*
1632 * We don't check the error code - if userspace has
1633 * not set up a proper pointer then tough luck.
1634 */
1635 put_user(0, tsk->clear_child_tid);
1636 do_futex(tsk->clear_child_tid, FUTEX_WAKE,
1637 1, NULL, NULL, 0, 0);
1638 }
1639 tsk->clear_child_tid = NULL;
1640 }
1641
1642 /*
1643 * All done, finally we can wake up parent and return this mm to him.
1644 * Also kthread_stop() uses this completion for synchronization.
1645 */
1646 if (tsk->vfork_done)
1647 complete_vfork_done(tsk);
1648}
1649
1650void exit_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1651{
1652 futex_exit_release(tsk);
1653 mm_release(tsk, mm);
1654}
1655
1656void exec_mm_release(struct task_struct *tsk, struct mm_struct *mm)
1657{
1658 futex_exec_release(tsk);
1659 mm_release(tsk, mm);
1660}
1661
1662/**
1663 * dup_mm() - duplicates an existing mm structure
1664 * @tsk: the task_struct with which the new mm will be associated.
1665 * @oldmm: the mm to duplicate.
1666 *
1667 * Allocates a new mm structure and duplicates the provided @oldmm structure
1668 * content into it.
1669 *
1670 * Return: the duplicated mm or NULL on failure.
1671 */
1672static struct mm_struct *dup_mm(struct task_struct *tsk,
1673 struct mm_struct *oldmm)
1674{
1675 struct mm_struct *mm;
1676 int err;
1677
1678 mm = allocate_mm();
1679 if (!mm)
1680 goto fail_nomem;
1681
1682 memcpy(mm, oldmm, sizeof(*mm));
1683
1684 if (!mm_init(mm, tsk, mm->user_ns))
1685 goto fail_nomem;
1686
1687 err = dup_mmap(mm, oldmm);
1688 if (err)
1689 goto free_pt;
1690
1691 mm->hiwater_rss = get_mm_rss(mm);
1692 mm->hiwater_vm = mm->total_vm;
1693
1694 if (mm->binfmt && !try_module_get(mm->binfmt->module))
1695 goto free_pt;
1696
1697 return mm;
1698
1699free_pt:
1700 /* don't put binfmt in mmput, we haven't got module yet */
1701 mm->binfmt = NULL;
1702 mm_init_owner(mm, NULL);
1703 mmput(mm);
1704
1705fail_nomem:
1706 return NULL;
1707}
1708
1709static int copy_mm(unsigned long clone_flags, struct task_struct *tsk)
1710{
1711 struct mm_struct *mm, *oldmm;
1712
1713 tsk->min_flt = tsk->maj_flt = 0;
1714 tsk->nvcsw = tsk->nivcsw = 0;
1715#ifdef CONFIG_DETECT_HUNG_TASK
1716 tsk->last_switch_count = tsk->nvcsw + tsk->nivcsw;
1717 tsk->last_switch_time = 0;
1718#endif
1719
1720 tsk->mm = NULL;
1721 tsk->active_mm = NULL;
1722
1723 /*
1724 * Are we cloning a kernel thread?
1725 *
1726 * We need to steal a active VM for that..
1727 */
1728 oldmm = current->mm;
1729 if (!oldmm)
1730 return 0;
1731
1732 if (clone_flags & CLONE_VM) {
1733 mmget(oldmm);
1734 mm = oldmm;
1735 } else {
1736 mm = dup_mm(tsk, current->mm);
1737 if (!mm)
1738 return -ENOMEM;
1739 }
1740
1741 tsk->mm = mm;
1742 tsk->active_mm = mm;
1743 sched_mm_cid_fork(tsk);
1744 return 0;
1745}
1746
1747static int copy_fs(unsigned long clone_flags, struct task_struct *tsk)
1748{
1749 struct fs_struct *fs = current->fs;
1750 if (clone_flags & CLONE_FS) {
1751 /* tsk->fs is already what we want */
1752 spin_lock(&fs->lock);
1753 /* "users" and "in_exec" locked for check_unsafe_exec() */
1754 if (fs->in_exec) {
1755 spin_unlock(&fs->lock);
1756 return -EAGAIN;
1757 }
1758 fs->users++;
1759 spin_unlock(&fs->lock);
1760 return 0;
1761 }
1762 tsk->fs = copy_fs_struct(fs);
1763 if (!tsk->fs)
1764 return -ENOMEM;
1765 return 0;
1766}
1767
1768static int copy_files(unsigned long clone_flags, struct task_struct *tsk,
1769 int no_files)
1770{
1771 struct files_struct *oldf, *newf;
1772 int error = 0;
1773
1774 /*
1775 * A background process may not have any files ...
1776 */
1777 oldf = current->files;
1778 if (!oldf)
1779 goto out;
1780
1781 if (no_files) {
1782 tsk->files = NULL;
1783 goto out;
1784 }
1785
1786 if (clone_flags & CLONE_FILES) {
1787 atomic_inc(&oldf->count);
1788 goto out;
1789 }
1790
1791 newf = dup_fd(oldf, NR_OPEN_MAX, &error);
1792 if (!newf)
1793 goto out;
1794
1795 tsk->files = newf;
1796 error = 0;
1797out:
1798 return error;
1799}
1800
1801static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
1802{
1803 struct sighand_struct *sig;
1804
1805 if (clone_flags & CLONE_SIGHAND) {
1806 refcount_inc(&current->sighand->count);
1807 return 0;
1808 }
1809 sig = kmem_cache_alloc(sighand_cachep, GFP_KERNEL);
1810 RCU_INIT_POINTER(tsk->sighand, sig);
1811 if (!sig)
1812 return -ENOMEM;
1813
1814 refcount_set(&sig->count, 1);
1815 spin_lock_irq(&current->sighand->siglock);
1816 memcpy(sig->action, current->sighand->action, sizeof(sig->action));
1817 spin_unlock_irq(&current->sighand->siglock);
1818
1819 /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
1820 if (clone_flags & CLONE_CLEAR_SIGHAND)
1821 flush_signal_handlers(tsk, 0);
1822
1823 return 0;
1824}
1825
1826void __cleanup_sighand(struct sighand_struct *sighand)
1827{
1828 if (refcount_dec_and_test(&sighand->count)) {
1829 signalfd_cleanup(sighand);
1830 /*
1831 * sighand_cachep is SLAB_TYPESAFE_BY_RCU so we can free it
1832 * without an RCU grace period, see __lock_task_sighand().
1833 */
1834 kmem_cache_free(sighand_cachep, sighand);
1835 }
1836}
1837
1838/*
1839 * Initialize POSIX timer handling for a thread group.
1840 */
1841static void posix_cpu_timers_init_group(struct signal_struct *sig)
1842{
1843 struct posix_cputimers *pct = &sig->posix_cputimers;
1844 unsigned long cpu_limit;
1845
1846 cpu_limit = READ_ONCE(sig->rlim[RLIMIT_CPU].rlim_cur);
1847 posix_cputimers_group_init(pct, cpu_limit);
1848}
1849
1850static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
1851{
1852 struct signal_struct *sig;
1853
1854 if (clone_flags & CLONE_THREAD)
1855 return 0;
1856
1857 sig = kmem_cache_zalloc(signal_cachep, GFP_KERNEL);
1858 tsk->signal = sig;
1859 if (!sig)
1860 return -ENOMEM;
1861
1862 sig->nr_threads = 1;
1863 sig->quick_threads = 1;
1864 atomic_set(&sig->live, 1);
1865 refcount_set(&sig->sigcnt, 1);
1866
1867 /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */
1868 sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node);
1869 tsk->thread_node = (struct list_head)LIST_HEAD_INIT(sig->thread_head);
1870
1871 init_waitqueue_head(&sig->wait_chldexit);
1872 sig->curr_target = tsk;
1873 init_sigpending(&sig->shared_pending);
1874 INIT_HLIST_HEAD(&sig->multiprocess);
1875 seqlock_init(&sig->stats_lock);
1876 prev_cputime_init(&sig->prev_cputime);
1877
1878#ifdef CONFIG_POSIX_TIMERS
1879 INIT_LIST_HEAD(&sig->posix_timers);
1880 hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1881 sig->real_timer.function = it_real_fn;
1882#endif
1883
1884 task_lock(current->group_leader);
1885 memcpy(sig->rlim, current->signal->rlim, sizeof sig->rlim);
1886 task_unlock(current->group_leader);
1887
1888 posix_cpu_timers_init_group(sig);
1889
1890 tty_audit_fork(sig);
1891 sched_autogroup_fork(sig);
1892
1893 sig->oom_score_adj = current->signal->oom_score_adj;
1894 sig->oom_score_adj_min = current->signal->oom_score_adj_min;
1895
1896 mutex_init(&sig->cred_guard_mutex);
1897 init_rwsem(&sig->exec_update_lock);
1898
1899 return 0;
1900}
1901
1902static void copy_seccomp(struct task_struct *p)
1903{
1904#ifdef CONFIG_SECCOMP
1905 /*
1906 * Must be called with sighand->lock held, which is common to
1907 * all threads in the group. Holding cred_guard_mutex is not
1908 * needed because this new task is not yet running and cannot
1909 * be racing exec.
