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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>
Linus Torvalds1da177e2005-04-16 15:20:36 -070059
60#include <asm/tlbflush.h>
61
Nick Pigginb291f002008-10-18 20:26:44 -070062#include "internal.h"
63
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070064static struct kmem_cache *anon_vma_cachep;
Rik van Riel5beb4932010-03-05 13:42:07 -080065static struct kmem_cache *anon_vma_chain_cachep;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070066
67static inline struct anon_vma *anon_vma_alloc(void)
68{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070069 struct anon_vma *anon_vma;
70
71 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
72 if (anon_vma) {
73 atomic_set(&anon_vma->refcount, 1);
74 /*
75 * Initialise the anon_vma root to point to itself. If called
76 * from fork, the root will be reset to the parents anon_vma.
77 */
78 anon_vma->root = anon_vma;
79 }
80
81 return anon_vma;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070082}
83
Peter Zijlstra01d8b202011-03-22 16:32:49 -070084static inline void anon_vma_free(struct anon_vma *anon_vma)
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070085{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070086 VM_BUG_ON(atomic_read(&anon_vma->refcount));
Peter Zijlstra88c22082011-05-24 17:12:13 -070087
88 /*
89 * Synchronize against page_lock_anon_vma() such that
90 * we can safely hold the lock without the anon_vma getting
91 * freed.
92 *
93 * Relies on the full mb implied by the atomic_dec_and_test() from
94 * put_anon_vma() against the acquire barrier implied by
95 * mutex_trylock() from page_lock_anon_vma(). This orders:
96 *
97 * page_lock_anon_vma() VS put_anon_vma()
98 * mutex_trylock() atomic_dec_and_test()
99 * LOCK MB
100 * atomic_read() mutex_is_locked()
101 *
102 * LOCK should suffice since the actual taking of the lock must
103 * happen _before_ what follows.
104 */
105 if (mutex_is_locked(&anon_vma->root->mutex)) {
106 anon_vma_lock(anon_vma);
107 anon_vma_unlock(anon_vma);
108 }
109
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -0700110 kmem_cache_free(anon_vma_cachep, anon_vma);
111}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700112
Linus Torvaldsdd347392011-06-17 19:05:36 -0700113static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
Rik van Riel5beb4932010-03-05 13:42:07 -0800114{
Linus Torvaldsdd347392011-06-17 19:05:36 -0700115 return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
Rik van Riel5beb4932010-03-05 13:42:07 -0800116}
117
Namhyung Kime574b5f2010-10-26 14:22:02 -0700118static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
Rik van Riel5beb4932010-03-05 13:42:07 -0800119{
120 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
121}
122
Kautuk Consul6583a842012-03-21 16:34:01 -0700123static void anon_vma_chain_link(struct vm_area_struct *vma,
124 struct anon_vma_chain *avc,
125 struct anon_vma *anon_vma)
126{
127 avc->vma = vma;
128 avc->anon_vma = anon_vma;
129 list_add(&avc->same_vma, &vma->anon_vma_chain);
130
131 /*
132 * It's critical to add new vmas to the tail of the anon_vma,
133 * see comment in huge_memory.c:__split_huge_page().
134 */
135 list_add_tail(&avc->same_anon_vma, &anon_vma->head);
136}
137
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700138/**
139 * anon_vma_prepare - attach an anon_vma to a memory region
140 * @vma: the memory region in question
141 *
142 * This makes sure the memory mapping described by 'vma' has
143 * an 'anon_vma' attached to it, so that we can associate the
144 * anonymous pages mapped into it with that anon_vma.
145 *
146 * The common case will be that we already have one, but if
Figo.zhang23a07902010-12-27 15:14:06 +0100147 * not we either need to find an adjacent mapping that we
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700148 * can re-use the anon_vma from (very common when the only
149 * reason for splitting a vma has been mprotect()), or we
150 * allocate a new one.
