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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/swap.h>
21#include <linux/swapops.h>
22
23/*
24 * Any behaviour which results in changes to the vma->vm_flags needs to
25 * take mmap_sem for writing. Others, which simply traverse vmas, need
26 * to only take it for reading.
27 */
28static int madvise_need_mmap_write(int behavior)
29{
30 switch (behavior) {
31 case MADV_REMOVE:
32 case MADV_WILLNEED:
33 case MADV_DONTNEED:
34 return 0;
35 default:
36 /* be safe, default to 1. list exceptions explicitly */
37 return 1;
38 }
39}
40
41/*
42 * We can potentially split a vm area into separate
43 * areas, each area with its own behavior.
44 */
45static long madvise_behavior(struct vm_area_struct *vma,
46 struct vm_area_struct **prev,
47 unsigned long start, unsigned long end, int behavior)
48{
49 struct mm_struct *mm = vma->vm_mm;
50 int error = 0;
51 pgoff_t pgoff;
52 unsigned long new_flags = vma->vm_flags;
53
54 switch (behavior) {
55 case MADV_NORMAL:
56 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
57 break;
58 case MADV_SEQUENTIAL:
59 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
60 break;
61 case MADV_RANDOM:
62 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
63 break;
64 case MADV_DONTFORK:
65 new_flags |= VM_DONTCOPY;
66 break;
67 case MADV_DOFORK:
68 if (vma->vm_flags & VM_IO) {
69 error = -EINVAL;
70 goto out;
71 }
72 new_flags &= ~VM_DONTCOPY;
73 break;
74 case MADV_DONTDUMP:
75 new_flags |= VM_DONTDUMP;
76 break;
77 case MADV_DODUMP:
78 if (new_flags & VM_SPECIAL) {
79 error = -EINVAL;
80 goto out;
81 }
82 new_flags &= ~VM_DONTDUMP;
83 break;
84 case MADV_MERGEABLE:
85 case MADV_UNMERGEABLE:
86 error = ksm_madvise(vma, start, end, behavior, &new_flags);
87 if (error)
88 goto out;
89 break;
90 case MADV_HUGEPAGE:
91 case MADV_NOHUGEPAGE:
92 error = hugepage_madvise(vma, &new_flags, behavior);
93 if (error)
94 goto out;
95 break;
96 }
97
98 if (new_flags == vma->vm_flags) {
99 *prev = vma;
100 goto out;
101 }
102
103 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
104 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
105 vma->vm_file, pgoff, vma_policy(vma));
106 if (*prev) {
107 vma = *prev;
108 goto success;
109 }
110
111 *prev = vma;
112
113 if (start != vma->vm_start) {
114 error = split_vma(mm, vma, start, 1);
115 if (error)
116 goto out;
117 }
118
119 if (end != vma->vm_end) {
120 error = split_vma(mm, vma, end, 0);
121 if (error)
122 goto out;
123 }
124
125success:
126 /*
127 * vm_flags is protected by the mmap_sem held in write mode.