1910 */
1911 assert_spin_locked(&current->sighand->siglock);
1912
1913 /* Ref-count the new filter user, and assign it. */
1914 get_seccomp_filter(current);
1915 p->seccomp = current->seccomp;
1916
1917 /*
1918 * Explicitly enable no_new_privs here in case it got set
1919 * between the task_struct being duplicated and holding the
1920 * sighand lock. The seccomp state and nnp must be in sync.
1921 */
1922 if (task_no_new_privs(current))
1923 task_set_no_new_privs(p);
1924
1925 /*
1926 * If the parent gained a seccomp mode after copying thread
1927 * flags and between before we held the sighand lock, we have
1928 * to manually enable the seccomp thread flag here.
1929 */
1930 if (p->seccomp.mode != SECCOMP_MODE_DISABLED)
1931 set_task_syscall_work(p, SECCOMP);
1932#endif
1933}
1934
1935SYSCALL_DEFINE1(set_tid_address, int __user *, tidptr)
1936{
1937 current->clear_child_tid = tidptr;
1938
1939 return task_pid_vnr(current);
1940}
1941
1942static void rt_mutex_init_task(struct task_struct *p)
1943{
1944 raw_spin_lock_init(&p->pi_lock);
1945#ifdef CONFIG_RT_MUTEXES
1946 p->pi_waiters = RB_ROOT_CACHED;
1947 p->pi_top_task = NULL;
1948 p->pi_blocked_on = NULL;
1949#endif
1950}
1951
1952static inline void init_task_pid_links(struct task_struct *task)
1953{
1954 enum pid_type type;
1955
1956 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type)
1957 INIT_HLIST_NODE(&task->pid_links[type]);
1958}
1959
1960static inline void
1961init_task_pid(struct task_struct *task, enum pid_type type, struct pid *pid)
1962{
1963 if (type == PIDTYPE_PID)
1964 task->thread_pid = pid;
1965 else
1966 task->signal->pids[type] = pid;
1967}
1968
1969static inline void rcu_copy_process(struct task_struct *p)
1970{
1971#ifdef CONFIG_PREEMPT_RCU
1972 p->rcu_read_lock_nesting = 0;
1973 p->rcu_read_unlock_special.s = 0;
1974 p->rcu_blocked_node = NULL;
1975 INIT_LIST_HEAD(&p->rcu_node_entry);
1976#endif /* #ifdef CONFIG_PREEMPT_RCU */
1977#ifdef CONFIG_TASKS_RCU
1978 p->rcu_tasks_holdout = false;
1979 INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
1980 p->rcu_tasks_idle_cpu = -1;
1981 INIT_LIST_HEAD(&p->rcu_tasks_exit_list);
1982#endif /* #ifdef CONFIG_TASKS_RCU */
1983#ifdef CONFIG_TASKS_TRACE_RCU
1984 p->trc_reader_nesting = 0;
1985 p->trc_reader_special.s = 0;
1986 INIT_LIST_HEAD(&p->trc_holdout_list);
1987 INIT_LIST_HEAD(&p->trc_blkd_node);
1988#endif /* #ifdef CONFIG_TASKS_TRACE_RCU */
1989}
1990
1991/**
1992 * __pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
1993 * @pid: the struct pid for which to create a pidfd
1994 * @flags: flags of the new @pidfd
1995 * @ret: Where to return the file for the pidfd.
1996 *
1997 * Allocate a new file that stashes @pid and reserve a new pidfd number in the
1998 * caller's file descriptor table. The pidfd is reserved but not installed yet.
1999 *
2000 * The helper doesn't perform checks on @pid which makes it useful for pidfds
2001 * created via CLONE_PIDFD where @pid has no task attached when the pidfd and
2002 * pidfd file are prepared.
2003 *
2004 * If this function returns successfully the caller is responsible to either
2005 * call fd_install() passing the returned pidfd and pidfd file as arguments in
2006 * order to install the pidfd into its file descriptor table or they must use
2007 * put_unused_fd() and fput() on the returned pidfd and pidfd file
2008 * respectively.
2009 *
2010 * This function is useful when a pidfd must already be reserved but there
2011 * might still be points of failure afterwards and the caller wants to ensure
2012 * that no pidfd is leaked into its file descriptor table.
2013 *
2014 * Return: On success, a reserved pidfd is returned from the function and a new
2015 * pidfd file is returned in the last argument to the function. On
2016 * error, a negative error code is returned from the function and the
2017 * last argument remains unchanged.
2018 */
2019static int __pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
2020{
2021 int pidfd;
2022 struct file *pidfd_file;
2023
2024 pidfd = get_unused_fd_flags(O_CLOEXEC);
2025 if (pidfd < 0)
2026 return pidfd;
2027
2028 pidfd_file = pidfs_alloc_file(pid, flags | O_RDWR);
2029 if (IS_ERR(pidfd_file)) {
2030 put_unused_fd(pidfd);
2031 return PTR_ERR(pidfd_file);
2032 }
2033 /*
2034 * anon_inode_getfile() ignores everything outside of the
2035 * O_ACCMODE | O_NONBLOCK mask, set PIDFD_THREAD manually.
2036 */
2037 pidfd_file->f_flags |= (flags & PIDFD_THREAD);
2038 *ret = pidfd_file;
2039 return pidfd;
2040}
2041
2042/**
2043 * pidfd_prepare - allocate a new pidfd_file and reserve a pidfd
2044 * @pid: the struct pid for which to create a pidfd
2045 * @flags: flags of the new @pidfd
2046 * @ret: Where to return the pidfd.
2047 *
2048 * Allocate a new file that stashes @pid and reserve a new pidfd number in the
2049 * caller's file descriptor table. The pidfd is reserved but not installed yet.
2050 *
2051 * The helper verifies that @pid is still in use, without PIDFD_THREAD the
2052 * task identified by @pid must be a thread-group leader.
2053 *
2054 * If this function returns successfully the caller is responsible to either
2055 * call fd_install() passing the returned pidfd and pidfd file as arguments in
2056 * order to install the pidfd into its file descriptor table or they must use
2057 * put_unused_fd() and fput() on the returned pidfd and pidfd file
2058 * respectively.
2059 *
2060 * This function is useful when a pidfd must already be reserved but there
2061 * might still be points of failure afterwards and the caller wants to ensure
2062 * that no pidfd is leaked into its file descriptor table.
2063 *
2064 * Return: On success, a reserved pidfd is returned from the function and a new
2065 * pidfd file is returned in the last argument to the function. On
2066 * error, a negative error code is returned from the function and the
2067 * last argument remains unchanged.
