1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/madvise.c
4 *
5 * Copyright (C) 1999 Linus Torvalds
6 * Copyright (C) 2002 Christoph Hellwig
7 */
8
9#include <linux/mman.h>
10#include <linux/pagemap.h>
11#include <linux/syscalls.h>
12#include <linux/mempolicy.h>
13#include <linux/page-isolation.h>
14#include <linux/page_idle.h>
15#include <linux/userfaultfd_k.h>
16#include <linux/hugetlb.h>
17#include <linux/falloc.h>
18#include <linux/fadvise.h>
19#include <linux/sched.h>
20#include <linux/sched/mm.h>
21#include <linux/mm_inline.h>
22#include <linux/string.h>
23#include <linux/uio.h>
24#include <linux/ksm.h>
25#include <linux/fs.h>
26#include <linux/file.h>
27#include <linux/blkdev.h>
28#include <linux/backing-dev.h>
29#include <linux/pagewalk.h>
30#include <linux/swap.h>
31#include <linux/swapops.h>
32#include <linux/shmem_fs.h>
33#include <linux/mmu_notifier.h>
34
35#include <asm/tlb.h>
36
37#include "internal.h"
38#include "swap.h"
39
40struct madvise_walk_private {
41 struct mmu_gather *tlb;
42 bool pageout;
43};
44
45/*
46 * Any behaviour which results in changes to the vma->vm_flags needs to
47 * take mmap_lock for writing. Others, which simply traverse vmas, need
48 * to only take it for reading.
49 */
50static int madvise_need_mmap_write(int behavior)
51{
52 switch (behavior) {
53 case MADV_REMOVE:
54 case MADV_WILLNEED:
55 case MADV_DONTNEED:
56 case MADV_DONTNEED_LOCKED:
57 case MADV_COLD:
58 case MADV_PAGEOUT:
59 case MADV_FREE:
60 case MADV_POPULATE_READ:
61 case MADV_POPULATE_WRITE:
62 case MADV_COLLAPSE:
63 return 0;
64 default:
65 /* be safe, default to 1. list exceptions explicitly */
66 return 1;
67 }
68}
69
70#ifdef CONFIG_ANON_VMA_NAME
71struct anon_vma_name *anon_vma_name_alloc(const char *name)
72{
73 struct anon_vma_name *anon_name;
74 size_t count;
75
76 /* Add 1 for NUL terminator at the end of the anon_name->name */
77 count = strlen(name) + 1;
78 anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
79 if (anon_name) {
80 kref_init(kref: &anon_name->kref);
81 memcpy(anon_name->name, name, count);
82 }
83
84 return anon_name;
85}
86
87void anon_vma_name_free(struct kref *kref)
88{
89 struct anon_vma_name *anon_name =
90 container_of(kref, struct anon_vma_name, kref);
91 kfree(objp: anon_name);
92}
93
94struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
95{
96 mmap_assert_locked(mm: vma->vm_mm);
97
98 return vma->anon_name;
99}
100
101/* mmap_lock should be write-locked */
102static int replace_anon_vma_name(struct vm_area_struct *vma,
103 struct anon_vma_name *anon_name)
104{
105 struct anon_vma_name *orig_name = anon_vma_name(vma);
106
107 if (!anon_name) {
108 vma->anon_name = NULL;
109 anon_vma_name_put(anon_name: orig_name);
110 return 0;
111 }
112
113 if (anon_vma_name_eq(anon_name1: orig_name, anon_name2: anon_name))
114 return 0;
115
116 vma->anon_name = anon_vma_name_reuse(anon_name);
117 anon_vma_name_put(anon_name: orig_name);
118
119 return 0;
120}
121#else /* CONFIG_ANON_VMA_NAME */
122static int replace_anon_vma_name(struct vm_area_struct *vma,
123 struct anon_vma_name *anon_name)
124{
125 if (anon_name)
126 return -EINVAL;
127
128 return 0;
129}
130#endif /* CONFIG_ANON_VMA_NAME */
131/*
132 * Update the vm_flags on region of a vma, splitting it or merging it as
133 * necessary. Must be called with mmap_lock held for writing;
134 * Caller should ensure anon_name stability by raising its refcount even when
135 * anon_name belongs to a valid vma because this function might free that vma.
136 */
137static int madvise_update_vma(struct vm_area_struct *vma,
138 struct vm_area_struct **prev, unsigned long start,
139 unsigned long end, unsigned long new_flags,
140 struct anon_vma_name *anon_name)
141{
142 struct mm_struct *mm = vma->vm_mm;
143 int error;
144 VMA_ITERATOR(vmi, mm, start);
145
146 if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_name1: anon_vma_name(vma), anon_name2: anon_name)) {
147 *prev = vma;
148 return 0;
149 }
150
151 vma = vma_modify_flags_name(vmi: &vmi, prev: *prev, vma, start, end, new_flags,
152 new_name: anon_name);
153 if (IS_ERR(ptr: vma))
154 return PTR_ERR(ptr: vma);
155
156 *prev = vma;
157
158 /* vm_flags is protected by the mmap_lock held in write mode. */
159 vma_start_write(vma);
160 vm_flags_reset(vma, flags: new_flags);
161 if (!vma->vm_file || vma_is_anon_shmem(vma)) {
162 error = replace_anon_vma_name(vma, anon_name);
163 if (error)
164 return error;
165 }
166
167 return 0;
168}
169
170#ifdef CONFIG_SWAP
171static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
172 unsigned long end, struct mm_walk *walk)
173{
174 struct vm_area_struct *vma = walk->private;
175 struct swap_iocb *splug = NULL;
176 pte_t *ptep = NULL;
177 spinlock_t *ptl;
178 unsigned long addr;
179
180 for (addr = start; addr < end; addr += PAGE_SIZE) {
181 pte_t pte;
182 swp_entry_t entry;
183 struct page *page;
184
185 if (!ptep++) {
186 ptep = pte_offset_map_lock(mm: vma->vm_mm, pmd, addr, ptlp: &ptl);
187 if (!ptep)
188 break;
189 }
190
191 pte = ptep_get(ptep);
192 if (!is_swap_pte(pte))
193 continue;
194 entry = pte_to_swp_entry(pte);
195 if (unlikely(non_swap_entry(entry)))
196 continue;
197
198 pte_unmap_unlock(ptep, ptl);
199 ptep = NULL;
200
201 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
202 vma, addr, plug: &splug);
203 if (page)
204 put_page(page);
205 }
206
207 if (ptep)
208 pte_unmap_unlock(ptep, ptl);
209 swap_read_unplug(plug: splug);
210 cond_resched();
211
212 return 0;
213}
214
215static const struct mm_walk_ops swapin_walk_ops = {
216 .pmd_entry = swapin_walk_pmd_entry,
217 .walk_lock = PGWALK_RDLOCK,
218};
219
220static void shmem_swapin_range(struct vm_area_struct *vma,
221 unsigned long start, unsigned long end,
222 struct address_space *mapping)
223{
224 XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
225 pgoff_t end_index = linear_page_index(vma, address: end) - 1;
226 struct page *page;
227 struct swap_iocb *splug = NULL;
228
229 rcu_read_lock();
230 xas_for_each(&xas, page, end_index) {
231 unsigned long addr;
232 swp_entry_t entry;
233
234 if (!xa_is_value(entry: page))
235 continue;
236 entry = radix_to_swp_entry(arg: page);
237 /* There might be swapin error entries in shmem mapping. */
238 if (non_swap_entry(entry))
239 continue;
240
241 addr = vma->vm_start +
242 ((xas.xa_index - vma->vm_pgoff) << PAGE_SHIFT);
243 xas_pause(&xas);
244 rcu_read_unlock();
245
246 page = read_swap_cache_async(entry, gfp_mask: mapping_gfp_mask(mapping),
247 vma, addr, plug: &splug);
248 if (page)
249 put_page(page);
250
251 rcu_read_lock();
252 }
253 rcu_read_unlock();
254 swap_read_unplug(plug: splug);
255}
256#endif /* CONFIG_SWAP */
257
258/*
259 * Schedule all required I/O operations. Do not wait for completion.
