1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * mm/mmap.c
4 *
5 * Written by obz.
6 *
7 * Address space accounting code <alan@lxorguk.ukuu.org.uk>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/kernel.h>
13#include <linux/slab.h>
14#include <linux/backing-dev.h>
15#include <linux/mm.h>
16#include <linux/mm_inline.h>
17#include <linux/shm.h>
18#include <linux/mman.h>
19#include <linux/pagemap.h>
20#include <linux/swap.h>
21#include <linux/syscalls.h>
22#include <linux/capability.h>
23#include <linux/init.h>
24#include <linux/file.h>
25#include <linux/fs.h>
26#include <linux/personality.h>
27#include <linux/security.h>
28#include <linux/hugetlb.h>
29#include <linux/shmem_fs.h>
30#include <linux/profile.h>
31#include <linux/export.h>
32#include <linux/mount.h>
33#include <linux/mempolicy.h>
34#include <linux/rmap.h>
35#include <linux/mmu_notifier.h>
36#include <linux/mmdebug.h>
37#include <linux/perf_event.h>
38#include <linux/audit.h>
39#include <linux/khugepaged.h>
40#include <linux/uprobes.h>
41#include <linux/notifier.h>
42#include <linux/memory.h>
43#include <linux/printk.h>
44#include <linux/userfaultfd_k.h>
45#include <linux/moduleparam.h>
46#include <linux/pkeys.h>
47#include <linux/oom.h>
48#include <linux/sched/mm.h>
49#include <linux/ksm.h>
50
51#include <linux/uaccess.h>
52#include <asm/cacheflush.h>
53#include <asm/tlb.h>
54#include <asm/mmu_context.h>
55
56#define CREATE_TRACE_POINTS
57#include <trace/events/mmap.h>
58
59#include "internal.h"
60
61#ifndef arch_mmap_check
62#define arch_mmap_check(addr, len, flags) (0)
63#endif
64
65#ifdef CONFIG_HAVE_ARCH_MMAP_RND_BITS
66const int mmap_rnd_bits_min = CONFIG_ARCH_MMAP_RND_BITS_MIN;
67const int mmap_rnd_bits_max = CONFIG_ARCH_MMAP_RND_BITS_MAX;
68int mmap_rnd_bits __read_mostly = CONFIG_ARCH_MMAP_RND_BITS;
69#endif
70#ifdef CONFIG_HAVE_ARCH_MMAP_RND_COMPAT_BITS
71const int mmap_rnd_compat_bits_min = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MIN;
72const int mmap_rnd_compat_bits_max = CONFIG_ARCH_MMAP_RND_COMPAT_BITS_MAX;
73int mmap_rnd_compat_bits __read_mostly = CONFIG_ARCH_MMAP_RND_COMPAT_BITS;
74#endif
75
76static bool ignore_rlimit_data;
77core_param(ignore_rlimit_data, ignore_rlimit_data, bool, 0644);
78
79static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
80 struct vm_area_struct *vma, struct vm_area_struct *prev,
81 struct vm_area_struct *next, unsigned long start,
82 unsigned long end, unsigned long tree_end, bool mm_wr_locked);
83
84static pgprot_t vm_pgprot_modify(pgprot_t oldprot, unsigned long vm_flags)
85{
86 return pgprot_modify(oldprot, newprot: vm_get_page_prot(vm_flags));
87}
88
89/* Update vma->vm_page_prot to reflect vma->vm_flags. */
90void vma_set_page_prot(struct vm_area_struct *vma)
91{
92 unsigned long vm_flags = vma->vm_flags;
93 pgprot_t vm_page_prot;
94
95 vm_page_prot = vm_pgprot_modify(oldprot: vma->vm_page_prot, vm_flags);
96 if (vma_wants_writenotify(vma, vm_page_prot)) {
97 vm_flags &= ~VM_SHARED;
98 vm_page_prot = vm_pgprot_modify(oldprot: vm_page_prot, vm_flags);
99 }
100 /* remove_protection_ptes reads vma->vm_page_prot without mmap_lock */
101 WRITE_ONCE(vma->vm_page_prot, vm_page_prot);
102}
103
104/*
105 * Requires inode->i_mapping->i_mmap_rwsem
106 */
107static void __remove_shared_vm_struct(struct vm_area_struct *vma,
108 struct file *file, struct address_space *mapping)
109{
110 if (vma_is_shared_maywrite(vma))
111 mapping_unmap_writable(mapping);
112
113 flush_dcache_mmap_lock(mapping);
114 vma_interval_tree_remove(node: vma, root: &mapping->i_mmap);
115 flush_dcache_mmap_unlock(mapping);
116}
117
118/*
119 * Unlink a file-based vm structure from its interval tree, to hide
120 * vma from rmap and vmtruncate before freeing its page tables.
121 */
122void unlink_file_vma(struct vm_area_struct *vma)
123{
124 struct file *file = vma->vm_file;
125
126 if (file) {
127 struct address_space *mapping = file->f_mapping;
128 i_mmap_lock_write(mapping);
129 __remove_shared_vm_struct(vma, file, mapping);
130 i_mmap_unlock_write(mapping);
131 }
132}
133
134/*
135 * Close a vm structure and free it.
136 */
137static void remove_vma(struct vm_area_struct *vma, bool unreachable)
138{
139 might_sleep();
140 if (vma->vm_ops && vma->vm_ops->close)
141 vma->vm_ops->close(vma);
142 if (vma->vm_file)
143 fput(vma->vm_file);
144 mpol_put(vma_policy(vma));
145 if (unreachable)
146 __vm_area_free(vma);
147 else
148 vm_area_free(vma);
149}
150
151static inline struct vm_area_struct *vma_prev_limit(struct vma_iterator *vmi,
152 unsigned long min)
153{
154 return mas_prev(mas: &vmi->mas, min);
155}
156
157/*
158 * check_brk_limits() - Use platform specific check of range & verify mlock
159 * limits.
160 * @addr: The address to check
161 * @len: The size of increase.
162 *
163 * Return: 0 on success.
164 */
165static int check_brk_limits(unsigned long addr, unsigned long len)
166{
167 unsigned long mapped_addr;
168
169 mapped_addr = get_unmapped_area(NULL, addr, len, 0, MAP_FIXED);
170 if (IS_ERR_VALUE(mapped_addr))
171 return mapped_addr;
172
173 return mlock_future_ok(current->mm, current->mm->def_flags, bytes: len)
174 ? 0 : -EAGAIN;
175}
176static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *brkvma,
177 unsigned long addr, unsigned long request, unsigned long flags);
178SYSCALL_DEFINE1(brk, unsigned long, brk)
179{
180 unsigned long newbrk, oldbrk, origbrk;
181 struct mm_struct *mm = current->mm;
182 struct vm_area_struct *brkvma, *next = NULL;
183 unsigned long min_brk;
184 bool populate = false;
185 LIST_HEAD(uf);
186 struct vma_iterator vmi;
187
188 if (mmap_write_lock_killable(mm))
189 return -EINTR;
190
191 origbrk = mm->brk;
192
193#ifdef CONFIG_COMPAT_BRK
194 /*
195 * CONFIG_COMPAT_BRK can still be overridden by setting
196 * randomize_va_space to 2, which will still cause mm->start_brk
197 * to be arbitrarily shifted
198 */
199 if (current->brk_randomized)
200 min_brk = mm->start_brk;
201 else
202 min_brk = mm->end_data;
203#else
204 min_brk = mm->start_brk;
205#endif
206 if (brk < min_brk)
207 goto out;
208
209 /*
210 * Check against rlimit here. If this check is done later after the test
211 * of oldbrk with newbrk then it can escape the test and let the data
212 * segment grow beyond its set limit the in case where the limit is
213 * not page aligned -Ram Gupta
214 */
215 if (check_data_rlimit(rlim: rlimit(RLIMIT_DATA), new: brk, start: mm->start_brk,
216 end_data: mm->end_data, start_data: mm->start_data))
217 goto out;
218
219 newbrk = PAGE_ALIGN(brk);
220 oldbrk = PAGE_ALIGN(mm->brk);
221 if (oldbrk == newbrk) {
222 mm->brk = brk;
223 goto success;
224 }
225
226 /* Always allow shrinking brk. */
227 if (brk <= mm->brk) {
228 /* Search one past newbrk */
229 vma_iter_init(vmi: &vmi, mm, addr: newbrk);
230 brkvma = vma_find(vmi: &vmi, max: oldbrk);
231 if (!brkvma || brkvma->vm_start >= oldbrk)
232 goto out; /* mapping intersects with an existing non-brk vma. */
233 /*
234 * mm->brk must be protected by write mmap_lock.
235 * do_vma_munmap() will drop the lock on success, so update it
236 * before calling do_vma_munmap().
237 */
238 mm->brk = brk;
239 if (do_vma_munmap(vmi: &vmi, vma: brkvma, start: newbrk, end: oldbrk, uf: &uf, unlock: true))
240 goto out;
241
242 goto success_unlocked;
243 }
244
245 if (check_brk_limits(addr: oldbrk, len: newbrk - oldbrk))
246 goto out;
247
248 /*
249 * Only check if the next VMA is within the stack_guard_gap of the
250 * expansion area
251 */
252 vma_iter_init(vmi: &vmi, mm, addr: oldbrk);
253 next = vma_find(vmi: &vmi, max: newbrk + PAGE_SIZE + stack_guard_gap);
254 if (next && newbrk + PAGE_SIZE > vm_start_gap(vma: next))
255 goto out;
256
257 brkvma = vma_prev_limit(vmi: &vmi, min: mm->start_brk);
258 /* Ok, looks good - let it rip. */
259 if (do_brk_flags(vmi: &vmi, brkvma, addr: oldbrk, request: newbrk - oldbrk, flags: 0) < 0)
260 goto out;
261
262 mm->brk = brk;
263 if (mm->def_flags & VM_LOCKED)
264 populate = true;
265
266success:
267 mmap_write_unlock(mm);
268success_unlocked:
269 userfaultfd_unmap_complete(mm, uf: &uf);
270 if (populate)
271 mm_populate(addr: oldbrk, len: newbrk - oldbrk);
272 return brk;
273
274out:
275 mm->brk = origbrk;
276 mmap_write_unlock(mm);
277 return origbrk;
278}
279
280#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
281static void validate_mm(struct mm_struct *mm)
282{
283 int bug = 0;
284 int i = 0;
285 struct vm_area_struct *vma;
286 VMA_ITERATOR(vmi, mm, 0);
287
288 mt_validate(mt: &mm->mm_mt);
289 for_each_vma(vmi, vma) {
290#ifdef CONFIG_DEBUG_VM_RB
291 struct anon_vma *anon_vma = vma->anon_vma;
292 struct anon_vma_chain *avc;
293#endif
294 unsigned long vmi_start, vmi_end;
295 bool warn = 0;
296
297 vmi_start = vma_iter_addr(vmi: &vmi);
298 vmi_end = vma_iter_end(vmi: &vmi);
299 if (VM_WARN_ON_ONCE_MM(vma->vm_end != vmi_end, mm))
300 warn = 1;
301
302 if (VM_WARN_ON_ONCE_MM(vma->vm_start != vmi_start, mm))
303 warn = 1;
304
305 if (warn) {
306 pr_emerg("issue in %s\n", current->comm);
307 dump_stack();
308 dump_vma(vma);
309 pr_emerg("tree range: %px start %lx end %lx\n", vma,
310 vmi_start, vmi_end - 1);
311 vma_iter_dump_tree(vmi: &vmi);
312 }
313
314#ifdef CONFIG_DEBUG_VM_RB
315 if (anon_vma) {
316 anon_vma_lock_read(anon_vma);
317 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
318 anon_vma_interval_tree_verify(node: avc);
319 anon_vma_unlock_read(anon_vma);
320 }
321#endif
322 i++;
323 }
324 if (i != mm->map_count) {
325 pr_emerg("map_count %d vma iterator %d\n", mm->map_count, i);
326 bug = 1;
327 }
328 VM_BUG_ON_MM(bug, mm);
329}
330
331#else /* !CONFIG_DEBUG_VM_MAPLE_TREE */
332#define validate_mm(mm) do { } while (0)
333#endif /* CONFIG_DEBUG_VM_MAPLE_TREE */
334
335/*
336 * vma has some anon_vma assigned, and is already inserted on that
337 * anon_vma's interval trees.
338 *
339 * Before updating the vma's vm_start / vm_end / vm_pgoff fields, the
340 * vma must be removed from the anon_vma's interval trees using
341 * anon_vma_interval_tree_pre_update_vma().
342 *
343 * After the update, the vma will be reinserted using
344 * anon_vma_interval_tree_post_update_vma().
345 *
346 * The entire update must be protected by exclusive mmap_lock and by
347 * the root anon_vma's mutex.
348 */
349static inline void
350anon_vma_interval_tree_pre_update_vma(struct vm_area_struct *vma)
351{
352 struct anon_vma_chain *avc;
353
354 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
355 anon_vma_interval_tree_remove(node: avc, root: &avc->anon_vma->rb_root);
356}
357
358static inline void
359anon_vma_interval_tree_post_update_vma(struct vm_area_struct *vma)
360{
361 struct anon_vma_chain *avc;
362
363 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
364 anon_vma_interval_tree_insert(node: avc, root: &avc->anon_vma->rb_root);
365}
366
367static unsigned long count_vma_pages_range(struct mm_struct *mm,
368 unsigned long addr, unsigned long end)
369{
370 VMA_ITERATOR(vmi, mm, addr);
371 struct vm_area_struct *vma;
372 unsigned long nr_pages = 0;
373
374 for_each_vma_range(vmi, vma, end) {
375 unsigned long vm_start = max(addr, vma->vm_start);
376 unsigned long vm_end = min(end, vma->vm_end);
377
378 nr_pages += PHYS_PFN(vm_end - vm_start);
379 }
380
381 return nr_pages;
382}
383
384static void __vma_link_file(struct vm_area_struct *vma,
385 struct address_space *mapping)
386{
387 if (vma_is_shared_maywrite(vma))
388 mapping_allow_writable(mapping);
389
390 flush_dcache_mmap_lock(mapping);
391 vma_interval_tree_insert(node: vma, root: &mapping->i_mmap);
392 flush_dcache_mmap_unlock(mapping);
393}
394
395static int vma_link(struct mm_struct *mm, struct vm_area_struct *vma)
396{
397 VMA_ITERATOR(vmi, mm, 0);
398 struct address_space *mapping = NULL;
399
400 vma_iter_config(vmi: &vmi, index: vma->vm_start, last: vma->vm_end);
401 if (vma_iter_prealloc(vmi: &vmi, vma))
402 return -ENOMEM;
403
404 vma_start_write(vma);
405
406 vma_iter_store(vmi: &vmi, vma);
407
408 if (vma->vm_file) {
409 mapping = vma->vm_file->f_mapping;
410 i_mmap_lock_write(mapping);
411 __vma_link_file(vma, mapping);
412 i_mmap_unlock_write(mapping);
413 }
414
415 mm->map_count++;
416 validate_mm(mm);
417 return 0;
418}
419
420/*
421 * init_multi_vma_prep() - Initializer for struct vma_prepare
422 * @vp: The vma_prepare struct
423 * @vma: The vma that will be altered once locked
424 * @next: The next vma if it is to be adjusted
425 * @remove: The first vma to be removed
426 * @remove2: The second vma to be removed
427 */
428static inline void init_multi_vma_prep(struct vma_prepare *vp,
429 struct vm_area_struct *vma, struct vm_area_struct *next,
430 struct vm_area_struct *remove, struct vm_area_struct *remove2)
431{
432 memset(vp, 0, sizeof(struct vma_prepare));
433 vp->vma = vma;
434 vp->anon_vma = vma->anon_vma;
435 vp->remove = remove;
436 vp->remove2 = remove2;
437 vp->adj_next = next;
438 if (!vp->anon_vma && next)
439 vp->anon_vma = next->anon_vma;
440
441 vp->file = vma->vm_file;
442 if (vp->file)
443 vp->mapping = vma->vm_file->f_mapping;
444
445}
446
447/*
448 * init_vma_prep() - Initializer wrapper for vma_prepare struct
449 * @vp: The vma_prepare struct
450 * @vma: The vma that will be altered once locked
451 */
452static inline void init_vma_prep(struct vma_prepare *vp,
453 struct vm_area_struct *vma)
454{
455 init_multi_vma_prep(vp, vma, NULL, NULL, NULL);
456}
457
458
459/*
460 * vma_prepare() - Helper function for handling locking VMAs prior to altering
461 * @vp: The initialized vma_prepare struct
462 */
463static inline void vma_prepare(struct vma_prepare *vp)
464{
465 if (vp->file) {
466 uprobe_munmap(vma: vp->vma, start: vp->vma->vm_start, end: vp->vma->vm_end);
467
468 if (vp->adj_next)
469 uprobe_munmap(vma: vp->adj_next, start: vp->adj_next->vm_start,
470 end: vp->adj_next->vm_end);
471
472 i_mmap_lock_write(mapping: vp->mapping);
473 if (vp->insert && vp->insert->vm_file) {
474 /*
475 * Put into interval tree now, so instantiated pages
476 * are visible to arm/parisc __flush_dcache_page
477 * throughout; but we cannot insert into address
478 * space until vma start or end is updated.
479 */
480 __vma_link_file(vma: vp->insert,
481 mapping: vp->insert->vm_file->f_mapping);
482 }
483 }
484
485 if (vp->anon_vma) {
486 anon_vma_lock_write(anon_vma: vp->anon_vma);
487 anon_vma_interval_tree_pre_update_vma(vma: vp->vma);
488 if (vp->adj_next)
489 anon_vma_interval_tree_pre_update_vma(vma: vp->adj_next);
490 }
491
492 if (vp->file) {
493 flush_dcache_mmap_lock(mapping: vp->mapping);
494 vma_interval_tree_remove(node: vp->vma, root: &vp->mapping->i_mmap);
495 if (vp->adj_next)
496 vma_interval_tree_remove(node: vp->adj_next,
497 root: &vp->mapping->i_mmap);
498 }
499
500}
501
502/*
503 * vma_complete- Helper function for handling the unlocking after altering VMAs,
504 * or for inserting a VMA.