151 *
152 * Anon-vma allocations are very subtle, because we may have
153 * optimistically looked up an anon_vma in page_lock_anon_vma()
154 * and that may actually touch the spinlock even in the newly
155 * allocated vma (it depends on RCU to make sure that the
156 * anon_vma isn't actually destroyed).
157 *
158 * As a result, we need to do proper anon_vma locking even
159 * for the new allocation. At the same time, we do not want
160 * to do any locking for the common case of already having
161 * an anon_vma.
162 *
163 * This must be called with the mmap_sem held for reading.
164 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165int anon_vma_prepare(struct vm_area_struct *vma)
166{
167 struct anon_vma *anon_vma = vma->anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800168 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
170 might_sleep();
171 if (unlikely(!anon_vma)) {
172 struct mm_struct *mm = vma->vm_mm;
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700173 struct anon_vma *allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
Linus Torvaldsdd347392011-06-17 19:05:36 -0700175 avc = anon_vma_chain_alloc(GFP_KERNEL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800176 if (!avc)
177 goto out_enomem;
178
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179 anon_vma = find_mergeable_anon_vma(vma);
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700180 allocated = NULL;
181 if (!anon_vma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700182 anon_vma = anon_vma_alloc();
183 if (unlikely(!anon_vma))
Rik van Riel5beb4932010-03-05 13:42:07 -0800184 goto out_enomem_free_avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 allocated = anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 }
187
Rik van Rielcba48b92010-08-09 17:18:38 -0700188 anon_vma_lock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700189 /* page_table_lock to protect against threads */
190 spin_lock(&mm->page_table_lock);
191 if (likely(!vma->anon_vma)) {
192 vma->anon_vma = anon_vma;
Kautuk Consul6583a842012-03-21 16:34:01 -0700193 anon_vma_chain_link(vma, avc, anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 allocated = NULL;
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400195 avc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700196 }
197 spin_unlock(&mm->page_table_lock);
Rik van Rielcba48b92010-08-09 17:18:38 -0700198 anon_vma_unlock(anon_vma);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400199
200 if (unlikely(allocated))
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700201 put_anon_vma(allocated);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400202 if (unlikely(avc))
Rik van Riel5beb4932010-03-05 13:42:07 -0800203 anon_vma_chain_free(avc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 }
205 return 0;
Rik van Riel5beb4932010-03-05 13:42:07 -0800206
207 out_enomem_free_avc:
208 anon_vma_chain_free(avc);
209 out_enomem:
210 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211}
212
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700213/*
214 * This is a useful helper function for locking the anon_vma root as
215 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
216 * have the same vma.
217 *
218 * Such anon_vma's should have the same root, so you'd expect to see
219 * just a single mutex_lock for the whole traversal.
220 */
221static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
222{
223 struct anon_vma *new_root = anon_vma->root;
224 if (new_root != root) {
225 if (WARN_ON_ONCE(root))
226 mutex_unlock(&root->mutex);
227 root = new_root;
228 mutex_lock(&root->mutex);
229 }
230 return root;
231}
232
233static inline void unlock_anon_vma_root(struct anon_vma *root)
234{
235 if (root)
236 mutex_unlock(&root->mutex);
237}
238
Rik van Riel5beb4932010-03-05 13:42:07 -0800239/*
240 * Attach the anon_vmas from src to dst.
241 * Returns 0 on success, -ENOMEM on failure.