260 */
261static long madvise_willneed(struct vm_area_struct *vma,
262 struct vm_area_struct **prev,
263 unsigned long start, unsigned long end)
264{
265 struct mm_struct *mm = vma->vm_mm;
266 struct file *file = vma->vm_file;
267 loff_t offset;
268
269 *prev = vma;
270#ifdef CONFIG_SWAP
271 if (!file) {
272 walk_page_range(mm: vma->vm_mm, start, end, ops: &swapin_walk_ops, private: vma);
273 lru_add_drain(); /* Push any new pages onto the LRU now */
274 return 0;
275 }
276
277 if (shmem_mapping(mapping: file->f_mapping)) {
278 shmem_swapin_range(vma, start, end, mapping: file->f_mapping);
279 lru_add_drain(); /* Push any new pages onto the LRU now */
280 return 0;
281 }
282#else
283 if (!file)
284 return -EBADF;
285#endif
286
287 if (IS_DAX(file_inode(file))) {
288 /* no bad return value, but ignore advice */
289 return 0;
290 }
291
292 /*
293 * Filesystem's fadvise may need to take various locks. We need to
294 * explicitly grab a reference because the vma (and hence the
295 * vma's reference to the file) can go away as soon as we drop
296 * mmap_lock.
297 */
298 *prev = NULL; /* tell sys_madvise we drop mmap_lock */
299 get_file(f: file);
300 offset = (loff_t)(start - vma->vm_start)
301 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
302 mmap_read_unlock(mm);
303 vfs_fadvise(file, offset, len: end - start, POSIX_FADV_WILLNEED);
304 fput(file);
305 mmap_read_lock(mm);
306 return 0;
307}
308
309static inline bool can_do_file_pageout(struct vm_area_struct *vma)
310{
311 if (!vma->vm_file)
312 return false;
313 /*
314 * paging out pagecache only for non-anonymous mappings that correspond
315 * to the files the calling process could (if tried) open for writing;
316 * otherwise we'd be including shared non-exclusive mappings, which
317 * opens a side channel.
318 */
319 return inode_owner_or_capable(idmap: &nop_mnt_idmap,
320 inode: file_inode(f: vma->vm_file)) ||
321 file_permission(file: vma->vm_file, MAY_WRITE) == 0;
322}
323
324static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
325 unsigned long addr, unsigned long end,
326 struct mm_walk *walk)
327{
328 struct madvise_walk_private *private = walk->private;
329 struct mmu_gather *tlb = private->tlb;
330 bool pageout = private->pageout;
331 struct mm_struct *mm = tlb->mm;
332 struct vm_area_struct *vma = walk->vma;
333 pte_t *start_pte, *pte, ptent;
334 spinlock_t *ptl;
335 struct folio *folio = NULL;
336 LIST_HEAD(folio_list);
337 bool pageout_anon_only_filter;
338
339 if (fatal_signal_pending(current))
340 return -EINTR;
341
342 pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
343 !can_do_file_pageout(vma);
344
345#ifdef CONFIG_TRANSPARENT_HUGEPAGE
346 if (pmd_trans_huge(pmd: *pmd)) {
347 pmd_t orig_pmd;
348 unsigned long next = pmd_addr_end(addr, end);
349
350 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
351 ptl = pmd_trans_huge_lock(pmd, vma);
352 if (!ptl)
353 return 0;
354
355 orig_pmd = *pmd;
356 if (is_huge_zero_pmd(pmd: orig_pmd))
357 goto huge_unlock;
358
359 if (unlikely(!pmd_present(orig_pmd))) {
360 VM_BUG_ON(thp_migration_supported() &&
361 !is_pmd_migration_entry(orig_pmd));
362 goto huge_unlock;
363 }
364
365 folio = pfn_folio(pfn: pmd_pfn(pmd: orig_pmd));
366
367 /* Do not interfere with other mappings of this folio */
368 if (folio_estimated_sharers(folio) != 1)
369 goto huge_unlock;
370
371 if (pageout_anon_only_filter && !folio_test_anon(folio))
372 goto huge_unlock;
373
374 if (next - addr != HPAGE_PMD_SIZE) {
375 int err;
376
377 folio_get(folio);
378 spin_unlock(lock: ptl);
379 folio_lock(folio);
380 err = split_folio(folio);
381 folio_unlock(folio);
382 folio_put(folio);
383 if (!err)
384 goto regular_folio;
385 return 0;
386 }
387
388 if (pmd_young(pmd: orig_pmd)) {
389 pmdp_invalidate(vma, address: addr, pmdp: pmd);
390 orig_pmd = pmd_mkold(pmd: orig_pmd);
391
392 set_pmd_at(mm, addr, pmdp: pmd, pmd: orig_pmd);
393 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
394 }
395
396 folio_clear_referenced(folio);
397 folio_test_clear_young(folio);
398 if (folio_test_active(folio))
399 folio_set_workingset(folio);
400 if (pageout) {
401 if (folio_isolate_lru(folio)) {
402 if (folio_test_unevictable(folio))
403 folio_putback_lru(folio);
404 else
405 list_add(new: &folio->lru, head: &folio_list);
406 }
407 } else
408 folio_deactivate(folio);
409huge_unlock:
410 spin_unlock(lock: ptl);
411 if (pageout)
412 reclaim_pages(folio_list: &folio_list);
413 return 0;
414 }
415
416regular_folio:
417#endif
418 tlb_change_page_size(tlb, PAGE_SIZE);
419 start_pte = pte = pte_offset_map_lock(mm: vma->vm_mm, pmd, addr, ptlp: &ptl);
420 if (!start_pte)
421 return 0;
422 flush_tlb_batched_pending(mm);
423 arch_enter_lazy_mmu_mode();
424 for (; addr < end; pte++, addr += PAGE_SIZE) {
425 ptent = ptep_get(ptep: pte);
426
427 if (pte_none(pte: ptent))
428 continue;
429
430 if (!pte_present(a: ptent))
431 continue;
432
433 folio = vm_normal_folio(vma, addr, pte: ptent);
434 if (!folio || folio_is_zone_device(folio))
435 continue;
436
437 /*
438 * Creating a THP page is expensive so split it only if we
439 * are sure it's worth. Split it if we are only owner.
