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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
Ingo Molnar5a505082012-12-02 19:56:46 +000027 * anon_vma->rwsem
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 *
Ingo Molnar5a505082012-12-02 19:56:46 +000040 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
Peter Zijlstra9b679322011-06-27 16:18:09 -070041 * ->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 /*
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +000090 * Synchronize against page_lock_anon_vma_read() such that
Peter Zijlstra88c22082011-05-24 17:12:13 -070091 * 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
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +000096 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
Peter Zijlstra88c22082011-05-24 17:12:13 -070097 *
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +000098 * page_lock_anon_vma_read() VS put_anon_vma()
99 * down_read_trylock() atomic_dec_and_test()
Peter Zijlstra88c22082011-05-24 17:12:13 -0700100 * LOCK MB
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000101 * atomic_read() rwsem_is_locked()
Peter Zijlstra88c22082011-05-24 17:12:13 -0700102 *
103 * LOCK should suffice since the actual taking of the lock must
104 * happen _before_ what follows.
105 */
Ingo Molnar5a505082012-12-02 19:56:46 +0000106 if (rwsem_is_locked(&anon_vma->root->rwsem)) {
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000107 anon_vma_lock_write(anon_vma);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -0800108 anon_vma_unlock_write(anon_vma);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700109 }
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
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000149 * optimistically looked up an anon_vma in page_lock_anon_vma_read()
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700150 * 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
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000184 anon_vma_lock_write(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);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -0800194 anon_vma_unlock_write(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))
Ingo Molnar5a505082012-12-02 19:56:46 +0000222 up_write(&root->rwsem);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700223 root = new_root;
Ingo Molnar5a505082012-12-02 19:56:46 +0000224 down_write(&root->rwsem);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700225 }
226 return root;
227}
228
229static inline void unlock_anon_vma_root(struct anon_vma *root)
230{
231 if (root)
Ingo Molnar5a505082012-12-02 19:56:46 +0000232 up_write(&root->rwsem);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700233}
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;
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000309 anon_vma_lock_write(anon_vma);
Rik van Riel5c341ee12010-08-09 17:18:39 -0700310 anon_vma_chain_link(vma, avc, anon_vma);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -0800311 anon_vma_unlock_write(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()
Ingo Molnar5a505082012-12-02 19:56:46 +0000352 * needing to write-acquire the anon_vma->root->rwsem.
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200353 */
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
Ingo Molnar5a505082012-12-02 19:56:46 +0000368 init_rwsem(&anon_vma->rwsem);
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 */
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000445struct anon_vma *page_lock_anon_vma_read(struct page *page)
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700446{
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);
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000460 if (down_read_trylock(&root_anon_vma->rwsem)) {
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)) {
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000467 up_read(&root_anon_vma->rwsem);
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();
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000487 anon_vma_lock_read(anon_vma);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700488
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
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000493 * we'll deadlock on the anon_vma_lock_write() recursion.
Peter Zijlstra88c22082011-05-24 17:12:13 -0700494 */
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000495 anon_vma_unlock_read(anon_vma);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700496 __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
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000507void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800508{
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000509 anon_vma_unlock_read(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
Bob Liu62190492012-12-11 16:00:37 -0800565pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
566{
567 pgd_t *pgd;
568 pud_t *pud;
569 pmd_t *pmd = NULL;
570
571 pgd = pgd_offset(mm, address);
572 if (!pgd_present(*pgd))
573 goto out;
574
575 pud = pud_offset(pgd, address);
576 if (!pud_present(*pud))
577 goto out;
578
579 pmd = pmd_offset(pud, address);
580 if (!pmd_present(*pmd))
581 pmd = NULL;
582out:
583 return pmd;
584}
585
Linus Torvalds1da177e2005-04-16 15:20:36 -0700586/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700587 * Check that @page is mapped at @address into @mm.
588 *
Nick Piggin479db0b2008-08-20 14:09:18 -0700589 * If @sync is false, page_check_address may perform a racy check to avoid
590 * the page table lock when the pte is not present (helpful when reclaiming
591 * highly shared pages).
592 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700593 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700594 */
Namhyung Kime9a81a82010-10-26 14:22:01 -0700595pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
Nick Piggin479db0b2008-08-20 14:09:18 -0700596 unsigned long address, spinlock_t **ptlp, int sync)
Nikita Danilov81b40822005-05-01 08:58:36 -0700597{
Nikita Danilov81b40822005-05-01 08:58:36 -0700598 pmd_t *pmd;
599 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700600 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700601
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900602 if (unlikely(PageHuge(page))) {
603 pte = huge_pte_offset(mm, address);
604 ptl = &mm->page_table_lock;
605 goto check;
606 }
607
Bob Liu62190492012-12-11 16:00:37 -0800608 pmd = mm_find_pmd(mm, address);
609 if (!pmd)
Hugh Dickinsc0718802005-10-29 18:16:31 -0700610 return NULL;
611
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800612 if (pmd_trans_huge(*pmd))
613 return NULL;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700614
615 pte = pte_offset_map(pmd, address);
616 /* Make a quick check before getting the lock */
Nick Piggin479db0b2008-08-20 14:09:18 -0700617 if (!sync && !pte_present(*pte)) {
Hugh Dickinsc0718802005-10-29 18:16:31 -0700618 pte_unmap(pte);
619 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700620 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700621
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700622 ptl = pte_lockptr(mm, pmd);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900623check:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700624 spin_lock(ptl);
625 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
626 *ptlp = ptl;
627 return pte;
628 }
629 pte_unmap_unlock(pte, ptl);
630 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700631}
632
Nick Pigginb291f002008-10-18 20:26:44 -0700633/**
634 * page_mapped_in_vma - check whether a page is really mapped in a VMA
635 * @page: the page to test
636 * @vma: the VMA to test
637 *
638 * Returns 1 if the page is mapped into the page tables of the VMA, 0
639 * if the page is not mapped into the page tables of this VMA. Only
640 * valid for normal file or anonymous VMAs.
641 */
Andi Kleen6a460792009-09-16 11:50:15 +0200642int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
Nick Pigginb291f002008-10-18 20:26:44 -0700643{
644 unsigned long address;
645 pte_t *pte;
646 spinlock_t *ptl;
647
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700648 address = __vma_address(page, vma);
649 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
Nick Pigginb291f002008-10-18 20:26:44 -0700650 return 0;
651 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
652 if (!pte) /* the page is not in this mm */
653 return 0;
654 pte_unmap_unlock(pte, ptl);
655
656 return 1;
657}
658
Nikita Danilov81b40822005-05-01 08:58:36 -0700659/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700660 * Subfunctions of page_referenced: page_referenced_one called
661 * repeatedly from either page_referenced_anon or page_referenced_file.