242 */
243int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244{
Rik van Riel5beb4932010-03-05 13:42:07 -0800245 struct anon_vma_chain *avc, *pavc;
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700246 struct anon_vma *root = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700247
Linus Torvalds646d87b2010-04-11 17:15:03 -0700248 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700249 struct anon_vma *anon_vma;
250
Linus Torvaldsdd347392011-06-17 19:05:36 -0700251 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
252 if (unlikely(!avc)) {
253 unlock_anon_vma_root(root);
254 root = NULL;
255 avc = anon_vma_chain_alloc(GFP_KERNEL);
256 if (!avc)
257 goto enomem_failure;
258 }
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700259 anon_vma = pavc->anon_vma;
260 root = lock_anon_vma_root(root, anon_vma);
261 anon_vma_chain_link(dst, avc, anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262 }
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700263 unlock_anon_vma_root(root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800264 return 0;
265
266 enomem_failure:
267 unlink_anon_vmas(dst);
268 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700269}
270
Rik van Riel5beb4932010-03-05 13:42:07 -0800271/*
Andrea Arcangeli948f0172012-01-10 15:08:05 -0800272 * Some rmap walk that needs to find all ptes/hugepmds without false
273 * negatives (like migrate and split_huge_page) running concurrent
274 * with operations that copy or move pagetables (like mremap() and
275 * fork()) to be safe. They depend on the anon_vma "same_anon_vma"
276 * list to be in a certain order: the dst_vma must be placed after the
277 * src_vma in the list. This is always guaranteed by fork() but
278 * mremap() needs to call this function to enforce it in case the
279 * dst_vma isn't newly allocated and chained with the anon_vma_clone()
280 * function but just an extension of a pre-existing vma through
281 * vma_merge.
282 *
283 * NOTE: the same_anon_vma list can still be changed by other
284 * processes while mremap runs because mremap doesn't hold the
285 * anon_vma mutex to prevent modifications to the list while it
286 * runs. All we need to enforce is that the relative order of this
287 * process vmas isn't changing (we don't care about other vmas
288 * order). Each vma corresponds to an anon_vma_chain structure so
289 * there's no risk that other processes calling anon_vma_moveto_tail()
290 * and changing the same_anon_vma list under mremap() will screw with
291 * the relative order of this process vmas in the list, because we
292 * they can't alter the order of any vma that belongs to this
293 * process. And there can't be another anon_vma_moveto_tail() running
294 * concurrently with mremap() coming from this process because we hold
295 * the mmap_sem for the whole mremap(). fork() ordering dependency
296 * also shouldn't be affected because fork() only cares that the
297 * parent vmas are placed in the list before the child vmas and
298 * anon_vma_moveto_tail() won't reorder vmas from either the fork()
299 * parent or child.
300 */
301void anon_vma_moveto_tail(struct vm_area_struct *dst)
302{
303 struct anon_vma_chain *pavc;
304 struct anon_vma *root = NULL;
305
306 list_for_each_entry_reverse(pavc, &dst->anon_vma_chain, same_vma) {
307 struct anon_vma *anon_vma = pavc->anon_vma;
308 VM_BUG_ON(pavc->vma != dst);
309 root = lock_anon_vma_root(root, anon_vma);
310 list_del(&pavc->same_anon_vma);
311 list_add_tail(&pavc->same_anon_vma, &anon_vma->head);
312 }
313 unlock_anon_vma_root(root);
314}
315
316/*
Rik van Riel5beb4932010-03-05 13:42:07 -0800317 * Attach vma to its own anon_vma, as well as to the anon_vmas that
318 * the corresponding VMA in the parent process is attached to.
319 * Returns 0 on success, non-zero on failure.
320 */
321int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322{
Rik van Riel5beb4932010-03-05 13:42:07 -0800323 struct anon_vma_chain *avc;
324 struct anon_vma *anon_vma;
325
326 /* Don't bother if the parent process has no anon_vma here. */
327 if (!pvma->anon_vma)
328 return 0;
329
330 /*
331 * First, attach the new VMA to the parent VMA's anon_vmas,
332 * so rmap can find non-COWed pages in child processes.
333 */
334 if (anon_vma_clone(vma, pvma))
335 return -ENOMEM;
336
337 /* Then add our own anon_vma. */
338 anon_vma = anon_vma_alloc();
339 if (!anon_vma)
340 goto out_error;
Linus Torvaldsdd347392011-06-17 19:05:36 -0700341 avc = anon_vma_chain_alloc(GFP_KERNEL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800342 if (!avc)
343 goto out_error_free_anon_vma;
Rik van Riel5c341ee2010-08-09 17:18:39 -0700344
345 /*
346 * The root anon_vma's spinlock is the lock actually used when we
347 * lock any of the anon_vmas in this anon_vma tree.
