1 /*
2 * linux/mm/madvise.c
3 *
4 * Copyright (C) 1999 Linus Torvalds
5 * Copyright (C) 2002 Christoph Hellwig
6 */
7
8 #include <linux/mman.h>
9 #include <linux/pagemap.h>
10 #include <linux/syscalls.h>
11 #include <linux/mempolicy.h>
12 #include <linux/page-isolation.h>
13 #include <linux/hugetlb.h>
14 #include <linux/falloc.h>
15 #include <linux/sched.h>
16 #include <linux/ksm.h>
17 #include <linux/fs.h>
18 #include <linux/file.h>
19 #include <linux/blkdev.h>
20 #include <linux/backing-dev.h>
21 #include <linux/swap.h>
22 #include <linux/swapops.h>
23 #include <linux/mmu_notifier.h>
24 #include "internal.h"
25
26 #include <asm/tlb.h>
27
28 /*
29 * Any behaviour which results in changes to the vma->vm_flags needs to
30 * take mmap_sem for writing. Others, which simply traverse vmas, need
31 * to only take it for reading.
32 */
madvise_need_mmap_write(int behavior)33 static int madvise_need_mmap_write(int behavior)
34 {
35 switch (behavior) {
36 case MADV_REMOVE:
37 case MADV_WILLNEED:
38 case MADV_DONTNEED:
39 case MADV_FREE:
40 return 0;
41 default:
42 /* be safe, default to 1. list exceptions explicitly */
43 return 1;
44 }
45 }
46
47 /*
48 * We can potentially split a vm area into separate
49 * areas, each area with its own behavior.
50 */
madvise_behavior(struct vm_area_struct * vma,struct vm_area_struct ** prev,unsigned long start,unsigned long end,int behavior)51 static long madvise_behavior(struct vm_area_struct *vma,
52 struct vm_area_struct **prev,
53 unsigned long start, unsigned long end, int behavior)
54 {
55 struct mm_struct *mm = vma->vm_mm;
56 int error = 0;
57 pgoff_t pgoff;
58 unsigned long new_flags = vma->vm_flags;
59
60 switch (behavior) {
61 case MADV_NORMAL:
62 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
63 break;
64 case MADV_SEQUENTIAL:
65 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
66 break;
67 case MADV_RANDOM:
68 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
69 break;
70 case MADV_DONTFORK:
71 new_flags |= VM_DONTCOPY;
72 break;
73 case MADV_DOFORK:
74 if (vma->vm_flags & VM_IO) {
75 error = -EINVAL;
76 goto out;
77 }
78 new_flags &= ~VM_DONTCOPY;
79 break;
80 case MADV_DONTDUMP:
81 new_flags |= VM_DONTDUMP;
82 break;
83 case MADV_DODUMP:
84 if (new_flags & VM_SPECIAL) {
85 error = -EINVAL;
86 goto out;
87 }
88 new_flags &= ~VM_DONTDUMP;
89 break;
90 case MADV_MERGEABLE:
91 case MADV_UNMERGEABLE:
92 error = ksm_madvise(vma, start, end, behavior, &new_flags);
93 if (error)
94 goto out;
95 break;
96 case MADV_HUGEPAGE:
97 case MADV_NOHUGEPAGE:
98 error = hugepage_madvise(vma, &new_flags, behavior);
99 if (error)
100 goto out;
101 break;
102 }
103
104 if (new_flags == vma->vm_flags) {
105 *prev = vma;
106 goto out;
107 }
108
109 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
110 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
111 vma->vm_file, pgoff, vma_policy(vma),
112 vma->vm_userfaultfd_ctx, vma_get_anon_name(vma));
113 if (*prev) {
114 vma = *prev;
115 goto success;
116 }
117
118 *prev = vma;
119
120 if (start != vma->vm_start) {
121 error = split_vma(mm, vma, start, 1);
122 if (error)
123 goto out;
124 }
125
126 if (end != vma->vm_end) {
127 error = split_vma(mm, vma, end, 0);
128 if (error)
129 goto out;
130 }
131
132 success:
133 /*
134 * vm_flags is protected by the mmap_sem held in write mode.