440 */
441 if (folio_test_large(folio)) {
442 int err;
443
444 if (folio_estimated_sharers(folio) != 1)
445 break;
446 if (pageout_anon_only_filter && !folio_test_anon(folio))
447 break;
448 if (!folio_trylock(folio))
449 break;
450 folio_get(folio);
451 arch_leave_lazy_mmu_mode();
452 pte_unmap_unlock(start_pte, ptl);
453 start_pte = NULL;
454 err = split_folio(folio);
455 folio_unlock(folio);
456 folio_put(folio);
457 if (err)
458 break;
459 start_pte = pte =
460 pte_offset_map_lock(mm, pmd, addr, ptlp: &ptl);
461 if (!start_pte)
462 break;
463 arch_enter_lazy_mmu_mode();
464 pte--;
465 addr -= PAGE_SIZE;
466 continue;
467 }
468
469 /*
470 * Do not interfere with other mappings of this folio and
471 * non-LRU folio.
472 */
473 if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
474 continue;
475
476 if (pageout_anon_only_filter && !folio_test_anon(folio))
477 continue;
478
479 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
480
481 if (pte_young(pte: ptent)) {
482 ptent = ptep_get_and_clear_full(mm, addr, ptep: pte,
483 full: tlb->fullmm);
484 ptent = pte_mkold(pte: ptent);
485 set_pte_at(mm, addr, pte, ptent);
486 tlb_remove_tlb_entry(tlb, pte, addr);
487 }
488
489 /*
490 * We are deactivating a folio for accelerating reclaiming.
491 * VM couldn't reclaim the folio unless we clear PG_young.
492 * As a side effect, it makes confuse idle-page tracking
493 * because they will miss recent referenced history.
494 */
495 folio_clear_referenced(folio);
496 folio_test_clear_young(folio);
497 if (folio_test_active(folio))
498 folio_set_workingset(folio);
499 if (pageout) {
500 if (folio_isolate_lru(folio)) {
501 if (folio_test_unevictable(folio))
502 folio_putback_lru(folio);
503 else
504 list_add(new: &folio->lru, head: &folio_list);
505 }
506 } else
507 folio_deactivate(folio);
508 }
509
510 if (start_pte) {
511 arch_leave_lazy_mmu_mode();
512 pte_unmap_unlock(start_pte, ptl);
513 }
514 if (pageout)
515 reclaim_pages(folio_list: &folio_list);
516 cond_resched();
517
518 return 0;
519}
520
521static const struct mm_walk_ops cold_walk_ops = {
522 .pmd_entry = madvise_cold_or_pageout_pte_range,
523 .walk_lock = PGWALK_RDLOCK,
524};
525
526static void madvise_cold_page_range(struct mmu_gather *tlb,
527 struct vm_area_struct *vma,
528 unsigned long addr, unsigned long end)
529{
530 struct madvise_walk_private walk_private = {
531 .pageout = false,
532 .tlb = tlb,
533 };
534
535 tlb_start_vma(tlb, vma);
536 walk_page_range(mm: vma->vm_mm, start: addr, end, ops: &cold_walk_ops, private: &walk_private);
537 tlb_end_vma(tlb, vma);
538}
539
540static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
541{
542 return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
543}
544
545static long madvise_cold(struct vm_area_struct *vma,
546 struct vm_area_struct **prev,
547 unsigned long start_addr, unsigned long end_addr)
548{
549 struct mm_struct *mm = vma->vm_mm;
550 struct mmu_gather tlb;
551
552 *prev = vma;
553 if (!can_madv_lru_vma(vma))
554 return -EINVAL;
555
556 lru_add_drain();
557 tlb_gather_mmu(tlb: &tlb, mm);
558 madvise_cold_page_range(tlb: &tlb, vma, addr: start_addr, end: end_addr);
559 tlb_finish_mmu(tlb: &tlb);
560
561 return 0;
562}
563
564static void madvise_pageout_page_range(struct mmu_gather *tlb,
565 struct vm_area_struct *vma,
566 unsigned long addr, unsigned long end)
567{
568 struct madvise_walk_private walk_private = {
569 .pageout = true,
570 .tlb = tlb,
571 };
572
573 tlb_start_vma(tlb, vma);
574 walk_page_range(mm: vma->vm_mm, start: addr, end, ops: &cold_walk_ops, private: &walk_private);
575 tlb_end_vma(tlb, vma);
576}
577
578static long madvise_pageout(struct vm_area_struct *vma,
579 struct vm_area_struct **prev,
580 unsigned long start_addr, unsigned long end_addr)
581{
582 struct mm_struct *mm = vma->vm_mm;
583 struct mmu_gather tlb;
584
585 *prev = vma;
586 if (!can_madv_lru_vma(vma))
587 return -EINVAL;
588
589 /*
590 * If the VMA belongs to a private file mapping, there can be private
591 * dirty pages which can be paged out if even this process is neither
592 * owner nor write capable of the file. We allow private file mappings
593 * further to pageout dirty anon pages.