662 */
Hugh Dickins5ad64682009-12-14 17:59:24 -0800663int page_referenced_one(struct page *page, struct vm_area_struct *vma,
664 unsigned long address, unsigned int *mapcount,
665 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700666{
667 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700668 int referenced = 0;
669
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800670 if (unlikely(PageTransHuge(page))) {
671 pmd_t *pmd;
672
673 spin_lock(&mm->page_table_lock);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800674 /*
675 * rmap might return false positives; we must filter
676 * these out using page_check_address_pmd().
677 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800678 pmd = page_check_address_pmd(page, mm, address,
679 PAGE_CHECK_ADDRESS_PMD_FLAG);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800680 if (!pmd) {
681 spin_unlock(&mm->page_table_lock);
682 goto out;
683 }
684
685 if (vma->vm_flags & VM_LOCKED) {
686 spin_unlock(&mm->page_table_lock);
687 *mapcount = 0; /* break early from loop */
688 *vm_flags |= VM_LOCKED;
689 goto out;
690 }
691
692 /* go ahead even if the pmd is pmd_trans_splitting() */
693 if (pmdp_clear_flush_young_notify(vma, address, pmd))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800694 referenced++;
695 spin_unlock(&mm->page_table_lock);
696 } else {
697 pte_t *pte;
698 spinlock_t *ptl;
699
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800700 /*
701 * rmap might return false positives; we must filter
702 * these out using page_check_address().
703 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800704 pte = page_check_address(page, mm, address, &ptl, 0);
705 if (!pte)
706 goto out;
707
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800708 if (vma->vm_flags & VM_LOCKED) {
709 pte_unmap_unlock(pte, ptl);
710 *mapcount = 0; /* break early from loop */
711 *vm_flags |= VM_LOCKED;
712 goto out;
713 }
714
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800715 if (ptep_clear_flush_young_notify(vma, address, pte)) {
716 /*
717 * Don't treat a reference through a sequentially read
718 * mapping as such. If the page has been used in
719 * another mapping, we will catch it; if this other
720 * mapping is already gone, the unmap path will have
721 * set PG_referenced or activated the page.
722 */
Joe Perches64363aa2013-07-08 16:00:18 -0700723 if (likely(!(vma->vm_flags & VM_SEQ_READ)))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800724 referenced++;
725 }
726 pte_unmap_unlock(pte, ptl);
727 }
728
Hugh Dickinsc0718802005-10-29 18:16:31 -0700729 (*mapcount)--;
Huang Shijie273f0472009-12-14 17:58:51 -0800730
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700731 if (referenced)
732 *vm_flags |= vma->vm_flags;
Huang Shijie273f0472009-12-14 17:58:51 -0800733out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700734 return referenced;
735}
736
Balbir Singhbed71612008-02-07 00:14:01 -0800737static int page_referenced_anon(struct page *page,
Johannes Weiner72835c82012-01-12 17:18:32 -0800738 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700739 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700740{
741 unsigned int mapcount;
742 struct anon_vma *anon_vma;
Michel Lespinassebf181b92012-10-08 16:31:39 -0700743 pgoff_t pgoff;
Rik van Riel5beb4932010-03-05 13:42:07 -0800744 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700745 int referenced = 0;
746
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000747 anon_vma = page_lock_anon_vma_read(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700748 if (!anon_vma)
749 return referenced;
750
751 mapcount = page_mapcount(page);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700752 pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
753 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -0800754 struct vm_area_struct *vma = avc->vma;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800755 unsigned long address = vma_address(page, vma);
Balbir Singhbed71612008-02-07 00:14:01 -0800756 /*
757 * If we are reclaiming on behalf of a cgroup, skip
758 * counting on behalf of references from different
759 * cgroups
760 */
Johannes Weiner72835c82012-01-12 17:18:32 -0800761 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
Balbir Singhbed71612008-02-07 00:14:01 -0800762 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800763 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700764 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700765 if (!mapcount)
766 break;
767 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800768
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000769 page_unlock_anon_vma_read(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770 return referenced;
771}
772
773/**
774 * page_referenced_file - referenced check for object-based rmap
775 * @page: the page we're checking references on.
Johannes Weiner72835c82012-01-12 17:18:32 -0800776 * @memcg: target memory control group
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700777 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700778 *
779 * For an object-based mapped page, find all the places it is mapped and
780 * check/clear the referenced flag. This is done by following the page->mapping
781 * pointer, then walking the chain of vmas it holds. It returns the number
782 * of references it found.
783 *
784 * This function is only called from page_referenced for object-based pages.
785 */
Balbir Singhbed71612008-02-07 00:14:01 -0800786static int page_referenced_file(struct page *page,
Johannes Weiner72835c82012-01-12 17:18:32 -0800787 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700788 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700789{
790 unsigned int mapcount;
791 struct address_space *mapping = page->mapping;
792 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
793 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 int referenced = 0;
795
796 /*
797 * The caller's checks on page->mapping and !PageAnon have made
798 * sure that this is a file page: the check for page->mapping
799 * excludes the case just before it gets set on an anon page.
800 */
801 BUG_ON(PageAnon(page));
802
803 /*
804 * The page lock not only makes sure that page->mapping cannot
805 * suddenly be NULLified by truncation, it makes sure that the
806 * structure at mapping cannot be freed and reused yet,
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700807 * so we can safely take mapping->i_mmap_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700808 */
809 BUG_ON(!PageLocked(page));
810
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700811 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700812
813 /*
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700814 * i_mmap_mutex does not stabilize mapcount at all, but mapcount
Linus Torvalds1da177e2005-04-16 15:20:36 -0700815 * is more likely to be accurate if we note it after spinning.
816 */
817 mapcount = page_mapcount(page);
818
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -0700819 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800820 unsigned long address = vma_address(page, vma);
Balbir Singhbed71612008-02-07 00:14:01 -0800821 /*
822 * If we are reclaiming on behalf of a cgroup, skip
823 * counting on behalf of references from different
824 * cgroups
825 */
Johannes Weiner72835c82012-01-12 17:18:32 -0800826 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
Balbir Singhbed71612008-02-07 00:14:01 -0800827 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800828 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700829 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700830 if (!mapcount)
831 break;
832 }
833
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700834 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835 return referenced;
836}
837
838/**
839 * page_referenced - test if the page was referenced
840 * @page: the page to test
841 * @is_locked: caller holds lock on the page
Johannes Weiner72835c82012-01-12 17:18:32 -0800842 * @memcg: target memory cgroup
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700843 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700844 *
845 * Quick test_and_clear_referenced for all mappings to a page,
846 * returns the number of ptes which referenced the page.
