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Commit | Line | Data |
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1da177e4 LT |
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> | |
05b74384 | 11 | #include <linux/mempolicy.h> |
afcf938e | 12 | #include <linux/page-isolation.h> |
1da177e4 | 13 | #include <linux/hugetlb.h> |
3f31d075 | 14 | #include <linux/falloc.h> |
e8edc6e0 | 15 | #include <linux/sched.h> |
f8af4da3 | 16 | #include <linux/ksm.h> |
3f31d075 | 17 | #include <linux/fs.h> |
1da177e4 | 18 | |
0a27a14a NP |
19 | /* |
20 | * Any behaviour which results in changes to the vma->vm_flags needs to | |
21 | * take mmap_sem for writing. Others, which simply traverse vmas, need | |
22 | * to only take it for reading. | |
23 | */ | |
24 | static int madvise_need_mmap_write(int behavior) | |
25 | { | |
26 | switch (behavior) { | |
27 | case MADV_REMOVE: | |
28 | case MADV_WILLNEED: | |
29 | case MADV_DONTNEED: | |
30 | return 0; | |
31 | default: | |
32 | /* be safe, default to 1. list exceptions explicitly */ | |
33 | return 1; | |
34 | } | |
35 | } | |
36 | ||
1da177e4 LT |
37 | /* |
38 | * We can potentially split a vm area into separate | |
39 | * areas, each area with its own behavior. | |
40 | */ | |
05b74384 PM |
41 | static long madvise_behavior(struct vm_area_struct * vma, |
42 | struct vm_area_struct **prev, | |
43 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 LT |
44 | { |
45 | struct mm_struct * mm = vma->vm_mm; | |
46 | int error = 0; | |
05b74384 | 47 | pgoff_t pgoff; |
3866ea90 | 48 | unsigned long new_flags = vma->vm_flags; |
e798c6e8 PM |
49 | |
50 | switch (behavior) { | |
f8225661 MT |
51 | case MADV_NORMAL: |
52 | new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; | |
53 | break; | |
e798c6e8 | 54 | case MADV_SEQUENTIAL: |
f8225661 | 55 | new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ; |
e798c6e8 PM |
56 | break; |
57 | case MADV_RANDOM: | |
f8225661 | 58 | new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ; |
e798c6e8 | 59 | break; |
f8225661 MT |
60 | case MADV_DONTFORK: |
61 | new_flags |= VM_DONTCOPY; | |
62 | break; | |
63 | case MADV_DOFORK: | |
3866ea90 HD |
64 | if (vma->vm_flags & VM_IO) { |
65 | error = -EINVAL; | |
66 | goto out; | |
67 | } | |
f8225661 | 68 | new_flags &= ~VM_DONTCOPY; |
e798c6e8 | 69 | break; |
accb61fe JB |
70 | case MADV_DONTDUMP: |
71 | new_flags |= VM_NODUMP; | |
72 | break; | |
73 | case MADV_DODUMP: | |
74 | new_flags &= ~VM_NODUMP; | |
75 | break; | |
f8af4da3 HD |
76 | case MADV_MERGEABLE: |
77 | case MADV_UNMERGEABLE: | |
78 | error = ksm_madvise(vma, start, end, behavior, &new_flags); | |
79 | if (error) | |
80 | goto out; | |
81 | break; | |
0af4e98b | 82 | case MADV_HUGEPAGE: |
a664b2d8 | 83 | case MADV_NOHUGEPAGE: |
60ab3244 | 84 | error = hugepage_madvise(vma, &new_flags, behavior); |
0af4e98b AA |
85 | if (error) |
86 | goto out; | |
87 | break; | |
e798c6e8 PM |
88 | } |
89 | ||
05b74384 PM |
90 | if (new_flags == vma->vm_flags) { |
91 | *prev = vma; | |
836d5ffd | 92 | goto out; |
05b74384 PM |
93 | } |
94 | ||
95 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
96 | *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma, | |
97 | vma->vm_file, pgoff, vma_policy(vma)); | |
98 | if (*prev) { | |
99 | vma = *prev; | |
100 | goto success; | |
101 | } | |
102 | ||
103 | *prev = vma; | |
