blob: 6849e4e2be222ff421370b625e81722db2431ba5
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 | */ |
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 | */ |
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 (!is_vm_hugetlb_page(vma) && 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 |
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 | |
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 | |
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 | */ |
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 | |
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 | |
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 | |
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 | |
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 | */ |
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 | */ |
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 | */ |
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 |
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 |
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 | */ |
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 |