847 */
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700848int page_referenced(struct page *page,
849 int is_locked,
Johannes Weiner72835c82012-01-12 17:18:32 -0800850 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700851 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700852{
853 int referenced = 0;
Hugh Dickins5ad64682009-12-14 17:59:24 -0800854 int we_locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700855
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700856 *vm_flags = 0;
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800857 if (page_mapped(page) && page_rmapping(page)) {
Hugh Dickins5ad64682009-12-14 17:59:24 -0800858 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
859 we_locked = trylock_page(page);
860 if (!we_locked) {
861 referenced++;
862 goto out;
863 }
864 }
865 if (unlikely(PageKsm(page)))
Johannes Weiner72835c82012-01-12 17:18:32 -0800866 referenced += page_referenced_ksm(page, memcg,
Hugh Dickins5ad64682009-12-14 17:59:24 -0800867 vm_flags);
868 else if (PageAnon(page))
Johannes Weiner72835c82012-01-12 17:18:32 -0800869 referenced += page_referenced_anon(page, memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700870 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800871 else if (page->mapping)
Johannes Weiner72835c82012-01-12 17:18:32 -0800872 referenced += page_referenced_file(page, memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700873 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800874 if (we_locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700875 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 }
Hugh Dickins5ad64682009-12-14 17:59:24 -0800877out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700878 return referenced;
879}
880
Hugh Dickins1cb17292009-12-14 17:59:01 -0800881static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
882 unsigned long address)
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700883{
884 struct mm_struct *mm = vma->vm_mm;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100885 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700886 spinlock_t *ptl;
887 int ret = 0;
888
Nick Piggin479db0b2008-08-20 14:09:18 -0700889 pte = page_check_address(page, mm, address, &ptl, 1);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700890 if (!pte)
891 goto out;
892
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100893 if (pte_dirty(*pte) || pte_write(*pte)) {
894 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700895
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100896 flush_cache_page(vma, address, pte_pfn(*pte));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700897 entry = ptep_clear_flush(vma, address, pte);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100898 entry = pte_wrprotect(entry);
899 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -0800900 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100901 ret = 1;
902 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700903
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700904 pte_unmap_unlock(pte, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -0700905
906 if (ret)
907 mmu_notifier_invalidate_page(mm, address);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700908out:
909 return ret;
910}
911
912static int page_mkclean_file(struct address_space *mapping, struct page *page)
913{
914 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
915 struct vm_area_struct *vma;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700916 int ret = 0;
917
918 BUG_ON(PageAnon(page));
919
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700920 mutex_lock(&mapping->i_mmap_mutex);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -0700921 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800922 if (vma->vm_flags & VM_SHARED) {
923 unsigned long address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -0800924 ret += page_mkclean_one(page, vma, address);
925 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700926 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700927 mutex_unlock(&mapping->i_mmap_mutex);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700928 return ret;
929}
930
931int page_mkclean(struct page *page)
932{
933 int ret = 0;
934
935 BUG_ON(!PageLocked(page));
936
937 if (page_mapped(page)) {
938 struct address_space *mapping = page_mapping(page);
Jan Karaef5d4372012-10-25 13:37:31 -0700939 if (mapping)
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700940 ret = page_mkclean_file(mapping, page);
941 }
942
943 return ret;
944}
Jaya Kumar60b59be2007-05-08 00:37:37 -0700945EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700946
Linus Torvalds1da177e2005-04-16 15:20:36 -0700947/**
Rik van Rielc44b6742010-03-05 13:42:09 -0800948 * page_move_anon_rmap - move a page to our anon_vma
949 * @page: the page to move to our anon_vma
950 * @vma: the vma the page belongs to
951 * @address: the user virtual address mapped
952 *
953 * When a page belongs exclusively to one process after a COW event,
954 * that page can be moved into the anon_vma that belongs to just that
955 * process, so the rmap code will not search the parent or sibling
956 * processes.
957 */
958void page_move_anon_rmap(struct page *page,
959 struct vm_area_struct *vma, unsigned long address)
960{
961 struct anon_vma *anon_vma = vma->anon_vma;
962
963 VM_BUG_ON(!PageLocked(page));
964 VM_BUG_ON(!anon_vma);
965 VM_BUG_ON(page->index != linear_page_index(vma, address));
966
967 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
968 page->mapping = (struct address_space *) anon_vma;
969}
970
971/**
Andi Kleen4e1c1972010-09-22 12:43:56 +0200972 * __page_set_anon_rmap - set up new anonymous rmap
973 * @page: Page to add to rmap
974 * @vma: VM area to add page to.
975 * @address: User virtual address of the mapping
Rik van Riele8a03fe2010-04-14 17:59:28 -0400976 * @exclusive: the page is exclusively owned by the current process
Nick Piggin9617d952006-01-06 00:11:12 -0800977 */
978static void __page_set_anon_rmap(struct page *page,
Rik van Riele8a03fe2010-04-14 17:59:28 -0400979 struct vm_area_struct *vma, unsigned long address, int exclusive)
Nick Piggin9617d952006-01-06 00:11:12 -0800980{
Rik van Riele8a03fe2010-04-14 17:59:28 -0400981 struct anon_vma *anon_vma = vma->anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -0800982
Rik van Riele8a03fe2010-04-14 17:59:28 -0400983 BUG_ON(!anon_vma);
Linus Torvaldsea900022010-04-12 12:44:29 -0700984
Andi Kleen4e1c1972010-09-22 12:43:56 +0200985 if (PageAnon(page))
986 return;
987
Linus Torvaldsea900022010-04-12 12:44:29 -0700988 /*
Rik van Riele8a03fe2010-04-14 17:59:28 -0400989 * If the page isn't exclusively mapped into this vma,
990 * we must use the _oldest_ possible anon_vma for the
991 * page mapping!
Linus Torvaldsea900022010-04-12 12:44:29 -0700992 */
Andi Kleen4e1c1972010-09-22 12:43:56 +0200993 if (!exclusive)
Andrea Arcangeli288468c2010-08-09 17:19:09 -0700994 anon_vma = anon_vma->root;
Linus Torvaldsea900022010-04-12 12:44:29 -0700995
Nick Piggin9617d952006-01-06 00:11:12 -0800996 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
997 page->mapping = (struct address_space *) anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -0800998 page->index = linear_page_index(vma, address);
Nick Piggin9617d952006-01-06 00:11:12 -0800999}
1000
1001/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001002 * __page_check_anon_rmap - sanity check anonymous rmap addition
Nick Pigginc97a9e12007-05-16 22:11:21 -07001003 * @page: the page to add the mapping to
1004 * @vma: the vm area in which the mapping is added
1005 * @address: the user virtual address mapped
1006 */
1007static void __page_check_anon_rmap(struct page *page,
1008 struct vm_area_struct *vma, unsigned long address)
1009{
1010#ifdef CONFIG_DEBUG_VM
1011 /*
1012 * The page's anon-rmap details (mapping and index) are guaranteed to
1013 * be set up correctly at this point.