348 */
349 anon_vma->root = pvma->anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -0700350 /*
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700351 * With refcounts, an anon_vma can stay around longer than the
352 * process it belongs to. The root anon_vma needs to be pinned until
353 * this anon_vma is freed, because the lock lives in the root.
Rik van Riel76545062010-08-09 17:18:41 -0700354 */
355 get_anon_vma(anon_vma->root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800356 /* Mark this anon_vma as the one where our new (COWed) pages go. */
357 vma->anon_vma = anon_vma;
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700358 anon_vma_lock(anon_vma);
Rik van Riel5c341ee2010-08-09 17:18:39 -0700359 anon_vma_chain_link(vma, avc, anon_vma);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700360 anon_vma_unlock(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800361
362 return 0;
363
364 out_error_free_anon_vma:
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700365 put_anon_vma(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800366 out_error:
Rik van Riel4946d542010-04-05 12:13:33 -0400367 unlink_anon_vmas(vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800368 return -ENOMEM;
369}
370
Rik van Riel5beb4932010-03-05 13:42:07 -0800371void unlink_anon_vmas(struct vm_area_struct *vma)
372{
373 struct anon_vma_chain *avc, *next;
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200374 struct anon_vma *root = NULL;
Rik van Riel5beb4932010-03-05 13:42:07 -0800375
Rik van Riel5c341ee2010-08-09 17:18:39 -0700376 /*
377 * Unlink each anon_vma chained to the VMA. This list is ordered
378 * from newest to oldest, ensuring the root anon_vma gets freed last.
379 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800380 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200381 struct anon_vma *anon_vma = avc->anon_vma;
382
383 root = lock_anon_vma_root(root, anon_vma);
384 list_del(&avc->same_anon_vma);
385
386 /*
387 * Leave empty anon_vmas on the list - we'll need
388 * to free them outside the lock.
389 */
390 if (list_empty(&anon_vma->head))
391 continue;
392
393 list_del(&avc->same_vma);
394 anon_vma_chain_free(avc);
395 }
396 unlock_anon_vma_root(root);
397
398 /*
399 * Iterate the list once more, it now only contains empty and unlinked
400 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
401 * needing to acquire the anon_vma->root->mutex.
402 */
403 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
404 struct anon_vma *anon_vma = avc->anon_vma;
405
406 put_anon_vma(anon_vma);
407
Rik van Riel5beb4932010-03-05 13:42:07 -0800408 list_del(&avc->same_vma);
409 anon_vma_chain_free(avc);
410 }
411}
412
Alexey Dobriyan51cc5062008-07-25 19:45:34 -0700413static void anon_vma_ctor(void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700414{
Christoph Lametera35afb82007-05-16 22:10:57 -0700415 struct anon_vma *anon_vma = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700416
Peter Zijlstra2b575eb2011-05-24 17:12:11 -0700417 mutex_init(&anon_vma->mutex);
Peter Zijlstra83813262011-03-22 16:32:48 -0700418 atomic_set(&anon_vma->refcount, 0);
Christoph Lametera35afb82007-05-16 22:10:57 -0700419 INIT_LIST_HEAD(&anon_vma->head);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700420}
421
422void __init anon_vma_init(void)
423{
424 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
Paul Mundt20c2df82007-07-20 10:11:58 +0900425 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
Rik van Riel5beb4932010-03-05 13:42:07 -0800426 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427}
428
429/*
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700430 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
431 *
432 * Since there is no serialization what so ever against page_remove_rmap()
433 * the best this function can do is return a locked anon_vma that might
434 * have been relevant to this page.
435 *
436 * The page might have been remapped to a different anon_vma or the anon_vma
437 * returned may already be freed (and even reused).
