blob: 60542d006ec16b0f0b48404493ff7f96c579862c [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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>
Prasanna Meda05b74382005-06-21 17:14:37 -070011#include <linux/mempolicy.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070012#include <linux/hugetlb.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040013#include <linux/sched.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014
15/*
Nick Piggin0a27a142007-05-06 14:49:53 -070016 * Any behaviour which results in changes to the vma->vm_flags needs to
17 * take mmap_sem for writing. Others, which simply traverse vmas, need
18 * to only take it for reading.
19 */
20static int madvise_need_mmap_write(int behavior)
21{
22 switch (behavior) {
23 case MADV_REMOVE:
24 case MADV_WILLNEED:
25 case MADV_DONTNEED:
26 return 0;
27 default:
28 /* be safe, default to 1. list exceptions explicitly */
29 return 1;
30 }
31}
32
33/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070034 * We can potentially split a vm area into separate
35 * areas, each area with its own behavior.
36 */
Prasanna Meda05b74382005-06-21 17:14:37 -070037static long madvise_behavior(struct vm_area_struct * vma,
38 struct vm_area_struct **prev,
39 unsigned long start, unsigned long end, int behavior)
Linus Torvalds1da177e2005-04-16 15:20:36 -070040{
41 struct mm_struct * mm = vma->vm_mm;
42 int error = 0;
Prasanna Meda05b74382005-06-21 17:14:37 -070043 pgoff_t pgoff;
Michael S. Tsirkinf8225662006-02-14 13:53:08 -080044 int new_flags = vma->vm_flags;
Prasanna Medae798c6e2005-06-21 17:14:36 -070045
46 switch (behavior) {
Michael S. Tsirkinf8225662006-02-14 13:53:08 -080047 case MADV_NORMAL:
48 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
49 break;
Prasanna Medae798c6e2005-06-21 17:14:36 -070050 case MADV_SEQUENTIAL:
Michael S. Tsirkinf8225662006-02-14 13:53:08 -080051 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
Prasanna Medae798c6e2005-06-21 17:14:36 -070052 break;
53 case MADV_RANDOM:
Michael S. Tsirkinf8225662006-02-14 13:53:08 -080054 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
Prasanna Medae798c6e2005-06-21 17:14:36 -070055 break;
Michael S. Tsirkinf8225662006-02-14 13:53:08 -080056 case MADV_DONTFORK:
57 new_flags |= VM_DONTCOPY;
58 break;
59 case MADV_DOFORK:
60 new_flags &= ~VM_DONTCOPY;
Prasanna Medae798c6e2005-06-21 17:14:36 -070061 break;
62 }
63
Prasanna Meda05b74382005-06-21 17:14:37 -070064 if (new_flags == vma->vm_flags) {
65 *prev = vma;
Hugh Dickins836d5ff2005-09-03 15:54:53 -070066 goto out;
Prasanna Meda05b74382005-06-21 17:14:37 -070067 }
68
69 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
70 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
71 vma->vm_file, pgoff, vma_policy(vma));
72 if (*prev) {
73 vma = *prev;
74 goto success;
75 }
76
77 *prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -070078
79 if (start != vma->vm_start) {
80 error = split_vma(mm, vma, start, 1);
81 if (error)
82 goto out;
83 }
84
85 if (end != vma->vm_end) {
86 error = split_vma(mm, vma, end, 0);
87 if (error)
88 goto out;
89 }
90
Hugh Dickins836d5ff2005-09-03 15:54:53 -070091success:
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 /*
93 * vm_flags is protected by the mmap_sem held in write mode.
94 */
Prasanna Medae798c6e2005-06-21 17:14:36 -070095 vma->vm_flags = new_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -070096
97out:
98 if (error == -ENOMEM)
99 error = -EAGAIN;
100 return error;
101}
102
103/*
104 * Schedule all required I/O operations. Do not wait for completion.
105 */
106static long madvise_willneed(struct vm_area_struct * vma,
Prasanna Meda05b74382005-06-21 17:14:37 -0700107 struct vm_area_struct ** prev,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108 unsigned long start, unsigned long end)
109{
110 struct file *file = vma->vm_file;
111
Suzuki1bef4002005-10-11 08:29:06 -0700112 if (!file)
113 return -EBADF;
114
Carsten Ottefe77ba62005-06-23 22:05:29 -0700115 if (file->f_mapping->a_ops->get_xip_page) {
116 /* no bad return value, but ignore advice */
117 return 0;
118 }
119
Prasanna Meda05b74382005-06-21 17:14:37 -0700120 *prev = vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700121 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
122 if (end > vma->vm_end)
123 end = vma->vm_end;
124 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
125
126 force_page_cache_readahead(file->f_mapping,
127 file, start, max_sane_readahead(end - start));
128 return 0;
129}
130
131/*
132 * Application no longer needs these pages. If the pages are dirty,
133 * it's OK to just throw them away. The app will be more careful about
134 * data it wants to keep. Be sure to free swap resources too. The
135 * zap_page_range call sets things up for refill_inactive to actually free
136 * these pages later if no one else has touched them in the meantime,
137 * although we could add these pages to a global reuse list for
138 * refill_inactive to pick up before reclaiming other pages.
