Commit | Line | Data |
---|---|---|
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> |
9ab4233d | 18 | #include <linux/file.h> |
1da177e4 | 19 | |
0a27a14a NP |
20 | /* |
21 | * Any behaviour which results in changes to the vma->vm_flags needs to | |
22 | * take mmap_sem for writing. Others, which simply traverse vmas, need | |
23 | * to only take it for reading. | |
24 | */ | |
25 | static int madvise_need_mmap_write(int behavior) | |
26 | { | |
27 | switch (behavior) { | |
28 | case MADV_REMOVE: | |
29 | case MADV_WILLNEED: | |
30 | case MADV_DONTNEED: | |
31 | return 0; | |
32 | default: | |
33 | /* be safe, default to 1. list exceptions explicitly */ | |
34 | return 1; | |
35 | } | |
36 | } | |
37 | ||
1da177e4 LT |
38 | /* |
39 | * We can potentially split a vm area into separate | |
40 | * areas, each area with its own behavior. | |
41 | */ | |
05b74384 PM |
42 | static long madvise_behavior(struct vm_area_struct * vma, |
43 | struct vm_area_struct **prev, | |
44 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 LT |
45 | { |
46 | struct mm_struct * mm = vma->vm_mm; | |
47 | int error = 0; | |
05b74384 | 48 | pgoff_t pgoff; |
3866ea90 | 49 | unsigned long new_flags = vma->vm_flags; |
e798c6e8 PM |
50 | |
51 | switch (behavior) { | |
f8225661 MT |
52 | case MADV_NORMAL: |
53 | new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; | |
54 | break; | |
e798c6e8 | 55 | case MADV_SEQUENTIAL: |
f8225661 | 56 | new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ; |
e798c6e8 PM |
57 | break; |
58 | case MADV_RANDOM: | |
f8225661 | 59 | new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ; |
e798c6e8 | 60 | break; |
f8225661 MT |
61 | case MADV_DONTFORK: |
62 | new_flags |= VM_DONTCOPY; | |
63 | break; | |
64 | case MADV_DOFORK: | |
3866ea90 HD |
65 | if (vma->vm_flags & VM_IO) { |
66 | error = -EINVAL; | |
67 | goto out; | |
68 | } | |
f8225661 | 69 | new_flags &= ~VM_DONTCOPY; |
e798c6e8 | 70 | break; |
accb61fe JB |
71 | case MADV_DONTDUMP: |
72 | new_flags |= VM_NODUMP; | |
73 | break; | |
74 | case MADV_DODUMP: | |
75 | new_flags &= ~VM_NODUMP; | |
76 | break; | |
f8af4da3 HD |
77 | case MADV_MERGEABLE: |
78 | case MADV_UNMERGEABLE: | |
79 | error = ksm_madvise(vma, start, end, behavior, &new_flags); | |
80 | if (error) | |
81 | goto out; | |
82 | break; | |
0af4e98b | 83 | case MADV_HUGEPAGE: |
a664b2d8 | 84 | case MADV_NOHUGEPAGE: |
60ab3244 | 85 | error = hugepage_madvise(vma, &new_flags, behavior); |
0af4e98b AA |
86 | if (error) |
87 | goto out; | |
88 | break; | |
e798c6e8 PM |
89 | } |
90 | ||
05b74384 PM |
91 | if (new_flags == vma->vm_flags) { |
92 | *prev = vma; | |
836d5ffd | 93 | goto out; |
05b74384 PM |
94 | } |
95 | ||
96 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
97 | *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma, | |
98 | vma->vm_file, pgoff, vma_policy(vma)); | |
99 | if (*prev) { | |
100 | vma = *prev; | |
101 | goto success; | |
102 | } | |
103 | ||
104 | *prev = vma; | |
1da177e4 LT |
105 | |
106 | if (start != vma->vm_start) { | |
107 | error = split_vma(mm, vma, start, 1); | |
108 | if (error) | |
109 | goto out; | |
110 | } | |
111 | ||
112 | if (end != vma->vm_end) { | |
113 | error = split_vma(mm, vma, end, 0); | |
114 | if (error) | |
115 | goto out; | |
116 | } | |
117 | ||
836d5ffd | 118 | success: |
1da177e4 LT |
