blob: 1ea4e6fcee77986f673d578a42bece82a92fb81e [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>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080051#include <linux/memcontrol.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070052#include <linux/mmu_notifier.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070053
54#include <asm/tlbflush.h>
55
Pekka Enbergfcc234f2006-03-22 00:08:13 -080056struct kmem_cache *anon_vma_cachep;
Linus Torvalds1da177e2005-04-16 15:20:36 -070057
Linus Torvalds1da177e2005-04-16 15:20:36 -070058/* This must be called under the mmap_sem. */
59int anon_vma_prepare(struct vm_area_struct *vma)
60{
61 struct anon_vma *anon_vma = vma->anon_vma;
62
63 might_sleep();
64 if (unlikely(!anon_vma)) {
65 struct mm_struct *mm = vma->vm_mm;
66 struct anon_vma *allocated, *locked;
67
68 anon_vma = find_mergeable_anon_vma(vma);
69 if (anon_vma) {
70 allocated = NULL;
71 locked = anon_vma;
72 spin_lock(&locked->lock);
73 } else {
74 anon_vma = anon_vma_alloc();
75 if (unlikely(!anon_vma))
76 return -ENOMEM;
77 allocated = anon_vma;
78 locked = NULL;
79 }
80
81 /* page_table_lock to protect against threads */
82 spin_lock(&mm->page_table_lock);
83 if (likely(!vma->anon_vma)) {
84 vma->anon_vma = anon_vma;
Christoph Lameter06972122006-06-23 02:03:35 -070085 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 allocated = NULL;
87 }
88 spin_unlock(&mm->page_table_lock);
89
90 if (locked)
91 spin_unlock(&locked->lock);
92 if (unlikely(allocated))
93 anon_vma_free(allocated);
94 }
95 return 0;
96}
97
98void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next)
99{
100 BUG_ON(vma->anon_vma != next->anon_vma);
101 list_del(&next->anon_vma_node);
102}
103
104void __anon_vma_link(struct vm_area_struct *vma)
105{
106 struct anon_vma *anon_vma = vma->anon_vma;
107
Hugh Dickins30acbab2007-06-27 14:09:53 -0700108 if (anon_vma)
Christoph Lameter06972122006-06-23 02:03:35 -0700109 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700110}
111
112void anon_vma_link(struct vm_area_struct *vma)
113{
114 struct anon_vma *anon_vma = vma->anon_vma;
115
116 if (anon_vma) {
117 spin_lock(&anon_vma->lock);
Christoph Lameter06972122006-06-23 02:03:35 -0700118 list_add_tail(&vma->anon_vma_node, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700119 spin_unlock(&anon_vma->lock);
120 }
121}
122
123void anon_vma_unlink(struct vm_area_struct *vma)
124{
125 struct anon_vma *anon_vma = vma->anon_vma;
126 int empty;
127
128 if (!anon_vma)
129 return;
130
131 spin_lock(&anon_vma->lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132 list_del(&vma->anon_vma_node);
133
134 /* We must garbage collect the anon_vma if it's empty */
135 empty = list_empty(&anon_vma->head);
136 spin_unlock(&anon_vma->lock);
137
138 if (empty)
139 anon_vma_free(anon_vma);
140}
141
Alexey Dobriyan51cc5062008-07-25 19:45:34 -0700142static void anon_vma_ctor(void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700143{
Christoph Lametera35afb82007-05-16 22:10:57 -0700144 struct anon_vma *anon_vma = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700145
Christoph Lametera35afb82007-05-16 22:10:57 -0700146 spin_lock_init(&anon_vma->lock);
147 INIT_LIST_HEAD(&anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700148}
149
150void __init anon_vma_init(void)
151{
152 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
Paul Mundt20c2df82007-07-20 10:11:58 +0900153 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700154}
155
156/*
157 * Getting a lock on a stable anon_vma from a page off the LRU is
158 * tricky: page_lock_anon_vma rely on RCU to guard against the races.
159 */
160static struct anon_vma *page_lock_anon_vma(struct page *page)
161{
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800162 struct anon_vma *anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163 unsigned long anon_mapping;
164
165 rcu_read_lock();
166 anon_mapping = (unsigned long) page->mapping;
167 if (!(anon_mapping & PAGE_MAPPING_ANON))
168 goto out;
169 if (!page_mapped(page))
170 goto out;
171
172 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
173 spin_lock(&anon_vma->lock);
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800174 return anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175out:
176 rcu_read_unlock();
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800177 return NULL;
178}
179
180static void page_unlock_anon_vma(struct anon_vma *anon_vma)
181{
182 spin_unlock(&anon_vma->lock);
183 rcu_read_unlock();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184}
185
186/*
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800187 * At what user virtual address is page expected in @vma?