135 */
136 vma->vm_flags = new_flags;
137
138 out:
139 if (error == -ENOMEM)
140 error = -EAGAIN;
141 return error;
142 }
143
144 #ifdef CONFIG_SWAP
swapin_walk_pmd_entry(pmd_t * pmd,unsigned long start,unsigned long end,struct mm_walk * walk)145 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
146 unsigned long end, struct mm_walk *walk)
147 {
148 pte_t *orig_pte;
149 struct vm_area_struct *vma = walk->private;
150 unsigned long index;
151
152 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
153 return 0;
154
155 for (index = start; index != end; index += PAGE_SIZE) {
156 pte_t pte;
157 swp_entry_t entry;
158 struct page *page;
159 spinlock_t *ptl;
160
161 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
162 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
163 pte_unmap_unlock(orig_pte, ptl);
164
165 if (pte_present(pte) || pte_none(pte))
166 continue;
167 entry = pte_to_swp_entry(pte);
168 if (unlikely(non_swap_entry(entry)))
169 continue;
170
171 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
172 vma, index);
173 if (page)
174 put_page(page);
175 }
176
177 return 0;
178 }
179
force_swapin_readahead(struct vm_area_struct * vma,unsigned long start,unsigned long end)180 static void force_swapin_readahead(struct vm_area_struct *vma,
181 unsigned long start, unsigned long end)
182 {
183 struct mm_walk walk = {
184 .mm = vma->vm_mm,
185 .pmd_entry = swapin_walk_pmd_entry,
186 .private = vma,
187 };
188
189 walk_page_range(start, end, &walk);
190
191 lru_add_drain(); /* Push any new pages onto the LRU now */
192 }
193
force_shm_swapin_readahead(struct vm_area_struct * vma,unsigned long start,unsigned long end,struct address_space * mapping)194 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
195 unsigned long start, unsigned long end,
196 struct address_space *mapping)
197 {
198 pgoff_t index;
199 struct page *page;
200 swp_entry_t swap;
201
202 for (; start < end; start += PAGE_SIZE) {
203 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
204
205 page = find_get_entry(mapping, index);
206 if (!radix_tree_exceptional_entry(page)) {
207 if (page)
208 put_page(page);
209 continue;
210 }
211 swap = radix_to_swp_entry(page);
212 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
213 NULL, 0);
214 if (page)
215 put_page(page);
216 }
217
218 lru_add_drain(); /* Push any new pages onto the LRU now */
219 }
220 #endif /* CONFIG_SWAP */
221
222 /*
223 * Schedule all required I/O operations. Do not wait for completion.
224 */
madvise_willneed(struct vm_area_struct * vma,struct vm_area_struct ** prev,unsigned long start,unsigned long end)225 static long madvise_willneed(struct vm_area_struct *vma,
226 struct vm_area_struct **prev,
227 unsigned long start, unsigned long end)
228 {
229 struct file *file = vma->vm_file;
230
231 *prev = vma;
232 #ifdef CONFIG_SWAP
233 if (!file) {
234 force_swapin_readahead(vma, start, end);
235 return 0;
236 }
237
238 if (shmem_mapping(file->f_mapping)) {
239 force_shm_swapin_readahead(vma, start, end,
240 file->f_mapping);
241 return 0;
242 }
243 #else
244 if (!file)
245 return -EBADF;
246 #endif
247
248 if (IS_DAX(file_inode(file))) {
249 /* no bad return value, but ignore advice */
250 return 0;
251 }
252
253 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
254 if (end > vma->vm_end)
255 end = vma->vm_end;
256 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
257
258 force_page_cache_readahead(file->f_mapping, file, start, end - start);
259 return 0;
260 }
261
madvise_free_pte_range(pmd_t * pmd,unsigned long addr,unsigned long end,struct mm_walk * walk)262 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
263 unsigned long end, struct mm_walk *walk)
264
265 {
266 struct mmu_gather *tlb = walk->private;
267 struct mm_struct *mm = tlb->mm;
268 struct vm_area_struct *vma = walk->vma;
269 spinlock_t *ptl;
270 pte_t *orig_pte, *pte, ptent;
271 struct page *page;
272 int nr_swap = 0;
273 unsigned long next;
274
275 next = pmd_addr_end(addr, end);
276 if (pmd_trans_huge(*pmd))
277 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
278 goto next;
279
280 if (pmd_trans_unstable(pmd))
281 return 0;
282
283 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
284 flush_tlb_batched_pending(mm);
285 arch_enter_lazy_mmu_mode();
286 for (; addr != end; pte++, addr += PAGE_SIZE) {
287 ptent = *pte;
288
289 if (pte_none(ptent))
290 continue;
291 /*
292 * If the pte has swp_entry, just clear page table to
293 * prevent swap-in which is more expensive rather than
294 * (page allocation + zeroing).