128 */
129 vma->vm_flags = new_flags;
130
131out:
132 if (error == -ENOMEM)
133 error = -EAGAIN;
134 return error;
135}
136
137#ifdef CONFIG_SWAP
138static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
139 unsigned long end, struct mm_walk *walk)
140{
141 pte_t *orig_pte;
142 struct vm_area_struct *vma = walk->private;
143 unsigned long index;
144
145 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
146 return 0;
147
148 for (index = start; index != end; index += PAGE_SIZE) {
149 pte_t pte;
150 swp_entry_t entry;
151 struct page *page;
152 spinlock_t *ptl;
153
154 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
155 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
156 pte_unmap_unlock(orig_pte, ptl);
157
158 if (pte_present(pte) || pte_none(pte) || pte_file(pte))
159 continue;
160 entry = pte_to_swp_entry(pte);
161 if (unlikely(non_swap_entry(entry)))
162 continue;
163
164 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
165 vma, index);
166 if (page)
167 page_cache_release(page);
168 }
169
170 return 0;
171}
172
173static void force_swapin_readahead(struct vm_area_struct *vma,
174 unsigned long start, unsigned long end)
175{
176 struct mm_walk walk = {
177 .mm = vma->vm_mm,
178 .pmd_entry = swapin_walk_pmd_entry,
179 .private = vma,
180 };
181
182 walk_page_range(start, end, &walk);
183
184 lru_add_drain(); /* Push any new pages onto the LRU now */
185}
186
187static void force_shm_swapin_readahead(struct vm_area_struct *vma,
188 unsigned long start, unsigned long end,
189 struct address_space *mapping)
190{
191 pgoff_t index;
192 struct page *page;
193 swp_entry_t swap;
194
195 for (; start < end; start += PAGE_SIZE) {
196 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
197
198 page = find_get_entry(mapping, index);
199 if (!radix_tree_exceptional_entry(page)) {
200 if (page)
201 page_cache_release(page);
202 continue;
203 }
204 swap = radix_to_swp_entry(page);
205 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
206 NULL, 0);
207 if (page)
208 page_cache_release(page);
209 }
210
211 lru_add_drain(); /* Push any new pages onto the LRU now */
212}
213#endif /* CONFIG_SWAP */
214
215/*
216 * Schedule all required I/O operations. Do not wait for completion.
217 */
218static long madvise_willneed(struct vm_area_struct *vma,
219 struct vm_area_struct **prev,
220 unsigned long start, unsigned long end)
221{
222 struct file *file = vma->vm_file;
223
224#ifdef CONFIG_SWAP
225 if (!file || mapping_cap_swap_backed(file->f_mapping)) {
226 *prev = vma;
227 if (!file)
228 force_swapin_readahead(vma, start, end);
229 else
230 force_shm_swapin_readahead(vma, start, end,
231 file->f_mapping);
232 return 0;
233 }
234#endif
235
236 if (!file)
237 return -EBADF;
238
239 if (file->f_mapping->a_ops->get_xip_mem) {
240 /* no bad return value, but ignore advice */
241 return 0;
242 }
243
244 *prev = vma;
245 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
246 if (end > vma->vm_end)
247 end = vma->vm_end;
248 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
249
250 force_page_cache_readahead(file->f_mapping, file, start, end - start);
251 return 0;
252}
253
254/*
255 * Application no longer needs these pages. If the pages are dirty,
256 * it's OK to just throw them away. The app will be more careful about
257 * data it wants to keep. Be sure to free swap resources too. The
258 * zap_page_range call sets things up for shrink_active_list to actually free
259 * these pages later if no one else has touched them in the meantime,
260 * although we could add these pages to a global reuse list for
261 * shrink_active_list to pick up before reclaiming other pages.
262 *
263 * NB: This interface discards data rather than pushes it out to swap,
264 * as some implementations do. This has performance implications for
265 * applications like large transactional databases which want to discard
266 * pages in anonymous maps after committing to backing store the data
267 * that was kept in them. There is no reason to write this data out to
268 * the swap area if the application is discarding it.
269 *
270 * An interface that causes the system to free clean pages and flush
271 * dirty pages is already available as msync(MS_INVALIDATE).
272 */
273static long madvise_dontneed(struct vm_area_struct *vma,
274 struct vm_area_struct **prev,
275 unsigned long start, unsigned long end)
276{
277 *prev = vma;
278 if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
279 return -EINVAL;
280
281 if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
282 struct zap_details details = {
283 .nonlinear_vma = vma,
284 .last_index = ULONG_MAX,
285 };
286 zap_page_range(vma, start, end - start, &details);
287 } else
288 zap_page_range(vma, start, end - start, NULL);
289 return 0;
290}
291
292/*
293 * Application wants to free up the pages and associated backing store.
294 * This is effectively punching a hole into the middle of a file.
295 *
296 * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
297 * Other filesystems return -ENOSYS.
