Merge tag 'block-5.14-2021-08-20' of git://git.kernel.dk/linux-block
[linux-2.6-microblaze.git] / mm / madvise.c
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/uio.h>
22 #include <linux/ksm.h>
23 #include <linux/fs.h>
24 #include <linux/file.h>
25 #include <linux/blkdev.h>
26 #include <linux/backing-dev.h>
27 #include <linux/pagewalk.h>
28 #include <linux/swap.h>
29 #include <linux/swapops.h>
30 #include <linux/shmem_fs.h>
31 #include <linux/mmu_notifier.h>
32
33 #include <asm/tlb.h>
34
35 #include "internal.h"
36
37 struct madvise_walk_private {
38         struct mmu_gather *tlb;
39         bool pageout;
40 };
41
42 /*
43  * Any behaviour which results in changes to the vma->vm_flags needs to
44  * take mmap_lock for writing. Others, which simply traverse vmas, need
45  * to only take it for reading.
46  */
47 static int madvise_need_mmap_write(int behavior)
48 {
49         switch (behavior) {
50         case MADV_REMOVE:
51         case MADV_WILLNEED:
52         case MADV_DONTNEED:
53         case MADV_COLD:
54         case MADV_PAGEOUT:
55         case MADV_FREE:
56         case MADV_POPULATE_READ:
57         case MADV_POPULATE_WRITE:
58                 return 0;
59         default:
60                 /* be safe, default to 1. list exceptions explicitly */
61                 return 1;
62         }
63 }
64
65 /*
66  * We can potentially split a vm area into separate
67  * areas, each area with its own behavior.
68  */
69 static long madvise_behavior(struct vm_area_struct *vma,
70                      struct vm_area_struct **prev,
71                      unsigned long start, unsigned long end, int behavior)
72 {
73         struct mm_struct *mm = vma->vm_mm;
74         int error = 0;
75         pgoff_t pgoff;
76         unsigned long new_flags = vma->vm_flags;
77
78         switch (behavior) {
79         case MADV_NORMAL:
80                 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
81                 break;
82         case MADV_SEQUENTIAL:
83                 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
84                 break;
85         case MADV_RANDOM:
86                 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
87                 break;
88         case MADV_DONTFORK:
89                 new_flags |= VM_DONTCOPY;
90                 break;
91         case MADV_DOFORK:
92                 if (vma->vm_flags & VM_IO) {
93                         error = -EINVAL;
94                         goto out;
95                 }
96                 new_flags &= ~VM_DONTCOPY;
97                 break;
98         case MADV_WIPEONFORK:
99                 /* MADV_WIPEONFORK is only supported on anonymous memory. */
100                 if (vma->vm_file || vma->vm_flags & VM_SHARED) {
101                         error = -EINVAL;
102                         goto out;
103                 }
104                 new_flags |= VM_WIPEONFORK;
105                 break;
106         case MADV_KEEPONFORK:
107                 new_flags &= ~VM_WIPEONFORK;
108                 break;
109         case MADV_DONTDUMP:
110                 new_flags |= VM_DONTDUMP;
111                 break;
112         case MADV_DODUMP:
113                 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) {
114                         error = -EINVAL;
115                         goto out;
116                 }
117                 new_flags &= ~VM_DONTDUMP;
118                 break;
119         case MADV_MERGEABLE:
120         case MADV_UNMERGEABLE:
121                 error = ksm_madvise(vma, start, end, behavior, &new_flags);
122                 if (error)
123                         goto out_convert_errno;
124                 break;
125         case MADV_HUGEPAGE:
126         case MADV_NOHUGEPAGE:
127                 error = hugepage_madvise(vma, &new_flags, behavior);
128                 if (error)
129                         goto out_convert_errno;
130                 break;
131         }
132
133         if (new_flags == vma->vm_flags) {
134                 *prev = vma;
135                 goto out;
136         }
137
138         pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
139         *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
140                           vma->vm_file, pgoff, vma_policy(vma),
141                           vma->vm_userfaultfd_ctx);
142         if (*prev) {
143                 vma = *prev;
144                 goto success;
145         }
146
147         *prev = vma;
148
149         if (start != vma->vm_start) {
150                 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
151                         error = -ENOMEM;
152                         goto out;
153                 }
154                 error = __split_vma(mm, vma, start, 1);
155                 if (error)
156                         goto out_convert_errno;
157         }
158
159         if (end != vma->vm_end) {
160                 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
161                         error = -ENOMEM;
162                         goto out;
163                 }
164                 error = __split_vma(mm, vma, end, 0);
165                 if (error)
166                         goto out_convert_errno;
167         }
168
169 success:
170         /*
171          * vm_flags is protected by the mmap_lock held in write mode.
172          */
173         vma->vm_flags = new_flags;
174
175 out_convert_errno:
176         /*
177          * madvise() returns EAGAIN if kernel resources, such as
178          * slab, are temporarily unavailable.