505 *
506 * @vp: The vma_prepare struct
507 * @vmi: The vma iterator
508 * @mm: The mm_struct
509 */
510static inline void vma_complete(struct vma_prepare *vp,
511 struct vma_iterator *vmi, struct mm_struct *mm)
512{
513 if (vp->file) {
514 if (vp->adj_next)
515 vma_interval_tree_insert(node: vp->adj_next,
516 root: &vp->mapping->i_mmap);
517 vma_interval_tree_insert(node: vp->vma, root: &vp->mapping->i_mmap);
518 flush_dcache_mmap_unlock(mapping: vp->mapping);
519 }
520
521 if (vp->remove && vp->file) {
522 __remove_shared_vm_struct(vma: vp->remove, file: vp->file, mapping: vp->mapping);
523 if (vp->remove2)
524 __remove_shared_vm_struct(vma: vp->remove2, file: vp->file,
525 mapping: vp->mapping);
526 } else if (vp->insert) {
527 /*
528 * split_vma has split insert from vma, and needs
529 * us to insert it before dropping the locks
530 * (it may either follow vma or precede it).
531 */
532 vma_iter_store(vmi, vma: vp->insert);
533 mm->map_count++;
534 }
535
536 if (vp->anon_vma) {
537 anon_vma_interval_tree_post_update_vma(vma: vp->vma);
538 if (vp->adj_next)
539 anon_vma_interval_tree_post_update_vma(vma: vp->adj_next);
540 anon_vma_unlock_write(anon_vma: vp->anon_vma);
541 }
542
543 if (vp->file) {
544 i_mmap_unlock_write(mapping: vp->mapping);
545 uprobe_mmap(vma: vp->vma);
546
547 if (vp->adj_next)
548 uprobe_mmap(vma: vp->adj_next);
549 }
550
551 if (vp->remove) {
552again:
553 vma_mark_detached(vma: vp->remove, detached: true);
554 if (vp->file) {
555 uprobe_munmap(vma: vp->remove, start: vp->remove->vm_start,
556 end: vp->remove->vm_end);
557 fput(vp->file);
558 }
559 if (vp->remove->anon_vma)
560 anon_vma_merge(vma: vp->vma, next: vp->remove);
561 mm->map_count--;
562 mpol_put(vma_policy(vp->remove));
563 if (!vp->remove2)
564 WARN_ON_ONCE(vp->vma->vm_end < vp->remove->vm_end);
565 vm_area_free(vp->remove);
566
567 /*
568 * In mprotect's case 6 (see comments on vma_merge),
569 * we are removing both mid and next vmas
570 */
571 if (vp->remove2) {
572 vp->remove = vp->remove2;
573 vp->remove2 = NULL;
574 goto again;
575 }
576 }
577 if (vp->insert && vp->file)
578 uprobe_mmap(vma: vp->insert);
579 validate_mm(mm);
580}
581
582/*
583 * dup_anon_vma() - Helper function to duplicate anon_vma
584 * @dst: The destination VMA
585 * @src: The source VMA
586 * @dup: Pointer to the destination VMA when successful.
587 *
588 * Returns: 0 on success.
589 */
590static inline int dup_anon_vma(struct vm_area_struct *dst,
591 struct vm_area_struct *src, struct vm_area_struct **dup)
592{
593 /*
594 * Easily overlooked: when mprotect shifts the boundary, make sure the
595 * expanding vma has anon_vma set if the shrinking vma had, to cover any
596 * anon pages imported.
597 */
598 if (src->anon_vma && !dst->anon_vma) {
599 int ret;
600
601 vma_assert_write_locked(vma: dst);
602 dst->anon_vma = src->anon_vma;
603 ret = anon_vma_clone(dst, src);
604 if (ret)
605 return ret;
606
607 *dup = dst;
608 }
609
610 return 0;
611}
612
613/*
614 * vma_expand - Expand an existing VMA
615 *
616 * @vmi: The vma iterator
617 * @vma: The vma to expand
618 * @start: The start of the vma
619 * @end: The exclusive end of the vma
620 * @pgoff: The page offset of vma
621 * @next: The current of next vma.
622 *
623 * Expand @vma to @start and @end. Can expand off the start and end. Will
624 * expand over @next if it's different from @vma and @end == @next->vm_end.
625 * Checking if the @vma can expand and merge with @next needs to be handled by
626 * the caller.
627 *
628 * Returns: 0 on success
629 */
630int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma,
631 unsigned long start, unsigned long end, pgoff_t pgoff,
632 struct vm_area_struct *next)
633{
634 struct vm_area_struct *anon_dup = NULL;
635 bool remove_next = false;
636 struct vma_prepare vp;
637
638 vma_start_write(vma);
639 if (next && (vma != next) && (end == next->vm_end)) {
640 int ret;
641
642 remove_next = true;
643 vma_start_write(vma: next);
644 ret = dup_anon_vma(dst: vma, src: next, dup: &anon_dup);
645 if (ret)
646 return ret;
647 }
648
649 init_multi_vma_prep(vp: &vp, vma, NULL, remove: remove_next ? next : NULL, NULL);
650 /* Not merging but overwriting any part of next is not handled. */
651 VM_WARN_ON(next && !vp.remove &&
652 next != vma && end > next->vm_start);
653 /* Only handles expanding */
654 VM_WARN_ON(vma->vm_start < start || vma->vm_end > end);
655
656 /* Note: vma iterator must be pointing to 'start' */
657 vma_iter_config(vmi, index: start, last: end);
658 if (vma_iter_prealloc(vmi, vma))
659 goto nomem;
660
661 vma_prepare(vp: &vp);
662 vma_adjust_trans_huge(vma, start, end, adjust_next: 0);
663 vma->vm_start = start;
664 vma->vm_end = end;
665 vma->vm_pgoff = pgoff;
666 vma_iter_store(vmi, vma);
667
668 vma_complete(vp: &vp, vmi, mm: vma->vm_mm);
669 return 0;
670
671nomem:
672 if (anon_dup)
673 unlink_anon_vmas(anon_dup);
674 return -ENOMEM;
675}
676
677/*
678 * vma_shrink() - Reduce an existing VMAs memory area
679 * @vmi: The vma iterator
680 * @vma: The VMA to modify
681 * @start: The new start
682 * @end: The new end
683 *
684 * Returns: 0 on success, -ENOMEM otherwise
685 */
686int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma,
687 unsigned long start, unsigned long end, pgoff_t pgoff)
688{
689 struct vma_prepare vp;
690
691 WARN_ON((vma->vm_start != start) && (vma->vm_end != end));
692
693 if (vma->vm_start < start)
694 vma_iter_config(vmi, index: vma->vm_start, last: start);
695 else
696 vma_iter_config(vmi, index: end, last: vma->vm_end);
697
698 if (vma_iter_prealloc(vmi, NULL))
699 return -ENOMEM;
700
701 vma_start_write(vma);
702
703 init_vma_prep(vp: &vp, vma);
704 vma_prepare(vp: &vp);
705 vma_adjust_trans_huge(vma, start, end, adjust_next: 0);
706
707 vma_iter_clear(vmi);
708 vma->vm_start = start;
709 vma->vm_end = end;
710 vma->vm_pgoff = pgoff;
711 vma_complete(vp: &vp, vmi, mm: vma->vm_mm);
712 return 0;
713}
714
715/*
716 * If the vma has a ->close operation then the driver probably needs to release
717 * per-vma resources, so we don't attempt to merge those if the caller indicates
718 * the current vma may be removed as part of the merge.
719 */
720static inline bool is_mergeable_vma(struct vm_area_struct *vma,
721 struct file *file, unsigned long vm_flags,
722 struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
723 struct anon_vma_name *anon_name, bool may_remove_vma)
724{
725 /*
726 * VM_SOFTDIRTY should not prevent from VMA merging, if we
727 * match the flags but dirty bit -- the caller should mark
728 * merged VMA as dirty. If dirty bit won't be excluded from
729 * comparison, we increase pressure on the memory system forcing
730 * the kernel to generate new VMAs when old one could be
731 * extended instead.
732 */
733 if ((vma->vm_flags ^ vm_flags) & ~VM_SOFTDIRTY)
734 return false;
735 if (vma->vm_file != file)
736 return false;
737 if (may_remove_vma && vma->vm_ops && vma->vm_ops->close)
738 return false;
739 if (!is_mergeable_vm_userfaultfd_ctx(vma, vm_ctx: vm_userfaultfd_ctx))
740 return false;
741 if (!anon_vma_name_eq(anon_name1: anon_vma_name(vma), anon_name2: anon_name))
742 return false;
743 return true;
744}
745
746static inline bool is_mergeable_anon_vma(struct anon_vma *anon_vma1,
747 struct anon_vma *anon_vma2, struct vm_area_struct *vma)
748{
749 /*
750 * The list_is_singular() test is to avoid merging VMA cloned from
751 * parents. This can improve scalability caused by anon_vma lock.
752 */
753 if ((!anon_vma1 || !anon_vma2) && (!vma ||
754 list_is_singular(head: &vma->anon_vma_chain)))
755 return true;
756 return anon_vma1 == anon_vma2;
757}
758
759/*
760 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
761 * in front of (at a lower virtual address and file offset than) the vma.
762 *
763 * We cannot merge two vmas if they have differently assigned (non-NULL)
764 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
765 *
766 * We don't check here for the merged mmap wrapping around the end of pagecache
767 * indices (16TB on ia32) because do_mmap() does not permit mmap's which
768 * wrap, nor mmaps which cover the final page at index -1UL.
769 *
770 * We assume the vma may be removed as part of the merge.
771 */
772static bool
773can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
774 struct anon_vma *anon_vma, struct file *file,
775 pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
776 struct anon_vma_name *anon_name)
777{
778 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, may_remove_vma: true) &&
779 is_mergeable_anon_vma(anon_vma1: anon_vma, anon_vma2: vma->anon_vma, vma)) {
780 if (vma->vm_pgoff == vm_pgoff)
781 return true;
782 }
783 return false;
784}
785
786/*
787 * Return true if we can merge this (vm_flags,anon_vma,file,vm_pgoff)
788 * beyond (at a higher virtual address and file offset than) the vma.
789 *
790 * We cannot merge two vmas if they have differently assigned (non-NULL)
791 * anon_vmas, nor if same anon_vma is assigned but offsets incompatible.
792 *
793 * We assume that vma is not removed as part of the merge.
794 */
795static bool
796can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
797 struct anon_vma *anon_vma, struct file *file,
798 pgoff_t vm_pgoff, struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
799 struct anon_vma_name *anon_name)
800{
801 if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, may_remove_vma: false) &&
802 is_mergeable_anon_vma(anon_vma1: anon_vma, anon_vma2: vma->anon_vma, vma)) {
803 pgoff_t vm_pglen;
804 vm_pglen = vma_pages(vma);
805 if (vma->vm_pgoff + vm_pglen == vm_pgoff)
806 return true;
807 }
808 return false;
809}
810
811/*
812 * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
813 * figure out whether that can be merged with its predecessor or its
814 * successor. Or both (it neatly fills a hole).
815 *
816 * In most cases - when called for mmap, brk or mremap - [addr,end) is
817 * certain not to be mapped by the time vma_merge is called; but when
818 * called for mprotect, it is certain to be already mapped (either at
819 * an offset within prev, or at the start of next), and the flags of
820 * this area are about to be changed to vm_flags - and the no-change
821 * case has already been eliminated.
822 *
823 * The following mprotect cases have to be considered, where **** is
824 * the area passed down from mprotect_fixup, never extending beyond one
825 * vma, PPPP is the previous vma, CCCC is a concurrent vma that starts
826 * at the same address as **** and is of the same or larger span, and
827 * NNNN the next vma after ****:
828 *
829 * **** **** ****
830 * PPPPPPNNNNNN PPPPPPNNNNNN PPPPPPCCCCCC
831 * cannot merge might become might become
832 * PPNNNNNNNNNN PPPPPPPPPPCC
833 * mmap, brk or case 4 below case 5 below
834 * mremap move:
835 * **** ****
836 * PPPP NNNN PPPPCCCCNNNN
837 * might become might become
838 * PPPPPPPPPPPP 1 or PPPPPPPPPPPP 6 or
839 * PPPPPPPPNNNN 2 or PPPPPPPPNNNN 7 or
840 * PPPPNNNNNNNN 3 PPPPNNNNNNNN 8
841 *
842 * It is important for case 8 that the vma CCCC overlapping the
843 * region **** is never going to extended over NNNN. Instead NNNN must
844 * be extended in region **** and CCCC must be removed. This way in
845 * all cases where vma_merge succeeds, the moment vma_merge drops the
846 * rmap_locks, the properties of the merged vma will be already
847 * correct for the whole merged range. Some of those properties like
848 * vm_page_prot/vm_flags may be accessed by rmap_walks and they must
849 * be correct for the whole merged range immediately after the
850 * rmap_locks are released. Otherwise if NNNN would be removed and
851 * CCCC would be extended over the NNNN range, remove_migration_ptes
852 * or other rmap walkers (if working on addresses beyond the "end"
853 * parameter) may establish ptes with the wrong permissions of CCCC
854 * instead of the right permissions of NNNN.
855 *
856 * In the code below:
857 * PPPP is represented by *prev
858 * CCCC is represented by *curr or not represented at all (NULL)
859 * NNNN is represented by *next or not represented at all (NULL)
860 * **** is not represented - it will be merged and the vma containing the
861 * area is returned, or the function will return NULL
862 */
863static struct vm_area_struct
864*vma_merge(struct vma_iterator *vmi, struct mm_struct *mm,
865 struct vm_area_struct *prev, unsigned long addr, unsigned long end,
866 unsigned long vm_flags, struct anon_vma *anon_vma, struct file *file,
867 pgoff_t pgoff, struct mempolicy *policy,
868 struct vm_userfaultfd_ctx vm_userfaultfd_ctx,
869 struct anon_vma_name *anon_name)
870{
871 struct vm_area_struct *curr, *next, *res;
872 struct vm_area_struct *vma, *adjust, *remove, *remove2;
873 struct vm_area_struct *anon_dup = NULL;
874 struct vma_prepare vp;
875 pgoff_t vma_pgoff;
876 int err = 0;
877 bool merge_prev = false;
878 bool merge_next = false;
879 bool vma_expanded = false;
880 unsigned long vma_start = addr;
881 unsigned long vma_end = end;
882 pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
883 long adj_start = 0;
884
885 /*
886 * We later require that vma->vm_flags == vm_flags,
887 * so this tests vma->vm_flags & VM_SPECIAL, too.
888 */
889 if (vm_flags & VM_SPECIAL)
890 return NULL;
891
892 /* Does the input range span an existing VMA? (cases 5 - 8) */
893 curr = find_vma_intersection(mm, start_addr: prev ? prev->vm_end : 0, end_addr: end);
894
895 if (!curr || /* cases 1 - 4 */
896 end == curr->vm_end) /* cases 6 - 8, adjacent VMA */
897 next = vma_lookup(mm, addr: end);
898 else
899 next = NULL; /* case 5 */
900
901 if (prev) {
902 vma_start = prev->vm_start;
903 vma_pgoff = prev->vm_pgoff;
904
905 /* Can we merge the predecessor? */
906 if (addr == prev->vm_end && mpol_equal(vma_policy(prev), b: policy)
907 && can_vma_merge_after(vma: prev, vm_flags, anon_vma, file,
908 vm_pgoff: pgoff, vm_userfaultfd_ctx, anon_name)) {
909 merge_prev = true;
910 vma_prev(vmi);
911 }
912 }
913
914 /* Can we merge the successor? */
915 if (next && mpol_equal(a: policy, vma_policy(next)) &&
916 can_vma_merge_before(vma: next, vm_flags, anon_vma, file, vm_pgoff: pgoff+pglen,
917 vm_userfaultfd_ctx, anon_name)) {
918 merge_next = true;
919 }
920
921 /* Verify some invariant that must be enforced by the caller. */
922 VM_WARN_ON(prev && addr <= prev->vm_start);
923 VM_WARN_ON(curr && (addr != curr->vm_start || end > curr->vm_end));
924 VM_WARN_ON(addr >= end);
925
926 if (!merge_prev && !merge_next)
927 return NULL; /* Not mergeable. */
928
929 if (merge_prev)
930 vma_start_write(vma: prev);
931
932 res = vma = prev;
933 remove = remove2 = adjust = NULL;
934
935 /* Can we merge both the predecessor and the successor? */
936 if (merge_prev && merge_next &&
937 is_mergeable_anon_vma(anon_vma1: prev->anon_vma, anon_vma2: next->anon_vma, NULL)) {
938 vma_start_write(vma: next);
939 remove = next; /* case 1 */
940 vma_end = next->vm_end;
941 err = dup_anon_vma(dst: prev, src: next, dup: &anon_dup);
942 if (curr) { /* case 6 */
943 vma_start_write(vma: curr);
944 remove = curr;
945 remove2 = next;
946 /*
947 * Note that the dup_anon_vma below cannot overwrite err
948 * since the first caller would do nothing unless next
949 * has an anon_vma.
950 */
951 if (!next->anon_vma)
952 err = dup_anon_vma(dst: prev, src: curr, dup: &anon_dup);
953 }
954 } else if (merge_prev) { /* case 2 */
955 if (curr) {
956 vma_start_write(vma: curr);
957 err = dup_anon_vma(dst: prev, src: curr, dup: &anon_dup);
958 if (end == curr->vm_end) { /* case 7 */
959 remove = curr;
960 } else { /* case 5 */
961 adjust = curr;
962 adj_start = (end - curr->vm_start);
963 }
964 }
965 } else { /* merge_next */
966 vma_start_write(vma: next);
967 res = next;
968 if (prev && addr < prev->vm_end) { /* case 4 */
969 vma_start_write(vma: prev);
970 vma_end = addr;
971 adjust = next;
972 adj_start = -(prev->vm_end - addr);
973 err = dup_anon_vma(dst: next, src: prev, dup: &anon_dup);
974 } else {
975 /*
976 * Note that cases 3 and 8 are the ONLY ones where prev
977 * is permitted to be (but is not necessarily) NULL.
