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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 * mm->mmap_sem
25 * page->flags PG_locked (lock_page)
Peter Zijlstra3d48ae42011-05-24 17:12:06 -070026 * mapping->i_mmap_mutex
Peter Zijlstra2b575eb2011-05-24 17:12:11 -070027 * anon_vma->mutex
Nick Piggin82591e62006-10-19 23:29:10 -070028 * mm->page_table_lock or pte_lock
29 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
30 * swap_lock (in swap_duplicate, swap_info_get)
31 * mmlist_lock (in mmput, drain_mmlist and others)
32 * mapping->private_lock (in __set_page_dirty_buffers)
Dave Chinner250df6e2011-03-22 22:23:36 +110033 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
Christoph Hellwigf758eea2011-04-21 18:19:44 -060034 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
Nick Piggin82591e62006-10-19 23:29:10 -070035 * 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,
Christoph Hellwigf758eea2011-04-21 18:19:44 -060038 * within bdi.wb->list_lock in __sync_single_inode)
Andi Kleen6a460792009-09-16 11:50:15 +020039 *
Peter Zijlstra9b679322011-06-27 16:18:09 -070040 * anon_vma->mutex,mapping->i_mutex (memory_failure, collect_procs_anon)
41 * ->tasklist_lock
Andi Kleen6a460792009-09-16 11:50:15 +020042 * pte map lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070043 */
44
45#include <linux/mm.h>
46#include <linux/pagemap.h>
47#include <linux/swap.h>
48#include <linux/swapops.h>
49#include <linux/slab.h>
50#include <linux/init.h>
Hugh Dickins5ad64682009-12-14 17:59:24 -080051#include <linux/ksm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070052#include <linux/rmap.h>
53#include <linux/rcupdate.h>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040054#include <linux/export.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080055#include <linux/memcontrol.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070056#include <linux/mmu_notifier.h>
KOSAKI Motohiro64cdd542009-01-06 14:39:16 -080057#include <linux/migrate.h>
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +090058#include <linux/hugetlb.h>
Jan Karaef5d4372012-10-25 13:37:31 -070059#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070060
61#include <asm/tlbflush.h>
62
Nick Pigginb291f002008-10-18 20:26:44 -070063#include "internal.h"
64
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070065static struct kmem_cache *anon_vma_cachep;
Rik van Riel5beb4932010-03-05 13:42:07 -080066static struct kmem_cache *anon_vma_chain_cachep;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070067
68static inline struct anon_vma *anon_vma_alloc(void)
69{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070070 struct anon_vma *anon_vma;
71
72 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
73 if (anon_vma) {
74 atomic_set(&anon_vma->refcount, 1);
75 /*
76 * Initialise the anon_vma root to point to itself. If called
77 * from fork, the root will be reset to the parents anon_vma.
78 */
79 anon_vma->root = anon_vma;
80 }
81
82 return anon_vma;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070083}
84
Peter Zijlstra01d8b202011-03-22 16:32:49 -070085static inline void anon_vma_free(struct anon_vma *anon_vma)
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070086{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070087 VM_BUG_ON(atomic_read(&anon_vma->refcount));
Peter Zijlstra88c22082011-05-24 17:12:13 -070088
89 /*
90 * Synchronize against page_lock_anon_vma() such that
91 * we can safely hold the lock without the anon_vma getting
92 * freed.
93 *
94 * Relies on the full mb implied by the atomic_dec_and_test() from
95 * put_anon_vma() against the acquire barrier implied by
96 * mutex_trylock() from page_lock_anon_vma(). This orders:
97 *
98 * page_lock_anon_vma() VS put_anon_vma()
99 * mutex_trylock() atomic_dec_and_test()
100 * LOCK MB
101 * atomic_read() mutex_is_locked()
102 *
103 * LOCK should suffice since the actual taking of the lock must
104 * happen _before_ what follows.
105 */
106 if (mutex_is_locked(&anon_vma->root->mutex)) {
107 anon_vma_lock(anon_vma);
108 anon_vma_unlock(anon_vma);
109 }
110
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -0700111 kmem_cache_free(anon_vma_cachep, anon_vma);
112}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700113
Linus Torvaldsdd347392011-06-17 19:05:36 -0700114static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
Rik van Riel5beb4932010-03-05 13:42:07 -0800115{
Linus Torvaldsdd347392011-06-17 19:05:36 -0700116 return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
Rik van Riel5beb4932010-03-05 13:42:07 -0800117}
118
Namhyung Kime574b5f2010-10-26 14:22:02 -0700119static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
Rik van Riel5beb4932010-03-05 13:42:07 -0800120{
121 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
122}
123
Kautuk Consul6583a842012-03-21 16:34:01 -0700124static void anon_vma_chain_link(struct vm_area_struct *vma,
125 struct anon_vma_chain *avc,
126 struct anon_vma *anon_vma)
127{
128 avc->vma = vma;
129 avc->anon_vma = anon_vma;
130 list_add(&avc->same_vma, &vma->anon_vma_chain);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700131 anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
Kautuk Consul6583a842012-03-21 16:34:01 -0700132}
133
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700134/**
135 * anon_vma_prepare - attach an anon_vma to a memory region
136 * @vma: the memory region in question
137 *
138 * This makes sure the memory mapping described by 'vma' has
139 * an 'anon_vma' attached to it, so that we can associate the
140 * anonymous pages mapped into it with that anon_vma.
141 *
142 * The common case will be that we already have one, but if
Figo.zhang23a07902010-12-27 15:14:06 +0100143 * not we either need to find an adjacent mapping that we
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700144 * can re-use the anon_vma from (very common when the only
145 * reason for splitting a vma has been mprotect()), or we
146 * allocate a new one.
147 *
148 * Anon-vma allocations are very subtle, because we may have
149 * optimistically looked up an anon_vma in page_lock_anon_vma()
150 * and that may actually touch the spinlock even in the newly
151 * allocated vma (it depends on RCU to make sure that the
152 * anon_vma isn't actually destroyed).
153 *
154 * As a result, we need to do proper anon_vma locking even
155 * for the new allocation. At the same time, we do not want
156 * to do any locking for the common case of already having
157 * an anon_vma.
158 *
159 * This must be called with the mmap_sem held for reading.
160 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161int anon_vma_prepare(struct vm_area_struct *vma)
162{
163 struct anon_vma *anon_vma = vma->anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800164 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165
166 might_sleep();
167 if (unlikely(!anon_vma)) {
168 struct mm_struct *mm = vma->vm_mm;
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700169 struct anon_vma *allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
Linus Torvaldsdd347392011-06-17 19:05:36 -0700171 avc = anon_vma_chain_alloc(GFP_KERNEL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800172 if (!avc)
173 goto out_enomem;
174
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 anon_vma = find_mergeable_anon_vma(vma);
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700176 allocated = NULL;
177 if (!anon_vma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178 anon_vma = anon_vma_alloc();
179 if (unlikely(!anon_vma))
Rik van Riel5beb4932010-03-05 13:42:07 -0800180 goto out_enomem_free_avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 allocated = anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 }
183
Rik van Rielcba48b92010-08-09 17:18:38 -0700184 anon_vma_lock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 /* page_table_lock to protect against threads */
186 spin_lock(&mm->page_table_lock);
187 if (likely(!vma->anon_vma)) {
188 vma->anon_vma = anon_vma;
Kautuk Consul6583a842012-03-21 16:34:01 -0700189 anon_vma_chain_link(vma, avc, anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 allocated = NULL;
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400191 avc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 }
193 spin_unlock(&mm->page_table_lock);
Rik van Rielcba48b92010-08-09 17:18:38 -0700194 anon_vma_unlock(anon_vma);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400195
196 if (unlikely(allocated))
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700197 put_anon_vma(allocated);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400198 if (unlikely(avc))
Rik van Riel5beb4932010-03-05 13:42:07 -0800199 anon_vma_chain_free(avc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700200 }
201 return 0;
Rik van Riel5beb4932010-03-05 13:42:07 -0800202
203 out_enomem_free_avc:
204 anon_vma_chain_free(avc);
205 out_enomem:
206 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207}
208
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700209/*
210 * This is a useful helper function for locking the anon_vma root as
211 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
212 * have the same vma.
213 *
214 * Such anon_vma's should have the same root, so you'd expect to see
215 * just a single mutex_lock for the whole traversal.
216 */
217static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
218{
219 struct anon_vma *new_root = anon_vma->root;
220 if (new_root != root) {
221 if (WARN_ON_ONCE(root))
222 mutex_unlock(&root->mutex);
223 root = new_root;
224 mutex_lock(&root->mutex);
225 }
226 return root;
227}
228
229static inline void unlock_anon_vma_root(struct anon_vma *root)
230{
231 if (root)
232 mutex_unlock(&root->mutex);
233}
234
Rik van Riel5beb4932010-03-05 13:42:07 -0800235/*
236 * Attach the anon_vmas from src to dst.