179          */
180         if (error == -ENOMEM)
181                 error = -EAGAIN;
182 out:
183         return error;
184 }
185
186 #ifdef CONFIG_SWAP
187 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
188         unsigned long end, struct mm_walk *walk)
189 {
190         pte_t *orig_pte;
191         struct vm_area_struct *vma = walk->private;
192         unsigned long index;
193
194         if (pmd_none_or_trans_huge_or_clear_bad(pmd))
195                 return 0;
196
197         for (index = start; index != end; index += PAGE_SIZE) {
198                 pte_t pte;
199                 swp_entry_t entry;
200                 struct page *page;
201                 spinlock_t *ptl;
202
203                 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
204                 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
205                 pte_unmap_unlock(orig_pte, ptl);
206
207                 if (pte_present(pte) || pte_none(pte))
208                         continue;
209                 entry = pte_to_swp_entry(pte);
210                 if (unlikely(non_swap_entry(entry)))
211                         continue;
212
213                 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
214                                                         vma, index, false);
215                 if (page)
216                         put_page(page);
217         }
218
219         return 0;
220 }
221
222 static const struct mm_walk_ops swapin_walk_ops = {
223         .pmd_entry              = swapin_walk_pmd_entry,
224 };
225
226 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
227                 unsigned long start, unsigned long end,
228                 struct address_space *mapping)
229 {
230         XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
231         pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
232         struct page *page;
233
234         rcu_read_lock();
235         xas_for_each(&xas, page, end_index) {
236                 swp_entry_t swap;
237
238                 if (!xa_is_value(page))
239                         continue;
240                 xas_pause(&xas);
241                 rcu_read_unlock();
242
243                 swap = radix_to_swp_entry(page);
244                 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
245                                                         NULL, 0, false);
246                 if (page)
247                         put_page(page);
248
249                 rcu_read_lock();
250         }
251         rcu_read_unlock();
252
253         lru_add_drain();        /* Push any new pages onto the LRU now */
254 }
255 #endif          /* CONFIG_SWAP */
256
257 /*
258  * Schedule all required I/O operations.  Do not wait for completion.
259  */
260 static long madvise_willneed(struct vm_area_struct *vma,
261                              struct vm_area_struct **prev,
262                              unsigned long start, unsigned long end)
263 {
264         struct mm_struct *mm = vma->vm_mm;
265         struct file *file = vma->vm_file;
266         loff_t offset;
267
268         *prev = vma;
269 #ifdef CONFIG_SWAP
270         if (!file) {
271                 walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
272                 lru_add_drain(); /* Push any new pages onto the LRU now */
273                 return 0;
274         }
275
276         if (shmem_mapping(file->f_mapping)) {
277                 force_shm_swapin_readahead(vma, start, end,
278                                         file->f_mapping);
279                 return 0;
280         }
281 #else
282         if (!file)
283                 return -EBADF;
284 #endif
285
286         if (IS_DAX(file_inode(file))) {
287                 /* no bad return value, but ignore advice */
288                 return 0;
289         }
290
291         /*
292          * Filesystem's fadvise may need to take various locks.  We need to
293          * explicitly grab a reference because the vma (and hence the
294          * vma's reference to the file) can go away as soon as we drop
295          * mmap_lock.
296          */
297         *prev = NULL;   /* tell sys_madvise we drop mmap_lock */
298         get_file(file);
299         offset = (loff_t)(start - vma->vm_start)
300                         + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
301         mmap_read_unlock(mm);
302         vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
303         fput(file);
304         mmap_read_lock(mm);
305         return 0;
306 }
307
308 static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
309                                 unsigned long addr, unsigned long end,
310                                 struct mm_walk *walk)
311 {
312         struct madvise_walk_private *private = walk->private;
313         struct mmu_gather *tlb = private->tlb;
314         bool pageout = private->pageout;
315         struct mm_struct *mm = tlb->mm;
316         struct vm_area_struct *vma = walk->vma;
317         pte_t *orig_pte, *pte, ptent;
318         spinlock_t *ptl;
319         struct page *page = NULL;
320         LIST_HEAD(page_list);
321
322         if (fatal_signal_pending(current))
323                 return -EINTR;
324
325 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
326         if (pmd_trans_huge(*pmd)) {
327                 pmd_t orig_pmd;
328                 unsigned long next = pmd_addr_end(addr, end);
329
330                 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
331                 ptl = pmd_trans_huge_lock(pmd, vma);
332                 if (!ptl)
333                         return 0;
334
335                 orig_pmd = *pmd;
336                 if (is_huge_zero_pmd(orig_pmd))
337                         goto huge_unlock;
338
339                 if (unlikely(!pmd_present(orig_pmd))) {
340                         VM_BUG_ON(thp_migration_supported() &&
341                                         !is_pmd_migration_entry(orig_pmd));
342                         goto huge_unlock;
343                 }
344
345                 page = pmd_page(orig_pmd);
346
347                 /* Do not interfere with other mappings of this page */
348                 if (page_mapcount(page) != 1)
349                         goto huge_unlock;
350
351                 if (next - addr != HPAGE_PMD_SIZE) {
352                         int err;
353
354                         get_page(page);
355                         spin_unlock(ptl);
356                         lock_page(page);
357                         err = split_huge_page(page);
358                         unlock_page(page);
359                         put_page(page);
360                         if (!err)
361                                 goto regular_page;
362                         return 0;
363                 }
364
365                 if (pmd_young(orig_pmd)) {
366                         pmdp_invalidate(vma, addr, pmd);
367                         orig_pmd = pmd_mkold(orig_pmd);
368
369                         set_pmd_at(mm, addr, pmd, orig_pmd);
370                         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
371                 }
372
373                 ClearPageReferenced(page);
374                 test_and_clear_page_young(page);
375                 if (pageout) {
376                         if (!isolate_lru_page(page)) {
377                                 if (PageUnevictable(page))
378                                         putback_lru_page(page);
379                                 else
380                                         list_add(&page->lru, &page_list);
381                         }
382                 } else
383                         deactivate_page(page);
384 huge_unlock:
385                 spin_unlock(ptl);
386                 if (pageout)
387                         reclaim_pages(&page_list);
388                 return 0;
389         }
390
391 regular_page:
392         if (pmd_trans_unstable(pmd))
393                 return 0;
394 #endif
395         tlb_change_page_size(tlb, PAGE_SIZE);
396         orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
397         flush_tlb_batched_pending(mm);
398         arch_enter_lazy_mmu_mode();
399         for (; addr < end; pte++, addr += PAGE_SIZE) {
400                 ptent = *pte;
401
402                 if (pte_none(ptent))
403                         continue;
404
405                 if (!pte_present(ptent))
406                         continue;
407
408                 page = vm_normal_page(vma, addr, ptent);
409                 if (!page)
410                         continue;
411
412                 /*
413                  * Creating a THP page is expensive so split it only if we
414                  * are sure it's worth. Split it if we are only owner.