594 */
595 if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
596 (vma->vm_flags & VM_MAYSHARE)))
597 return 0;
598
599 lru_add_drain();
600 tlb_gather_mmu(tlb: &tlb, mm);
601 madvise_pageout_page_range(tlb: &tlb, vma, addr: start_addr, end: end_addr);
602 tlb_finish_mmu(tlb: &tlb);
603
604 return 0;
605}
606
607static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
608 unsigned long end, struct mm_walk *walk)
609
610{
611 struct mmu_gather *tlb = walk->private;
612 struct mm_struct *mm = tlb->mm;
613 struct vm_area_struct *vma = walk->vma;
614 spinlock_t *ptl;
615 pte_t *start_pte, *pte, ptent;
616 struct folio *folio;
617 int nr_swap = 0;
618 unsigned long next;
619
620 next = pmd_addr_end(addr, end);
621 if (pmd_trans_huge(pmd: *pmd))
622 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
623 return 0;
624
625 tlb_change_page_size(tlb, PAGE_SIZE);
626 start_pte = pte = pte_offset_map_lock(mm, pmd, addr, ptlp: &ptl);
627 if (!start_pte)
628 return 0;
629 flush_tlb_batched_pending(mm);
630 arch_enter_lazy_mmu_mode();
631 for (; addr != end; pte++, addr += PAGE_SIZE) {
632 ptent = ptep_get(ptep: pte);
633
634 if (pte_none(pte: ptent))
635 continue;
636 /*
637 * If the pte has swp_entry, just clear page table to
638 * prevent swap-in which is more expensive rather than
639 * (page allocation + zeroing).
640 */
641 if (!pte_present(a: ptent)) {
642 swp_entry_t entry;
643
644 entry = pte_to_swp_entry(pte: ptent);
645 if (!non_swap_entry(entry)) {
646 nr_swap--;
647 free_swap_and_cache(entry);
648 pte_clear_not_present_full(mm, address: addr, ptep: pte, full: tlb->fullmm);
649 } else if (is_hwpoison_entry(entry) ||
650 is_poisoned_swp_entry(entry)) {
651 pte_clear_not_present_full(mm, address: addr, ptep: pte, full: tlb->fullmm);
652 }
653 continue;
654 }
655
656 folio = vm_normal_folio(vma, addr, pte: ptent);
657 if (!folio || folio_is_zone_device(folio))
658 continue;
659
660 /*
661 * If pmd isn't transhuge but the folio is large and
662 * is owned by only this process, split it and
663 * deactivate all pages.
664 */
665 if (folio_test_large(folio)) {
666 int err;
667
668 if (folio_estimated_sharers(folio) != 1)
669 break;
670 if (!folio_trylock(folio))
671 break;
672 folio_get(folio);
673 arch_leave_lazy_mmu_mode();
674 pte_unmap_unlock(start_pte, ptl);
675 start_pte = NULL;
676 err = split_folio(folio);
677 folio_unlock(folio);
678 folio_put(folio);
679 if (err)
680 break;
681 start_pte = pte =
682 pte_offset_map_lock(mm, pmd, addr, ptlp: &ptl);
683 if (!start_pte)
684 break;
685 arch_enter_lazy_mmu_mode();
686 pte--;
687 addr -= PAGE_SIZE;
688 continue;
689 }
690
691 if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
692 if (!folio_trylock(folio))
693 continue;
694 /*
695 * If folio is shared with others, we mustn't clear
696 * the folio's dirty flag.
697 */
698 if (folio_mapcount(folio) != 1) {
699 folio_unlock(folio);
700 continue;
701 }
702
703 if (folio_test_swapcache(folio) &&
704 !folio_free_swap(folio)) {
705 folio_unlock(folio);
706 continue;
707 }
708
709 folio_clear_dirty(folio);
710 folio_unlock(folio);
711 }
712
713 if (pte_young(pte: ptent) || pte_dirty(pte: ptent)) {
714 /*
715 * Some of architecture(ex, PPC) don't update TLB
716 * with set_pte_at and tlb_remove_tlb_entry so for
717 * the portability, remap the pte with old|clean
718 * after pte clearing.
719 */
720 ptent = ptep_get_and_clear_full(mm, addr, ptep: pte,
721 full: tlb->fullmm);
722
723 ptent = pte_mkold(pte: ptent);
724 ptent = pte_mkclean(pte: ptent);
725 set_pte_at(mm, addr, pte, ptent);
726 tlb_remove_tlb_entry(tlb, pte, addr);
727 }
728 folio_mark_lazyfree(folio);
729 }
730
731 if (nr_swap)
732 add_mm_counter(mm, member: MM_SWAPENTS, value: nr_swap);
733 if (start_pte) {
734 arch_leave_lazy_mmu_mode();
735 pte_unmap_unlock(start_pte, ptl);
736 }
737 cond_resched();
738
739 return 0;
740}
741
742static const struct mm_walk_ops madvise_free_walk_ops = {
743 .pmd_entry = madvise_free_pte_range,
744 .walk_lock = PGWALK_RDLOCK,
745};
746
747static int madvise_free_single_vma(struct vm_area_struct *vma,
748 unsigned long start_addr, unsigned long end_addr)
749{
750 struct mm_struct *mm = vma->vm_mm;
751 struct mmu_notifier_range range;
752 struct mmu_gather tlb;
753
754 /* MADV_FREE works for only anon vma at the moment */
755 if (!vma_is_anonymous(vma))
756 return -EINVAL;
757
758 range.start = max(vma->vm_start, start_addr);
759 if (range.start >= vma->vm_end)
760 return -EINVAL;
761 range.end = min(vma->vm_end, end_addr);
762 if (range.end <= vma->vm_start)
763 return -EINVAL;
764 mmu_notifier_range_init(range: &range, event: MMU_NOTIFY_CLEAR, flags: 0, mm,
765 start: range.start, end: range.end);
766
767 lru_add_drain();
768 tlb_gather_mmu(tlb: &tlb, mm);
769 update_hiwater_rss(mm);
770
771 mmu_notifier_invalidate_range_start(range: &range);
772 tlb_start_vma(tlb: &tlb, vma);
773 walk_page_range(mm: vma->vm_mm, start: range.start, end: range.end,
774 ops: &madvise_free_walk_ops, private: &tlb);
775 tlb_end_vma(tlb: &tlb, vma);
776 mmu_notifier_invalidate_range_end(range: &range);
777 tlb_finish_mmu(tlb: &tlb);
778
779 return 0;
780}
781
782/*
783 * Application no longer needs these pages. If the pages are dirty,
784 * it's OK to just throw them away. The app will be more careful about
785 * data it wants to keep. Be sure to free swap resources too. The
786 * zap_page_range_single call sets things up for shrink_active_list to actually
787 * free these pages later if no one else has touched them in the meantime,
788 * although we could add these pages to a global reuse list for
789 * shrink_active_list to pick up before reclaiming other pages.