295 */
296 if (!pte_present(ptent)) {
297 swp_entry_t entry;
298
299 entry = pte_to_swp_entry(ptent);
300 if (non_swap_entry(entry))
301 continue;
302 nr_swap--;
303 free_swap_and_cache(entry);
304 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
305 continue;
306 }
307
308 page = vm_normal_page(vma, addr, ptent);
309 if (!page)
310 continue;
311
312 /*
313 * If pmd isn't transhuge but the page is THP and
314 * is owned by only this process, split it and
315 * deactivate all pages.
316 */
317 if (PageTransCompound(page)) {
318 if (page_mapcount(page) != 1)
319 goto out;
320 get_page(page);
321 if (!trylock_page(page)) {
322 put_page(page);
323 goto out;
324 }
325 pte_unmap_unlock(orig_pte, ptl);
326 if (split_huge_page(page)) {
327 unlock_page(page);
328 put_page(page);
329 pte_offset_map_lock(mm, pmd, addr, &ptl);
330 goto out;
331 }
332 unlock_page(page);
333 put_page(page);
334 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
335 pte--;
336 addr -= PAGE_SIZE;
337 continue;
338 }
339
340 VM_BUG_ON_PAGE(PageTransCompound(page), page);
341
342 if (PageSwapCache(page) || PageDirty(page)) {
343 if (!trylock_page(page))
344 continue;
345 /*
346 * If page is shared with others, we couldn't clear
347 * PG_dirty of the page.
348 */
349 if (page_mapcount(page) != 1) {
350 unlock_page(page);
351 continue;
352 }
353
354 if (PageSwapCache(page) && !try_to_free_swap(page)) {
355 unlock_page(page);
356 continue;
357 }
358
359 ClearPageDirty(page);
360 unlock_page(page);
361 }
362
363 if (pte_young(ptent) || pte_dirty(ptent)) {
364 /*
365 * Some of architecture(ex, PPC) don't update TLB
366 * with set_pte_at and tlb_remove_tlb_entry so for
367 * the portability, remap the pte with old|clean
368 * after pte clearing.
369 */
370 ptent = ptep_get_and_clear_full(mm, addr, pte,
371 tlb->fullmm);
372
373 ptent = pte_mkold(ptent);
374 ptent = pte_mkclean(ptent);
375 set_pte_at(mm, addr, pte, ptent);
376 if (PageActive(page))
377 deactivate_page(page);
378 tlb_remove_tlb_entry(tlb, pte, addr);
379 }
380 }
381 out:
382 if (nr_swap) {
383 if (current->mm == mm)
384 sync_mm_rss(mm);
385
386 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
387 }
388 arch_leave_lazy_mmu_mode();
389 pte_unmap_unlock(orig_pte, ptl);
390 cond_resched();
391 next:
392 return 0;
393 }
394
madvise_free_page_range(struct mmu_gather * tlb,struct vm_area_struct * vma,unsigned long addr,unsigned long end)395 static void madvise_free_page_range(struct mmu_gather *tlb,
396 struct vm_area_struct *vma,
397 unsigned long addr, unsigned long end)
398 {
399 struct mm_walk free_walk = {
400 .pmd_entry = madvise_free_pte_range,
401 .mm = vma->vm_mm,
402 .private = tlb,
403 };
404
405 tlb_start_vma(tlb, vma);
406 walk_page_range(addr, end, &free_walk);
407 tlb_end_vma(tlb, vma);
408 }
409
madvise_free_single_vma(struct vm_area_struct * vma,unsigned long start_addr,unsigned long end_addr)410 static int madvise_free_single_vma(struct vm_area_struct *vma,
411 unsigned long start_addr, unsigned long end_addr)
412 {
413 unsigned long start, end;
414 struct mm_struct *mm = vma->vm_mm;
415 struct mmu_gather tlb;
416
417 if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
418 return -EINVAL;
419
420 /* MADV_FREE works for only anon vma at the moment */
421 if (!vma_is_anonymous(vma))
422 return -EINVAL;
423
424 start = max(vma->vm_start, start_addr);
425 if (start >= vma->vm_end)
426 return -EINVAL;
427 end = min(vma->vm_end, end_addr);
428 if (end <= vma->vm_start)
429 return -EINVAL;
430
431 lru_add_drain();
432 tlb_gather_mmu(&tlb, mm, start, end);