415                  */
416                 if (PageTransCompound(page)) {
417                         if (page_mapcount(page) != 1)
418                                 break;
419                         get_page(page);
420                         if (!trylock_page(page)) {
421                                 put_page(page);
422                                 break;
423                         }
424                         pte_unmap_unlock(orig_pte, ptl);
425                         if (split_huge_page(page)) {
426                                 unlock_page(page);
427                                 put_page(page);
428                                 pte_offset_map_lock(mm, pmd, addr, &ptl);
429                                 break;
430                         }
431                         unlock_page(page);
432                         put_page(page);
433                         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
434                         pte--;
435                         addr -= PAGE_SIZE;
436                         continue;
437                 }
438
439                 /* Do not interfere with other mappings of this page */
440                 if (page_mapcount(page) != 1)
441                         continue;
442
443                 VM_BUG_ON_PAGE(PageTransCompound(page), page);
444
445                 if (pte_young(ptent)) {
446                         ptent = ptep_get_and_clear_full(mm, addr, pte,
447                                                         tlb->fullmm);
448                         ptent = pte_mkold(ptent);
449                         set_pte_at(mm, addr, pte, ptent);
450                         tlb_remove_tlb_entry(tlb, pte, addr);
451                 }
452
453                 /*
454                  * We are deactivating a page for accelerating reclaiming.
455                  * VM couldn't reclaim the page unless we clear PG_young.
456                  * As a side effect, it makes confuse idle-page tracking
457                  * because they will miss recent referenced history.
458                  */
459                 ClearPageReferenced(page);
460                 test_and_clear_page_young(page);
461                 if (pageout) {
462                         if (!isolate_lru_page(page)) {
463                                 if (PageUnevictable(page))
464                                         putback_lru_page(page);
465                                 else
466                                         list_add(&page->lru, &page_list);
467                         }
468                 } else
469                         deactivate_page(page);
470         }
471
472         arch_leave_lazy_mmu_mode();
473         pte_unmap_unlock(orig_pte, ptl);
474         if (pageout)
475                 reclaim_pages(&page_list);
476         cond_resched();
477
478         return 0;
479 }
480
481 static const struct mm_walk_ops cold_walk_ops = {
482         .pmd_entry = madvise_cold_or_pageout_pte_range,
483 };
484
485 static void madvise_cold_page_range(struct mmu_gather *tlb,
486                              struct vm_area_struct *vma,
487                              unsigned long addr, unsigned long end)
488 {
489         struct madvise_walk_private walk_private = {
490                 .pageout = false,
491                 .tlb = tlb,
492         };
493
494         tlb_start_vma(tlb, vma);
495         walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
496         tlb_end_vma(tlb, vma);
497 }
498
499 static long madvise_cold(struct vm_area_struct *vma,
500                         struct vm_area_struct **prev,
501                         unsigned long start_addr, unsigned long end_addr)
502 {
503         struct mm_struct *mm = vma->vm_mm;
504         struct mmu_gather tlb;
505
506         *prev = vma;
507         if (!can_madv_lru_vma(vma))
508                 return -EINVAL;
509
510         lru_add_drain();
511         tlb_gather_mmu(&tlb, mm);
512         madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
513         tlb_finish_mmu(&tlb);
514
515         return 0;
516 }
517
518 static void madvise_pageout_page_range(struct mmu_gather *tlb,
519                              struct vm_area_struct *vma,
520                              unsigned long addr, unsigned long end)
521 {
522         struct madvise_walk_private walk_private = {
523                 .pageout = true,
524                 .tlb = tlb,
525         };
526
527         tlb_start_vma(tlb, vma);
528         walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
529         tlb_end_vma(tlb, vma);
530 }
531
532 static inline bool can_do_pageout(struct vm_area_struct *vma)
533 {
534         if (vma_is_anonymous(vma))
535                 return true;
536         if (!vma->vm_file)
537                 return false;
538         /*
539          * paging out pagecache only for non-anonymous mappings that correspond
540          * to the files the calling process could (if tried) open for writing;
541          * otherwise we'd be including shared non-exclusive mappings, which
542          * opens a side channel.