790 *
791 * NB: This interface discards data rather than pushes it out to swap,
792 * as some implementations do. This has performance implications for
793 * applications like large transactional databases which want to discard
794 * pages in anonymous maps after committing to backing store the data
795 * that was kept in them. There is no reason to write this data out to
796 * the swap area if the application is discarding it.
797 *
798 * An interface that causes the system to free clean pages and flush
799 * dirty pages is already available as msync(MS_INVALIDATE).
800 */
801static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
802 unsigned long start, unsigned long end)
803{
804 zap_page_range_single(vma, address: start, size: end - start, NULL);
805 return 0;
806}
807
808static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
809 unsigned long start,
810 unsigned long *end,
811 int behavior)
812{
813 if (!is_vm_hugetlb_page(vma)) {
814 unsigned int forbidden = VM_PFNMAP;
815
816 if (behavior != MADV_DONTNEED_LOCKED)
817 forbidden |= VM_LOCKED;
818
819 return !(vma->vm_flags & forbidden);
820 }
821
822 if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
823 return false;
824 if (start & ~huge_page_mask(h: hstate_vma(vma)))
825 return false;
826
827 /*
828 * Madvise callers expect the length to be rounded up to PAGE_SIZE
829 * boundaries, and may be unaware that this VMA uses huge pages.
830 * Avoid unexpected data loss by rounding down the number of
831 * huge pages freed.
832 */
833 *end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
834
835 return true;
836}
837
838static long madvise_dontneed_free(struct vm_area_struct *vma,
839 struct vm_area_struct **prev,
840 unsigned long start, unsigned long end,
841 int behavior)
842{
843 struct mm_struct *mm = vma->vm_mm;
844
845 *prev = vma;
846 if (!madvise_dontneed_free_valid_vma(vma, start, end: &end, behavior))
847 return -EINVAL;
848
849 if (start == end)
850 return 0;
851
852 if (!userfaultfd_remove(vma, start, end)) {
853 *prev = NULL; /* mmap_lock has been dropped, prev is stale */
854
855 mmap_read_lock(mm);
856 vma = vma_lookup(mm, addr: start);
857 if (!vma)
858 return -ENOMEM;
859 /*
860 * Potential end adjustment for hugetlb vma is OK as
861 * the check below keeps end within vma.
862 */
863 if (!madvise_dontneed_free_valid_vma(vma, start, end: &end,
864 behavior))
865 return -EINVAL;
866 if (end > vma->vm_end) {
867 /*
868 * Don't fail if end > vma->vm_end. If the old
869 * vma was split while the mmap_lock was
870 * released the effect of the concurrent
871 * operation may not cause madvise() to
872 * have an undefined result. There may be an
873 * adjacent next vma that we'll walk
874 * next. userfaultfd_remove() will generate an
875 * UFFD_EVENT_REMOVE repetition on the
876 * end-vma->vm_end range, but the manager can
877 * handle a repetition fine.
878 */
879 end = vma->vm_end;
880 }
881 VM_WARN_ON(start >= end);
882 }
883
884 if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
885 return madvise_dontneed_single_vma(vma, start, end);
886 else if (behavior == MADV_FREE)
887 return madvise_free_single_vma(vma, start_addr: start, end_addr: end);
888 else
889 return -EINVAL;
890}
891
892static long madvise_populate(struct vm_area_struct *vma,
893 struct vm_area_struct **prev,
894 unsigned long start, unsigned long end,
895 int behavior)
896{
897 const bool write = behavior == MADV_POPULATE_WRITE;
898 struct mm_struct *mm = vma->vm_mm;
899 unsigned long tmp_end;
900 int locked = 1;
901 long pages;
902
903 *prev = vma;
904
905 while (start < end) {
906 /*
907 * We might have temporarily dropped the lock. For example,
908 * our VMA might have been split.
909 */
910 if (!vma || start >= vma->vm_end) {
911 vma = vma_lookup(mm, addr: start);
912 if (!vma)
913 return -ENOMEM;
914 }
915
916 tmp_end = min_t(unsigned long, end, vma->vm_end);
917 /* Populate (prefault) page tables readable/writable. */
918 pages = faultin_vma_page_range(vma, start, end: tmp_end, write,
919 locked: &locked);
920 if (!locked) {
921 mmap_read_lock(mm);
922 locked = 1;
923 *prev = NULL;
924 vma = NULL;
925 }
926 if (pages < 0) {
927 switch (pages) {
928 case -EINTR:
929 return -EINTR;
930 case -EINVAL: /* Incompatible mappings / permissions. */
931 return -EINVAL;
932 case -EHWPOISON:
933 return -EHWPOISON;
934 case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
935 return -EFAULT;
936 default:
937 pr_warn_once("%s: unhandled return value: %ld\n",
938 __func__, pages);
939 fallthrough;
940 case -ENOMEM:
941 return -ENOMEM;
942 }
943 }
944 start += pages * PAGE_SIZE;
945 }
946 return 0;
947}
948
949/*
950 * Application wants to free up the pages and associated backing store.
951 * This is effectively punching a hole into the middle of a file.