1014 *
1015 * We have exclusion against page_add_anon_rmap because the caller
1016 * always holds the page locked, except if called from page_dup_rmap,
1017 * in which case the page is already known to be setup.
1018 *
1019 * We have exclusion against page_add_new_anon_rmap because those pages
1020 * are initially only visible via the pagetables, and the pte is locked
1021 * over the call to page_add_new_anon_rmap.
1022 */
Andrea Arcangeli44ab57a2010-08-09 17:19:10 -07001023 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
Nick Pigginc97a9e12007-05-16 22:11:21 -07001024 BUG_ON(page->index != linear_page_index(vma, address));
1025#endif
1026}
1027
1028/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001029 * page_add_anon_rmap - add pte mapping to an anonymous page
1030 * @page: the page to add the mapping to
1031 * @vma: the vm area in which the mapping is added
1032 * @address: the user virtual address mapped
1033 *
Hugh Dickins5ad64682009-12-14 17:59:24 -08001034 * The caller needs to hold the pte lock, and the page must be locked in
Hugh Dickins80e148222009-12-14 17:59:29 -08001035 * the anon_vma case: to serialize mapping,index checking after setting,
1036 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1037 * (but PageKsm is never downgraded to PageAnon).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001038 */
1039void page_add_anon_rmap(struct page *page,
1040 struct vm_area_struct *vma, unsigned long address)
1041{
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001042 do_page_add_anon_rmap(page, vma, address, 0);
1043}
1044
1045/*
1046 * Special version of the above for do_swap_page, which often runs
1047 * into pages that are exclusively owned by the current process.
1048 * Everybody else should continue to use page_add_anon_rmap above.
1049 */
1050void do_page_add_anon_rmap(struct page *page,
1051 struct vm_area_struct *vma, unsigned long address, int exclusive)
1052{
Hugh Dickins5ad64682009-12-14 17:59:24 -08001053 int first = atomic_inc_and_test(&page->_mapcount);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001054 if (first) {
Kirill A. Shutemov3cd14fc2013-09-12 15:13:58 -07001055 if (PageTransHuge(page))
Andrea Arcangeli79134172011-01-13 15:46:58 -08001056 __inc_zone_page_state(page,
1057 NR_ANON_TRANSPARENT_HUGEPAGES);
Kirill A. Shutemov3cd14fc2013-09-12 15:13:58 -07001058 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
1059 hpage_nr_pages(page));
Andrea Arcangeli79134172011-01-13 15:46:58 -08001060 }
Hugh Dickins5ad64682009-12-14 17:59:24 -08001061 if (unlikely(PageKsm(page)))
1062 return;
1063
Nick Pigginc97a9e12007-05-16 22:11:21 -07001064 VM_BUG_ON(!PageLocked(page));
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001065 /* address might be in next vma when migration races vma_adjust */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001066 if (first)
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001067 __page_set_anon_rmap(page, vma, address, exclusive);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001068 else
Nick Pigginc97a9e12007-05-16 22:11:21 -07001069 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001070}
1071
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001072/**
Nick Piggin9617d952006-01-06 00:11:12 -08001073 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1074 * @page: the page to add the mapping to
1075 * @vma: the vm area in which the mapping is added
1076 * @address: the user virtual address mapped
1077 *
1078 * Same as page_add_anon_rmap but must only be called on *new* pages.
1079 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -07001080 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -08001081 */
1082void page_add_new_anon_rmap(struct page *page,
1083 struct vm_area_struct *vma, unsigned long address)
1084{
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001085 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001086 SetPageSwapBacked(page);
1087 atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
Kirill A. Shutemov3cd14fc2013-09-12 15:13:58 -07001088 if (PageTransHuge(page))
Andrea Arcangeli79134172011-01-13 15:46:58 -08001089 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
Kirill A. Shutemov3cd14fc2013-09-12 15:13:58 -07001090 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
1091 hpage_nr_pages(page));
Rik van Riele8a03fe2010-04-14 17:59:28 -04001092 __page_set_anon_rmap(page, vma, address, 1);
Mel Gormanc53954a2013-07-03 15:02:34 -07001093 if (!mlocked_vma_newpage(vma, page)) {
1094 SetPageActive(page);
1095 lru_cache_add(page);
1096 } else
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001097 add_page_to_unevictable_list(page);
Nick Piggin9617d952006-01-06 00:11:12 -08001098}
1099
Linus Torvalds1da177e2005-04-16 15:20:36 -07001100/**
1101 * page_add_file_rmap - add pte mapping to a file page
1102 * @page: the page to add the mapping to
1103 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001104 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001105 */
1106void page_add_file_rmap(struct page *page)
1107{
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001108 bool locked;
1109 unsigned long flags;
1110
1111 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
Balbir Singhd69b0422009-06-17 16:26:34 -07001112 if (atomic_inc_and_test(&page->_mapcount)) {
Christoph Lameter65ba55f2006-06-30 01:55:34 -07001113 __inc_zone_page_state(page, NR_FILE_MAPPED);
Sha Zhengju68b48762013-09-12 15:13:50 -07001114 mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
Balbir Singhd69b0422009-06-17 16:26:34 -07001115 }
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001116 mem_cgroup_end_update_page_stat(page, &locked, &flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001117}
1118
1119/**
1120 * page_remove_rmap - take down pte mapping from a page
1121 * @page: page to remove mapping from
1122 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001123 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001124 */
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001125void page_remove_rmap(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001126{
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001127 bool anon = PageAnon(page);
1128 bool locked;
1129 unsigned long flags;
1130
1131 /*
1132 * The anon case has no mem_cgroup page_stat to update; but may
1133 * uncharge_page() below, where the lock ordering can deadlock if
1134 * we hold the lock against page_stat move: so avoid it on anon.
1135 */
1136 if (!anon)
1137 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
1138
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001139 /* page still mapped by someone else? */
1140 if (!atomic_add_negative(-1, &page->_mapcount))
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001141 goto out;
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001142
1143 /*
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001144 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
1145 * and not charged by memcg for now.