543          */
544         return inode_owner_or_capable(&init_user_ns,
545                                       file_inode(vma->vm_file)) ||
546                file_permission(vma->vm_file, MAY_WRITE) == 0;
547 }
548
549 static long madvise_pageout(struct vm_area_struct *vma,
550                         struct vm_area_struct **prev,
551                         unsigned long start_addr, unsigned long end_addr)
552 {
553         struct mm_struct *mm = vma->vm_mm;
554         struct mmu_gather tlb;
555
556         *prev = vma;
557         if (!can_madv_lru_vma(vma))
558                 return -EINVAL;
559
560         if (!can_do_pageout(vma))
561                 return 0;
562
563         lru_add_drain();
564         tlb_gather_mmu(&tlb, mm);
565         madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
566         tlb_finish_mmu(&tlb);
567
568         return 0;
569 }
570
571 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
572                                 unsigned long end, struct mm_walk *walk)
573
574 {
575         struct mmu_gather *tlb = walk->private;
576         struct mm_struct *mm = tlb->mm;
577         struct vm_area_struct *vma = walk->vma;
578         spinlock_t *ptl;
579         pte_t *orig_pte, *pte, ptent;
580         struct page *page;
581         int nr_swap = 0;
582         unsigned long next;
583
584         next = pmd_addr_end(addr, end);
585         if (pmd_trans_huge(*pmd))
586                 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
587                         goto next;
588
589         if (pmd_trans_unstable(pmd))
590                 return 0;
591
592         tlb_change_page_size(tlb, PAGE_SIZE);
593         orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
594         flush_tlb_batched_pending(mm);
595         arch_enter_lazy_mmu_mode();
596         for (; addr != end; pte++, addr += PAGE_SIZE) {
597                 ptent = *pte;
598
599                 if (pte_none(ptent))
600                         continue;
601                 /*
602                  * If the pte has swp_entry, just clear page table to
603                  * prevent swap-in which is more expensive rather than
604                  * (page allocation + zeroing).
605                  */
606                 if (!pte_present(ptent)) {
607                         swp_entry_t entry;
608
609                         entry = pte_to_swp_entry(ptent);
610                         if (non_swap_entry(entry))
611                                 continue;
612                         nr_swap--;
613                         free_swap_and_cache(entry);
614                         pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
615                         continue;
616                 }
617
618                 page = vm_normal_page(vma, addr, ptent);
619                 if (!page)
620                         continue;
621
622                 /*
623                  * If pmd isn't transhuge but the page is THP and
624                  * is owned by only this process, split it and
625                  * deactivate all pages.
626                  */
627                 if (PageTransCompound(page)) {
628                         if (page_mapcount(page) != 1)
629                                 goto out;
630                         get_page(page);
631                         if (!trylock_page(page)) {
632                                 put_page(page);
633                                 goto out;
634                         }
635                         pte_unmap_unlock(orig_pte, ptl);
636                         if (split_huge_page(page)) {
637                                 unlock_page(page);
638                                 put_page(page);
639                                 pte_offset_map_lock(mm, pmd, addr, &ptl);
640                                 goto out;
641                         }
642                         unlock_page(page);
643                         put_page(page);
644                         pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
645                         pte--;
646                         addr -= PAGE_SIZE;
647                         continue;
648                 }
649
650                 VM_BUG_ON_PAGE(PageTransCompound(page), page);
651
652                 if (PageSwapCache(page) || PageDirty(page)) {
653                         if (!trylock_page(page))
654                                 continue;
655                         /*
656                          * If page is shared with others, we couldn't clear
657                          * PG_dirty of the page.
658                          */
659                         if (page_mapcount(page) != 1) {
660                                 unlock_page(page);
661                                 continue;
662                         }
663
664                         if (PageSwapCache(page) && !try_to_free_swap(page)) {
665                                 unlock_page(page);
666                                 continue;
667                         }
668
669                         ClearPageDirty(page);
670                         unlock_page(page);
671                 }
672
673                 if (pte_young(ptent) || pte_dirty(ptent)) {
674                         /*
675                          * Some of architecture(ex, PPC) don't update TLB
676                          * with set_pte_at and tlb_remove_tlb_entry so for
677                          * the portability, remap the pte with old|clean
678                          * after pte clearing.