298 */
299static long madvise_remove(struct vm_area_struct *vma,
300 struct vm_area_struct **prev,
301 unsigned long start, unsigned long end)
302{
303 loff_t offset;
304 int error;
305 struct file *f;
306
307 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
308
309 if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB))
310 return -EINVAL;
311
312 f = vma->vm_file;
313
314 if (!f || !f->f_mapping || !f->f_mapping->host) {
315 return -EINVAL;
316 }
317
318 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
319 return -EACCES;
320
321 offset = (loff_t)(start - vma->vm_start)
322 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
323
324 /*
325 * Filesystem's fallocate may need to take i_mutex. We need to
326 * explicitly grab a reference because the vma (and hence the
327 * vma's reference to the file) can go away as soon as we drop
328 * mmap_sem.
329 */
330 get_file(f);
331 up_read(¤t->mm->mmap_sem);
332 error = do_fallocate(f,
333 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
334 offset, end - start);
335 fput(f);
336 down_read(¤t->mm->mmap_sem);
337 return error;
338}
339
340#ifdef CONFIG_MEMORY_FAILURE
341/*
342 * Error injection support for memory error handling.
343 */
344static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
345{
346 struct page *p;
347 if (!capable(CAP_SYS_ADMIN))
348 return -EPERM;
349 for (; start < end; start += PAGE_SIZE <<
350 compound_order(compound_head(p))) {
351 int ret;
352
353 ret = get_user_pages_fast(start, 1, 0, &p);
354 if (ret != 1)
355 return ret;
356
357 if (PageHWPoison(p)) {
358 put_page(p);
359 continue;
360 }
361 if (bhv == MADV_SOFT_OFFLINE) {
362 pr_info("Soft offlining page %#lx at %#lx\n",
363 page_to_pfn(p), start);
364 ret = soft_offline_page(p, MF_COUNT_INCREASED);
365 if (ret)
366 return ret;
367 continue;
368 }
369 pr_info("Injecting memory failure for page %#lx at %#lx\n",
370 page_to_pfn(p), start);
371 /* Ignore return value for now */
372 memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
373 }
374 return 0;
375}
376#endif
377
378static long
379madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
380 unsigned long start, unsigned long end, int behavior)
381{
382 switch (behavior) {
383 case MADV_REMOVE:
384 return madvise_remove(vma, prev, start, end);
385 case MADV_WILLNEED:
386 return madvise_willneed(vma, prev, start, end);
387 case MADV_DONTNEED:
388 return madvise_dontneed(vma, prev, start, end);
389 default:
390 return madvise_behavior(vma, prev, start, end, behavior);
391 }
392}
393
394static int
395madvise_behavior_valid(int behavior)
396{
397 switch (behavior) {
398 case MADV_DOFORK:
399 case MADV_DONTFORK:
400 case MADV_NORMAL:
401 case MADV_SEQUENTIAL:
402 case MADV_RANDOM:
403 case MADV_REMOVE:
404 case MADV_WILLNEED:
405 case MADV_DONTNEED:
406#ifdef CONFIG_KSM
407 case MADV_MERGEABLE:
408 case MADV_UNMERGEABLE:
409#endif
410#ifdef CONFIG_TRANSPARENT_HUGEPAGE
411 case MADV_HUGEPAGE:
412 case MADV_NOHUGEPAGE:
413#endif
414 case MADV_DONTDUMP:
415 case MADV_DODUMP:
416 return 1;
417
418 default:
419 return 0;
420 }
421}
422
423/*
424 * The madvise(2) system call.
425 *
426 * Applications can use madvise() to advise the kernel how it should
427 * handle paging I/O in this VM area. The idea is to help the kernel
428 * use appropriate read-ahead and caching techniques. The information
429 * provided is advisory only, and can be safely disregarded by the
430 * kernel without affecting the correct operation of the application.
431 *
432 * behavior values:
433 * MADV_NORMAL - the default behavior is to read clusters. This
434 * results in some read-ahead and read-behind.
435 * MADV_RANDOM - the system should read the minimum amount of data
436 * on any access, since it is unlikely that the appli-
437 * cation will need more than what it asks for.
438 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
439 * once, so they can be aggressively read ahead, and
440 * can be freed soon after they are accessed.