139 *
140 * NB: This interface discards data rather than pushes it out to swap,
141 * as some implementations do. This has performance implications for
142 * applications like large transactional databases which want to discard
143 * pages in anonymous maps after committing to backing store the data
144 * that was kept in them. There is no reason to write this data out to
145 * the swap area if the application is discarding it.
146 *
147 * An interface that causes the system to free clean pages and flush
148 * dirty pages is already available as msync(MS_INVALIDATE).
149 */
150static long madvise_dontneed(struct vm_area_struct * vma,
Prasanna Meda05b74382005-06-21 17:14:37 -0700151 struct vm_area_struct ** prev,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152 unsigned long start, unsigned long end)
153{
Prasanna Meda05b74382005-06-21 17:14:37 -0700154 *prev = vma;
Linus Torvalds6aab3412005-11-28 14:34:23 -0800155 if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156 return -EINVAL;
157
158 if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
159 struct zap_details details = {
160 .nonlinear_vma = vma,
161 .last_index = ULONG_MAX,
162 };
163 zap_page_range(vma, start, end - start, &details);
164 } else
165 zap_page_range(vma, start, end - start, NULL);
166 return 0;
167}
168
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800169/*
170 * Application wants to free up the pages and associated backing store.
171 * This is effectively punching a hole into the middle of a file.
172 *
173 * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
174 * Other filesystems return -ENOSYS.
175 */
176static long madvise_remove(struct vm_area_struct *vma,
Nick Piggin00e9fa22007-03-16 13:38:10 -0800177 struct vm_area_struct **prev,
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800178 unsigned long start, unsigned long end)
179{
180 struct address_space *mapping;
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700181 loff_t offset, endoff;
182 int error;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800183
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700184 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
Nick Piggin00e9fa22007-03-16 13:38:10 -0800185
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800186 if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB))
187 return -EINVAL;
188
189 if (!vma->vm_file || !vma->vm_file->f_mapping
190 || !vma->vm_file->f_mapping->host) {
191 return -EINVAL;
192 }
193
Hugh Dickins69cf0fa2006-04-17 22:46:32 +0100194 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
195 return -EACCES;
196
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800197 mapping = vma->vm_file->f_mapping;
198
199 offset = (loff_t)(start - vma->vm_start)
200 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
201 endoff = (loff_t)(end - vma->vm_start - 1)
202 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700203
204 /* vmtruncate_range needs to take i_mutex and i_alloc_sem */
Nick Piggin0a27a142007-05-06 14:49:53 -0700205 up_read(&current->mm->mmap_sem);
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700206 error = vmtruncate_range(mapping->host, offset, endoff);
Nick Piggin0a27a142007-05-06 14:49:53 -0700207 down_read(&current->mm->mmap_sem);
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700208 return error;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800209}
210
suzuki165cd402005-07-27 11:43:59 -0700211static long
212madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
213 unsigned long start, unsigned long end, int behavior)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214{
Suzuki1bef4002005-10-11 08:29:06 -0700215 long error;
suzuki165cd402005-07-27 11:43:59 -0700216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 switch (behavior) {
Michael S. Tsirkinf8225662006-02-14 13:53:08 -0800218 case MADV_DOFORK:
219 if (vma->vm_flags & VM_IO) {
220 error = -EINVAL;
221 break;
222 }
223 case MADV_DONTFORK:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 case MADV_NORMAL:
225 case MADV_SEQUENTIAL:
226 case MADV_RANDOM:
Prasanna Meda05b74382005-06-21 17:14:37 -0700227 error = madvise_behavior(vma, prev, start, end, behavior);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700228 break;
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800229 case MADV_REMOVE:
Nick Piggin00e9fa22007-03-16 13:38:10 -0800230 error = madvise_remove(vma, prev, start, end);
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800231 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700232
233 case MADV_WILLNEED:
Prasanna Meda05b74382005-06-21 17:14:37 -0700234 error = madvise_willneed(vma, prev, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700235 break;
236
237 case MADV_DONTNEED:
Prasanna Meda05b74382005-06-21 17:14:37 -0700238 error = madvise_dontneed(vma, prev, start, end);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 break;
240
241 default:
242 error = -EINVAL;
243 break;
244 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 return error;
246}
247
248/*
249 * The madvise(2) system call.
