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