1146 */
1147 if (unlikely(PageHuge(page)))
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001148 goto out;
1149 if (anon) {
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001150 mem_cgroup_uncharge_page(page);
Kirill A. Shutemov3cd14fc2013-09-12 15:13:58 -07001151 if (PageTransHuge(page))
Andrea Arcangeli79134172011-01-13 15:46:58 -08001152 __dec_zone_page_state(page,
1153 NR_ANON_TRANSPARENT_HUGEPAGES);
Kirill A. Shutemov3cd14fc2013-09-12 15:13:58 -07001154 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
1155 -hpage_nr_pages(page));
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001156 } else {
1157 __dec_zone_page_state(page, NR_FILE_MAPPED);
Sha Zhengju68b48762013-09-12 15:13:50 -07001158 mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001159 mem_cgroup_end_update_page_stat(page, &locked, &flags);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001160 }
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001161 if (unlikely(PageMlocked(page)))
1162 clear_page_mlock(page);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001163 /*
1164 * It would be tidy to reset the PageAnon mapping here,
1165 * but that might overwrite a racing page_add_anon_rmap
1166 * which increments mapcount after us but sets mapping
1167 * before us: so leave the reset to free_hot_cold_page,
1168 * and remember that it's only reliable while mapped.
1169 * Leaving it set also helps swapoff to reinstate ptes
1170 * faster for those pages still in swapcache.
1171 */
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001172 return;
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001173out:
1174 if (!anon)
1175 mem_cgroup_end_update_page_stat(page, &locked, &flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001176}
1177
1178/*
1179 * Subfunctions of try_to_unmap: try_to_unmap_one called
Wanlong Gao99ef0312011-10-31 17:08:51 -07001180 * repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001181 */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001182int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1183 unsigned long address, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184{
1185 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001186 pte_t *pte;
1187 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001188 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 int ret = SWAP_AGAIN;
1190
Nick Piggin479db0b2008-08-20 14:09:18 -07001191 pte = page_check_address(page, mm, address, &ptl, 0);
Hugh Dickinsc0718802005-10-29 18:16:31 -07001192 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -07001193 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194
1195 /*
1196 * If the page is mlock()d, we cannot swap it out.
1197 * If it's recently referenced (perhaps page_referenced
1198 * skipped over this mm) then we should reactivate it.
1199 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001200 if (!(flags & TTU_IGNORE_MLOCK)) {
KOSAKI Motohirocaed0f482009-12-14 17:59:45 -08001201 if (vma->vm_flags & VM_LOCKED)
1202 goto out_mlock;
1203
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001204 if (TTU_ACTION(flags) == TTU_MUNLOCK)
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001205 goto out_unmap;
Andi Kleen14fa31b2009-09-16 11:50:10 +02001206 }
1207 if (!(flags & TTU_IGNORE_ACCESS)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001208 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1209 ret = SWAP_FAIL;
1210 goto out_unmap;
1211 }
1212 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001213
Linus Torvalds1da177e2005-04-16 15:20:36 -07001214 /* Nuke the page table entry. */
1215 flush_cache_page(vma, address, page_to_pfn(page));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001216 pteval = ptep_clear_flush(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001217
1218 /* Move the dirty bit to the physical page now the pte is gone. */
1219 if (pte_dirty(pteval))
1220 set_page_dirty(page);
1221
Hugh Dickins365e9c872005-10-29 18:16:18 -07001222 /* Update high watermark before we lower rss */
1223 update_hiwater_rss(mm);
1224
Andi Kleen888b9f72009-09-16 11:50:11 +02001225 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
Naoya Horiguchi5f24ae52012-12-12 13:52:30 -08001226 if (!PageHuge(page)) {
1227 if (PageAnon(page))
1228 dec_mm_counter(mm, MM_ANONPAGES);
1229 else
1230 dec_mm_counter(mm, MM_FILEPAGES);
1231 }
Andi Kleen888b9f72009-09-16 11:50:11 +02001232 set_pte_at(mm, address, pte,
Naoya Horiguchi5f24ae52012-12-12 13:52:30 -08001233 swp_entry_to_pte(make_hwpoison_entry(page)));
Andi Kleen888b9f72009-09-16 11:50:11 +02001234 } else if (PageAnon(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001235 swp_entry_t entry = { .val = page_private(page) };
Cyrill Gorcunov179ef712013-08-13 16:00:49 -07001236 pte_t swp_pte;
Christoph Lameter06972122006-06-23 02:03:35 -07001237
1238 if (PageSwapCache(page)) {
1239 /*
1240 * Store the swap location in the pte.
1241 * See handle_pte_fault() ...
1242 */
Hugh Dickins570a335b2009-12-14 17:58:46 -08001243 if (swap_duplicate(entry) < 0) {
1244 set_pte_at(mm, address, pte, pteval);
1245 ret = SWAP_FAIL;
1246 goto out_unmap;
1247 }
Christoph Lameter06972122006-06-23 02:03:35 -07001248 if (list_empty(&mm->mmlist)) {
1249 spin_lock(&mmlist_lock);
1250 if (list_empty(&mm->mmlist))
1251 list_add(&mm->mmlist, &init_mm.mmlist);
1252 spin_unlock(&mmlist_lock);
1253 }
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001254 dec_mm_counter(mm, MM_ANONPAGES);
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -08001255 inc_mm_counter(mm, MM_SWAPENTS);
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001256 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
Christoph Lameter06972122006-06-23 02:03:35 -07001257 /*
1258 * Store the pfn of the page in a special migration
1259 * pte. do_swap_page() will wait until the migration
1260 * pte is removed and then restart fault handling.
1261 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001262 BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION);
Christoph Lameter06972122006-06-23 02:03:35 -07001263 entry = make_migration_entry(page, pte_write(pteval));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001264 }
Cyrill Gorcunov179ef712013-08-13 16:00:49 -07001265 swp_pte = swp_entry_to_pte(entry);
1266 if (pte_soft_dirty(pteval))
1267 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1268 set_pte_at(mm, address, pte, swp_pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001269 BUG_ON(pte_file(*pte));
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001270 } else if (IS_ENABLED(CONFIG_MIGRATION) &&
1271 (TTU_ACTION(flags) == TTU_MIGRATION)) {
Christoph Lameter04e62a22006-06-23 02:03:38 -07001272 /* Establish migration entry for a file page */
1273 swp_entry_t entry;
1274 entry = make_migration_entry(page, pte_write(pteval));
1275 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1276 } else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001277 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001278
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001279 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001280 page_cache_release(page);
1281
1282out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -07001283 pte_unmap_unlock(pte, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001284 if (ret != SWAP_FAIL)
1285 mmu_notifier_invalidate_page(mm, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001286out:
1287 return ret;
KOSAKI Motohirocaed0f482009-12-14 17:59:45 -08001288
1289out_mlock:
1290 pte_unmap_unlock(pte, ptl);
1291
1292
1293 /*
1294 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
1295 * unstable result and race. Plus, We can't wait here because
Ingo Molnar5a505082012-12-02 19:56:46 +00001296 * we now hold anon_vma->rwsem or mapping->i_mmap_mutex.