952 */
953static long madvise_remove(struct vm_area_struct *vma,
954 struct vm_area_struct **prev,
955 unsigned long start, unsigned long end)
956{
957 loff_t offset;
958 int error;
959 struct file *f;
960 struct mm_struct *mm = vma->vm_mm;
961
962 *prev = NULL; /* tell sys_madvise we drop mmap_lock */
963
964 if (vma->vm_flags & VM_LOCKED)
965 return -EINVAL;
966
967 f = vma->vm_file;
968
969 if (!f || !f->f_mapping || !f->f_mapping->host) {
970 return -EINVAL;
971 }
972
973 if (!vma_is_shared_maywrite(vma))
974 return -EACCES;
975
976 offset = (loff_t)(start - vma->vm_start)
977 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
978
979 /*
980 * Filesystem's fallocate may need to take i_rwsem. We need to
981 * explicitly grab a reference because the vma (and hence the
982 * vma's reference to the file) can go away as soon as we drop
983 * mmap_lock.
984 */
985 get_file(f);
986 if (userfaultfd_remove(vma, start, end)) {
987 /* mmap_lock was not released by userfaultfd_remove() */
988 mmap_read_unlock(mm);
989 }
990 error = vfs_fallocate(file: f,
991 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
992 offset, len: end - start);
993 fput(f);
994 mmap_read_lock(mm);
995 return error;
996}
997
998/*
999 * Apply an madvise behavior to a region of a vma. madvise_update_vma
1000 * will handle splitting a vm area into separate areas, each area with its own
1001 * behavior.
1002 */
1003static int madvise_vma_behavior(struct vm_area_struct *vma,
1004 struct vm_area_struct **prev,
1005 unsigned long start, unsigned long end,
1006 unsigned long behavior)
1007{
1008 int error;
1009 struct anon_vma_name *anon_name;
1010 unsigned long new_flags = vma->vm_flags;
1011
1012 switch (behavior) {
1013 case MADV_REMOVE:
1014 return madvise_remove(vma, prev, start, end);
1015 case MADV_WILLNEED:
1016 return madvise_willneed(vma, prev, start, end);
1017 case MADV_COLD:
1018 return madvise_cold(vma, prev, start_addr: start, end_addr: end);
1019 case MADV_PAGEOUT:
1020 return madvise_pageout(vma, prev, start_addr: start, end_addr: end);
1021 case MADV_FREE:
1022 case MADV_DONTNEED:
1023 case MADV_DONTNEED_LOCKED:
1024 return madvise_dontneed_free(vma, prev, start, end, behavior);
1025 case MADV_POPULATE_READ:
1026 case MADV_POPULATE_WRITE:
1027 return madvise_populate(vma, prev, start, end, behavior);
1028 case MADV_NORMAL:
1029 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
1030 break;
1031 case MADV_SEQUENTIAL:
1032 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
1033 break;
1034 case MADV_RANDOM:
1035 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
1036 break;
1037 case MADV_DONTFORK:
1038 new_flags |= VM_DONTCOPY;
1039 break;
1040 case MADV_DOFORK:
1041 if (vma->vm_flags & VM_IO)
1042 return -EINVAL;
1043 new_flags &= ~VM_DONTCOPY;
1044 break;
1045 case MADV_WIPEONFORK:
1046 /* MADV_WIPEONFORK is only supported on anonymous memory. */
1047 if (vma->vm_file || vma->vm_flags & VM_SHARED)
1048 return -EINVAL;
1049 new_flags |= VM_WIPEONFORK;
1050 break;
1051 case MADV_KEEPONFORK:
1052 new_flags &= ~VM_WIPEONFORK;
1053 break;
1054 case MADV_DONTDUMP:
1055 new_flags |= VM_DONTDUMP;
1056 break;
1057 case MADV_DODUMP:
1058 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
1059 return -EINVAL;
1060 new_flags &= ~VM_DONTDUMP;
1061 break;
1062 case MADV_MERGEABLE:
1063 case MADV_UNMERGEABLE:
1064 error = ksm_madvise(vma, start, end, advice: behavior, vm_flags: &new_flags);
1065 if (error)
1066 goto out;
1067 break;
1068 case MADV_HUGEPAGE:
1069 case MADV_NOHUGEPAGE:
1070 error = hugepage_madvise(vma, vm_flags: &new_flags, advice: behavior);
1071 if (error)
1072 goto out;
1073 break;
1074 case MADV_COLLAPSE:
1075 return madvise_collapse(vma, prev, start, end);
1076 }
1077
1078 anon_name = anon_vma_name(vma);
1079 anon_vma_name_get(anon_name);
1080 error = madvise_update_vma(vma, prev, start, end, new_flags,
1081 anon_name);
1082 anon_vma_name_put(anon_name);
1083
1084out:
1085 /*
1086 * madvise() returns EAGAIN if kernel resources, such as
1087 * slab, are temporarily unavailable.
1088 */
1089 if (error == -ENOMEM)
1090 error = -EAGAIN;
1091 return error;
1092}
1093
1094#ifdef CONFIG_MEMORY_FAILURE
1095/*
1096 * Error injection support for memory error handling.
1097 */
1098static int madvise_inject_error(int behavior,
1099 unsigned long start, unsigned long end)
1100{
1101 unsigned long size;
1102
1103 if (!capable(CAP_SYS_ADMIN))
1104 return -EPERM;
1105
1106
1107 for (; start < end; start += size) {
1108 unsigned long pfn;
1109 struct page *page;
1110 int ret;
1111
1112 ret = get_user_pages_fast(start, nr_pages: 1, gup_flags: 0, pages: &page);
1113 if (ret != 1)
1114 return ret;
1115 pfn = page_to_pfn(page);
1116
1117 /*
1118 * When soft offlining hugepages, after migrating the page
1119 * we dissolve it, therefore in the second loop "page" will
1120 * no longer be a compound page.