188 * Returns virtual address or -EFAULT if page's index/offset is not
189 * within the range mapped the @vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 */
191static inline unsigned long
192vma_address(struct page *page, struct vm_area_struct *vma)
193{
194 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
195 unsigned long address;
196
197 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
198 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800199 /* page should be within @vma mapping range */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 return -EFAULT;
201 }
202 return address;
203}
204
205/*
206 * At what user virtual address is page expected in vma? checking that the
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800207 * page matches the vma: currently only used on anon pages, by unuse_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 */
209unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
210{
211 if (PageAnon(page)) {
212 if ((void *)vma->anon_vma !=
213 (void *)page->mapping - PAGE_MAPPING_ANON)
214 return -EFAULT;
215 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800216 if (!vma->vm_file ||
217 vma->vm_file->f_mapping != page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 return -EFAULT;
219 } else
220 return -EFAULT;
221 return vma_address(page, vma);
222}
223
224/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700225 * Check that @page is mapped at @address into @mm.
226 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700227 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700228 */
Carsten Otteceffc072005-06-23 22:05:25 -0700229pte_t *page_check_address(struct page *page, struct mm_struct *mm,
Hugh Dickinsc0718802005-10-29 18:16:31 -0700230 unsigned long address, spinlock_t **ptlp)
Nikita Danilov81b40822005-05-01 08:58:36 -0700231{
232 pgd_t *pgd;
233 pud_t *pud;
234 pmd_t *pmd;
235 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700236 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700237
Nikita Danilov81b40822005-05-01 08:58:36 -0700238 pgd = pgd_offset(mm, address);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700239 if (!pgd_present(*pgd))
240 return NULL;
241
242 pud = pud_offset(pgd, address);
243 if (!pud_present(*pud))
244 return NULL;
245
246 pmd = pmd_offset(pud, address);
247 if (!pmd_present(*pmd))
248 return NULL;
249
250 pte = pte_offset_map(pmd, address);
251 /* Make a quick check before getting the lock */
252 if (!pte_present(*pte)) {
253 pte_unmap(pte);
254 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700255 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700256
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700257 ptl = pte_lockptr(mm, pmd);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700258 spin_lock(ptl);
259 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
260 *ptlp = ptl;
261 return pte;
262 }
263 pte_unmap_unlock(pte, ptl);
264 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700265}
266
267/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700268 * Subfunctions of page_referenced: page_referenced_one called
269 * repeatedly from either page_referenced_anon or page_referenced_file.
270 */
271static int page_referenced_one(struct page *page,
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800272 struct vm_area_struct *vma, unsigned int *mapcount)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273{
274 struct mm_struct *mm = vma->vm_mm;
275 unsigned long address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700277 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 int referenced = 0;
279
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280 address = vma_address(page, vma);
281 if (address == -EFAULT)
282 goto out;
283
Hugh Dickinsc0718802005-10-29 18:16:31 -0700284 pte = page_check_address(page, mm, address, &ptl);
285 if (!pte)
286 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287
Hugh Dickins5a9bbdc2008-02-04 22:29:23 -0800288 if (vma->vm_flags & VM_LOCKED) {
289 referenced++;
290 *mapcount = 1; /* break early from loop */
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700291 } else if (ptep_clear_flush_young_notify(vma, address, pte))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700292 referenced++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
Hugh Dickinsc0718802005-10-29 18:16:31 -0700294 /* Pretend the page is referenced if the task has the
295 swap token and is in the middle of a page fault. */
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800296 if (mm != current->mm && has_swap_token(mm) &&
Hugh Dickinsc0718802005-10-29 18:16:31 -0700297 rwsem_is_locked(&mm->mmap_sem))
298 referenced++;
299
300 (*mapcount)--;
301 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700302out:
303 return referenced;
304}
305
Balbir Singhbed71612008-02-07 00:14:01 -0800306static int page_referenced_anon(struct page *page,
307 struct mem_cgroup *mem_cont)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308{
309 unsigned int mapcount;
310 struct anon_vma *anon_vma;
311 struct vm_area_struct *vma;
312 int referenced = 0;
313
314 anon_vma = page_lock_anon_vma(page);
315 if (!anon_vma)
316 return referenced;
317
318 mapcount = page_mapcount(page);
319 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
Balbir Singhbed71612008-02-07 00:14:01 -0800320 /*
321 * If we are reclaiming on behalf of a cgroup, skip
322 * counting on behalf of references from different
323 * cgroups
324 */
Hugh Dickinsbd845e32008-03-04 14:29:01 -0800325 if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
Balbir Singhbed71612008-02-07 00:14:01 -0800326 continue;
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800327 referenced += page_referenced_one(page, vma, &mapcount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328 if (!mapcount)
329 break;
330 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800331
332 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 return referenced;
334}
335
336/**
337 * page_referenced_file - referenced check for object-based rmap
338 * @page: the page we're checking references on.