433 update_hiwater_rss(mm);
434
435 mmu_notifier_invalidate_range_start(mm, start, end);
436 madvise_free_page_range(&tlb, vma, start, end);
437 mmu_notifier_invalidate_range_end(mm, start, end);
438 tlb_finish_mmu(&tlb, start, end);
439
440 return 0;
441 }
442
madvise_free(struct vm_area_struct * vma,struct vm_area_struct ** prev,unsigned long start,unsigned long end)443 static long madvise_free(struct vm_area_struct *vma,
444 struct vm_area_struct **prev,
445 unsigned long start, unsigned long end)
446 {
447 *prev = vma;
448 return madvise_free_single_vma(vma, start, end);
449 }
450
451 /*
452 * Application no longer needs these pages. If the pages are dirty,
453 * it's OK to just throw them away. The app will be more careful about
454 * data it wants to keep. Be sure to free swap resources too. The
455 * zap_page_range call sets things up for shrink_active_list to actually free
456 * these pages later if no one else has touched them in the meantime,
457 * although we could add these pages to a global reuse list for
458 * shrink_active_list to pick up before reclaiming other pages.
459 *
460 * NB: This interface discards data rather than pushes it out to swap,
461 * as some implementations do. This has performance implications for
462 * applications like large transactional databases which want to discard
463 * pages in anonymous maps after committing to backing store the data
464 * that was kept in them. There is no reason to write this data out to
465 * the swap area if the application is discarding it.
466 *
467 * An interface that causes the system to free clean pages and flush
468 * dirty pages is already available as msync(MS_INVALIDATE).
469 */
madvise_dontneed(struct vm_area_struct * vma,struct vm_area_struct ** prev,unsigned long start,unsigned long end)470 static long madvise_dontneed(struct vm_area_struct *vma,
471 struct vm_area_struct **prev,
472 unsigned long start, unsigned long end)
473 {
474 *prev = vma;
475 if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
476 return -EINVAL;
477
478 zap_page_range(vma, start, end - start, NULL);
479 return 0;
480 }
481
482 /*
483 * Application wants to free up the pages and associated backing store.
484 * This is effectively punching a hole into the middle of a file.
485 */
madvise_remove(struct vm_area_struct * vma,struct vm_area_struct ** prev,unsigned long start,unsigned long end)486 static long madvise_remove(struct vm_area_struct *vma,
487 struct vm_area_struct **prev,
488 unsigned long start, unsigned long end)
489 {
490 loff_t offset;
491 int error;
492 struct file *f;
493
494 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
495
496 if (vma->vm_flags & VM_LOCKED)
497 return -EINVAL;
498
499 f = vma->vm_file;
500
501 if (!f || !f->f_mapping || !f->f_mapping->host) {
502 return -EINVAL;
503 }
504
505 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
506 return -EACCES;
507
508 offset = (loff_t)(start - vma->vm_start)
509 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
510
511 /*
512 * Filesystem's fallocate may need to take i_mutex. We need to
513 * explicitly grab a reference because the vma (and hence the
514 * vma's reference to the file) can go away as soon as we drop
515 * mmap_sem.
516 */
517 get_file(f);
518 up_read(¤t->mm->mmap_sem);
519 error = vfs_fallocate(f,
520 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
521 offset, end - start);
522 fput(f);
523 down_read(¤t->mm->mmap_sem);
524 return error;
525 }
526
527 #ifdef CONFIG_MEMORY_FAILURE
528 /*
529 * Error injection support for memory error handling.