119 | /* |
120 | * vm_flags is protected by the mmap_sem held in write mode. | |
121 | */ | |
e798c6e8 | 122 | vma->vm_flags = new_flags; |
1da177e4 LT |
123 | |
124 | out: | |
125 | if (error == -ENOMEM) | |
126 | error = -EAGAIN; | |
127 | return error; | |
128 | } | |
129 | ||
130 | /* | |
131 | * Schedule all required I/O operations. Do not wait for completion. | |
132 | */ | |
133 | static long madvise_willneed(struct vm_area_struct * vma, | |
05b74384 | 134 | struct vm_area_struct ** prev, |
1da177e4 LT |
135 | unsigned long start, unsigned long end) |
136 | { | |
137 | struct file *file = vma->vm_file; | |
138 | ||
1bef4003 S |
139 | if (!file) |
140 | return -EBADF; | |
141 | ||
70688e4d | 142 | if (file->f_mapping->a_ops->get_xip_mem) { |
fe77ba6f CO |
143 | /* no bad return value, but ignore advice */ |
144 | return 0; | |
145 | } | |
146 | ||
05b74384 | 147 | *prev = vma; |
1da177e4 LT |
148 | start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
149 | if (end > vma->vm_end) | |
150 | end = vma->vm_end; | |
151 | end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
152 | ||
f7e839dd | 153 | force_page_cache_readahead(file->f_mapping, file, start, end - start); |
1da177e4 LT |
154 | return 0; |
155 | } | |
156 | ||
157 | /* | |
158 | * Application no longer needs these pages. If the pages are dirty, | |
159 | * it's OK to just throw them away. The app will be more careful about | |
160 | * data it wants to keep. Be sure to free swap resources too. The | |
7e6cbea3 | 161 | * zap_page_range call sets things up for shrink_active_list to actually free |
1da177e4 LT |
162 | * these pages later if no one else has touched them in the meantime, |
163 | * although we could add these pages to a global reuse list for | |
7e6cbea3 | 164 | * shrink_active_list to pick up before reclaiming other pages. |
1da177e4 LT |
165 | * |
166 | * NB: This interface discards data rather than pushes it out to swap, | |
167 | * as some implementations do. This has performance implications for | |
168 | * applications like large transactional databases which want to discard | |
169 | * pages in anonymous maps after committing to backing store the data | |
170 | * that was kept in them. There is no reason to write this data out to | |
171 | * the swap area if the application is discarding it. | |
172 | * | |
173 | * An interface that causes the system to free clean pages and flush | |
174 | * dirty pages is already available as msync(MS_INVALIDATE). | |
175 | */ | |
176 | static long madvise_dontneed(struct vm_area_struct * vma, | |
05b74384 | 177 | struct vm_area_struct ** prev, |
1da177e4 LT |
178 | unsigned long start, unsigned long end) |
179 | { | |
05b74384 | 180 | *prev = vma; |
6aab341e | 181 | if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) |
1da177e4 LT |
182 | return -EINVAL; |
183 | ||
184 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) { | |
185 | struct zap_details details = { | |
186 | .nonlinear_vma = vma, | |
187 | .last_index = ULONG_MAX, | |
188 | }; | |
189 | zap_page_range(vma, start, end - start, &details); | |
190 | } else | |
191 | zap_page_range(vma, start, end - start, NULL); | |
192 | return 0; | |
193 | } | |
194 | ||
f6b3ec23 BP |
195 | /* |
196 | * Application wants to free up the pages and associated backing store. | |
