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Source at commit 2604e7f9a98c27be50a0c3ff7503b6a5ea8f6cfe created 12 years 7 months ago. By Maarten ter Huurne, cpufreq_stats: Support runtime changes to frequency table | |
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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 | |
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 | |
38 | /* |
39 | * We can potentially split a vm area into separate |
40 | * areas, each area with its own behavior. |
41 | */ |
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) |
45 | { |
46 | struct mm_struct * mm = vma->vm_mm; |
47 | int error = 0; |
48 | pgoff_t pgoff; |
49 | unsigned long new_flags = vma->vm_flags; |
50 | |
51 | switch (behavior) { |
52 | case MADV_NORMAL: |
53 | new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; |
54 | break; |
55 | case MADV_SEQUENTIAL: |
56 | new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ; |
57 | break; |
58 | case MADV_RANDOM: |
59 | new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ; |
60 | break; |
61 | case MADV_DONTFORK: |
62 | new_flags |= VM_DONTCOPY; |
63 | break; |
64 | case MADV_DOFORK: |
65 | if (vma->vm_flags & VM_IO) { |
66 | error = -EINVAL; |
67 | goto out; |
68 | } |
69 | new_flags &= ~VM_DONTCOPY; |
70 | break; |
71 | case MADV_DONTDUMP: |
72 | new_flags |= VM_NODUMP; |
73 | break; |
74 | case MADV_DODUMP: |
75 | new_flags &= ~VM_NODUMP; |
76 | break; |
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; |
83 | case MADV_HUGEPAGE: |
84 | case MADV_NOHUGEPAGE: |
85 | error = hugepage_madvise(vma, &new_flags, behavior); |
86 | if (error) |
87 | goto out; |
88 | break; |
89 | } |
90 | |
91 | if (new_flags == vma->vm_flags) { |
92 | *prev = vma; |
93 | goto out; |
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; |
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 | |
118 | success: |
119 | /* |
120 | * vm_flags is protected by the mmap_sem held in write mode. |
121 | */ |
122 | vma->vm_flags = new_flags; |
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, |
134 | struct vm_area_struct ** prev, |
135 | unsigned long start, unsigned long end) |
136 | { |
137 | struct file *file = vma->vm_file; |
138 | |
139 | if (!file) |
140 | return -EBADF; |
141 | |
142 | if (file->f_mapping->a_ops->get_xip_mem) { |
143 | /* no bad return value, but ignore advice */ |
144 | return 0; |
145 | } |
146 | |
147 | *prev = vma; |
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 | |
153 | force_page_cache_readahead(file->f_mapping, file, start, end - start); |
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 |
161 | * zap_page_range call sets things up for shrink_active_list to actually free |
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 |
164 | * shrink_active_list to pick up before reclaiming other pages. |
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, |
177 | struct vm_area_struct ** prev, |
178 | unsigned long start, unsigned long end) |
179 | { |
180 | *prev = vma; |
181 | if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) |
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 | |
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, |
203 | struct vm_area_struct **prev, |
204 | unsigned long start, unsigned long end) |
205 | { |
206 | loff_t offset; |
207 | int error; |
208 | struct file *f; |
209 | |
210 | *prev = NULL; /* tell sys_madvise we drop mmap_sem */ |
211 | |
212 | if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB)) |
213 | return -EINVAL; |
214 | |
215 | f = vma->vm_file; |
216 | |
217 | if (!f || !f->f_mapping || !f->f_mapping->host) { |
218 | return -EINVAL; |
219 | } |
220 | |
221 | if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE)) |
222 | return -EACCES; |
223 | |
224 | offset = (loff_t)(start - vma->vm_start) |
225 | + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
226 | |
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); |
234 | up_read(¤t->mm->mmap_sem); |
235 | error = do_fallocate(f, |
236 | FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, |