237 * Returns 0 on success, -ENOMEM on failure.
238 */
239int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700240{
Rik van Riel5beb4932010-03-05 13:42:07 -0800241 struct anon_vma_chain *avc, *pavc;
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700242 struct anon_vma *root = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700243
Linus Torvalds646d87b2010-04-11 17:15:03 -0700244 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700245 struct anon_vma *anon_vma;
246
Linus Torvaldsdd347392011-06-17 19:05:36 -0700247 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
248 if (unlikely(!avc)) {
249 unlock_anon_vma_root(root);
250 root = NULL;
251 avc = anon_vma_chain_alloc(GFP_KERNEL);
252 if (!avc)
253 goto enomem_failure;
254 }
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700255 anon_vma = pavc->anon_vma;
256 root = lock_anon_vma_root(root, anon_vma);
257 anon_vma_chain_link(dst, avc, anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700258 }
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700259 unlock_anon_vma_root(root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800260 return 0;
261
262 enomem_failure:
263 unlink_anon_vmas(dst);
264 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265}
266
Rik van Riel5beb4932010-03-05 13:42:07 -0800267/*
268 * Attach vma to its own anon_vma, as well as to the anon_vmas that
269 * the corresponding VMA in the parent process is attached to.
270 * Returns 0 on success, non-zero on failure.
271 */
272int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273{
Rik van Riel5beb4932010-03-05 13:42:07 -0800274 struct anon_vma_chain *avc;
275 struct anon_vma *anon_vma;
276
277 /* Don't bother if the parent process has no anon_vma here. */
278 if (!pvma->anon_vma)
279 return 0;
280
281 /*
282 * First, attach the new VMA to the parent VMA's anon_vmas,
283 * so rmap can find non-COWed pages in child processes.
284 */
285 if (anon_vma_clone(vma, pvma))
286 return -ENOMEM;
287
288 /* Then add our own anon_vma. */
289 anon_vma = anon_vma_alloc();
290 if (!anon_vma)
291 goto out_error;
Linus Torvaldsdd347392011-06-17 19:05:36 -0700292 avc = anon_vma_chain_alloc(GFP_KERNEL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800293 if (!avc)
294 goto out_error_free_anon_vma;
Rik van Riel5c341ee12010-08-09 17:18:39 -0700295
296 /*
297 * The root anon_vma's spinlock is the lock actually used when we
298 * lock any of the anon_vmas in this anon_vma tree.
299 */
300 anon_vma->root = pvma->anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -0700301 /*
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700302 * With refcounts, an anon_vma can stay around longer than the
303 * process it belongs to. The root anon_vma needs to be pinned until
304 * this anon_vma is freed, because the lock lives in the root.
Rik van Riel76545062010-08-09 17:18:41 -0700305 */
306 get_anon_vma(anon_vma->root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800307 /* Mark this anon_vma as the one where our new (COWed) pages go. */
308 vma->anon_vma = anon_vma;
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700309 anon_vma_lock(anon_vma);
Rik van Riel5c341ee12010-08-09 17:18:39 -0700310 anon_vma_chain_link(vma, avc, anon_vma);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700311 anon_vma_unlock(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800312
313 return 0;
314
315 out_error_free_anon_vma:
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700316 put_anon_vma(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800317 out_error:
Rik van Riel4946d542010-04-05 12:13:33 -0400318 unlink_anon_vmas(vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800319 return -ENOMEM;
320}
321
Rik van Riel5beb4932010-03-05 13:42:07 -0800322void unlink_anon_vmas(struct vm_area_struct *vma)
323{
324 struct anon_vma_chain *avc, *next;
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200325 struct anon_vma *root = NULL;
Rik van Riel5beb4932010-03-05 13:42:07 -0800326
Rik van Riel5c341ee12010-08-09 17:18:39 -0700327 /*
328 * Unlink each anon_vma chained to the VMA. This list is ordered
329 * from newest to oldest, ensuring the root anon_vma gets freed last.
330 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800331 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200332 struct anon_vma *anon_vma = avc->anon_vma;
333
334 root = lock_anon_vma_root(root, anon_vma);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700335 anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200336
337 /*
338 * Leave empty anon_vmas on the list - we'll need
339 * to free them outside the lock.
340 */
Michel Lespinassebf181b92012-10-08 16:31:39 -0700341 if (RB_EMPTY_ROOT(&anon_vma->rb_root))
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200342 continue;
343
344 list_del(&avc->same_vma);
345 anon_vma_chain_free(avc);
346 }
347 unlock_anon_vma_root(root);
348
349 /*
350 * Iterate the list once more, it now only contains empty and unlinked
351 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
352 * needing to acquire the anon_vma->root->mutex.
353 */
354 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
355 struct anon_vma *anon_vma = avc->anon_vma;
356
357 put_anon_vma(anon_vma);
358
Rik van Riel5beb4932010-03-05 13:42:07 -0800359 list_del(&avc->same_vma);
360 anon_vma_chain_free(avc);
361 }
362}
363
Alexey Dobriyan51cc5062008-07-25 19:45:34 -0700364static void anon_vma_ctor(void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365{
Christoph Lametera35afb82007-05-16 22:10:57 -0700366 struct anon_vma *anon_vma = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367
Peter Zijlstra2b575eb2011-05-24 17:12:11 -0700368 mutex_init(&anon_vma->mutex);
Peter Zijlstra83813262011-03-22 16:32:48 -0700369 atomic_set(&anon_vma->refcount, 0);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700370 anon_vma->rb_root = RB_ROOT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371}
372
373void __init anon_vma_init(void)
374{
375 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
Paul Mundt20c2df82007-07-20 10:11:58 +0900376 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
Rik van Riel5beb4932010-03-05 13:42:07 -0800377 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378}
379
380/*
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700381 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
382 *
383 * Since there is no serialization what so ever against page_remove_rmap()
384 * the best this function can do is return a locked anon_vma that might
385 * have been relevant to this page.
386 *
387 * The page might have been remapped to a different anon_vma or the anon_vma
388 * returned may already be freed (and even reused).
389 *
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200390 * In case it was remapped to a different anon_vma, the new anon_vma will be a
391 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
392 * ensure that any anon_vma obtained from the page will still be valid for as
393 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
394 *
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700395 * All users of this function must be very careful when walking the anon_vma
396 * chain and verify that the page in question is indeed mapped in it
397 * [ something equivalent to page_mapped_in_vma() ].
398 *
399 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
400 * that the anon_vma pointer from page->mapping is valid if there is a
401 * mapcount, we can dereference the anon_vma after observing those.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700402 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700403struct anon_vma *page_get_anon_vma(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404{
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700405 struct anon_vma *anon_vma = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700406 unsigned long anon_mapping;
407
408 rcu_read_lock();
Hugh Dickins80e148222009-12-14 17:59:29 -0800409 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800410 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700411 goto out;
412 if (!page_mapped(page))
413 goto out;
414
415 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700416 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
417 anon_vma = NULL;
418 goto out;
419 }
Hugh Dickinsf18194272010-08-25 23:12:54 -0700420
421 /*
422 * If this page is still mapped, then its anon_vma cannot have been
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700423 * freed. But if it has been unmapped, we have no security against the
424 * anon_vma structure being freed and reused (for another anon_vma:
425 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
426 * above cannot corrupt).
Hugh Dickinsf18194272010-08-25 23:12:54 -0700427 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700428 if (!page_mapped(page)) {
429 put_anon_vma(anon_vma);
430 anon_vma = NULL;
431 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432out:
433 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700434
435 return anon_vma;
436}
437
Peter Zijlstra88c22082011-05-24 17:12:13 -0700438/*
439 * Similar to page_get_anon_vma() except it locks the anon_vma.
440 *
441 * Its a little more complex as it tries to keep the fast path to a single
442 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
443 * reference like with page_get_anon_vma() and then block on the mutex.
444 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700445struct anon_vma *page_lock_anon_vma(struct page *page)
446{
Peter Zijlstra88c22082011-05-24 17:12:13 -0700447 struct anon_vma *anon_vma = NULL;
Hugh Dickinseee0f252011-05-28 13:20:21 -0700448 struct anon_vma *root_anon_vma;
Peter Zijlstra88c22082011-05-24 17:12:13 -0700449 unsigned long anon_mapping;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700450
Peter Zijlstra88c22082011-05-24 17:12:13 -0700451 rcu_read_lock();
452 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
453 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
454 goto out;
455 if (!page_mapped(page))
456 goto out;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700457
Peter Zijlstra88c22082011-05-24 17:12:13 -0700458 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Hugh Dickinseee0f252011-05-28 13:20:21 -0700459 root_anon_vma = ACCESS_ONCE(anon_vma->root);
460 if (mutex_trylock(&root_anon_vma->mutex)) {
Peter Zijlstra88c22082011-05-24 17:12:13 -0700461 /*
Hugh Dickinseee0f252011-05-28 13:20:21 -0700462 * If the page is still mapped, then this anon_vma is still
463 * its anon_vma, and holding the mutex ensures that it will
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200464 * not go away, see anon_vma_free().