978 */
979 vma = next; /* case 3 */
980 vma_start = addr;
981 vma_end = next->vm_end;
982 vma_pgoff = next->vm_pgoff - pglen;
983 if (curr) { /* case 8 */
984 vma_pgoff = curr->vm_pgoff;
985 vma_start_write(vma: curr);
986 remove = curr;
987 err = dup_anon_vma(dst: next, src: curr, dup: &anon_dup);
988 }
989 }
990 }
991
992 /* Error in anon_vma clone. */
993 if (err)
994 goto anon_vma_fail;
995
996 if (vma_start < vma->vm_start || vma_end > vma->vm_end)
997 vma_expanded = true;
998
999 if (vma_expanded) {
1000 vma_iter_config(vmi, index: vma_start, last: vma_end);
1001 } else {
1002 vma_iter_config(vmi, index: adjust->vm_start + adj_start,
1003 last: adjust->vm_end);
1004 }
1005
1006 if (vma_iter_prealloc(vmi, vma))
1007 goto prealloc_fail;
1008
1009 init_multi_vma_prep(vp: &vp, vma, next: adjust, remove, remove2);
1010 VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma &&
1011 vp.anon_vma != adjust->anon_vma);
1012
1013 vma_prepare(vp: &vp);
1014 vma_adjust_trans_huge(vma, start: vma_start, end: vma_end, adjust_next: adj_start);
1015
1016 vma->vm_start = vma_start;
1017 vma->vm_end = vma_end;
1018 vma->vm_pgoff = vma_pgoff;
1019
1020 if (vma_expanded)
1021 vma_iter_store(vmi, vma);
1022
1023 if (adj_start) {
1024 adjust->vm_start += adj_start;
1025 adjust->vm_pgoff += adj_start >> PAGE_SHIFT;
1026 if (adj_start < 0) {
1027 WARN_ON(vma_expanded);
1028 vma_iter_store(vmi, vma: next);
1029 }
1030 }
1031
1032 vma_complete(vp: &vp, vmi, mm);
1033 khugepaged_enter_vma(vma: res, vm_flags);
1034 return res;
1035
1036prealloc_fail:
1037 if (anon_dup)
1038 unlink_anon_vmas(anon_dup);
1039
1040anon_vma_fail:
1041 vma_iter_set(vmi, addr);
1042 vma_iter_load(vmi);
1043 return NULL;
1044}
1045
1046/*
1047 * Rough compatibility check to quickly see if it's even worth looking
1048 * at sharing an anon_vma.
1049 *
1050 * They need to have the same vm_file, and the flags can only differ
1051 * in things that mprotect may change.
1052 *
1053 * NOTE! The fact that we share an anon_vma doesn't _have_ to mean that
1054 * we can merge the two vma's. For example, we refuse to merge a vma if
1055 * there is a vm_ops->close() function, because that indicates that the
1056 * driver is doing some kind of reference counting. But that doesn't
1057 * really matter for the anon_vma sharing case.
1058 */
1059static int anon_vma_compatible(struct vm_area_struct *a, struct vm_area_struct *b)
1060{
1061 return a->vm_end == b->vm_start &&
1062 mpol_equal(vma_policy(a), vma_policy(b)) &&
1063 a->vm_file == b->vm_file &&
1064 !((a->vm_flags ^ b->vm_flags) & ~(VM_ACCESS_FLAGS | VM_SOFTDIRTY)) &&
1065 b->vm_pgoff == a->vm_pgoff + ((b->vm_start - a->vm_start) >> PAGE_SHIFT);
1066}
1067
1068/*
1069 * Do some basic sanity checking to see if we can re-use the anon_vma
1070 * from 'old'. The 'a'/'b' vma's are in VM order - one of them will be
1071 * the same as 'old', the other will be the new one that is trying
1072 * to share the anon_vma.
1073 *
1074 * NOTE! This runs with mmap_lock held for reading, so it is possible that
1075 * the anon_vma of 'old' is concurrently in the process of being set up
1076 * by another page fault trying to merge _that_. But that's ok: if it
1077 * is being set up, that automatically means that it will be a singleton
1078 * acceptable for merging, so we can do all of this optimistically. But
1079 * we do that READ_ONCE() to make sure that we never re-load the pointer.
1080 *
1081 * IOW: that the "list_is_singular()" test on the anon_vma_chain only
1082 * matters for the 'stable anon_vma' case (ie the thing we want to avoid
1083 * is to return an anon_vma that is "complex" due to having gone through
1084 * a fork).
1085 *
1086 * We also make sure that the two vma's are compatible (adjacent,
1087 * and with the same memory policies). That's all stable, even with just
1088 * a read lock on the mmap_lock.
1089 */
1090static struct anon_vma *reusable_anon_vma(struct vm_area_struct *old, struct vm_area_struct *a, struct vm_area_struct *b)
1091{
1092 if (anon_vma_compatible(a, b)) {
1093 struct anon_vma *anon_vma = READ_ONCE(old->anon_vma);
1094
1095 if (anon_vma && list_is_singular(head: &old->anon_vma_chain))
1096 return anon_vma;
1097 }
1098 return NULL;
1099}
1100
1101/*
1102 * find_mergeable_anon_vma is used by anon_vma_prepare, to check
1103 * neighbouring vmas for a suitable anon_vma, before it goes off
1104 * to allocate a new anon_vma. It checks because a repetitive
1105 * sequence of mprotects and faults may otherwise lead to distinct
1106 * anon_vmas being allocated, preventing vma merge in subsequent
1107 * mprotect.
1108 */
1109struct anon_vma *find_mergeable_anon_vma(struct vm_area_struct *vma)
1110{
1111 MA_STATE(mas, &vma->vm_mm->mm_mt, vma->vm_end, vma->vm_end);
1112 struct anon_vma *anon_vma = NULL;
1113 struct vm_area_struct *prev, *next;
1114
1115 /* Try next first. */
1116 next = mas_walk(mas: &mas);
1117 if (next) {
1118 anon_vma = reusable_anon_vma(old: next, a: vma, b: next);
1119 if (anon_vma)
1120 return anon_vma;
1121 }
1122
1123 prev = mas_prev(mas: &mas, min: 0);
1124 VM_BUG_ON_VMA(prev != vma, vma);
1125 prev = mas_prev(mas: &mas, min: 0);
1126 /* Try prev next. */
1127 if (prev)
1128 anon_vma = reusable_anon_vma(old: prev, a: prev, b: vma);
1129
1130 /*
1131 * We might reach here with anon_vma == NULL if we can't find
1132 * any reusable anon_vma.
1133 * There's no absolute need to look only at touching neighbours:
1134 * we could search further afield for "compatible" anon_vmas.
1135 * But it would probably just be a waste of time searching,
1136 * or lead to too many vmas hanging off the same anon_vma.
1137 * We're trying to allow mprotect remerging later on,
1138 * not trying to minimize memory used for anon_vmas.
1139 */
1140 return anon_vma;
1141}
1142
1143/*
1144 * If a hint addr is less than mmap_min_addr change hint to be as
1145 * low as possible but still greater than mmap_min_addr
1146 */
1147static inline unsigned long round_hint_to_min(unsigned long hint)
1148{
1149 hint &= PAGE_MASK;
1150 if (((void *)hint != NULL) &&
1151 (hint < mmap_min_addr))
1152 return PAGE_ALIGN(mmap_min_addr);
1153 return hint;
1154}
1155
1156bool mlock_future_ok(struct mm_struct *mm, unsigned long flags,
1157 unsigned long bytes)
1158{
1159 unsigned long locked_pages, limit_pages;
1160
1161 if (!(flags & VM_LOCKED) || capable(CAP_IPC_LOCK))
1162 return true;
1163
1164 locked_pages = bytes >> PAGE_SHIFT;
1165 locked_pages += mm->locked_vm;
1166
1167 limit_pages = rlimit(RLIMIT_MEMLOCK);
1168 limit_pages >>= PAGE_SHIFT;
1169
1170 return locked_pages <= limit_pages;
1171}
1172
1173static inline u64 file_mmap_size_max(struct file *file, struct inode *inode)
1174{
1175 if (S_ISREG(inode->i_mode))
1176 return MAX_LFS_FILESIZE;
1177
1178 if (S_ISBLK(inode->i_mode))
1179 return MAX_LFS_FILESIZE;
1180
1181 if (S_ISSOCK(inode->i_mode))
1182 return MAX_LFS_FILESIZE;
1183
1184 /* Special "we do even unsigned file positions" case */
1185 if (file->f_mode & FMODE_UNSIGNED_OFFSET)
1186 return 0;
1187
1188 /* Yes, random drivers might want more. But I'm tired of buggy drivers */
1189 return ULONG_MAX;
1190}
1191
1192static inline bool file_mmap_ok(struct file *file, struct inode *inode,
1193 unsigned long pgoff, unsigned long len)
1194{
1195 u64 maxsize = file_mmap_size_max(file, inode);
1196
1197 if (maxsize && len > maxsize)
1198 return false;
1199 maxsize -= len;
1200 if (pgoff > maxsize >> PAGE_SHIFT)
1201 return false;
1202 return true;
1203}
1204
1205/*
1206 * The caller must write-lock current->mm->mmap_lock.
1207 */
1208unsigned long do_mmap(struct file *file, unsigned long addr,
1209 unsigned long len, unsigned long prot,
1210 unsigned long flags, vm_flags_t vm_flags,
1211 unsigned long pgoff, unsigned long *populate,
1212 struct list_head *uf)
1213{
1214 struct mm_struct *mm = current->mm;
1215 int pkey = 0;
1216
1217 *populate = 0;
1218
1219 if (!len)
1220 return -EINVAL;
1221
1222 /*
1223 * Does the application expect PROT_READ to imply PROT_EXEC?
1224 *
1225 * (the exception is when the underlying filesystem is noexec
1226 * mounted, in which case we don't add PROT_EXEC.)
1227 */
1228 if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
1229 if (!(file && path_noexec(path: &file->f_path)))
1230 prot |= PROT_EXEC;
1231
1232 /* force arch specific MAP_FIXED handling in get_unmapped_area */
1233 if (flags & MAP_FIXED_NOREPLACE)
1234 flags |= MAP_FIXED;
1235
1236 if (!(flags & MAP_FIXED))
1237 addr = round_hint_to_min(hint: addr);
1238
1239 /* Careful about overflows.. */
1240 len = PAGE_ALIGN(len);
1241 if (!len)
1242 return -ENOMEM;
1243
1244 /* offset overflow? */
1245 if ((pgoff + (len >> PAGE_SHIFT)) < pgoff)
1246 return -EOVERFLOW;
1247
1248 /* Too many mappings? */
1249 if (mm->map_count > sysctl_max_map_count)
1250 return -ENOMEM;
1251
1252 /* Obtain the address to map to. we verify (or select) it and ensure
1253 * that it represents a valid section of the address space.
1254 */
1255 addr = get_unmapped_area(file, addr, len, pgoff, flags);
1256 if (IS_ERR_VALUE(addr))
1257 return addr;
1258
1259 if (flags & MAP_FIXED_NOREPLACE) {
1260 if (find_vma_intersection(mm, start_addr: addr, end_addr: addr + len))
1261 return -EEXIST;
1262 }
1263
1264 if (prot == PROT_EXEC) {
1265 pkey = execute_only_pkey(mm);
1266 if (pkey < 0)
1267 pkey = 0;
1268 }
1269
1270 /* Do simple checking here so the lower-level routines won't have
1271 * to. we assume access permissions have been handled by the open
1272 * of the memory object, so we don't do any here.
1273 */
1274 vm_flags |= calc_vm_prot_bits(prot, pkey) | calc_vm_flag_bits(flags) |
1275 mm->def_flags | VM_MAYREAD | VM_MAYWRITE | VM_MAYEXEC;
1276
1277 if (flags & MAP_LOCKED)
1278 if (!can_do_mlock())
1279 return -EPERM;
1280
1281 if (!mlock_future_ok(mm, flags: vm_flags, bytes: len))
1282 return -EAGAIN;
1283
1284 if (file) {
1285 struct inode *inode = file_inode(f: file);
1286 unsigned long flags_mask;
1287
1288 if (!file_mmap_ok(file, inode, pgoff, len))
1289 return -EOVERFLOW;
1290
1291 flags_mask = LEGACY_MAP_MASK | file->f_op->mmap_supported_flags;
1292
1293 switch (flags & MAP_TYPE) {
1294 case MAP_SHARED:
1295 /*
1296 * Force use of MAP_SHARED_VALIDATE with non-legacy
1297 * flags. E.g. MAP_SYNC is dangerous to use with
1298 * MAP_SHARED as you don't know which consistency model
1299 * you will get. We silently ignore unsupported flags
1300 * with MAP_SHARED to preserve backward compatibility.
1301 */
1302 flags &= LEGACY_MAP_MASK;
1303 fallthrough;
1304 case MAP_SHARED_VALIDATE:
1305 if (flags & ~flags_mask)
1306 return -EOPNOTSUPP;
1307 if (prot & PROT_WRITE) {
1308 if (!(file->f_mode & FMODE_WRITE))
1309 return -EACCES;
1310 if (IS_SWAPFILE(file->f_mapping->host))
1311 return -ETXTBSY;
1312 }
1313
1314 /*
1315 * Make sure we don't allow writing to an append-only
1316 * file..
1317 */
1318 if (IS_APPEND(inode) && (file->f_mode & FMODE_WRITE))
1319 return -EACCES;
1320
1321 vm_flags |= VM_SHARED | VM_MAYSHARE;
1322 if (!(file->f_mode & FMODE_WRITE))
1323 vm_flags &= ~(VM_MAYWRITE | VM_SHARED);
1324 fallthrough;
1325 case MAP_PRIVATE:
1326 if (!(file->f_mode & FMODE_READ))
1327 return -EACCES;
1328 if (path_noexec(path: &file->f_path)) {
1329 if (vm_flags & VM_EXEC)
1330 return -EPERM;
1331 vm_flags &= ~VM_MAYEXEC;
1332 }
1333
1334 if (!file->f_op->mmap)
1335 return -ENODEV;
1336 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1337 return -EINVAL;
1338 break;
1339
1340 default:
1341 return -EINVAL;
1342 }
1343 } else {
1344 switch (flags & MAP_TYPE) {
1345 case MAP_SHARED:
1346 if (vm_flags & (VM_GROWSDOWN|VM_GROWSUP))
1347 return -EINVAL;
1348 /*
1349 * Ignore pgoff.
1350 */
1351 pgoff = 0;
1352 vm_flags |= VM_SHARED | VM_MAYSHARE;
1353 break;
1354 case MAP_PRIVATE:
1355 /*
1356 * Set pgoff according to addr for anon_vma.
1357 */
1358 pgoff = addr >> PAGE_SHIFT;
1359 break;
1360 default:
1361 return -EINVAL;
1362 }
1363 }
1364
1365 /*
1366 * Set 'VM_NORESERVE' if we should not account for the
1367 * memory use of this mapping.
1368 */
1369 if (flags & MAP_NORESERVE) {
1370 /* We honor MAP_NORESERVE if allowed to overcommit */
1371 if (sysctl_overcommit_memory != OVERCOMMIT_NEVER)
1372 vm_flags |= VM_NORESERVE;
1373
1374 /* hugetlb applies strict overcommit unless MAP_NORESERVE */
1375 if (file && is_file_hugepages(file))
1376 vm_flags |= VM_NORESERVE;
1377 }
1378
1379 addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
1380 if (!IS_ERR_VALUE(addr) &&
1381 ((vm_flags & VM_LOCKED) ||
1382 (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
1383 *populate = len;
1384 return addr;
1385}
1386
1387unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len,
1388 unsigned long prot, unsigned long flags,
1389 unsigned long fd, unsigned long pgoff)
1390{
1391 struct file *file = NULL;
1392 unsigned long retval;
1393
1394 if (!(flags & MAP_ANONYMOUS)) {
1395 audit_mmap_fd(fd, flags);
1396 file = fget(fd);
1397 if (!file)
1398 return -EBADF;
1399 if (is_file_hugepages(file)) {
1400 len = ALIGN(len, huge_page_size(hstate_file(file)));
1401 } else if (unlikely(flags & MAP_HUGETLB)) {
1402 retval = -EINVAL;
1403 goto out_fput;
1404 }
1405 } else if (flags & MAP_HUGETLB) {
1406 struct hstate *hs;
1407
1408 hs = hstate_sizelog(page_size_log: (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1409 if (!hs)
1410 return -EINVAL;
1411
1412 len = ALIGN(len, huge_page_size(hs));
1413 /*
1414 * VM_NORESERVE is used because the reservations will be
1415 * taken when vm_ops->mmap() is called
1416 */
1417 file = hugetlb_file_setup(HUGETLB_ANON_FILE, size: len,
1418 VM_NORESERVE,
1419 creat_flags: HUGETLB_ANONHUGE_INODE,
1420 page_size_log: (flags >> MAP_HUGE_SHIFT) & MAP_HUGE_MASK);
1421 if (IS_ERR(ptr: file))
1422 return PTR_ERR(ptr: file);
1423 }
1424
1425 retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff);
1426out_fput:
1427 if (file)
1428 fput(file);
1429 return retval;
1430}
1431
1432SYSCALL_DEFINE6(mmap_pgoff, unsigned long, addr, unsigned long, len,
1433 unsigned long, prot, unsigned long, flags,
1434 unsigned long, fd, unsigned long, pgoff)
1435{
1436 return ksys_mmap_pgoff(addr, len, prot, flags, fd, pgoff);
1437}
1438
1439#ifdef __ARCH_WANT_SYS_OLD_MMAP
1440struct mmap_arg_struct {
1441 unsigned long addr;
1442 unsigned long len;
1443 unsigned long prot;
1444 unsigned long flags;
1445 unsigned long fd;
1446 unsigned long offset;
1447};
1448
1449SYSCALL_DEFINE1(old_mmap, struct mmap_arg_struct __user *, arg)
1450{
1451 struct mmap_arg_struct a;
1452
1453 if (copy_from_user(&a, arg, sizeof(a)))
1454 return -EFAULT;
1455 if (offset_in_page(a.offset))
1456 return -EINVAL;
1457
1458 return ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd,
1459 a.offset >> PAGE_SHIFT);
1460}
1461#endif /* __ARCH_WANT_SYS_OLD_MMAP */
1462
1463static bool vm_ops_needs_writenotify(const struct vm_operations_struct *vm_ops)
1464{
1465 return vm_ops && (vm_ops->page_mkwrite || vm_ops->pfn_mkwrite);
1466}
1467
1468static bool vma_is_shared_writable(struct vm_area_struct *vma)
1469{
1470 return (vma->vm_flags & (VM_WRITE | VM_SHARED)) ==
1471 (VM_WRITE | VM_SHARED);
1472}
1473
1474static bool vma_fs_can_writeback(struct vm_area_struct *vma)
1475{
1476 /* No managed pages to writeback. */
1477 if (vma->vm_flags & VM_PFNMAP)
1478 return false;
1479
1480 return vma->vm_file && vma->vm_file->f_mapping &&
1481 mapping_can_writeback(mapping: vma->vm_file->f_mapping);
1482}
1483
1484/*
1485 * Does this VMA require the underlying folios to have their dirty state
1486 * tracked?
