blob: 0eb463ea88dd71326b70342f8492df873a6b5df1 [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
Hugh Dickins98f32602009-05-21 20:33:58 +010017 * Contributions by Hugh Dickins 2003, 2004
Linus Torvalds1da177e2005-04-16 15:20:36 -070018 */
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)
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070027 * mapping->i_mmap_mutex
Peter Zijlstra2b575eb2011-05-24 17:12:11 -070028 * anon_vma->mutex
Nick Piggin82591e62006-10-19 23:29:10 -070029 * 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)
Dave Chinner250df6e2011-03-22 22:23:36 +110034 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
Dave Chinnera66979a2011-03-22 22:23:41 +110035 * inode_wb_list_lock (in set_page_dirty's __mark_inode_dirty)
Nick Piggin82591e62006-10-19 23:29:10 -070036 * sb_lock (within inode_lock in fs/fs-writeback.c)
37 * mapping->tree_lock (widely used, in set_page_dirty,
38 * in arch-dependent flush_dcache_mmap_lock,
Dave Chinnera66979a2011-03-22 22:23:41 +110039 * within inode_wb_list_lock in __sync_single_inode)
Andi Kleen6a460792009-09-16 11:50:15 +020040 *
41 * (code doesn't rely on that order so it could be switched around)
42 * ->tasklist_lock
Peter Zijlstra2b575eb2011-05-24 17:12:11 -070043 * anon_vma->mutex (memory_failure, collect_procs_anon)
Andi Kleen6a460792009-09-16 11:50:15 +020044 * pte map lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 */
46
47#include <linux/mm.h>
48#include <linux/pagemap.h>
49#include <linux/swap.h>
50#include <linux/swapops.h>
51#include <linux/slab.h>
52#include <linux/init.h>
Hugh Dickins5ad64682009-12-14 17:59:24 -080053#include <linux/ksm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070054#include <linux/rmap.h>
55#include <linux/rcupdate.h>
Christoph Lametera48d07a2006-02-01 03:05:38 -080056#include <linux/module.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080057#include <linux/memcontrol.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070058#include <linux/mmu_notifier.h>
KOSAKI Motohiro64cdd542009-01-06 14:39:16 -080059#include <linux/migrate.h>
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +090060#include <linux/hugetlb.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070061
62#include <asm/tlbflush.h>
63
Nick Pigginb291f002008-10-18 20:26:44 -070064#include "internal.h"
65
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070066static struct kmem_cache *anon_vma_cachep;
Rik van Riel5beb4932010-03-05 13:42:07 -080067static struct kmem_cache *anon_vma_chain_cachep;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070068
69static inline struct anon_vma *anon_vma_alloc(void)
70{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070071 struct anon_vma *anon_vma;
72
73 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
74 if (anon_vma) {
75 atomic_set(&anon_vma->refcount, 1);
76 /*
77 * Initialise the anon_vma root to point to itself. If called
78 * from fork, the root will be reset to the parents anon_vma.
79 */
80 anon_vma->root = anon_vma;
81 }
82
83 return anon_vma;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070084}
85
Peter Zijlstra01d8b202011-03-22 16:32:49 -070086static inline void anon_vma_free(struct anon_vma *anon_vma)
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070087{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070088 VM_BUG_ON(atomic_read(&anon_vma->refcount));
Peter Zijlstra88c22082011-05-24 17:12:13 -070089
90 /*
91 * Synchronize against page_lock_anon_vma() such that
92 * we can safely hold the lock without the anon_vma getting
93 * freed.
94 *
95 * Relies on the full mb implied by the atomic_dec_and_test() from
96 * put_anon_vma() against the acquire barrier implied by
97 * mutex_trylock() from page_lock_anon_vma(). This orders:
98 *
99 * page_lock_anon_vma() VS put_anon_vma()
100 * mutex_trylock() atomic_dec_and_test()
101 * LOCK MB
102 * atomic_read() mutex_is_locked()
103 *
104 * LOCK should suffice since the actual taking of the lock must
105 * happen _before_ what follows.
106 */
107 if (mutex_is_locked(&anon_vma->root->mutex)) {
108 anon_vma_lock(anon_vma);
109 anon_vma_unlock(anon_vma);
110 }
111
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -0700112 kmem_cache_free(anon_vma_cachep, anon_vma);
113}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700114
Rik van Riel5beb4932010-03-05 13:42:07 -0800115static inline struct anon_vma_chain *anon_vma_chain_alloc(void)
116{
117 return kmem_cache_alloc(anon_vma_chain_cachep, GFP_KERNEL);
118}
119
Namhyung Kime574b5f2010-10-26 14:22:02 -0700120static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
Rik van Riel5beb4932010-03-05 13:42:07 -0800121{
122 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
123}
124
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700125/**
126 * anon_vma_prepare - attach an anon_vma to a memory region
127 * @vma: the memory region in question
128 *
129 * This makes sure the memory mapping described by 'vma' has
130 * an 'anon_vma' attached to it, so that we can associate the
131 * anonymous pages mapped into it with that anon_vma.
132 *
133 * The common case will be that we already have one, but if
Figo.zhang23a07902010-12-27 15:14:06 +0100134 * not we either need to find an adjacent mapping that we
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700135 * can re-use the anon_vma from (very common when the only
136 * reason for splitting a vma has been mprotect()), or we
137 * allocate a new one.
138 *
139 * Anon-vma allocations are very subtle, because we may have
140 * optimistically looked up an anon_vma in page_lock_anon_vma()
141 * and that may actually touch the spinlock even in the newly
142 * allocated vma (it depends on RCU to make sure that the
143 * anon_vma isn't actually destroyed).
144 *
145 * As a result, we need to do proper anon_vma locking even
146 * for the new allocation. At the same time, we do not want
147 * to do any locking for the common case of already having
148 * an anon_vma.
149 *
150 * This must be called with the mmap_sem held for reading.
151 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152int anon_vma_prepare(struct vm_area_struct *vma)
153{
154 struct anon_vma *anon_vma = vma->anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800155 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156
157 might_sleep();
158 if (unlikely(!anon_vma)) {
159 struct mm_struct *mm = vma->vm_mm;
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700160 struct anon_vma *allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161
Rik van Riel5beb4932010-03-05 13:42:07 -0800162 avc = anon_vma_chain_alloc();
163 if (!avc)
164 goto out_enomem;
165
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 anon_vma = find_mergeable_anon_vma(vma);
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700167 allocated = NULL;
168 if (!anon_vma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169 anon_vma = anon_vma_alloc();
170 if (unlikely(!anon_vma))
Rik van Riel5beb4932010-03-05 13:42:07 -0800171 goto out_enomem_free_avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700172 allocated = anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700173 }
174
Rik van Rielcba48b92010-08-09 17:18:38 -0700175 anon_vma_lock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176 /* page_table_lock to protect against threads */
177 spin_lock(&mm->page_table_lock);
178 if (likely(!vma->anon_vma)) {
179 vma->anon_vma = anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800180 avc->anon_vma = anon_vma;
181 avc->vma = vma;
182 list_add(&avc->same_vma, &vma->anon_vma_chain);
Andrea Arcangeli26ba0cb2010-08-09 17:19:08 -0700183 list_add_tail(&avc->same_anon_vma, &anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 allocated = NULL;
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400185 avc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 }
187 spin_unlock(&mm->page_table_lock);
Rik van Rielcba48b92010-08-09 17:18:38 -0700188 anon_vma_unlock(anon_vma);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400189
190 if (unlikely(allocated))
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700191 put_anon_vma(allocated);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400192 if (unlikely(avc))
Rik van Riel5beb4932010-03-05 13:42:07 -0800193 anon_vma_chain_free(avc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 }
195 return 0;
Rik van Riel5beb4932010-03-05 13:42:07 -0800196
197 out_enomem_free_avc:
198 anon_vma_chain_free(avc);
199 out_enomem:
200 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201}
202
Rik van Riel5beb4932010-03-05 13:42:07 -0800203static void anon_vma_chain_link(struct vm_area_struct *vma,
204 struct anon_vma_chain *avc,
205 struct anon_vma *anon_vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206{
Rik van Riel5beb4932010-03-05 13:42:07 -0800207 avc->vma = vma;
208 avc->anon_vma = anon_vma;
209 list_add(&avc->same_vma, &vma->anon_vma_chain);
210
Rik van Rielcba48b92010-08-09 17:18:38 -0700211 anon_vma_lock(anon_vma);
Andrea Arcangeli05759d32011-01-13 15:46:53 -0800212 /*
213 * It's critical to add new vmas to the tail of the anon_vma,
214 * see comment in huge_memory.c:__split_huge_page().