438 *
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200439 * In case it was remapped to a different anon_vma, the new anon_vma will be a
440 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
441 * ensure that any anon_vma obtained from the page will still be valid for as
442 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
443 *
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700444 * All users of this function must be very careful when walking the anon_vma
445 * chain and verify that the page in question is indeed mapped in it
446 * [ something equivalent to page_mapped_in_vma() ].
447 *
448 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
449 * that the anon_vma pointer from page->mapping is valid if there is a
450 * mapcount, we can dereference the anon_vma after observing those.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700451 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700452struct anon_vma *page_get_anon_vma(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700453{
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700454 struct anon_vma *anon_vma = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700455 unsigned long anon_mapping;
456
457 rcu_read_lock();
Hugh Dickins80e14822009-12-14 17:59:29 -0800458 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800459 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 goto out;
461 if (!page_mapped(page))
462 goto out;
463
464 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700465 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
466 anon_vma = NULL;
467 goto out;
468 }
Hugh Dickinsf1819422010-08-25 23:12:54 -0700469
470 /*
471 * If this page is still mapped, then its anon_vma cannot have been
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700472 * freed. But if it has been unmapped, we have no security against the
473 * anon_vma structure being freed and reused (for another anon_vma:
474 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
475 * above cannot corrupt).
Hugh Dickinsf1819422010-08-25 23:12:54 -0700476 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700477 if (!page_mapped(page)) {
478 put_anon_vma(anon_vma);
479 anon_vma = NULL;
480 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700481out:
482 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700483
484 return anon_vma;
485}
486
Peter Zijlstra88c22082011-05-24 17:12:13 -0700487/*
488 * Similar to page_get_anon_vma() except it locks the anon_vma.
489 *
490 * Its a little more complex as it tries to keep the fast path to a single
491 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
492 * reference like with page_get_anon_vma() and then block on the mutex.
493 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700494struct anon_vma *page_lock_anon_vma(struct page *page)
495{
Peter Zijlstra88c22082011-05-24 17:12:13 -0700496 struct anon_vma *anon_vma = NULL;
Hugh Dickinseee0f252011-05-28 13:20:21 -0700497 struct anon_vma *root_anon_vma;
Peter Zijlstra88c22082011-05-24 17:12:13 -0700498 unsigned long anon_mapping;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700499
Peter Zijlstra88c22082011-05-24 17:12:13 -0700500 rcu_read_lock();
501 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
502 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
503 goto out;
504 if (!page_mapped(page))
505 goto out;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700506
Peter Zijlstra88c22082011-05-24 17:12:13 -0700507 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Hugh Dickinseee0f252011-05-28 13:20:21 -0700508 root_anon_vma = ACCESS_ONCE(anon_vma->root);
509 if (mutex_trylock(&root_anon_vma->mutex)) {
Peter Zijlstra88c22082011-05-24 17:12:13 -0700510 /*
Hugh Dickinseee0f252011-05-28 13:20:21 -0700511 * If the page is still mapped, then this anon_vma is still
512 * its anon_vma, and holding the mutex ensures that it will
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200513 * not go away, see anon_vma_free().
Peter Zijlstra88c22082011-05-24 17:12:13 -0700514 */
Hugh Dickinseee0f252011-05-28 13:20:21 -0700515 if (!page_mapped(page)) {
516 mutex_unlock(&root_anon_vma->mutex);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700517 anon_vma = NULL;
518 }
519 goto out;
520 }
521
522 /* trylock failed, we got to sleep */
523 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
524 anon_vma = NULL;
525 goto out;
526 }
527
528 if (!page_mapped(page)) {
529 put_anon_vma(anon_vma);
530 anon_vma = NULL;
531 goto out;
532 }
533
534 /* we pinned the anon_vma, its safe to sleep */
535 rcu_read_unlock();
536 anon_vma_lock(anon_vma);
537
538 if (atomic_dec_and_test(&anon_vma->refcount)) {
539 /*
540 * Oops, we held the last refcount, release the lock
541 * and bail -- can't simply use put_anon_vma() because
542 * we'll deadlock on the anon_vma_lock() recursion.
