blob: 57ad276900c94903a2febd53e1c0d995958a38a9 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * mm/rmap.c - physical to virtual reverse mappings
3 *
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL).
6 *
7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible.
9 *
10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode.
13 *
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004
18 */
19
20/*
21 * Lock ordering in mm:
22 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080023 * inode->i_mutex (while writing or truncating, not reading or faulting)
Nick Piggin82591e62006-10-19 23:29:10 -070024 * inode->i_alloc_sem (vmtruncate_range)
25 * mm->mmap_sem
26 * page->flags PG_locked (lock_page)
27 * mapping->i_mmap_lock
28 * anon_vma->lock
29 * mm->page_table_lock or pte_lock
30 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
31 * swap_lock (in swap_duplicate, swap_info_get)
32 * mmlist_lock (in mmput, drain_mmlist and others)
33 * mapping->private_lock (in __set_page_dirty_buffers)
34 * inode_lock (in set_page_dirty's __mark_inode_dirty)
35 * sb_lock (within inode_lock in fs/fs-writeback.c)
36 * mapping->tree_lock (widely used, in set_page_dirty,
37 * in arch-dependent flush_dcache_mmap_lock,
38 * within inode_lock in __sync_single_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -070039 */
40
41#include <linux/mm.h>
42#include <linux/pagemap.h>
43#include <linux/swap.h>
44#include <linux/swapops.h>
45#include <linux/slab.h>
46#include <linux/init.h>
47#include <linux/rmap.h>
48#include <linux/rcupdate.h>
Christoph Lametera48d07a2006-02-01 03:05:38 -080049#include <linux/module.h>
Nick Piggin7de6b802006-12-22 01:09:33 -080050#include <linux/kallsyms.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
52#include <asm/tlbflush.h>
53
Pekka Enbergfcc234f2006-03-22 00:08:13 -080054struct kmem_cache *anon_vma_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070055
Linus Torvalds1da177e2005-04-16 15:20:36 -070056/* This must be called under the mmap_sem. */
57int anon_vma_prepare(struct vm_area_struct *vma)
58{
59 struct anon_vma *anon_vma = vma->anon_vma;
60
61 might_sleep();
62 if (unlikely(!anon_vma)) {
63 struct mm_struct *mm = vma->vm_mm;
64 struct anon_vma *allocated, *locked;
65
66 anon_vma = find_mergeable_anon_vma(vma);
67 if (anon_vma) {
68 allocated = NULL;
69 locked = anon_vma;
70 spin_lock(&locked->lock);
71 } else {
72 anon_vma = anon_vma_alloc();
73 if (unlikely(!anon_vma))
74 return -ENOMEM;
75 allocated = anon_vma;
76 locked = NULL;
77 }
78
79 /* page_table_lock to protect against threads */
80 spin_lock(&mm->page_table_lock);
81 if (likely(!vma->anon_vma)) {
82 vma->anon_vma = anon_vma;
Christoph Lameter06972122006-06-23 02:03:35 -070083 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -070084 allocated = NULL;
85 }
86 spin_unlock(&mm->page_table_lock);
87
88 if (locked)
89 spin_unlock(&locked->lock);
90 if (unlikely(allocated))
91 anon_vma_free(allocated);
92 }
93 return 0;
94}
95
96void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next)
97{
98 BUG_ON(vma->anon_vma != next->anon_vma);
99 list_del(&next->anon_vma_node);
100}
101
102void __anon_vma_link(struct vm_area_struct *vma)
103{
104 struct anon_vma *anon_vma = vma->anon_vma;
105
Hugh Dickins30acbab2007-06-27 14:09:53 -0700106 if (anon_vma)
Christoph Lameter06972122006-06-23 02:03:35 -0700107 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108}
109
110void anon_vma_link(struct vm_area_struct *vma)
111{
112 struct anon_vma *anon_vma = vma->anon_vma;
113
114 if (anon_vma) {
115 spin_lock(&anon_vma->lock);
Christoph Lameter06972122006-06-23 02:03:35 -0700116 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700117 spin_unlock(&anon_vma->lock);
118 }
119}
120
121void anon_vma_unlink(struct vm_area_struct *vma)
122{
123 struct anon_vma *anon_vma = vma->anon_vma;
124 int empty;
125
126 if (!anon_vma)
127 return;
128
129 spin_lock(&anon_vma->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 list_del(&vma->anon_vma_node);
131
132 /* We must garbage collect the anon_vma if it's empty */
133 empty = list_empty(&anon_vma->head);
134 spin_unlock(&anon_vma->lock);
135
136 if (empty)
137 anon_vma_free(anon_vma);
138}
139
Christoph Lameter4ba9b9d2007-10-16 23:25:51 -0700140static void anon_vma_ctor(struct kmem_cache *cachep, void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700141{
Christoph Lametera35afb82007-05-16 22:10:57 -0700142 struct anon_vma *anon_vma = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143
Christoph Lametera35afb82007-05-16 22:10:57 -0700144 spin_lock_init(&anon_vma->lock);
145 INIT_LIST_HEAD(&anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146}
147
148void __init anon_vma_init(void)
149{
150 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
Paul Mundt20c2df82007-07-20 10:11:58 +0900151 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152}
153
154/*
155 * Getting a lock on a stable anon_vma from a page off the LRU is
156 * tricky: page_lock_anon_vma rely on RCU to guard against the races.