1121 */
1122 size = page_size(compound_head(page));
1123
1124 if (behavior == MADV_SOFT_OFFLINE) {
1125 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1126 pfn, start);
1127 ret = soft_offline_page(pfn, flags: MF_COUNT_INCREASED);
1128 } else {
1129 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1130 pfn, start);
1131 ret = memory_failure(pfn, flags: MF_COUNT_INCREASED | MF_SW_SIMULATED);
1132 if (ret == -EOPNOTSUPP)
1133 ret = 0;
1134 }
1135
1136 if (ret)
1137 return ret;
1138 }
1139
1140 return 0;
1141}
1142#endif
1143
1144static bool
1145madvise_behavior_valid(int behavior)
1146{
1147 switch (behavior) {
1148 case MADV_DOFORK:
1149 case MADV_DONTFORK:
1150 case MADV_NORMAL:
1151 case MADV_SEQUENTIAL:
1152 case MADV_RANDOM:
1153 case MADV_REMOVE:
1154 case MADV_WILLNEED:
1155 case MADV_DONTNEED:
1156 case MADV_DONTNEED_LOCKED:
1157 case MADV_FREE:
1158 case MADV_COLD:
1159 case MADV_PAGEOUT:
1160 case MADV_POPULATE_READ:
1161 case MADV_POPULATE_WRITE:
1162#ifdef CONFIG_KSM
1163 case MADV_MERGEABLE:
1164 case MADV_UNMERGEABLE:
1165#endif
1166#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1167 case MADV_HUGEPAGE:
1168 case MADV_NOHUGEPAGE:
1169 case MADV_COLLAPSE:
1170#endif
1171 case MADV_DONTDUMP:
1172 case MADV_DODUMP:
1173 case MADV_WIPEONFORK:
1174 case MADV_KEEPONFORK:
1175#ifdef CONFIG_MEMORY_FAILURE
1176 case MADV_SOFT_OFFLINE:
1177 case MADV_HWPOISON:
1178#endif
1179 return true;
1180
1181 default:
1182 return false;
1183 }
1184}
1185
1186static bool process_madvise_behavior_valid(int behavior)
1187{
1188 switch (behavior) {
1189 case MADV_COLD:
1190 case MADV_PAGEOUT:
1191 case MADV_WILLNEED:
1192 case MADV_COLLAPSE:
1193 return true;
1194 default:
1195 return false;
1196 }
1197}
1198
1199/*
1200 * Walk the vmas in range [start,end), and call the visit function on each one.
1201 * The visit function will get start and end parameters that cover the overlap
1202 * between the current vma and the original range. Any unmapped regions in the
1203 * original range will result in this function returning -ENOMEM while still
1204 * calling the visit function on all of the existing vmas in the range.
1205 * Must be called with the mmap_lock held for reading or writing.
1206 */
1207static
1208int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
1209 unsigned long end, unsigned long arg,
1210 int (*visit)(struct vm_area_struct *vma,
1211 struct vm_area_struct **prev, unsigned long start,
1212 unsigned long end, unsigned long arg))
1213{
1214 struct vm_area_struct *vma;
1215 struct vm_area_struct *prev;
1216 unsigned long tmp;
1217 int unmapped_error = 0;
1218
1219 /*
1220 * If the interval [start,end) covers some unmapped address
1221 * ranges, just ignore them, but return -ENOMEM at the end.
1222 * - different from the way of handling in mlock etc.
1223 */
1224 vma = find_vma_prev(mm, addr: start, pprev: &prev);
1225 if (vma && start > vma->vm_start)
1226 prev = vma;
1227
1228 for (;;) {
1229 int error;
1230
1231 /* Still start < end. */
1232 if (!vma)
1233 return -ENOMEM;
1234
1235 /* Here start < (end|vma->vm_end). */
1236 if (start < vma->vm_start) {
1237 unmapped_error = -ENOMEM;
1238 start = vma->vm_start;
1239 if (start >= end)
1240 break;
1241 }
1242
1243 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1244 tmp = vma->vm_end;
1245 if (end < tmp)
1246 tmp = end;
1247
1248 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1249 error = visit(vma, &prev, start, tmp, arg);
1250 if (error)
1251 return error;
1252 start = tmp;
1253 if (prev && start < prev->vm_end)
1254 start = prev->vm_end;
1255 if (start >= end)
1256 break;
1257 if (prev)
1258 vma = find_vma(mm, addr: prev->vm_end);
1259 else /* madvise_remove dropped mmap_lock */
1260 vma = find_vma(mm, addr: start);
1261 }
1262
1263 return unmapped_error;
1264}
1265
1266#ifdef CONFIG_ANON_VMA_NAME
1267static int madvise_vma_anon_name(struct vm_area_struct *vma,
1268 struct vm_area_struct **prev,
1269 unsigned long start, unsigned long end,
1270 unsigned long anon_name)
1271{
1272 int error;
1273
1274 /* Only anonymous mappings can be named */
1275 if (vma->vm_file && !vma_is_anon_shmem(vma))
1276 return -EBADF;
1277
1278 error = madvise_update_vma(vma, prev, start, end, new_flags: vma->vm_flags,
1279 anon_name: (struct anon_vma_name *)anon_name);
1280
1281 /*
1282 * madvise() returns EAGAIN if kernel resources, such as
1283 * slab, are temporarily unavailable.
1284 */
1285 if (error == -ENOMEM)
1286 error = -EAGAIN;
1287 return error;
1288}
1289
1290int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
1291 unsigned long len_in, struct anon_vma_name *anon_name)
1292{
1293 unsigned long end;
1294 unsigned long len;
1295
1296 if (start & ~PAGE_MASK)
1297 return -EINVAL;
1298 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1299
1300 /* Check to see whether len was rounded up from small -ve to zero */
1301 if (len_in && !len)
1302 return -EINVAL;
1303
1304 end = start + len;
1305 if (end < start)
1306 return -EINVAL;
1307
1308 if (end == start)
1309 return 0;
1310
1311 return madvise_walk_vmas(mm, start, end, arg: (unsigned long)anon_name,
1312 visit: madvise_vma_anon_name);
1313}
1314#endif /* CONFIG_ANON_VMA_NAME */
1315/*
1316 * The madvise(2) system call.
1317 *
1318 * Applications can use madvise() to advise the kernel how it should
1319 * handle paging I/O in this VM area. The idea is to help the kernel
1320 * use appropriate read-ahead and caching techniques. The information
1321 * provided is advisory only, and can be safely disregarded by the
1322 * kernel without affecting the correct operation of the application.
1323 *
1324 * behavior values:
1325 * MADV_NORMAL - the default behavior is to read clusters. This
1326 * results in some read-ahead and read-behind.
1327 * MADV_RANDOM - the system should read the minimum amount of data
1328 * on any access, since it is unlikely that the appli-
1329 * cation will need more than what it asks for.
1330 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
1331 * once, so they can be aggressively read ahead, and
1332 * can be freed soon after they are accessed.
1333 * MADV_WILLNEED - the application is notifying the system to read
1334 * some pages ahead.