1487 */
1488bool vma_needs_dirty_tracking(struct vm_area_struct *vma)
1489{
1490 /* Only shared, writable VMAs require dirty tracking. */
1491 if (!vma_is_shared_writable(vma))
1492 return false;
1493
1494 /* Does the filesystem need to be notified? */
1495 if (vm_ops_needs_writenotify(vm_ops: vma->vm_ops))
1496 return true;
1497
1498 /*
1499 * Even if the filesystem doesn't indicate a need for writenotify, if it
1500 * can writeback, dirty tracking is still required.
1501 */
1502 return vma_fs_can_writeback(vma);
1503}
1504
1505/*
1506 * Some shared mappings will want the pages marked read-only
1507 * to track write events. If so, we'll downgrade vm_page_prot
1508 * to the private version (using protection_map[] without the
1509 * VM_SHARED bit).
1510 */
1511int vma_wants_writenotify(struct vm_area_struct *vma, pgprot_t vm_page_prot)
1512{
1513 /* If it was private or non-writable, the write bit is already clear */
1514 if (!vma_is_shared_writable(vma))
1515 return 0;
1516
1517 /* The backer wishes to know when pages are first written to? */
1518 if (vm_ops_needs_writenotify(vm_ops: vma->vm_ops))
1519 return 1;
1520
1521 /* The open routine did something to the protections that pgprot_modify
1522 * won't preserve? */
1523 if (pgprot_val(vm_page_prot) !=
1524 pgprot_val(vm_pgprot_modify(vm_page_prot, vma->vm_flags)))
1525 return 0;
1526
1527 /*
1528 * Do we need to track softdirty? hugetlb does not support softdirty
1529 * tracking yet.
1530 */
1531 if (vma_soft_dirty_enabled(vma) && !is_vm_hugetlb_page(vma))
1532 return 1;
1533
1534 /* Do we need write faults for uffd-wp tracking? */
1535 if (userfaultfd_wp(vma))
1536 return 1;
1537
1538 /* Can the mapping track the dirty pages? */
1539 return vma_fs_can_writeback(vma);
1540}
1541
1542/*
1543 * We account for memory if it's a private writeable mapping,
1544 * not hugepages and VM_NORESERVE wasn't set.
1545 */
1546static inline int accountable_mapping(struct file *file, vm_flags_t vm_flags)
1547{
1548 /*
1549 * hugetlb has its own accounting separate from the core VM
1550 * VM_HUGETLB may not be set yet so we cannot check for that flag.
1551 */
1552 if (file && is_file_hugepages(file))
1553 return 0;
1554
1555 return (vm_flags & (VM_NORESERVE | VM_SHARED | VM_WRITE)) == VM_WRITE;
1556}
1557
1558/**
1559 * unmapped_area() - Find an area between the low_limit and the high_limit with
1560 * the correct alignment and offset, all from @info. Note: current->mm is used
1561 * for the search.
1562 *
1563 * @info: The unmapped area information including the range [low_limit -
1564 * high_limit), the alignment offset and mask.
1565 *
1566 * Return: A memory address or -ENOMEM.
1567 */
1568static unsigned long unmapped_area(struct vm_unmapped_area_info *info)
1569{
1570 unsigned long length, gap;
1571 unsigned long low_limit, high_limit;
1572 struct vm_area_struct *tmp;
1573
1574 MA_STATE(mas, &current->mm->mm_mt, 0, 0);
1575
1576 /* Adjust search length to account for worst case alignment overhead */
1577 length = info->length + info->align_mask;
1578 if (length < info->length)
1579 return -ENOMEM;
1580
1581 low_limit = info->low_limit;
1582 if (low_limit < mmap_min_addr)
1583 low_limit = mmap_min_addr;
1584 high_limit = info->high_limit;
1585retry:
1586 if (mas_empty_area(mas: &mas, min: low_limit, max: high_limit - 1, size: length))
1587 return -ENOMEM;
1588
1589 gap = mas.index;
1590 gap += (info->align_offset - gap) & info->align_mask;
1591 tmp = mas_next(mas: &mas, ULONG_MAX);
1592 if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
1593 if (vm_start_gap(vma: tmp) < gap + length - 1) {
1594 low_limit = tmp->vm_end;
1595 mas_reset(mas: &mas);
1596 goto retry;
1597 }
1598 } else {
1599 tmp = mas_prev(mas: &mas, min: 0);
1600 if (tmp && vm_end_gap(vma: tmp) > gap) {
1601 low_limit = vm_end_gap(vma: tmp);
1602 mas_reset(mas: &mas);
1603 goto retry;
1604 }
1605 }
1606
1607 return gap;
1608}
1609
1610/**
1611 * unmapped_area_topdown() - Find an area between the low_limit and the
1612 * high_limit with the correct alignment and offset at the highest available
1613 * address, all from @info. Note: current->mm is used for the search.
1614 *
1615 * @info: The unmapped area information including the range [low_limit -
1616 * high_limit), the alignment offset and mask.
1617 *
1618 * Return: A memory address or -ENOMEM.
1619 */
1620static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
1621{
1622 unsigned long length, gap, gap_end;
1623 unsigned long low_limit, high_limit;
1624 struct vm_area_struct *tmp;
1625
1626 MA_STATE(mas, &current->mm->mm_mt, 0, 0);
1627 /* Adjust search length to account for worst case alignment overhead */
1628 length = info->length + info->align_mask;
1629 if (length < info->length)
1630 return -ENOMEM;
1631
1632 low_limit = info->low_limit;
1633 if (low_limit < mmap_min_addr)
1634 low_limit = mmap_min_addr;
1635 high_limit = info->high_limit;
1636retry:
1637 if (mas_empty_area_rev(mas: &mas, min: low_limit, max: high_limit - 1, size: length))
1638 return -ENOMEM;
1639
1640 gap = mas.last + 1 - info->length;
1641 gap -= (gap - info->align_offset) & info->align_mask;
1642 gap_end = mas.last;
1643 tmp = mas_next(mas: &mas, ULONG_MAX);
1644 if (tmp && (tmp->vm_flags & VM_STARTGAP_FLAGS)) { /* Avoid prev check if possible */
1645 if (vm_start_gap(vma: tmp) <= gap_end) {
1646 high_limit = vm_start_gap(vma: tmp);
1647 mas_reset(mas: &mas);
1648 goto retry;
1649 }
1650 } else {
1651 tmp = mas_prev(mas: &mas, min: 0);
1652 if (tmp && vm_end_gap(vma: tmp) > gap) {
1653 high_limit = tmp->vm_start;
1654 mas_reset(mas: &mas);
1655 goto retry;
1656 }
1657 }
1658
1659 return gap;
1660}
1661
1662/*
1663 * Search for an unmapped address range.
1664 *
1665 * We are looking for a range that:
1666 * - does not intersect with any VMA;
1667 * - is contained within the [low_limit, high_limit) interval;
1668 * - is at least the desired size.
1669 * - satisfies (begin_addr & align_mask) == (align_offset & align_mask)
1670 */
1671unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
1672{
1673 unsigned long addr;
1674
1675 if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
1676 addr = unmapped_area_topdown(info);
1677 else
1678 addr = unmapped_area(info);
1679
1680 trace_vm_unmapped_area(addr, info);
1681 return addr;
1682}
1683
1684/* Get an address range which is currently unmapped.
1685 * For shmat() with addr=0.
1686 *
1687 * Ugly calling convention alert:
1688 * Return value with the low bits set means error value,
1689 * ie
1690 * if (ret & ~PAGE_MASK)
1691 * error = ret;
1692 *
1693 * This function "knows" that -ENOMEM has the bits set.
1694 */
1695unsigned long
1696generic_get_unmapped_area(struct file *filp, unsigned long addr,
1697 unsigned long len, unsigned long pgoff,
1698 unsigned long flags)
1699{
1700 struct mm_struct *mm = current->mm;
1701 struct vm_area_struct *vma, *prev;
1702 struct vm_unmapped_area_info info;
1703 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
1704
1705 if (len > mmap_end - mmap_min_addr)
1706 return -ENOMEM;
1707
1708 if (flags & MAP_FIXED)
1709 return addr;
1710
1711 if (addr) {
1712 addr = PAGE_ALIGN(addr);
1713 vma = find_vma_prev(mm, addr, pprev: &prev);
1714 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
1715 (!vma || addr + len <= vm_start_gap(vma)) &&
1716 (!prev || addr >= vm_end_gap(vma: prev)))
1717 return addr;
1718 }
1719
1720 info.flags = 0;
1721 info.length = len;
1722 info.low_limit = mm->mmap_base;
1723 info.high_limit = mmap_end;
1724 info.align_mask = 0;
1725 info.align_offset = 0;
1726 return vm_unmapped_area(info: &info);
1727}
1728
1729#ifndef HAVE_ARCH_UNMAPPED_AREA
1730unsigned long
1731arch_get_unmapped_area(struct file *filp, unsigned long addr,
1732 unsigned long len, unsigned long pgoff,
1733 unsigned long flags)
1734{
1735 return generic_get_unmapped_area(filp, addr, len, pgoff, flags);
1736}
1737#endif
1738
1739/*
1740 * This mmap-allocator allocates new areas top-down from below the
1741 * stack's low limit (the base):
1742 */
1743unsigned long
1744generic_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
1745 unsigned long len, unsigned long pgoff,
1746 unsigned long flags)
1747{
1748 struct vm_area_struct *vma, *prev;
1749 struct mm_struct *mm = current->mm;
1750 struct vm_unmapped_area_info info;
1751 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
1752
1753 /* requested length too big for entire address space */
1754 if (len > mmap_end - mmap_min_addr)
1755 return -ENOMEM;
1756
1757 if (flags & MAP_FIXED)
1758 return addr;
1759
1760 /* requesting a specific address */
1761 if (addr) {
1762 addr = PAGE_ALIGN(addr);
1763 vma = find_vma_prev(mm, addr, pprev: &prev);
1764 if (mmap_end - len >= addr && addr >= mmap_min_addr &&
1765 (!vma || addr + len <= vm_start_gap(vma)) &&
1766 (!prev || addr >= vm_end_gap(vma: prev)))
1767 return addr;
1768 }
1769
1770 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
1771 info.length = len;
1772 info.low_limit = PAGE_SIZE;
1773 info.high_limit = arch_get_mmap_base(addr, mm->mmap_base);
1774 info.align_mask = 0;
1775 info.align_offset = 0;
1776 addr = vm_unmapped_area(info: &info);
1777
1778 /*
1779 * A failed mmap() very likely causes application failure,
1780 * so fall back to the bottom-up function here. This scenario
1781 * can happen with large stack limits and large mmap()
1782 * allocations.
1783 */
1784 if (offset_in_page(addr)) {
1785 VM_BUG_ON(addr != -ENOMEM);
1786 info.flags = 0;
1787 info.low_limit = TASK_UNMAPPED_BASE;
1788 info.high_limit = mmap_end;
1789 addr = vm_unmapped_area(info: &info);
1790 }
1791
1792 return addr;
1793}
1794
1795#ifndef HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
1796unsigned long
1797arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
1798 unsigned long len, unsigned long pgoff,
1799 unsigned long flags)
1800{
1801 return generic_get_unmapped_area_topdown(filp, addr, len, pgoff, flags);
1802}
1803#endif
1804
1805unsigned long
1806get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
1807 unsigned long pgoff, unsigned long flags)
1808{
1809 unsigned long (*get_area)(struct file *, unsigned long,
1810 unsigned long, unsigned long, unsigned long);
1811
1812 unsigned long error = arch_mmap_check(addr, len, flags);
1813 if (error)
1814 return error;
1815
1816 /* Careful about overflows.. */
1817 if (len > TASK_SIZE)
1818 return -ENOMEM;
1819
1820 get_area = current->mm->get_unmapped_area;
1821 if (file) {
1822 if (file->f_op->get_unmapped_area)
1823 get_area = file->f_op->get_unmapped_area;
1824 } else if (flags & MAP_SHARED) {
1825 /*
1826 * mmap_region() will call shmem_zero_setup() to create a file,
1827 * so use shmem's get_unmapped_area in case it can be huge.
1828 * do_mmap() will clear pgoff, so match alignment.
1829 */
1830 pgoff = 0;
1831 get_area = shmem_get_unmapped_area;
1832 }
1833
1834 addr = get_area(file, addr, len, pgoff, flags);
1835 if (IS_ERR_VALUE(addr))
1836 return addr;
1837
1838 if (addr > TASK_SIZE - len)
1839 return -ENOMEM;
1840 if (offset_in_page(addr))
1841 return -EINVAL;
1842
1843 error = security_mmap_addr(addr);
1844 return error ? error : addr;
1845}
1846
1847EXPORT_SYMBOL(get_unmapped_area);
1848
1849/**
1850 * find_vma_intersection() - Look up the first VMA which intersects the interval
1851 * @mm: The process address space.
1852 * @start_addr: The inclusive start user address.
1853 * @end_addr: The exclusive end user address.
1854 *
1855 * Returns: The first VMA within the provided range, %NULL otherwise. Assumes
1856 * start_addr < end_addr.
1857 */
1858struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
1859 unsigned long start_addr,
1860 unsigned long end_addr)
1861{
1862 unsigned long index = start_addr;
1863
1864 mmap_assert_locked(mm);
1865 return mt_find(mt: &mm->mm_mt, index: &index, max: end_addr - 1);
1866}
1867EXPORT_SYMBOL(find_vma_intersection);
1868
1869/**
1870 * find_vma() - Find the VMA for a given address, or the next VMA.
1871 * @mm: The mm_struct to check
1872 * @addr: The address
1873 *
1874 * Returns: The VMA associated with addr, or the next VMA.
1875 * May return %NULL in the case of no VMA at addr or above.
1876 */
1877struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
1878{
1879 unsigned long index = addr;
1880
1881 mmap_assert_locked(mm);
1882 return mt_find(mt: &mm->mm_mt, index: &index, ULONG_MAX);
1883}
1884EXPORT_SYMBOL(find_vma);
1885
1886/**
1887 * find_vma_prev() - Find the VMA for a given address, or the next vma and
1888 * set %pprev to the previous VMA, if any.
1889 * @mm: The mm_struct to check
1890 * @addr: The address
1891 * @pprev: The pointer to set to the previous VMA
1892 *
1893 * Note that RCU lock is missing here since the external mmap_lock() is used
1894 * instead.
1895 *
1896 * Returns: The VMA associated with @addr, or the next vma.
1897 * May return %NULL in the case of no vma at addr or above.
1898 */
1899struct vm_area_struct *
1900find_vma_prev(struct mm_struct *mm, unsigned long addr,
1901 struct vm_area_struct **pprev)
1902{
1903 struct vm_area_struct *vma;
1904 MA_STATE(mas, &mm->mm_mt, addr, addr);
1905
1906 vma = mas_walk(mas: &mas);
1907 *pprev = mas_prev(mas: &mas, min: 0);
1908 if (!vma)
1909 vma = mas_next(mas: &mas, ULONG_MAX);
1910 return vma;
1911}
1912
1913/*
1914 * Verify that the stack growth is acceptable and
1915 * update accounting. This is shared with both the
1916 * grow-up and grow-down cases.
1917 */
1918static int acct_stack_growth(struct vm_area_struct *vma,
1919 unsigned long size, unsigned long grow)
1920{
1921 struct mm_struct *mm = vma->vm_mm;
1922 unsigned long new_start;
1923
1924 /* address space limit tests */
1925 if (!may_expand_vm(mm, vma->vm_flags, npages: grow))
1926 return -ENOMEM;
1927
1928 /* Stack limit test */
1929 if (size > rlimit(RLIMIT_STACK))
1930 return -ENOMEM;
1931
1932 /* mlock limit tests */
1933 if (!mlock_future_ok(mm, flags: vma->vm_flags, bytes: grow << PAGE_SHIFT))
1934 return -ENOMEM;
1935
1936 /* Check to ensure the stack will not grow into a hugetlb-only region */
1937 new_start = (vma->vm_flags & VM_GROWSUP) ? vma->vm_start :
1938 vma->vm_end - size;
1939 if (is_hugepage_only_range(mm: vma->vm_mm, addr: new_start, len: size))
1940 return -EFAULT;
1941
1942 /*
1943 * Overcommit.. This must be the final test, as it will
1944 * update security statistics.
1945 */
1946 if (security_vm_enough_memory_mm(mm, pages: grow))
1947 return -ENOMEM;
1948
1949 return 0;
1950}
1951
1952#if defined(CONFIG_STACK_GROWSUP)
1953/*
1954 * PA-RISC uses this for its stack.
1955 * vma is the last one with address > vma->vm_end. Have to extend vma.
1956 */
1957static int expand_upwards(struct vm_area_struct *vma, unsigned long address)
1958{
1959 struct mm_struct *mm = vma->vm_mm;
1960 struct vm_area_struct *next;
1961 unsigned long gap_addr;
1962 int error = 0;
1963 MA_STATE(mas, &mm->mm_mt, vma->vm_start, address);
1964
1965 if (!(vma->vm_flags & VM_GROWSUP))
1966 return -EFAULT;
1967
1968 /* Guard against exceeding limits of the address space. */
1969 address &= PAGE_MASK;
1970 if (address >= (TASK_SIZE & PAGE_MASK))
1971 return -ENOMEM;
1972 address += PAGE_SIZE;
1973
1974 /* Enforce stack_guard_gap */
1975 gap_addr = address + stack_guard_gap;
1976
1977 /* Guard against overflow */
1978 if (gap_addr < address || gap_addr > TASK_SIZE)
1979 gap_addr = TASK_SIZE;
1980
1981 next = find_vma_intersection(mm, vma->vm_end, gap_addr);
1982 if (next && vma_is_accessible(next)) {
1983 if (!(next->vm_flags & VM_GROWSUP))
1984 return -ENOMEM;
1985 /* Check that both stack segments have the same anon_vma? */
1986 }
1987
1988 if (next)
1989 mas_prev_range(&mas, address);
1990
1991 __mas_set_range(&mas, vma->vm_start, address - 1);
1992 if (mas_preallocate(&mas, vma, GFP_KERNEL))
1993 return -ENOMEM;
1994
1995 /* We must make sure the anon_vma is allocated. */
1996 if (unlikely(anon_vma_prepare(vma))) {
1997 mas_destroy(&mas);
1998 return -ENOMEM;
1999 }
2000
2001 /* Lock the VMA before expanding to prevent concurrent page faults */
2002 vma_start_write(vma);
2003 /*
2004 * vma->vm_start/vm_end cannot change under us because the caller
2005 * is required to hold the mmap_lock in read mode. We need the
2006 * anon_vma lock to serialize against concurrent expand_stacks.