441 * MADV_WILLNEED - the application is notifying the system to read
442 * some pages ahead.
443 * MADV_DONTNEED - the application is finished with the given range,
444 * so the kernel can free resources associated with it.
445 * MADV_REMOVE - the application wants to free up the given range of
446 * pages and associated backing store.
447 * MADV_DONTFORK - omit this area from child's address space when forking:
448 * typically, to avoid COWing pages pinned by get_user_pages().
449 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
450 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
451 * this area with pages of identical content from other such areas.
452 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
453 *
454 * return values:
455 * zero - success
456 * -EINVAL - start + len < 0, start is not page-aligned,
457 * "behavior" is not a valid value, or application
458 * is attempting to release locked or shared pages.
459 * -ENOMEM - addresses in the specified range are not currently
460 * mapped, or are outside the AS of the process.
461 * -EIO - an I/O error occurred while paging in data.
462 * -EBADF - map exists, but area maps something that isn't a file.
463 * -EAGAIN - a kernel resource was temporarily unavailable.
464 */
465SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
466{
467 unsigned long end, tmp;
468 struct vm_area_struct *vma, *prev;
469 int unmapped_error = 0;
470 int error = -EINVAL;
471 int write;
472 size_t len;
473 struct blk_plug plug;
474
475#ifdef CONFIG_MEMORY_FAILURE
476 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
477 return madvise_hwpoison(behavior, start, start+len_in);
478#endif
479 if (!madvise_behavior_valid(behavior))
480 return error;
481
482 if (start & ~PAGE_MASK)
483 return error;
484 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
485
486 /* Check to see whether len was rounded up from small -ve to zero */
487 if (len_in && !len)
488 return error;
489
490 end = start + len;
491 if (end < start)
492 return error;
493
494 error = 0;
495 if (end == start)
496 return error;
497
498 write = madvise_need_mmap_write(behavior);
499 if (write)
500 down_write(¤t->mm->mmap_sem);
501 else
502 down_read(¤t->mm->mmap_sem);
503
504 /*
505 * If the interval [start,end) covers some unmapped address
506 * ranges, just ignore them, but return -ENOMEM at the end.
507 * - different from the way of handling in mlock etc.
508 */
509 vma = find_vma_prev(current->mm, start, &prev);
510 if (vma && start > vma->vm_start)
511 prev = vma;
512
513 blk_start_plug(&plug);
514 for (;;) {
515 /* Still start < end. */
516 error = -ENOMEM;
517 if (!vma)
518 goto out;
519
520 /* Here start < (end|vma->vm_end). */
521 if (start < vma->vm_start) {
522 unmapped_error = -ENOMEM;
523 start = vma->vm_start;
524 if (start >= end)
525 goto out;
526 }
527
528 /* Here vma->vm_start <= start < (end|vma->vm_end) */
529 tmp = vma->vm_end;
530 if (end < tmp)
531 tmp = end;
532
533 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
534 error = madvise_vma(vma, &prev, start, tmp, behavior);
535 if (error)
536 goto out;
537 start = tmp;
538 if (prev && start < prev->vm_end)
539 start = prev->vm_end;
540 error = unmapped_error;
541 if (start >= end)
542 goto out;
543 if (prev)
544 vma = prev->vm_next;
545 else /* madvise_remove dropped mmap_sem */
546 vma = find_vma(current->mm, start);
547 }
548out:
549 blk_finish_plug(&plug);
550 if (write)
551 up_write(¤t->mm->mmap_sem);
552 else
553 up_read(¤t->mm->mmap_sem);
554
555 return error;
556}
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/sched.h>
15#include <linux/ksm.h>
16
17/*
18 * Any behaviour which results in changes to the vma->vm_flags needs to
19 * take mmap_sem for writing. Others, which simply traverse vmas, need
20 * to only take it for reading.