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700339 * @mem_cont: target memory controller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 *
341 * For an object-based mapped page, find all the places it is mapped and
342 * check/clear the referenced flag. This is done by following the page->mapping
343 * pointer, then walking the chain of vmas it holds. It returns the number
344 * of references it found.
345 *
346 * This function is only called from page_referenced for object-based pages.
347 */
Balbir Singhbed71612008-02-07 00:14:01 -0800348static int page_referenced_file(struct page *page,
349 struct mem_cgroup *mem_cont)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700350{
351 unsigned int mapcount;
352 struct address_space *mapping = page->mapping;
353 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
354 struct vm_area_struct *vma;
355 struct prio_tree_iter iter;
356 int referenced = 0;
357
358 /*
359 * The caller's checks on page->mapping and !PageAnon have made
360 * sure that this is a file page: the check for page->mapping
361 * excludes the case just before it gets set on an anon page.
362 */
363 BUG_ON(PageAnon(page));
364
365 /*
366 * The page lock not only makes sure that page->mapping cannot
367 * suddenly be NULLified by truncation, it makes sure that the
368 * structure at mapping cannot be freed and reused yet,
369 * so we can safely take mapping->i_mmap_lock.
370 */
371 BUG_ON(!PageLocked(page));
372
373 spin_lock(&mapping->i_mmap_lock);
374
375 /*
376 * i_mmap_lock does not stabilize mapcount at all, but mapcount
377 * is more likely to be accurate if we note it after spinning.
378 */
379 mapcount = page_mapcount(page);
380
381 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Balbir Singhbed71612008-02-07 00:14:01 -0800382 /*
383 * If we are reclaiming on behalf of a cgroup, skip
384 * counting on behalf of references from different
385 * cgroups
386 */
Hugh Dickinsbd845e32008-03-04 14:29:01 -0800387 if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
Balbir Singhbed71612008-02-07 00:14:01 -0800388 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700389 if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE))
390 == (VM_LOCKED|VM_MAYSHARE)) {
391 referenced++;
392 break;
393 }
Rik van Rielf7b7fd82005-11-28 13:44:07 -0800394 referenced += page_referenced_one(page, vma, &mapcount);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700395 if (!mapcount)
396 break;
397 }
398
399 spin_unlock(&mapping->i_mmap_lock);
400 return referenced;
401}
402
403/**
404 * page_referenced - test if the page was referenced
405 * @page: the page to test
406 * @is_locked: caller holds lock on the page
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700407 * @mem_cont: target memory controller
Linus Torvalds1da177e2005-04-16 15:20:36 -0700408 *
409 * Quick test_and_clear_referenced for all mappings to a page,
410 * returns the number of ptes which referenced the page.
411 */
Balbir Singhbed71612008-02-07 00:14:01 -0800412int page_referenced(struct page *page, int is_locked,
413 struct mem_cgroup *mem_cont)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414{
415 int referenced = 0;
416
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 if (TestClearPageReferenced(page))
418 referenced++;
419
420 if (page_mapped(page) && page->mapping) {
421 if (PageAnon(page))
Balbir Singhbed71612008-02-07 00:14:01 -0800422 referenced += page_referenced_anon(page, mem_cont);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423 else if (is_locked)
Balbir Singhbed71612008-02-07 00:14:01 -0800424 referenced += page_referenced_file(page, mem_cont);
Nick Piggin529ae9a2008-08-02 12:01:03 +0200425 else if (!trylock_page(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 referenced++;
427 else {
428 if (page->mapping)
Balbir Singhbed71612008-02-07 00:14:01 -0800429 referenced +=
430 page_referenced_file(page, mem_cont);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700431 unlock_page(page);
432 }
433 }
Christian Borntraeger5b7baf02008-03-25 18:47:12 +0100434
435 if (page_test_and_clear_young(page))
436 referenced++;
437
Linus Torvalds1da177e2005-04-16 15:20:36 -0700438 return referenced;
439}
440
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700441static int page_mkclean_one(struct page *page, struct vm_area_struct *vma)
442{
443 struct mm_struct *mm = vma->vm_mm;