197 | * This is effectively punching a hole into the middle of a file. | |
198 | * | |
199 | * NOTE: Currently, only shmfs/tmpfs is supported for this operation. | |
200 | * Other filesystems return -ENOSYS. | |
201 | */ | |
202 | static long madvise_remove(struct vm_area_struct *vma, | |
00e9fa2d | 203 | struct vm_area_struct **prev, |
f6b3ec23 BP |
204 | unsigned long start, unsigned long end) |
205 | { | |
3f31d075 | 206 | loff_t offset; |
90ed52eb | 207 | int error; |
9ab4233d | 208 | struct file *f; |
f6b3ec23 | 209 | |
90ed52eb | 210 | *prev = NULL; /* tell sys_madvise we drop mmap_sem */ |
00e9fa2d | 211 | |
f6b3ec23 BP |
212 | if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB)) |
213 | return -EINVAL; | |
214 | ||
9ab4233d AL |
215 | f = vma->vm_file; |
216 | ||
217 | if (!f || !f->f_mapping || !f->f_mapping->host) { | |
f6b3ec23 BP |
218 | return -EINVAL; |
219 | } | |
220 | ||
69cf0fac HD |
221 | if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE)) |
222 | return -EACCES; | |
223 | ||
f6b3ec23 BP |
224 | offset = (loff_t)(start - vma->vm_start) |
225 | + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); | |
90ed52eb | 226 | |
9ab4233d AL |
227 | /* |
228 | * Filesystem's fallocate may need to take i_mutex. We need to | |
229 | * explicitly grab a reference because the vma (and hence the | |
230 | * vma's reference to the file) can go away as soon as we drop | |
231 | * mmap_sem. | |
232 | */ | |
233 | get_file(f); | |
0a27a14a | 234 | up_read(¤t->mm->mmap_sem); |
9ab4233d | 235 | error = do_fallocate(f, |
3f31d075 HD |
236 | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, |
237 | offset, end - start); | |
9ab4233d | 238 | fput(f); |
0a27a14a | 239 | down_read(¤t->mm->mmap_sem); |
90ed52eb | 240 | return error; |
f6b3ec23 BP |
241 | } |
242 | ||
9893e49d AK |
243 | #ifdef CONFIG_MEMORY_FAILURE |
244 | /* | |
245 | * Error injection support for memory error handling. | |
246 | */ | |
afcf938e | 247 | static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end) |
9893e49d AK |
248 | { |
249 | int ret = 0; | |
250 | ||
251 | if (!capable(CAP_SYS_ADMIN)) | |
252 | return -EPERM; | |
253 | for (; start < end; start += PAGE_SIZE) { | |
254 | struct page *p; | |
d15f107d | 255 | int ret = get_user_pages_fast(start, 1, 0, &p); |
9893e49d AK |
256 | if (ret != 1) |
257 | return ret; | |
afcf938e AK |
258 | if (bhv == MADV_SOFT_OFFLINE) { |
259 | printk(KERN_INFO "Soft offlining page %lx at %lx\n", | |
260 | page_to_pfn(p), start); | |
261 | ret = soft_offline_page(p, MF_COUNT_INCREASED); | |
262 | if (ret) | |
263 | break; | |
264 | continue; | |
265 | } | |
9893e49d AK |
266 | printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n", |
267 | page_to_pfn(p), start); | |
268 | /* Ignore return value for now */ | |
cd42f4a3 | 269 | memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED); |
9893e49d AK |
270 | } |
271 | return ret; | |
272 | } | |
273 | #endif | |
274 | ||
165cd402 | 275 | static long |
276 | madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, | |
277 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 | 278 | { |
1da177e4 | 279 | switch (behavior) { |
f6b3ec23 | 280 | case MADV_REMOVE: |
3866ea90 | 281 | return madvise_remove(vma, prev, start, end); |
1da177e4 | 282 | case MADV_WILLNEED: |
3866ea90 | 283 | return madvise_willneed(vma, prev, start, end); |