250 *
251 * Applications can use madvise() to advise the kernel how it should
252 * handle paging I/O in this VM area. The idea is to help the kernel
253 * use appropriate read-ahead and caching techniques. The information
254 * provided is advisory only, and can be safely disregarded by the
255 * kernel without affecting the correct operation of the application.
256 *
257 * behavior values:
258 * MADV_NORMAL - the default behavior is to read clusters. This
259 * results in some read-ahead and read-behind.
260 * MADV_RANDOM - the system should read the minimum amount of data
261 * on any access, since it is unlikely that the appli-
262 * cation will need more than what it asks for.
263 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
264 * once, so they can be aggressively read ahead, and
265 * can be freed soon after they are accessed.
266 * MADV_WILLNEED - the application is notifying the system to read
267 * some pages ahead.
268 * MADV_DONTNEED - the application is finished with the given range,
269 * so the kernel can free resources associated with it.
Badari Pulavartyf6b3ec22006-01-06 00:10:38 -0800270 * MADV_REMOVE - the application wants to free up the given range of
271 * pages and associated backing store.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 *
273 * return values:
274 * zero - success
275 * -EINVAL - start + len < 0, start is not page-aligned,
276 * "behavior" is not a valid value, or application
277 * is attempting to release locked or shared pages.
278 * -ENOMEM - addresses in the specified range are not currently
279 * mapped, or are outside the AS of the process.
280 * -EIO - an I/O error occurred while paging in data.
281 * -EBADF - map exists, but area maps something that isn't a file.
282 * -EAGAIN - a kernel resource was temporarily unavailable.
283 */
284asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior)
285{
Prasanna Meda05b74382005-06-21 17:14:37 -0700286 unsigned long end, tmp;
287 struct vm_area_struct * vma, *prev;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700288 int unmapped_error = 0;
289 int error = -EINVAL;
290 size_t len;
291
Nick Piggin0a27a142007-05-06 14:49:53 -0700292 if (madvise_need_mmap_write(behavior))
293 down_write(&current->mm->mmap_sem);
294 else
295 down_read(&current->mm->mmap_sem);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700296
297 if (start & ~PAGE_MASK)
298 goto out;
299 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
300
301 /* Check to see whether len was rounded up from small -ve to zero */
302 if (len_in && !len)
303 goto out;
304
305 end = start + len;
306 if (end < start)
307 goto out;
308
309 error = 0;
310 if (end == start)
311 goto out;
312
313 /*
314 * If the interval [start,end) covers some unmapped address
315 * ranges, just ignore them, but return -ENOMEM at the end.
Prasanna Meda05b74382005-06-21 17:14:37 -0700316 * - different from the way of handling in mlock etc.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700317 */
Prasanna Meda05b74382005-06-21 17:14:37 -0700318 vma = find_vma_prev(current->mm, start, &prev);
Hugh Dickins836d5ff2005-09-03 15:54:53 -0700319 if (vma && start > vma->vm_start)
320 prev = vma;
321
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322 for (;;) {
323 /* Still start < end. */
324 error = -ENOMEM;
325 if (!vma)
326 goto out;
327
Prasanna Meda05b74382005-06-21 17:14:37 -0700328 /* Here start < (end|vma->vm_end). */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700329 if (start < vma->vm_start) {
330 unmapped_error = -ENOMEM;
331 start = vma->vm_start;
Prasanna Meda05b74382005-06-21 17:14:37 -0700332 if (start >= end)
333 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 }
335
Prasanna Meda05b74382005-06-21 17:14:37 -0700336 /* Here vma->vm_start <= start < (end|vma->vm_end) */
337 tmp = vma->vm_end;
338 if (end < tmp)
339 tmp = end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340
Prasanna Meda05b74382005-06-21 17:14:37 -0700341 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
342 error = madvise_vma(vma, &prev, start, tmp, behavior);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343 if (error)
344 goto out;
Prasanna Meda05b74382005-06-21 17:14:37 -0700345 start = tmp;
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700346 if (prev && start < prev->vm_end)
Prasanna Meda05b74382005-06-21 17:14:37 -0700347 start = prev->vm_end;
348 error = unmapped_error;
349 if (start >= end)
350 goto out;
Hugh Dickins90ed52e2007-03-29 01:20:38 -0700351 if (prev)
352 vma = prev->vm_next;
353 else /* madvise_remove dropped mmap_sem */
354 vma = find_vma(current->mm, start);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700355 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356out:
Nick Piggin0a27a142007-05-06 14:49:53 -0700357 if (madvise_need_mmap_write(behavior))
358 up_write(&current->mm->mmap_sem);
359 else
360 up_read(&current->mm->mmap_sem);
361
Linus Torvalds1da177e2005-04-16 15:20:36 -0700362 return error;
363}