215 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800216 list_add_tail(&avc->same_anon_vma, &anon_vma->head);
Rik van Rielcba48b92010-08-09 17:18:38 -0700217 anon_vma_unlock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218}
219
Rik van Riel5beb4932010-03-05 13:42:07 -0800220/*
221 * Attach the anon_vmas from src to dst.
222 * Returns 0 on success, -ENOMEM on failure.
223 */
224int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225{
Rik van Riel5beb4932010-03-05 13:42:07 -0800226 struct anon_vma_chain *avc, *pavc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227
Linus Torvalds646d87b2010-04-11 17:15:03 -0700228 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
Rik van Riel5beb4932010-03-05 13:42:07 -0800229 avc = anon_vma_chain_alloc();
230 if (!avc)
231 goto enomem_failure;
232 anon_vma_chain_link(dst, avc, pavc->anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233 }
Rik van Riel5beb4932010-03-05 13:42:07 -0800234 return 0;
235
236 enomem_failure:
237 unlink_anon_vmas(dst);
238 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239}
240
Rik van Riel5beb4932010-03-05 13:42:07 -0800241/*
242 * Attach vma to its own anon_vma, as well as to the anon_vmas that
243 * the corresponding VMA in the parent process is attached to.
244 * Returns 0 on success, non-zero on failure.
245 */
246int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247{
Rik van Riel5beb4932010-03-05 13:42:07 -0800248 struct anon_vma_chain *avc;
249 struct anon_vma *anon_vma;
250
251 /* Don't bother if the parent process has no anon_vma here. */
252 if (!pvma->anon_vma)
253 return 0;
254
255 /*
256 * First, attach the new VMA to the parent VMA's anon_vmas,
257 * so rmap can find non-COWed pages in child processes.
258 */
259 if (anon_vma_clone(vma, pvma))
260 return -ENOMEM;
261
262 /* Then add our own anon_vma. */
263 anon_vma = anon_vma_alloc();
264 if (!anon_vma)
265 goto out_error;
266 avc = anon_vma_chain_alloc();
267 if (!avc)
268 goto out_error_free_anon_vma;
Rik van Riel5c341ee2010-08-09 17:18:39 -0700269
270 /*
271 * The root anon_vma's spinlock is the lock actually used when we
272 * lock any of the anon_vmas in this anon_vma tree.
273 */
274 anon_vma->root = pvma->anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -0700275 /*
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700276 * With refcounts, an anon_vma can stay around longer than the
277 * process it belongs to. The root anon_vma needs to be pinned until
278 * this anon_vma is freed, because the lock lives in the root.
Rik van Riel76545062010-08-09 17:18:41 -0700279 */
280 get_anon_vma(anon_vma->root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800281 /* Mark this anon_vma as the one where our new (COWed) pages go. */
282 vma->anon_vma = anon_vma;
Rik van Riel5c341ee2010-08-09 17:18:39 -0700283 anon_vma_chain_link(vma, avc, anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800284
285 return 0;
286
287 out_error_free_anon_vma:
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700288 put_anon_vma(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800289 out_error:
Rik van Riel4946d542010-04-05 12:13:33 -0400290 unlink_anon_vmas(vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800291 return -ENOMEM;
292}
293
294static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain)
295{
296 struct anon_vma *anon_vma = anon_vma_chain->anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700297 int empty;
298
Rik van Riel5beb4932010-03-05 13:42:07 -0800299 /* If anon_vma_fork fails, we can get an empty anon_vma_chain. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 if (!anon_vma)
301 return;
302
Rik van Rielcba48b92010-08-09 17:18:38 -0700303 anon_vma_lock(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800304 list_del(&anon_vma_chain->same_anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305
306 /* We must garbage collect the anon_vma if it's empty */
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700307 empty = list_empty(&anon_vma->head);
Rik van Rielcba48b92010-08-09 17:18:38 -0700308 anon_vma_unlock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700310 if (empty)
311 put_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700312}
313
Rik van Riel5beb4932010-03-05 13:42:07 -0800314void unlink_anon_vmas(struct vm_area_struct *vma)
315{
316 struct anon_vma_chain *avc, *next;
317
Rik van Riel5c341ee2010-08-09 17:18:39 -0700318 /*
319 * Unlink each anon_vma chained to the VMA. This list is ordered
320 * from newest to oldest, ensuring the root anon_vma gets freed last.
321 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800322 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
323 anon_vma_unlink(avc);
324 list_del(&avc->same_vma);
325 anon_vma_chain_free(avc);
326 }
327}
328
Alexey Dobriyan51cc5062008-07-25 19:45:34 -0700329static void anon_vma_ctor(void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700330{
Christoph Lametera35afb82007-05-16 22:10:57 -0700331 struct anon_vma *anon_vma = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700332
Peter Zijlstra2b575eb2011-05-24 17:12:11 -0700333 mutex_init(&anon_vma->mutex);
Peter Zijlstra83813262011-03-22 16:32:48 -0700334 atomic_set(&anon_vma->refcount, 0);
Christoph Lametera35afb82007-05-16 22:10:57 -0700335 INIT_LIST_HEAD(&anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336}
337
338void __init anon_vma_init(void)
339{
340 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
Paul Mundt20c2df82007-07-20 10:11:58 +0900341 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
Rik van Riel5beb4932010-03-05 13:42:07 -0800342 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700343}
344
345/*
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700346 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
347 *
348 * Since there is no serialization what so ever against page_remove_rmap()
349 * the best this function can do is return a locked anon_vma that might
350 * have been relevant to this page.
351 *
352 * The page might have been remapped to a different anon_vma or the anon_vma
353 * returned may already be freed (and even reused).
354 *
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200355 * In case it was remapped to a different anon_vma, the new anon_vma will be a
356 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
357 * ensure that any anon_vma obtained from the page will still be valid for as
358 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
359 *
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700360 * All users of this function must be very careful when walking the anon_vma
361 * chain and verify that the page in question is indeed mapped in it
362 * [ something equivalent to page_mapped_in_vma() ].
363 *
364 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
365 * that the anon_vma pointer from page->mapping is valid if there is a
366 * mapcount, we can dereference the anon_vma after observing those.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700368struct anon_vma *page_get_anon_vma(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369{
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700370 struct anon_vma *anon_vma = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371 unsigned long anon_mapping;
372
373 rcu_read_lock();
Hugh Dickins80e14822009-12-14 17:59:29 -0800374 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800375 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376 goto out;
377 if (!page_mapped(page))
378 goto out;
379
380 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700381 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
382 anon_vma = NULL;
383 goto out;
384 }
Hugh Dickinsf1819422010-08-25 23:12:54 -0700385
386 /*
387 * If this page is still mapped, then its anon_vma cannot have been
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700388 * freed. But if it has been unmapped, we have no security against the
389 * anon_vma structure being freed and reused (for another anon_vma:
390 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
391 * above cannot corrupt).
Hugh Dickinsf1819422010-08-25 23:12:54 -0700392 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700393 if (!page_mapped(page)) {
394 put_anon_vma(anon_vma);
395 anon_vma = NULL;
396 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397out:
398 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700399
400 return anon_vma;
401}
402
Peter Zijlstra88c22082011-05-24 17:12:13 -0700403/*
404 * Similar to page_get_anon_vma() except it locks the anon_vma.
405 *
406 * Its a little more complex as it tries to keep the fast path to a single
407 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
408 * reference like with page_get_anon_vma() and then block on the mutex.
409 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700410struct anon_vma *page_lock_anon_vma(struct page *page)
411{
Peter Zijlstra88c22082011-05-24 17:12:13 -0700412 struct anon_vma *anon_vma = NULL;
Hugh Dickinseee0f252011-05-28 13:20:21 -0700413 struct anon_vma *root_anon_vma;
Peter Zijlstra88c22082011-05-24 17:12:13 -0700414 unsigned long anon_mapping;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700415
Peter Zijlstra88c22082011-05-24 17:12:13 -0700416 rcu_read_lock();
417 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
418 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
419 goto out;
420 if (!page_mapped(page))
421 goto out;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700422
Peter Zijlstra88c22082011-05-24 17:12:13 -0700423 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Hugh Dickinseee0f252011-05-28 13:20:21 -0700424 root_anon_vma = ACCESS_ONCE(anon_vma->root);
425 if (mutex_trylock(&root_anon_vma->mutex)) {
Peter Zijlstra88c22082011-05-24 17:12:13 -0700426 /*
Hugh Dickinseee0f252011-05-28 13:20:21 -0700427 * If the page is still mapped, then this anon_vma is still
428 * its anon_vma, and holding the mutex ensures that it will
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200429 * not go away, see anon_vma_free().