21 */
22static int madvise_need_mmap_write(int behavior)
23{
24 switch (behavior) {
25 case MADV_REMOVE:
26 case MADV_WILLNEED:
27 case MADV_DONTNEED:
28 return 0;
29 default:
30 /* be safe, default to 1. list exceptions explicitly */
31 return 1;
32 }
33}
34
35/*
36 * We can potentially split a vm area into separate
37 * areas, each area with its own behavior.
38 */
39static long madvise_behavior(struct vm_area_struct * vma,
40 struct vm_area_struct **prev,
41 unsigned long start, unsigned long end, int behavior)
42{
43 struct mm_struct * mm = vma->vm_mm;
44 int error = 0;
45 pgoff_t pgoff;
46 unsigned long new_flags = vma->vm_flags;
47
48 switch (behavior) {
49 case MADV_NORMAL:
50 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
51 break;
52 case MADV_SEQUENTIAL:
53 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
54 break;
55 case MADV_RANDOM:
56 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
57 break;
58 case MADV_DONTFORK:
59 new_flags |= VM_DONTCOPY;
60 break;
61 case MADV_DOFORK:
62 if (vma->vm_flags & VM_IO) {
63 error = -EINVAL;
64 goto out;
65 }
66 new_flags &= ~VM_DONTCOPY;
67 break;
68 case MADV_MERGEABLE:
69 case MADV_UNMERGEABLE:
70 error = ksm_madvise(vma, start, end, behavior, &new_flags);
71 if (error)
72 goto out;
73 break;
74 case MADV_HUGEPAGE:
75 case MADV_NOHUGEPAGE:
76 error = hugepage_madvise(vma, &new_flags, behavior);
77 if (error)
78 goto out;
79 break;
80 }
81
82 if (new_flags == vma->vm_flags) {
83 *prev = vma;
84 goto out;
85 }
86
87 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
88 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
89 vma->vm_file, pgoff, vma_policy(vma));
90 if (*prev) {
91 vma = *prev;
92 goto success;
93 }
94
95 *prev = vma;
96
97 if (start != vma->vm_start) {
98 error = split_vma(mm, vma, start, 1);
99 if (error)
100 goto out;
101 }
102
103 if (end != vma->vm_end) {
104 error = split_vma(mm, vma, end, 0);
105 if (error)
106 goto out;
107 }
108
109success:
110 /*
111 * vm_flags is protected by the mmap_sem held in write mode.
112 */
113 vma->vm_flags = new_flags;
114
115out:
116 if (error == -ENOMEM)
117 error = -EAGAIN;
118 return error;
119}
120
121/*
122 * Schedule all required I/O operations. Do not wait for completion.
123 */
124static long madvise_willneed(struct vm_area_struct * vma,
125 struct vm_area_struct ** prev,
126 unsigned long start, unsigned long end)
127{
128 struct file *file = vma->vm_file;
129
130 if (!file)
131 return -EBADF;
132
133 if (file->f_mapping->a_ops->get_xip_mem) {
134 /* no bad return value, but ignore advice */
135 return 0;
136 }
137
138 *prev = vma;
139 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
140 if (end > vma->vm_end)
141 end = vma->vm_end;
142 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
143
144 force_page_cache_readahead(file->f_mapping, file, start, end - start);
145 return 0;
146}
147
148/*
149 * Application no longer needs these pages. If the pages are dirty,
150 * it's OK to just throw them away. The app will be more careful about
151 * data it wants to keep. Be sure to free swap resources too. The
152 * zap_page_range call sets things up for shrink_active_list to actually free
153 * these pages later if no one else has touched them in the meantime,
154 * although we could add these pages to a global reuse list for
155 * shrink_active_list to pick up before reclaiming other pages.
156 *
157 * NB: This interface discards data rather than pushes it out to swap,
158 * as some implementations do. This has performance implications for
159 * applications like large transactional databases which want to discard
160 * pages in anonymous maps after committing to backing store the data
161 * that was kept in them. There is no reason to write this data out to
162 * the swap area if the application is discarding it.
163 *
164 * An interface that causes the system to free clean pages and flush
165 * dirty pages is already available as msync(MS_INVALIDATE).