1da177e4 | 284 | case MADV_DONTNEED: |
3866ea90 | 285 | return madvise_dontneed(vma, prev, start, end); |
1da177e4 | 286 | default: |
3866ea90 | 287 | return madvise_behavior(vma, prev, start, end, behavior); |
1da177e4 | 288 | } |
1da177e4 LT |
289 | } |
290 | ||
75927af8 NP |
291 | static int |
292 | madvise_behavior_valid(int behavior) | |
293 | { | |
294 | switch (behavior) { | |
295 | case MADV_DOFORK: | |
296 | case MADV_DONTFORK: | |
297 | case MADV_NORMAL: | |
298 | case MADV_SEQUENTIAL: | |
299 | case MADV_RANDOM: | |
300 | case MADV_REMOVE: | |
301 | case MADV_WILLNEED: | |
302 | case MADV_DONTNEED: | |
f8af4da3 HD |
303 | #ifdef CONFIG_KSM |
304 | case MADV_MERGEABLE: | |
305 | case MADV_UNMERGEABLE: | |
0af4e98b AA |
306 | #endif |
307 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE | |
308 | case MADV_HUGEPAGE: | |
a664b2d8 | 309 | case MADV_NOHUGEPAGE: |
f8af4da3 | 310 | #endif |
accb61fe JB |
311 | case MADV_DONTDUMP: |
312 | case MADV_DODUMP: | |
75927af8 NP |
313 | return 1; |
314 | ||
315 | default: | |
316 | return 0; | |
317 | } | |
318 | } | |
3866ea90 | 319 | |
1da177e4 LT |
320 | /* |
321 | * The madvise(2) system call. | |
322 | * | |
323 | * Applications can use madvise() to advise the kernel how it should | |
324 | * handle paging I/O in this VM area. The idea is to help the kernel | |
325 | * use appropriate read-ahead and caching techniques. The information | |
326 | * provided is advisory only, and can be safely disregarded by the | |
327 | * kernel without affecting the correct operation of the application. | |
328 | * | |
329 | * behavior values: | |
330 | * MADV_NORMAL - the default behavior is to read clusters. This | |
331 | * results in some read-ahead and read-behind. | |
332 | * MADV_RANDOM - the system should read the minimum amount of data | |
333 | * on any access, since it is unlikely that the appli- | |
334 | * cation will need more than what it asks for. | |
335 | * MADV_SEQUENTIAL - pages in the given range will probably be accessed | |
336 | * once, so they can be aggressively read ahead, and | |
337 | * can be freed soon after they are accessed. | |
338 | * MADV_WILLNEED - the application is notifying the system to read | |
339 | * some pages ahead. | |
340 | * MADV_DONTNEED - the application is finished with the given range, | |
341 | * so the kernel can free resources associated with it. | |
f6b3ec23 BP |
342 | * MADV_REMOVE - the application wants to free up the given range of |
343 | * pages and associated backing store. | |
3866ea90 HD |
344 | * MADV_DONTFORK - omit this area from child's address space when forking: |
345 | * typically, to avoid COWing pages pinned by get_user_pages(). | |
346 | * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking. | |
f8af4da3 HD |
347 | * MADV_MERGEABLE - the application recommends that KSM try to merge pages in |
348 | * this area with pages of identical content from other such areas. | |
349 | * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others. | |
1da177e4 LT |
350 | * |
351 | * return values: | |
352 | * zero - success | |
353 | * -EINVAL - start + len < 0, start is not page-aligned, | |
354 | * "behavior" is not a valid value, or application | |
355 | * is attempting to release locked or shared pages. | |
356 | * -ENOMEM - addresses in the specified range are not currently | |