KOSAKI Motohirocaed0f482009-12-14 17:59:45 -08001297 * if trylock failed, the page remain in evictable lru and later
1298 * vmscan could retry to move the page to unevictable lru if the
1299 * page is actually mlocked.
1300 */
1301 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
1302 if (vma->vm_flags & VM_LOCKED) {
1303 mlock_vma_page(page);
1304 ret = SWAP_MLOCK;
1305 }
1306 up_read(&vma->vm_mm->mmap_sem);
1307 }
1308 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001309}
1310
1311/*
1312 * objrmap doesn't work for nonlinear VMAs because the assumption that
1313 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
1314 * Consequently, given a particular page and its ->index, we cannot locate the
1315 * ptes which are mapping that page without an exhaustive linear search.
1316 *
1317 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
1318 * maps the file to which the target page belongs. The ->vm_private_data field
1319 * holds the current cursor into that scan. Successive searches will circulate
1320 * around the vma's virtual address space.
1321 *
1322 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
1323 * more scanning pressure is placed against them as well. Eventually pages
1324 * will become fully unmapped and are eligible for eviction.
1325 *
1326 * For very sparsely populated VMAs this is a little inefficient - chances are
1327 * there there won't be many ptes located within the scan cluster. In this case
1328 * maybe we could scan further - to the end of the pte page, perhaps.
Nick Pigginb291f002008-10-18 20:26:44 -07001329 *
1330 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
1331 * acquire it without blocking. If vma locked, mlock the pages in the cluster,
1332 * rather than unmapping them. If we encounter the "check_page" that vmscan is
1333 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001334 */
1335#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
1336#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
1337
Nick Pigginb291f002008-10-18 20:26:44 -07001338static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
1339 struct vm_area_struct *vma, struct page *check_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001340{
1341 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001342 pmd_t *pmd;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001343 pte_t *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001345 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346 struct page *page;
1347 unsigned long address;
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001348 unsigned long mmun_start; /* For mmu_notifiers */
1349 unsigned long mmun_end; /* For mmu_notifiers */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001350 unsigned long end;
Nick Pigginb291f002008-10-18 20:26:44 -07001351 int ret = SWAP_AGAIN;
1352 int locked_vma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001353
Linus Torvalds1da177e2005-04-16 15:20:36 -07001354 address = (vma->vm_start + cursor) & CLUSTER_MASK;
1355 end = address + CLUSTER_SIZE;
1356 if (address < vma->vm_start)
1357 address = vma->vm_start;
1358 if (end > vma->vm_end)
1359 end = vma->vm_end;
1360
Bob Liu62190492012-12-11 16:00:37 -08001361 pmd = mm_find_pmd(mm, address);
1362 if (!pmd)
Nick Pigginb291f002008-10-18 20:26:44 -07001363 return ret;
1364
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001365 mmun_start = address;
1366 mmun_end = end;
1367 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1368
Nick Pigginb291f002008-10-18 20:26:44 -07001369 /*
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001370 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
Nick Pigginb291f002008-10-18 20:26:44 -07001371 * keep the sem while scanning the cluster for mlocking pages.
1372 */
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001373 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001374 locked_vma = (vma->vm_flags & VM_LOCKED);
1375 if (!locked_vma)
1376 up_read(&vma->vm_mm->mmap_sem); /* don't need it */
1377 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001378
1379 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001380
Hugh Dickins365e9c872005-10-29 18:16:18 -07001381 /* Update high watermark before we lower rss */
1382 update_hiwater_rss(mm);
1383
Hugh Dickinsc0718802005-10-29 18:16:31 -07001384 for (; address < end; pte++, address += PAGE_SIZE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001385 if (!pte_present(*pte))
1386 continue;
Linus Torvalds6aab3412005-11-28 14:34:23 -08001387 page = vm_normal_page(vma, address, *pte);
1388 BUG_ON(!page || PageAnon(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389
Nick Pigginb291f002008-10-18 20:26:44 -07001390 if (locked_vma) {
1391 mlock_vma_page(page); /* no-op if already mlocked */
1392 if (page == check_page)
1393 ret = SWAP_MLOCK;
1394 continue; /* don't unmap */
1395 }
1396
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001397 if (ptep_clear_flush_young_notify(vma, address, pte))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001398 continue;
1399
1400 /* Nuke the page table entry. */
Ben Collinseca35132005-11-29 11:45:26 -08001401 flush_cache_page(vma, address, pte_pfn(*pte));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001402 pteval = ptep_clear_flush(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
1404 /* If nonlinear, store the file page offset in the pte. */
Cyrill Gorcunov41bb3472013-08-13 16:00:51 -07001405 if (page->index != linear_page_index(vma, address)) {
1406 pte_t ptfile = pgoff_to_pte(page->index);
1407 if (pte_soft_dirty(pteval))
1408 pte_file_mksoft_dirty(ptfile);
1409 set_pte_at(mm, address, pte, ptfile);
1410 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001411
1412 /* Move the dirty bit to the physical page now the pte is gone. */
1413 if (pte_dirty(pteval))
1414 set_page_dirty(page);
1415
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001416 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 page_cache_release(page);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001418 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419 (*mapcount)--;
1420 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001421 pte_unmap_unlock(pte - 1, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001422 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
Nick Pigginb291f002008-10-18 20:26:44 -07001423 if (locked_vma)
1424 up_read(&vma->vm_mm->mmap_sem);
1425 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426}
1427
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001428bool is_vma_temporary_stack(struct vm_area_struct *vma)
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001429{
1430 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1431
1432 if (!maybe_stack)
1433 return false;
1434
1435 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1436 VM_STACK_INCOMPLETE_SETUP)
1437 return true;
1438
1439 return false;
1440}
1441
Nick Pigginb291f002008-10-18 20:26:44 -07001442/**
1443 * try_to_unmap_anon - unmap or unlock anonymous page using the object-based
1444 * rmap method
1445 * @page: the page to unmap/unlock
Huang Shijie8051be52009-12-14 17:58:50 -08001446 * @flags: action and flags
Nick Pigginb291f002008-10-18 20:26:44 -07001447 *
1448 * Find all the mappings of a page using the mapping pointer and the vma chains
1449 * contained in the anon_vma struct it points to.
1450 *
1451 * This function is only called from try_to_unmap/try_to_munlock for
1452 * anonymous pages.
1453 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1454 * where the page was found will be held for write. So, we won't recheck
1455 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1456 * 'LOCKED.