543 */
544 anon_vma_unlock(anon_vma);
545 __put_anon_vma(anon_vma);
546 anon_vma = NULL;
547 }
548
549 return anon_vma;
550
551out:
552 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700553 return anon_vma;
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800554}
555
Andi Kleen10be22d2009-09-16 11:50:04 +0200556void page_unlock_anon_vma(struct anon_vma *anon_vma)
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800557{
Rik van Rielcba48b92010-08-09 17:18:38 -0700558 anon_vma_unlock(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700559}
560
561/*
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800562 * At what user virtual address is page expected in @vma?
563 * Returns virtual address or -EFAULT if page's index/offset is not
564 * within the range mapped the @vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700565 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800566inline unsigned long
Linus Torvalds1da177e2005-04-16 15:20:36 -0700567vma_address(struct page *page, struct vm_area_struct *vma)
568{
569 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
570 unsigned long address;
571
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900572 if (unlikely(is_vm_hugetlb_page(vma)))
573 pgoff = page->index << huge_page_order(page_hstate(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700574 address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
575 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
Lee Schermerhorn3ad33b22007-11-14 16:59:10 -0800576 /* page should be within @vma mapping range */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700577 return -EFAULT;
578 }
579 return address;
580}
581
582/*
Huang Shijiebf89c8c2009-10-01 15:44:04 -0700583 * At what user virtual address is page expected in vma?
Naoya Horiguchiab941e02010-05-11 14:06:55 -0700584 * Caller should check the page is actually part of the vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585 */
586unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
587{
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700588 if (PageAnon(page)) {
Hugh Dickins4829b902010-10-02 17:46:06 -0700589 struct anon_vma *page__anon_vma = page_anon_vma(page);
590 /*
591 * Note: swapoff's unuse_vma() is more efficient with this
592 * check, and needs it to match anon_vma when KSM is active.
593 */
594 if (!vma->anon_vma || !page__anon_vma ||
595 vma->anon_vma->root != page__anon_vma->root)
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700596 return -EFAULT;
597 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
Hugh Dickinsee498ed2005-11-21 21:32:18 -0800598 if (!vma->vm_file ||
599 vma->vm_file->f_mapping != page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700600 return -EFAULT;
601 } else
602 return -EFAULT;
603 return vma_address(page, vma);
604}
605
606/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700607 * Check that @page is mapped at @address into @mm.
608 *
Nick Piggin479db0b2008-08-20 14:09:18 -0700609 * If @sync is false, page_check_address may perform a racy check to avoid
610 * the page table lock when the pte is not present (helpful when reclaiming
611 * highly shared pages).
612 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700613 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700614 */
Namhyung Kime9a81a82010-10-26 14:22:01 -0700615pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
Nick Piggin479db0b2008-08-20 14:09:18 -0700616 unsigned long address, spinlock_t **ptlp, int sync)
Nikita Danilov81b40822005-05-01 08:58:36 -0700617{
618 pgd_t *pgd;
619 pud_t *pud;
620 pmd_t *pmd;
621 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700622 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700623
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900624 if (unlikely(PageHuge(page))) {
625 pte = huge_pte_offset(mm, address);
626 ptl = &mm->page_table_lock;
627 goto check;
628 }
629
Nikita Danilov81b40822005-05-01 08:58:36 -0700630 pgd = pgd_offset(mm, address);
Hugh Dickinsc0718802005-10-29 18:16:31 -0700631 if (!pgd_present(*pgd))
632 return NULL;
633
634 pud = pud_offset(pgd, address);
635 if (!pud_present(*pud))
636 return NULL;
637
638 pmd = pmd_offset(pud, address);
639 if (!pmd_present(*pmd))
640 return NULL;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800641 if (pmd_trans_huge(*pmd))
642 return NULL;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700643
644 pte = pte_offset_map(pmd, address);
645 /* Make a quick check before getting the lock */
Nick Piggin479db0b2008-08-20 14:09:18 -0700646 if (!sync && !pte_present(*pte)) {
Hugh Dickinsc0718802005-10-29 18:16:31 -0700647 pte_unmap(pte);
648 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700649 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700650
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700651 ptl = pte_lockptr(mm, pmd);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900652check:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700653 spin_lock(ptl);
654 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
655 *ptlp = ptl;
656 return pte;
657 }
658 pte_unmap_unlock(pte, ptl);
659 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700660}
661
Nick Pigginb291f002008-10-18 20:26:44 -0700662/**
663 * page_mapped_in_vma - check whether a page is really mapped in a VMA
664 * @page: the page to test
665 * @vma: the VMA to test
666 *
667 * Returns 1 if the page is mapped into the page tables of the VMA, 0
668 * if the page is not mapped into the page tables of this VMA. Only
669 * valid for normal file or anonymous VMAs.