237 | offset, end - start); |
238 | fput(f); |
239 | down_read(¤t->mm->mmap_sem); |
240 | return error; |
241 | } |
242 | |
243 | #ifdef CONFIG_MEMORY_FAILURE |
244 | /* |
245 | * Error injection support for memory error handling. |
246 | */ |
247 | static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end) |
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; |
255 | int ret = get_user_pages_fast(start, 1, 0, &p); |
256 | if (ret != 1) |
257 | return ret; |
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 | } |
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 */ |
269 | memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED); |
270 | } |
271 | return ret; |
272 | } |
273 | #endif |
274 | |
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) |
278 | { |
279 | switch (behavior) { |
280 | case MADV_REMOVE: |
281 | return madvise_remove(vma, prev, start, end); |
282 | case MADV_WILLNEED: |
283 | return madvise_willneed(vma, prev, start, end); |
284 | case MADV_DONTNEED: |
285 | return madvise_dontneed(vma, prev, start, end); |
286 | default: |
287 | return madvise_behavior(vma, prev, start, end, behavior); |
288 | } |
289 | } |
290 | |
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: |
303 | #ifdef CONFIG_KSM |
304 | case MADV_MERGEABLE: |
305 | case MADV_UNMERGEABLE: |
306 | #endif |
307 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
308 | case MADV_HUGEPAGE: |
309 | case MADV_NOHUGEPAGE: |
310 | #endif |
311 | case MADV_DONTDUMP: |
312 | case MADV_DODUMP: |
313 | return 1; |
314 | |
315 | default: |
316 | return 0; |
317 | } |
318 | } |
319 | |
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. |
342 | * MADV_REMOVE - the application wants to free up the given range of |
343 | * pages and associated backing store. |
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. |
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. |
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 | */ |
362 | SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) |
363 | { |
364 | unsigned long end, tmp; |
365 | struct vm_area_struct * vma, *prev; |
366 | int unmapped_error = 0; |
367 | int error = -EINVAL; |
368 | int write; |
369 | size_t len; |
370 | |
371 | #ifdef CONFIG_MEMORY_FAILURE |
372 | if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) |
373 | return madvise_hwpoison(behavior, start, start+len_in); |
374 | #endif |
375 | if (!madvise_behavior_valid(behavior)) |
376 | return error; |
377 | |
378 | write = madvise_need_mmap_write(behavior); |
379 | if (write) |
380 | down_write(¤t->mm->mmap_sem); |
381 | else |
382 | down_read(¤t->mm->mmap_sem); |
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. |
403 | * - different from the way of handling in mlock etc. |
404 | */ |
405 | vma = find_vma_prev(current->mm, start, &prev); |
406 | if (vma && start > vma->vm_start) |
407 | prev = vma; |
408 | |
409 | for (;;) { |
410 | /* Still start < end. */ |
411 | error = -ENOMEM; |
412 | if (!vma) |
413 | goto out; |
414 | |
415 | /* Here start < (end|vma->vm_end). */ |
416 | if (start < vma->vm_start) { |
417 | unmapped_error = -ENOMEM; |
418 | start = vma->vm_start; |
419 | if (start >= end) |
420 | goto out; |
421 | } |
422 | |
423 | /* Here vma->vm_start <= start < (end|vma->vm_end) */ |
424 | tmp = vma->vm_end; |
425 | if (end < tmp) |
426 | tmp = end; |
427 | |
428 | /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ |
429 | error = madvise_vma(vma, &prev, start, tmp, behavior); |
430 | if (error) |
431 | goto out; |
432 | start = tmp; |
433 | if (prev && start < prev->vm_end) |
434 | start = prev->vm_end; |
435 | error = unmapped_error; |
436 | if (start >= end) |
437 | goto out; |
438 | if (prev) |
439 | vma = prev->vm_next; |
440 | else /* madvise_remove dropped mmap_sem */ |
441 | vma = find_vma(current->mm, start); |
442 | } |
443 | out: |
444 | if (write) |
445 | up_write(¤t->mm->mmap_sem); |
446 | else |
447 | up_read(¤t->mm->mmap_sem); |
448 | |
449 | return error; |
450 | } |
451 |
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