Peter Zijlstra88c22082011-05-24 17:12:13 -0700430 */
Hugh Dickinseee0f252011-05-28 13:20:21 -0700431 if (!page_mapped(page)) {
432 mutex_unlock(&root_anon_vma->mutex);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700433 anon_vma = NULL;
434 }
435 goto out;
436 }
437
438 /* trylock failed, we got to sleep */
439 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
440 anon_vma = NULL;
441 goto out;
442 }
443
444 if (!page_mapped(page)) {
445 put_anon_vma(anon_vma);
446 anon_vma = NULL;
447 goto out;
448 }
449
450 /* we pinned the anon_vma, its safe to sleep */
451 rcu_read_unlock();
452 anon_vma_lock(anon_vma);
453
454 if (atomic_dec_and_test(&anon_vma->refcount)) {
455 /*
456 * Oops, we held the last refcount, release the lock
457 * and bail -- can't simply use put_anon_vma() because
458 * we'll deadlock on the anon_vma_lock() recursion.
459 */
460 anon_vma_unlock(anon_vma);
461 __put_anon_vma(anon_vma);
462 anon_vma = NULL;
463 }
464
465 return anon_vma;
466
467out:
468 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700469 return anon_vma;
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800470}
471
Andi Kleen10be22d2009-09-16 11:50:04 +0200472void page_unlock_anon_vma(struct anon_vma *anon_vma)
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800473{
Rik van Rielcba48b92010-08-09 17:18:38 -0700474 anon_vma_unlock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700475}
476
477/*
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800478 * At what user virtual address is page expected in @vma?
479 * Returns virtual address or -EFAULT if page's index/offset is not
480 * within the range mapped the @vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800482inline unsigned long
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483vma_address(struct page *page, struct vm_area_struct *vma)
484{
485 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
486 unsigned long address;
487
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900488 if (unlikely(is_vm_hugetlb_page(vma)))
489 pgoff = page->index << huge_page_order(page_hstate(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
491 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800492 /* page should be within @vma mapping range */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700493 return -EFAULT;
494 }
495 return address;
496}
497
498/*
Huang Shijiebf89c8c2009-10-01 15:44:04 -0700499 * At what user virtual address is page expected in vma?
Naoya Horiguchiab941e02010-05-11 14:06:55 -0700500 * Caller should check the page is actually part of the vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501 */
502unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
503{
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700504 if (PageAnon(page)) {
Hugh Dickins4829b902010-10-02 17:46:06 -0700505 struct anon_vma *page__anon_vma = page_anon_vma(page);
506 /*
507 * Note: swapoff's unuse_vma() is more efficient with this
508 * check, and needs it to match anon_vma when KSM is active.
509 */
510 if (!vma->anon_vma || !page__anon_vma ||
511 vma->anon_vma->root != page__anon_vma->root)
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700512 return -EFAULT;
513 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800514 if (!vma->vm_file ||
515 vma->vm_file->f_mapping != page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516 return -EFAULT;
517 } else
518 return -EFAULT;
519 return vma_address(page, vma);
520}
521
522/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700523 * Check that @page is mapped at @address into @mm.
524 *
Nick Piggin479db0b2008-08-20 14:09:18 -0700525 * If @sync is false, page_check_address may perform a racy check to avoid
526 * the page table lock when the pte is not present (helpful when reclaiming
527 * highly shared pages).
528 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700529 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700530 */
Namhyung Kime9a81a82010-10-26 14:22:01 -0700531pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
Nick Piggin479db0b2008-08-20 14:09:18 -0700532 unsigned long address, spinlock_t **ptlp, int sync)
Nikita Danilov81b40822005-05-01 08:58:36 -0700533{
534 pgd_t *pgd;
535 pud_t *pud;
536 pmd_t *pmd;
537 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700538 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700539
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900540 if (unlikely(PageHuge(page))) {
541 pte = huge_pte_offset(mm, address);
542 ptl = &mm->page_table_lock;
543 goto check;
544 }
545
Nikita Danilov81b40822005-05-01 08:58:36 -0700546 pgd = pgd_offset(mm, address);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700547 if (!pgd_present(*pgd))
548 return NULL;
549
550 pud = pud_offset(pgd, address);
551 if (!pud_present(*pud))
552 return NULL;
553
554 pmd = pmd_offset(pud, address);
555 if (!pmd_present(*pmd))
556 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800557 if (pmd_trans_huge(*pmd))
558 return NULL;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700559
560 pte = pte_offset_map(pmd, address);
561 /* Make a quick check before getting the lock */
Nick Piggin479db0b2008-08-20 14:09:18 -0700562 if (!sync && !pte_present(*pte)) {
Hugh Dickinsc0718802005-10-29 18:16:31 -0700563 pte_unmap(pte);
564 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700565 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700566
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700567 ptl = pte_lockptr(mm, pmd);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900568check:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700569 spin_lock(ptl);
570 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
571 *ptlp = ptl;
572 return pte;
573 }
574 pte_unmap_unlock(pte, ptl);
575 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700576}
577
Nick Pigginb291f002008-10-18 20:26:44 -0700578/**
579 * page_mapped_in_vma - check whether a page is really mapped in a VMA
580 * @page: the page to test
581 * @vma: the VMA to test
582 *
583 * Returns 1 if the page is mapped into the page tables of the VMA, 0
584 * if the page is not mapped into the page tables of this VMA. Only
585 * valid for normal file or anonymous VMAs.
586 */
Andi Kleen6a460792009-09-16 11:50:15 +0200587int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
Nick Pigginb291f002008-10-18 20:26:44 -0700588{
589 unsigned long address;
590 pte_t *pte;
591 spinlock_t *ptl;
592
593 address = vma_address(page, vma);
594 if (address == -EFAULT) /* out of vma range */
595 return 0;
596 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
597 if (!pte) /* the page is not in this mm */
598 return 0;
599 pte_unmap_unlock(pte, ptl);
600
601 return 1;
602}
603
Nikita Danilov81b40822005-05-01 08:58:36 -0700604/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700605 * Subfunctions of page_referenced: page_referenced_one called
606 * repeatedly from either page_referenced_anon or page_referenced_file.
607 */
Hugh Dickins5ad64682009-12-14 17:59:24 -0800608int page_referenced_one(struct page *page, struct vm_area_struct *vma,
609 unsigned long address, unsigned int *mapcount,
610 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700611{
612 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700613 int referenced = 0;
614
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800615 if (unlikely(PageTransHuge(page))) {
616 pmd_t *pmd;
617
618 spin_lock(&mm->page_table_lock);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800619 /*
620 * rmap might return false positives; we must filter
621 * these out using page_check_address_pmd().
622 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800623 pmd = page_check_address_pmd(page, mm, address,
624 PAGE_CHECK_ADDRESS_PMD_FLAG);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800625 if (!pmd) {
626 spin_unlock(&mm->page_table_lock);
627 goto out;
628 }
629
630 if (vma->vm_flags & VM_LOCKED) {
631 spin_unlock(&mm->page_table_lock);
632 *mapcount = 0; /* break early from loop */
633 *vm_flags |= VM_LOCKED;
634 goto out;
635 }
636
637 /* go ahead even if the pmd is pmd_trans_splitting() */
638 if (pmdp_clear_flush_young_notify(vma, address, pmd))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800639 referenced++;
640 spin_unlock(&mm->page_table_lock);
641 } else {
642 pte_t *pte;
643 spinlock_t *ptl;
644
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800645 /*
646 * rmap might return false positives; we must filter
647 * these out using page_check_address().
648 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800649 pte = page_check_address(page, mm, address, &ptl, 0);
650 if (!pte)
651 goto out;
652
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800653 if (vma->vm_flags & VM_LOCKED) {
654 pte_unmap_unlock(pte, ptl);
655 *mapcount = 0; /* break early from loop */
656 *vm_flags |= VM_LOCKED;
657 goto out;
658 }
659
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800660 if (ptep_clear_flush_young_notify(vma, address, pte)) {
661 /*
662 * Don't treat a reference through a sequentially read
663 * mapping as such. If the page has been used in
664 * another mapping, we will catch it; if this other
665 * mapping is already gone, the unmap path will have
666 * set PG_referenced or activated the page.