2007 */
2008 anon_vma_lock_write(vma->anon_vma);
2009
2010 /* Somebody else might have raced and expanded it already */
2011 if (address > vma->vm_end) {
2012 unsigned long size, grow;
2013
2014 size = address - vma->vm_start;
2015 grow = (address - vma->vm_end) >> PAGE_SHIFT;
2016
2017 error = -ENOMEM;
2018 if (vma->vm_pgoff + (size >> PAGE_SHIFT) >= vma->vm_pgoff) {
2019 error = acct_stack_growth(vma, size, grow);
2020 if (!error) {
2021 /*
2022 * We only hold a shared mmap_lock lock here, so
2023 * we need to protect against concurrent vma
2024 * expansions. anon_vma_lock_write() doesn't
2025 * help here, as we don't guarantee that all
2026 * growable vmas in a mm share the same root
2027 * anon vma. So, we reuse mm->page_table_lock
2028 * to guard against concurrent vma expansions.
2029 */
2030 spin_lock(&mm->page_table_lock);
2031 if (vma->vm_flags & VM_LOCKED)
2032 mm->locked_vm += grow;
2033 vm_stat_account(mm, vma->vm_flags, grow);
2034 anon_vma_interval_tree_pre_update_vma(vma);
2035 vma->vm_end = address;
2036 /* Overwrite old entry in mtree. */
2037 mas_store_prealloc(&mas, vma);
2038 anon_vma_interval_tree_post_update_vma(vma);
2039 spin_unlock(&mm->page_table_lock);
2040
2041 perf_event_mmap(vma);
2042 }
2043 }
2044 }
2045 anon_vma_unlock_write(vma->anon_vma);
2046 khugepaged_enter_vma(vma, vma->vm_flags);
2047 mas_destroy(&mas);
2048 validate_mm(mm);
2049 return error;
2050}
2051#endif /* CONFIG_STACK_GROWSUP */
2052
2053/*
2054 * vma is the first one with address < vma->vm_start. Have to extend vma.
2055 * mmap_lock held for writing.
2056 */
2057int expand_downwards(struct vm_area_struct *vma, unsigned long address)
2058{
2059 struct mm_struct *mm = vma->vm_mm;
2060 MA_STATE(mas, &mm->mm_mt, vma->vm_start, vma->vm_start);
2061 struct vm_area_struct *prev;
2062 int error = 0;
2063
2064 if (!(vma->vm_flags & VM_GROWSDOWN))
2065 return -EFAULT;
2066
2067 address &= PAGE_MASK;
2068 if (address < mmap_min_addr || address < FIRST_USER_ADDRESS)
2069 return -EPERM;
2070
2071 /* Enforce stack_guard_gap */
2072 prev = mas_prev(mas: &mas, min: 0);
2073 /* Check that both stack segments have the same anon_vma? */
2074 if (prev) {
2075 if (!(prev->vm_flags & VM_GROWSDOWN) &&
2076 vma_is_accessible(vma: prev) &&
2077 (address - prev->vm_end < stack_guard_gap))
2078 return -ENOMEM;
2079 }
2080
2081 if (prev)
2082 mas_next_range(mas: &mas, max: vma->vm_start);
2083
2084 __mas_set_range(mas: &mas, start: address, last: vma->vm_end - 1);
2085 if (mas_preallocate(mas: &mas, entry: vma, GFP_KERNEL))
2086 return -ENOMEM;
2087
2088 /* We must make sure the anon_vma is allocated. */
2089 if (unlikely(anon_vma_prepare(vma))) {
2090 mas_destroy(mas: &mas);
2091 return -ENOMEM;
2092 }
2093
2094 /* Lock the VMA before expanding to prevent concurrent page faults */
2095 vma_start_write(vma);
2096 /*
2097 * vma->vm_start/vm_end cannot change under us because the caller
2098 * is required to hold the mmap_lock in read mode. We need the
2099 * anon_vma lock to serialize against concurrent expand_stacks.
2100 */
2101 anon_vma_lock_write(anon_vma: vma->anon_vma);
2102
2103 /* Somebody else might have raced and expanded it already */
2104 if (address < vma->vm_start) {
2105 unsigned long size, grow;
2106
2107 size = vma->vm_end - address;
2108 grow = (vma->vm_start - address) >> PAGE_SHIFT;
2109
2110 error = -ENOMEM;
2111 if (grow <= vma->vm_pgoff) {
2112 error = acct_stack_growth(vma, size, grow);
2113 if (!error) {
2114 /*
2115 * We only hold a shared mmap_lock lock here, so
2116 * we need to protect against concurrent vma
2117 * expansions. anon_vma_lock_write() doesn't
2118 * help here, as we don't guarantee that all
2119 * growable vmas in a mm share the same root
2120 * anon vma. So, we reuse mm->page_table_lock
2121 * to guard against concurrent vma expansions.
2122 */
2123 spin_lock(lock: &mm->page_table_lock);
2124 if (vma->vm_flags & VM_LOCKED)
2125 mm->locked_vm += grow;
2126 vm_stat_account(mm, vma->vm_flags, npages: grow);
2127 anon_vma_interval_tree_pre_update_vma(vma);
2128 vma->vm_start = address;
2129 vma->vm_pgoff -= grow;
2130 /* Overwrite old entry in mtree. */
2131 mas_store_prealloc(mas: &mas, entry: vma);
2132 anon_vma_interval_tree_post_update_vma(vma);
2133 spin_unlock(lock: &mm->page_table_lock);
2134
2135 perf_event_mmap(vma);
2136 }
2137 }
2138 }
2139 anon_vma_unlock_write(anon_vma: vma->anon_vma);
2140 khugepaged_enter_vma(vma, vm_flags: vma->vm_flags);
2141 mas_destroy(mas: &mas);
2142 validate_mm(mm);
2143 return error;
2144}
2145
2146/* enforced gap between the expanding stack and other mappings. */
2147unsigned long stack_guard_gap = 256UL<<PAGE_SHIFT;
2148
2149static int __init cmdline_parse_stack_guard_gap(char *p)
2150{
2151 unsigned long val;
2152 char *endptr;
2153
2154 val = simple_strtoul(p, &endptr, 10);
2155 if (!*endptr)
2156 stack_guard_gap = val << PAGE_SHIFT;
2157
2158 return 1;
2159}
2160__setup("stack_guard_gap=", cmdline_parse_stack_guard_gap);
2161
2162#ifdef CONFIG_STACK_GROWSUP
2163int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
2164{
2165 return expand_upwards(vma, address);
2166}
2167
2168struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
2169{
2170 struct vm_area_struct *vma, *prev;
2171
2172 addr &= PAGE_MASK;
2173 vma = find_vma_prev(mm, addr, &prev);
2174 if (vma && (vma->vm_start <= addr))
2175 return vma;
2176 if (!prev)
2177 return NULL;
2178 if (expand_stack_locked(prev, addr))
2179 return NULL;
2180 if (prev->vm_flags & VM_LOCKED)
2181 populate_vma_page_range(prev, addr, prev->vm_end, NULL);
2182 return prev;
2183}
2184#else
2185int expand_stack_locked(struct vm_area_struct *vma, unsigned long address)
2186{
2187 return expand_downwards(vma, address);
2188}
2189
2190struct vm_area_struct *find_extend_vma_locked(struct mm_struct *mm, unsigned long addr)
2191{
2192 struct vm_area_struct *vma;
2193 unsigned long start;
2194
2195 addr &= PAGE_MASK;
2196 vma = find_vma(mm, addr);
2197 if (!vma)
2198 return NULL;
2199 if (vma->vm_start <= addr)
2200 return vma;
2201 start = vma->vm_start;
2202 if (expand_stack_locked(vma, address: addr))
2203 return NULL;
2204 if (vma->vm_flags & VM_LOCKED)
2205 populate_vma_page_range(vma, start: addr, end: start, NULL);
2206 return vma;
2207}
2208#endif
2209
2210/*
2211 * IA64 has some horrid mapping rules: it can expand both up and down,
2212 * but with various special rules.
2213 *
2214 * We'll get rid of this architecture eventually, so the ugliness is
2215 * temporary.
2216 */
2217#ifdef CONFIG_IA64
2218static inline bool vma_expand_ok(struct vm_area_struct *vma, unsigned long addr)
2219{
2220 return REGION_NUMBER(addr) == REGION_NUMBER(vma->vm_start) &&
2221 REGION_OFFSET(addr) < RGN_MAP_LIMIT;
2222}
2223
2224/*
2225 * IA64 stacks grow down, but there's a special register backing store
2226 * that can grow up. Only sequentially, though, so the new address must
2227 * match vm_end.
2228 */
2229static inline int vma_expand_up(struct vm_area_struct *vma, unsigned long addr)
2230{
2231 if (!vma_expand_ok(vma, addr))
2232 return -EFAULT;
2233 if (vma->vm_end != (addr & PAGE_MASK))
2234 return -EFAULT;
2235 return expand_upwards(vma, addr);
2236}
2237
2238static inline bool vma_expand_down(struct vm_area_struct *vma, unsigned long addr)
2239{
2240 if (!vma_expand_ok(vma, addr))
2241 return -EFAULT;
2242 return expand_downwards(vma, addr);
2243}
2244
2245#elif defined(CONFIG_STACK_GROWSUP)
2246
2247#define vma_expand_up(vma,addr) expand_upwards(vma, addr)
2248#define vma_expand_down(vma, addr) (-EFAULT)
2249
2250#else
2251
2252#define vma_expand_up(vma,addr) (-EFAULT)
2253#define vma_expand_down(vma, addr) expand_downwards(vma, addr)
2254
2255#endif
2256
2257/*
2258 * expand_stack(): legacy interface for page faulting. Don't use unless
2259 * you have to.
2260 *
2261 * This is called with the mm locked for reading, drops the lock, takes
2262 * the lock for writing, tries to look up a vma again, expands it if
2263 * necessary, and downgrades the lock to reading again.
2264 *
2265 * If no vma is found or it can't be expanded, it returns NULL and has
2266 * dropped the lock.
2267 */
2268struct vm_area_struct *expand_stack(struct mm_struct *mm, unsigned long addr)
2269{
2270 struct vm_area_struct *vma, *prev;
2271
2272 mmap_read_unlock(mm);
2273 if (mmap_write_lock_killable(mm))
2274 return NULL;
2275
2276 vma = find_vma_prev(mm, addr, pprev: &prev);
2277 if (vma && vma->vm_start <= addr)
2278 goto success;
2279
2280 if (prev && !vma_expand_up(prev, addr)) {
2281 vma = prev;
2282 goto success;
2283 }
2284
2285 if (vma && !vma_expand_down(vma, addr))
2286 goto success;
2287
2288 mmap_write_unlock(mm);
2289 return NULL;
2290
2291success:
2292 mmap_write_downgrade(mm);
2293 return vma;
2294}
2295
2296/*
2297 * Ok - we have the memory areas we should free on a maple tree so release them,
2298 * and do the vma updates.
2299 *
2300 * Called with the mm semaphore held.
2301 */
2302static inline void remove_mt(struct mm_struct *mm, struct ma_state *mas)
2303{
2304 unsigned long nr_accounted = 0;
2305 struct vm_area_struct *vma;
2306
2307 /* Update high watermark before we lower total_vm */
2308 update_hiwater_vm(mm);
2309 mas_for_each(mas, vma, ULONG_MAX) {
2310 long nrpages = vma_pages(vma);
2311
2312 if (vma->vm_flags & VM_ACCOUNT)
2313 nr_accounted += nrpages;
2314 vm_stat_account(mm, vma->vm_flags, npages: -nrpages);
2315 remove_vma(vma, unreachable: false);
2316 }
2317 vm_unacct_memory(pages: nr_accounted);
2318}
2319
2320/*
2321 * Get rid of page table information in the indicated region.
2322 *
2323 * Called with the mm semaphore held.
2324 */
2325static void unmap_region(struct mm_struct *mm, struct ma_state *mas,
2326 struct vm_area_struct *vma, struct vm_area_struct *prev,
2327 struct vm_area_struct *next, unsigned long start,
2328 unsigned long end, unsigned long tree_end, bool mm_wr_locked)
2329{
2330 struct mmu_gather tlb;
2331 unsigned long mt_start = mas->index;
2332
2333 lru_add_drain();
2334 tlb_gather_mmu(tlb: &tlb, mm);
2335 update_hiwater_rss(mm);
2336 unmap_vmas(tlb: &tlb, mas, start_vma: vma, start, end, tree_end, mm_wr_locked);
2337 mas_set(mas, index: mt_start);
2338 free_pgtables(tlb: &tlb, mas, start_vma: vma, floor: prev ? prev->vm_end : FIRST_USER_ADDRESS,
2339 ceiling: next ? next->vm_start : USER_PGTABLES_CEILING,
2340 mm_wr_locked);
2341 tlb_finish_mmu(tlb: &tlb);
2342}
2343
2344/*
2345 * __split_vma() bypasses sysctl_max_map_count checking. We use this where it
2346 * has already been checked or doesn't make sense to fail.
2347 * VMA Iterator will point to the end VMA.
2348 */
2349static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
2350 unsigned long addr, int new_below)
2351{
2352 struct vma_prepare vp;
2353 struct vm_area_struct *new;
2354 int err;
2355
2356 WARN_ON(vma->vm_start >= addr);
2357 WARN_ON(vma->vm_end <= addr);
2358
2359 if (vma->vm_ops && vma->vm_ops->may_split) {
2360 err = vma->vm_ops->may_split(vma, addr);
2361 if (err)
2362 return err;
2363 }
2364
2365 new = vm_area_dup(vma);
2366 if (!new)
2367 return -ENOMEM;
2368
2369 if (new_below) {
2370 new->vm_end = addr;
2371 } else {
2372 new->vm_start = addr;
2373 new->vm_pgoff += ((addr - vma->vm_start) >> PAGE_SHIFT);
2374 }
2375
2376 err = -ENOMEM;
2377 vma_iter_config(vmi, index: new->vm_start, last: new->vm_end);
2378 if (vma_iter_prealloc(vmi, vma: new))
2379 goto out_free_vma;
2380
2381 err = vma_dup_policy(src: vma, dst: new);
2382 if (err)
2383 goto out_free_vmi;
2384
2385 err = anon_vma_clone(new, vma);
2386 if (err)
2387 goto out_free_mpol;
2388
2389 if (new->vm_file)
2390 get_file(f: new->vm_file);
2391
2392 if (new->vm_ops && new->vm_ops->open)
2393 new->vm_ops->open(new);
2394
2395 vma_start_write(vma);
2396 vma_start_write(vma: new);
2397
2398 init_vma_prep(vp: &vp, vma);
2399 vp.insert = new;
2400 vma_prepare(vp: &vp);
2401 vma_adjust_trans_huge(vma, start: vma->vm_start, end: addr, adjust_next: 0);
2402
2403 if (new_below) {
2404 vma->vm_start = addr;
2405 vma->vm_pgoff += (addr - new->vm_start) >> PAGE_SHIFT;
2406 } else {
2407 vma->vm_end = addr;
2408 }
2409
2410 /* vma_complete stores the new vma */
2411 vma_complete(vp: &vp, vmi, mm: vma->vm_mm);
2412
2413 /* Success. */
2414 if (new_below)
2415 vma_next(vmi);
2416 return 0;
2417
2418out_free_mpol:
2419 mpol_put(vma_policy(new));
2420out_free_vmi:
2421 vma_iter_free(vmi);
2422out_free_vma:
2423 vm_area_free(new);
2424 return err;
2425}
2426
2427/*
2428 * Split a vma into two pieces at address 'addr', a new vma is allocated
2429 * either for the first part or the tail.
2430 */
2431static int split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
2432 unsigned long addr, int new_below)
2433{
2434 if (vma->vm_mm->map_count >= sysctl_max_map_count)
2435 return -ENOMEM;
2436
2437 return __split_vma(vmi, vma, addr, new_below);
2438}
2439
2440/*
2441 * We are about to modify one or multiple of a VMA's flags, policy, userfaultfd
2442 * context and anonymous VMA name within the range [start, end).
2443 *
2444 * As a result, we might be able to merge the newly modified VMA range with an
2445 * adjacent VMA with identical properties.
2446 *
2447 * If no merge is possible and the range does not span the entirety of the VMA,
2448 * we then need to split the VMA to accommodate the change.
2449 *
2450 * The function returns either the merged VMA, the original VMA if a split was
2451 * required instead, or an error if the split failed.
2452 */
2453struct vm_area_struct *vma_modify(struct vma_iterator *vmi,
2454 struct vm_area_struct *prev,
2455 struct vm_area_struct *vma,
2456 unsigned long start, unsigned long end,
2457 unsigned long vm_flags,
2458 struct mempolicy *policy,
2459 struct vm_userfaultfd_ctx uffd_ctx,
2460 struct anon_vma_name *anon_name)
2461{
2462 pgoff_t pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
2463 struct vm_area_struct *merged;
2464
2465 merged = vma_merge(vmi, mm: vma->vm_mm, prev, addr: start, end, vm_flags,
2466 anon_vma: vma->anon_vma, file: vma->vm_file, pgoff, policy,
2467 vm_userfaultfd_ctx: uffd_ctx, anon_name);
2468 if (merged)
2469 return merged;
2470
2471 if (vma->vm_start < start) {
2472 int err = split_vma(vmi, vma, addr: start, new_below: 1);
2473
2474 if (err)
2475 return ERR_PTR(error: err);
2476 }
2477
2478 if (vma->vm_end > end) {
2479 int err = split_vma(vmi, vma, addr: end, new_below: 0);
2480
2481 if (err)
2482 return ERR_PTR(error: err);
2483 }
2484
2485 return vma;
2486}
2487
2488/*
2489 * Attempt to merge a newly mapped VMA with those adjacent to it. The caller
2490 * must ensure that [start, end) does not overlap any existing VMA.
2491 */
2492static struct vm_area_struct
2493*vma_merge_new_vma(struct vma_iterator *vmi, struct vm_area_struct *prev,
2494 struct vm_area_struct *vma, unsigned long start,
2495 unsigned long end, pgoff_t pgoff)
2496{
2497 return vma_merge(vmi, mm: vma->vm_mm, prev, addr: start, end, vm_flags: vma->vm_flags,
2498 anon_vma: vma->anon_vma, file: vma->vm_file, pgoff, vma_policy(vma),
2499 vm_userfaultfd_ctx: vma->vm_userfaultfd_ctx, anon_name: anon_vma_name(vma));
2500}
2501
2502/*
2503 * Expand vma by delta bytes, potentially merging with an immediately adjacent
2504 * VMA with identical properties.