Peter Zijlstra88c22082011-05-24 17:12:13 -0700465 */
Hugh Dickinseee0f252011-05-28 13:20:21 -0700466 if (!page_mapped(page)) {
467 mutex_unlock(&root_anon_vma->mutex);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700468 anon_vma = NULL;
469 }
470 goto out;
471 }
472
473 /* trylock failed, we got to sleep */
474 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
475 anon_vma = NULL;
476 goto out;
477 }
478
479 if (!page_mapped(page)) {
480 put_anon_vma(anon_vma);
481 anon_vma = NULL;
482 goto out;
483 }
484
485 /* we pinned the anon_vma, its safe to sleep */
486 rcu_read_unlock();
487 anon_vma_lock(anon_vma);
488
489 if (atomic_dec_and_test(&anon_vma->refcount)) {
490 /*
491 * Oops, we held the last refcount, release the lock
492 * and bail -- can't simply use put_anon_vma() because
493 * we'll deadlock on the anon_vma_lock() recursion.
494 */
495 anon_vma_unlock(anon_vma);
496 __put_anon_vma(anon_vma);
497 anon_vma = NULL;
498 }
499
500 return anon_vma;
501
502out:
503 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700504 return anon_vma;
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800505}
506
Andi Kleen10be22d2009-09-16 11:50:04 +0200507void page_unlock_anon_vma(struct anon_vma *anon_vma)
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800508{
Rik van Rielcba48b92010-08-09 17:18:38 -0700509 anon_vma_unlock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700510}
511
512/*
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800513 * At what user virtual address is page expected in @vma?
Linus Torvalds1da177e2005-04-16 15:20:36 -0700514 */
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700515static inline unsigned long
516__vma_address(struct page *page, struct vm_area_struct *vma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700517{
518 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900520 if (unlikely(is_vm_hugetlb_page(vma)))
521 pgoff = page->index << huge_page_order(page_hstate(page));
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700522
523 return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
524}
525
526inline unsigned long
527vma_address(struct page *page, struct vm_area_struct *vma)
528{
529 unsigned long address = __vma_address(page, vma);
530
531 /* page should be within @vma mapping range */
532 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
533
Linus Torvalds1da177e2005-04-16 15:20:36 -0700534 return address;
535}
536
537/*
Huang Shijiebf89c8c2009-10-01 15:44:04 -0700538 * At what user virtual address is page expected in vma?
Naoya Horiguchiab941e02010-05-11 14:06:55 -0700539 * Caller should check the page is actually part of the vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700540 */
541unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
542{
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700543 unsigned long address;
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700544 if (PageAnon(page)) {
Hugh Dickins4829b902010-10-02 17:46:06 -0700545 struct anon_vma *page__anon_vma = page_anon_vma(page);
546 /*
547 * Note: swapoff's unuse_vma() is more efficient with this
548 * check, and needs it to match anon_vma when KSM is active.
549 */
550 if (!vma->anon_vma || !page__anon_vma ||
551 vma->anon_vma->root != page__anon_vma->root)
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700552 return -EFAULT;
553 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800554 if (!vma->vm_file ||
555 vma->vm_file->f_mapping != page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700556 return -EFAULT;
557 } else
558 return -EFAULT;
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700559 address = __vma_address(page, vma);
560 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
561 return -EFAULT;
562 return address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700563}
564
565/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700566 * Check that @page is mapped at @address into @mm.
567 *
Nick Piggin479db0b2008-08-20 14:09:18 -0700568 * If @sync is false, page_check_address may perform a racy check to avoid
569 * the page table lock when the pte is not present (helpful when reclaiming
570 * highly shared pages).
571 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700572 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700573 */
Namhyung Kime9a81a82010-10-26 14:22:01 -0700574pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
Nick Piggin479db0b2008-08-20 14:09:18 -0700575 unsigned long address, spinlock_t **ptlp, int sync)
Nikita Danilov81b40822005-05-01 08:58:36 -0700576{
577 pgd_t *pgd;
578 pud_t *pud;
579 pmd_t *pmd;
580 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700581 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700582
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900583 if (unlikely(PageHuge(page))) {
584 pte = huge_pte_offset(mm, address);
585 ptl = &mm->page_table_lock;
586 goto check;
587 }
588
Nikita Danilov81b40822005-05-01 08:58:36 -0700589 pgd = pgd_offset(mm, address);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700590 if (!pgd_present(*pgd))
591 return NULL;
592
593 pud = pud_offset(pgd, address);
594 if (!pud_present(*pud))
595 return NULL;
596
597 pmd = pmd_offset(pud, address);
598 if (!pmd_present(*pmd))
599 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800600 if (pmd_trans_huge(*pmd))
601 return NULL;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700602
603 pte = pte_offset_map(pmd, address);
604 /* Make a quick check before getting the lock */
Nick Piggin479db0b2008-08-20 14:09:18 -0700605 if (!sync && !pte_present(*pte)) {
Hugh Dickinsc0718802005-10-29 18:16:31 -0700606 pte_unmap(pte);
607 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700608 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700609
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700610 ptl = pte_lockptr(mm, pmd);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900611check:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700612 spin_lock(ptl);
613 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
614 *ptlp = ptl;
615 return pte;
616 }
617 pte_unmap_unlock(pte, ptl);
618 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700619}
620
Nick Pigginb291f002008-10-18 20:26:44 -0700621/**
622 * page_mapped_in_vma - check whether a page is really mapped in a VMA
623 * @page: the page to test
624 * @vma: the VMA to test
625 *
626 * Returns 1 if the page is mapped into the page tables of the VMA, 0
627 * if the page is not mapped into the page tables of this VMA. Only
628 * valid for normal file or anonymous VMAs.
629 */
Andi Kleen6a460792009-09-16 11:50:15 +0200630int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
Nick Pigginb291f002008-10-18 20:26:44 -0700631{
632 unsigned long address;
633 pte_t *pte;
634 spinlock_t *ptl;
635
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700636 address = __vma_address(page, vma);
637 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
Nick Pigginb291f002008-10-18 20:26:44 -0700638 return 0;
639 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
640 if (!pte) /* the page is not in this mm */
641 return 0;
642 pte_unmap_unlock(pte, ptl);
643
644 return 1;
645}
646
Nikita Danilov81b40822005-05-01 08:58:36 -0700647/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700648 * Subfunctions of page_referenced: page_referenced_one called
649 * repeatedly from either page_referenced_anon or page_referenced_file.
650 */
Hugh Dickins5ad64682009-12-14 17:59:24 -0800651int page_referenced_one(struct page *page, struct vm_area_struct *vma,
652 unsigned long address, unsigned int *mapcount,
653 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700654{
655 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700656 int referenced = 0;
657
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800658 if (unlikely(PageTransHuge(page))) {
659 pmd_t *pmd;
660
661 spin_lock(&mm->page_table_lock);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800662 /*
663 * rmap might return false positives; we must filter
664 * these out using page_check_address_pmd().
665 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800666 pmd = page_check_address_pmd(page, mm, address,
667 PAGE_CHECK_ADDRESS_PMD_FLAG);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800668 if (!pmd) {
669 spin_unlock(&mm->page_table_lock);
670 goto out;
671 }
672
673 if (vma->vm_flags & VM_LOCKED) {
674 spin_unlock(&mm->page_table_lock);
675 *mapcount = 0; /* break early from loop */
676 *vm_flags |= VM_LOCKED;
677 goto out;
678 }
679
680 /* go ahead even if the pmd is pmd_trans_splitting() */
681 if (pmdp_clear_flush_young_notify(vma, address, pmd))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800682 referenced++;
683 spin_unlock(&mm->page_table_lock);
684 } else {
685 pte_t *pte;
686 spinlock_t *ptl;
687
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800688 /*
689 * rmap might return false positives; we must filter
690 * these out using page_check_address().
691 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800692 pte = page_check_address(page, mm, address, &ptl, 0);
693 if (!pte)
694 goto out;
695
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800696 if (vma->vm_flags & VM_LOCKED) {
697 pte_unmap_unlock(pte, ptl);
698 *mapcount = 0; /* break early from loop */
699 *vm_flags |= VM_LOCKED;
700 goto out;
701 }
702
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800703 if (ptep_clear_flush_young_notify(vma, address, pte)) {
704 /*
705 * Don't treat a reference through a sequentially read
706 * mapping as such. If the page has been used in
707 * another mapping, we will catch it; if this other
708 * mapping is already gone, the unmap path will have
709 * set PG_referenced or activated the page.