1da177e4 LT |
104 | |
105 | if (start != vma->vm_start) { | |
106 | error = split_vma(mm, vma, start, 1); | |
107 | if (error) | |
108 | goto out; | |
109 | } | |
110 | ||
111 | if (end != vma->vm_end) { | |
112 | error = split_vma(mm, vma, end, 0); | |
113 | if (error) | |
114 | goto out; | |
115 | } | |
116 | ||
836d5ffd | 117 | success: |
1da177e4 LT |
118 | /* |
119 | * vm_flags is protected by the mmap_sem held in write mode. | |
120 | */ | |
e798c6e8 | 121 | vma->vm_flags = new_flags; |
1da177e4 LT |
122 | |
123 | out: | |
124 | if (error == -ENOMEM) | |
125 | error = -EAGAIN; | |
126 | return error; | |
127 | } | |
128 | ||
129 | /* | |
130 | * Schedule all required I/O operations. Do not wait for completion. | |
131 | */ | |
132 | static long madvise_willneed(struct vm_area_struct * vma, | |
05b74384 | 133 | struct vm_area_struct ** prev, |
1da177e4 LT |
134 | unsigned long start, unsigned long end) |
135 | { | |
136 | struct file *file = vma->vm_file; | |
137 | ||
1bef4003 S |
138 | if (!file) |
139 | return -EBADF; | |
140 | ||
70688e4d | 141 | if (file->f_mapping->a_ops->get_xip_mem) { |
fe77ba6f CO |
142 | /* no bad return value, but ignore advice */ |
143 | return 0; | |
144 | } | |
145 | ||
05b74384 | 146 | *prev = vma; |
1da177e4 LT |
147 | start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
148 | if (end > vma->vm_end) | |
149 | end = vma->vm_end; | |
150 | end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
151 | ||
f7e839dd | 152 | force_page_cache_readahead(file->f_mapping, file, start, end - start); |
1da177e4 LT |
153 | return 0; |
154 | } | |
155 | ||
156 | /* | |
157 | * Application no longer needs these pages. If the pages are dirty, | |
158 | * it's OK to just throw them away. The app will be more careful about | |
159 | * data it wants to keep. Be sure to free swap resources too. The | |
7e6cbea3 | 160 | * zap_page_range call sets things up for shrink_active_list to actually free |
1da177e4 LT |
161 | * these pages later if no one else has touched them in the meantime, |
162 | * although we could add these pages to a global reuse list for | |
7e6cbea3 | 163 | * shrink_active_list to pick up before reclaiming other pages. |
1da177e4 LT |
164 | * |
165 | * NB: This interface discards data rather than pushes it out to swap, | |
166 | * as some implementations do. This has performance implications for | |
167 | * applications like large transactional databases which want to discard | |
168 | * pages in anonymous maps after committing to backing store the data | |
169 | * that was kept in them. There is no reason to write this data out to | |
170 | * the swap area if the application is discarding it. | |
171 | * | |
172 | * An interface that causes the system to free clean pages and flush | |
173 | * dirty pages is already available as msync(MS_INVALIDATE). | |
174 | */ | |
175 | static long madvise_dontneed(struct vm_area_struct * vma, | |
05b74384 | 176 | struct vm_area_struct ** prev, |
1da177e4 LT |
177 | unsigned long start, unsigned long end) |
178 | { | |
05b74384 | 179 | *prev = vma; |
6aab341e | 180 | if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) |
1da177e4 LT |
181 | return -EINVAL; |
182 | ||
183 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) { | |
184 | struct zap_details details = { | |
185 | .nonlinear_vma = vma, | |