166 */
167static long madvise_dontneed(struct vm_area_struct * vma,
168 struct vm_area_struct ** prev,
169 unsigned long start, unsigned long end)
170{
171 *prev = vma;
172 if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
173 return -EINVAL;
174
175 if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
176 struct zap_details details = {
177 .nonlinear_vma = vma,
178 .last_index = ULONG_MAX,
179 };
180 zap_page_range(vma, start, end - start, &details);
181 } else
182 zap_page_range(vma, start, end - start, NULL);
183 return 0;
184}
185
186/*
187 * Application wants to free up the pages and associated backing store.
188 * This is effectively punching a hole into the middle of a file.
189 *
190 * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
191 * Other filesystems return -ENOSYS.
192 */
193static long madvise_remove(struct vm_area_struct *vma,
194 struct vm_area_struct **prev,
195 unsigned long start, unsigned long end)
196{
197 struct address_space *mapping;
198 loff_t offset, endoff;
199 int error;
200
201 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
202
203 if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB))
204 return -EINVAL;
205
206 if (!vma->vm_file || !vma->vm_file->f_mapping
207 || !vma->vm_file->f_mapping->host) {
208 return -EINVAL;
209 }
210
211 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
212 return -EACCES;
213
214 mapping = vma->vm_file->f_mapping;
215
216 offset = (loff_t)(start - vma->vm_start)
217 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
218 endoff = (loff_t)(end - vma->vm_start - 1)
219 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
220
221 /* vmtruncate_range needs to take i_mutex */
222 up_read(¤t->mm->mmap_sem);
223 error = vmtruncate_range(mapping->host, offset, endoff);
224 down_read(¤t->mm->mmap_sem);
225 return error;
226}
227
228#ifdef CONFIG_MEMORY_FAILURE
229/*
230 * Error injection support for memory error handling.
231 */
232static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
233{
234 int ret = 0;
235
236 if (!capable(CAP_SYS_ADMIN))
237 return -EPERM;
238 for (; start < end; start += PAGE_SIZE) {
239 struct page *p;
240 int ret = get_user_pages_fast(start, 1, 0, &p);
241 if (ret != 1)
242 return ret;
243 if (bhv == MADV_SOFT_OFFLINE) {
244 printk(KERN_INFO "Soft offlining page %lx at %lx\n",
245 page_to_pfn(p), start);
246 ret = soft_offline_page(p, MF_COUNT_INCREASED);
247 if (ret)
248 break;
249 continue;
250 }
251 printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n",
252 page_to_pfn(p), start);
253 /* Ignore return value for now */
254 __memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
255 }
256 return ret;
257}
258#endif
259
260static long
261madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
262 unsigned long start, unsigned long end, int behavior)
263{
264 switch (behavior) {
265 case MADV_REMOVE:
266 return madvise_remove(vma, prev, start, end);
267 case MADV_WILLNEED:
268 return madvise_willneed(vma, prev, start, end);
269 case MADV_DONTNEED:
270 return madvise_dontneed(vma, prev, start, end);
271 default:
272 return madvise_behavior(vma, prev, start, end, behavior);
273 }
274}
275
276static int
277madvise_behavior_valid(int behavior)
278{
279 switch (behavior) {
280 case MADV_DOFORK:
281 case MADV_DONTFORK:
282 case MADV_NORMAL:
283 case MADV_SEQUENTIAL:
284 case MADV_RANDOM:
285 case MADV_REMOVE:
286 case MADV_WILLNEED:
287 case MADV_DONTNEED:
288#ifdef CONFIG_KSM
289 case MADV_MERGEABLE:
290 case MADV_UNMERGEABLE:
291#endif
292#ifdef CONFIG_TRANSPARENT_HUGEPAGE
293 case MADV_HUGEPAGE:
294 case MADV_NOHUGEPAGE:
295#endif
296 return 1;
297
298 default:
299 return 0;
300 }
301}
302
303/*
304 * The madvise(2) system call.