157 */
158static struct anon_vma *page_lock_anon_vma(struct page *page)
159{
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800160 struct anon_vma *anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161 unsigned long anon_mapping;
162
163 rcu_read_lock();
164 anon_mapping = (unsigned long) page->mapping;
165 if (!(anon_mapping & PAGE_MAPPING_ANON))
166 goto out;
167 if (!page_mapped(page))
168 goto out;
169
170 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
171 spin_lock(&anon_vma->lock);
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800172 return anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173out:
174 rcu_read_unlock();
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800175 return NULL;
176}
177
178static void page_unlock_anon_vma(struct anon_vma *anon_vma)
179{
180 spin_unlock(&anon_vma->lock);
181 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182}
183
184/*
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800185 * At what user virtual address is page expected in @vma?
186 * Returns virtual address or -EFAULT if page's index/offset is not
187 * within the range mapped the @vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700188 */
189static inline unsigned long
190vma_address(struct page *page, struct vm_area_struct *vma)
191{
192 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
193 unsigned long address;
194
195 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
196 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800197 /* page should be within @vma mapping range */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700198 return -EFAULT;
199 }
200 return address;
201}
202
203/*
204 * At what user virtual address is page expected in vma? checking that the
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800205 * page matches the vma: currently only used on anon pages, by unuse_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206 */
207unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
208{
209 if (PageAnon(page)) {
210 if ((void *)vma->anon_vma !=
211 (void *)page->mapping - PAGE_MAPPING_ANON)
212 return -EFAULT;
213 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800214 if (!vma->vm_file ||
215 vma->vm_file->f_mapping != page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 return -EFAULT;
217 } else
218 return -EFAULT;
219 return vma_address(page, vma);
220}
221
222/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700223 * Check that @page is mapped at @address into @mm.
224 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700225 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700226 */
Carsten Otteceffc072005-06-23 22:05:25 -0700227pte_t *page_check_address(struct page *page, struct mm_struct *mm,
Hugh Dickinsc0718802005-10-29 18:16:31 -0700228 unsigned long address, spinlock_t **ptlp)
Nikita Danilov81b40822005-05-01 08:58:36 -0700229{
230 pgd_t *pgd;
231 pud_t *pud;
232 pmd_t *pmd;
233 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700234 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700235
Nikita Danilov81b40822005-05-01 08:58:36 -0700236 pgd = pgd_offset(mm, address);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700237 if (!pgd_present(*pgd))
238 return NULL;
239
240 pud = pud_offset(pgd, address);
241 if (!pud_present(*pud))
242 return NULL;
243
244 pmd = pmd_offset(pud, address);
245 if (!pmd_present(*pmd))
246 return NULL;
247
248 pte = pte_offset_map(pmd, address);
249 /* Make a quick check before getting the lock */
250 if (!pte_present(*pte)) {
251 pte_unmap(pte);
252 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700253 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700254
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700255 ptl = pte_lockptr(mm, pmd);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700256 spin_lock(ptl);
257 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
258 *ptlp = ptl;
259 return pte;
260 }
261 pte_unmap_unlock(pte, ptl);
262 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700263}
264
265/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700266 * Subfunctions of page_referenced: page_referenced_one called
267 * repeatedly from either page_referenced_anon or page_referenced_file.