444 unsigned long address;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100445 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700446 spinlock_t *ptl;
447 int ret = 0;
448
449 address = vma_address(page, vma);
450 if (address == -EFAULT)
451 goto out;
452
453 pte = page_check_address(page, mm, address, &ptl);
454 if (!pte)
455 goto out;
456
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100457 if (pte_dirty(*pte) || pte_write(*pte)) {
458 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700459
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100460 flush_cache_page(vma, address, pte_pfn(*pte));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700461 entry = ptep_clear_flush_notify(vma, address, pte);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100462 entry = pte_wrprotect(entry);
463 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -0800464 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100465 ret = 1;
466 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700467
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700468 pte_unmap_unlock(pte, ptl);
469out:
470 return ret;
471}
472
473static int page_mkclean_file(struct address_space *mapping, struct page *page)
474{
475 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
476 struct vm_area_struct *vma;
477 struct prio_tree_iter iter;
478 int ret = 0;
479
480 BUG_ON(PageAnon(page));
481
482 spin_lock(&mapping->i_mmap_lock);
483 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
484 if (vma->vm_flags & VM_SHARED)
485 ret += page_mkclean_one(page, vma);
486 }
487 spin_unlock(&mapping->i_mmap_lock);
488 return ret;
489}
490
491int page_mkclean(struct page *page)
492{
493 int ret = 0;
494
495 BUG_ON(!PageLocked(page));
496
497 if (page_mapped(page)) {
498 struct address_space *mapping = page_mapping(page);
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100499 if (mapping) {
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700500 ret = page_mkclean_file(mapping, page);
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100501 if (page_test_dirty(page)) {
502 page_clear_dirty(page);
503 ret = 1;
504 }
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200505 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700506 }
507
508 return ret;
509}
Jaya Kumar60b59be2007-05-08 00:37:37 -0700510EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700511
Linus Torvalds1da177e2005-04-16 15:20:36 -0700512/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700513 * __page_set_anon_rmap - setup new anonymous rmap
Nick Piggin9617d952006-01-06 00:11:12 -0800514 * @page: the page to add the mapping to
515 * @vma: the vm area in which the mapping is added
516 * @address: the user virtual address mapped
517 */
518static void __page_set_anon_rmap(struct page *page,
519 struct vm_area_struct *vma, unsigned long address)
520{
521 struct anon_vma *anon_vma = vma->anon_vma;
522
523 BUG_ON(!anon_vma);
524 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
525 page->mapping = (struct address_space *) anon_vma;
526
527 page->index = linear_page_index(vma, address);
528
Nick Piggina74609f2006-01-06 00:11:20 -0800529 /*
530 * nr_mapped state can be updated without turning off
531 * interrupts because it is not modified via interrupt.
532 */
Christoph Lameterf3dbd342006-06-30 01:55:36 -0700533 __inc_zone_page_state(page, NR_ANON_PAGES);
Nick Piggin9617d952006-01-06 00:11:12 -0800534}
535
536/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700537 * __page_check_anon_rmap - sanity check anonymous rmap addition
Nick Pigginc97a9e12007-05-16 22:11:21 -0700538 * @page: the page to add the mapping to
539 * @vma: the vm area in which the mapping is added
540 * @address: the user virtual address mapped
541 */
542static void __page_check_anon_rmap(struct page *page,
543 struct vm_area_struct *vma, unsigned long address)
544{
545#ifdef CONFIG_DEBUG_VM
546 /*
547 * The page's anon-rmap details (mapping and index) are guaranteed to
548 * be set up correctly at this point.
549 *
550 * We have exclusion against page_add_anon_rmap because the caller
551 * always holds the page locked, except if called from page_dup_rmap,
552 * in which case the page is already known to be setup.
553 *
554 * We have exclusion against page_add_new_anon_rmap because those pages
555 * are initially only visible via the pagetables, and the pte is locked
556 * over the call to page_add_new_anon_rmap.