1457 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001458static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459{
1460 struct anon_vma *anon_vma;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001461 pgoff_t pgoff;
Rik van Riel5beb4932010-03-05 13:42:07 -08001462 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001463 int ret = SWAP_AGAIN;
Nick Pigginb291f002008-10-18 20:26:44 -07001464
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00001465 anon_vma = page_lock_anon_vma_read(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466 if (!anon_vma)
1467 return ret;
1468
Michel Lespinassebf181b92012-10-08 16:31:39 -07001469 pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1470 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -08001471 struct vm_area_struct *vma = avc->vma;
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001472 unsigned long address;
1473
1474 /*
1475 * During exec, a temporary VMA is setup and later moved.
1476 * The VMA is moved under the anon_vma lock but not the
1477 * page tables leading to a race where migration cannot
1478 * find the migration ptes. Rather than increasing the
1479 * locking requirements of exec(), migration skips
1480 * temporary VMAs until after exec() completes.
1481 */
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001482 if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) &&
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001483 is_vma_temporary_stack(vma))
1484 continue;
1485
1486 address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -08001487 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001488 if (ret != SWAP_AGAIN || !page_mapped(page))
1489 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001490 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -08001491
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00001492 page_unlock_anon_vma_read(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493 return ret;
1494}
1495
1496/**
Nick Pigginb291f002008-10-18 20:26:44 -07001497 * try_to_unmap_file - unmap/unlock file page using the object-based rmap method
1498 * @page: the page to unmap/unlock
Andi Kleen14fa31b2009-09-16 11:50:10 +02001499 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 *
1501 * Find all the mappings of a page using the mapping pointer and the vma chains
1502 * contained in the address_space struct it points to.
1503 *
Nick Pigginb291f002008-10-18 20:26:44 -07001504 * This function is only called from try_to_unmap/try_to_munlock for
1505 * object-based pages.
1506 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1507 * where the page was found will be held for write. So, we won't recheck
1508 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1509 * 'LOCKED.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001510 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001511static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001512{
1513 struct address_space *mapping = page->mapping;
1514 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1515 struct vm_area_struct *vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001516 int ret = SWAP_AGAIN;
1517 unsigned long cursor;
1518 unsigned long max_nl_cursor = 0;
1519 unsigned long max_nl_size = 0;
1520 unsigned int mapcount;
1521
Hillf Danton369a7132013-04-29 15:06:14 -07001522 if (PageHuge(page))
1523 pgoff = page->index << compound_order(page);
1524
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001525 mutex_lock(&mapping->i_mmap_mutex);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001526 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -08001527 unsigned long address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -08001528 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001529 if (ret != SWAP_AGAIN || !page_mapped(page))
1530 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001531 }
1532
1533 if (list_empty(&mapping->i_mmap_nonlinear))
1534 goto out;
1535
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001536 /*
1537 * We don't bother to try to find the munlocked page in nonlinears.
1538 * It's costly. Instead, later, page reclaim logic may call
1539 * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily.
1540 */
1541 if (TTU_ACTION(flags) == TTU_MUNLOCK)
1542 goto out;
1543
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001545 shared.nonlinear) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546 cursor = (unsigned long) vma->vm_private_data;
1547 if (cursor > max_nl_cursor)
1548 max_nl_cursor = cursor;
1549 cursor = vma->vm_end - vma->vm_start;
1550 if (cursor > max_nl_size)
1551 max_nl_size = cursor;
1552 }
1553
Nick Pigginb291f002008-10-18 20:26:44 -07001554 if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001555 ret = SWAP_FAIL;
1556 goto out;
1557 }
1558
1559 /*
1560 * We don't try to search for this page in the nonlinear vmas,
1561 * and page_referenced wouldn't have found it anyway. Instead
1562 * just walk the nonlinear vmas trying to age and unmap some.
1563 * The mapcount of the page we came in with is irrelevant,
1564 * but even so use it as a guide to how hard we should try?
1565 */
1566 mapcount = page_mapcount(page);
1567 if (!mapcount)
1568 goto out;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001569 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001570
1571 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
1572 if (max_nl_cursor == 0)
1573 max_nl_cursor = CLUSTER_SIZE;
1574
1575 do {
1576 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001577 shared.nonlinear) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 cursor = (unsigned long) vma->vm_private_data;
Hugh Dickins839b9682005-09-03 15:54:43 -07001579 while ( cursor < max_nl_cursor &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 cursor < vma->vm_end - vma->vm_start) {
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001581 if (try_to_unmap_cluster(cursor, &mapcount,
1582 vma, page) == SWAP_MLOCK)
1583 ret = SWAP_MLOCK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584 cursor += CLUSTER_SIZE;
1585 vma->vm_private_data = (void *) cursor;
1586 if ((int)mapcount <= 0)
1587 goto out;
1588 }
1589 vma->vm_private_data = (void *) max_nl_cursor;
1590 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001591 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001592 max_nl_cursor += CLUSTER_SIZE;
1593 } while (max_nl_cursor <= max_nl_size);
1594
1595 /*
1596 * Don't loop forever (perhaps all the remaining pages are
1597 * in locked vmas). Reset cursor on all unreserved nonlinear
1598 * vmas, now forgetting on which ones it had fallen behind.
1599 */
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001600 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear)
Hugh Dickins101d2be2005-11-21 21:32:16 -08001601 vma->vm_private_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001602out:
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001603 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604 return ret;
1605}
1606
1607/**
1608 * try_to_unmap - try to remove all page table mappings to a page
1609 * @page: the page to get unmapped
Andi Kleen14fa31b2009-09-16 11:50:10 +02001610 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001611 *
1612 * Tries to remove all the page table entries which are mapping this
1613 * page, used in the pageout path. Caller must hold the page lock.