305 *
306 * Applications can use madvise() to advise the kernel how it should
307 * handle paging I/O in this VM area. The idea is to help the kernel
308 * use appropriate read-ahead and caching techniques. The information
309 * provided is advisory only, and can be safely disregarded by the
310 * kernel without affecting the correct operation of the application.
311 *
312 * behavior values:
313 * MADV_NORMAL - the default behavior is to read clusters. This
314 * results in some read-ahead and read-behind.
315 * MADV_RANDOM - the system should read the minimum amount of data
316 * on any access, since it is unlikely that the appli-
317 * cation will need more than what it asks for.
318 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
319 * once, so they can be aggressively read ahead, and
320 * can be freed soon after they are accessed.
321 * MADV_WILLNEED - the application is notifying the system to read
322 * some pages ahead.
323 * MADV_DONTNEED - the application is finished with the given range,
324 * so the kernel can free resources associated with it.
325 * MADV_REMOVE - the application wants to free up the given range of
326 * pages and associated backing store.
327 * MADV_DONTFORK - omit this area from child's address space when forking:
328 * typically, to avoid COWing pages pinned by get_user_pages().
329 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
330 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
331 * this area with pages of identical content from other such areas.
332 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
333 *
334 * return values:
335 * zero - success
336 * -EINVAL - start + len < 0, start is not page-aligned,
337 * "behavior" is not a valid value, or application
338 * is attempting to release locked or shared pages.
339 * -ENOMEM - addresses in the specified range are not currently
340 * mapped, or are outside the AS of the process.
341 * -EIO - an I/O error occurred while paging in data.
342 * -EBADF - map exists, but area maps something that isn't a file.
343 * -EAGAIN - a kernel resource was temporarily unavailable.
344 */
345SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
346{
347 unsigned long end, tmp;
348 struct vm_area_struct * vma, *prev;
349 int unmapped_error = 0;
350 int error = -EINVAL;
351 int write;
352 size_t len;
353
354#ifdef CONFIG_MEMORY_FAILURE
355 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
356 return madvise_hwpoison(behavior, start, start+len_in);
357#endif
358 if (!madvise_behavior_valid(behavior))
359 return error;
360
361 write = madvise_need_mmap_write(behavior);
362 if (write)
363 down_write(¤t->mm->mmap_sem);
364 else
365 down_read(¤t->mm->mmap_sem);
366
367 if (start & ~PAGE_MASK)
368 goto out;
369 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
370
371 /* Check to see whether len was rounded up from small -ve to zero */
372 if (len_in && !len)
373 goto out;
374
375 end = start + len;
376 if (end < start)
377 goto out;
378
379 error = 0;
380 if (end == start)
381 goto out;
382
383 /*
384 * If the interval [start,end) covers some unmapped address
385 * ranges, just ignore them, but return -ENOMEM at the end.
386 * - different from the way of handling in mlock etc.
387 */
388 vma = find_vma_prev(current->mm, start, &prev);
389 if (vma && start > vma->vm_start)
390 prev = vma;
391
392 for (;;) {
393 /* Still start < end. */
394 error = -ENOMEM;
395 if (!vma)
396 goto out;
397
398 /* Here start < (end|vma->vm_end). */
399 if (start < vma->vm_start) {
400 unmapped_error = -ENOMEM;
401 start = vma->vm_start;
402 if (start >= end)
403 goto out;
404 }
405
406 /* Here vma->vm_start <= start < (end|vma->vm_end) */
407 tmp = vma->vm_end;
408 if (end < tmp)
409 tmp = end;
410
411 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
412 error = madvise_vma(vma, &prev, start, tmp, behavior);
413 if (error)
414 goto out;
415 start = tmp;
416 if (prev && start < prev->vm_end)
417 start = prev->vm_end;
418 error = unmapped_error;
419 if (start >= end)
420 goto out;
421 if (prev)
422 vma = prev->vm_next;
423 else /* madvise_remove dropped mmap_sem */
424 vma = find_vma(current->mm, start);
425 }
426out:
427 if (write)
428 up_write(¤t->mm->mmap_sem);
429 else
430 up_read(¤t->mm->mmap_sem);
431
432 return error;
433}