557 */
558 struct anon_vma *anon_vma = vma->anon_vma;
559 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
560 BUG_ON(page->mapping != (struct address_space *)anon_vma);
561 BUG_ON(page->index != linear_page_index(vma, address));
562#endif
563}
564
565/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700566 * page_add_anon_rmap - add pte mapping to an anonymous page
567 * @page: the page to add the mapping to
568 * @vma: the vm area in which the mapping is added
569 * @address: the user virtual address mapped
570 *
Nick Pigginc97a9e12007-05-16 22:11:21 -0700571 * The caller needs to hold the pte lock and the page must be locked.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700572 */
573void page_add_anon_rmap(struct page *page,
574 struct vm_area_struct *vma, unsigned long address)
575{
Nick Pigginc97a9e12007-05-16 22:11:21 -0700576 VM_BUG_ON(!PageLocked(page));
577 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Nick Piggin9617d952006-01-06 00:11:12 -0800578 if (atomic_inc_and_test(&page->_mapcount))
579 __page_set_anon_rmap(page, vma, address);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -0700580 else
Nick Pigginc97a9e12007-05-16 22:11:21 -0700581 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700582}
583
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700584/**
Nick Piggin9617d952006-01-06 00:11:12 -0800585 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
586 * @page: the page to add the mapping to
587 * @vma: the vm area in which the mapping is added
588 * @address: the user virtual address mapped
589 *
590 * Same as page_add_anon_rmap but must only be called on *new* pages.
591 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -0700592 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -0800593 */
594void page_add_new_anon_rmap(struct page *page,
595 struct vm_area_struct *vma, unsigned long address)
596{
Nick Pigginc97a9e12007-05-16 22:11:21 -0700597 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Nick Piggin9617d952006-01-06 00:11:12 -0800598 atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */
599 __page_set_anon_rmap(page, vma, address);
600}
601
Linus Torvalds1da177e2005-04-16 15:20:36 -0700602/**
603 * page_add_file_rmap - add pte mapping to a file page
604 * @page: the page to add the mapping to
605 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700606 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700607 */
608void page_add_file_rmap(struct page *page)
609{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700610 if (atomic_inc_and_test(&page->_mapcount))
Christoph Lameter65ba55f2006-06-30 01:55:34 -0700611 __inc_zone_page_state(page, NR_FILE_MAPPED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700612}
613
Nick Pigginc97a9e12007-05-16 22:11:21 -0700614#ifdef CONFIG_DEBUG_VM
615/**
616 * page_dup_rmap - duplicate pte mapping to a page
617 * @page: the page to add the mapping to
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700618 * @vma: the vm area being duplicated
619 * @address: the user virtual address mapped
Nick Pigginc97a9e12007-05-16 22:11:21 -0700620 *
621 * For copy_page_range only: minimal extract from page_add_file_rmap /
622 * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's
623 * quicker.
624 *
625 * The caller needs to hold the pte lock.
626 */
627void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address)
628{
629 BUG_ON(page_mapcount(page) == 0);
630 if (PageAnon(page))
631 __page_check_anon_rmap(page, vma, address);
632 atomic_inc(&page->_mapcount);
633}
634#endif
635
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636/**
637 * page_remove_rmap - take down pte mapping from a page
638 * @page: page to remove mapping from
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700639 * @vma: the vm area in which the mapping is removed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700640 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700641 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700642 */
Nick Piggin7de6b802006-12-22 01:09:33 -0800643void page_remove_rmap(struct page *page, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700644{
Linus Torvalds1da177e2005-04-16 15:20:36 -0700645 if (atomic_add_negative(-1, &page->_mapcount)) {
Nick Pigginb7ab7952006-03-22 00:08:42 -0800646 if (unlikely(page_mapcount(page) < 0)) {
Dave Jonesef2bf0d2006-01-08 01:01:00 -0800647 printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page));
Nick Piggin7de6b802006-12-22 01:09:33 -0800648 printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(page));
Dave Jonesef2bf0d2006-01-08 01:01:00 -0800649 printk (KERN_EMERG " page->flags = %lx\n", page->flags);
650 printk (KERN_EMERG " page->count = %x\n", page_count(page));
651 printk (KERN_EMERG " page->mapping = %p\n", page->mapping);
Nick Piggin7de6b802006-12-22 01:09:33 -0800652 print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops);
Nick Piggin54cb8822007-07-19 01:46:59 -0700653 if (vma->vm_ops) {
Nick Piggin54cb8822007-07-19 01:46:59 -0700654 print_symbol (KERN_EMERG " vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault);
655 }
Nick Piggin7de6b802006-12-22 01:09:33 -0800656 if (vma->vm_file && vma->vm_file->f_op)
657 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 -0700658 BUG();
Dave Jonesef2bf0d2006-01-08 01:01:00 -0800659 }
Dave Jonesb16bc642006-10-11 01:21:27 -0700660
Linus Torvalds1da177e2005-04-16 15:20:36 -0700661 /*
662 * It would be tidy to reset the PageAnon mapping here,
663 * but that might overwrite a racing page_add_anon_rmap
664 * which increments mapcount after us but sets mapping
665 * before us: so leave the reset to free_hot_cold_page,
666 * and remember that it's only reliable while mapped.