2068 */
2069int pidfd_prepare(struct pid *pid, unsigned int flags, struct file **ret)
2070{
2071 bool thread = flags & PIDFD_THREAD;
2072
2073 if (!pid || !pid_has_task(pid, thread ? PIDTYPE_PID : PIDTYPE_TGID))
2074 return -EINVAL;
2075
2076 return __pidfd_prepare(pid, flags, ret);
2077}
2078
2079static void __delayed_free_task(struct rcu_head *rhp)
2080{
2081 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
2082
2083 free_task(tsk);
2084}
2085
2086static __always_inline void delayed_free_task(struct task_struct *tsk)
2087{
2088 if (IS_ENABLED(CONFIG_MEMCG))
2089 call_rcu(&tsk->rcu, __delayed_free_task);
2090 else
2091 free_task(tsk);
2092}
2093
2094static void copy_oom_score_adj(u64 clone_flags, struct task_struct *tsk)
2095{
2096 /* Skip if kernel thread */
2097 if (!tsk->mm)
2098 return;
2099
2100 /* Skip if spawning a thread or using vfork */
2101 if ((clone_flags & (CLONE_VM | CLONE_THREAD | CLONE_VFORK)) != CLONE_VM)
2102 return;
2103
2104 /* We need to synchronize with __set_oom_adj */
2105 mutex_lock(&oom_adj_mutex);
2106 set_bit(MMF_MULTIPROCESS, &tsk->mm->flags);
2107 /* Update the values in case they were changed after copy_signal */
2108 tsk->signal->oom_score_adj = current->signal->oom_score_adj;
2109 tsk->signal->oom_score_adj_min = current->signal->oom_score_adj_min;
2110 mutex_unlock(&oom_adj_mutex);
2111}
2112
2113#ifdef CONFIG_RV
2114static void rv_task_fork(struct task_struct *p)
2115{
2116 int i;
2117
2118 for (i = 0; i < RV_PER_TASK_MONITORS; i++)
2119 p->rv[i].da_mon.monitoring = false;
2120}
2121#else
2122#define rv_task_fork(p) do {} while (0)
2123#endif
2124
2125/*
2126 * This creates a new process as a copy of the old one,
2127 * but does not actually start it yet.
2128 *
2129 * It copies the registers, and all the appropriate
2130 * parts of the process environment (as per the clone
2131 * flags). The actual kick-off is left to the caller.
2132 */
2133__latent_entropy struct task_struct *copy_process(
2134 struct pid *pid,
2135 int trace,
2136 int node,
2137 struct kernel_clone_args *args)
2138{
2139 int pidfd = -1, retval;
2140 struct task_struct *p;
2141 struct multiprocess_signals delayed;
2142 struct file *pidfile = NULL;
2143 const u64 clone_flags = args->flags;
2144 struct nsproxy *nsp = current->nsproxy;
2145
2146 /*
2147 * Don't allow sharing the root directory with processes in a different
2148 * namespace
2149 */
2150 if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
2151 return ERR_PTR(-EINVAL);
2152
2153 if ((clone_flags & (CLONE_NEWUSER|CLONE_FS)) == (CLONE_NEWUSER|CLONE_FS))
2154 return ERR_PTR(-EINVAL);
2155
2156 /*
2157 * Thread groups must share signals as well, and detached threads
2158 * can only be started up within the thread group.
2159 */
2160 if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
2161 return ERR_PTR(-EINVAL);
2162
2163 /*
2164 * Shared signal handlers imply shared VM. By way of the above,
2165 * thread groups also imply shared VM. Blocking this case allows
2166 * for various simplifications in other code.
2167 */
2168 if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
2169 return ERR_PTR(-EINVAL);
2170
2171 /*
2172 * Siblings of global init remain as zombies on exit since they are
2173 * not reaped by their parent (swapper). To solve this and to avoid
2174 * multi-rooted process trees, prevent global and container-inits
2175 * from creating siblings.
2176 */
2177 if ((clone_flags & CLONE_PARENT) &&
2178 current->signal->flags & SIGNAL_UNKILLABLE)
2179 return ERR_PTR(-EINVAL);
2180
2181 /*
2182 * If the new process will be in a different pid or user namespace
2183 * do not allow it to share a thread group with the forking task.
2184 */
2185 if (clone_flags & CLONE_THREAD) {
2186 if ((clone_flags & (CLONE_NEWUSER | CLONE_NEWPID)) ||
2187 (task_active_pid_ns(current) != nsp->pid_ns_for_children))
2188 return ERR_PTR(-EINVAL);
2189 }
2190
2191 if (clone_flags & CLONE_PIDFD) {
2192 /*
2193 * - CLONE_DETACHED is blocked so that we can potentially
2194 * reuse it later for CLONE_PIDFD.
2195 */
2196 if (clone_flags & CLONE_DETACHED)
2197 return ERR_PTR(-EINVAL);
2198 }
2199
2200 /*
2201 * Force any signals received before this point to be delivered
2202 * before the fork happens. Collect up signals sent to multiple
2203 * processes that happen during the fork and delay them so that
2204 * they appear to happen after the fork.
2205 */
2206 sigemptyset(&delayed.signal);
2207 INIT_HLIST_NODE(&delayed.node);
2208
2209 spin_lock_irq(&current->sighand->siglock);
2210 if (!(clone_flags & CLONE_THREAD))
2211 hlist_add_head(&delayed.node, &current->signal->multiprocess);
2212 recalc_sigpending();
2213 spin_unlock_irq(&current->sighand->siglock);
2214 retval = -ERESTARTNOINTR;
2215 if (task_sigpending(current))
2216 goto fork_out;
2217
2218 retval = -ENOMEM;
2219 p = dup_task_struct(current, node);
2220 if (!p)
2221 goto fork_out;
2222 p->flags &= ~PF_KTHREAD;
2223 if (args->kthread)
2224 p->flags |= PF_KTHREAD;
2225 if (args->user_worker) {
2226 /*
2227 * Mark us a user worker, and block any signal that isn't
2228 * fatal or STOP
2229 */
2230 p->flags |= PF_USER_WORKER;
2231 siginitsetinv(&p->blocked, sigmask(SIGKILL)|sigmask(SIGSTOP));
2232 }
2233 if (args->io_thread)
2234 p->flags |= PF_IO_WORKER;
2235
2236 if (args->name)
2237 strscpy_pad(p->comm, args->name, sizeof(p->comm));
2238
2239 p->set_child_tid = (clone_flags & CLONE_CHILD_SETTID) ? args->child_tid : NULL;
2240 /*
2241 * Clear TID on mm_release()?
2242 */
2243 p->clear_child_tid = (clone_flags & CLONE_CHILD_CLEARTID) ? args->child_tid : NULL;
2244
2245 ftrace_graph_init_task(p);
2246
2247 rt_mutex_init_task(p);
2248
2249 lockdep_assert_irqs_enabled();
2250#ifdef CONFIG_PROVE_LOCKING
2251 DEBUG_LOCKS_WARN_ON(!p->softirqs_enabled);
2252#endif
2253 retval = copy_creds(p, clone_flags);
2254 if (retval < 0)
2255 goto bad_fork_free;
2256
2257 retval = -EAGAIN;
2258 if (is_rlimit_overlimit(task_ucounts(p), UCOUNT_RLIMIT_NPROC, rlimit(RLIMIT_NPROC))) {
2259 if (p->real_cred->user != INIT_USER &&
2260 !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN))
2261 goto bad_fork_cleanup_count;
2262 }
2263 current->flags &= ~PF_NPROC_EXCEEDED;
2264
2265 /*
2266 * If multiple threads are within copy_process(), then this check
2267 * triggers too late. This doesn't hurt, the check is only there
2268 * to stop root fork bombs.