530 */
madvise_hwpoison(int bhv,unsigned long start,unsigned long end)531 static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
532 {
533 struct page *p;
534 struct zone *zone;
535
536 if (!capable(CAP_SYS_ADMIN))
537 return -EPERM;
538 for (; start < end; start += PAGE_SIZE <<
539 compound_order(compound_head(p))) {
540 int ret;
541
542 ret = get_user_pages_fast(start, 1, 0, &p);
543 if (ret != 1)
544 return ret;
545
546 if (PageHWPoison(p)) {
547 put_page(p);
548 continue;
549 }
550 if (bhv == MADV_SOFT_OFFLINE) {
551 pr_info("Soft offlining page %#lx at %#lx\n",
552 page_to_pfn(p), start);
553 ret = soft_offline_page(p, MF_COUNT_INCREASED);
554 if (ret)
555 return ret;
556 continue;
557 }
558 pr_info("Injecting memory failure for page %#lx at %#lx\n",
559 page_to_pfn(p), start);
560 ret = memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
561 if (ret)
562 return ret;
563 }
564
565 /* Ensure that all poisoned pages are removed from per-cpu lists */
566 for_each_populated_zone(zone)
567 drain_all_pages(zone);
568
569 return 0;
570 }
571 #endif
572
573 static long
madvise_vma(struct vm_area_struct * vma,struct vm_area_struct ** prev,unsigned long start,unsigned long end,int behavior)574 madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
575 unsigned long start, unsigned long end, int behavior)
576 {
577 switch (behavior) {
578 case MADV_REMOVE:
579 return madvise_remove(vma, prev, start, end);
580 case MADV_WILLNEED:
581 return madvise_willneed(vma, prev, start, end);
582 case MADV_FREE:
583 /*
584 * XXX: In this implementation, MADV_FREE works like
585 * MADV_DONTNEED on swapless system or full swap.
586 */
587 if (get_nr_swap_pages() > 0)
588 return madvise_free(vma, prev, start, end);
589 /* passthrough */
590 case MADV_DONTNEED:
591 return madvise_dontneed(vma, prev, start, end);
592 default:
593 return madvise_behavior(vma, prev, start, end, behavior);
594 }
595 }
596
597 static bool
madvise_behavior_valid(int behavior)598 madvise_behavior_valid(int behavior)
599 {
600 switch (behavior) {
601 case MADV_DOFORK:
602 case MADV_DONTFORK:
603 case MADV_NORMAL:
604 case MADV_SEQUENTIAL:
605 case MADV_RANDOM:
606 case MADV_REMOVE:
607 case MADV_WILLNEED:
608 case MADV_DONTNEED:
609 case MADV_FREE:
610 #ifdef CONFIG_KSM
611 case MADV_MERGEABLE:
612 case MADV_UNMERGEABLE:
613 #endif
614 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
615 case MADV_HUGEPAGE:
616 case MADV_NOHUGEPAGE:
617 #endif
618 case MADV_DONTDUMP:
619 case MADV_DODUMP:
620 return true;
621
622 default:
623 return false;
624 }
625 }
626
627 /*
628 * The madvise(2) system call.
629 *
630 * Applications can use madvise() to advise the kernel how it should
631 * handle paging I/O in this VM area. The idea is to help the kernel
632 * use appropriate read-ahead and caching techniques. The information
633 * provided is advisory only, and can be safely disregarded by the
634 * kernel without affecting the correct operation of the application.
635 *
636 * behavior values:
637 * MADV_NORMAL - the default behavior is to read clusters. This
638 * results in some read-ahead and read-behind.
639 * MADV_RANDOM - the system should read the minimum amount of data
640 * on any access, since it is unlikely that the appli-
641 * cation will need more than what it asks for.
642 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
643 * once, so they can be aggressively read ahead, and
644 * can be freed soon after they are accessed.
645 * MADV_WILLNEED - the application is notifying the system to read
646 * some pages ahead.
647 * MADV_DONTNEED - the application is finished with the given range,
648 * so the kernel can free resources associated with it.