667 */
668 if (likely(!VM_SequentialReadHint(vma)))
669 referenced++;
670 }
671 pte_unmap_unlock(pte, ptl);
672 }
673
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800674 /* Pretend the page is referenced if the task has the
675 swap token and is in the middle of a page fault. */
676 if (mm != current->mm && has_swap_token(mm) &&
677 rwsem_is_locked(&mm->mmap_sem))
678 referenced++;
679
Hugh Dickinsc0718802005-10-29 18:16:31 -0700680 (*mapcount)--;
Huang Shijie273f0472009-12-14 17:58:51 -0800681
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700682 if (referenced)
683 *vm_flags |= vma->vm_flags;
Huang Shijie273f0472009-12-14 17:58:51 -0800684out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700685 return referenced;
686}
687
Balbir Singhbed71612008-02-07 00:14:01 -0800688static int page_referenced_anon(struct page *page,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700689 struct mem_cgroup *mem_cont,
690 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700691{
692 unsigned int mapcount;
693 struct anon_vma *anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800694 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695 int referenced = 0;
696
697 anon_vma = page_lock_anon_vma(page);
698 if (!anon_vma)
699 return referenced;
700
701 mapcount = page_mapcount(page);
Rik van Riel5beb4932010-03-05 13:42:07 -0800702 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
703 struct vm_area_struct *vma = avc->vma;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800704 unsigned long address = vma_address(page, vma);
705 if (address == -EFAULT)
706 continue;
Balbir Singhbed71612008-02-07 00:14:01 -0800707 /*
708 * If we are reclaiming on behalf of a cgroup, skip
709 * counting on behalf of references from different
710 * cgroups
711 */
Hugh Dickinsbd845e32008-03-04 14:29:01 -0800712 if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
Balbir Singhbed71612008-02-07 00:14:01 -0800713 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800714 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700715 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700716 if (!mapcount)
717 break;
718 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800719
720 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700721 return referenced;
722}
723
724/**
725 * page_referenced_file - referenced check for object-based rmap
726 * @page: the page we're checking references on.
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700727 * @mem_cont: target memory controller
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700728 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700729 *
730 * For an object-based mapped page, find all the places it is mapped and
731 * check/clear the referenced flag. This is done by following the page->mapping
732 * pointer, then walking the chain of vmas it holds. It returns the number
733 * of references it found.
734 *
735 * This function is only called from page_referenced for object-based pages.
736 */
Balbir Singhbed71612008-02-07 00:14:01 -0800737static int page_referenced_file(struct page *page,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700738 struct mem_cgroup *mem_cont,
739 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740{
741 unsigned int mapcount;
742 struct address_space *mapping = page->mapping;
743 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
744 struct vm_area_struct *vma;
745 struct prio_tree_iter iter;
746 int referenced = 0;
747
748 /*
749 * The caller's checks on page->mapping and !PageAnon have made
750 * sure that this is a file page: the check for page->mapping
751 * excludes the case just before it gets set on an anon page.
752 */
753 BUG_ON(PageAnon(page));
754
755 /*
756 * The page lock not only makes sure that page->mapping cannot
757 * suddenly be NULLified by truncation, it makes sure that the
758 * structure at mapping cannot be freed and reused yet,
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700759 * so we can safely take mapping->i_mmap_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700760 */
761 BUG_ON(!PageLocked(page));
762
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700763 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700764
765 /*
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700766 * i_mmap_mutex does not stabilize mapcount at all, but mapcount
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 * is more likely to be accurate if we note it after spinning.
768 */
769 mapcount = page_mapcount(page);
770
771 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800772 unsigned long address = vma_address(page, vma);
773 if (address == -EFAULT)
774 continue;
Balbir Singhbed71612008-02-07 00:14:01 -0800775 /*
776 * If we are reclaiming on behalf of a cgroup, skip
777 * counting on behalf of references from different
778 * cgroups
779 */
Hugh Dickinsbd845e32008-03-04 14:29:01 -0800780 if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont))
Balbir Singhbed71612008-02-07 00:14:01 -0800781 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800782 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700783 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700784 if (!mapcount)
785 break;
786 }
787
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700788 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789 return referenced;
790}
791
792/**
793 * page_referenced - test if the page was referenced
794 * @page: the page to test
795 * @is_locked: caller holds lock on the page
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700796 * @mem_cont: target memory controller
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700797 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700798 *
799 * Quick test_and_clear_referenced for all mappings to a page,
800 * returns the number of ptes which referenced the page.
801 */
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700802int page_referenced(struct page *page,
803 int is_locked,
804 struct mem_cgroup *mem_cont,
805 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700806{
807 int referenced = 0;
Hugh Dickins5ad64682009-12-14 17:59:24 -0800808 int we_locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700809
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700810 *vm_flags = 0;
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800811 if (page_mapped(page) && page_rmapping(page)) {
Hugh Dickins5ad64682009-12-14 17:59:24 -0800812 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
813 we_locked = trylock_page(page);
814 if (!we_locked) {
815 referenced++;
816 goto out;
817 }
818 }
819 if (unlikely(PageKsm(page)))
820 referenced += page_referenced_ksm(page, mem_cont,
821 vm_flags);
822 else if (PageAnon(page))
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700823 referenced += page_referenced_anon(page, mem_cont,
824 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800825 else if (page->mapping)
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700826 referenced += page_referenced_file(page, mem_cont,
827 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800828 if (we_locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700829 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 }
Hugh Dickins5ad64682009-12-14 17:59:24 -0800831out:
Martin Schwidefsky2d425522011-05-23 10:24:39 +0200832 if (page_test_and_clear_young(page_to_pfn(page)))
Christian Borntraeger5b7baf02008-03-25 18:47:12 +0100833 referenced++;
834
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 return referenced;
836}
837
Hugh Dickins1cb17292009-12-14 17:59:01 -0800838static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
839 unsigned long address)
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700840{
841 struct mm_struct *mm = vma->vm_mm;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100842 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700843 spinlock_t *ptl;
844 int ret = 0;
845
Nick Piggin479db0b2008-08-20 14:09:18 -0700846 pte = page_check_address(page, mm, address, &ptl, 1);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700847 if (!pte)
848 goto out;
849
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100850 if (pte_dirty(*pte) || pte_write(*pte)) {
851 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700852
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100853 flush_cache_page(vma, address, pte_pfn(*pte));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700854 entry = ptep_clear_flush_notify(vma, address, pte);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100855 entry = pte_wrprotect(entry);
856 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -0800857 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100858 ret = 1;
859 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700860
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700861 pte_unmap_unlock(pte, ptl);
862out:
863 return ret;
864}
865
866static int page_mkclean_file(struct address_space *mapping, struct page *page)
867{
868 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
869 struct vm_area_struct *vma;
870 struct prio_tree_iter iter;
871 int ret = 0;
872
873 BUG_ON(PageAnon(page));
874
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700875 mutex_lock(&mapping->i_mmap_mutex);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700876 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800877 if (vma->vm_flags & VM_SHARED) {
878 unsigned long address = vma_address(page, vma);
879 if (address == -EFAULT)
880 continue;
881 ret += page_mkclean_one(page, vma, address);
882 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700883 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700884 mutex_unlock(&mapping->i_mmap_mutex);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700885 return ret;
886}
887
888int page_mkclean(struct page *page)
889{
890 int ret = 0;
891
892 BUG_ON(!PageLocked(page));
893
894 if (page_mapped(page)) {
895 struct address_space *mapping = page_mapping(page);
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100896 if (mapping) {
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700897 ret = page_mkclean_file(mapping, page);
Martin Schwidefsky2d425522011-05-23 10:24:39 +0200898 if (page_test_and_clear_dirty(page_to_pfn(page), 1))
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100899 ret = 1;
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200900 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700901 }
902
903 return ret;
904}
Jaya Kumar60b59be2007-05-08 00:37:37 -0700905EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700906
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907/**
Rik van Rielc44b6742010-03-05 13:42:09 -0800908 * page_move_anon_rmap - move a page to our anon_vma
909 * @page: the page to move to our anon_vma
910 * @vma: the vma the page belongs to
911 * @address: the user virtual address mapped
912 *
913 * When a page belongs exclusively to one process after a COW event,
914 * that page can be moved into the anon_vma that belongs to just that
915 * process, so the rmap code will not search the parent or sibling
916 * processes.