2269 */
2270 retval = -EAGAIN;
2271 if (data_race(nr_threads >= max_threads))
2272 goto bad_fork_cleanup_count;
2273
2274 delayacct_tsk_init(p); /* Must remain after dup_task_struct() */
2275 p->flags &= ~(PF_SUPERPRIV | PF_WQ_WORKER | PF_IDLE | PF_NO_SETAFFINITY);
2276 p->flags |= PF_FORKNOEXEC;
2277 INIT_LIST_HEAD(&p->children);
2278 INIT_LIST_HEAD(&p->sibling);
2279 rcu_copy_process(p);
2280 p->vfork_done = NULL;
2281 spin_lock_init(&p->alloc_lock);
2282
2283 init_sigpending(&p->pending);
2284
2285 p->utime = p->stime = p->gtime = 0;
2286#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
2287 p->utimescaled = p->stimescaled = 0;
2288#endif
2289 prev_cputime_init(&p->prev_cputime);
2290
2291#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
2292 seqcount_init(&p->vtime.seqcount);
2293 p->vtime.starttime = 0;
2294 p->vtime.state = VTIME_INACTIVE;
2295#endif
2296
2297#ifdef CONFIG_IO_URING
2298 p->io_uring = NULL;
2299#endif
2300
2301 p->default_timer_slack_ns = current->timer_slack_ns;
2302
2303#ifdef CONFIG_PSI
2304 p->psi_flags = 0;
2305#endif
2306
2307 task_io_accounting_init(&p->ioac);
2308 acct_clear_integrals(p);
2309
2310 posix_cputimers_init(&p->posix_cputimers);
2311
2312 p->io_context = NULL;
2313 audit_set_context(p, NULL);
2314 cgroup_fork(p);
2315 if (args->kthread) {
2316 if (!set_kthread_struct(p))
2317 goto bad_fork_cleanup_delayacct;
2318 }
2319#ifdef CONFIG_NUMA
2320 p->mempolicy = mpol_dup(p->mempolicy);
2321 if (IS_ERR(p->mempolicy)) {
2322 retval = PTR_ERR(p->mempolicy);
2323 p->mempolicy = NULL;
2324 goto bad_fork_cleanup_delayacct;
2325 }
2326#endif
2327#ifdef CONFIG_CPUSETS
2328 p->cpuset_mem_spread_rotor = NUMA_NO_NODE;
2329 p->cpuset_slab_spread_rotor = NUMA_NO_NODE;
2330 seqcount_spinlock_init(&p->mems_allowed_seq, &p->alloc_lock);
2331#endif
2332#ifdef CONFIG_TRACE_IRQFLAGS
2333 memset(&p->irqtrace, 0, sizeof(p->irqtrace));
2334 p->irqtrace.hardirq_disable_ip = _THIS_IP_;
2335 p->irqtrace.softirq_enable_ip = _THIS_IP_;
2336 p->softirqs_enabled = 1;
2337 p->softirq_context = 0;
2338#endif
2339
2340 p->pagefault_disabled = 0;
2341
2342#ifdef CONFIG_LOCKDEP
2343 lockdep_init_task(p);
2344#endif
2345
2346#ifdef CONFIG_DEBUG_MUTEXES
2347 p->blocked_on = NULL; /* not blocked yet */
2348#endif
2349#ifdef CONFIG_BCACHE
2350 p->sequential_io = 0;
2351 p->sequential_io_avg = 0;
2352#endif
2353#ifdef CONFIG_BPF_SYSCALL
2354 RCU_INIT_POINTER(p->bpf_storage, NULL);
2355 p->bpf_ctx = NULL;
2356#endif
2357
2358 /* Perform scheduler related setup. Assign this task to a CPU. */
2359 retval = sched_fork(clone_flags, p);
2360 if (retval)
2361 goto bad_fork_cleanup_policy;
2362
2363 retval = perf_event_init_task(p, clone_flags);
2364 if (retval)
2365 goto bad_fork_cleanup_policy;
2366 retval = audit_alloc(p);
2367 if (retval)
2368 goto bad_fork_cleanup_perf;
2369 /* copy all the process information */
2370 shm_init_task(p);
2371 retval = security_task_alloc(p, clone_flags);
2372 if (retval)
2373 goto bad_fork_cleanup_audit;
2374 retval = copy_semundo(clone_flags, p);
2375 if (retval)
2376 goto bad_fork_cleanup_security;
2377 retval = copy_files(clone_flags, p, args->no_files);
2378 if (retval)
2379 goto bad_fork_cleanup_semundo;
2380 retval = copy_fs(clone_flags, p);
2381 if (retval)
2382 goto bad_fork_cleanup_files;
2383 retval = copy_sighand(clone_flags, p);
2384 if (retval)
2385 goto bad_fork_cleanup_fs;
2386 retval = copy_signal(clone_flags, p);
2387 if (retval)
2388 goto bad_fork_cleanup_sighand;
2389 retval = copy_mm(clone_flags, p);
2390 if (retval)
2391 goto bad_fork_cleanup_signal;
2392 retval = copy_namespaces(clone_flags, p);
2393 if (retval)
2394 goto bad_fork_cleanup_mm;
2395 retval = copy_io(clone_flags, p);
2396 if (retval)
2397 goto bad_fork_cleanup_namespaces;
2398 retval = copy_thread(p, args);
2399 if (retval)
2400 goto bad_fork_cleanup_io;
2401
2402 stackleak_task_init(p);
2403
2404 if (pid != &init_struct_pid) {
2405 pid = alloc_pid(p->nsproxy->pid_ns_for_children, args->set_tid,
2406 args->set_tid_size);
2407 if (IS_ERR(pid)) {
2408 retval = PTR_ERR(pid);
2409 goto bad_fork_cleanup_thread;
2410 }
2411 }
2412
2413 /*
2414 * This has to happen after we've potentially unshared the file
2415 * descriptor table (so that the pidfd doesn't leak into the child
2416 * if the fd table isn't shared).
2417 */
2418 if (clone_flags & CLONE_PIDFD) {
2419 int flags = (clone_flags & CLONE_THREAD) ? PIDFD_THREAD : 0;
2420
2421 /* Note that no task has been attached to @pid yet. */
2422 retval = __pidfd_prepare(pid, flags, &pidfile);
2423 if (retval < 0)
2424 goto bad_fork_free_pid;
2425 pidfd = retval;
2426
2427 retval = put_user(pidfd, args->pidfd);
2428 if (retval)
2429 goto bad_fork_put_pidfd;
2430 }
2431
2432#ifdef CONFIG_BLOCK
2433 p->plug = NULL;
2434#endif
2435 futex_init_task(p);
2436
2437 /*
2438 * sigaltstack should be cleared when sharing the same VM
2439 */
2440 if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
2441 sas_ss_reset(p);
2442
2443 /*
2444 * Syscall tracing and stepping should be turned off in the
2445 * child regardless of CLONE_PTRACE.
2446 */
2447 user_disable_single_step(p);
2448 clear_task_syscall_work(p, SYSCALL_TRACE);
2449#if defined(CONFIG_GENERIC_ENTRY) || defined(TIF_SYSCALL_EMU)
2450 clear_task_syscall_work(p, SYSCALL_EMU);
2451#endif
2452 clear_tsk_latency_tracing(p);
2453
2454 /* ok, now we should be set up.. */
2455 p->pid = pid_nr(pid);
2456 if (clone_flags & CLONE_THREAD) {
2457 p->group_leader = current->group_leader;
2458 p->tgid = current->tgid;
2459 } else {
2460 p->group_leader = p;
2461 p->tgid = p->pid;
2462 }
2463
2464 p->nr_dirtied = 0;
2465 p->nr_dirtied_pause = 128 >> (PAGE_SHIFT - 10);
2466 p->dirty_paused_when = 0;
2467
2468 p->pdeath_signal = 0;
2469 p->task_works = NULL;
2470 clear_posix_cputimers_work(p);
2471
2472#ifdef CONFIG_KRETPROBES
2473 p->kretprobe_instances.first = NULL;
2474#endif
2475#ifdef CONFIG_RETHOOK
2476 p->rethooks.first = NULL;
2477#endif
2478
2479 /*
2480 * Ensure that the cgroup subsystem policies allow the new process to be
2481 * forked. It should be noted that the new process's css_set can be changed
2482 * between here and cgroup_post_fork() if an organisation operation is in
2483 * progress.
2484 */
2485 retval = cgroup_can_fork(p, args);
2486 if (retval)
2487 goto bad_fork_put_pidfd;
2488
2489 /*
2490 * Now that the cgroups are pinned, re-clone the parent cgroup and put
2491 * the new task on the correct runqueue. All this *before* the task
2492 * becomes visible.
2493 *
2494 * This isn't part of ->can_fork() because while the re-cloning is
2495 * cgroup specific, it unconditionally needs to place the task on a
2496 * runqueue.
2497 */
2498 sched_cgroup_fork(p, args);
2499
2500 /*
2501 * From this point on we must avoid any synchronous user-space
2502 * communication until we take the tasklist-lock. In particular, we do
2503 * not want user-space to be able to predict the process start-time by
2504 * stalling fork(2) after we recorded the start_time but before it is
2505 * visible to the system.
2506 */
2507
2508 p->start_time = ktime_get_ns();
2509 p->start_boottime = ktime_get_boottime_ns();
2510
2511 /*
2512 * Make it visible to the rest of the system, but dont wake it up yet.
2513 * Need tasklist lock for parent etc handling!