186 | .last_index = ULONG_MAX, | |
187 | }; | |
188 | zap_page_range(vma, start, end - start, &details); | |
189 | } else | |
190 | zap_page_range(vma, start, end - start, NULL); | |
191 | return 0; | |
192 | } | |
193 | ||
f6b3ec23 BP |
194 | /* |
195 | * Application wants to free up the pages and associated backing store. | |
196 | * This is effectively punching a hole into the middle of a file. | |
197 | * | |
198 | * NOTE: Currently, only shmfs/tmpfs is supported for this operation. | |
199 | * Other filesystems return -ENOSYS. | |
200 | */ | |
201 | static long madvise_remove(struct vm_area_struct *vma, | |
00e9fa2d | 202 | struct vm_area_struct **prev, |
f6b3ec23 BP |
203 | unsigned long start, unsigned long end) |
204 | { | |
3f31d075 | 205 | loff_t offset; |
90ed52eb | 206 | int error; |
f6b3ec23 | 207 | |
90ed52eb | 208 | *prev = NULL; /* tell sys_madvise we drop mmap_sem */ |
00e9fa2d | 209 | |
f6b3ec23 BP |
210 | if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB)) |
211 | return -EINVAL; | |
212 | ||
213 | if (!vma->vm_file || !vma->vm_file->f_mapping | |
214 | || !vma->vm_file->f_mapping->host) { | |
215 | return -EINVAL; | |
216 | } | |
217 | ||
69cf0fac HD |
218 | if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE)) |
219 | return -EACCES; | |
220 | ||
f6b3ec23 BP |
221 | offset = (loff_t)(start - vma->vm_start) |
222 | + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); | |
90ed52eb | 223 | |
3f31d075 | 224 | /* filesystem's fallocate may need to take i_mutex */ |
0a27a14a | 225 | up_read(¤t->mm->mmap_sem); |
3f31d075 HD |
226 | error = do_fallocate(vma->vm_file, |
227 | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, | |
228 | offset, end - start); | |
0a27a14a | 229 | down_read(¤t->mm->mmap_sem); |
90ed52eb | 230 | return error; |
f6b3ec23 BP |
231 | } |
232 | ||
9893e49d AK |
233 | #ifdef CONFIG_MEMORY_FAILURE |
234 | /* | |
235 | * Error injection support for memory error handling. | |
236 | */ | |
afcf938e | 237 | static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end) |
9893e49d AK |
238 | { |
239 | int ret = 0; | |
240 | ||
241 | if (!capable(CAP_SYS_ADMIN)) | |
242 | return -EPERM; | |
243 | for (; start < end; start += PAGE_SIZE) { | |
244 | struct page *p; | |
d15f107d | 245 | int ret = get_user_pages_fast(start, 1, 0, &p); |
9893e49d AK |
246 | if (ret != 1) |
247 | return ret; | |
afcf938e AK |
248 | if (bhv == MADV_SOFT_OFFLINE) { |
249 | printk(KERN_INFO "Soft offlining page %lx at %lx\n", | |
250 | page_to_pfn(p), start); | |
251 | ret = soft_offline_page(p, MF_COUNT_INCREASED); | |
252 | if (ret) | |
253 | break; | |
254 | continue; | |
255 | } | |
9893e49d AK |
256 | printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n", |
257 | page_to_pfn(p), start); | |
258 | /* Ignore return value for now */ | |
cd42f4a3 | 259 | memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED); |
9893e49d AK |
260 | } |
261 | return ret; | |
262 | } | |
263 | #endif | |
264 | ||
165cd402 | 265 | static long |
266 | madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, | |
267 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 | 268 | { |
1da177e4 | 269 | switch (behavior) { |
f6b3ec23 | 270 | case MADV_REMOVE: |
3866ea90 | 271 | return madvise_remove(vma, prev, start, end); |
1da177e4 | 272 | case MADV_WILLNEED: |
3866ea90 | 273 | return madvise_willneed(vma, prev, start, end); |