710 */
711 if (likely(!VM_SequentialReadHint(vma)))
712 referenced++;
713 }
714 pte_unmap_unlock(pte, ptl);
715 }
716
Hugh Dickinsc0718802005-10-29 18:16:31 -0700717 (*mapcount)--;
Huang Shijie273f0472009-12-14 17:58:51 -0800718
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700719 if (referenced)
720 *vm_flags |= vma->vm_flags;
Huang Shijie273f0472009-12-14 17:58:51 -0800721out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700722 return referenced;
723}
724
Balbir Singhbed71612008-02-07 00:14:01 -0800725static int page_referenced_anon(struct page *page,
Johannes Weiner72835c82012-01-12 17:18:32 -0800726 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700727 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728{
729 unsigned int mapcount;
730 struct anon_vma *anon_vma;
Michel Lespinassebf181b92012-10-08 16:31:39 -0700731 pgoff_t pgoff;
Rik van Riel5beb4932010-03-05 13:42:07 -0800732 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700733 int referenced = 0;
734
735 anon_vma = page_lock_anon_vma(page);
736 if (!anon_vma)
737 return referenced;
738
739 mapcount = page_mapcount(page);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700740 pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
741 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -0800742 struct vm_area_struct *vma = avc->vma;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800743 unsigned long address = vma_address(page, vma);
Balbir Singhbed71612008-02-07 00:14:01 -0800744 /*
745 * If we are reclaiming on behalf of a cgroup, skip
746 * counting on behalf of references from different
747 * cgroups
748 */
Johannes Weiner72835c82012-01-12 17:18:32 -0800749 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
Balbir Singhbed71612008-02-07 00:14:01 -0800750 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800751 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700752 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700753 if (!mapcount)
754 break;
755 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800756
757 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700758 return referenced;
759}
760
761/**
762 * page_referenced_file - referenced check for object-based rmap
763 * @page: the page we're checking references on.
Johannes Weiner72835c82012-01-12 17:18:32 -0800764 * @memcg: target memory control group
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700765 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700766 *
767 * For an object-based mapped page, find all the places it is mapped and
768 * check/clear the referenced flag. This is done by following the page->mapping
769 * pointer, then walking the chain of vmas it holds. It returns the number
770 * of references it found.
771 *
772 * This function is only called from page_referenced for object-based pages.
773 */
Balbir Singhbed71612008-02-07 00:14:01 -0800774static int page_referenced_file(struct page *page,
Johannes Weiner72835c82012-01-12 17:18:32 -0800775 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700776 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700777{
778 unsigned int mapcount;
779 struct address_space *mapping = page->mapping;
780 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
781 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700782 int referenced = 0;
783
784 /*
785 * The caller's checks on page->mapping and !PageAnon have made
786 * sure that this is a file page: the check for page->mapping
787 * excludes the case just before it gets set on an anon page.
788 */
789 BUG_ON(PageAnon(page));
790
791 /*
792 * The page lock not only makes sure that page->mapping cannot
793 * suddenly be NULLified by truncation, it makes sure that the
794 * structure at mapping cannot be freed and reused yet,
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700795 * so we can safely take mapping->i_mmap_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700796 */
797 BUG_ON(!PageLocked(page));
798
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700799 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700800
801 /*
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700802 * i_mmap_mutex does not stabilize mapcount at all, but mapcount
Linus Torvalds1da177e2005-04-16 15:20:36 -0700803 * is more likely to be accurate if we note it after spinning.
804 */
805 mapcount = page_mapcount(page);
806
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -0700807 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800808 unsigned long address = vma_address(page, vma);
Balbir Singhbed71612008-02-07 00:14:01 -0800809 /*
810 * If we are reclaiming on behalf of a cgroup, skip
811 * counting on behalf of references from different
812 * cgroups
813 */
Johannes Weiner72835c82012-01-12 17:18:32 -0800814 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
Balbir Singhbed71612008-02-07 00:14:01 -0800815 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800816 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700817 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818 if (!mapcount)
819 break;
820 }
821
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700822 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700823 return referenced;
824}
825
826/**
827 * page_referenced - test if the page was referenced
828 * @page: the page to test
829 * @is_locked: caller holds lock on the page
Johannes Weiner72835c82012-01-12 17:18:32 -0800830 * @memcg: target memory cgroup
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700831 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700832 *
833 * Quick test_and_clear_referenced for all mappings to a page,
834 * returns the number of ptes which referenced the page.
835 */
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700836int page_referenced(struct page *page,
837 int is_locked,
Johannes Weiner72835c82012-01-12 17:18:32 -0800838 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700839 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700840{
841 int referenced = 0;
Hugh Dickins5ad64682009-12-14 17:59:24 -0800842 int we_locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700843
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700844 *vm_flags = 0;
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800845 if (page_mapped(page) && page_rmapping(page)) {
Hugh Dickins5ad64682009-12-14 17:59:24 -0800846 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
847 we_locked = trylock_page(page);
848 if (!we_locked) {
849 referenced++;
850 goto out;
851 }
852 }
853 if (unlikely(PageKsm(page)))
Johannes Weiner72835c82012-01-12 17:18:32 -0800854 referenced += page_referenced_ksm(page, memcg,
Hugh Dickins5ad64682009-12-14 17:59:24 -0800855 vm_flags);
856 else if (PageAnon(page))
Johannes Weiner72835c82012-01-12 17:18:32 -0800857 referenced += page_referenced_anon(page, memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700858 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800859 else if (page->mapping)
Johannes Weiner72835c82012-01-12 17:18:32 -0800860 referenced += page_referenced_file(page, memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700861 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800862 if (we_locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700863 unlock_page(page);
Martin Schwidefsky50a15982011-07-24 10:47:59 +0200864
865 if (page_test_and_clear_young(page_to_pfn(page)))
866 referenced++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 }
Hugh Dickins5ad64682009-12-14 17:59:24 -0800868out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700869 return referenced;
870}
871
Hugh Dickins1cb17292009-12-14 17:59:01 -0800872static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
873 unsigned long address)
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700874{
875 struct mm_struct *mm = vma->vm_mm;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100876 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700877 spinlock_t *ptl;
878 int ret = 0;
879
Nick Piggin479db0b2008-08-20 14:09:18 -0700880 pte = page_check_address(page, mm, address, &ptl, 1);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700881 if (!pte)
882 goto out;
883
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100884 if (pte_dirty(*pte) || pte_write(*pte)) {
885 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700886
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100887 flush_cache_page(vma, address, pte_pfn(*pte));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700888 entry = ptep_clear_flush(vma, address, pte);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100889 entry = pte_wrprotect(entry);
890 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -0800891 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100892 ret = 1;
893 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700894
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700895 pte_unmap_unlock(pte, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700896
897 if (ret)
898 mmu_notifier_invalidate_page(mm, address);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700899out:
900 return ret;
901}
902
903static int page_mkclean_file(struct address_space *mapping, struct page *page)
904{
905 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
906 struct vm_area_struct *vma;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700907 int ret = 0;
908
909 BUG_ON(PageAnon(page));
910
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700911 mutex_lock(&mapping->i_mmap_mutex);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -0700912 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800913 if (vma->vm_flags & VM_SHARED) {
914 unsigned long address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -0800915 ret += page_mkclean_one(page, vma, address);
916 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700917 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700918 mutex_unlock(&mapping->i_mmap_mutex);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700919 return ret;
920}
921
922int page_mkclean(struct page *page)
923{
924 int ret = 0;
925
926 BUG_ON(!PageLocked(page));
927
928 if (page_mapped(page)) {
929 struct address_space *mapping = page_mapping(page);
Jan Karaef5d4372012-10-25 13:37:31 -0700930 if (mapping)
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700931 ret = page_mkclean_file(mapping, page);
932 }
933
934 return ret;
935}
Jaya Kumar60b59be2007-05-08 00:37:37 -0700936EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700937
Linus Torvalds1da177e2005-04-16 15:20:36 -0700938/**
Rik van Rielc44b6742010-03-05 13:42:09 -0800939 * page_move_anon_rmap - move a page to our anon_vma
940 * @page: the page to move to our anon_vma
941 * @vma: the vma the page belongs to
942 * @address: the user virtual address mapped
943 *
944 * When a page belongs exclusively to one process after a COW event,
945 * that page can be moved into the anon_vma that belongs to just that
946 * process, so the rmap code will not search the parent or sibling
947 * processes.
948 */
949void page_move_anon_rmap(struct page *page,
950 struct vm_area_struct *vma, unsigned long address)
951{
952 struct anon_vma *anon_vma = vma->anon_vma;
953
954 VM_BUG_ON(!PageLocked(page));
955 VM_BUG_ON(!anon_vma);
956 VM_BUG_ON(page->index != linear_page_index(vma, address));
957
958 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
959 page->mapping = (struct address_space *) anon_vma;
960}
961
962/**
Andi Kleen4e1c1972010-09-22 12:43:56 +0200963 * __page_set_anon_rmap - set up new anonymous rmap
964 * @page: Page to add to rmap
965 * @vma: VM area to add page to.