1614 * Return values are:
1615 *
1616 * SWAP_SUCCESS - we succeeded in removing all mappings
1617 * SWAP_AGAIN - we missed a mapping, try again later
1618 * SWAP_FAIL - the page is unswappable
Nick Pigginb291f002008-10-18 20:26:44 -07001619 * SWAP_MLOCK - page is mlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001620 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001621int try_to_unmap(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001622{
1623 int ret;
1624
Linus Torvalds1da177e2005-04-16 15:20:36 -07001625 BUG_ON(!PageLocked(page));
Andrea Arcangeli91600e92011-01-13 15:47:16 -08001626 VM_BUG_ON(!PageHuge(page) && PageTransHuge(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001627
Hugh Dickins5ad64682009-12-14 17:59:24 -08001628 if (unlikely(PageKsm(page)))
1629 ret = try_to_unmap_ksm(page, flags);
1630 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001631 ret = try_to_unmap_anon(page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001632 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001633 ret = try_to_unmap_file(page, flags);
Nick Pigginb291f002008-10-18 20:26:44 -07001634 if (ret != SWAP_MLOCK && !page_mapped(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001635 ret = SWAP_SUCCESS;
1636 return ret;
1637}
Nikita Danilov81b40822005-05-01 08:58:36 -07001638
Nick Pigginb291f002008-10-18 20:26:44 -07001639/**
1640 * try_to_munlock - try to munlock a page
1641 * @page: the page to be munlocked
1642 *
1643 * Called from munlock code. Checks all of the VMAs mapping the page
1644 * to make sure nobody else has this page mlocked. The page will be
1645 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1646 *
1647 * Return values are:
1648 *
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001649 * SWAP_AGAIN - no vma is holding page mlocked, or,
Nick Pigginb291f002008-10-18 20:26:44 -07001650 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
Hugh Dickins5ad64682009-12-14 17:59:24 -08001651 * SWAP_FAIL - page cannot be located at present
Nick Pigginb291f002008-10-18 20:26:44 -07001652 * SWAP_MLOCK - page is now mlocked.
1653 */
1654int try_to_munlock(struct page *page)
1655{
1656 VM_BUG_ON(!PageLocked(page) || PageLRU(page));
1657
Hugh Dickins5ad64682009-12-14 17:59:24 -08001658 if (unlikely(PageKsm(page)))
1659 return try_to_unmap_ksm(page, TTU_MUNLOCK);
1660 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001661 return try_to_unmap_anon(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001662 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001663 return try_to_unmap_file(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001664}
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001665
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001666void __put_anon_vma(struct anon_vma *anon_vma)
Rik van Riel76545062010-08-09 17:18:41 -07001667{
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001668 struct anon_vma *root = anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -07001669
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001670 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1671 anon_vma_free(root);
Rik van Riel76545062010-08-09 17:18:41 -07001672
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001673 anon_vma_free(anon_vma);
Rik van Riel76545062010-08-09 17:18:41 -07001674}
Rik van Riel76545062010-08-09 17:18:41 -07001675
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001676#ifdef CONFIG_MIGRATION
1677/*
1678 * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
1679 * Called by migrate.c to remove migration ptes, but might be used more later.
1680 */
1681static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
1682 struct vm_area_struct *, unsigned long, void *), void *arg)
1683{
1684 struct anon_vma *anon_vma;
Michel Lespinassebf181b92012-10-08 16:31:39 -07001685 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
Rik van Riel5beb4932010-03-05 13:42:07 -08001686 struct anon_vma_chain *avc;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001687 int ret = SWAP_AGAIN;
1688
1689 /*
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00001690 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001691 * because that depends on page_mapped(); but not all its usages
Mel Gorman3f6c8272010-05-24 14:32:17 -07001692 * are holding mmap_sem. Users without mmap_sem are required to
1693 * take a reference count to prevent the anon_vma disappearing
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001694 */
1695 anon_vma = page_anon_vma(page);
1696 if (!anon_vma)
1697 return ret;
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00001698 anon_vma_lock_read(anon_vma);
Michel Lespinassebf181b92012-10-08 16:31:39 -07001699 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -08001700 struct vm_area_struct *vma = avc->vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001701 unsigned long address = vma_address(page, vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001702 ret = rmap_one(page, vma, address, arg);
1703 if (ret != SWAP_AGAIN)
1704 break;
1705 }
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00001706 anon_vma_unlock_read(anon_vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001707 return ret;
1708}
1709
1710static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *,
1711 struct vm_area_struct *, unsigned long, void *), void *arg)
1712{
1713 struct address_space *mapping = page->mapping;
1714 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1715 struct vm_area_struct *vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001716 int ret = SWAP_AGAIN;
1717
1718 if (!mapping)
1719 return ret;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001720 mutex_lock(&mapping->i_mmap_mutex);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001721 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001722 unsigned long address = vma_address(page, vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001723 ret = rmap_one(page, vma, address, arg);
1724 if (ret != SWAP_AGAIN)
1725 break;
1726 }
1727 /*
1728 * No nonlinear handling: being always shared, nonlinear vmas
1729 * never contain migration ptes. Decide what to do about this
1730 * limitation to linear when we need rmap_walk() on nonlinear.
1731 */
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001732 mutex_unlock(&mapping->i_mmap_mutex);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001733 return ret;
1734}
1735
1736int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
1737 struct vm_area_struct *, unsigned long, void *), void *arg)
1738{
1739 VM_BUG_ON(!PageLocked(page));
1740
1741 if (unlikely(PageKsm(page)))
1742 return rmap_walk_ksm(page, rmap_one, arg);
1743 else if (PageAnon(page))
1744 return rmap_walk_anon(page, rmap_one, arg);
1745 else
1746 return rmap_walk_file(page, rmap_one, arg);
1747}
1748#endif /* CONFIG_MIGRATION */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001749
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001750#ifdef CONFIG_HUGETLB_PAGE
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001751/*
1752 * The following three functions are for anonymous (private mapped) hugepages.
1753 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1754 * and no lru code, because we handle hugepages differently from common pages.
1755 */
1756static void __hugepage_set_anon_rmap(struct page *page,
1757 struct vm_area_struct *vma, unsigned long address, int exclusive)
1758{
1759 struct anon_vma *anon_vma = vma->anon_vma;
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001760
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001761 BUG_ON(!anon_vma);
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001762
1763 if (PageAnon(page))
1764 return;
1765 if (!exclusive)
1766 anon_vma = anon_vma->root;
1767
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001768 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1769 page->mapping = (struct address_space *) anon_vma;
1770 page->index = linear_page_index(vma, address);
1771}
1772
1773void hugepage_add_anon_rmap(struct page *page,
1774 struct vm_area_struct *vma, unsigned long address)
1775{
1776 struct anon_vma *anon_vma = vma->anon_vma;
1777 int first;
Naoya Horiguchia850ea32010-09-10 13:23:06 +09001778
1779 BUG_ON(!PageLocked(page));
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001780 BUG_ON(!anon_vma);
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001781 /* address might be in next vma when migration races vma_adjust */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001782 first = atomic_inc_and_test(&page->_mapcount);
1783 if (first)
1784 __hugepage_set_anon_rmap(page, vma, address, 0);
1785}
1786
1787void hugepage_add_new_anon_rmap(struct page *page,
1788 struct vm_area_struct *vma, unsigned long address)
1789{
1790 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1791 atomic_set(&page->_mapcount, 0);
1792 __hugepage_set_anon_rmap(page, vma, address, 1);
1793}
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001794#endif /* CONFIG_HUGETLB_PAGE */