268 */
269static int page_referenced_one(struct page *page,
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800270 struct vm_area_struct *vma, unsigned int *mapcount)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271{
272 struct mm_struct *mm = vma->vm_mm;
273 unsigned long address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700275 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 int referenced = 0;
277
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 address = vma_address(page, vma);
279 if (address == -EFAULT)
280 goto out;
281
Hugh Dickinsc0718802005-10-29 18:16:31 -0700282 pte = page_check_address(page, mm, address, &ptl);
283 if (!pte)
284 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285
Hugh Dickins5a9bbdc2008-02-04 22:29:23 -0800286 if (vma->vm_flags & VM_LOCKED) {
287 referenced++;
288 *mapcount = 1; /* break early from loop */
289 } else if (ptep_clear_flush_young(vma, address, pte))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700290 referenced++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
Hugh Dickinsc0718802005-10-29 18:16:31 -0700292 /* Pretend the page is referenced if the task has the
293 swap token and is in the middle of a page fault. */
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800294 if (mm != current->mm && has_swap_token(mm) &&
Hugh Dickinsc0718802005-10-29 18:16:31 -0700295 rwsem_is_locked(&mm->mmap_sem))
296 referenced++;
297
298 (*mapcount)--;
299 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300out:
301 return referenced;
302}
303
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800304static int page_referenced_anon(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305{
306 unsigned int mapcount;
307 struct anon_vma *anon_vma;
308 struct vm_area_struct *vma;
309 int referenced = 0;
310
311 anon_vma = page_lock_anon_vma(page);
312 if (!anon_vma)
313 return referenced;
314
315 mapcount = page_mapcount(page);
316 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800317 referenced += page_referenced_one(page, vma, &mapcount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318 if (!mapcount)
319 break;
320 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800321
322 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700323 return referenced;
324}
325
326/**
327 * page_referenced_file - referenced check for object-based rmap
328 * @page: the page we're checking references on.
329 *
330 * For an object-based mapped page, find all the places it is mapped and
331 * check/clear the referenced flag. This is done by following the page->mapping
332 * pointer, then walking the chain of vmas it holds. It returns the number
333 * of references it found.
334 *
335 * This function is only called from page_referenced for object-based pages.
336 */
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800337static int page_referenced_file(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700338{
339 unsigned int mapcount;
340 struct address_space *mapping = page->mapping;
341 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
342 struct vm_area_struct *vma;
343 struct prio_tree_iter iter;
344 int referenced = 0;
345
346 /*
347 * The caller's checks on page->mapping and !PageAnon have made
348 * sure that this is a file page: the check for page->mapping
349 * excludes the case just before it gets set on an anon page.
350 */
351 BUG_ON(PageAnon(page));
352
353 /*
354 * The page lock not only makes sure that page->mapping cannot
355 * suddenly be NULLified by truncation, it makes sure that the
356 * structure at mapping cannot be freed and reused yet,
357 * so we can safely take mapping->i_mmap_lock.
358 */
359 BUG_ON(!PageLocked(page));
360
361 spin_lock(&mapping->i_mmap_lock);
362
363 /*
364 * i_mmap_lock does not stabilize mapcount at all, but mapcount
365 * is more likely to be accurate if we note it after spinning.
366 */
367 mapcount = page_mapcount(page);
368
369 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
370 if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE))
371 == (VM_LOCKED|VM_MAYSHARE)) {
372 referenced++;
373 break;
374 }
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800375 referenced += page_referenced_one(page, vma, &mapcount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 if (!mapcount)
377 break;
378 }
379
380 spin_unlock(&mapping->i_mmap_lock);
381 return referenced;
382}
383
384/**
385 * page_referenced - test if the page was referenced
386 * @page: the page to test
387 * @is_locked: caller holds lock on the page
388 *
389 * Quick test_and_clear_referenced for all mappings to a page,
390 * returns the number of ptes which referenced the page.