679                          */
680                         ptent = ptep_get_and_clear_full(mm, addr, pte,
681                                                         tlb->fullmm);
682
683                         ptent = pte_mkold(ptent);
684                         ptent = pte_mkclean(ptent);
685                         set_pte_at(mm, addr, pte, ptent);
686                         tlb_remove_tlb_entry(tlb, pte, addr);
687                 }
688                 mark_page_lazyfree(page);
689         }
690 out:
691         if (nr_swap) {
692                 if (current->mm == mm)
693                         sync_mm_rss(mm);
694
695                 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
696         }
697         arch_leave_lazy_mmu_mode();
698         pte_unmap_unlock(orig_pte, ptl);
699         cond_resched();
700 next:
701         return 0;
702 }
703
704 static const struct mm_walk_ops madvise_free_walk_ops = {
705         .pmd_entry              = madvise_free_pte_range,
706 };
707
708 static int madvise_free_single_vma(struct vm_area_struct *vma,
709                         unsigned long start_addr, unsigned long end_addr)
710 {
711         struct mm_struct *mm = vma->vm_mm;
712         struct mmu_notifier_range range;
713         struct mmu_gather tlb;
714
715         /* MADV_FREE works for only anon vma at the moment */
716         if (!vma_is_anonymous(vma))
717                 return -EINVAL;
718
719         range.start = max(vma->vm_start, start_addr);
720         if (range.start >= vma->vm_end)
721                 return -EINVAL;
722         range.end = min(vma->vm_end, end_addr);
723         if (range.end <= vma->vm_start)
724                 return -EINVAL;
725         mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
726                                 range.start, range.end);
727
728         lru_add_drain();
729         tlb_gather_mmu(&tlb, mm);
730         update_hiwater_rss(mm);
731
732         mmu_notifier_invalidate_range_start(&range);
733         tlb_start_vma(&tlb, vma);
734         walk_page_range(vma->vm_mm, range.start, range.end,
735                         &madvise_free_walk_ops, &tlb);
736         tlb_end_vma(&tlb, vma);
737         mmu_notifier_invalidate_range_end(&range);
738         tlb_finish_mmu(&tlb);
739
740         return 0;
741 }
742
743 /*
744  * Application no longer needs these pages.  If the pages are dirty,
745  * it's OK to just throw them away.  The app will be more careful about
746  * data it wants to keep.  Be sure to free swap resources too.  The
747  * zap_page_range call sets things up for shrink_active_list to actually free
748  * these pages later if no one else has touched them in the meantime,
749  * although we could add these pages to a global reuse list for
750  * shrink_active_list to pick up before reclaiming other pages.
751  *
752  * NB: This interface discards data rather than pushes it out to swap,
753  * as some implementations do.  This has performance implications for
754  * applications like large transactional databases which want to discard
755  * pages in anonymous maps after committing to backing store the data
756  * that was kept in them.  There is no reason to write this data out to
757  * the swap area if the application is discarding it.
758  *
759  * An interface that causes the system to free clean pages and flush
760  * dirty pages is already available as msync(MS_INVALIDATE).
761  */
762 static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
763                                         unsigned long start, unsigned long end)
764 {
765         zap_page_range(vma, start, end - start);
766         return 0;
767 }
768
769 static long madvise_dontneed_free(struct vm_area_struct *vma,
770                                   struct vm_area_struct **prev,
771                                   unsigned long start, unsigned long end,
772                                   int behavior)
773 {
774         struct mm_struct *mm = vma->vm_mm;
775
776         *prev = vma;
777         if (!can_madv_lru_vma(vma))
778                 return -EINVAL;
779
780         if (!userfaultfd_remove(vma, start, end)) {
781                 *prev = NULL; /* mmap_lock has been dropped, prev is stale */
782
783                 mmap_read_lock(mm);
784                 vma = find_vma(mm, start);
785                 if (!vma)
786                         return -ENOMEM;
787                 if (start < vma->vm_start) {
788                         /*
789                          * This "vma" under revalidation is the one
790                          * with the lowest vma->vm_start where start
791                          * is also < vma->vm_end. If start <
792                          * vma->vm_start it means an hole materialized
793                          * in the user address space within the
794                          * virtual range passed to MADV_DONTNEED
795                          * or MADV_FREE.
796                          */
797                         return -ENOMEM;
798                 }
799                 if (!can_madv_lru_vma(vma))
800                         return -EINVAL;
801                 if (end > vma->vm_end) {
802                         /*
803                          * Don't fail if end > vma->vm_end. If the old
804                          * vma was split while the mmap_lock was
805                          * released the effect of the concurrent
806                          * operation may not cause madvise() to
807                          * have an undefined result. There may be an
808                          * adjacent next vma that we'll walk
809                          * next. userfaultfd_remove() will generate an
810                          * UFFD_EVENT_REMOVE repetition on the
811                          * end-vma->vm_end range, but the manager can
812                          * handle a repetition fine.
813                          */
814                         end = vma->vm_end;
815                 }
816                 VM_WARN_ON(start >= end);
817         }
818
819         if (behavior == MADV_DONTNEED)
820                 return madvise_dontneed_single_vma(vma, start, end);
821         else if (behavior == MADV_FREE)
822                 return madvise_free_single_vma(vma, start, end);
823         else
824                 return -EINVAL;
825 }
826
827 static long madvise_populate(struct vm_area_struct *vma,
828                              struct vm_area_struct **prev,
829                              unsigned long start, unsigned long end,
830                              int behavior)
831 {
832         const bool write = behavior == MADV_POPULATE_WRITE;
833         struct mm_struct *mm = vma->vm_mm;
834         unsigned long tmp_end;
835         int locked = 1;
836         long pages;
837
838         *prev = vma;
839
840         while (start < end) {
841                 /*
842                  * We might have temporarily dropped the lock. For example,
843                  * our VMA might have been split.
