4 * Copyright (C) 1999 Linus Torvalds
5 * Copyright (C) 2002 Christoph Hellwig
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/sched.h>
15 #include <linux/ksm.h>
18 * Any behaviour which results in changes to the vma->vm_flags needs to
19 * take mmap_sem for writing. Others, which simply traverse vmas, need
20 * to only take it for reading.
22 static int madvise_need_mmap_write(int behavior)
30 /* be safe, default to 1. list exceptions explicitly */
36 * We can potentially split a vm area into separate
37 * areas, each area with its own behavior.
39 static long madvise_behavior(struct vm_area_struct * vma,
40 struct vm_area_struct **prev,
41 unsigned long start, unsigned long end, int behavior)
43 struct mm_struct * mm = vma->vm_mm;
46 unsigned long new_flags = vma->vm_flags;
50 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
53 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
56 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
59 new_flags |= VM_DONTCOPY;
62 if (vma->vm_flags & VM_IO) {
66 new_flags &= ~VM_DONTCOPY;
69 case MADV_UNMERGEABLE:
70 error = ksm_madvise(vma, start, end, behavior, &new_flags);
75 error = hugepage_madvise(&new_flags);
81 if (new_flags == vma->vm_flags) {
86 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
87 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
88 vma->vm_file, pgoff, vma_policy(vma));
96 if (start != vma->vm_start) {
97 error = split_vma(mm, vma, start, 1);
102 if (end != vma->vm_end) {
103 error = split_vma(mm, vma, end, 0);
110 * vm_flags is protected by the mmap_sem held in write mode.
112 vma->vm_flags = new_flags;
115 if (error == -ENOMEM)
121 * Schedule all required I/O operations. Do not wait for completion.
123 static long madvise_willneed(struct vm_area_struct * vma,
124 struct vm_area_struct ** prev,
125 unsigned long start, unsigned long end)
127 struct file *file = vma->vm_file;
132 if (file->f_mapping->a_ops->get_xip_mem) {
133 /* no bad return value, but ignore advice */
138 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
139 if (end > vma->vm_end)
141 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
143 force_page_cache_readahead(file->f_mapping, file, start, end - start);
148 * Application no longer needs these pages. If the pages are dirty,
149 * it's OK to just throw them away. The app will be more careful about
150 * data it wants to keep. Be sure to free swap resources too. The
151 * zap_page_range call sets things up for shrink_active_list to actually free
152 * these pages later if no one else has touched them in the meantime,
153 * although we could add these pages to a global reuse list for
154 * shrink_active_list to pick up before reclaiming other pages.
156 * NB: This interface discards data rather than pushes it out to swap,
157 * as some implementations do. This has performance implications for
158 * applications like large transactional databases which want to discard
159 * pages in anonymous maps after committing to backing store the data
160 * that was kept in them. There is no reason to write this data out to
161 * the swap area if the application is discarding it.
163 * An interface that causes the system to free clean pages and flush
164 * dirty pages is already available as msync(MS_INVALIDATE).
166 static long madvise_dontneed(struct vm_area_struct * vma,
167 struct vm_area_struct ** prev,
168 unsigned long start, unsigned long end)
171 if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP))
174 if (unlikely(vma->vm_flags & VM_NONLINEAR)) {
175 struct zap_details details = {
176 .nonlinear_vma = vma,
177 .last_index = ULONG_MAX,
179 zap_page_range(vma, start, end - start, &details);
181 zap_page_range(vma, start, end - start, NULL);
186 * Application wants to free up the pages and associated backing store.
187 * This is effectively punching a hole into the middle of a file.
189 * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
190 * Other filesystems return -ENOSYS.
192 static long madvise_remove(struct vm_area_struct *vma,
193 struct vm_area_struct **prev,
194 unsigned long start, unsigned long end)
196 struct address_space *mapping;
197 loff_t offset, endoff;
200 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
202 if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB))
205 if (!vma->vm_file || !vma->vm_file->f_mapping
206 || !vma->vm_file->f_mapping->host) {
210 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
213 mapping = vma->vm_file->f_mapping;
215 offset = (loff_t)(start - vma->vm_start)
216 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
217 endoff = (loff_t)(end - vma->vm_start - 1)
218 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
220 /* vmtruncate_range needs to take i_mutex and i_alloc_sem */
221 up_read(¤t->mm->mmap_sem);
222 error = vmtruncate_range(mapping->host, offset, endoff);
223 down_read(¤t->mm->mmap_sem);
227 #ifdef CONFIG_MEMORY_FAILURE
229 * Error injection support for memory error handling.