966 * @address: User virtual address of the mapping
Rik van Riele8a03fe2010-04-14 17:59:28 -0400967 * @exclusive: the page is exclusively owned by the current process
Nick Piggin9617d952006-01-06 00:11:12 -0800968 */
969static void __page_set_anon_rmap(struct page *page,
Rik van Riele8a03fe2010-04-14 17:59:28 -0400970 struct vm_area_struct *vma, unsigned long address, int exclusive)
Nick Piggin9617d952006-01-06 00:11:12 -0800971{
Rik van Riele8a03fe2010-04-14 17:59:28 -0400972 struct anon_vma *anon_vma = vma->anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -0800973
Rik van Riele8a03fe2010-04-14 17:59:28 -0400974 BUG_ON(!anon_vma);
Linus Torvaldsea900022010-04-12 12:44:29 -0700975
Andi Kleen4e1c1972010-09-22 12:43:56 +0200976 if (PageAnon(page))
977 return;
978
Linus Torvaldsea900022010-04-12 12:44:29 -0700979 /*
Rik van Riele8a03fe2010-04-14 17:59:28 -0400980 * If the page isn't exclusively mapped into this vma,
981 * we must use the _oldest_ possible anon_vma for the
982 * page mapping!
Linus Torvaldsea900022010-04-12 12:44:29 -0700983 */
Andi Kleen4e1c1972010-09-22 12:43:56 +0200984 if (!exclusive)
Andrea Arcangeli288468c2010-08-09 17:19:09 -0700985 anon_vma = anon_vma->root;
Linus Torvaldsea900022010-04-12 12:44:29 -0700986
Nick Piggin9617d952006-01-06 00:11:12 -0800987 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
988 page->mapping = (struct address_space *) anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -0800989 page->index = linear_page_index(vma, address);
Nick Piggin9617d952006-01-06 00:11:12 -0800990}
991
992/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -0700993 * __page_check_anon_rmap - sanity check anonymous rmap addition
Nick Pigginc97a9e12007-05-16 22:11:21 -0700994 * @page: the page to add the mapping to
995 * @vma: the vm area in which the mapping is added
996 * @address: the user virtual address mapped
997 */
998static void __page_check_anon_rmap(struct page *page,
999 struct vm_area_struct *vma, unsigned long address)
1000{
1001#ifdef CONFIG_DEBUG_VM
1002 /*
1003 * The page's anon-rmap details (mapping and index) are guaranteed to
1004 * be set up correctly at this point.
1005 *
1006 * We have exclusion against page_add_anon_rmap because the caller
1007 * always holds the page locked, except if called from page_dup_rmap,
1008 * in which case the page is already known to be setup.
1009 *
1010 * We have exclusion against page_add_new_anon_rmap because those pages
1011 * are initially only visible via the pagetables, and the pte is locked
1012 * over the call to page_add_new_anon_rmap.
1013 */
Andrea Arcangeli44ab57a2010-08-09 17:19:10 -07001014 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
Nick Pigginc97a9e12007-05-16 22:11:21 -07001015 BUG_ON(page->index != linear_page_index(vma, address));
1016#endif
1017}
1018
1019/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001020 * page_add_anon_rmap - add pte mapping to an anonymous page
1021 * @page: the page to add the mapping to
1022 * @vma: the vm area in which the mapping is added
1023 * @address: the user virtual address mapped
1024 *
Hugh Dickins5ad64682009-12-14 17:59:24 -08001025 * The caller needs to hold the pte lock, and the page must be locked in
Hugh Dickins80e148222009-12-14 17:59:29 -08001026 * the anon_vma case: to serialize mapping,index checking after setting,
1027 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1028 * (but PageKsm is never downgraded to PageAnon).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 */
1030void page_add_anon_rmap(struct page *page,
1031 struct vm_area_struct *vma, unsigned long address)
1032{
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001033 do_page_add_anon_rmap(page, vma, address, 0);
1034}
1035
1036/*
1037 * Special version of the above for do_swap_page, which often runs
1038 * into pages that are exclusively owned by the current process.
1039 * Everybody else should continue to use page_add_anon_rmap above.
1040 */
1041void do_page_add_anon_rmap(struct page *page,
1042 struct vm_area_struct *vma, unsigned long address, int exclusive)
1043{
Hugh Dickins5ad64682009-12-14 17:59:24 -08001044 int first = atomic_inc_and_test(&page->_mapcount);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001045 if (first) {
1046 if (!PageTransHuge(page))
1047 __inc_zone_page_state(page, NR_ANON_PAGES);
1048 else
1049 __inc_zone_page_state(page,
1050 NR_ANON_TRANSPARENT_HUGEPAGES);
1051 }
Hugh Dickins5ad64682009-12-14 17:59:24 -08001052 if (unlikely(PageKsm(page)))
1053 return;
1054
Nick Pigginc97a9e12007-05-16 22:11:21 -07001055 VM_BUG_ON(!PageLocked(page));
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001056 /* address might be in next vma when migration races vma_adjust */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001057 if (first)
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001058 __page_set_anon_rmap(page, vma, address, exclusive);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001059 else
Nick Pigginc97a9e12007-05-16 22:11:21 -07001060 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001061}
1062
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001063/**
Nick Piggin9617d952006-01-06 00:11:12 -08001064 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1065 * @page: the page to add the mapping to
1066 * @vma: the vm area in which the mapping is added
1067 * @address: the user virtual address mapped
1068 *
1069 * Same as page_add_anon_rmap but must only be called on *new* pages.
1070 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -07001071 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -08001072 */
1073void page_add_new_anon_rmap(struct page *page,
1074 struct vm_area_struct *vma, unsigned long address)
1075{
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001076 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001077 SetPageSwapBacked(page);
1078 atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
Andrea Arcangeli79134172011-01-13 15:46:58 -08001079 if (!PageTransHuge(page))
1080 __inc_zone_page_state(page, NR_ANON_PAGES);
1081 else
1082 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
Rik van Riele8a03fe2010-04-14 17:59:28 -04001083 __page_set_anon_rmap(page, vma, address, 1);
Hugh Dickins39b5f292012-10-08 16:33:18 -07001084 if (!mlocked_vma_newpage(vma, page))
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001085 lru_cache_add_lru(page, LRU_ACTIVE_ANON);
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001086 else
1087 add_page_to_unevictable_list(page);
Nick Piggin9617d952006-01-06 00:11:12 -08001088}
1089
Linus Torvalds1da177e2005-04-16 15:20:36 -07001090/**
1091 * page_add_file_rmap - add pte mapping to a file page
1092 * @page: the page to add the mapping to
1093 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001094 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001095 */
1096void page_add_file_rmap(struct page *page)
1097{
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001098 bool locked;
1099 unsigned long flags;
1100
1101 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
Balbir Singhd69b0422009-06-17 16:26:34 -07001102 if (atomic_inc_and_test(&page->_mapcount)) {
Christoph Lameter65ba55f2006-06-30 01:55:34 -07001103 __inc_zone_page_state(page, NR_FILE_MAPPED);
Greg Thelen2a7106f2011-01-13 15:47:37 -08001104 mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED);
Balbir Singhd69b0422009-06-17 16:26:34 -07001105 }
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001106 mem_cgroup_end_update_page_stat(page, &locked, &flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001107}
1108
1109/**
1110 * page_remove_rmap - take down pte mapping from a page
1111 * @page: page to remove mapping from
1112 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001113 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001114 */
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001115void page_remove_rmap(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001116{
Jan Karaef5d4372012-10-25 13:37:31 -07001117 struct address_space *mapping = page_mapping(page);
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001118 bool anon = PageAnon(page);
1119 bool locked;
1120 unsigned long flags;
1121
1122 /*
1123 * The anon case has no mem_cgroup page_stat to update; but may
1124 * uncharge_page() below, where the lock ordering can deadlock if
1125 * we hold the lock against page_stat move: so avoid it on anon.
1126 */
1127 if (!anon)
1128 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
1129
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001130 /* page still mapped by someone else? */
1131 if (!atomic_add_negative(-1, &page->_mapcount))
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001132 goto out;
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001133
1134 /*
1135 * Now that the last pte has gone, s390 must transfer dirty
1136 * flag from storage key to struct page. We can usually skip
1137 * this if the page is anon, so about to be freed; but perhaps
1138 * not if it's in swapcache - there might be another pte slot
1139 * containing the swap entry, but page not yet written to swap.
Jan Karaef5d4372012-10-25 13:37:31 -07001140 *
1141 * And we can skip it on file pages, so long as the filesystem
1142 * participates in dirty tracking; but need to catch shm and tmpfs
1143 * and ramfs pages which have been modified since creation by read
1144 * fault.
1145 *
1146 * Note that mapping must be decided above, before decrementing
1147 * mapcount (which luckily provides a barrier): once page is unmapped,
1148 * it could be truncated and page->mapping reset to NULL at any moment.