2505 */
2506struct vm_area_struct *vma_merge_extend(struct vma_iterator *vmi,
2507 struct vm_area_struct *vma,
2508 unsigned long delta)
2509{
2510 pgoff_t pgoff = vma->vm_pgoff + vma_pages(vma);
2511
2512 /* vma is specified as prev, so case 1 or 2 will apply. */
2513 return vma_merge(vmi, mm: vma->vm_mm, prev: vma, addr: vma->vm_end, end: vma->vm_end + delta,
2514 vm_flags: vma->vm_flags, anon_vma: vma->anon_vma, file: vma->vm_file, pgoff,
2515 vma_policy(vma), vm_userfaultfd_ctx: vma->vm_userfaultfd_ctx,
2516 anon_name: anon_vma_name(vma));
2517}
2518
2519/*
2520 * do_vmi_align_munmap() - munmap the aligned region from @start to @end.
2521 * @vmi: The vma iterator
2522 * @vma: The starting vm_area_struct
2523 * @mm: The mm_struct
2524 * @start: The aligned start address to munmap.
2525 * @end: The aligned end address to munmap.
2526 * @uf: The userfaultfd list_head
2527 * @unlock: Set to true to drop the mmap_lock. unlocking only happens on
2528 * success.
2529 *
2530 * Return: 0 on success and drops the lock if so directed, error and leaves the
2531 * lock held otherwise.
2532 */
2533static int
2534do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
2535 struct mm_struct *mm, unsigned long start,
2536 unsigned long end, struct list_head *uf, bool unlock)
2537{
2538 struct vm_area_struct *prev, *next = NULL;
2539 struct maple_tree mt_detach;
2540 int count = 0;
2541 int error = -ENOMEM;
2542 unsigned long locked_vm = 0;
2543 MA_STATE(mas_detach, &mt_detach, 0, 0);
2544 mt_init_flags(mt: &mt_detach, flags: vmi->mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
2545 mt_on_stack(mt_detach);
2546
2547 /*
2548 * If we need to split any vma, do it now to save pain later.
2549 *
2550 * Note: mremap's move_vma VM_ACCOUNT handling assumes a partially
2551 * unmapped vm_area_struct will remain in use: so lower split_vma
2552 * places tmp vma above, and higher split_vma places tmp vma below.
2553 */
2554
2555 /* Does it split the first one? */
2556 if (start > vma->vm_start) {
2557
2558 /*
2559 * Make sure that map_count on return from munmap() will
2560 * not exceed its limit; but let map_count go just above
2561 * its limit temporarily, to help free resources as expected.
2562 */
2563 if (end < vma->vm_end && mm->map_count >= sysctl_max_map_count)
2564 goto map_count_exceeded;
2565
2566 error = __split_vma(vmi, vma, addr: start, new_below: 1);
2567 if (error)
2568 goto start_split_failed;
2569 }
2570
2571 /*
2572 * Detach a range of VMAs from the mm. Using next as a temp variable as
2573 * it is always overwritten.
2574 */
2575 next = vma;
2576 do {
2577 /* Does it split the end? */
2578 if (next->vm_end > end) {
2579 error = __split_vma(vmi, vma: next, addr: end, new_below: 0);
2580 if (error)
2581 goto end_split_failed;
2582 }
2583 vma_start_write(vma: next);
2584 mas_set(mas: &mas_detach, index: count);
2585 error = mas_store_gfp(mas: &mas_detach, entry: next, GFP_KERNEL);
2586 if (error)
2587 goto munmap_gather_failed;
2588 vma_mark_detached(vma: next, detached: true);
2589 if (next->vm_flags & VM_LOCKED)
2590 locked_vm += vma_pages(vma: next);
2591
2592 count++;
2593 if (unlikely(uf)) {
2594 /*
2595 * If userfaultfd_unmap_prep returns an error the vmas
2596 * will remain split, but userland will get a
2597 * highly unexpected error anyway. This is no
2598 * different than the case where the first of the two
2599 * __split_vma fails, but we don't undo the first
2600 * split, despite we could. This is unlikely enough
2601 * failure that it's not worth optimizing it for.
2602 */
2603 error = userfaultfd_unmap_prep(vma: next, start, end, uf);
2604
2605 if (error)
2606 goto userfaultfd_error;
2607 }
2608#ifdef CONFIG_DEBUG_VM_MAPLE_TREE
2609 BUG_ON(next->vm_start < start);
2610 BUG_ON(next->vm_start > end);
2611#endif
2612 } for_each_vma_range(*vmi, next, end);
2613
2614#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
2615 /* Make sure no VMAs are about to be lost. */
2616 {
2617 MA_STATE(test, &mt_detach, 0, 0);
2618 struct vm_area_struct *vma_mas, *vma_test;
2619 int test_count = 0;
2620
2621 vma_iter_set(vmi, addr: start);
2622 rcu_read_lock();
2623 vma_test = mas_find(mas: &test, max: count - 1);
2624 for_each_vma_range(*vmi, vma_mas, end) {
2625 BUG_ON(vma_mas != vma_test);
2626 test_count++;
2627 vma_test = mas_next(mas: &test, max: count - 1);
2628 }
2629 rcu_read_unlock();
2630 BUG_ON(count != test_count);
2631 }
2632#endif
2633
2634 while (vma_iter_addr(vmi) > start)
2635 vma_iter_prev_range(vmi);
2636
2637 error = vma_iter_clear_gfp(vmi, start, end, GFP_KERNEL);
2638 if (error)
2639 goto clear_tree_failed;
2640
2641 /* Point of no return */
2642 mm->locked_vm -= locked_vm;
2643 mm->map_count -= count;
2644 if (unlock)
2645 mmap_write_downgrade(mm);
2646
2647 prev = vma_iter_prev_range(vmi);
2648 next = vma_next(vmi);
2649 if (next)
2650 vma_iter_prev_range(vmi);
2651
2652 /*
2653 * We can free page tables without write-locking mmap_lock because VMAs
2654 * were isolated before we downgraded mmap_lock.
2655 */
2656 mas_set(mas: &mas_detach, index: 1);
2657 unmap_region(mm, mas: &mas_detach, vma, prev, next, start, end, tree_end: count,
2658 mm_wr_locked: !unlock);
2659 /* Statistics and freeing VMAs */
2660 mas_set(mas: &mas_detach, index: 0);
2661 remove_mt(mm, mas: &mas_detach);
2662 validate_mm(mm);
2663 if (unlock)
2664 mmap_read_unlock(mm);
2665
2666 __mt_destroy(mt: &mt_detach);
2667 return 0;
2668
2669clear_tree_failed:
2670userfaultfd_error:
2671munmap_gather_failed:
2672end_split_failed:
2673 mas_set(mas: &mas_detach, index: 0);
2674 mas_for_each(&mas_detach, next, end)
2675 vma_mark_detached(vma: next, detached: false);
2676
2677 __mt_destroy(mt: &mt_detach);
2678start_split_failed:
2679map_count_exceeded:
2680 validate_mm(mm);
2681 return error;
2682}
2683
2684/*
2685 * do_vmi_munmap() - munmap a given range.
2686 * @vmi: The vma iterator
2687 * @mm: The mm_struct
2688 * @start: The start address to munmap
2689 * @len: The length of the range to munmap
2690 * @uf: The userfaultfd list_head
2691 * @unlock: set to true if the user wants to drop the mmap_lock on success
2692 *
2693 * This function takes a @mas that is either pointing to the previous VMA or set
2694 * to MA_START and sets it up to remove the mapping(s). The @len will be
2695 * aligned and any arch_unmap work will be preformed.
2696 *
2697 * Return: 0 on success and drops the lock if so directed, error and leaves the
2698 * lock held otherwise.
2699 */
2700int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
2701 unsigned long start, size_t len, struct list_head *uf,
2702 bool unlock)
2703{
2704 unsigned long end;
2705 struct vm_area_struct *vma;
2706
2707 if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
2708 return -EINVAL;
2709
2710 end = start + PAGE_ALIGN(len);
2711 if (end == start)
2712 return -EINVAL;
2713
2714 /* arch_unmap() might do unmaps itself. */
2715 arch_unmap(mm, start, end);
2716
2717 /* Find the first overlapping VMA */
2718 vma = vma_find(vmi, max: end);
2719 if (!vma) {
2720 if (unlock)
2721 mmap_write_unlock(mm);
2722 return 0;
2723 }
2724
2725 return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
2726}
2727
2728/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
2729 * @mm: The mm_struct
2730 * @start: The start address to munmap
2731 * @len: The length to be munmapped.
2732 * @uf: The userfaultfd list_head
2733 *
2734 * Return: 0 on success, error otherwise.
2735 */
2736int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
2737 struct list_head *uf)
2738{
2739 VMA_ITERATOR(vmi, mm, start);
2740
2741 return do_vmi_munmap(vmi: &vmi, mm, start, len, uf, unlock: false);
2742}
2743
2744unsigned long mmap_region(struct file *file, unsigned long addr,
2745 unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
2746 struct list_head *uf)
2747{
2748 struct mm_struct *mm = current->mm;
2749 struct vm_area_struct *vma = NULL;
2750 struct vm_area_struct *next, *prev, *merge;
2751 pgoff_t pglen = len >> PAGE_SHIFT;
2752 unsigned long charged = 0;
2753 unsigned long end = addr + len;
2754 unsigned long merge_start = addr, merge_end = end;
2755 bool writable_file_mapping = false;
2756 pgoff_t vm_pgoff;
2757 int error;
2758 VMA_ITERATOR(vmi, mm, addr);
2759
2760 /* Check against address space limit. */
2761 if (!may_expand_vm(mm, vm_flags, npages: len >> PAGE_SHIFT)) {
2762 unsigned long nr_pages;
2763
2764 /*
2765 * MAP_FIXED may remove pages of mappings that intersects with
2766 * requested mapping. Account for the pages it would unmap.
2767 */
2768 nr_pages = count_vma_pages_range(mm, addr, end);
2769
2770 if (!may_expand_vm(mm, vm_flags,
2771 npages: (len >> PAGE_SHIFT) - nr_pages))
2772 return -ENOMEM;
2773 }
2774
2775 /* Unmap any existing mapping in the area */
2776 if (do_vmi_munmap(vmi: &vmi, mm, start: addr, len, uf, unlock: false))
2777 return -ENOMEM;
2778
2779 /*
2780 * Private writable mapping: check memory availability
2781 */
2782 if (accountable_mapping(file, vm_flags)) {
2783 charged = len >> PAGE_SHIFT;
2784 if (security_vm_enough_memory_mm(mm, pages: charged))
2785 return -ENOMEM;
2786 vm_flags |= VM_ACCOUNT;
2787 }
2788
2789 next = vma_next(vmi: &vmi);
2790 prev = vma_prev(vmi: &vmi);
2791 if (vm_flags & VM_SPECIAL) {
2792 if (prev)
2793 vma_iter_next_range(vmi: &vmi);
2794 goto cannot_expand;
2795 }
2796
2797 /* Attempt to expand an old mapping */
2798 /* Check next */
2799 if (next && next->vm_start == end && !vma_policy(next) &&
2800 can_vma_merge_before(vma: next, vm_flags, NULL, file, vm_pgoff: pgoff+pglen,
2801 NULL_VM_UFFD_CTX, NULL)) {
2802 merge_end = next->vm_end;
2803 vma = next;
2804 vm_pgoff = next->vm_pgoff - pglen;
2805 }
2806
2807 /* Check prev */
2808 if (prev && prev->vm_end == addr && !vma_policy(prev) &&
2809 (vma ? can_vma_merge_after(vma: prev, vm_flags, anon_vma: vma->anon_vma, file,
2810 vm_pgoff: pgoff, vm_userfaultfd_ctx: vma->vm_userfaultfd_ctx, NULL) :
2811 can_vma_merge_after(vma: prev, vm_flags, NULL, file, vm_pgoff: pgoff,
2812 NULL_VM_UFFD_CTX, NULL))) {
2813 merge_start = prev->vm_start;
2814 vma = prev;
2815 vm_pgoff = prev->vm_pgoff;
2816 } else if (prev) {
2817 vma_iter_next_range(vmi: &vmi);
2818 }
2819
2820 /* Actually expand, if possible */
2821 if (vma &&
2822 !vma_expand(vmi: &vmi, vma, start: merge_start, end: merge_end, pgoff: vm_pgoff, next)) {
2823 khugepaged_enter_vma(vma, vm_flags);
2824 goto expanded;
2825 }
2826
2827 if (vma == prev)
2828 vma_iter_set(vmi: &vmi, addr);
2829cannot_expand:
2830
2831 /*
2832 * Determine the object being mapped and call the appropriate
2833 * specific mapper. the address has already been validated, but
2834 * not unmapped, but the maps are removed from the list.
2835 */
2836 vma = vm_area_alloc(mm);
2837 if (!vma) {
2838 error = -ENOMEM;
2839 goto unacct_error;
2840 }
2841
2842 vma_iter_config(vmi: &vmi, index: addr, last: end);
2843 vma->vm_start = addr;
2844 vma->vm_end = end;
2845 vm_flags_init(vma, flags: vm_flags);
2846 vma->vm_page_prot = vm_get_page_prot(vm_flags);
2847 vma->vm_pgoff = pgoff;
2848
2849 if (file) {
2850 vma->vm_file = get_file(f: file);
2851 error = call_mmap(file, vma);
2852 if (error)
2853 goto unmap_and_free_vma;
2854
2855 if (vma_is_shared_maywrite(vma)) {
2856 error = mapping_map_writable(mapping: file->f_mapping);
2857 if (error)
2858 goto close_and_free_vma;
2859
2860 writable_file_mapping = true;
2861 }
2862
2863 /*
2864 * Expansion is handled above, merging is handled below.
2865 * Drivers should not alter the address of the VMA.
2866 */
2867 error = -EINVAL;
2868 if (WARN_ON((addr != vma->vm_start)))
2869 goto close_and_free_vma;
2870
2871 vma_iter_config(vmi: &vmi, index: addr, last: end);
2872 /*
2873 * If vm_flags changed after call_mmap(), we should try merge
2874 * vma again as we may succeed this time.
2875 */
2876 if (unlikely(vm_flags != vma->vm_flags && prev)) {
2877 merge = vma_merge_new_vma(vmi: &vmi, prev, vma,
2878 start: vma->vm_start, end: vma->vm_end,
2879 pgoff: vma->vm_pgoff);
2880 if (merge) {
2881 /*
2882 * ->mmap() can change vma->vm_file and fput
2883 * the original file. So fput the vma->vm_file
2884 * here or we would add an extra fput for file
2885 * and cause general protection fault
2886 * ultimately.
2887 */
2888 fput(vma->vm_file);
2889 vm_area_free(vma);
2890 vma = merge;
2891 /* Update vm_flags to pick up the change. */
2892 vm_flags = vma->vm_flags;
2893 goto unmap_writable;
2894 }
2895 }
2896
2897 vm_flags = vma->vm_flags;
2898 } else if (vm_flags & VM_SHARED) {
2899 error = shmem_zero_setup(vma);
2900 if (error)
2901 goto free_vma;
2902 } else {
2903 vma_set_anonymous(vma);
2904 }
2905
2906 if (map_deny_write_exec(vma, vm_flags: vma->vm_flags)) {
2907 error = -EACCES;
2908 goto close_and_free_vma;
2909 }
2910
2911 /* Allow architectures to sanity-check the vm_flags */
2912 error = -EINVAL;
2913 if (!arch_validate_flags(flags: vma->vm_flags))
2914 goto close_and_free_vma;
2915
2916 error = -ENOMEM;
2917 if (vma_iter_prealloc(vmi: &vmi, vma))
2918 goto close_and_free_vma;
2919
2920 /* Lock the VMA since it is modified after insertion into VMA tree */
2921 vma_start_write(vma);
2922 vma_iter_store(vmi: &vmi, vma);
2923 mm->map_count++;
2924 if (vma->vm_file) {
2925 i_mmap_lock_write(mapping: vma->vm_file->f_mapping);
2926 if (vma_is_shared_maywrite(vma))
2927 mapping_allow_writable(mapping: vma->vm_file->f_mapping);
2928
2929 flush_dcache_mmap_lock(mapping: vma->vm_file->f_mapping);
2930 vma_interval_tree_insert(node: vma, root: &vma->vm_file->f_mapping->i_mmap);
2931 flush_dcache_mmap_unlock(mapping: vma->vm_file->f_mapping);
2932 i_mmap_unlock_write(mapping: vma->vm_file->f_mapping);
2933 }
2934
2935 /*
2936 * vma_merge() calls khugepaged_enter_vma() either, the below
2937 * call covers the non-merge case.
2938 */
2939 khugepaged_enter_vma(vma, vm_flags: vma->vm_flags);
2940
2941 /* Once vma denies write, undo our temporary denial count */
2942unmap_writable:
2943 if (writable_file_mapping)
2944 mapping_unmap_writable(mapping: file->f_mapping);
2945 file = vma->vm_file;
2946 ksm_add_vma(vma);
2947expanded:
2948 perf_event_mmap(vma);
2949
2950 vm_stat_account(mm, vm_flags, npages: len >> PAGE_SHIFT);
2951 if (vm_flags & VM_LOCKED) {
2952 if ((vm_flags & VM_SPECIAL) || vma_is_dax(vma) ||
2953 is_vm_hugetlb_page(vma) ||
2954 vma == get_gate_vma(current->mm))
2955 vm_flags_clear(vma, VM_LOCKED_MASK);
2956 else
2957 mm->locked_vm += (len >> PAGE_SHIFT);
2958 }
2959
2960 if (file)
2961 uprobe_mmap(vma);
2962
2963 /*
2964 * New (or expanded) vma always get soft dirty status.
2965 * Otherwise user-space soft-dirty page tracker won't
2966 * be able to distinguish situation when vma area unmapped,
2967 * then new mapped in-place (which must be aimed as
2968 * a completely new data area).
