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> |
1da177e4 LT |
12 | #include <linux/hugetlb.h> |
13 | ||
14 | /* | |
15 | * We can potentially split a vm area into separate | |
16 | * areas, each area with its own behavior. | |
17 | */ | |
05b74384 PM |
18 | static long madvise_behavior(struct vm_area_struct * vma, |
19 | struct vm_area_struct **prev, | |
20 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 LT |
21 | { |
22 | struct mm_struct * mm = vma->vm_mm; | |
23 | int error = 0; | |
05b74384 | 24 | pgoff_t pgoff; |
e798c6e8 PM |
25 | int new_flags = vma->vm_flags & ~VM_READHINTMASK; |
26 | ||
27 | switch (behavior) { | |
28 | case MADV_SEQUENTIAL: | |
29 | new_flags |= VM_SEQ_READ; | |
30 | break; | |
31 | case MADV_RANDOM: | |
32 | new_flags |= VM_RAND_READ; | |
33 | break; | |
34 | default: | |
35 | break; | |
36 | } | |
37 | ||
05b74384 PM |
38 | if (new_flags == vma->vm_flags) { |
39 | *prev = vma; | |
40 | goto success; | |
41 | } | |
42 | ||
43 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
44 | *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma, | |
45 | vma->vm_file, pgoff, vma_policy(vma)); | |
46 | if (*prev) { | |
47 | vma = *prev; | |
48 | goto success; | |
49 | } | |
50 | ||
51 | *prev = vma; | |
1da177e4 LT |
52 | |
53 | if (start != vma->vm_start) { | |
54 | error = split_vma(mm, vma, start, 1); | |
55 | if (error) | |
56 | goto out; | |
57 | } | |
58 | ||
59 | if (end != vma->vm_end) { | |
60 | error = split_vma(mm, vma, end, 0); | |
61 | if (error) | |
62 | goto out; | |
63 | } | |
64 | ||
65 | /* | |
66 | * vm_flags is protected by the mmap_sem held in write mode. | |
67 | */ | |
e798c6e8 | 68 | vma->vm_flags = new_flags; |
1da177e4 LT |
69 | |
70 | out: | |
71 | if (error == -ENOMEM) | |
72 | error = -EAGAIN; | |
05b74384 | 73 | success: |
1da177e4 LT |
74 | return error; |
75 | } | |
76 | ||
77 | /* | |
78 | * Schedule all required I/O operations. Do not wait for completion. | |
79 | */ | |
80 | static long madvise_willneed(struct vm_area_struct * vma, | |
05b74384 | 81 | struct vm_area_struct ** prev, |
1da177e4 LT |
82 | unsigned long start, unsigned long end) |
83 | { | |
84 | struct file *file = vma->vm_file; | |
85 | ||
86 | if (!file) | |
87 | return -EBADF; | |
88 | ||
fe77ba6f CO |
89 | if (file->f_mapping->a_ops->get_xip_page) { |
90 | /* no bad return value, but ignore advice */ | |
91 | return 0; | |
92 | } | |
93 | ||
05b74384 | 94 | *prev = vma; |
1da177e4 LT |
95 | start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
96 | if (end > vma->vm_end) | |
97 | end = vma->vm_end; | |
98 | end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
99 | ||
100 | force_page_cache_readahead(file->f_mapping, | |
101 | file, start, max_sane_readahead(end - start)); | |
102 | return 0; | |
103 | } | |
104 | ||
105 | /* | |
106 | * Application no longer needs these pages. If the pages are dirty, | |
107 | * it's OK to just throw them away. The app will be more careful about | |
108 | * data it wants to keep. Be sure to free swap resources too. The | |
109 | * zap_page_range call sets things up for refill_inactive to actually free | |
110 | * these pages later if no one else has touched them in the meantime, | |
111 | * although we could add these pages to a global reuse list for | |
112 | * refill_inactive to pick up before reclaiming other pages. | |
113 | * | |
114 | * NB: This interface discards data rather than pushes it out to swap, | |
115 | * as some implementations do. This has performance implications for | |
116 | * applications like large transactional databases which want to discard | |
117 | * pages in anonymous maps after committing to backing store the data | |
118 | * that was kept in them. There is no reason to write this data out to | |
119 | * the swap area if the application is discarding it. | |
120 | * | |
121 | * An interface that causes the system to free clean pages and flush | |
122 | * dirty pages is already available as msync(MS_INVALIDATE). | |
123 | */ | |
124 | static long madvise_dontneed(struct vm_area_struct * vma, | |
05b74384 | 125 | struct vm_area_struct ** prev, |
1da177e4 LT |
126 | unsigned long start, unsigned long end) |
127 | { | |
05b74384 | 128 | *prev = vma; |
1da177e4 LT |
129 | if ((vma->vm_flags & VM_LOCKED) || is_vm_hugetlb_page(vma)) |
130 | return -EINVAL; | |
131 | ||
132 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) { | |
133 | struct zap_details details = { | |
134 | .nonlinear_vma = vma, | |
135 | .last_index = ULONG_MAX, | |
136 | }; | |
137 | zap_page_range(vma, start, end - start, &details); | |
138 | } else | |
139 | zap_page_range(vma, start, end - start, NULL); | |
140 | return 0; | |
141 | } | |
142 | ||
05b74384 PM |
143 | static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, |