391 */
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800392int page_referenced(struct page *page, int is_locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700393{
394 int referenced = 0;
395
Linus Torvalds1da177e2005-04-16 15:20:36 -0700396 if (page_test_and_clear_young(page))
397 referenced++;
398
399 if (TestClearPageReferenced(page))
400 referenced++;
401
402 if (page_mapped(page) && page->mapping) {
403 if (PageAnon(page))
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800404 referenced += page_referenced_anon(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700405 else if (is_locked)
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800406 referenced += page_referenced_file(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 else if (TestSetPageLocked(page))
408 referenced++;
409 else {
410 if (page->mapping)
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800411 referenced += page_referenced_file(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700412 unlock_page(page);
413 }
414 }
415 return referenced;
416}
417
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700418static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
419{
420 struct mm_struct *mm = vma->vm_mm;
421 unsigned long address;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100422 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700423 spinlock_t *ptl;
424 int ret = 0;
425
426 address = vma_address(page, vma);
427 if (address == -EFAULT)
428 goto out;
429
430 pte = page_check_address(page, mm, address, &ptl);
431 if (!pte)
432 goto out;
433
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100434 if (pte_dirty(*pte) || pte_write(*pte)) {
435 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700436
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100437 flush_cache_page(vma, address, pte_pfn(*pte));
438 entry = ptep_clear_flush(vma, address, pte);
439 entry = pte_wrprotect(entry);
440 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -0800441 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100442 ret = 1;
443 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700444
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700445 pte_unmap_unlock(pte, ptl);
446out:
447 return ret;
448}
449
450static int page_mkclean_file(struct address_space *mapping, struct page *page)
451{
452 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
453 struct vm_area_struct *vma;
454 struct prio_tree_iter iter;
455 int ret = 0;
456
457 BUG_ON(PageAnon(page));
458
459 spin_lock(&mapping->i_mmap_lock);
460 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
461 if (vma->vm_flags & VM_SHARED)
462 ret += page_mkclean_one(page, vma);
463 }
464 spin_unlock(&mapping->i_mmap_lock);
465 return ret;
466}
467
468int page_mkclean(struct page *page)
469{
470 int ret = 0;
471
472 BUG_ON(!PageLocked(page));
473
474 if (page_mapped(page)) {
475 struct address_space *mapping = page_mapping(page);
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100476 if (mapping) {
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700477 ret = page_mkclean_file(mapping, page);
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100478 if (page_test_dirty(page)) {
479 page_clear_dirty(page);
480 ret = 1;
481 }
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200482 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700483 }
484
485 return ret;
486}
Jaya Kumar60b59be2007-05-08 00:37:37 -0700487EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700488
Linus Torvalds1da177e2005-04-16 15:20:36 -0700489/**
Nick Piggin9617d952006-01-06 00:11:12 -0800490 * page_set_anon_rmap - setup new anonymous rmap
491 * @page: the page to add the mapping to
492 * @vma: the vm area in which the mapping is added
493 * @address: the user virtual address mapped
494 */
495static void __page_set_anon_rmap(struct page *page,
496 struct vm_area_struct *vma, unsigned long address)
497{
498 struct anon_vma *anon_vma = vma->anon_vma;
499
500 BUG_ON(!anon_vma);
501 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
502 page->mapping = (struct address_space *) anon_vma;
503
504 page->index = linear_page_index(vma, address);
505
Nick Piggina74609f2006-01-06 00:11:20 -0800506 /*
507 * nr_mapped state can be updated without turning off
508 * interrupts because it is not modified via interrupt.
509 */
Christoph Lameterf3dbd342006-06-30 01:55:36 -0700510 __inc_zone_page_state(page, NR_ANON_PAGES);
Nick Piggin9617d952006-01-06 00:11:12 -0800511}
512
513/**
Nick Pigginc97a9e12007-05-16 22:11:21 -0700514 * page_set_anon_rmap - sanity check anonymous rmap addition
515 * @page: the page to add the mapping to
516 * @vma: the vm area in which the mapping is added
517 * @address: the user virtual address mapped
518 */
519static void __page_check_anon_rmap(struct page *page,
520 struct vm_area_struct *vma, unsigned long address)
521{
522#ifdef CONFIG_DEBUG_VM
523 /*
524 * The page's anon-rmap details (mapping and index) are guaranteed to
525 * be set up correctly at this point.
526 *
527 * We have exclusion against page_add_anon_rmap because the caller
528 * always holds the page locked, except if called from page_dup_rmap,
529 * in which case the page is already known to be setup.
530 *
531 * We have exclusion against page_add_new_anon_rmap because those pages
532 * are initially only visible via the pagetables, and the pte is locked
533 * over the call to page_add_new_anon_rmap.