667 * Leaving it set also helps swapoff to reinstate ptes
668 * faster for those pages still in swapcache.
669 */
Martin Schwidefskya4b526b2008-08-01 16:39:12 +0200670 if ((!PageAnon(page) || PageSwapCache(page)) &&
671 page_test_dirty(page)) {
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200672 page_clear_dirty(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700673 set_page_dirty(page);
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200674 }
Balbir Singh8a9f3cc2008-02-07 00:13:53 -0800675 mem_cgroup_uncharge_page(page);
676
Christoph Lameterf3dbd342006-06-30 01:55:36 -0700677 __dec_zone_page_state(page,
678 PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 }
680}
681
682/*
683 * Subfunctions of try_to_unmap: try_to_unmap_one called
684 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
685 */
Christoph Lametera48d07a2006-02-01 03:05:38 -0800686static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
Christoph Lameter73523492006-06-23 02:03:27 -0700687 int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700688{
689 struct mm_struct *mm = vma->vm_mm;
690 unsigned long address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691 pte_t *pte;
692 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700693 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700694 int ret = SWAP_AGAIN;
695
Linus Torvalds1da177e2005-04-16 15:20:36 -0700696 address = vma_address(page, vma);
697 if (address == -EFAULT)
698 goto out;
699
Hugh Dickinsc0718802005-10-29 18:16:31 -0700700 pte = page_check_address(page, mm, address, &ptl);
701 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -0700702 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703
704 /*
705 * If the page is mlock()d, we cannot swap it out.
706 * If it's recently referenced (perhaps page_referenced
707 * skipped over this mm) then we should reactivate it.
708 */
Christoph Lametere6a15302006-06-25 05:46:49 -0700709 if (!migration && ((vma->vm_flags & VM_LOCKED) ||
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700710 (ptep_clear_flush_young_notify(vma, address, pte)))) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700711 ret = SWAP_FAIL;
712 goto out_unmap;
713 }
714
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715 /* Nuke the page table entry. */
716 flush_cache_page(vma, address, page_to_pfn(page));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700717 pteval = ptep_clear_flush_notify(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700718
719 /* Move the dirty bit to the physical page now the pte is gone. */
720 if (pte_dirty(pteval))
721 set_page_dirty(page);
722
Hugh Dickins365e9c872005-10-29 18:16:18 -0700723 /* Update high watermark before we lower rss */
724 update_hiwater_rss(mm);
725
Linus Torvalds1da177e2005-04-16 15:20:36 -0700726 if (PageAnon(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700727 swp_entry_t entry = { .val = page_private(page) };
Christoph Lameter06972122006-06-23 02:03:35 -0700728
729 if (PageSwapCache(page)) {
730 /*
731 * Store the swap location in the pte.
732 * See handle_pte_fault() ...
733 */
734 swap_duplicate(entry);
735 if (list_empty(&mm->mmlist)) {
736 spin_lock(&mmlist_lock);
737 if (list_empty(&mm->mmlist))
738 list_add(&mm->mmlist, &init_mm.mmlist);
739 spin_unlock(&mmlist_lock);
740 }
Christoph Lameter442c9132006-06-23 02:03:38 -0700741 dec_mm_counter(mm, anon_rss);
Christoph Lameter04e62a22006-06-23 02:03:38 -0700742#ifdef CONFIG_MIGRATION
Christoph Lameter06972122006-06-23 02:03:35 -0700743 } else {
744 /*
745 * Store the pfn of the page in a special migration
746 * pte. do_swap_page() will wait until the migration
747 * pte is removed and then restart fault handling.
748 */
749 BUG_ON(!migration);
750 entry = make_migration_entry(page, pte_write(pteval));
Christoph Lameter04e62a22006-06-23 02:03:38 -0700751#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 }
753 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
754 BUG_ON(pte_file(*pte));
Hugh Dickins42946212005-10-29 18:16:05 -0700755 } else
Christoph Lameter04e62a22006-06-23 02:03:38 -0700756#ifdef CONFIG_MIGRATION
757 if (migration) {
758 /* Establish migration entry for a file page */
759 swp_entry_t entry;
760 entry = make_migration_entry(page, pte_write(pteval));
761 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
762 } else
763#endif
Hugh Dickins42946212005-10-29 18:16:05 -0700764 dec_mm_counter(mm, file_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765
Christoph Lameter04e62a22006-06-23 02:03:38 -0700766
Nick Piggin7de6b802006-12-22 01:09:33 -0800767 page_remove_rmap(page, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700768 page_cache_release(page);
769
770out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700771 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700772out:
773 return ret;
774}
775
776/*
777 * objrmap doesn't work for nonlinear VMAs because the assumption that
778 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
779 * Consequently, given a particular page and its ->index, we cannot locate the
780 * ptes which are mapping that page without an exhaustive linear search.