2969 */
2970 vm_flags_set(vma, VM_SOFTDIRTY);
2971
2972 vma_set_page_prot(vma);
2973
2974 validate_mm(mm);
2975 return addr;
2976
2977close_and_free_vma:
2978 if (file && vma->vm_ops && vma->vm_ops->close)
2979 vma->vm_ops->close(vma);
2980
2981 if (file || vma->vm_file) {
2982unmap_and_free_vma:
2983 fput(vma->vm_file);
2984 vma->vm_file = NULL;
2985
2986 vma_iter_set(vmi: &vmi, addr: vma->vm_end);
2987 /* Undo any partial mapping done by a device driver. */
2988 unmap_region(mm, mas: &vmi.mas, vma, prev, next, start: vma->vm_start,
2989 end: vma->vm_end, tree_end: vma->vm_end, mm_wr_locked: true);
2990 }
2991 if (writable_file_mapping)
2992 mapping_unmap_writable(mapping: file->f_mapping);
2993free_vma:
2994 vm_area_free(vma);
2995unacct_error:
2996 if (charged)
2997 vm_unacct_memory(pages: charged);
2998 validate_mm(mm);
2999 return error;
3000}
3001
3002static int __vm_munmap(unsigned long start, size_t len, bool unlock)
3003{
3004 int ret;
3005 struct mm_struct *mm = current->mm;
3006 LIST_HEAD(uf);
3007 VMA_ITERATOR(vmi, mm, start);
3008
3009 if (mmap_write_lock_killable(mm))
3010 return -EINTR;
3011
3012 ret = do_vmi_munmap(vmi: &vmi, mm, start, len, uf: &uf, unlock);
3013 if (ret || !unlock)
3014 mmap_write_unlock(mm);
3015
3016 userfaultfd_unmap_complete(mm, uf: &uf);
3017 return ret;
3018}
3019
3020int vm_munmap(unsigned long start, size_t len)
3021{
3022 return __vm_munmap(start, len, unlock: false);
3023}
3024EXPORT_SYMBOL(vm_munmap);
3025
3026SYSCALL_DEFINE2(munmap, unsigned long, addr, size_t, len)
3027{
3028 addr = untagged_addr(addr);
3029 return __vm_munmap(start: addr, len, unlock: true);
3030}
3031
3032
3033/*
3034 * Emulation of deprecated remap_file_pages() syscall.
3035 */
3036SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
3037 unsigned long, prot, unsigned long, pgoff, unsigned long, flags)
3038{
3039
3040 struct mm_struct *mm = current->mm;
3041 struct vm_area_struct *vma;
3042 unsigned long populate = 0;
3043 unsigned long ret = -EINVAL;
3044 struct file *file;
3045
3046 pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/mm/remap_file_pages.rst.\n",
3047 current->comm, current->pid);
3048
3049 if (prot)
3050 return ret;
3051 start = start & PAGE_MASK;
3052 size = size & PAGE_MASK;
3053
3054 if (start + size <= start)
3055 return ret;
3056
3057 /* Does pgoff wrap? */
3058 if (pgoff + (size >> PAGE_SHIFT) < pgoff)
3059 return ret;
3060
3061 if (mmap_write_lock_killable(mm))
3062 return -EINTR;
3063
3064 vma = vma_lookup(mm, addr: start);
3065
3066 if (!vma || !(vma->vm_flags & VM_SHARED))
3067 goto out;
3068
3069 if (start + size > vma->vm_end) {
3070 VMA_ITERATOR(vmi, mm, vma->vm_end);
3071 struct vm_area_struct *next, *prev = vma;
3072
3073 for_each_vma_range(vmi, next, start + size) {
3074 /* hole between vmas ? */
3075 if (next->vm_start != prev->vm_end)
3076 goto out;
3077
3078 if (next->vm_file != vma->vm_file)
3079 goto out;
3080
3081 if (next->vm_flags != vma->vm_flags)
3082 goto out;
3083
3084 if (start + size <= next->vm_end)
3085 break;
3086
3087 prev = next;
3088 }
3089
3090 if (!next)
3091 goto out;
3092 }
3093
3094 prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
3095 prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
3096 prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
3097
3098 flags &= MAP_NONBLOCK;
3099 flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
3100 if (vma->vm_flags & VM_LOCKED)
3101 flags |= MAP_LOCKED;
3102
3103 file = get_file(f: vma->vm_file);
3104 ret = do_mmap(file: vma->vm_file, addr: start, len: size,
3105 prot, flags, vm_flags: 0, pgoff, populate: &populate, NULL);
3106 fput(file);
3107out:
3108 mmap_write_unlock(mm);
3109 if (populate)
3110 mm_populate(addr: ret, len: populate);
3111 if (!IS_ERR_VALUE(ret))
3112 ret = 0;
3113 return ret;
3114}
3115
3116/*
3117 * do_vma_munmap() - Unmap a full or partial vma.
3118 * @vmi: The vma iterator pointing at the vma
3119 * @vma: The first vma to be munmapped
3120 * @start: the start of the address to unmap
3121 * @end: The end of the address to unmap
3122 * @uf: The userfaultfd list_head
3123 * @unlock: Drop the lock on success
3124 *
3125 * unmaps a VMA mapping when the vma iterator is already in position.
3126 * Does not handle alignment.
3127 *
3128 * Return: 0 on success drops the lock of so directed, error on failure and will
3129 * still hold the lock.
3130 */
3131int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
3132 unsigned long start, unsigned long end, struct list_head *uf,
3133 bool unlock)
3134{
3135 struct mm_struct *mm = vma->vm_mm;
3136
3137 arch_unmap(mm, start, end);
3138 return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
3139}
3140
3141/*
3142 * do_brk_flags() - Increase the brk vma if the flags match.
3143 * @vmi: The vma iterator
3144 * @addr: The start address
3145 * @len: The length of the increase
3146 * @vma: The vma,
3147 * @flags: The VMA Flags
3148 *
3149 * Extend the brk VMA from addr to addr + len. If the VMA is NULL or the flags
3150 * do not match then create a new anonymous VMA. Eventually we may be able to
3151 * do some brk-specific accounting here.
3152 */
3153static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
3154 unsigned long addr, unsigned long len, unsigned long flags)
3155{
3156 struct mm_struct *mm = current->mm;
3157 struct vma_prepare vp;
3158
3159 /*
3160 * Check against address space limits by the changed size
3161 * Note: This happens *after* clearing old mappings in some code paths.
3162 */
3163 flags |= VM_DATA_DEFAULT_FLAGS | VM_ACCOUNT | mm->def_flags;
3164 if (!may_expand_vm(mm, flags, npages: len >> PAGE_SHIFT))
3165 return -ENOMEM;
3166
3167 if (mm->map_count > sysctl_max_map_count)
3168 return -ENOMEM;
3169
3170 if (security_vm_enough_memory_mm(mm, pages: len >> PAGE_SHIFT))
3171 return -ENOMEM;
3172
3173 /*
3174 * Expand the existing vma if possible; Note that singular lists do not
3175 * occur after forking, so the expand will only happen on new VMAs.
3176 */
3177 if (vma && vma->vm_end == addr && !vma_policy(vma) &&
3178 can_vma_merge_after(vma, vm_flags: flags, NULL, NULL,
3179 vm_pgoff: addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
3180 vma_iter_config(vmi, index: vma->vm_start, last: addr + len);
3181 if (vma_iter_prealloc(vmi, vma))
3182 goto unacct_fail;
3183
3184 vma_start_write(vma);
3185
3186 init_vma_prep(vp: &vp, vma);
3187 vma_prepare(vp: &vp);
3188 vma_adjust_trans_huge(vma, start: vma->vm_start, end: addr + len, adjust_next: 0);
3189 vma->vm_end = addr + len;
3190 vm_flags_set(vma, VM_SOFTDIRTY);
3191 vma_iter_store(vmi, vma);
3192
3193 vma_complete(vp: &vp, vmi, mm);
3194 khugepaged_enter_vma(vma, vm_flags: flags);
3195 goto out;
3196 }
3197
3198 if (vma)
3199 vma_iter_next_range(vmi);
3200 /* create a vma struct for an anonymous mapping */
3201 vma = vm_area_alloc(mm);
3202 if (!vma)
3203 goto unacct_fail;
3204
3205 vma_set_anonymous(vma);
3206 vma->vm_start = addr;
3207 vma->vm_end = addr + len;
3208 vma->vm_pgoff = addr >> PAGE_SHIFT;
3209 vm_flags_init(vma, flags);
3210 vma->vm_page_prot = vm_get_page_prot(vm_flags: flags);
3211 vma_start_write(vma);
3212 if (vma_iter_store_gfp(vmi, vma, GFP_KERNEL))
3213 goto mas_store_fail;
3214
3215 mm->map_count++;
3216 validate_mm(mm);
3217 ksm_add_vma(vma);
3218out:
3219 perf_event_mmap(vma);
3220 mm->total_vm += len >> PAGE_SHIFT;
3221 mm->data_vm += len >> PAGE_SHIFT;
3222 if (flags & VM_LOCKED)
3223 mm->locked_vm += (len >> PAGE_SHIFT);
3224 vm_flags_set(vma, VM_SOFTDIRTY);
3225 return 0;
3226
3227mas_store_fail:
3228 vm_area_free(vma);
3229unacct_fail:
3230 vm_unacct_memory(pages: len >> PAGE_SHIFT);
3231 return -ENOMEM;
3232}
3233
3234int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
3235{
3236 struct mm_struct *mm = current->mm;
3237 struct vm_area_struct *vma = NULL;
3238 unsigned long len;
3239 int ret;
3240 bool populate;
3241 LIST_HEAD(uf);
3242 VMA_ITERATOR(vmi, mm, addr);
3243
3244 len = PAGE_ALIGN(request);
3245 if (len < request)
3246 return -ENOMEM;
3247 if (!len)
3248 return 0;
3249
3250 /* Until we need other flags, refuse anything except VM_EXEC. */
3251 if ((flags & (~VM_EXEC)) != 0)
3252 return -EINVAL;
3253
3254 if (mmap_write_lock_killable(mm))
3255 return -EINTR;
3256
3257 ret = check_brk_limits(addr, len);
3258 if (ret)
3259 goto limits_failed;
3260
3261 ret = do_vmi_munmap(vmi: &vmi, mm, start: addr, len, uf: &uf, unlock: 0);
3262 if (ret)
3263 goto munmap_failed;
3264
3265 vma = vma_prev(vmi: &vmi);
3266 ret = do_brk_flags(vmi: &vmi, vma, addr, len, flags);
3267 populate = ((mm->def_flags & VM_LOCKED) != 0);
3268 mmap_write_unlock(mm);
3269 userfaultfd_unmap_complete(mm, uf: &uf);
3270 if (populate && !ret)
3271 mm_populate(addr, len);
3272 return ret;
3273
3274munmap_failed:
3275limits_failed:
3276 mmap_write_unlock(mm);
3277 return ret;
3278}
3279EXPORT_SYMBOL(vm_brk_flags);
3280
3281/* Release all mmaps. */
3282void exit_mmap(struct mm_struct *mm)
3283{
3284 struct mmu_gather tlb;
3285 struct vm_area_struct *vma;
3286 unsigned long nr_accounted = 0;
3287 MA_STATE(mas, &mm->mm_mt, 0, 0);
3288 int count = 0;
3289
3290 /* mm's last user has gone, and its about to be pulled down */
3291 mmu_notifier_release(mm);
3292
3293 mmap_read_lock(mm);
3294 arch_exit_mmap(mm);
3295
3296 vma = mas_find(mas: &mas, ULONG_MAX);
3297 if (!vma) {
3298 /* Can happen if dup_mmap() received an OOM */
3299 mmap_read_unlock(mm);
3300 return;
3301 }
3302
3303 lru_add_drain();
3304 flush_cache_mm(mm);
3305 tlb_gather_mmu_fullmm(tlb: &tlb, mm);
3306 /* update_hiwater_rss(mm) here? but nobody should be looking */
3307 /* Use ULONG_MAX here to ensure all VMAs in the mm are unmapped */
3308 unmap_vmas(tlb: &tlb, mas: &mas, start_vma: vma, start: 0, ULONG_MAX, ULONG_MAX, mm_wr_locked: false);
3309 mmap_read_unlock(mm);
3310
3311 /*
3312 * Set MMF_OOM_SKIP to hide this task from the oom killer/reaper
3313 * because the memory has been already freed.
3314 */
3315 set_bit(MMF_OOM_SKIP, addr: &mm->flags);
3316 mmap_write_lock(mm);
3317 mt_clear_in_rcu(mt: &mm->mm_mt);
3318 mas_set(mas: &mas, index: vma->vm_end);
3319 free_pgtables(tlb: &tlb, mas: &mas, start_vma: vma, FIRST_USER_ADDRESS,
3320 USER_PGTABLES_CEILING, mm_wr_locked: true);
3321 tlb_finish_mmu(tlb: &tlb);
3322
3323 /*
3324 * Walk the list again, actually closing and freeing it, with preemption
3325 * enabled, without holding any MM locks besides the unreachable
3326 * mmap_write_lock.
3327 */
3328 mas_set(mas: &mas, index: vma->vm_end);
3329 do {
3330 if (vma->vm_flags & VM_ACCOUNT)
3331 nr_accounted += vma_pages(vma);
3332 remove_vma(vma, unreachable: true);
3333 count++;
3334 cond_resched();
3335 } while ((vma = mas_find(mas: &mas, ULONG_MAX)) != NULL);
3336
3337 BUG_ON(count != mm->map_count);
3338
3339 trace_exit_mmap(mm);
3340 __mt_destroy(mt: &mm->mm_mt);
3341 mmap_write_unlock(mm);
3342 vm_unacct_memory(pages: nr_accounted);
3343}
3344
3345/* Insert vm structure into process list sorted by address
3346 * and into the inode's i_mmap tree. If vm_file is non-NULL
3347 * then i_mmap_rwsem is taken here.
3348 */
3349int insert_vm_struct(struct mm_struct *mm, struct vm_area_struct *vma)
3350{
3351 unsigned long charged = vma_pages(vma);
3352
3353
3354 if (find_vma_intersection(mm, vma->vm_start, vma->vm_end))
3355 return -ENOMEM;
3356
3357 if ((vma->vm_flags & VM_ACCOUNT) &&
3358 security_vm_enough_memory_mm(mm, pages: charged))
3359 return -ENOMEM;
3360
3361 /*
3362 * The vm_pgoff of a purely anonymous vma should be irrelevant
3363 * until its first write fault, when page's anon_vma and index
3364 * are set. But now set the vm_pgoff it will almost certainly
3365 * end up with (unless mremap moves it elsewhere before that
3366 * first wfault), so /proc/pid/maps tells a consistent story.
3367 *
3368 * By setting it to reflect the virtual start address of the
3369 * vma, merges and splits can happen in a seamless way, just
3370 * using the existing file pgoff checks and manipulations.
3371 * Similarly in do_mmap and in do_brk_flags.
3372 */
3373 if (vma_is_anonymous(vma)) {
3374 BUG_ON(vma->anon_vma);
3375 vma->vm_pgoff = vma->vm_start >> PAGE_SHIFT;
3376 }
3377
3378 if (vma_link(mm, vma)) {
3379 if (vma->vm_flags & VM_ACCOUNT)
3380 vm_unacct_memory(pages: charged);
3381 return -ENOMEM;
3382 }
3383
3384 return 0;
3385}
3386
3387/*
3388 * Copy the vma structure to a new location in the same mm,
3389 * prior to moving page table entries, to effect an mremap move.
3390 */
3391struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
3392 unsigned long addr, unsigned long len, pgoff_t pgoff,
3393 bool *need_rmap_locks)
3394{
3395 struct vm_area_struct *vma = *vmap;
3396 unsigned long vma_start = vma->vm_start;
3397 struct mm_struct *mm = vma->vm_mm;
3398 struct vm_area_struct *new_vma, *prev;
3399 bool faulted_in_anon_vma = true;
3400 VMA_ITERATOR(vmi, mm, addr);
3401
3402 /*
3403 * If anonymous vma has not yet been faulted, update new pgoff
3404 * to match new location, to increase its chance of merging.
3405 */
3406 if (unlikely(vma_is_anonymous(vma) && !vma->anon_vma)) {
3407 pgoff = addr >> PAGE_SHIFT;
3408 faulted_in_anon_vma = false;
3409 }
3410
3411 new_vma = find_vma_prev(mm, addr, pprev: &prev);
3412 if (new_vma && new_vma->vm_start < addr + len)
3413 return NULL; /* should never get here */
3414
3415 new_vma = vma_merge_new_vma(vmi: &vmi, prev, vma, start: addr, end: addr + len, pgoff);
3416 if (new_vma) {
3417 /*
3418 * Source vma may have been merged into new_vma
3419 */
3420 if (unlikely(vma_start >= new_vma->vm_start &&
3421 vma_start < new_vma->vm_end)) {
3422 /*
3423 * The only way we can get a vma_merge with
3424 * self during an mremap is if the vma hasn't
3425 * been faulted in yet and we were allowed to
3426 * reset the dst vma->vm_pgoff to the
3427 * destination address of the mremap to allow
3428 * the merge to happen. mremap must change the
3429 * vm_pgoff linearity between src and dst vmas
3430 * (in turn preventing a vma_merge) to be
3431 * safe. It is only safe to keep the vm_pgoff
3432 * linear if there are no pages mapped yet.
3433 */
3434 VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
3435 *vmap = vma = new_vma;
3436 }
3437 *need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
3438 } else {
3439 new_vma = vm_area_dup(vma);
3440 if (!new_vma)
3441 goto out;
3442 new_vma->vm_start = addr;
3443 new_vma->vm_end = addr + len;
3444 new_vma->vm_pgoff = pgoff;
3445 if (vma_dup_policy(src: vma, dst: new_vma))
3446 goto out_free_vma;
3447 if (anon_vma_clone(new_vma, vma))
3448 goto out_free_mempol;
3449 if (new_vma->vm_file)
3450 get_file(f: new_vma->vm_file);
3451 if (new_vma->vm_ops && new_vma->vm_ops->open)
3452 new_vma->vm_ops->open(new_vma);
3453 if (vma_link(mm, vma: new_vma))
3454 goto out_vma_link;
3455 *need_rmap_locks = false;
3456 }
3457 return new_vma;
3458
3459out_vma_link:
3460 if (new_vma->vm_ops && new_vma->vm_ops->close)
3461 new_vma->vm_ops->close(new_vma);
3462
3463 if (new_vma->vm_file)
3464 fput(new_vma->vm_file);
3465
3466 unlink_anon_vmas(new_vma);
3467out_free_mempol:
3468 mpol_put(vma_policy(new_vma));
3469out_free_vma:
3470 vm_area_free(new_vma);
3471out:
3472 return NULL;
3473}
3474
3475/*
3476 * Return true if the calling process may expand its vm space by the passed
3477 * number of pages
3478 */
3479bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
3480{
3481 if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT)
3482 return false;
3483
3484 if (is_data_mapping(flags) &&
3485 mm->data_vm + npages > rlimit(RLIMIT_DATA) >> PAGE_SHIFT) {
3486 /* Workaround for Valgrind */
3487 if (rlimit(RLIMIT_DATA) == 0 &&
3488 mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
3489 return true;
3490
3491 pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
3492 current->comm, current->pid,
3493 (mm->data_vm + npages) << PAGE_SHIFT,
3494 rlimit(RLIMIT_DATA),
3495 ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
3496
3497 if (!ignore_rlimit_data)
3498 return false;
3499 }
3500
3501 return true;
3502}
3503
3504void vm_stat_account(struct mm_struct *mm, vm_flags_t flags, long npages)
3505{
3506 WRITE_ONCE(mm->total_vm, READ_ONCE(mm->total_vm)+npages);
3507
3508 if (is_exec_mapping(flags))
3509 mm->exec_vm += npages;
3510 else if (is_stack_mapping(flags))
3511 mm->stack_vm += npages;
3512 else if (is_data_mapping(flags))
3513 mm->data_vm += npages;
3514}
3515
3516static vm_fault_t special_mapping_fault(struct vm_fault *vmf);
3517
3518/*
3519 * Having a close hook prevents vma merging regardless of flags.