2514 */
2515 write_lock_irq(&tasklist_lock);
2516
2517 /* CLONE_PARENT re-uses the old parent */
2518 if (clone_flags & (CLONE_PARENT|CLONE_THREAD)) {
2519 p->real_parent = current->real_parent;
2520 p->parent_exec_id = current->parent_exec_id;
2521 if (clone_flags & CLONE_THREAD)
2522 p->exit_signal = -1;
2523 else
2524 p->exit_signal = current->group_leader->exit_signal;
2525 } else {
2526 p->real_parent = current;
2527 p->parent_exec_id = current->self_exec_id;
2528 p->exit_signal = args->exit_signal;
2529 }
2530
2531 klp_copy_process(p);
2532
2533 sched_core_fork(p);
2534
2535 spin_lock(&current->sighand->siglock);
2536
2537 rv_task_fork(p);
2538
2539 rseq_fork(p, clone_flags);
2540
2541 /* Don't start children in a dying pid namespace */
2542 if (unlikely(!(ns_of_pid(pid)->pid_allocated & PIDNS_ADDING))) {
2543 retval = -ENOMEM;
2544 goto bad_fork_cancel_cgroup;
2545 }
2546
2547 /* Let kill terminate clone/fork in the middle */
2548 if (fatal_signal_pending(current)) {
2549 retval = -EINTR;
2550 goto bad_fork_cancel_cgroup;
2551 }
2552
2553 /* No more failure paths after this point. */
2554
2555 /*
2556 * Copy seccomp details explicitly here, in case they were changed
2557 * before holding sighand lock.
2558 */
2559 copy_seccomp(p);
2560
2561 init_task_pid_links(p);
2562 if (likely(p->pid)) {
2563 ptrace_init_task(p, (clone_flags & CLONE_PTRACE) || trace);
2564
2565 init_task_pid(p, PIDTYPE_PID, pid);
2566 if (thread_group_leader(p)) {
2567 init_task_pid(p, PIDTYPE_TGID, pid);
2568 init_task_pid(p, PIDTYPE_PGID, task_pgrp(current));
2569 init_task_pid(p, PIDTYPE_SID, task_session(current));
2570
2571 if (is_child_reaper(pid)) {
2572 ns_of_pid(pid)->child_reaper = p;
2573 p->signal->flags |= SIGNAL_UNKILLABLE;
2574 }
2575 p->signal->shared_pending.signal = delayed.signal;
2576 p->signal->tty = tty_kref_get(current->signal->tty);
2577 /*
2578 * Inherit has_child_subreaper flag under the same
2579 * tasklist_lock with adding child to the process tree
2580 * for propagate_has_child_subreaper optimization.
2581 */
2582 p->signal->has_child_subreaper = p->real_parent->signal->has_child_subreaper ||
2583 p->real_parent->signal->is_child_subreaper;
2584 list_add_tail(&p->sibling, &p->real_parent->children);
2585 list_add_tail_rcu(&p->tasks, &init_task.tasks);
2586 attach_pid(p, PIDTYPE_TGID);
2587 attach_pid(p, PIDTYPE_PGID);
2588 attach_pid(p, PIDTYPE_SID);
2589 __this_cpu_inc(process_counts);
2590 } else {
2591 current->signal->nr_threads++;
2592 current->signal->quick_threads++;
2593 atomic_inc(&current->signal->live);
2594 refcount_inc(&current->signal->sigcnt);
2595 task_join_group_stop(p);
2596 list_add_tail_rcu(&p->thread_node,
2597 &p->signal->thread_head);
2598 }
2599 attach_pid(p, PIDTYPE_PID);
2600 nr_threads++;
2601 }
2602 total_forks++;
2603 hlist_del_init(&delayed.node);
2604 spin_unlock(&current->sighand->siglock);
2605 syscall_tracepoint_update(p);
2606 write_unlock_irq(&tasklist_lock);
2607
2608 if (pidfile)
2609 fd_install(pidfd, pidfile);
2610
2611 proc_fork_connector(p);
2612 sched_post_fork(p);
2613 cgroup_post_fork(p, args);
2614 perf_event_fork(p);
2615
2616 trace_task_newtask(p, clone_flags);
2617 uprobe_copy_process(p, clone_flags);
2618 user_events_fork(p, clone_flags);
2619
2620 copy_oom_score_adj(clone_flags, p);
2621
2622 return p;
2623
2624bad_fork_cancel_cgroup:
2625 sched_core_free(p);
2626 spin_unlock(&current->sighand->siglock);
2627 write_unlock_irq(&tasklist_lock);
2628 cgroup_cancel_fork(p, args);
2629bad_fork_put_pidfd:
2630 if (clone_flags & CLONE_PIDFD) {
2631 fput(pidfile);
2632 put_unused_fd(pidfd);
2633 }
2634bad_fork_free_pid:
2635 if (pid != &init_struct_pid)
2636 free_pid(pid);
2637bad_fork_cleanup_thread:
2638 exit_thread(p);
2639bad_fork_cleanup_io:
2640 if (p->io_context)
2641 exit_io_context(p);
2642bad_fork_cleanup_namespaces:
2643 exit_task_namespaces(p);
2644bad_fork_cleanup_mm:
2645 if (p->mm) {
2646 mm_clear_owner(p->mm, p);
2647 mmput(p->mm);
2648 }
2649bad_fork_cleanup_signal:
2650 if (!(clone_flags & CLONE_THREAD))
2651 free_signal_struct(p->signal);
2652bad_fork_cleanup_sighand:
2653 __cleanup_sighand(p->sighand);
2654bad_fork_cleanup_fs:
2655 exit_fs(p); /* blocking */
2656bad_fork_cleanup_files:
2657 exit_files(p); /* blocking */
2658bad_fork_cleanup_semundo:
2659 exit_sem(p);
2660bad_fork_cleanup_security:
2661 security_task_free(p);
2662bad_fork_cleanup_audit:
2663 audit_free(p);
2664bad_fork_cleanup_perf:
2665 perf_event_free_task(p);
2666bad_fork_cleanup_policy:
2667 lockdep_free_task(p);
2668#ifdef CONFIG_NUMA
2669 mpol_put(p->mempolicy);
2670#endif
2671bad_fork_cleanup_delayacct:
2672 delayacct_tsk_free(p);
2673bad_fork_cleanup_count:
2674 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
2675 exit_creds(p);
2676bad_fork_free:
2677 WRITE_ONCE(p->__state, TASK_DEAD);
2678 exit_task_stack_account(p);
2679 put_task_stack(p);
2680 delayed_free_task(p);
2681fork_out:
2682 spin_lock_irq(&current->sighand->siglock);
2683 hlist_del_init(&delayed.node);
2684 spin_unlock_irq(&current->sighand->siglock);
2685 return ERR_PTR(retval);
2686}
2687
2688static inline void init_idle_pids(struct task_struct *idle)
2689{
2690 enum pid_type type;
2691
2692 for (type = PIDTYPE_PID; type < PIDTYPE_MAX; ++type) {
2693 INIT_HLIST_NODE(&idle->pid_links[type]); /* not really needed */
2694 init_task_pid(idle, type, &init_struct_pid);
2695 }
2696}
2697
2698static int idle_dummy(void *dummy)
2699{
2700 /* This function is never called */
2701 return 0;
2702}
2703
2704struct task_struct * __init fork_idle(int cpu)
2705{
2706 struct task_struct *task;
2707 struct kernel_clone_args args = {
2708 .flags = CLONE_VM,
2709 .fn = &idle_dummy,
2710 .fn_arg = NULL,
2711 .kthread = 1,
2712 .idle = 1,
2713 };
2714
2715 task = copy_process(&init_struct_pid, 0, cpu_to_node(cpu), &args);
2716 if (!IS_ERR(task)) {
2717 init_idle_pids(task);
2718 init_idle(task, cpu);
2719 }
2720
2721 return task;
2722}
2723
2724/*
2725 * This is like kernel_clone(), but shaved down and tailored to just
2726 * creating io_uring workers. It returns a created task, or an error pointer.
2727 * The returned task is inactive, and the caller must fire it up through
2728 * wake_up_new_task(p). All signals are blocked in the created task.