534 */
535 struct anon_vma *anon_vma = vma->anon_vma;
536 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
537 BUG_ON(page->mapping != (struct address_space *)anon_vma);
538 BUG_ON(page->index != linear_page_index(vma, address));
539#endif
540}
541
542/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700543 * page_add_anon_rmap - add pte mapping to an anonymous page
544 * @page: the page to add the mapping to
545 * @vma: the vm area in which the mapping is added
546 * @address: the user virtual address mapped
547 *
Nick Pigginc97a9e12007-05-16 22:11:21 -0700548 * The caller needs to hold the pte lock and the page must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700549 */
550void page_add_anon_rmap(struct page *page,
551 struct vm_area_struct *vma, unsigned long address)
552{
Nick Pigginc97a9e12007-05-16 22:11:21 -0700553 VM_BUG_ON(!PageLocked(page));
554 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Nick Piggin9617d952006-01-06 00:11:12 -0800555 if (atomic_inc_and_test(&page->_mapcount))
556 __page_set_anon_rmap(page, vma, address);
Nick Pigginc97a9e12007-05-16 22:11:21 -0700557 else
558 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559}
560
Nick Piggin9617d952006-01-06 00:11:12 -0800561/*
562 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
563 * @page: the page to add the mapping to
564 * @vma: the vm area in which the mapping is added
565 * @address: the user virtual address mapped
566 *
567 * Same as page_add_anon_rmap but must only be called on *new* pages.
568 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -0700569 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -0800570 */
571void page_add_new_anon_rmap(struct page *page,
572 struct vm_area_struct *vma, unsigned long address)
573{
Nick Pigginc97a9e12007-05-16 22:11:21 -0700574 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Nick Piggin9617d952006-01-06 00:11:12 -0800575 atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */
576 __page_set_anon_rmap(page, vma, address);
577}
578
Linus Torvalds1da177e2005-04-16 15:20:36 -0700579/**
580 * page_add_file_rmap - add pte mapping to a file page
581 * @page: the page to add the mapping to
582 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700583 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700584 */
585void page_add_file_rmap(struct page *page)
586{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700587 if (atomic_inc_and_test(&page->_mapcount))
Christoph Lameter65ba55f2006-06-30 01:55:34 -0700588 __inc_zone_page_state(page, NR_FILE_MAPPED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589}
590
Nick Pigginc97a9e12007-05-16 22:11:21 -0700591#ifdef CONFIG_DEBUG_VM
592/**
593 * page_dup_rmap - duplicate pte mapping to a page
594 * @page: the page to add the mapping to
595 *
596 * For copy_page_range only: minimal extract from page_add_file_rmap /
597 * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's
598 * quicker.
599 *
600 * The caller needs to hold the pte lock.
601 */
602void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
603{
604 BUG_ON(page_mapcount(page) == 0);
605 if (PageAnon(page))
606 __page_check_anon_rmap(page, vma, address);
607 atomic_inc(&page->_mapcount);
608}
609#endif
610
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611/**
612 * page_remove_rmap - take down pte mapping from a page
613 * @page: page to remove mapping from
614 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700615 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700616 */
Nick Piggin7de6b802006-12-22 01:09:33 -0800617void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700618{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700619 if (atomic_add_negative(-1, &page->_mapcount)) {
Nick Pigginb7ab7952006-03-22 00:08:42 -0800620 if (unlikely(page_mapcount(page) < 0)) {
Dave Jonesef2bf0d2006-01-08 01:01:00 -0800621 printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));
Nick Piggin7de6b802006-12-22 01:09:33 -0800622 printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(page));
Dave Jonesef2bf0d2006-01-08 01:01:00 -0800623 printk (KERN_EMERG " page->flags = %lx\n", page->flags);
624 printk (KERN_EMERG " page->count = %x\n", page_count(page));
625 printk (KERN_EMERG " page->mapping = %p\n", page->mapping);
Nick Piggin7de6b802006-12-22 01:09:33 -0800626 print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops);
Nick Piggin54cb8822007-07-19 01:46:59 -0700627 if (vma->vm_ops) {
Nick Piggin7de6b802006-12-22 01:09:33 -0800628 print_symbol (KERN_EMERG " vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage);
Nick Piggin54cb8822007-07-19 01:46:59 -0700629 print_symbol (KERN_EMERG " vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault);
630 }
Nick Piggin7de6b802006-12-22 01:09:33 -0800631 if (vma->vm_file && vma->vm_file->f_op)
632 print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap);
Dave Jonesb16bc642006-10-11 01:21:27 -0700633 BUG();
Dave Jonesef2bf0d2006-01-08 01:01:00 -0800634 }
Dave Jonesb16bc642006-10-11 01:21:27 -0700635
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636 /*
637 * It would be tidy to reset the PageAnon mapping here,
638 * but that might overwrite a racing page_add_anon_rmap
639 * which increments mapcount after us but sets mapping
640 * before us: so leave the reset to free_hot_cold_page,
641 * and remember that it's only reliable while mapped.