1149 * Note also that we are relying on page_mapping(page) to set mapping
1150 * to &swapper_space when PageSwapCache(page).
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001151 */
Jan Karaef5d4372012-10-25 13:37:31 -07001152 if (mapping && !mapping_cap_account_dirty(mapping) &&
Martin Schwidefsky2d425522011-05-23 10:24:39 +02001153 page_test_and_clear_dirty(page_to_pfn(page), 1))
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001154 set_page_dirty(page);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001155 /*
1156 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
1157 * and not charged by memcg for now.
1158 */
1159 if (unlikely(PageHuge(page)))
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001160 goto out;
1161 if (anon) {
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001162 mem_cgroup_uncharge_page(page);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001163 if (!PageTransHuge(page))
1164 __dec_zone_page_state(page, NR_ANON_PAGES);
1165 else
1166 __dec_zone_page_state(page,
1167 NR_ANON_TRANSPARENT_HUGEPAGES);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001168 } else {
1169 __dec_zone_page_state(page, NR_FILE_MAPPED);
Greg Thelen2a7106f2011-01-13 15:47:37 -08001170 mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED);
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001171 mem_cgroup_end_update_page_stat(page, &locked, &flags);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001172 }
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001173 if (unlikely(PageMlocked(page)))
1174 clear_page_mlock(page);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001175 /*
1176 * It would be tidy to reset the PageAnon mapping here,
1177 * but that might overwrite a racing page_add_anon_rmap
1178 * which increments mapcount after us but sets mapping
1179 * before us: so leave the reset to free_hot_cold_page,
1180 * and remember that it's only reliable while mapped.
1181 * Leaving it set also helps swapoff to reinstate ptes
1182 * faster for those pages still in swapcache.
1183 */
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001184 return;
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001185out:
1186 if (!anon)
1187 mem_cgroup_end_update_page_stat(page, &locked, &flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001188}
1189
1190/*
1191 * Subfunctions of try_to_unmap: try_to_unmap_one called
Wanlong Gao99ef0312011-10-31 17:08:51 -07001192 * repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001193 */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001194int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1195 unsigned long address, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001196{
1197 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001198 pte_t *pte;
1199 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001200 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001201 int ret = SWAP_AGAIN;
1202
Nick Piggin479db0b2008-08-20 14:09:18 -07001203 pte = page_check_address(page, mm, address, &ptl, 0);
Hugh Dickinsc0718802005-10-29 18:16:31 -07001204 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -07001205 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001206
1207 /*
1208 * If the page is mlock()d, we cannot swap it out.
1209 * If it's recently referenced (perhaps page_referenced
1210 * skipped over this mm) then we should reactivate it.
1211 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001212 if (!(flags & TTU_IGNORE_MLOCK)) {
KOSAKI Motohirocaed0f482009-12-14 17:59:45 -08001213 if (vma->vm_flags & VM_LOCKED)
1214 goto out_mlock;
1215
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001216 if (TTU_ACTION(flags) == TTU_MUNLOCK)
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001217 goto out_unmap;
Andi Kleen14fa31b2009-09-16 11:50:10 +02001218 }
1219 if (!(flags & TTU_IGNORE_ACCESS)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001220 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1221 ret = SWAP_FAIL;
1222 goto out_unmap;
1223 }
1224 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001225
Linus Torvalds1da177e2005-04-16 15:20:36 -07001226 /* Nuke the page table entry. */
1227 flush_cache_page(vma, address, page_to_pfn(page));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001228 pteval = ptep_clear_flush(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229
1230 /* Move the dirty bit to the physical page now the pte is gone. */
1231 if (pte_dirty(pteval))
1232 set_page_dirty(page);
1233
Hugh Dickins365e9c872005-10-29 18:16:18 -07001234 /* Update high watermark before we lower rss */
1235 update_hiwater_rss(mm);
1236
Andi Kleen888b9f72009-09-16 11:50:11 +02001237 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
1238 if (PageAnon(page))
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001239 dec_mm_counter(mm, MM_ANONPAGES);
Andi Kleen888b9f72009-09-16 11:50:11 +02001240 else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001241 dec_mm_counter(mm, MM_FILEPAGES);
Andi Kleen888b9f72009-09-16 11:50:11 +02001242 set_pte_at(mm, address, pte,
1243 swp_entry_to_pte(make_hwpoison_entry(page)));
1244 } else if (PageAnon(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001245 swp_entry_t entry = { .val = page_private(page) };
Christoph Lameter06972122006-06-23 02:03:35 -07001246
1247 if (PageSwapCache(page)) {
1248 /*
1249 * Store the swap location in the pte.
1250 * See handle_pte_fault() ...
1251 */
Hugh Dickins570a335b2009-12-14 17:58:46 -08001252 if (swap_duplicate(entry) < 0) {
1253 set_pte_at(mm, address, pte, pteval);
1254 ret = SWAP_FAIL;
1255 goto out_unmap;
1256 }
Christoph Lameter06972122006-06-23 02:03:35 -07001257 if (list_empty(&mm->mmlist)) {
1258 spin_lock(&mmlist_lock);
1259 if (list_empty(&mm->mmlist))
1260 list_add(&mm->mmlist, &init_mm.mmlist);
1261 spin_unlock(&mmlist_lock);
1262 }
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001263 dec_mm_counter(mm, MM_ANONPAGES);
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -08001264 inc_mm_counter(mm, MM_SWAPENTS);
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001265 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
Christoph Lameter06972122006-06-23 02:03:35 -07001266 /*
1267 * Store the pfn of the page in a special migration
1268 * pte. do_swap_page() will wait until the migration
1269 * pte is removed and then restart fault handling.
1270 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001271 BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION);
Christoph Lameter06972122006-06-23 02:03:35 -07001272 entry = make_migration_entry(page, pte_write(pteval));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001273 }
1274 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1275 BUG_ON(pte_file(*pte));
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001276 } else if (IS_ENABLED(CONFIG_MIGRATION) &&
1277 (TTU_ACTION(flags) == TTU_MIGRATION)) {
Christoph Lameter04e62a22006-06-23 02:03:38 -07001278 /* Establish migration entry for a file page */
1279 swp_entry_t entry;
1280 entry = make_migration_entry(page, pte_write(pteval));
1281 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1282 } else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001283 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001284
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001285 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286 page_cache_release(page);
1287
1288out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -07001289 pte_unmap_unlock(pte, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001290 if (ret != SWAP_FAIL)
1291 mmu_notifier_invalidate_page(mm, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001292out:
1293 return ret;
KOSAKI Motohirocaed0f482009-12-14 17:59:45 -08001294
1295out_mlock:
1296 pte_unmap_unlock(pte, ptl);
1297
1298
1299 /*
1300 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
1301 * unstable result and race. Plus, We can't wait here because
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001302 * we now hold anon_vma->mutex or mapping->i_mmap_mutex.
KOSAKI Motohirocaed0f482009-12-14 17:59:45 -08001303 * if trylock failed, the page remain in evictable lru and later
1304 * vmscan could retry to move the page to unevictable lru if the
1305 * page is actually mlocked.
1306 */
1307 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
1308 if (vma->vm_flags & VM_LOCKED) {
1309 mlock_vma_page(page);
1310 ret = SWAP_MLOCK;
1311 }
1312 up_read(&vma->vm_mm->mmap_sem);
1313 }
1314 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315}
1316
1317/*
1318 * objrmap doesn't work for nonlinear VMAs because the assumption that
1319 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
1320 * Consequently, given a particular page and its ->index, we cannot locate the
1321 * ptes which are mapping that page without an exhaustive linear search.
1322 *
1323 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
1324 * maps the file to which the target page belongs. The ->vm_private_data field
1325 * holds the current cursor into that scan. Successive searches will circulate
1326 * around the vma's virtual address space.
1327 *
1328 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
1329 * more scanning pressure is placed against them as well. Eventually pages
1330 * will become fully unmapped and are eligible for eviction.
1331 *
1332 * For very sparsely populated VMAs this is a little inefficient - chances are
1333 * there there won't be many ptes located within the scan cluster. In this case
1334 * maybe we could scan further - to the end of the pte page, perhaps.