2729 */
2730struct task_struct *create_io_thread(int (*fn)(void *), void *arg, int node)
2731{
2732 unsigned long flags = CLONE_FS|CLONE_FILES|CLONE_SIGHAND|CLONE_THREAD|
2733 CLONE_IO;
2734 struct kernel_clone_args args = {
2735 .flags = ((lower_32_bits(flags) | CLONE_VM |
2736 CLONE_UNTRACED) & ~CSIGNAL),
2737 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2738 .fn = fn,
2739 .fn_arg = arg,
2740 .io_thread = 1,
2741 .user_worker = 1,
2742 };
2743
2744 return copy_process(NULL, 0, node, &args);
2745}
2746
2747/*
2748 * Ok, this is the main fork-routine.
2749 *
2750 * It copies the process, and if successful kick-starts
2751 * it and waits for it to finish using the VM if required.
2752 *
2753 * args->exit_signal is expected to be checked for sanity by the caller.
2754 */
2755pid_t kernel_clone(struct kernel_clone_args *args)
2756{
2757 u64 clone_flags = args->flags;
2758 struct completion vfork;
2759 struct pid *pid;
2760 struct task_struct *p;
2761 int trace = 0;
2762 pid_t nr;
2763
2764 /*
2765 * For legacy clone() calls, CLONE_PIDFD uses the parent_tid argument
2766 * to return the pidfd. Hence, CLONE_PIDFD and CLONE_PARENT_SETTID are
2767 * mutually exclusive. With clone3() CLONE_PIDFD has grown a separate
2768 * field in struct clone_args and it still doesn't make sense to have
2769 * them both point at the same memory location. Performing this check
2770 * here has the advantage that we don't need to have a separate helper
2771 * to check for legacy clone().
2772 */
2773 if ((clone_flags & CLONE_PIDFD) &&
2774 (clone_flags & CLONE_PARENT_SETTID) &&
2775 (args->pidfd == args->parent_tid))
2776 return -EINVAL;
2777
2778 /*
2779 * Determine whether and which event to report to ptracer. When
2780 * called from kernel_thread or CLONE_UNTRACED is explicitly
2781 * requested, no event is reported; otherwise, report if the event
2782 * for the type of forking is enabled.
2783 */
2784 if (!(clone_flags & CLONE_UNTRACED)) {
2785 if (clone_flags & CLONE_VFORK)
2786 trace = PTRACE_EVENT_VFORK;
2787 else if (args->exit_signal != SIGCHLD)
2788 trace = PTRACE_EVENT_CLONE;
2789 else
2790 trace = PTRACE_EVENT_FORK;
2791
2792 if (likely(!ptrace_event_enabled(current, trace)))
2793 trace = 0;
2794 }
2795
2796 p = copy_process(NULL, trace, NUMA_NO_NODE, args);
2797 add_latent_entropy();
2798
2799 if (IS_ERR(p))
2800 return PTR_ERR(p);
2801
2802 /*
2803 * Do this prior waking up the new thread - the thread pointer
2804 * might get invalid after that point, if the thread exits quickly.
2805 */
2806 trace_sched_process_fork(current, p);
2807
2808 pid = get_task_pid(p, PIDTYPE_PID);
2809 nr = pid_vnr(pid);
2810
2811 if (clone_flags & CLONE_PARENT_SETTID)
2812 put_user(nr, args->parent_tid);
2813
2814 if (clone_flags & CLONE_VFORK) {
2815 p->vfork_done = &vfork;
2816 init_completion(&vfork);
2817 get_task_struct(p);
2818 }
2819
2820 if (IS_ENABLED(CONFIG_LRU_GEN_WALKS_MMU) && !(clone_flags & CLONE_VM)) {
2821 /* lock the task to synchronize with memcg migration */
2822 task_lock(p);
2823 lru_gen_add_mm(p->mm);
2824 task_unlock(p);
2825 }
2826
2827 wake_up_new_task(p);
2828
2829 /* forking complete and child started to run, tell ptracer */
2830 if (unlikely(trace))
2831 ptrace_event_pid(trace, pid);
2832
2833 if (clone_flags & CLONE_VFORK) {
2834 if (!wait_for_vfork_done(p, &vfork))
2835 ptrace_event_pid(PTRACE_EVENT_VFORK_DONE, pid);
2836 }
2837
2838 put_pid(pid);
2839 return nr;
2840}
2841
2842/*
2843 * Create a kernel thread.
2844 */
2845pid_t kernel_thread(int (*fn)(void *), void *arg, const char *name,
2846 unsigned long flags)
2847{
2848 struct kernel_clone_args args = {
2849 .flags = ((lower_32_bits(flags) | CLONE_VM |
2850 CLONE_UNTRACED) & ~CSIGNAL),
2851 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2852 .fn = fn,
2853 .fn_arg = arg,
2854 .name = name,
2855 .kthread = 1,
2856 };
2857
2858 return kernel_clone(&args);
2859}
2860
2861/*
2862 * Create a user mode thread.
2863 */
2864pid_t user_mode_thread(int (*fn)(void *), void *arg, unsigned long flags)
2865{
2866 struct kernel_clone_args args = {
2867 .flags = ((lower_32_bits(flags) | CLONE_VM |
2868 CLONE_UNTRACED) & ~CSIGNAL),
2869 .exit_signal = (lower_32_bits(flags) & CSIGNAL),
2870 .fn = fn,
2871 .fn_arg = arg,
2872 };
2873
2874 return kernel_clone(&args);
2875}
2876
2877#ifdef __ARCH_WANT_SYS_FORK
2878SYSCALL_DEFINE0(fork)
2879{
2880#ifdef CONFIG_MMU
2881 struct kernel_clone_args args = {
2882 .exit_signal = SIGCHLD,
2883 };
2884
2885 return kernel_clone(&args);
2886#else
2887 /* can not support in nommu mode */
2888 return -EINVAL;
2889#endif
2890}
2891#endif
2892
2893#ifdef __ARCH_WANT_SYS_VFORK
2894SYSCALL_DEFINE0(vfork)
2895{
2896 struct kernel_clone_args args = {
2897 .flags = CLONE_VFORK | CLONE_VM,
2898 .exit_signal = SIGCHLD,
2899 };
2900
2901 return kernel_clone(&args);
2902}
2903#endif
2904
2905#ifdef __ARCH_WANT_SYS_CLONE
2906#ifdef CONFIG_CLONE_BACKWARDS
2907SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2908 int __user *, parent_tidptr,
2909 unsigned long, tls,
2910 int __user *, child_tidptr)
2911#elif defined(CONFIG_CLONE_BACKWARDS2)
2912SYSCALL_DEFINE5(clone, unsigned long, newsp, unsigned long, clone_flags,
2913 int __user *, parent_tidptr,
2914 int __user *, child_tidptr,
2915 unsigned long, tls)
2916#elif defined(CONFIG_CLONE_BACKWARDS3)
2917SYSCALL_DEFINE6(clone, unsigned long, clone_flags, unsigned long, newsp,
2918 int, stack_size,
2919 int __user *, parent_tidptr,
2920 int __user *, child_tidptr,
2921 unsigned long, tls)
2922#else
2923SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
2924 int __user *, parent_tidptr,
2925 int __user *, child_tidptr,
2926 unsigned long, tls)
2927#endif
2928{
2929 struct kernel_clone_args args = {
2930 .flags = (lower_32_bits(clone_flags) & ~CSIGNAL),
2931 .pidfd = parent_tidptr,
2932 .child_tid = child_tidptr,
2933 .parent_tid = parent_tidptr,
2934 .exit_signal = (lower_32_bits(clone_flags) & CSIGNAL),
2935 .stack = newsp,
2936 .tls = tls,
2937 };
2938
2939 return kernel_clone(&args);
2940}
2941#endif
2942
2943#ifdef __ARCH_WANT_SYS_CLONE3
2944
2945noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
2946 struct clone_args __user *uargs,
2947 size_t usize)
2948{
2949 int err;
2950 struct clone_args args;
2951 pid_t *kset_tid = kargs->set_tid;
2952
2953 BUILD_BUG_ON(offsetofend(struct clone_args, tls) !=
2954 CLONE_ARGS_SIZE_VER0);
2955 BUILD_BUG_ON(offsetofend(struct clone_args, set_tid_size) !=
2956 CLONE_ARGS_SIZE_VER1);
2957 BUILD_BUG_ON(offsetofend(struct clone_args, cgroup) !=
2958 CLONE_ARGS_SIZE_VER2);
2959 BUILD_BUG_ON(sizeof(struct clone_args) != CLONE_ARGS_SIZE_VER2);
2960
2961 if (unlikely(usize > PAGE_SIZE))
2962 return -E2BIG;
2963 if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
2964 return -EINVAL;
2965
2966 err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
2967 if (err)
2968 return err;
2969
2970 if (unlikely(args.set_tid_size > MAX_PID_NS_LEVEL))
2971 return -EINVAL;
2972
2973 if (unlikely(!args.set_tid && args.set_tid_size > 0))
2974 return -EINVAL;
2975
2976 if (unlikely(args.set_tid && args.set_tid_size == 0))
2977 return -EINVAL;
2978
2979 /*
2980 * Verify that higher 32bits of exit_signal are unset and that
2981 * it is a valid signal
2982 */
2983 if (unlikely((args.exit_signal & ~((u64)CSIGNAL)) ||
2984 !valid_signal(args.exit_signal)))
2985 return -EINVAL;
2986
2987 if ((args.flags & CLONE_INTO_CGROUP) &&
2988 (args.cgroup > INT_MAX || usize < CLONE_ARGS_SIZE_VER2))
2989 return -EINVAL;
2990
2991 *kargs = (struct kernel_clone_args){
2992 .flags = args.flags,
2993 .pidfd = u64_to_user_ptr(args.pidfd),
2994 .child_tid = u64_to_user_ptr(args.child_tid),
2995 .parent_tid = u64_to_user_ptr(args.parent_tid),
2996 .exit_signal = args.exit_signal,
2997 .stack = args.stack,
2998 .stack_size = args.stack_size,
2999 .tls = args.tls,
3000 .set_tid_size = args.set_tid_size,
3001 .cgroup = args.cgroup,
3002 };
3003
3004 if (args.set_tid &&
3005 copy_from_user(kset_tid, u64_to_user_ptr(args.set_tid),
3006 (kargs->set_tid_size * sizeof(pid_t))))
3007 return -EFAULT;
3008
3009 kargs->set_tid = kset_tid;
3010
3011 return 0;
3012}
3013
3014/**
3015 * clone3_stack_valid - check and prepare stack
3016 * @kargs: kernel clone args
3017 *
3018 * Verify that the stack arguments userspace gave us are sane.