917 */
918void page_move_anon_rmap(struct page *page,
919 struct vm_area_struct *vma, unsigned long address)
920{
921 struct anon_vma *anon_vma = vma->anon_vma;
922
923 VM_BUG_ON(!PageLocked(page));
924 VM_BUG_ON(!anon_vma);
925 VM_BUG_ON(page->index != linear_page_index(vma, address));
926
927 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
928 page->mapping = (struct address_space *) anon_vma;
929}
930
931/**
Andi Kleen4e1c1972010-09-22 12:43:56 +0200932 * __page_set_anon_rmap - set up new anonymous rmap
933 * @page: Page to add to rmap
934 * @vma: VM area to add page to.
935 * @address: User virtual address of the mapping
Rik van Riele8a03fe2010-04-14 17:59:28 -0400936 * @exclusive: the page is exclusively owned by the current process
Nick Piggin9617d952006-01-06 00:11:12 -0800937 */
938static void __page_set_anon_rmap(struct page *page,
Rik van Riele8a03fe2010-04-14 17:59:28 -0400939 struct vm_area_struct *vma, unsigned long address, int exclusive)
Nick Piggin9617d952006-01-06 00:11:12 -0800940{
Rik van Riele8a03fe2010-04-14 17:59:28 -0400941 struct anon_vma *anon_vma = vma->anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -0800942
Rik van Riele8a03fe2010-04-14 17:59:28 -0400943 BUG_ON(!anon_vma);
Linus Torvaldsea900022010-04-12 12:44:29 -0700944
Andi Kleen4e1c1972010-09-22 12:43:56 +0200945 if (PageAnon(page))
946 return;
947
Linus Torvaldsea900022010-04-12 12:44:29 -0700948 /*
Rik van Riele8a03fe2010-04-14 17:59:28 -0400949 * If the page isn't exclusively mapped into this vma,
950 * we must use the _oldest_ possible anon_vma for the
951 * page mapping!
Linus Torvaldsea900022010-04-12 12:44:29 -0700952 */
Andi Kleen4e1c1972010-09-22 12:43:56 +0200953 if (!exclusive)
Andrea Arcangeli288468c2010-08-09 17:19:09 -0700954 anon_vma = anon_vma->root;
Linus Torvaldsea900022010-04-12 12:44:29 -0700955
Nick Piggin9617d952006-01-06 00:11:12 -0800956 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
957 page->mapping = (struct address_space *) anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -0800958 page->index = linear_page_index(vma, address);
Nick Piggin9617d952006-01-06 00:11:12 -0800959}
960
961/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700962 * __page_check_anon_rmap - sanity check anonymous rmap addition
Nick Pigginc97a9e12007-05-16 22:11:21 -0700963 * @page: the page to add the mapping to
964 * @vma: the vm area in which the mapping is added
965 * @address: the user virtual address mapped
966 */
967static void __page_check_anon_rmap(struct page *page,
968 struct vm_area_struct *vma, unsigned long address)
969{
970#ifdef CONFIG_DEBUG_VM
971 /*
972 * The page's anon-rmap details (mapping and index) are guaranteed to
973 * be set up correctly at this point.
974 *
975 * We have exclusion against page_add_anon_rmap because the caller
976 * always holds the page locked, except if called from page_dup_rmap,
977 * in which case the page is already known to be setup.
978 *
979 * We have exclusion against page_add_new_anon_rmap because those pages
980 * are initially only visible via the pagetables, and the pte is locked
981 * over the call to page_add_new_anon_rmap.
982 */
Andrea Arcangeli44ab57a2010-08-09 17:19:10 -0700983 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
Nick Pigginc97a9e12007-05-16 22:11:21 -0700984 BUG_ON(page->index != linear_page_index(vma, address));
985#endif
986}
987
988/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700989 * page_add_anon_rmap - add pte mapping to an anonymous page
990 * @page: the page to add the mapping to
991 * @vma: the vm area in which the mapping is added
992 * @address: the user virtual address mapped
993 *
Hugh Dickins5ad64682009-12-14 17:59:24 -0800994 * The caller needs to hold the pte lock, and the page must be locked in
Hugh Dickins80e14822009-12-14 17:59:29 -0800995 * the anon_vma case: to serialize mapping,index checking after setting,
996 * and to ensure that PageAnon is not being upgraded racily to PageKsm
997 * (but PageKsm is never downgraded to PageAnon).
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 */
999void page_add_anon_rmap(struct page *page,
1000 struct vm_area_struct *vma, unsigned long address)
1001{
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001002 do_page_add_anon_rmap(page, vma, address, 0);
1003}
1004
1005/*
1006 * Special version of the above for do_swap_page, which often runs
1007 * into pages that are exclusively owned by the current process.
1008 * Everybody else should continue to use page_add_anon_rmap above.
1009 */
1010void do_page_add_anon_rmap(struct page *page,
1011 struct vm_area_struct *vma, unsigned long address, int exclusive)
1012{
Hugh Dickins5ad64682009-12-14 17:59:24 -08001013 int first = atomic_inc_and_test(&page->_mapcount);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001014 if (first) {
1015 if (!PageTransHuge(page))
1016 __inc_zone_page_state(page, NR_ANON_PAGES);
1017 else
1018 __inc_zone_page_state(page,
1019 NR_ANON_TRANSPARENT_HUGEPAGES);
1020 }
Hugh Dickins5ad64682009-12-14 17:59:24 -08001021 if (unlikely(PageKsm(page)))
1022 return;
1023
Nick Pigginc97a9e12007-05-16 22:11:21 -07001024 VM_BUG_ON(!PageLocked(page));
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001025 /* address might be in next vma when migration races vma_adjust */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001026 if (first)
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001027 __page_set_anon_rmap(page, vma, address, exclusive);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001028 else
Nick Pigginc97a9e12007-05-16 22:11:21 -07001029 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001030}
1031
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001032/**
Nick Piggin9617d952006-01-06 00:11:12 -08001033 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1034 * @page: the page to add the mapping to
1035 * @vma: the vm area in which the mapping is added
1036 * @address: the user virtual address mapped
1037 *
1038 * Same as page_add_anon_rmap but must only be called on *new* pages.
1039 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -07001040 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -08001041 */
1042void page_add_new_anon_rmap(struct page *page,
1043 struct vm_area_struct *vma, unsigned long address)
1044{
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001045 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001046 SetPageSwapBacked(page);
1047 atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
Andrea Arcangeli79134172011-01-13 15:46:58 -08001048 if (!PageTransHuge(page))
1049 __inc_zone_page_state(page, NR_ANON_PAGES);
1050 else
1051 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
Rik van Riele8a03fe2010-04-14 17:59:28 -04001052 __page_set_anon_rmap(page, vma, address, 1);
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001053 if (page_evictable(page, vma))
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001054 lru_cache_add_lru(page, LRU_ACTIVE_ANON);
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001055 else
1056 add_page_to_unevictable_list(page);
Nick Piggin9617d952006-01-06 00:11:12 -08001057}
1058
Linus Torvalds1da177e2005-04-16 15:20:36 -07001059/**
1060 * page_add_file_rmap - add pte mapping to a file page
1061 * @page: the page to add the mapping to
1062 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001063 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001064 */
1065void page_add_file_rmap(struct page *page)
1066{
Balbir Singhd69b0422009-06-17 16:26:34 -07001067 if (atomic_inc_and_test(&page->_mapcount)) {
Christoph Lameter65ba55f2006-06-30 01:55:34 -07001068 __inc_zone_page_state(page, NR_FILE_MAPPED);
Greg Thelen2a7106f2011-01-13 15:47:37 -08001069 mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED);
Balbir Singhd69b0422009-06-17 16:26:34 -07001070 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001071}
1072
1073/**
1074 * page_remove_rmap - take down pte mapping from a page
1075 * @page: page to remove mapping from
1076 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001077 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001078 */
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001079void page_remove_rmap(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001080{
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001081 /* page still mapped by someone else? */
1082 if (!atomic_add_negative(-1, &page->_mapcount))
1083 return;
1084
1085 /*
1086 * Now that the last pte has gone, s390 must transfer dirty
1087 * flag from storage key to struct page. We can usually skip
1088 * this if the page is anon, so about to be freed; but perhaps
1089 * not if it's in swapcache - there might be another pte slot
1090 * containing the swap entry, but page not yet written to swap.
1091 */
Martin Schwidefsky2d425522011-05-23 10:24:39 +02001092 if ((!PageAnon(page) || PageSwapCache(page)) &&
1093 page_test_and_clear_dirty(page_to_pfn(page), 1))
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001094 set_page_dirty(page);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001095 /*
1096 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
1097 * and not charged by memcg for now.