Nick Pigginb291f002008-10-18 20:26:44 -07001335 *
1336 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
1337 * acquire it without blocking. If vma locked, mlock the pages in the cluster,
1338 * rather than unmapping them. If we encounter the "check_page" that vmscan is
1339 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340 */
1341#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
1342#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
1343
Nick Pigginb291f002008-10-18 20:26:44 -07001344static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
1345 struct vm_area_struct *vma, struct page *check_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346{
1347 struct mm_struct *mm = vma->vm_mm;
1348 pgd_t *pgd;
1349 pud_t *pud;
1350 pmd_t *pmd;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001351 pte_t *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001352 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001353 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 struct page *page;
1355 unsigned long address;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001356 unsigned long mmun_start; /* For mmu_notifiers */
1357 unsigned long mmun_end; /* For mmu_notifiers */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001358 unsigned long end;
Nick Pigginb291f002008-10-18 20:26:44 -07001359 int ret = SWAP_AGAIN;
1360 int locked_vma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001361
Linus Torvalds1da177e2005-04-16 15:20:36 -07001362 address = (vma->vm_start + cursor) & CLUSTER_MASK;
1363 end = address + CLUSTER_SIZE;
1364 if (address < vma->vm_start)
1365 address = vma->vm_start;
1366 if (end > vma->vm_end)
1367 end = vma->vm_end;
1368
1369 pgd = pgd_offset(mm, address);
1370 if (!pgd_present(*pgd))
Nick Pigginb291f002008-10-18 20:26:44 -07001371 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001372
1373 pud = pud_offset(pgd, address);
1374 if (!pud_present(*pud))
Nick Pigginb291f002008-10-18 20:26:44 -07001375 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001376
1377 pmd = pmd_offset(pud, address);
1378 if (!pmd_present(*pmd))
Nick Pigginb291f002008-10-18 20:26:44 -07001379 return ret;
1380
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001381 mmun_start = address;
1382 mmun_end = end;
1383 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1384
Nick Pigginb291f002008-10-18 20:26:44 -07001385 /*
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001386 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
Nick Pigginb291f002008-10-18 20:26:44 -07001387 * keep the sem while scanning the cluster for mlocking pages.
1388 */
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001389 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001390 locked_vma = (vma->vm_flags & VM_LOCKED);
1391 if (!locked_vma)
1392 up_read(&vma->vm_mm->mmap_sem); /* don't need it */
1393 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001394
1395 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001396
Hugh Dickins365e9c872005-10-29 18:16:18 -07001397 /* Update high watermark before we lower rss */
1398 update_hiwater_rss(mm);
1399
Hugh Dickinsc0718802005-10-29 18:16:31 -07001400 for (; address < end; pte++, address += PAGE_SIZE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001401 if (!pte_present(*pte))
1402 continue;
Linus Torvalds6aab3412005-11-28 14:34:23 -08001403 page = vm_normal_page(vma, address, *pte);
1404 BUG_ON(!page || PageAnon(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001405
Nick Pigginb291f002008-10-18 20:26:44 -07001406 if (locked_vma) {
1407 mlock_vma_page(page); /* no-op if already mlocked */
1408 if (page == check_page)
1409 ret = SWAP_MLOCK;
1410 continue; /* don't unmap */
1411 }
1412
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001413 if (ptep_clear_flush_young_notify(vma, address, pte))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001414 continue;
1415
1416 /* Nuke the page table entry. */
Ben Collinseca35132005-11-29 11:45:26 -08001417 flush_cache_page(vma, address, pte_pfn(*pte));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001418 pteval = ptep_clear_flush(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419
1420 /* If nonlinear, store the file page offset in the pte. */
1421 if (page->index != linear_page_index(vma, address))
1422 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
1423
1424 /* Move the dirty bit to the physical page now the pte is gone. */
1425 if (pte_dirty(pteval))
1426 set_page_dirty(page);
1427
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001428 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429 page_cache_release(page);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001430 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001431 (*mapcount)--;
1432 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001433 pte_unmap_unlock(pte - 1, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001434 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Nick Pigginb291f002008-10-18 20:26:44 -07001435 if (locked_vma)
1436 up_read(&vma->vm_mm->mmap_sem);
1437 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438}
1439
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001440bool is_vma_temporary_stack(struct vm_area_struct *vma)
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001441{
1442 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1443
1444 if (!maybe_stack)
1445 return false;
1446
1447 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1448 VM_STACK_INCOMPLETE_SETUP)
1449 return true;
1450
1451 return false;
1452}
1453
Nick Pigginb291f002008-10-18 20:26:44 -07001454/**
1455 * try_to_unmap_anon - unmap or unlock anonymous page using the object-based
1456 * rmap method
1457 * @page: the page to unmap/unlock
Huang Shijie8051be52009-12-14 17:58:50 -08001458 * @flags: action and flags
Nick Pigginb291f002008-10-18 20:26:44 -07001459 *
1460 * Find all the mappings of a page using the mapping pointer and the vma chains
1461 * contained in the anon_vma struct it points to.
1462 *
1463 * This function is only called from try_to_unmap/try_to_munlock for
1464 * anonymous pages.
1465 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1466 * where the page was found will be held for write. So, we won't recheck
1467 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1468 * 'LOCKED.
1469 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001470static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001471{
1472 struct anon_vma *anon_vma;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001473 pgoff_t pgoff;
Rik van Riel5beb4932010-03-05 13:42:07 -08001474 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001475 int ret = SWAP_AGAIN;
Nick Pigginb291f002008-10-18 20:26:44 -07001476
Linus Torvalds1da177e2005-04-16 15:20:36 -07001477 anon_vma = page_lock_anon_vma(page);
1478 if (!anon_vma)
1479 return ret;
1480
Michel Lespinassebf181b92012-10-08 16:31:39 -07001481 pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1482 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -08001483 struct vm_area_struct *vma = avc->vma;
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001484 unsigned long address;
1485
1486 /*
1487 * During exec, a temporary VMA is setup and later moved.
1488 * The VMA is moved under the anon_vma lock but not the
1489 * page tables leading to a race where migration cannot
1490 * find the migration ptes. Rather than increasing the
1491 * locking requirements of exec(), migration skips
1492 * temporary VMAs until after exec() completes.
1493 */
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001494 if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) &&
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001495 is_vma_temporary_stack(vma))
1496 continue;
1497
1498 address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -08001499 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001500 if (ret != SWAP_AGAIN || !page_mapped(page))
1501 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -08001503
1504 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001505 return ret;
1506}
1507
1508/**
Nick Pigginb291f002008-10-18 20:26:44 -07001509 * try_to_unmap_file - unmap/unlock file page using the object-based rmap method
1510 * @page: the page to unmap/unlock
Andi Kleen14fa31b2009-09-16 11:50:10 +02001511 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512 *
1513 * Find all the mappings of a page using the mapping pointer and the vma chains
1514 * contained in the address_space struct it points to.
1515 *
Nick Pigginb291f002008-10-18 20:26:44 -07001516 * This function is only called from try_to_unmap/try_to_munlock for
1517 * object-based pages.
1518 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1519 * where the page was found will be held for write. So, we won't recheck
1520 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1521 * 'LOCKED.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001522 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001523static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524{
1525 struct address_space *mapping = page->mapping;
1526 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1527 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001528 int ret = SWAP_AGAIN;
1529 unsigned long cursor;
1530 unsigned long max_nl_cursor = 0;
1531 unsigned long max_nl_size = 0;
1532 unsigned int mapcount;
1533
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001534 mutex_lock(&mapping->i_mmap_mutex);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001535 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -08001536 unsigned long address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -08001537 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001538 if (ret != SWAP_AGAIN || !page_mapped(page))
1539 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001540 }
1541
1542 if (list_empty(&mapping->i_mmap_nonlinear))
1543 goto out;
1544
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001545 /*
1546 * We don't bother to try to find the munlocked page in nonlinears.
1547 * It's costly. Instead, later, page reclaim logic may call
1548 * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily.
1549 */
1550 if (TTU_ACTION(flags) == TTU_MUNLOCK)
1551 goto out;
1552
Linus Torvalds1da177e2005-04-16 15:20:36 -07001553 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001554 shared.nonlinear) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 cursor = (unsigned long) vma->vm_private_data;
1556 if (cursor > max_nl_cursor)
1557 max_nl_cursor = cursor;
1558 cursor = vma->vm_end - vma->vm_start;
1559 if (cursor > max_nl_size)
1560 max_nl_size = cursor;
1561 }
1562
Nick Pigginb291f002008-10-18 20:26:44 -07001563 if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001564 ret = SWAP_FAIL;
1565 goto out;
1566 }
1567
1568 /*
1569 * We don't try to search for this page in the nonlinear vmas,
1570 * and page_referenced wouldn't have found it anyway. Instead
1571 * just walk the nonlinear vmas trying to age and unmap some.
1572 * The mapcount of the page we came in with is irrelevant,
1573 * but even so use it as a guide to how hard we should try?