3019 * In addition, set the stack direction for userspace since it's easy for us to
3020 * determine.
3021 */
3022static inline bool clone3_stack_valid(struct kernel_clone_args *kargs)
3023{
3024 if (kargs->stack == 0) {
3025 if (kargs->stack_size > 0)
3026 return false;
3027 } else {
3028 if (kargs->stack_size == 0)
3029 return false;
3030
3031 if (!access_ok((void __user *)kargs->stack, kargs->stack_size))
3032 return false;
3033
3034#if !defined(CONFIG_STACK_GROWSUP)
3035 kargs->stack += kargs->stack_size;
3036#endif
3037 }
3038
3039 return true;
3040}
3041
3042static bool clone3_args_valid(struct kernel_clone_args *kargs)
3043{
3044 /* Verify that no unknown flags are passed along. */
3045 if (kargs->flags &
3046 ~(CLONE_LEGACY_FLAGS | CLONE_CLEAR_SIGHAND | CLONE_INTO_CGROUP))
3047 return false;
3048
3049 /*
3050 * - make the CLONE_DETACHED bit reusable for clone3
3051 * - make the CSIGNAL bits reusable for clone3
3052 */
3053 if (kargs->flags & (CLONE_DETACHED | (CSIGNAL & (~CLONE_NEWTIME))))
3054 return false;
3055
3056 if ((kargs->flags & (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND)) ==
3057 (CLONE_SIGHAND | CLONE_CLEAR_SIGHAND))
3058 return false;
3059
3060 if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
3061 kargs->exit_signal)
3062 return false;
3063
3064 if (!clone3_stack_valid(kargs))
3065 return false;
3066
3067 return true;
3068}
3069
3070/**
3071 * sys_clone3 - create a new process with specific properties
3072 * @uargs: argument structure
3073 * @size: size of @uargs
3074 *
3075 * clone3() is the extensible successor to clone()/clone2().
3076 * It takes a struct as argument that is versioned by its size.
3077 *
3078 * Return: On success, a positive PID for the child process.
3079 * On error, a negative errno number.
3080 */
3081SYSCALL_DEFINE2(clone3, struct clone_args __user *, uargs, size_t, size)
3082{
3083 int err;
3084
3085 struct kernel_clone_args kargs;
3086 pid_t set_tid[MAX_PID_NS_LEVEL];
3087
3088 kargs.set_tid = set_tid;
3089
3090 err = copy_clone_args_from_user(&kargs, uargs, size);
3091 if (err)
3092 return err;
3093
3094 if (!clone3_args_valid(&kargs))
3095 return -EINVAL;
3096
3097 return kernel_clone(&kargs);
3098}
3099#endif
3100
3101void walk_process_tree(struct task_struct *top, proc_visitor visitor, void *data)
3102{
3103 struct task_struct *leader, *parent, *child;
3104 int res;
3105
3106 read_lock(&tasklist_lock);
3107 leader = top = top->group_leader;
3108down:
3109 for_each_thread(leader, parent) {
3110 list_for_each_entry(child, &parent->children, sibling) {
3111 res = visitor(child, data);
3112 if (res) {
3113 if (res < 0)
3114 goto out;
3115 leader = child;
3116 goto down;
3117 }
3118up:
3119 ;
3120 }
3121 }
3122
3123 if (leader != top) {
3124 child = leader;
3125 parent = child->real_parent;
3126 leader = parent->group_leader;
3127 goto up;
3128 }
3129out:
3130 read_unlock(&tasklist_lock);
3131}
3132
3133#ifndef ARCH_MIN_MMSTRUCT_ALIGN
3134#define ARCH_MIN_MMSTRUCT_ALIGN 0
3135#endif
3136
3137static void sighand_ctor(void *data)
3138{
3139 struct sighand_struct *sighand = data;
3140
3141 spin_lock_init(&sighand->siglock);
3142 init_waitqueue_head(&sighand->signalfd_wqh);
3143}
3144
3145void __init mm_cache_init(void)
3146{
3147 unsigned int mm_size;
3148
3149 /*
3150 * The mm_cpumask is located at the end of mm_struct, and is
3151 * dynamically sized based on the maximum CPU number this system
3152 * can have, taking hotplug into account (nr_cpu_ids).
3153 */
3154 mm_size = sizeof(struct mm_struct) + cpumask_size() + mm_cid_size();
3155
3156 mm_cachep = kmem_cache_create_usercopy("mm_struct",
3157 mm_size, ARCH_MIN_MMSTRUCT_ALIGN,
3158 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3159 offsetof(struct mm_struct, saved_auxv),
3160 sizeof_field(struct mm_struct, saved_auxv),
3161 NULL);
3162}
3163
3164void __init proc_caches_init(void)
3165{
3166 sighand_cachep = kmem_cache_create("sighand_cache",
3167 sizeof(struct sighand_struct), 0,
3168 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_TYPESAFE_BY_RCU|
3169 SLAB_ACCOUNT, sighand_ctor);
3170 signal_cachep = kmem_cache_create("signal_cache",
3171 sizeof(struct signal_struct), 0,
3172 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3173 NULL);
3174 files_cachep = kmem_cache_create("files_cache",
3175 sizeof(struct files_struct), 0,
3176 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3177 NULL);
3178 fs_cachep = kmem_cache_create("fs_cache",
3179 sizeof(struct fs_struct), 0,
3180 SLAB_HWCACHE_ALIGN|SLAB_PANIC|SLAB_ACCOUNT,
3181 NULL);
3182
3183 vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT);
3184#ifdef CONFIG_PER_VMA_LOCK
3185 vma_lock_cachep = KMEM_CACHE(vma_lock, SLAB_PANIC|SLAB_ACCOUNT);
3186#endif
3187 mmap_init();
3188 nsproxy_cache_init();
3189}
3190
3191/*
3192 * Check constraints on flags passed to the unshare system call.