231 static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end)
235 if (!capable(CAP_SYS_ADMIN))
237 for (; start < end; start += PAGE_SIZE) {
239 int ret = get_user_pages_fast(start, 1, 0, &p);
242 if (bhv == MADV_SOFT_OFFLINE) {
243 printk(KERN_INFO "Soft offlining page %lx at %lx\n",
244 page_to_pfn(p), start);
245 ret = soft_offline_page(p, MF_COUNT_INCREASED);
250 printk(KERN_INFO "Injecting memory failure for page %lx at %lx\n",
251 page_to_pfn(p), start);
252 /* Ignore return value for now */
253 __memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED);
260 madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
261 unsigned long start, unsigned long end, int behavior)
265 return madvise_remove(vma, prev, start, end);
267 return madvise_willneed(vma, prev, start, end);
269 return madvise_dontneed(vma, prev, start, end);
271 return madvise_behavior(vma, prev, start, end, behavior);
276 madvise_behavior_valid(int behavior)
282 case MADV_SEQUENTIAL:
289 case MADV_UNMERGEABLE:
291 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
302 * The madvise(2) system call.
304 * Applications can use madvise() to advise the kernel how it should
305 * handle paging I/O in this VM area. The idea is to help the kernel
306 * use appropriate read-ahead and caching techniques. The information
307 * provided is advisory only, and can be safely disregarded by the
308 * kernel without affecting the correct operation of the application.
311 * MADV_NORMAL - the default behavior is to read clusters. This
312 * results in some read-ahead and read-behind.
313 * MADV_RANDOM - the system should read the minimum amount of data
314 * on any access, since it is unlikely that the appli-
315 * cation will need more than what it asks for.
316 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
317 * once, so they can be aggressively read ahead, and
318 * can be freed soon after they are accessed.
319 * MADV_WILLNEED - the application is notifying the system to read
321 * MADV_DONTNEED - the application is finished with the given range,
322 * so the kernel can free resources associated with it.
323 * MADV_REMOVE - the application wants to free up the given range of
324 * pages and associated backing store.
325 * MADV_DONTFORK - omit this area from child's address space when forking:
326 * typically, to avoid COWing pages pinned by get_user_pages().
327 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
328 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
329 * this area with pages of identical content from other such areas.
330 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
334 * -EINVAL - start + len < 0, start is not page-aligned,
335 * "behavior" is not a valid value, or application
336 * is attempting to release locked or shared pages.
337 * -ENOMEM - addresses in the specified range are not currently
338 * mapped, or are outside the AS of the process.
339 * -EIO - an I/O error occurred while paging in data.
340 * -EBADF - map exists, but area maps something that isn't a file.
341 * -EAGAIN - a kernel resource was temporarily unavailable.
343 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
345 unsigned long end, tmp;
346 struct vm_area_struct * vma, *prev;
347 int unmapped_error = 0;
352 #ifdef CONFIG_MEMORY_FAILURE
353 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
354 return madvise_hwpoison(behavior, start, start+len_in);
356 if (!madvise_behavior_valid(behavior))
359 write = madvise_need_mmap_write(behavior);
361 down_write(¤t->mm->mmap_sem);
363 down_read(¤t->mm->mmap_sem);
365 if (start & ~PAGE_MASK)
367 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
369 /* Check to see whether len was rounded up from small -ve to zero */
382 * If the interval [start,end) covers some unmapped address
383 * ranges, just ignore them, but return -ENOMEM at the end.
384 * - different from the way of handling in mlock etc.
386 vma = find_vma_prev(current->mm, start, &prev);
387 if (vma && start > vma->vm_start)
391 /* Still start < end. */
396 /* Here start < (end|vma->vm_end). */
397 if (start < vma->vm_start) {
398 unmapped_error = -ENOMEM;
399 start = vma->vm_start;
404 /* Here vma->vm_start <= start < (end|vma->vm_end) */
409 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
410 error = madvise_vma(vma, &prev, start, tmp, behavior);
414 if (prev && start < prev->vm_end)
415 start = prev->vm_end;
416 error = unmapped_error;
421 else /* madvise_remove dropped mmap_sem */
422 vma = find_vma(current->mm, start);
426 up_write(¤t->mm->mmap_sem);
428 up_read(¤t->mm->mmap_sem);