3520 */
3521static void special_mapping_close(struct vm_area_struct *vma)
3522{
3523}
3524
3525static const char *special_mapping_name(struct vm_area_struct *vma)
3526{
3527 return ((struct vm_special_mapping *)vma->vm_private_data)->name;
3528}
3529
3530static int special_mapping_mremap(struct vm_area_struct *new_vma)
3531{
3532 struct vm_special_mapping *sm = new_vma->vm_private_data;
3533
3534 if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
3535 return -EFAULT;
3536
3537 if (sm->mremap)
3538 return sm->mremap(sm, new_vma);
3539
3540 return 0;
3541}
3542
3543static int special_mapping_split(struct vm_area_struct *vma, unsigned long addr)
3544{
3545 /*
3546 * Forbid splitting special mappings - kernel has expectations over
3547 * the number of pages in mapping. Together with VM_DONTEXPAND
3548 * the size of vma should stay the same over the special mapping's
3549 * lifetime.
3550 */
3551 return -EINVAL;
3552}
3553
3554static const struct vm_operations_struct special_mapping_vmops = {
3555 .close = special_mapping_close,
3556 .fault = special_mapping_fault,
3557 .mremap = special_mapping_mremap,
3558 .name = special_mapping_name,
3559 /* vDSO code relies that VVAR can't be accessed remotely */
3560 .access = NULL,
3561 .may_split = special_mapping_split,
3562};
3563
3564static const struct vm_operations_struct legacy_special_mapping_vmops = {
3565 .close = special_mapping_close,
3566 .fault = special_mapping_fault,
3567};
3568
3569static vm_fault_t special_mapping_fault(struct vm_fault *vmf)
3570{
3571 struct vm_area_struct *vma = vmf->vma;
3572 pgoff_t pgoff;
3573 struct page **pages;
3574
3575 if (vma->vm_ops == &legacy_special_mapping_vmops) {
3576 pages = vma->vm_private_data;
3577 } else {
3578 struct vm_special_mapping *sm = vma->vm_private_data;
3579
3580 if (sm->fault)
3581 return sm->fault(sm, vmf->vma, vmf);
3582
3583 pages = sm->pages;
3584 }
3585
3586 for (pgoff = vmf->pgoff; pgoff && *pages; ++pages)
3587 pgoff--;
3588
3589 if (*pages) {
3590 struct page *page = *pages;
3591 get_page(page);
3592 vmf->page = page;
3593 return 0;
3594 }
3595
3596 return VM_FAULT_SIGBUS;
3597}
3598
3599static struct vm_area_struct *__install_special_mapping(
3600 struct mm_struct *mm,
3601 unsigned long addr, unsigned long len,
3602 unsigned long vm_flags, void *priv,
3603 const struct vm_operations_struct *ops)
3604{
3605 int ret;
3606 struct vm_area_struct *vma;
3607
3608 vma = vm_area_alloc(mm);
3609 if (unlikely(vma == NULL))
3610 return ERR_PTR(error: -ENOMEM);
3611
3612 vma->vm_start = addr;
3613 vma->vm_end = addr + len;
3614
3615 vm_flags_init(vma, flags: (vm_flags | mm->def_flags |
3616 VM_DONTEXPAND | VM_SOFTDIRTY) & ~VM_LOCKED_MASK);
3617 vma->vm_page_prot = vm_get_page_prot(vm_flags: vma->vm_flags);
3618
3619 vma->vm_ops = ops;
3620 vma->vm_private_data = priv;
3621
3622 ret = insert_vm_struct(mm, vma);
3623 if (ret)
3624 goto out;
3625
3626 vm_stat_account(mm, flags: vma->vm_flags, npages: len >> PAGE_SHIFT);
3627
3628 perf_event_mmap(vma);
3629
3630 return vma;
3631
3632out:
3633 vm_area_free(vma);
3634 return ERR_PTR(error: ret);
3635}
3636
3637bool vma_is_special_mapping(const struct vm_area_struct *vma,
3638 const struct vm_special_mapping *sm)
3639{
3640 return vma->vm_private_data == sm &&
3641 (vma->vm_ops == &special_mapping_vmops ||
3642 vma->vm_ops == &legacy_special_mapping_vmops);
3643}
3644
3645/*
3646 * Called with mm->mmap_lock held for writing.
3647 * Insert a new vma covering the given region, with the given flags.
3648 * Its pages are supplied by the given array of struct page *.
3649 * The array can be shorter than len >> PAGE_SHIFT if it's null-terminated.
3650 * The region past the last page supplied will always produce SIGBUS.
3651 * The array pointer and the pages it points to are assumed to stay alive
3652 * for as long as this mapping might exist.
3653 */
3654struct vm_area_struct *_install_special_mapping(
3655 struct mm_struct *mm,
3656 unsigned long addr, unsigned long len,
3657 unsigned long vm_flags, const struct vm_special_mapping *spec)
3658{
3659 return __install_special_mapping(mm, addr, len, vm_flags, priv: (void *)spec,
3660 ops: &special_mapping_vmops);
3661}
3662
3663int install_special_mapping(struct mm_struct *mm,
3664 unsigned long addr, unsigned long len,
3665 unsigned long vm_flags, struct page **pages)
3666{
3667 struct vm_area_struct *vma = __install_special_mapping(
3668 mm, addr, len, vm_flags, priv: (void *)pages,
3669 ops: &legacy_special_mapping_vmops);
3670
3671 return PTR_ERR_OR_ZERO(ptr: vma);
3672}
3673
3674static DEFINE_MUTEX(mm_all_locks_mutex);
3675
3676static void vm_lock_anon_vma(struct mm_struct *mm, struct anon_vma *anon_vma)
3677{
3678 if (!test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3679 /*
3680 * The LSB of head.next can't change from under us
3681 * because we hold the mm_all_locks_mutex.
3682 */
3683 down_write_nest_lock(&anon_vma->root->rwsem, &mm->mmap_lock);
3684 /*
3685 * We can safely modify head.next after taking the
3686 * anon_vma->root->rwsem. If some other vma in this mm shares
3687 * the same anon_vma we won't take it again.
3688 *
3689 * No need of atomic instructions here, head.next
3690 * can't change from under us thanks to the
3691 * anon_vma->root->rwsem.
3692 */
3693 if (__test_and_set_bit(0, (unsigned long *)
3694 &anon_vma->root->rb_root.rb_root.rb_node))
3695 BUG();
3696 }
3697}
3698
3699static void vm_lock_mapping(struct mm_struct *mm, struct address_space *mapping)
3700{
3701 if (!test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3702 /*
3703 * AS_MM_ALL_LOCKS can't change from under us because
3704 * we hold the mm_all_locks_mutex.
3705 *
3706 * Operations on ->flags have to be atomic because
3707 * even if AS_MM_ALL_LOCKS is stable thanks to the
3708 * mm_all_locks_mutex, there may be other cpus
3709 * changing other bitflags in parallel to us.
3710 */
3711 if (test_and_set_bit(nr: AS_MM_ALL_LOCKS, addr: &mapping->flags))
3712 BUG();
3713 down_write_nest_lock(&mapping->i_mmap_rwsem, &mm->mmap_lock);
3714 }
3715}
3716
3717/*
3718 * This operation locks against the VM for all pte/vma/mm related
3719 * operations that could ever happen on a certain mm. This includes
3720 * vmtruncate, try_to_unmap, and all page faults.
3721 *
3722 * The caller must take the mmap_lock in write mode before calling
3723 * mm_take_all_locks(). The caller isn't allowed to release the
3724 * mmap_lock until mm_drop_all_locks() returns.
3725 *
3726 * mmap_lock in write mode is required in order to block all operations
3727 * that could modify pagetables and free pages without need of
3728 * altering the vma layout. It's also needed in write mode to avoid new
3729 * anon_vmas to be associated with existing vmas.
3730 *
3731 * A single task can't take more than one mm_take_all_locks() in a row
3732 * or it would deadlock.
3733 *
3734 * The LSB in anon_vma->rb_root.rb_node and the AS_MM_ALL_LOCKS bitflag in
3735 * mapping->flags avoid to take the same lock twice, if more than one
3736 * vma in this mm is backed by the same anon_vma or address_space.
3737 *
3738 * We take locks in following order, accordingly to comment at beginning
3739 * of mm/rmap.c:
3740 * - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
3741 * hugetlb mapping);
3742 * - all vmas marked locked
3743 * - all i_mmap_rwsem locks;
3744 * - all anon_vma->rwseml
3745 *
3746 * We can take all locks within these types randomly because the VM code
3747 * doesn't nest them and we protected from parallel mm_take_all_locks() by
3748 * mm_all_locks_mutex.
3749 *
3750 * mm_take_all_locks() and mm_drop_all_locks are expensive operations
3751 * that may have to take thousand of locks.
3752 *
3753 * mm_take_all_locks() can fail if it's interrupted by signals.
3754 */
3755int mm_take_all_locks(struct mm_struct *mm)
3756{
3757 struct vm_area_struct *vma;
3758 struct anon_vma_chain *avc;
3759 MA_STATE(mas, &mm->mm_mt, 0, 0);
3760
3761 mmap_assert_write_locked(mm);
3762
3763 mutex_lock(&mm_all_locks_mutex);
3764
3765 /*
3766 * vma_start_write() does not have a complement in mm_drop_all_locks()
3767 * because vma_start_write() is always asymmetrical; it marks a VMA as
3768 * being written to until mmap_write_unlock() or mmap_write_downgrade()
3769 * is reached.
3770 */
3771 mas_for_each(&mas, vma, ULONG_MAX) {
3772 if (signal_pending(current))
3773 goto out_unlock;
3774 vma_start_write(vma);
3775 }
3776
3777 mas_set(mas: &mas, index: 0);
3778 mas_for_each(&mas, vma, ULONG_MAX) {
3779 if (signal_pending(current))
3780 goto out_unlock;
3781 if (vma->vm_file && vma->vm_file->f_mapping &&
3782 is_vm_hugetlb_page(vma))
3783 vm_lock_mapping(mm, mapping: vma->vm_file->f_mapping);
3784 }
3785
3786 mas_set(mas: &mas, index: 0);
3787 mas_for_each(&mas, vma, ULONG_MAX) {
3788 if (signal_pending(current))
3789 goto out_unlock;
3790 if (vma->vm_file && vma->vm_file->f_mapping &&
3791 !is_vm_hugetlb_page(vma))
3792 vm_lock_mapping(mm, mapping: vma->vm_file->f_mapping);
3793 }
3794
3795 mas_set(mas: &mas, index: 0);
3796 mas_for_each(&mas, vma, ULONG_MAX) {
3797 if (signal_pending(current))
3798 goto out_unlock;
3799 if (vma->anon_vma)
3800 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3801 vm_lock_anon_vma(mm, anon_vma: avc->anon_vma);
3802 }
3803
3804 return 0;
3805
3806out_unlock:
3807 mm_drop_all_locks(mm);
3808 return -EINTR;
3809}
3810
3811static void vm_unlock_anon_vma(struct anon_vma *anon_vma)
3812{
3813 if (test_bit(0, (unsigned long *) &anon_vma->root->rb_root.rb_root.rb_node)) {
3814 /*
3815 * The LSB of head.next can't change to 0 from under
3816 * us because we hold the mm_all_locks_mutex.
3817 *
3818 * We must however clear the bitflag before unlocking
3819 * the vma so the users using the anon_vma->rb_root will
3820 * never see our bitflag.
3821 *
3822 * No need of atomic instructions here, head.next
3823 * can't change from under us until we release the
3824 * anon_vma->root->rwsem.
3825 */
3826 if (!__test_and_clear_bit(0, (unsigned long *)
3827 &anon_vma->root->rb_root.rb_root.rb_node))
3828 BUG();
3829 anon_vma_unlock_write(anon_vma);
3830 }
3831}
3832
3833static void vm_unlock_mapping(struct address_space *mapping)
3834{
3835 if (test_bit(AS_MM_ALL_LOCKS, &mapping->flags)) {
3836 /*
3837 * AS_MM_ALL_LOCKS can't change to 0 from under us
3838 * because we hold the mm_all_locks_mutex.
3839 */
3840 i_mmap_unlock_write(mapping);
3841 if (!test_and_clear_bit(nr: AS_MM_ALL_LOCKS,
3842 addr: &mapping->flags))
3843 BUG();
3844 }
3845}
3846
3847/*
3848 * The mmap_lock cannot be released by the caller until
3849 * mm_drop_all_locks() returns.
3850 */
3851void mm_drop_all_locks(struct mm_struct *mm)
3852{
3853 struct vm_area_struct *vma;
3854 struct anon_vma_chain *avc;
3855 MA_STATE(mas, &mm->mm_mt, 0, 0);
3856
3857 mmap_assert_write_locked(mm);
3858 BUG_ON(!mutex_is_locked(&mm_all_locks_mutex));
3859
3860 mas_for_each(&mas, vma, ULONG_MAX) {
3861 if (vma->anon_vma)
3862 list_for_each_entry(avc, &vma->anon_vma_chain, same_vma)
3863 vm_unlock_anon_vma(anon_vma: avc->anon_vma);
3864 if (vma->vm_file && vma->vm_file->f_mapping)
3865 vm_unlock_mapping(mapping: vma->vm_file->f_mapping);
3866 }
3867
3868 mutex_unlock(lock: &mm_all_locks_mutex);
3869}
3870
3871/*
3872 * initialise the percpu counter for VM
3873 */
3874void __init mmap_init(void)
3875{
3876 int ret;
3877
3878 ret = percpu_counter_init(&vm_committed_as, 0, GFP_KERNEL);
3879 VM_BUG_ON(ret);
3880}
3881
3882/*
3883 * Initialise sysctl_user_reserve_kbytes.
3884 *
3885 * This is intended to prevent a user from starting a single memory hogging
3886 * process, such that they cannot recover (kill the hog) in OVERCOMMIT_NEVER
3887 * mode.
3888 *
3889 * The default value is min(3% of free memory, 128MB)
3890 * 128MB is enough to recover with sshd/login, bash, and top/kill.
3891 */
3892static int init_user_reserve(void)
3893{
3894 unsigned long free_kbytes;
3895
3896 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
3897
3898 sysctl_user_reserve_kbytes = min(free_kbytes / 32, 1UL << 17);
3899 return 0;
3900}
3901subsys_initcall(init_user_reserve);
3902
3903/*
3904 * Initialise sysctl_admin_reserve_kbytes.
3905 *
3906 * The purpose of sysctl_admin_reserve_kbytes is to allow the sys admin
3907 * to log in and kill a memory hogging process.
3908 *
3909 * Systems with more than 256MB will reserve 8MB, enough to recover
3910 * with sshd, bash, and top in OVERCOMMIT_GUESS. Smaller systems will
3911 * only reserve 3% of free pages by default.
3912 */
3913static int init_admin_reserve(void)
3914{
3915 unsigned long free_kbytes;
3916
3917 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
3918
3919 sysctl_admin_reserve_kbytes = min(free_kbytes / 32, 1UL << 13);
3920 return 0;
3921}
3922subsys_initcall(init_admin_reserve);
3923
3924/*
3925 * Reinititalise user and admin reserves if memory is added or removed.
3926 *
3927 * The default user reserve max is 128MB, and the default max for the
3928 * admin reserve is 8MB. These are usually, but not always, enough to
3929 * enable recovery from a memory hogging process using login/sshd, a shell,
3930 * and tools like top. It may make sense to increase or even disable the
3931 * reserve depending on the existence of swap or variations in the recovery
3932 * tools. So, the admin may have changed them.
3933 *
3934 * If memory is added and the reserves have been eliminated or increased above
3935 * the default max, then we'll trust the admin.
3936 *
3937 * If memory is removed and there isn't enough free memory, then we
3938 * need to reset the reserves.
3939 *
3940 * Otherwise keep the reserve set by the admin.
3941 */
3942static int reserve_mem_notifier(struct notifier_block *nb,
3943 unsigned long action, void *data)
3944{
3945 unsigned long tmp, free_kbytes;
3946
3947 switch (action) {
3948 case MEM_ONLINE:
3949 /* Default max is 128MB. Leave alone if modified by operator. */
3950 tmp = sysctl_user_reserve_kbytes;
3951 if (0 < tmp && tmp < (1UL << 17))
3952 init_user_reserve();
3953
3954 /* Default max is 8MB. Leave alone if modified by operator. */
3955 tmp = sysctl_admin_reserve_kbytes;
3956 if (0 < tmp && tmp < (1UL << 13))
3957 init_admin_reserve();
3958
3959 break;
3960 case MEM_OFFLINE:
3961 free_kbytes = K(global_zone_page_state(NR_FREE_PAGES));
3962
3963 if (sysctl_user_reserve_kbytes > free_kbytes) {
3964 init_user_reserve();
3965 pr_info("vm.user_reserve_kbytes reset to %lu\n",
3966 sysctl_user_reserve_kbytes);
3967 }
3968
3969 if (sysctl_admin_reserve_kbytes > free_kbytes) {
3970 init_admin_reserve();
3971 pr_info("vm.admin_reserve_kbytes reset to %lu\n",
3972 sysctl_admin_reserve_kbytes);
3973 }
3974 break;
3975 default:
3976 break;
3977 }
3978 return NOTIFY_OK;
3979}
3980
3981static int __meminit init_reserve_notifier(void)
3982{
3983 if (hotplug_memory_notifier(reserve_mem_notifier, DEFAULT_CALLBACK_PRI))
3984 pr_err("Failed registering memory add/remove notifier for admin reserve\n");
3985
3986 return 0;
3987}
3988subsys_initcall(init_reserve_notifier);
3989

source code of linux/mm/mmap.c