3193 */
3194static int check_unshare_flags(unsigned long unshare_flags)
3195{
3196 if (unshare_flags & ~(CLONE_THREAD|CLONE_FS|CLONE_NEWNS|CLONE_SIGHAND|
3197 CLONE_VM|CLONE_FILES|CLONE_SYSVSEM|
3198 CLONE_NEWUTS|CLONE_NEWIPC|CLONE_NEWNET|
3199 CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWCGROUP|
3200 CLONE_NEWTIME))
3201 return -EINVAL;
3202 /*
3203 * Not implemented, but pretend it works if there is nothing
3204 * to unshare. Note that unsharing the address space or the
3205 * signal handlers also need to unshare the signal queues (aka
3206 * CLONE_THREAD).
3207 */
3208 if (unshare_flags & (CLONE_THREAD | CLONE_SIGHAND | CLONE_VM)) {
3209 if (!thread_group_empty(current))
3210 return -EINVAL;
3211 }
3212 if (unshare_flags & (CLONE_SIGHAND | CLONE_VM)) {
3213 if (refcount_read(&current->sighand->count) > 1)
3214 return -EINVAL;
3215 }
3216 if (unshare_flags & CLONE_VM) {
3217 if (!current_is_single_threaded())
3218 return -EINVAL;
3219 }
3220
3221 return 0;
3222}
3223
3224/*
3225 * Unshare the filesystem structure if it is being shared
3226 */
3227static int unshare_fs(unsigned long unshare_flags, struct fs_struct **new_fsp)
3228{
3229 struct fs_struct *fs = current->fs;
3230
3231 if (!(unshare_flags & CLONE_FS) || !fs)
3232 return 0;
3233
3234 /* don't need lock here; in the worst case we'll do useless copy */
3235 if (fs->users == 1)
3236 return 0;
3237
3238 *new_fsp = copy_fs_struct(fs);
3239 if (!*new_fsp)
3240 return -ENOMEM;
3241
3242 return 0;
3243}
3244
3245/*
3246 * Unshare file descriptor table if it is being shared
3247 */
3248int unshare_fd(unsigned long unshare_flags, unsigned int max_fds,
3249 struct files_struct **new_fdp)
3250{
3251 struct files_struct *fd = current->files;
3252 int error = 0;
3253
3254 if ((unshare_flags & CLONE_FILES) &&
3255 (fd && atomic_read(&fd->count) > 1)) {
3256 *new_fdp = dup_fd(fd, max_fds, &error);
3257 if (!*new_fdp)
3258 return error;
3259 }
3260
3261 return 0;
3262}
3263
3264/*
3265 * unshare allows a process to 'unshare' part of the process
3266 * context which was originally shared using clone. copy_*
3267 * functions used by kernel_clone() cannot be used here directly
3268 * because they modify an inactive task_struct that is being
3269 * constructed. Here we are modifying the current, active,
3270 * task_struct.
3271 */
3272int ksys_unshare(unsigned long unshare_flags)
3273{
3274 struct fs_struct *fs, *new_fs = NULL;
3275 struct files_struct *new_fd = NULL;
3276 struct cred *new_cred = NULL;
3277 struct nsproxy *new_nsproxy = NULL;
3278 int do_sysvsem = 0;
3279 int err;
3280
3281 /*
3282 * If unsharing a user namespace must also unshare the thread group
3283 * and unshare the filesystem root and working directories.
3284 */
3285 if (unshare_flags & CLONE_NEWUSER)
3286 unshare_flags |= CLONE_THREAD | CLONE_FS;
3287 /*
3288 * If unsharing vm, must also unshare signal handlers.
3289 */
3290 if (unshare_flags & CLONE_VM)
3291 unshare_flags |= CLONE_SIGHAND;
3292 /*
3293 * If unsharing a signal handlers, must also unshare the signal queues.
3294 */
3295 if (unshare_flags & CLONE_SIGHAND)
3296 unshare_flags |= CLONE_THREAD;
3297 /*
3298 * If unsharing namespace, must also unshare filesystem information.
3299 */
3300 if (unshare_flags & CLONE_NEWNS)
3301 unshare_flags |= CLONE_FS;
3302
3303 err = check_unshare_flags(unshare_flags);
3304 if (err)
3305 goto bad_unshare_out;
3306 /*
3307 * CLONE_NEWIPC must also detach from the undolist: after switching
3308 * to a new ipc namespace, the semaphore arrays from the old
3309 * namespace are unreachable.
3310 */
3311 if (unshare_flags & (CLONE_NEWIPC|CLONE_SYSVSEM))
3312 do_sysvsem = 1;
3313 err = unshare_fs(unshare_flags, &new_fs);
3314 if (err)
3315 goto bad_unshare_out;
3316 err = unshare_fd(unshare_flags, NR_OPEN_MAX, &new_fd);
3317 if (err)
3318 goto bad_unshare_cleanup_fs;
3319 err = unshare_userns(unshare_flags, &new_cred);
3320 if (err)
3321 goto bad_unshare_cleanup_fd;
3322 err = unshare_nsproxy_namespaces(unshare_flags, &new_nsproxy,
3323 new_cred, new_fs);
3324 if (err)
3325 goto bad_unshare_cleanup_cred;
3326
3327 if (new_cred) {
3328 err = set_cred_ucounts(new_cred);
3329 if (err)
3330 goto bad_unshare_cleanup_cred;
3331 }
3332
3333 if (new_fs || new_fd || do_sysvsem || new_cred || new_nsproxy) {
3334 if (do_sysvsem) {
3335 /*
3336 * CLONE_SYSVSEM is equivalent to sys_exit().
3337 */
3338 exit_sem(current);
3339 }
3340 if (unshare_flags & CLONE_NEWIPC) {
3341 /* Orphan segments in old ns (see sem above). */
3342 exit_shm(current);
3343 shm_init_task(current);
3344 }
3345
3346 if (new_nsproxy)
3347 switch_task_namespaces(current, new_nsproxy);
3348
3349 task_lock(current);
3350
3351 if (new_fs) {
3352 fs = current->fs;
3353 spin_lock(&fs->lock);
3354 current->fs = new_fs;
3355 if (--fs->users)
3356 new_fs = NULL;
3357 else
3358 new_fs = fs;
3359 spin_unlock(&fs->lock);
3360 }
3361
3362 if (new_fd)
3363 swap(current->files, new_fd);
3364
3365 task_unlock(current);
3366
3367 if (new_cred) {
3368 /* Install the new user namespace */
3369 commit_creds(new_cred);
3370 new_cred = NULL;
3371 }
3372 }
3373
3374 perf_event_namespaces(current);
3375
3376bad_unshare_cleanup_cred:
3377 if (new_cred)
3378 put_cred(new_cred);
3379bad_unshare_cleanup_fd:
3380 if (new_fd)
3381 put_files_struct(new_fd);
3382
3383bad_unshare_cleanup_fs:
3384 if (new_fs)
3385 free_fs_struct(new_fs);
3386
3387bad_unshare_out:
3388 return err;
3389}
3390
3391SYSCALL_DEFINE1(unshare, unsigned long, unshare_flags)
3392{
3393 return ksys_unshare(unshare_flags);
3394}
3395
3396/*
3397 * Helper to unshare the files of the current task.
3398 * We don't want to expose copy_files internals to
3399 * the exec layer of the kernel.
3400 */
3401
3402int unshare_files(void)
3403{
3404 struct task_struct *task = current;
3405 struct files_struct *old, *copy = NULL;
3406 int error;
3407
3408 error = unshare_fd(CLONE_FILES, NR_OPEN_MAX, &copy);
3409 if (error || !copy)
3410 return error;
3411
3412 old = task->files;
3413 task_lock(task);
3414 task->files = copy;
3415 task_unlock(task);
3416 put_files_struct(old);
3417 return 0;
3418}
3419
3420int sysctl_max_threads(struct ctl_table *table, int write,
3421 void *buffer, size_t *lenp, loff_t *ppos)
3422{
3423 struct ctl_table t;
3424 int ret;
3425 int threads = max_threads;
3426 int min = 1;
3427 int max = MAX_THREADS;
3428
3429 t = *table;
3430 t.data = &threads;
3431 t.extra1 = &min;
3432 t.extra2 = &max;
3433
3434 ret = proc_dointvec_minmax(&t, write, buffer, lenp, ppos);
3435 if (ret || !write)
3436 return ret;
3437
3438 max_threads = threads;
3439
3440 return 0;
3441}