1098 */
1099 if (unlikely(PageHuge(page)))
1100 return;
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001101 if (PageAnon(page)) {
1102 mem_cgroup_uncharge_page(page);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001103 if (!PageTransHuge(page))
1104 __dec_zone_page_state(page, NR_ANON_PAGES);
1105 else
1106 __dec_zone_page_state(page,
1107 NR_ANON_TRANSPARENT_HUGEPAGES);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001108 } else {
1109 __dec_zone_page_state(page, NR_FILE_MAPPED);
Greg Thelen2a7106f2011-01-13 15:47:37 -08001110 mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001111 }
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001112 /*
1113 * It would be tidy to reset the PageAnon mapping here,
1114 * but that might overwrite a racing page_add_anon_rmap
1115 * which increments mapcount after us but sets mapping
1116 * before us: so leave the reset to free_hot_cold_page,
1117 * and remember that it's only reliable while mapped.
1118 * Leaving it set also helps swapoff to reinstate ptes
1119 * faster for those pages still in swapcache.
1120 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001121}
1122
1123/*
1124 * Subfunctions of try_to_unmap: try_to_unmap_one called
1125 * repeatedly from either try_to_unmap_anon or try_to_unmap_file.
1126 */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001127int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1128 unsigned long address, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001129{
1130 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001131 pte_t *pte;
1132 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001133 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001134 int ret = SWAP_AGAIN;
1135
Nick Piggin479db0b2008-08-20 14:09:18 -07001136 pte = page_check_address(page, mm, address, &ptl, 0);
Hugh Dickinsc0718802005-10-29 18:16:31 -07001137 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -07001138 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001139
1140 /*
1141 * If the page is mlock()d, we cannot swap it out.
1142 * If it's recently referenced (perhaps page_referenced
1143 * skipped over this mm) then we should reactivate it.
1144 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001145 if (!(flags & TTU_IGNORE_MLOCK)) {
KOSAKI Motohirocaed0f42009-12-14 17:59:45 -08001146 if (vma->vm_flags & VM_LOCKED)
1147 goto out_mlock;
1148
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001149 if (TTU_ACTION(flags) == TTU_MUNLOCK)
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001150 goto out_unmap;
Andi Kleen14fa31b2009-09-16 11:50:10 +02001151 }
1152 if (!(flags & TTU_IGNORE_ACCESS)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001153 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1154 ret = SWAP_FAIL;
1155 goto out_unmap;
1156 }
1157 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001158
Linus Torvalds1da177e2005-04-16 15:20:36 -07001159 /* Nuke the page table entry. */
1160 flush_cache_page(vma, address, page_to_pfn(page));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001161 pteval = ptep_clear_flush_notify(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001162
1163 /* Move the dirty bit to the physical page now the pte is gone. */
1164 if (pte_dirty(pteval))
1165 set_page_dirty(page);
1166
Hugh Dickins365e9c872005-10-29 18:16:18 -07001167 /* Update high watermark before we lower rss */
1168 update_hiwater_rss(mm);
1169
Andi Kleen888b9f72009-09-16 11:50:11 +02001170 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
1171 if (PageAnon(page))
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001172 dec_mm_counter(mm, MM_ANONPAGES);
Andi Kleen888b9f72009-09-16 11:50:11 +02001173 else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001174 dec_mm_counter(mm, MM_FILEPAGES);
Andi Kleen888b9f72009-09-16 11:50:11 +02001175 set_pte_at(mm, address, pte,
1176 swp_entry_to_pte(make_hwpoison_entry(page)));
1177 } else if (PageAnon(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001178 swp_entry_t entry = { .val = page_private(page) };
Christoph Lameter06972122006-06-23 02:03:35 -07001179
1180 if (PageSwapCache(page)) {
1181 /*
1182 * Store the swap location in the pte.
1183 * See handle_pte_fault() ...
1184 */
Hugh Dickins570a3352009-12-14 17:58:46 -08001185 if (swap_duplicate(entry) < 0) {
1186 set_pte_at(mm, address, pte, pteval);
1187 ret = SWAP_FAIL;
1188 goto out_unmap;
1189 }
Christoph Lameter06972122006-06-23 02:03:35 -07001190 if (list_empty(&mm->mmlist)) {
1191 spin_lock(&mmlist_lock);
1192 if (list_empty(&mm->mmlist))
1193 list_add(&mm->mmlist, &init_mm.mmlist);
1194 spin_unlock(&mmlist_lock);
1195 }
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001196 dec_mm_counter(mm, MM_ANONPAGES);
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -08001197 inc_mm_counter(mm, MM_SWAPENTS);
KOSAKI Motohiro64cdd542009-01-06 14:39:16 -08001198 } else if (PAGE_MIGRATION) {
Christoph Lameter06972122006-06-23 02:03:35 -07001199 /*
1200 * Store the pfn of the page in a special migration
1201 * pte. do_swap_page() will wait until the migration
1202 * pte is removed and then restart fault handling.
1203 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001204 BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION);
Christoph Lameter06972122006-06-23 02:03:35 -07001205 entry = make_migration_entry(page, pte_write(pteval));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206 }
1207 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1208 BUG_ON(pte_file(*pte));
Andi Kleen14fa31b2009-09-16 11:50:10 +02001209 } else if (PAGE_MIGRATION && (TTU_ACTION(flags) == TTU_MIGRATION)) {
Christoph Lameter04e62a22006-06-23 02:03:38 -07001210 /* Establish migration entry for a file page */
1211 swp_entry_t entry;
1212 entry = make_migration_entry(page, pte_write(pteval));
1213 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1214 } else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001215 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001216
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001217 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001218 page_cache_release(page);
1219
1220out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -07001221 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001222out:
1223 return ret;
KOSAKI Motohirocaed0f42009-12-14 17:59:45 -08001224
1225out_mlock:
1226 pte_unmap_unlock(pte, ptl);
1227
1228
1229 /*
1230 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
1231 * unstable result and race. Plus, We can't wait here because
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001232 * we now hold anon_vma->mutex or mapping->i_mmap_mutex.
KOSAKI Motohirocaed0f42009-12-14 17:59:45 -08001233 * if trylock failed, the page remain in evictable lru and later
1234 * vmscan could retry to move the page to unevictable lru if the
1235 * page is actually mlocked.
1236 */
1237 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
1238 if (vma->vm_flags & VM_LOCKED) {
1239 mlock_vma_page(page);
1240 ret = SWAP_MLOCK;
1241 }
1242 up_read(&vma->vm_mm->mmap_sem);
1243 }
1244 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001245}
1246
1247/*
1248 * objrmap doesn't work for nonlinear VMAs because the assumption that
1249 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
1250 * Consequently, given a particular page and its ->index, we cannot locate the
1251 * ptes which are mapping that page without an exhaustive linear search.
1252 *
1253 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
1254 * maps the file to which the target page belongs. The ->vm_private_data field
1255 * holds the current cursor into that scan. Successive searches will circulate
1256 * around the vma's virtual address space.
1257 *
1258 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
1259 * more scanning pressure is placed against them as well. Eventually pages
1260 * will become fully unmapped and are eligible for eviction.
1261 *
1262 * For very sparsely populated VMAs this is a little inefficient - chances are
1263 * there there won't be many ptes located within the scan cluster. In this case
1264 * maybe we could scan further - to the end of the pte page, perhaps.
Nick Pigginb291f002008-10-18 20:26:44 -07001265 *
1266 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
1267 * acquire it without blocking. If vma locked, mlock the pages in the cluster,
1268 * rather than unmapping them. If we encounter the "check_page" that vmscan is
1269 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001270 */
1271#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
1272#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
1273
Nick Pigginb291f002008-10-18 20:26:44 -07001274static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
1275 struct vm_area_struct *vma, struct page *check_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001276{
1277 struct mm_struct *mm = vma->vm_mm;
1278 pgd_t *pgd;
1279 pud_t *pud;
1280 pmd_t *pmd;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001281 pte_t *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001283 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284 struct page *page;
1285 unsigned long address;
1286 unsigned long end;
Nick Pigginb291f002008-10-18 20:26:44 -07001287 int ret = SWAP_AGAIN;
1288 int locked_vma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001289
Linus Torvalds1da177e2005-04-16 15:20:36 -07001290 address = (vma->vm_start + cursor) & CLUSTER_MASK;
1291 end = address + CLUSTER_SIZE;
1292 if (address < vma->vm_start)
1293 address = vma->vm_start;
1294 if (end > vma->vm_end)
1295 end = vma->vm_end;
1296
1297 pgd = pgd_offset(mm, address);
1298 if (!pgd_present(*pgd))
Nick Pigginb291f002008-10-18 20:26:44 -07001299 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001300
1301 pud = pud_offset(pgd, address);
1302 if (!pud_present(*pud))
Nick Pigginb291f002008-10-18 20:26:44 -07001303 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304
1305 pmd = pmd_offset(pud, address);
1306 if (!pmd_present(*pmd))
Nick Pigginb291f002008-10-18 20:26:44 -07001307 return ret;
1308
1309 /*
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001310 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
Nick Pigginb291f002008-10-18 20:26:44 -07001311 * keep the sem while scanning the cluster for mlocking pages.