844                  */
845                 if (!vma || start >= vma->vm_end) {
846                         vma = find_vma(mm, start);
847                         if (!vma || start < vma->vm_start)
848                                 return -ENOMEM;
849                 }
850
851                 tmp_end = min_t(unsigned long, end, vma->vm_end);
852                 /* Populate (prefault) page tables readable/writable. */
853                 pages = faultin_vma_page_range(vma, start, tmp_end, write,
854                                                &locked);
855                 if (!locked) {
856                         mmap_read_lock(mm);
857                         locked = 1;
858                         *prev = NULL;
859                         vma = NULL;
860                 }
861                 if (pages < 0) {
862                         switch (pages) {
863                         case -EINTR:
864                                 return -EINTR;
865                         case -EINVAL: /* Incompatible mappings / permissions. */
866                                 return -EINVAL;
867                         case -EHWPOISON:
868                                 return -EHWPOISON;
869                         case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
870                                 return -EFAULT;
871                         default:
872                                 pr_warn_once("%s: unhandled return value: %ld\n",
873                                              __func__, pages);
874                                 fallthrough;
875                         case -ENOMEM:
876                                 return -ENOMEM;
877                         }
878                 }
879                 start += pages * PAGE_SIZE;
880         }
881         return 0;
882 }
883
884 /*
885  * Application wants to free up the pages and associated backing store.
886  * This is effectively punching a hole into the middle of a file.
887  */
888 static long madvise_remove(struct vm_area_struct *vma,
889                                 struct vm_area_struct **prev,
890                                 unsigned long start, unsigned long end)
891 {
892         loff_t offset;
893         int error;
894         struct file *f;
895         struct mm_struct *mm = vma->vm_mm;
896
897         *prev = NULL;   /* tell sys_madvise we drop mmap_lock */
898
899         if (vma->vm_flags & VM_LOCKED)
900                 return -EINVAL;
901
902         f = vma->vm_file;
903
904         if (!f || !f->f_mapping || !f->f_mapping->host) {
905                         return -EINVAL;
906         }
907
908         if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
909                 return -EACCES;
910
911         offset = (loff_t)(start - vma->vm_start)
912                         + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
913
914         /*
915          * Filesystem's fallocate may need to take i_mutex.  We need to
916          * explicitly grab a reference because the vma (and hence the
917          * vma's reference to the file) can go away as soon as we drop
918          * mmap_lock.
919          */
920         get_file(f);
921         if (userfaultfd_remove(vma, start, end)) {
922                 /* mmap_lock was not released by userfaultfd_remove() */
923                 mmap_read_unlock(mm);
924         }
925         error = vfs_fallocate(f,
926                                 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
927                                 offset, end - start);
928         fput(f);
929         mmap_read_lock(mm);
930         return error;
931 }
932
933 #ifdef CONFIG_MEMORY_FAILURE
934 /*
935  * Error injection support for memory error handling.
936  */
937 static int madvise_inject_error(int behavior,
938                 unsigned long start, unsigned long end)
939 {
940         unsigned long size;
941
942         if (!capable(CAP_SYS_ADMIN))
943                 return -EPERM;
944
945
946         for (; start < end; start += size) {
947                 unsigned long pfn;
948                 struct page *page;
949                 int ret;
950
951                 ret = get_user_pages_fast(start, 1, 0, &page);
952                 if (ret != 1)
953                         return ret;
954                 pfn = page_to_pfn(page);
955
956                 /*
957                  * When soft offlining hugepages, after migrating the page
958                  * we dissolve it, therefore in the second loop "page" will
959                  * no longer be a compound page.
960                  */
961                 size = page_size(compound_head(page));
962
963                 if (behavior == MADV_SOFT_OFFLINE) {
964                         pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
965                                  pfn, start);
966                         ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
967                 } else {
968                         pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
969                                  pfn, start);
970                         ret = memory_failure(pfn, MF_COUNT_INCREASED);
971                 }
972
973                 if (ret)
974                         return ret;
975         }
976
977         return 0;
978 }
979 #endif
980
981 static long
982 madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
983                 unsigned long start, unsigned long end, int behavior)
984 {
985         switch (behavior) {
986         case MADV_REMOVE:
987                 return madvise_remove(vma, prev, start, end);
988         case MADV_WILLNEED:
989                 return madvise_willneed(vma, prev, start, end);
990         case MADV_COLD:
991                 return madvise_cold(vma, prev, start, end);
992         case MADV_PAGEOUT:
993                 return madvise_pageout(vma, prev, start, end);
994         case MADV_FREE:
995         case MADV_DONTNEED:
996                 return madvise_dontneed_free(vma, prev, start, end, behavior);
997         case MADV_POPULATE_READ:
998         case MADV_POPULATE_WRITE:
999                 return madvise_populate(vma, prev, start, end, behavior);
1000         default:
1001                 return madvise_behavior(vma, prev, start, end, behavior);
1002         }
1003 }
1004
1005 static bool
1006 madvise_behavior_valid(int behavior)
1007 {
1008         switch (behavior) {
1009         case MADV_DOFORK:
1010         case MADV_DONTFORK:
1011         case MADV_NORMAL:
1012         case MADV_SEQUENTIAL:
1013         case MADV_RANDOM:
1014         case MADV_REMOVE:
1015         case MADV_WILLNEED:
1016         case MADV_DONTNEED:
1017         case MADV_FREE:
1018         case MADV_COLD:
1019         case MADV_PAGEOUT:
1020         case MADV_POPULATE_READ:
1021         case MADV_POPULATE_WRITE:
1022 #ifdef CONFIG_KSM
1023         case MADV_MERGEABLE:
1024         case MADV_UNMERGEABLE:
1025 #endif
1026 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1027         case MADV_HUGEPAGE:
1028         case MADV_NOHUGEPAGE:
1029 #endif
1030         case MADV_DONTDUMP:
1031         case MADV_DODUMP:
1032         case MADV_WIPEONFORK:
1033         case MADV_KEEPONFORK:
1034 #ifdef CONFIG_MEMORY_FAILURE
1035         case MADV_SOFT_OFFLINE:
1036         case MADV_HWPOISON:
1037 #endif
1038                 return true;
1039
1040         default:
1041                 return false;
1042         }
1043 }
1044
1045 static bool
1046 process_madvise_behavior_valid(int behavior)
1047 {
1048         switch (behavior) {
1049         case MADV_COLD:
1050         case MADV_PAGEOUT:
1051                 return true;
1052         default:
1053                 return false;
1054         }
1055 }
1056
1057 /*
1058  * The madvise(2) system call.