649 * MADV_FREE - the application marks pages in the given range as lazy free,
650 * where actual purges are postponed until memory pressure happens.
651 * MADV_REMOVE - the application wants to free up the given range of
652 * pages and associated backing store.
653 * MADV_DONTFORK - omit this area from child's address space when forking:
654 * typically, to avoid COWing pages pinned by get_user_pages().
655 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
656 * MADV_HWPOISON - trigger memory error handler as if the given memory range
657 * were corrupted by unrecoverable hardware memory failure.
658 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
659 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
660 * this area with pages of identical content from other such areas.
661 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
662 * MADV_HUGEPAGE - the application wants to back the given range by transparent
663 * huge pages in the future. Existing pages might be coalesced and
664 * new pages might be allocated as THP.
665 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
666 * transparent huge pages so the existing pages will not be
667 * coalesced into THP and new pages will not be allocated as THP.
668 * MADV_DONTDUMP - the application wants to prevent pages in the given range
669 * from being included in its core dump.
670 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
671 *
672 * return values:
673 * zero - success
674 * -EINVAL - start + len < 0, start is not page-aligned,
675 * "behavior" is not a valid value, or application
676 * is attempting to release locked or shared pages.
677 * -ENOMEM - addresses in the specified range are not currently
678 * mapped, or are outside the AS of the process.
679 * -EIO - an I/O error occurred while paging in data.
680 * -EBADF - map exists, but area maps something that isn't a file.
681 * -EAGAIN - a kernel resource was temporarily unavailable.
682 */
SYSCALL_DEFINE3(madvise,unsigned long,start,size_t,len_in,int,behavior)683 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
684 {
685 unsigned long end, tmp;
686 struct vm_area_struct *vma, *prev;
687 int unmapped_error = 0;
688 int error = -EINVAL;
689 int write;
690 size_t len;
691 struct blk_plug plug;
692
693 #ifdef CONFIG_MEMORY_FAILURE
694 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
695 return madvise_hwpoison(behavior, start, start+len_in);
696 #endif
697 if (!madvise_behavior_valid(behavior))
698 return error;
699
700 if (start & ~PAGE_MASK)
701 return error;
702 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
703
704 /* Check to see whether len was rounded up from small -ve to zero */
705 if (len_in && !len)
706 return error;
707
708 end = start + len;
709 if (end < start)
710 return error;
711
712 error = 0;
713 if (end == start)
714 return error;
715
716 write = madvise_need_mmap_write(behavior);
717 if (write) {
718 if (down_write_killable(¤t->mm->mmap_sem))
719 return -EINTR;
720 } else {
721 down_read(¤t->mm->mmap_sem);
722 }
723
724 /*
725 * If the interval [start,end) covers some unmapped address
726 * ranges, just ignore them, but return -ENOMEM at the end.
727 * - different from the way of handling in mlock etc.
728 */
729 vma = find_vma_prev(current->mm, start, &prev);
730 if (vma && start > vma->vm_start)
731 prev = vma;
732
733 blk_start_plug(&plug);
734 for (;;) {
735 /* Still start < end. */
736 error = -ENOMEM;
737 if (!vma)
738 goto out;
739
740 /* Here start < (end|vma->vm_end). */
741 if (start < vma->vm_start) {
742 unmapped_error = -ENOMEM;
743 start = vma->vm_start;
744 if (start >= end)
745 goto out;
746 }
747
748 /* Here vma->vm_start <= start < (end|vma->vm_end) */
749 tmp = vma->vm_end;
750 if (end < tmp)
751 tmp = end;
752
753 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
754 error = madvise_vma(vma, &prev, start, tmp, behavior);
755 if (error)
756 goto out;
757 start = tmp;
758 if (prev && start < prev->vm_end)
759 start = prev->vm_end;
760 error = unmapped_error;
761 if (start >= end)
762 goto out;
763 if (prev)
764 vma = prev->vm_next;
765 else /* madvise_remove dropped mmap_sem */
766 vma = find_vma(current->mm, start);
767 }
768 out:
769 blk_finish_plug(&plug);
770 if (write)
771 up_write(¤t->mm->mmap_sem);
772 else
773 up_read(¤t->mm->mmap_sem);
774
775 return error;
776 }
777