1312 */
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001313 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001314 locked_vma = (vma->vm_flags & VM_LOCKED);
1315 if (!locked_vma)
1316 up_read(&vma->vm_mm->mmap_sem); /* don't need it */
1317 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001318
1319 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001320
Hugh Dickins365e9c872005-10-29 18:16:18 -07001321 /* Update high watermark before we lower rss */
1322 update_hiwater_rss(mm);
1323
Hugh Dickinsc0718802005-10-29 18:16:31 -07001324 for (; address < end; pte++, address += PAGE_SIZE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001325 if (!pte_present(*pte))
1326 continue;
Linus Torvalds6aab3412005-11-28 14:34:23 -08001327 page = vm_normal_page(vma, address, *pte);
1328 BUG_ON(!page || PageAnon(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001329
Nick Pigginb291f002008-10-18 20:26:44 -07001330 if (locked_vma) {
1331 mlock_vma_page(page); /* no-op if already mlocked */
1332 if (page == check_page)
1333 ret = SWAP_MLOCK;
1334 continue; /* don't unmap */
1335 }
1336
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001337 if (ptep_clear_flush_young_notify(vma, address, pte))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001338 continue;
1339
1340 /* Nuke the page table entry. */
Ben Collinseca35132005-11-29 11:45:26 -08001341 flush_cache_page(vma, address, pte_pfn(*pte));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001342 pteval = ptep_clear_flush_notify(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001343
1344 /* If nonlinear, store the file page offset in the pte. */
1345 if (page->index != linear_page_index(vma, address))
1346 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
1347
1348 /* Move the dirty bit to the physical page now the pte is gone. */
1349 if (pte_dirty(pteval))
1350 set_page_dirty(page);
1351
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001352 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353 page_cache_release(page);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001354 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001355 (*mapcount)--;
1356 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001357 pte_unmap_unlock(pte - 1, ptl);
Nick Pigginb291f002008-10-18 20:26:44 -07001358 if (locked_vma)
1359 up_read(&vma->vm_mm->mmap_sem);
1360 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361}
1362
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001363bool is_vma_temporary_stack(struct vm_area_struct *vma)
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001364{
1365 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1366
1367 if (!maybe_stack)
1368 return false;
1369
1370 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1371 VM_STACK_INCOMPLETE_SETUP)
1372 return true;
1373
1374 return false;
1375}
1376
Nick Pigginb291f002008-10-18 20:26:44 -07001377/**
1378 * try_to_unmap_anon - unmap or unlock anonymous page using the object-based
1379 * rmap method
1380 * @page: the page to unmap/unlock
Huang Shijie8051be52009-12-14 17:58:50 -08001381 * @flags: action and flags
Nick Pigginb291f002008-10-18 20:26:44 -07001382 *
1383 * Find all the mappings of a page using the mapping pointer and the vma chains
1384 * contained in the anon_vma struct it points to.
1385 *
1386 * This function is only called from try_to_unmap/try_to_munlock for
1387 * anonymous pages.
1388 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1389 * where the page was found will be held for write. So, we won't recheck
1390 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1391 * 'LOCKED.
1392 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001393static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001394{
1395 struct anon_vma *anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08001396 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001397 int ret = SWAP_AGAIN;
Nick Pigginb291f002008-10-18 20:26:44 -07001398
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399 anon_vma = page_lock_anon_vma(page);
1400 if (!anon_vma)
1401 return ret;
1402
Rik van Riel5beb4932010-03-05 13:42:07 -08001403 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1404 struct vm_area_struct *vma = avc->vma;
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001405 unsigned long address;
1406
1407 /*
1408 * During exec, a temporary VMA is setup and later moved.
1409 * The VMA is moved under the anon_vma lock but not the
1410 * page tables leading to a race where migration cannot
1411 * find the migration ptes. Rather than increasing the
1412 * locking requirements of exec(), migration skips
1413 * temporary VMAs until after exec() completes.
1414 */
1415 if (PAGE_MIGRATION && (flags & TTU_MIGRATION) &&
1416 is_vma_temporary_stack(vma))
1417 continue;
1418
1419 address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -08001420 if (address == -EFAULT)
1421 continue;
1422 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001423 if (ret != SWAP_AGAIN || !page_mapped(page))
1424 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001425 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -08001426
1427 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428 return ret;
1429}
1430
1431/**
Nick Pigginb291f002008-10-18 20:26:44 -07001432 * try_to_unmap_file - unmap/unlock file page using the object-based rmap method
1433 * @page: the page to unmap/unlock
Andi Kleen14fa31b2009-09-16 11:50:10 +02001434 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001435 *
1436 * Find all the mappings of a page using the mapping pointer and the vma chains
1437 * contained in the address_space struct it points to.
1438 *
Nick Pigginb291f002008-10-18 20:26:44 -07001439 * This function is only called from try_to_unmap/try_to_munlock for
1440 * object-based pages.
1441 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1442 * where the page was found will be held for write. So, we won't recheck
1443 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1444 * 'LOCKED.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001445 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001446static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001447{
1448 struct address_space *mapping = page->mapping;
1449 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1450 struct vm_area_struct *vma;
1451 struct prio_tree_iter iter;
1452 int ret = SWAP_AGAIN;
1453 unsigned long cursor;
1454 unsigned long max_nl_cursor = 0;
1455 unsigned long max_nl_size = 0;
1456 unsigned int mapcount;
1457
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001458 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -08001460 unsigned long address = vma_address(page, vma);
1461 if (address == -EFAULT)
1462 continue;
1463 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001464 if (ret != SWAP_AGAIN || !page_mapped(page))
1465 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 }
1467
1468 if (list_empty(&mapping->i_mmap_nonlinear))
1469 goto out;
1470
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001471 /*
1472 * We don't bother to try to find the munlocked page in nonlinears.
1473 * It's costly. Instead, later, page reclaim logic may call
1474 * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily.
1475 */
1476 if (TTU_ACTION(flags) == TTU_MUNLOCK)
1477 goto out;
1478
Linus Torvalds1da177e2005-04-16 15:20:36 -07001479 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
1480 shared.vm_set.list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001481 cursor = (unsigned long) vma->vm_private_data;
1482 if (cursor > max_nl_cursor)
1483 max_nl_cursor = cursor;
1484 cursor = vma->vm_end - vma->vm_start;
1485 if (cursor > max_nl_size)
1486 max_nl_size = cursor;
1487 }
1488
Nick Pigginb291f002008-10-18 20:26:44 -07001489 if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 ret = SWAP_FAIL;
1491 goto out;
1492 }
1493
1494 /*
1495 * We don't try to search for this page in the nonlinear vmas,
1496 * and page_referenced wouldn't have found it anyway. Instead
1497 * just walk the nonlinear vmas trying to age and unmap some.
1498 * The mapcount of the page we came in with is irrelevant,
1499 * but even so use it as a guide to how hard we should try?
1500 */
1501 mapcount = page_mapcount(page);
1502 if (!mapcount)
1503 goto out;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001504 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505
1506 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
1507 if (max_nl_cursor == 0)
1508 max_nl_cursor = CLUSTER_SIZE;
1509
1510 do {
1511 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
1512 shared.vm_set.list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001513 cursor = (unsigned long) vma->vm_private_data;
Hugh Dickins839b9682005-09-03 15:54:43 -07001514 while ( cursor < max_nl_cursor &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001515 cursor < vma->vm_end - vma->vm_start) {
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001516 if (try_to_unmap_cluster(cursor, &mapcount,
1517 vma, page) == SWAP_MLOCK)
1518 ret = SWAP_MLOCK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001519 cursor += CLUSTER_SIZE;
1520 vma->vm_private_data = (void *) cursor;
1521 if ((int)mapcount <= 0)
1522 goto out;
1523 }
1524 vma->vm_private_data = (void *) max_nl_cursor;
1525 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001526 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 max_nl_cursor += CLUSTER_SIZE;
1528 } while (max_nl_cursor <= max_nl_size);
1529
1530 /*
1531 * Don't loop forever (perhaps all the remaining pages are
1532 * in locked vmas). Reset cursor on all unreserved nonlinear
1533 * vmas, now forgetting on which ones it had fallen behind.