1059  *
1060  * Applications can use madvise() to advise the kernel how it should
1061  * handle paging I/O in this VM area.  The idea is to help the kernel
1062  * use appropriate read-ahead and caching techniques.  The information
1063  * provided is advisory only, and can be safely disregarded by the
1064  * kernel without affecting the correct operation of the application.
1065  *
1066  * behavior values:
1067  *  MADV_NORMAL - the default behavior is to read clusters.  This
1068  *              results in some read-ahead and read-behind.
1069  *  MADV_RANDOM - the system should read the minimum amount of data
1070  *              on any access, since it is unlikely that the appli-
1071  *              cation will need more than what it asks for.
1072  *  MADV_SEQUENTIAL - pages in the given range will probably be accessed
1073  *              once, so they can be aggressively read ahead, and
1074  *              can be freed soon after they are accessed.
1075  *  MADV_WILLNEED - the application is notifying the system to read
1076  *              some pages ahead.
1077  *  MADV_DONTNEED - the application is finished with the given range,
1078  *              so the kernel can free resources associated with it.
1079  *  MADV_FREE - the application marks pages in the given range as lazy free,
1080  *              where actual purges are postponed until memory pressure happens.
1081  *  MADV_REMOVE - the application wants to free up the given range of
1082  *              pages and associated backing store.
1083  *  MADV_DONTFORK - omit this area from child's address space when forking:
1084  *              typically, to avoid COWing pages pinned by get_user_pages().
1085  *  MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1086  *  MADV_WIPEONFORK - present the child process with zero-filled memory in this
1087  *              range after a fork.
1088  *  MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1089  *  MADV_HWPOISON - trigger memory error handler as if the given memory range
1090  *              were corrupted by unrecoverable hardware memory failure.
1091  *  MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1092  *  MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1093  *              this area with pages of identical content from other such areas.
1094  *  MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1095  *  MADV_HUGEPAGE - the application wants to back the given range by transparent
1096  *              huge pages in the future. Existing pages might be coalesced and
1097  *              new pages might be allocated as THP.
1098  *  MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1099  *              transparent huge pages so the existing pages will not be
1100  *              coalesced into THP and new pages will not be allocated as THP.
1101  *  MADV_DONTDUMP - the application wants to prevent pages in the given range
1102  *              from being included in its core dump.
1103  *  MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1104  *  MADV_COLD - the application is not expected to use this memory soon,
1105  *              deactivate pages in this range so that they can be reclaimed
1106  *              easily if memory pressure happens.
1107  *  MADV_PAGEOUT - the application is not expected to use this memory soon,
1108  *              page out the pages in this range immediately.
1109  *  MADV_POPULATE_READ - populate (prefault) page tables readable by
1110  *              triggering read faults if required
1111  *  MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1112  *              triggering write faults if required
1113  *
1114  * return values:
1115  *  zero    - success
1116  *  -EINVAL - start + len < 0, start is not page-aligned,
1117  *              "behavior" is not a valid value, or application
1118  *              is attempting to release locked or shared pages,
1119  *              or the specified address range includes file, Huge TLB,
1120  *              MAP_SHARED or VMPFNMAP range.
1121  *  -ENOMEM - addresses in the specified range are not currently
1122  *              mapped, or are outside the AS of the process.
1123  *  -EIO    - an I/O error occurred while paging in data.
1124  *  -EBADF  - map exists, but area maps something that isn't a file.
1125  *  -EAGAIN - a kernel resource was temporarily unavailable.