144 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 LT |
145 | { |
146 | long error = -EBADF; | |
147 | ||
148 | switch (behavior) { | |
149 | case MADV_NORMAL: | |
150 | case MADV_SEQUENTIAL: | |
151 | case MADV_RANDOM: | |
05b74384 | 152 | error = madvise_behavior(vma, prev, start, end, behavior); |
1da177e4 LT |
153 | break; |
154 | ||
155 | case MADV_WILLNEED: | |
05b74384 | 156 | error = madvise_willneed(vma, prev, start, end); |
1da177e4 LT |
157 | break; |
158 | ||
159 | case MADV_DONTNEED: | |
05b74384 | 160 | error = madvise_dontneed(vma, prev, start, end); |
1da177e4 LT |
161 | break; |
162 | ||
163 | default: | |
164 | error = -EINVAL; | |
165 | break; | |
166 | } | |
167 | ||
168 | return error; | |
169 | } | |
170 | ||
171 | /* | |
172 | * The madvise(2) system call. | |
173 | * | |
174 | * Applications can use madvise() to advise the kernel how it should | |
175 | * handle paging I/O in this VM area. The idea is to help the kernel | |
176 | * use appropriate read-ahead and caching techniques. The information | |
177 | * provided is advisory only, and can be safely disregarded by the | |
178 | * kernel without affecting the correct operation of the application. | |
179 | * | |
180 | * behavior values: | |
181 | * MADV_NORMAL - the default behavior is to read clusters. This | |
182 | * results in some read-ahead and read-behind. | |
183 | * MADV_RANDOM - the system should read the minimum amount of data | |
184 | * on any access, since it is unlikely that the appli- | |
185 | * cation will need more than what it asks for. | |
186 | * MADV_SEQUENTIAL - pages in the given range will probably be accessed | |
187 | * once, so they can be aggressively read ahead, and | |
188 | * can be freed soon after they are accessed. | |
189 | * MADV_WILLNEED - the application is notifying the system to read | |
190 | * some pages ahead. | |
191 | * MADV_DONTNEED - the application is finished with the given range, | |
192 | * so the kernel can free resources associated with it. | |
193 | * | |
194 | * return values: | |
195 | * zero - success | |
196 | * -EINVAL - start + len < 0, start is not page-aligned, | |
197 | * "behavior" is not a valid value, or application | |
198 | * is attempting to release locked or shared pages. | |
199 | * -ENOMEM - addresses in the specified range are not currently | |
200 | * mapped, or are outside the AS of the process. | |
201 | * -EIO - an I/O error occurred while paging in data. | |
202 | * -EBADF - map exists, but area maps something that isn't a file. | |
203 | * -EAGAIN - a kernel resource was temporarily unavailable. | |
204 | */ | |
205 | asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior) | |
206 | { | |
05b74384 PM |
207 | unsigned long end, tmp; |
208 | struct vm_area_struct * vma, *prev; | |
1da177e4 LT |
209 | int unmapped_error = 0; |
210 | int error = -EINVAL; | |
211 | size_t len; | |
212 | ||
213 | down_write(¤t->mm->mmap_sem); | |
214 | ||
215 | if (start & ~PAGE_MASK) | |
216 | goto out; | |
217 | len = (len_in + ~PAGE_MASK) & PAGE_MASK; | |
218 | ||
219 | /* Check to see whether len was rounded up from small -ve to zero */ | |
220 | if (len_in && !len) | |
221 | goto out; | |
222 | ||
223 | end = start + len; | |
224 | if (end < start) | |
225 | goto out; | |
226 | ||
227 | error = 0; | |
228 | if (end == start) | |
229 | goto out; | |
230 | ||
231 | /* | |
232 | * If the interval [start,end) covers some unmapped address | |
233 | * ranges, just ignore them, but return -ENOMEM at the end. | |
05b74384 | 234 | * - different from the way of handling in mlock etc. |
1da177e4 | 235 | */ |
05b74384 PM |
236 | vma = find_vma_prev(current->mm, start, &prev); |
237 | if (!vma && prev) | |
238 | vma = prev->vm_next; | |
1da177e4 LT |
239 | for (;;) { |
240 | /* Still start < end. */ | |
241 | error = -ENOMEM; | |
242 | if (!vma) | |
243 | goto out; | |
244 | ||
05b74384 | 245 | /* Here start < (end|vma->vm_end). */ |
1da177e4 LT |
246 | if (start < vma->vm_start) { |
247 | unmapped_error = -ENOMEM; | |
248 | start = vma->vm_start; | |
05b74384 PM |
249 | if (start >= end) |
250 | goto out; | |
1da177e4 LT |
251 | } |
252 | ||
05b74384 PM |
253 | /* Here vma->vm_start <= start < (end|vma->vm_end) */ |
254 | tmp = vma->vm_end; | |
255 | if (end < tmp) | |
256 | tmp = end; | |
1da177e4 | 257 | |
05b74384 PM |
258 | /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ |
259 | error = madvise_vma(vma, &prev, start, tmp, behavior); | |
1da177e4 LT |
260 | if (error) |
261 | goto out; | |
05b74384 PM |
262 | start = tmp; |
263 | if (start < prev->vm_end) | |
264 | start = prev->vm_end; | |
265 | error = unmapped_error; | |
266 | if (start >= end) | |
267 | goto out; | |
268 | vma = prev->vm_next; | |
1da177e4 | 269 | } |
1da177e4 LT |
270 | out: |
271 | up_write(¤t->mm->mmap_sem); | |
272 | return error; | |
273 | } |