357 | * mapped, or are outside the AS of the process. | |
358 | * -EIO - an I/O error occurred while paging in data. | |
359 | * -EBADF - map exists, but area maps something that isn't a file. | |
360 | * -EAGAIN - a kernel resource was temporarily unavailable. | |
361 | */ | |
3480b257 | 362 | SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) |
1da177e4 | 363 | { |
05b74384 PM |
364 | unsigned long end, tmp; |
365 | struct vm_area_struct * vma, *prev; | |
1da177e4 LT |
366 | int unmapped_error = 0; |
367 | int error = -EINVAL; | |
f7977793 | 368 | int write; |
1da177e4 LT |
369 | size_t len; |
370 | ||
9893e49d | 371 | #ifdef CONFIG_MEMORY_FAILURE |
afcf938e AK |
372 | if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) |
373 | return madvise_hwpoison(behavior, start, start+len_in); | |
9893e49d | 374 | #endif |
75927af8 NP |
375 | if (!madvise_behavior_valid(behavior)) |
376 | return error; | |
377 | ||
f7977793 JB |
378 | write = madvise_need_mmap_write(behavior); |
379 | if (write) | |
0a27a14a NP |
380 | down_write(¤t->mm->mmap_sem); |
381 | else | |
382 | down_read(¤t->mm->mmap_sem); | |
1da177e4 LT |
383 | |
384 | if (start & ~PAGE_MASK) | |
385 | goto out; | |
386 | len = (len_in + ~PAGE_MASK) & PAGE_MASK; | |
387 | ||
388 | /* Check to see whether len was rounded up from small -ve to zero */ | |
389 | if (len_in && !len) | |
390 | goto out; | |
391 | ||
392 | end = start + len; | |
393 | if (end < start) | |
394 | goto out; | |
395 | ||
396 | error = 0; | |
397 | if (end == start) | |
398 | goto out; | |
399 | ||
400 | /* | |
401 | * If the interval [start,end) covers some unmapped address | |
402 | * ranges, just ignore them, but return -ENOMEM at the end. | |
05b74384 | 403 | * - different from the way of handling in mlock etc. |
1da177e4 | 404 | */ |
05b74384 | 405 | vma = find_vma_prev(current->mm, start, &prev); |
836d5ffd HD |
406 | if (vma && start > vma->vm_start) |
407 | prev = vma; | |
408 | ||
1da177e4 LT |
409 | for (;;) { |
410 | /* Still start < end. */ | |
411 | error = -ENOMEM; | |
412 | if (!vma) | |
413 | goto out; | |
414 | ||
05b74384 | 415 | /* Here start < (end|vma->vm_end). */ |
1da177e4 LT |
416 | if (start < vma->vm_start) { |
417 | unmapped_error = -ENOMEM; | |
418 | start = vma->vm_start; | |
05b74384 PM |
419 | if (start >= end) |
420 | goto out; | |
1da177e4 LT |
421 | } |
422 | ||
05b74384 PM |
423 | /* Here vma->vm_start <= start < (end|vma->vm_end) */ |
424 | tmp = vma->vm_end; | |
425 | if (end < tmp) | |
426 | tmp = end; | |
1da177e4 | 427 | |
05b74384 PM |
428 | /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ |
429 | error = madvise_vma(vma, &prev, start, tmp, behavior); | |
1da177e4 LT |
430 | if (error) |
431 | goto out; | |
05b74384 | 432 | start = tmp; |
90ed52eb | 433 | if (prev && start < prev->vm_end) |
05b74384 PM |
434 | start = prev->vm_end; |
435 | error = unmapped_error; | |
436 | if (start >= end) | |
437 | goto out; | |
90ed52eb HD |
438 | if (prev) |
439 | vma = prev->vm_next; | |
440 | else /* madvise_remove dropped mmap_sem */ | |
441 | vma = find_vma(current->mm, start); | |
1da177e4 | 442 | } |
1da177e4 | 443 | out: |
f7977793 | 444 | if (write) |
0a27a14a NP |
445 | up_write(¤t->mm->mmap_sem); |
446 | else | |
447 | up_read(¤t->mm->mmap_sem); | |
448 | ||
1da177e4 LT |
449 | return error; |
450 | } |