781 *
782 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
783 * maps the file to which the target page belongs. The ->vm_private_data field
784 * holds the current cursor into that scan. Successive searches will circulate
785 * around the vma's virtual address space.
786 *
787 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
788 * more scanning pressure is placed against them as well. Eventually pages
789 * will become fully unmapped and are eligible for eviction.
790 *
791 * For very sparsely populated VMAs this is a little inefficient - chances are
792 * there there won't be many ptes located within the scan cluster. In this case
793 * maybe we could scan further - to the end of the pte page, perhaps.
794 */
795#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
796#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
797
798static void try_to_unmap_cluster(unsigned long cursor,
799 unsigned int *mapcount, struct vm_area_struct *vma)
800{
801 struct mm_struct *mm = vma->vm_mm;
802 pgd_t *pgd;
803 pud_t *pud;
804 pmd_t *pmd;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700805 pte_t *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700807 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 struct page *page;
809 unsigned long address;
810 unsigned long end;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700811
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812 address = (vma->vm_start + cursor) & CLUSTER_MASK;
813 end = address + CLUSTER_SIZE;
814 if (address < vma->vm_start)
815 address = vma->vm_start;
816 if (end > vma->vm_end)
817 end = vma->vm_end;
818
819 pgd = pgd_offset(mm, address);
820 if (!pgd_present(*pgd))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700821 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822
823 pud = pud_offset(pgd, address);
824 if (!pud_present(*pud))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700825 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700826
827 pmd = pmd_offset(pud, address);
828 if (!pmd_present(*pmd))
Hugh Dickinsc0718802005-10-29 18:16:31 -0700829 return;
830
831 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832
Hugh Dickins365e9c872005-10-29 18:16:18 -0700833 /* Update high watermark before we lower rss */
834 update_hiwater_rss(mm);
835
Hugh Dickinsc0718802005-10-29 18:16:31 -0700836 for (; address < end; pte++, address += PAGE_SIZE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700837 if (!pte_present(*pte))
838 continue;
Linus Torvalds6aab3412005-11-28 14:34:23 -0800839 page = vm_normal_page(vma, address, *pte);
840 BUG_ON(!page || PageAnon(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700841
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700842 if (ptep_clear_flush_young_notify(vma, address, pte))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843 continue;
844
845 /* Nuke the page table entry. */
Ben Collinseca35132005-11-29 11:45:26 -0800846 flush_cache_page(vma, address, pte_pfn(*pte));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700847 pteval = ptep_clear_flush_notify(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700848
849 /* If nonlinear, store the file page offset in the pte. */
850 if (page->index != linear_page_index(vma, address))
851 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
852
853 /* Move the dirty bit to the physical page now the pte is gone. */
854 if (pte_dirty(pteval))
855 set_page_dirty(page);
856
Nick Piggin7de6b802006-12-22 01:09:33 -0800857 page_remove_rmap(page, vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858 page_cache_release(page);
Hugh Dickins42946212005-10-29 18:16:05 -0700859 dec_mm_counter(mm, file_rss);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700860 (*mapcount)--;
861 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700862 pte_unmap_unlock(pte - 1, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863}
864
Christoph Lameter73523492006-06-23 02:03:27 -0700865static int try_to_unmap_anon(struct page *page, int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700866{
867 struct anon_vma *anon_vma;
868 struct vm_area_struct *vma;
869 int ret = SWAP_AGAIN;
870
871 anon_vma = page_lock_anon_vma(page);
872 if (!anon_vma)
873 return ret;
874
875 list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
Christoph Lameter73523492006-06-23 02:03:27 -0700876 ret = try_to_unmap_one(page, vma, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700877 if (ret == SWAP_FAIL || !page_mapped(page))
878 break;
879 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800880
881 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700882 return ret;
883}
884
885/**
886 * try_to_unmap_file - unmap file page using the object-based rmap method
887 * @page: the page to unmap
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700888 * @migration: migration flag
Linus Torvalds1da177e2005-04-16 15:20:36 -0700889 *
890 * Find all the mappings of a page using the mapping pointer and the vma chains
891 * contained in the address_space struct it points to.
892 *
893 * This function is only called from try_to_unmap for object-based pages.