642 * Leaving it set also helps swapoff to reinstate ptes
643 * faster for those pages still in swapcache.
644 */
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200645 if (page_test_dirty(page)) {
646 page_clear_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700647 set_page_dirty(page);
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200648 }
Christoph Lameterf3dbd342006-06-30 01:55:36 -0700649 __dec_zone_page_state(page,
650 PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651 }
652}
653
654/*
655 * Subfunctions of try_to_unmap: try_to_unmap_one called
656 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
657 */
Christoph Lametera48d07a2006-02-01 03:05:38 -0800658static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
Christoph Lameter73523492006-06-23 02:03:27 -0700659 int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660{
661 struct mm_struct *mm = vma->vm_mm;
662 unsigned long address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700663 pte_t *pte;
664 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700665 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666 int ret = SWAP_AGAIN;
667
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 address = vma_address(page, vma);
669 if (address == -EFAULT)
670 goto out;
671
Hugh Dickinsc0718802005-10-29 18:16:31 -0700672 pte = page_check_address(page, mm, address, &ptl);
673 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -0700674 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675
676 /*
677 * If the page is mlock()d, we cannot swap it out.
678 * If it's recently referenced (perhaps page_referenced
679 * skipped over this mm) then we should reactivate it.
680 */
Christoph Lametere6a15302006-06-25 05:46:49 -0700681 if (!migration && ((vma->vm_flags & VM_LOCKED) ||
682 (ptep_clear_flush_young(vma, address, pte)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700683 ret = SWAP_FAIL;
684 goto out_unmap;
685 }
686
Linus Torvalds1da177e2005-04-16 15:20:36 -0700687 /* Nuke the page table entry. */
688 flush_cache_page(vma, address, page_to_pfn(page));
689 pteval = ptep_clear_flush(vma, address, pte);
690
691 /* Move the dirty bit to the physical page now the pte is gone. */
692 if (pte_dirty(pteval))
693 set_page_dirty(page);
694
Hugh Dickins365e9c872005-10-29 18:16:18 -0700695 /* Update high watermark before we lower rss */
696 update_hiwater_rss(mm);
697
Linus Torvalds1da177e2005-04-16 15:20:36 -0700698 if (PageAnon(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700699 swp_entry_t entry = { .val = page_private(page) };
Christoph Lameter06972122006-06-23 02:03:35 -0700700
701 if (PageSwapCache(page)) {
702 /*
703 * Store the swap location in the pte.
704 * See handle_pte_fault() ...
705 */
706 swap_duplicate(entry);
707 if (list_empty(&mm->mmlist)) {
708 spin_lock(&mmlist_lock);
709 if (list_empty(&mm->mmlist))
710 list_add(&mm->mmlist, &init_mm.mmlist);
711 spin_unlock(&mmlist_lock);
712 }
Christoph Lameter442c9132006-06-23 02:03:38 -0700713 dec_mm_counter(mm, anon_rss);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700714#ifdef CONFIG_MIGRATION
Christoph Lameter06972122006-06-23 02:03:35 -0700715 } else {
716 /*
717 * Store the pfn of the page in a special migration
718 * pte. do_swap_page() will wait until the migration
719 * pte is removed and then restart fault handling.
720 */
721 BUG_ON(!migration);
722 entry = make_migration_entry(page, pte_write(pteval));
Christoph Lameter04e62a22006-06-23 02:03:38 -0700723#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700724 }
725 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
726 BUG_ON(pte_file(*pte));
Hugh Dickins42946212005-10-29 18:16:05 -0700727 } else
Christoph Lameter04e62a22006-06-23 02:03:38 -0700728#ifdef CONFIG_MIGRATION
729 if (migration) {
730 /* Establish migration entry for a file page */
731 swp_entry_t entry;
732 entry = make_migration_entry(page, pte_write(pteval));
733 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
734 } else
735#endif
Hugh Dickins42946212005-10-29 18:16:05 -0700736 dec_mm_counter(mm, file_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700737
Christoph Lameter04e62a22006-06-23 02:03:38 -0700738
Nick Piggin7de6b802006-12-22 01:09:33 -0800739 page_remove_rmap(page, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740 page_cache_release(page);
741
742out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700743 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700744out:
745 return ret;
746}
747
748/*
749 * objrmap doesn't work for nonlinear VMAs because the assumption that
750 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
751 * Consequently, given a particular page and its ->index, we cannot locate the
752 * ptes which are mapping that page without an exhaustive linear search.