1335 * MADV_DONTNEED - the application is finished with the given range,
1336 * so the kernel can free resources associated with it.
1337 * MADV_FREE - the application marks pages in the given range as lazy free,
1338 * where actual purges are postponed until memory pressure happens.
1339 * MADV_REMOVE - the application wants to free up the given range of
1340 * pages and associated backing store.
1341 * MADV_DONTFORK - omit this area from child's address space when forking:
1342 * typically, to avoid COWing pages pinned by get_user_pages().
1343 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1344 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
1345 * range after a fork.
1346 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1347 * MADV_HWPOISON - trigger memory error handler as if the given memory range
1348 * were corrupted by unrecoverable hardware memory failure.
1349 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1350 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1351 * this area with pages of identical content from other such areas.
1352 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1353 * MADV_HUGEPAGE - the application wants to back the given range by transparent
1354 * huge pages in the future. Existing pages might be coalesced and
1355 * new pages might be allocated as THP.
1356 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1357 * transparent huge pages so the existing pages will not be
1358 * coalesced into THP and new pages will not be allocated as THP.
1359 * MADV_COLLAPSE - synchronously coalesce pages into new THP.
1360 * MADV_DONTDUMP - the application wants to prevent pages in the given range
1361 * from being included in its core dump.
1362 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1363 * MADV_COLD - the application is not expected to use this memory soon,
1364 * deactivate pages in this range so that they can be reclaimed
1365 * easily if memory pressure happens.
1366 * MADV_PAGEOUT - the application is not expected to use this memory soon,
1367 * page out the pages in this range immediately.
1368 * MADV_POPULATE_READ - populate (prefault) page tables readable by
1369 * triggering read faults if required
1370 * MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1371 * triggering write faults if required
1372 *
1373 * return values:
1374 * zero - success
1375 * -EINVAL - start + len < 0, start is not page-aligned,
1376 * "behavior" is not a valid value, or application
1377 * is attempting to release locked or shared pages,
1378 * or the specified address range includes file, Huge TLB,
1379 * MAP_SHARED or VMPFNMAP range.
1380 * -ENOMEM - addresses in the specified range are not currently
1381 * mapped, or are outside the AS of the process.
1382 * -EIO - an I/O error occurred while paging in data.
1383 * -EBADF - map exists, but area maps something that isn't a file.
1384 * -EAGAIN - a kernel resource was temporarily unavailable.
1385 */
1386int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1387{
1388 unsigned long end;
1389 int error;
1390 int write;
1391 size_t len;
1392 struct blk_plug plug;
1393
1394 if (!madvise_behavior_valid(behavior))
1395 return -EINVAL;
1396
1397 if (!PAGE_ALIGNED(start))
1398 return -EINVAL;
1399 len = PAGE_ALIGN(len_in);
1400
1401 /* Check to see whether len was rounded up from small -ve to zero */
1402 if (len_in && !len)
1403 return -EINVAL;
1404
1405 end = start + len;
1406 if (end < start)
1407 return -EINVAL;
1408
1409 if (end == start)
1410 return 0;
1411
1412#ifdef CONFIG_MEMORY_FAILURE
1413 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1414 return madvise_inject_error(behavior, start, end: start + len_in);
1415#endif
1416
1417 write = madvise_need_mmap_write(behavior);
1418 if (write) {
1419 if (mmap_write_lock_killable(mm))
1420 return -EINTR;
1421 } else {
1422 mmap_read_lock(mm);
1423 }
1424
1425 start = untagged_addr_remote(mm, start);
1426 end = start + len;
1427
1428 blk_start_plug(&plug);
1429 error = madvise_walk_vmas(mm, start, end, arg: behavior,
1430 visit: madvise_vma_behavior);
1431 blk_finish_plug(&plug);
1432 if (write)
1433 mmap_write_unlock(mm);
1434 else
1435 mmap_read_unlock(mm);
1436
1437 return error;
1438}
1439
1440SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1441{
1442 return do_madvise(current->mm, start, len_in, behavior);
1443}
1444
1445SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1446 size_t, vlen, int, behavior, unsigned int, flags)
1447{
1448 ssize_t ret;
1449 struct iovec iovstack[UIO_FASTIOV];
1450 struct iovec *iov = iovstack;
1451 struct iov_iter iter;
1452 struct task_struct *task;
1453 struct mm_struct *mm;
1454 size_t total_len;
1455 unsigned int f_flags;
1456
1457 if (flags != 0) {
1458 ret = -EINVAL;
1459 goto out;
1460 }
1461
1462 ret = import_iovec(ITER_DEST, uvec: vec, nr_segs: vlen, ARRAY_SIZE(iovstack), iovp: &iov, i: &iter);
1463 if (ret < 0)
1464 goto out;
1465
1466 task = pidfd_get_task(pidfd, flags: &f_flags);
1467 if (IS_ERR(ptr: task)) {
1468 ret = PTR_ERR(ptr: task);
1469 goto free_iov;
1470 }
1471
1472 if (!process_madvise_behavior_valid(behavior)) {
1473 ret = -EINVAL;
1474 goto release_task;
1475 }
1476
1477 /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1478 mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1479 if (IS_ERR_OR_NULL(ptr: mm)) {
1480 ret = IS_ERR(ptr: mm) ? PTR_ERR(ptr: mm) : -ESRCH;
1481 goto release_task;
1482 }
1483
1484 /*
1485 * Require CAP_SYS_NICE for influencing process performance. Note that
1486 * only non-destructive hints are currently supported.
1487 */
1488 if (!capable(CAP_SYS_NICE)) {
1489 ret = -EPERM;
1490 goto release_mm;
1491 }
1492
1493 total_len = iov_iter_count(i: &iter);
1494
1495 while (iov_iter_count(i: &iter)) {
1496 ret = do_madvise(mm, start: (unsigned long)iter_iov_addr(&iter),
1497 iter_iov_len(&iter), behavior);
1498 if (ret < 0)
1499 break;
1500 iov_iter_advance(i: &iter, iter_iov_len(&iter));
1501 }
1502
1503 ret = (total_len - iov_iter_count(i: &iter)) ? : ret;
1504
1505release_mm:
1506 mmput(mm);
1507release_task:
1508 put_task_struct(t: task);
1509free_iov:
1510 kfree(objp: iov);
1511out:
1512 return ret;
1513}
1514

source code of linux/mm/madvise.c