894 */
Christoph Lameter73523492006-06-23 02:03:27 -0700895static int try_to_unmap_file(struct page *page, int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700896{
897 struct address_space *mapping = page->mapping;
898 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
899 struct vm_area_struct *vma;
900 struct prio_tree_iter iter;
901 int ret = SWAP_AGAIN;
902 unsigned long cursor;
903 unsigned long max_nl_cursor = 0;
904 unsigned long max_nl_size = 0;
905 unsigned int mapcount;
906
907 spin_lock(&mapping->i_mmap_lock);
908 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Christoph Lameter73523492006-06-23 02:03:27 -0700909 ret = try_to_unmap_one(page, vma, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910 if (ret == SWAP_FAIL || !page_mapped(page))
911 goto out;
912 }
913
914 if (list_empty(&mapping->i_mmap_nonlinear))
915 goto out;
916
917 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
918 shared.vm_set.list) {
Christoph Lametere6a15302006-06-25 05:46:49 -0700919 if ((vma->vm_flags & VM_LOCKED) && !migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700920 continue;
921 cursor = (unsigned long) vma->vm_private_data;
922 if (cursor > max_nl_cursor)
923 max_nl_cursor = cursor;
924 cursor = vma->vm_end - vma->vm_start;
925 if (cursor > max_nl_size)
926 max_nl_size = cursor;
927 }
928
929 if (max_nl_size == 0) { /* any nonlinears locked or reserved */
930 ret = SWAP_FAIL;
931 goto out;
932 }
933
934 /*
935 * We don't try to search for this page in the nonlinear vmas,
936 * and page_referenced wouldn't have found it anyway. Instead
937 * just walk the nonlinear vmas trying to age and unmap some.
938 * The mapcount of the page we came in with is irrelevant,
939 * but even so use it as a guide to how hard we should try?
940 */
941 mapcount = page_mapcount(page);
942 if (!mapcount)
943 goto out;
944 cond_resched_lock(&mapping->i_mmap_lock);
945
946 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
947 if (max_nl_cursor == 0)
948 max_nl_cursor = CLUSTER_SIZE;
949
950 do {
951 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
952 shared.vm_set.list) {
Christoph Lametere6a15302006-06-25 05:46:49 -0700953 if ((vma->vm_flags & VM_LOCKED) && !migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700954 continue;
955 cursor = (unsigned long) vma->vm_private_data;
Hugh Dickins839b9682005-09-03 15:54:43 -0700956 while ( cursor < max_nl_cursor &&
Linus Torvalds1da177e2005-04-16 15:20:36 -0700957 cursor < vma->vm_end - vma->vm_start) {
958 try_to_unmap_cluster(cursor, &mapcount, vma);
959 cursor += CLUSTER_SIZE;
960 vma->vm_private_data = (void *) cursor;
961 if ((int)mapcount <= 0)
962 goto out;
963 }
964 vma->vm_private_data = (void *) max_nl_cursor;
965 }
966 cond_resched_lock(&mapping->i_mmap_lock);
967 max_nl_cursor += CLUSTER_SIZE;
968 } while (max_nl_cursor <= max_nl_size);
969
970 /*
971 * Don't loop forever (perhaps all the remaining pages are
972 * in locked vmas). Reset cursor on all unreserved nonlinear
973 * vmas, now forgetting on which ones it had fallen behind.
974 */
Hugh Dickins101d2be2005-11-21 21:32:16 -0800975 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
976 vma->vm_private_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700977out:
978 spin_unlock(&mapping->i_mmap_lock);
979 return ret;
980}
981
982/**
983 * try_to_unmap - try to remove all page table mappings to a page
984 * @page: the page to get unmapped
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700985 * @migration: migration flag
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986 *
987 * Tries to remove all the page table entries which are mapping this
988 * page, used in the pageout path. Caller must hold the page lock.
989 * Return values are:
990 *
991 * SWAP_SUCCESS - we succeeded in removing all mappings
992 * SWAP_AGAIN - we missed a mapping, try again later
993 * SWAP_FAIL - the page is unswappable
994 */
Christoph Lameter73523492006-06-23 02:03:27 -0700995int try_to_unmap(struct page *page, int migration)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700996{
997 int ret;
998
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999 BUG_ON(!PageLocked(page));
1000
1001 if (PageAnon(page))
Christoph Lameter73523492006-06-23 02:03:27 -07001002 ret = try_to_unmap_anon(page, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001003 else
Christoph Lameter73523492006-06-23 02:03:27 -07001004 ret = try_to_unmap_file(page, migration);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001005
1006 if (!page_mapped(page))
1007 ret = SWAP_SUCCESS;
1008 return ret;
1009}
Nikita Danilov81b40822005-05-01 08:58:36 -07001010