753 *
754 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
755 * maps the file to which the target page belongs. The ->vm_private_data field
756 * holds the current cursor into that scan. Successive searches will circulate
757 * around the vma's virtual address space.
758 *
759 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
760 * more scanning pressure is placed against them as well. Eventually pages
761 * will become fully unmapped and are eligible for eviction.
762 *
763 * For very sparsely populated VMAs this is a little inefficient - chances are
764 * there there won't be many ptes located within the scan cluster. In this case
765 * maybe we could scan further - to the end of the pte page, perhaps.
766 */
767#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
768#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
769
770static void try_to_unmap_cluster(unsigned long cursor,
771 unsigned int *mapcount, struct vm_area_struct *vma)
772{
773 struct mm_struct *mm = vma->vm_mm;
774 pgd_t *pgd;
775 pud_t *pud;
776 pmd_t *pmd;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700777 pte_t *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700779 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700780 struct page *page;
781 unsigned long address;
782 unsigned long end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700783
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 address = (vma->vm_start + cursor) & CLUSTER_MASK;
785 end = address + CLUSTER_SIZE;
786 if (address < vma->vm_start)
787 address = vma->vm_start;
788 if (end > vma->vm_end)
789 end = vma->vm_end;
790
791 pgd = pgd_offset(mm, address);
792 if (!pgd_present(*pgd))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700793 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794
795 pud = pud_offset(pgd, address);
796 if (!pud_present(*pud))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700797 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798
799 pmd = pmd_offset(pud, address);
800 if (!pmd_present(*pmd))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700801 return;
802
803 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700804
Hugh Dickins365e9c872005-10-29 18:16:18 -0700805 /* Update high watermark before we lower rss */
806 update_hiwater_rss(mm);
807
Hugh Dickinsc0718802005-10-29 18:16:31 -0700808 for (; address < end; pte++, address += PAGE_SIZE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809 if (!pte_present(*pte))
810 continue;
Linus Torvalds6aab3412005-11-28 14:34:23 -0800811 page = vm_normal_page(vma, address, *pte);
812 BUG_ON(!page || PageAnon(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813
814 if (ptep_clear_flush_young(vma, address, pte))
815 continue;
816
817 /* Nuke the page table entry. */
Ben Collinseca35132005-11-29 11:45:26 -0800818 flush_cache_page(vma, address, pte_pfn(*pte));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700819 pteval = ptep_clear_flush(vma, address, pte);
820
821 /* If nonlinear, store the file page offset in the pte. */
822 if (page->index != linear_page_index(vma, address))
823 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
824
825 /* Move the dirty bit to the physical page now the pte is gone. */
826 if (pte_dirty(pteval))
827 set_page_dirty(page);
828
Nick Piggin7de6b802006-12-22 01:09:33 -0800829 page_remove_rmap(page, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 page_cache_release(page);
Hugh Dickins42946212005-10-29 18:16:05 -0700831 dec_mm_counter(mm, file_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 (*mapcount)--;
833 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700834 pte_unmap_unlock(pte - 1, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835}
836
Christoph Lameter73523492006-06-23 02:03:27 -0700837static int try_to_unmap_anon(struct page *page, int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838{
839 struct anon_vma *anon_vma;
840 struct vm_area_struct *vma;
841 int ret = SWAP_AGAIN;
842
843 anon_vma = page_lock_anon_vma(page);
844 if (!anon_vma)
845 return ret;
846
847 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
Christoph Lameter73523492006-06-23 02:03:27 -0700848 ret = try_to_unmap_one(page, vma, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849 if (ret == SWAP_FAIL || !page_mapped(page))
850 break;
851 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800852
853 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700854 return ret;
855}
856
857/**
858 * try_to_unmap_file - unmap file page using the object-based rmap method
859 * @page: the page to unmap
860 *
861 * Find all the mappings of a page using the mapping pointer and the vma chains
862 * contained in the address_space struct it points to.
863 *
864 * This function is only called from try_to_unmap for object-based pages.