1da177e4 | 274 | case MADV_DONTNEED: |
3866ea90 | 275 | return madvise_dontneed(vma, prev, start, end); |
1da177e4 | 276 | default: |
3866ea90 | 277 | return madvise_behavior(vma, prev, start, end, behavior); |
1da177e4 | 278 | } |
1da177e4 LT |
279 | } |
280 | ||
75927af8 NP |
281 | static int |
282 | madvise_behavior_valid(int behavior) | |
283 | { | |
284 | switch (behavior) { | |
285 | case MADV_DOFORK: | |
286 | case MADV_DONTFORK: | |
287 | case MADV_NORMAL: | |
288 | case MADV_SEQUENTIAL: | |
289 | case MADV_RANDOM: | |
290 | case MADV_REMOVE: | |
291 | case MADV_WILLNEED: | |
292 | case MADV_DONTNEED: | |
f8af4da3 HD |
293 | #ifdef CONFIG_KSM |
294 | case MADV_MERGEABLE: | |
295 | case MADV_UNMERGEABLE: | |
0af4e98b AA |
296 | #endif |
297 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
298 | case MADV_HUGEPAGE: | |
a664b2d8 | 299 | case MADV_NOHUGEPAGE: |
f8af4da3 | 300 | #endif |
accb61fe JB |
301 | case MADV_DONTDUMP: |
302 | case MADV_DODUMP: | |
75927af8 NP |
303 | return 1; |
304 | ||
305 | default: | |
306 | return 0; | |
307 | } | |
308 | } | |
3866ea90 | 309 | |
1da177e4 LT |
310 | /* |
311 | * The madvise(2) system call. | |
312 | * | |
313 | * Applications can use madvise() to advise the kernel how it should | |
314 | * handle paging I/O in this VM area. The idea is to help the kernel | |
315 | * use appropriate read-ahead and caching techniques. The information | |
316 | * provided is advisory only, and can be safely disregarded by the | |
317 | * kernel without affecting the correct operation of the application. | |
318 | * | |
319 | * behavior values: | |
320 | * MADV_NORMAL - the default behavior is to read clusters. This | |
321 | * results in some read-ahead and read-behind. | |
322 | * MADV_RANDOM - the system should read the minimum amount of data | |
323 | * on any access, since it is unlikely that the appli- | |
324 | * cation will need more than what it asks for. | |
325 | * MADV_SEQUENTIAL - pages in the given range will probably be accessed | |
326 | * once, so they can be aggressively read ahead, and | |
327 | * can be freed soon after they are accessed. | |
328 | * MADV_WILLNEED - the application is notifying the system to read | |
329 | * some pages ahead. | |
330 | * MADV_DONTNEED - the application is finished with the given range, | |
331 | * so the kernel can free resources associated with it. | |
f6b3ec23 BP |
332 | * MADV_REMOVE - the application wants to free up the given range of |
333 | * pages and associated backing store. | |
3866ea90 HD |
334 | * MADV_DONTFORK - omit this area from child's address space when forking: |
335 | * typically, to avoid COWing pages pinned by get_user_pages(). | |
336 | * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking. | |
f8af4da3 HD |
337 | * MADV_MERGEABLE - the application recommends that KSM try to merge pages in |
338 | * this area with pages of identical content from other such areas. | |
339 | * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others. | |
1da177e4 LT |
340 | * |
341 | * return values: | |
342 | * zero - success | |
343 | * -EINVAL - start + len < 0, start is not page-aligned, | |
344 | * "behavior" is not a valid value, or application | |
345 | * is attempting to release locked or shared pages. | |
346 | * -ENOMEM - addresses in the specified range are not currently | |