1534 */
Hugh Dickins101d2be2005-11-21 21:32:16 -08001535 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1536 vma->vm_private_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001537out:
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001538 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001539 return ret;
1540}
1541
1542/**
1543 * try_to_unmap - try to remove all page table mappings to a page
1544 * @page: the page to get unmapped
Andi Kleen14fa31b2009-09-16 11:50:10 +02001545 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 *
1547 * Tries to remove all the page table entries which are mapping this
1548 * page, used in the pageout path. Caller must hold the page lock.
1549 * Return values are:
1550 *
1551 * SWAP_SUCCESS - we succeeded in removing all mappings
1552 * SWAP_AGAIN - we missed a mapping, try again later
1553 * SWAP_FAIL - the page is unswappable
Nick Pigginb291f002008-10-18 20:26:44 -07001554 * SWAP_MLOCK - page is mlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001556int try_to_unmap(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001557{
1558 int ret;
1559
Linus Torvalds1da177e2005-04-16 15:20:36 -07001560 BUG_ON(!PageLocked(page));
Andrea Arcangeli91600e92011-01-13 15:47:16 -08001561 VM_BUG_ON(!PageHuge(page) && PageTransHuge(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001562
Hugh Dickins5ad64682009-12-14 17:59:24 -08001563 if (unlikely(PageKsm(page)))
1564 ret = try_to_unmap_ksm(page, flags);
1565 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001566 ret = try_to_unmap_anon(page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001567 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001568 ret = try_to_unmap_file(page, flags);
Nick Pigginb291f002008-10-18 20:26:44 -07001569 if (ret != SWAP_MLOCK && !page_mapped(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570 ret = SWAP_SUCCESS;
1571 return ret;
1572}
Nikita Danilov81b40822005-05-01 08:58:36 -07001573
Nick Pigginb291f002008-10-18 20:26:44 -07001574/**
1575 * try_to_munlock - try to munlock a page
1576 * @page: the page to be munlocked
1577 *
1578 * Called from munlock code. Checks all of the VMAs mapping the page
1579 * to make sure nobody else has this page mlocked. The page will be
1580 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1581 *
1582 * Return values are:
1583 *
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001584 * SWAP_AGAIN - no vma is holding page mlocked, or,
Nick Pigginb291f002008-10-18 20:26:44 -07001585 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
Hugh Dickins5ad64682009-12-14 17:59:24 -08001586 * SWAP_FAIL - page cannot be located at present
Nick Pigginb291f002008-10-18 20:26:44 -07001587 * SWAP_MLOCK - page is now mlocked.
1588 */
1589int try_to_munlock(struct page *page)
1590{
1591 VM_BUG_ON(!PageLocked(page) || PageLRU(page));
1592
Hugh Dickins5ad64682009-12-14 17:59:24 -08001593 if (unlikely(PageKsm(page)))
1594 return try_to_unmap_ksm(page, TTU_MUNLOCK);
1595 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001596 return try_to_unmap_anon(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001597 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001598 return try_to_unmap_file(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001599}
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001600
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001601void __put_anon_vma(struct anon_vma *anon_vma)
Rik van Riel76545062010-08-09 17:18:41 -07001602{
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001603 struct anon_vma *root = anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -07001604
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001605 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1606 anon_vma_free(root);
Rik van Riel76545062010-08-09 17:18:41 -07001607
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001608 anon_vma_free(anon_vma);
Rik van Riel76545062010-08-09 17:18:41 -07001609}
Rik van Riel76545062010-08-09 17:18:41 -07001610
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001611#ifdef CONFIG_MIGRATION
1612/*
1613 * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
1614 * Called by migrate.c to remove migration ptes, but might be used more later.
1615 */
1616static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
1617 struct vm_area_struct *, unsigned long, void *), void *arg)
1618{
1619 struct anon_vma *anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08001620 struct anon_vma_chain *avc;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001621 int ret = SWAP_AGAIN;
1622
1623 /*
1624 * Note: remove_migration_ptes() cannot use page_lock_anon_vma()
1625 * because that depends on page_mapped(); but not all its usages
Mel Gorman3f6c8272010-05-24 14:32:17 -07001626 * are holding mmap_sem. Users without mmap_sem are required to
1627 * take a reference count to prevent the anon_vma disappearing
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001628 */
1629 anon_vma = page_anon_vma(page);
1630 if (!anon_vma)
1631 return ret;
Rik van Rielcba48b92010-08-09 17:18:38 -07001632 anon_vma_lock(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -08001633 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1634 struct vm_area_struct *vma = avc->vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001635 unsigned long address = vma_address(page, vma);
1636 if (address == -EFAULT)
1637 continue;
1638 ret = rmap_one(page, vma, address, arg);
1639 if (ret != SWAP_AGAIN)
1640 break;
1641 }
Rik van Rielcba48b92010-08-09 17:18:38 -07001642 anon_vma_unlock(anon_vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001643 return ret;
1644}
1645
1646static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *,
1647 struct vm_area_struct *, unsigned long, void *), void *arg)
1648{
1649 struct address_space *mapping = page->mapping;
1650 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1651 struct vm_area_struct *vma;
1652 struct prio_tree_iter iter;
1653 int ret = SWAP_AGAIN;
1654
1655 if (!mapping)
1656 return ret;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001657 mutex_lock(&mapping->i_mmap_mutex);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001658 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1659 unsigned long address = vma_address(page, vma);
1660 if (address == -EFAULT)
1661 continue;
1662 ret = rmap_one(page, vma, address, arg);
1663 if (ret != SWAP_AGAIN)
1664 break;
1665 }
1666 /*
1667 * No nonlinear handling: being always shared, nonlinear vmas
1668 * never contain migration ptes. Decide what to do about this
1669 * limitation to linear when we need rmap_walk() on nonlinear.
1670 */
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001671 mutex_unlock(&mapping->i_mmap_mutex);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001672 return ret;
1673}
1674
1675int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
1676 struct vm_area_struct *, unsigned long, void *), void *arg)
1677{
1678 VM_BUG_ON(!PageLocked(page));
1679
1680 if (unlikely(PageKsm(page)))
1681 return rmap_walk_ksm(page, rmap_one, arg);
1682 else if (PageAnon(page))
1683 return rmap_walk_anon(page, rmap_one, arg);
1684 else
1685 return rmap_walk_file(page, rmap_one, arg);
1686}
1687#endif /* CONFIG_MIGRATION */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001688
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001689#ifdef CONFIG_HUGETLB_PAGE
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001690/*
1691 * The following three functions are for anonymous (private mapped) hugepages.
1692 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1693 * and no lru code, because we handle hugepages differently from common pages.
1694 */
1695static void __hugepage_set_anon_rmap(struct page *page,
1696 struct vm_area_struct *vma, unsigned long address, int exclusive)
1697{
1698 struct anon_vma *anon_vma = vma->anon_vma;
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001699
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001700 BUG_ON(!anon_vma);
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001701
1702 if (PageAnon(page))
1703 return;
1704 if (!exclusive)
1705 anon_vma = anon_vma->root;
1706
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001707 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1708 page->mapping = (struct address_space *) anon_vma;
1709 page->index = linear_page_index(vma, address);
1710}
1711
1712void hugepage_add_anon_rmap(struct page *page,
1713 struct vm_area_struct *vma, unsigned long address)
1714{
1715 struct anon_vma *anon_vma = vma->anon_vma;
1716 int first;
Naoya Horiguchia850ea32010-09-10 13:23:06 +09001717
1718 BUG_ON(!PageLocked(page));
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001719 BUG_ON(!anon_vma);
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001720 /* address might be in next vma when migration races vma_adjust */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001721 first = atomic_inc_and_test(&page->_mapcount);
1722 if (first)
1723 __hugepage_set_anon_rmap(page, vma, address, 0);
1724}
1725
1726void hugepage_add_new_anon_rmap(struct page *page,
1727 struct vm_area_struct *vma, unsigned long address)
1728{
1729 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1730 atomic_set(&page->_mapcount, 0);
1731 __hugepage_set_anon_rmap(page, vma, address, 1);
1732}
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001733#endif /* CONFIG_HUGETLB_PAGE */