865 */
Christoph Lameter73523492006-06-23 02:03:27 -0700866static int try_to_unmap_file(struct page *page, int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867{
868 struct address_space *mapping = page->mapping;
869 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
870 struct vm_area_struct *vma;
871 struct prio_tree_iter iter;
872 int ret = SWAP_AGAIN;
873 unsigned long cursor;
874 unsigned long max_nl_cursor = 0;
875 unsigned long max_nl_size = 0;
876 unsigned int mapcount;
877
878 spin_lock(&mapping->i_mmap_lock);
879 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Christoph Lameter73523492006-06-23 02:03:27 -0700880 ret = try_to_unmap_one(page, vma, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881 if (ret == SWAP_FAIL || !page_mapped(page))
882 goto out;
883 }
884
885 if (list_empty(&mapping->i_mmap_nonlinear))
886 goto out;
887
888 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
889 shared.vm_set.list) {
Christoph Lametere6a15302006-06-25 05:46:49 -0700890 if ((vma->vm_flags & VM_LOCKED) && !migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700891 continue;
892 cursor = (unsigned long) vma->vm_private_data;
893 if (cursor > max_nl_cursor)
894 max_nl_cursor = cursor;
895 cursor = vma->vm_end - vma->vm_start;
896 if (cursor > max_nl_size)
897 max_nl_size = cursor;
898 }
899
900 if (max_nl_size == 0) { /* any nonlinears locked or reserved */
901 ret = SWAP_FAIL;
902 goto out;
903 }
904
905 /*
906 * We don't try to search for this page in the nonlinear vmas,
907 * and page_referenced wouldn't have found it anyway. Instead
908 * just walk the nonlinear vmas trying to age and unmap some.
909 * The mapcount of the page we came in with is irrelevant,
910 * but even so use it as a guide to how hard we should try?
911 */
912 mapcount = page_mapcount(page);
913 if (!mapcount)
914 goto out;
915 cond_resched_lock(&mapping->i_mmap_lock);
916
917 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
918 if (max_nl_cursor == 0)
919 max_nl_cursor = CLUSTER_SIZE;
920
921 do {
922 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
923 shared.vm_set.list) {
Christoph Lametere6a15302006-06-25 05:46:49 -0700924 if ((vma->vm_flags & VM_LOCKED) && !migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700925 continue;
926 cursor = (unsigned long) vma->vm_private_data;
Hugh Dickins839b9682005-09-03 15:54:43 -0700927 while ( cursor < max_nl_cursor &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700928 cursor < vma->vm_end - vma->vm_start) {
929 try_to_unmap_cluster(cursor, &mapcount, vma);
930 cursor += CLUSTER_SIZE;
931 vma->vm_private_data = (void *) cursor;
932 if ((int)mapcount <= 0)
933 goto out;
934 }
935 vma->vm_private_data = (void *) max_nl_cursor;
936 }
937 cond_resched_lock(&mapping->i_mmap_lock);
938 max_nl_cursor += CLUSTER_SIZE;
939 } while (max_nl_cursor <= max_nl_size);
940
941 /*
942 * Don't loop forever (perhaps all the remaining pages are
943 * in locked vmas). Reset cursor on all unreserved nonlinear
944 * vmas, now forgetting on which ones it had fallen behind.
945 */
Hugh Dickins101d2be2005-11-21 21:32:16 -0800946 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
947 vma->vm_private_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700948out:
949 spin_unlock(&mapping->i_mmap_lock);
950 return ret;
951}
952
953/**
954 * try_to_unmap - try to remove all page table mappings to a page
955 * @page: the page to get unmapped
956 *
957 * Tries to remove all the page table entries which are mapping this
958 * page, used in the pageout path. Caller must hold the page lock.
959 * Return values are:
960 *
961 * SWAP_SUCCESS - we succeeded in removing all mappings
962 * SWAP_AGAIN - we missed a mapping, try again later
963 * SWAP_FAIL - the page is unswappable
964 */
Christoph Lameter73523492006-06-23 02:03:27 -0700965int try_to_unmap(struct page *page, int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700966{
967 int ret;
968
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 BUG_ON(!PageLocked(page));
970
971 if (PageAnon(page))
Christoph Lameter73523492006-06-23 02:03:27 -0700972 ret = try_to_unmap_anon(page, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700973 else
Christoph Lameter73523492006-06-23 02:03:27 -0700974 ret = try_to_unmap_file(page, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700975
976 if (!page_mapped(page))
977 ret = SWAP_SUCCESS;
978 return ret;
979}
Nikita Danilov81b40822005-05-01 08:58:36 -0700980