347 | * mapped, or are outside the AS of the process. | |
348 | * -EIO - an I/O error occurred while paging in data. | |
349 | * -EBADF - map exists, but area maps something that isn't a file. | |
350 | * -EAGAIN - a kernel resource was temporarily unavailable. | |
351 | */ | |
3480b257 | 352 | SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) |
1da177e4 | 353 | { |
05b74384 PM |
354 | unsigned long end, tmp; |
355 | struct vm_area_struct * vma, *prev; | |
1da177e4 LT |
356 | int unmapped_error = 0; |
357 | int error = -EINVAL; | |
f7977793 | 358 | int write; |
1da177e4 LT |
359 | size_t len; |
360 | ||
9893e49d | 361 | #ifdef CONFIG_MEMORY_FAILURE |
afcf938e AK |
362 | if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) |
363 | return madvise_hwpoison(behavior, start, start+len_in); | |
9893e49d | 364 | #endif |
75927af8 NP |
365 | if (!madvise_behavior_valid(behavior)) |
366 | return error; | |
367 | ||
f7977793 JB |
368 | write = madvise_need_mmap_write(behavior); |
369 | if (write) | |
0a27a14a NP |
370 | down_write(¤t->mm->mmap_sem); |
371 | else | |
372 | down_read(¤t->mm->mmap_sem); | |
1da177e4 LT |
373 | |
374 | if (start & ~PAGE_MASK) | |
375 | goto out; | |
376 | len = (len_in + ~PAGE_MASK) & PAGE_MASK; | |
377 | ||
378 | /* Check to see whether len was rounded up from small -ve to zero */ | |
379 | if (len_in && !len) | |
380 | goto out; | |
381 | ||
382 | end = start + len; | |
383 | if (end < start) | |
384 | goto out; | |
385 | ||
386 | error = 0; | |
387 | if (end == start) | |
388 | goto out; | |
389 | ||
390 | /* | |
391 | * If the interval [start,end) covers some unmapped address | |
392 | * ranges, just ignore them, but return -ENOMEM at the end. | |
05b74384 | 393 | * - different from the way of handling in mlock etc. |
1da177e4 | 394 | */ |
05b74384 | 395 | vma = find_vma_prev(current->mm, start, &prev); |
836d5ffd HD |
396 | if (vma && start > vma->vm_start) |
397 | prev = vma; | |
398 | ||
1da177e4 LT |
399 | for (;;) { |
400 | /* Still start < end. */ | |
401 | error = -ENOMEM; | |
402 | if (!vma) | |
403 | goto out; | |
404 | ||
05b74384 | 405 | /* Here start < (end|vma->vm_end). */ |
1da177e4 LT |
406 | if (start < vma->vm_start) { |
407 | unmapped_error = -ENOMEM; | |
408 | start = vma->vm_start; | |
05b74384 PM |
409 | if (start >= end) |
410 | goto out; | |
1da177e4 LT |
411 | } |
412 | ||
05b74384 PM |
413 | /* Here vma->vm_start <= start < (end|vma->vm_end) */ |
414 | tmp = vma->vm_end; | |
415 | if (end < tmp) | |
416 | tmp = end; | |
1da177e4 | 417 | |
05b74384 PM |
418 | /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ |
419 | error = madvise_vma(vma, &prev, start, tmp, behavior); | |
1da177e4 LT |
420 | if (error) |
421 | goto out; | |
05b74384 | 422 | start = tmp; |
90ed52eb | 423 | if (prev && start < prev->vm_end) |
05b74384 PM |
424 | start = prev->vm_end; |
425 | error = unmapped_error; | |
426 | if (start >= end) | |
427 | goto out; | |
90ed52eb HD |
428 | if (prev) |
429 | vma = prev->vm_next; | |
430 | else /* madvise_remove dropped mmap_sem */ | |
431 | vma = find_vma(current->mm, start); | |
1da177e4 | 432 | } |
1da177e4 | 433 | out: |
f7977793 | 434 | if (write) |
0a27a14a NP |
435 | up_write(¤t->mm->mmap_sem); |
436 | else | |
437 | up_read(¤t->mm->mmap_sem); | |
438 | ||
1da177e4 LT |
439 | return error; |
440 | } |