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