1126  */
1127 int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1128 {
1129         unsigned long end, tmp;
1130         struct vm_area_struct *vma, *prev;
1131         int unmapped_error = 0;
1132         int error = -EINVAL;
1133         int write;
1134         size_t len;
1135         struct blk_plug plug;
1136
1137         start = untagged_addr(start);
1138
1139         if (!madvise_behavior_valid(behavior))
1140                 return error;
1141
1142         if (!PAGE_ALIGNED(start))
1143                 return error;
1144         len = PAGE_ALIGN(len_in);
1145
1146         /* Check to see whether len was rounded up from small -ve to zero */
1147         if (len_in && !len)
1148                 return error;
1149
1150         end = start + len;
1151         if (end < start)
1152                 return error;
1153
1154         error = 0;
1155         if (end == start)
1156                 return error;
1157
1158 #ifdef CONFIG_MEMORY_FAILURE
1159         if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1160                 return madvise_inject_error(behavior, start, start + len_in);
1161 #endif
1162
1163         write = madvise_need_mmap_write(behavior);
1164         if (write) {
1165                 if (mmap_write_lock_killable(mm))
1166                         return -EINTR;
1167         } else {
1168                 mmap_read_lock(mm);
1169         }
1170
1171         /*
1172          * If the interval [start,end) covers some unmapped address
1173          * ranges, just ignore them, but return -ENOMEM at the end.
1174          * - different from the way of handling in mlock etc.
1175          */
1176         vma = find_vma_prev(mm, start, &prev);
1177         if (vma && start > vma->vm_start)
1178                 prev = vma;
1179
1180         blk_start_plug(&plug);
1181         for (;;) {
1182                 /* Still start < end. */
1183                 error = -ENOMEM;
1184                 if (!vma)
1185                         goto out;
1186
1187                 /* Here start < (end|vma->vm_end). */
1188                 if (start < vma->vm_start) {
1189                         unmapped_error = -ENOMEM;
1190                         start = vma->vm_start;
1191                         if (start >= end)
1192                                 goto out;
1193                 }
1194
1195                 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1196                 tmp = vma->vm_end;
1197                 if (end < tmp)
1198                         tmp = end;
1199
1200                 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1201                 error = madvise_vma(vma, &prev, start, tmp, behavior);
1202                 if (error)
1203                         goto out;
1204                 start = tmp;
1205                 if (prev && start < prev->vm_end)
1206                         start = prev->vm_end;
1207                 error = unmapped_error;
1208                 if (start >= end)
1209                         goto out;
1210                 if (prev)
1211                         vma = prev->vm_next;
1212                 else    /* madvise_remove dropped mmap_lock */
1213                         vma = find_vma(mm, start);
1214         }
1215 out:
1216         blk_finish_plug(&plug);
1217         if (write)
1218                 mmap_write_unlock(mm);
1219         else
1220                 mmap_read_unlock(mm);
1221
1222         return error;
1223 }
1224
1225 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1226 {
1227         return do_madvise(current->mm, start, len_in, behavior);
1228 }
1229
1230 SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1231                 size_t, vlen, int, behavior, unsigned int, flags)
1232 {
1233         ssize_t ret;
1234         struct iovec iovstack[UIO_FASTIOV], iovec;
1235         struct iovec *iov = iovstack;
1236         struct iov_iter iter;
1237         struct pid *pid;
1238         struct task_struct *task;
1239         struct mm_struct *mm;
1240         size_t total_len;
1241         unsigned int f_flags;
1242
1243         if (flags != 0) {
1244                 ret = -EINVAL;
1245                 goto out;
1246         }
1247
1248         ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1249         if (ret < 0)
1250                 goto out;
1251
1252         pid = pidfd_get_pid(pidfd, &f_flags);
1253         if (IS_ERR(pid)) {
1254                 ret = PTR_ERR(pid);
1255                 goto free_iov;
1256         }
1257
1258         task = get_pid_task(pid, PIDTYPE_PID);
1259         if (!task) {
1260                 ret = -ESRCH;
1261                 goto put_pid;
1262         }
1263
1264         if (!process_madvise_behavior_valid(behavior)) {
1265                 ret = -EINVAL;
1266                 goto release_task;
1267         }
1268
1269         /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1270         mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1271         if (IS_ERR_OR_NULL(mm)) {
1272                 ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
1273                 goto release_task;
1274         }
1275
1276         /*
1277          * Require CAP_SYS_NICE for influencing process performance. Note that
1278          * only non-destructive hints are currently supported.
1279          */
1280         if (!capable(CAP_SYS_NICE)) {
1281                 ret = -EPERM;
1282                 goto release_mm;
1283         }
1284
1285         total_len = iov_iter_count(&iter);
1286
1287         while (iov_iter_count(&iter)) {
1288                 iovec = iov_iter_iovec(&iter);
1289                 ret = do_madvise(mm, (unsigned long)iovec.iov_base,
1290                                         iovec.iov_len, behavior);
1291                 if (ret < 0)
1292                         break;
1293                 iov_iter_advance(&iter, iovec.iov_len);
1294         }
1295
1296         if (ret == 0)
1297                 ret = total_len - iov_iter_count(&iter);
1298
1299 release_mm:
1300         mmput(mm);
1301 release_task:
1302         put_task_struct(task);
1303 put_pid:
1304         put_pid(pid);
1305 free_iov:
1306         kfree(iov);
1307 out:
1308         return ret;
1309 }