1574 */
1575 mapcount = page_mapcount(page);
1576 if (!mapcount)
1577 goto out;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001578 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001579
1580 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
1581 if (max_nl_cursor == 0)
1582 max_nl_cursor = CLUSTER_SIZE;
1583
1584 do {
1585 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001586 shared.nonlinear) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001587 cursor = (unsigned long) vma->vm_private_data;
Hugh Dickins839b9682005-09-03 15:54:43 -07001588 while ( cursor < max_nl_cursor &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 cursor < vma->vm_end - vma->vm_start) {
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001590 if (try_to_unmap_cluster(cursor, &mapcount,
1591 vma, page) == SWAP_MLOCK)
1592 ret = SWAP_MLOCK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001593 cursor += CLUSTER_SIZE;
1594 vma->vm_private_data = (void *) cursor;
1595 if ((int)mapcount <= 0)
1596 goto out;
1597 }
1598 vma->vm_private_data = (void *) max_nl_cursor;
1599 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001600 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001601 max_nl_cursor += CLUSTER_SIZE;
1602 } while (max_nl_cursor <= max_nl_size);
1603
1604 /*
1605 * Don't loop forever (perhaps all the remaining pages are
1606 * in locked vmas). Reset cursor on all unreserved nonlinear
1607 * vmas, now forgetting on which ones it had fallen behind.
1608 */
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001609 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear)
Hugh Dickins101d2be2005-11-21 21:32:16 -08001610 vma->vm_private_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611out:
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001612 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001613 return ret;
1614}
1615
1616/**
1617 * try_to_unmap - try to remove all page table mappings to a page
1618 * @page: the page to get unmapped
Andi Kleen14fa31b2009-09-16 11:50:10 +02001619 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620 *
1621 * Tries to remove all the page table entries which are mapping this
1622 * page, used in the pageout path. Caller must hold the page lock.
1623 * Return values are:
1624 *
1625 * SWAP_SUCCESS - we succeeded in removing all mappings
1626 * SWAP_AGAIN - we missed a mapping, try again later
1627 * SWAP_FAIL - the page is unswappable
Nick Pigginb291f002008-10-18 20:26:44 -07001628 * SWAP_MLOCK - page is mlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001630int try_to_unmap(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001631{
1632 int ret;
1633
Linus Torvalds1da177e2005-04-16 15:20:36 -07001634 BUG_ON(!PageLocked(page));
Andrea Arcangeli91600e92011-01-13 15:47:16 -08001635 VM_BUG_ON(!PageHuge(page) && PageTransHuge(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636
Hugh Dickins5ad64682009-12-14 17:59:24 -08001637 if (unlikely(PageKsm(page)))
1638 ret = try_to_unmap_ksm(page, flags);
1639 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001640 ret = try_to_unmap_anon(page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001641 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001642 ret = try_to_unmap_file(page, flags);
Nick Pigginb291f002008-10-18 20:26:44 -07001643 if (ret != SWAP_MLOCK && !page_mapped(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001644 ret = SWAP_SUCCESS;
1645 return ret;
1646}
Nikita Danilov81b40822005-05-01 08:58:36 -07001647
Nick Pigginb291f002008-10-18 20:26:44 -07001648/**
1649 * try_to_munlock - try to munlock a page
1650 * @page: the page to be munlocked
1651 *
1652 * Called from munlock code. Checks all of the VMAs mapping the page
1653 * to make sure nobody else has this page mlocked. The page will be
1654 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1655 *
1656 * Return values are:
1657 *
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001658 * SWAP_AGAIN - no vma is holding page mlocked, or,
Nick Pigginb291f002008-10-18 20:26:44 -07001659 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
Hugh Dickins5ad64682009-12-14 17:59:24 -08001660 * SWAP_FAIL - page cannot be located at present
Nick Pigginb291f002008-10-18 20:26:44 -07001661 * SWAP_MLOCK - page is now mlocked.
1662 */
1663int try_to_munlock(struct page *page)
1664{
1665 VM_BUG_ON(!PageLocked(page) || PageLRU(page));
1666
Hugh Dickins5ad64682009-12-14 17:59:24 -08001667 if (unlikely(PageKsm(page)))
1668 return try_to_unmap_ksm(page, TTU_MUNLOCK);
1669 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001670 return try_to_unmap_anon(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001671 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001672 return try_to_unmap_file(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001673}
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001674
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001675void __put_anon_vma(struct anon_vma *anon_vma)
Rik van Riel76545062010-08-09 17:18:41 -07001676{
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001677 struct anon_vma *root = anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -07001678
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001679 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1680 anon_vma_free(root);
Rik van Riel76545062010-08-09 17:18:41 -07001681
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001682 anon_vma_free(anon_vma);
Rik van Riel76545062010-08-09 17:18:41 -07001683}
Rik van Riel76545062010-08-09 17:18:41 -07001684
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001685#ifdef CONFIG_MIGRATION
1686/*
1687 * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
1688 * Called by migrate.c to remove migration ptes, but might be used more later.
1689 */
1690static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
1691 struct vm_area_struct *, unsigned long, void *), void *arg)
1692{
1693 struct anon_vma *anon_vma;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001694 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
Rik van Riel5beb4932010-03-05 13:42:07 -08001695 struct anon_vma_chain *avc;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001696 int ret = SWAP_AGAIN;
1697
1698 /*
1699 * Note: remove_migration_ptes() cannot use page_lock_anon_vma()
1700 * because that depends on page_mapped(); but not all its usages
Mel Gorman3f6c8272010-05-24 14:32:17 -07001701 * are holding mmap_sem. Users without mmap_sem are required to
1702 * take a reference count to prevent the anon_vma disappearing
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001703 */
1704 anon_vma = page_anon_vma(page);
1705 if (!anon_vma)
1706 return ret;
Rik van Rielcba48b92010-08-09 17:18:38 -07001707 anon_vma_lock(anon_vma);
Michel Lespinassebf181b92012-10-08 16:31:39 -07001708 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -08001709 struct vm_area_struct *vma = avc->vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001710 unsigned long address = vma_address(page, vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001711 ret = rmap_one(page, vma, address, arg);
1712 if (ret != SWAP_AGAIN)
1713 break;
1714 }
Rik van Rielcba48b92010-08-09 17:18:38 -07001715 anon_vma_unlock(anon_vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001716 return ret;
1717}
1718
1719static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *,
1720 struct vm_area_struct *, unsigned long, void *), void *arg)
1721{
1722 struct address_space *mapping = page->mapping;
1723 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1724 struct vm_area_struct *vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001725 int ret = SWAP_AGAIN;
1726
1727 if (!mapping)
1728 return ret;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001729 mutex_lock(&mapping->i_mmap_mutex);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001730 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001731 unsigned long address = vma_address(page, vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001732 ret = rmap_one(page, vma, address, arg);
1733 if (ret != SWAP_AGAIN)
1734 break;
1735 }
1736 /*
1737 * No nonlinear handling: being always shared, nonlinear vmas
1738 * never contain migration ptes. Decide what to do about this
1739 * limitation to linear when we need rmap_walk() on nonlinear.
1740 */
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001741 mutex_unlock(&mapping->i_mmap_mutex);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001742 return ret;
1743}
1744
1745int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
1746 struct vm_area_struct *, unsigned long, void *), void *arg)
1747{
1748 VM_BUG_ON(!PageLocked(page));
1749
1750 if (unlikely(PageKsm(page)))
1751 return rmap_walk_ksm(page, rmap_one, arg);
1752 else if (PageAnon(page))
1753 return rmap_walk_anon(page, rmap_one, arg);
1754 else
1755 return rmap_walk_file(page, rmap_one, arg);
1756}
1757#endif /* CONFIG_MIGRATION */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001758
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001759#ifdef CONFIG_HUGETLB_PAGE
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001760/*
1761 * The following three functions are for anonymous (private mapped) hugepages.
1762 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1763 * and no lru code, because we handle hugepages differently from common pages.
1764 */
1765static void __hugepage_set_anon_rmap(struct page *page,
1766 struct vm_area_struct *vma, unsigned long address, int exclusive)
1767{
1768 struct anon_vma *anon_vma = vma->anon_vma;
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001769
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001770 BUG_ON(!anon_vma);
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001771
1772 if (PageAnon(page))
1773 return;
1774 if (!exclusive)
1775 anon_vma = anon_vma->root;
1776
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001777 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1778 page->mapping = (struct address_space *) anon_vma;
1779 page->index = linear_page_index(vma, address);
1780}
1781
1782void hugepage_add_anon_rmap(struct page *page,
1783 struct vm_area_struct *vma, unsigned long address)
1784{
1785 struct anon_vma *anon_vma = vma->anon_vma;
1786 int first;
Naoya Horiguchia850ea32010-09-10 13:23:06 +09001787
1788 BUG_ON(!PageLocked(page));
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001789 BUG_ON(!anon_vma);
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001790 /* address might be in next vma when migration races vma_adjust */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001791 first = atomic_inc_and_test(&page->_mapcount);
1792 if (first)
1793 __hugepage_set_anon_rmap(page, vma, address, 0);
1794}
1795
1796void hugepage_add_new_anon_rmap(struct page *page,
1797 struct vm_area_struct *vma, unsigned long address)
1798{
1799 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1800 atomic_set(&page->_mapcount, 0);
1801 __hugepage_set_anon_rmap(page, vma, address, 1);
1802}
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001803#endif /* CONFIG_HUGETLB_PAGE */