670 */
Andi Kleen6a460792009-09-16 11:50:15 +0200671int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
Nick Pigginb291f002008-10-18 20:26:44 -0700672{
673 unsigned long address;
674 pte_t *pte;
675 spinlock_t *ptl;
676
677 address = vma_address(page, vma);
678 if (address == -EFAULT) /* out of vma range */
679 return 0;
680 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
681 if (!pte) /* the page is not in this mm */
682 return 0;
683 pte_unmap_unlock(pte, ptl);
684
685 return 1;
686}
687
Nikita Danilov81b40822005-05-01 08:58:36 -0700688/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700689 * Subfunctions of page_referenced: page_referenced_one called
690 * repeatedly from either page_referenced_anon or page_referenced_file.
691 */
Hugh Dickins5ad64682009-12-14 17:59:24 -0800692int page_referenced_one(struct page *page, struct vm_area_struct *vma,
693 unsigned long address, unsigned int *mapcount,
694 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700695{
696 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697 int referenced = 0;
698
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800699 if (unlikely(PageTransHuge(page))) {
700 pmd_t *pmd;
701
702 spin_lock(&mm->page_table_lock);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800703 /*
704 * rmap might return false positives; we must filter
705 * these out using page_check_address_pmd().
706 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800707 pmd = page_check_address_pmd(page, mm, address,
708 PAGE_CHECK_ADDRESS_PMD_FLAG);
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800709 if (!pmd) {
710 spin_unlock(&mm->page_table_lock);
711 goto out;
712 }
713
714 if (vma->vm_flags & VM_LOCKED) {
715 spin_unlock(&mm->page_table_lock);
716 *mapcount = 0; /* break early from loop */
717 *vm_flags |= VM_LOCKED;
718 goto out;
719 }
720
721 /* go ahead even if the pmd is pmd_trans_splitting() */
722 if (pmdp_clear_flush_young_notify(vma, address, pmd))
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800723 referenced++;
724 spin_unlock(&mm->page_table_lock);
725 } else {
726 pte_t *pte;
727 spinlock_t *ptl;
728
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800729 /*
730 * rmap might return false positives; we must filter
731 * these out using page_check_address().
732 */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800733 pte = page_check_address(page, mm, address, &ptl, 0);
734 if (!pte)
735 goto out;
736
Andrea Arcangeli2da28bf2011-03-11 14:58:29 -0800737 if (vma->vm_flags & VM_LOCKED) {
738 pte_unmap_unlock(pte, ptl);
739 *mapcount = 0; /* break early from loop */
740 *vm_flags |= VM_LOCKED;
741 goto out;
742 }
743
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800744 if (ptep_clear_flush_young_notify(vma, address, pte)) {
745 /*
746 * Don't treat a reference through a sequentially read
747 * mapping as such. If the page has been used in
748 * another mapping, we will catch it; if this other
749 * mapping is already gone, the unmap path will have
750 * set PG_referenced or activated the page.
751 */
752 if (likely(!VM_SequentialReadHint(vma)))
753 referenced++;
754 }
755 pte_unmap_unlock(pte, ptl);
756 }
757
Hugh Dickinsc0718802005-10-29 18:16:31 -0700758 (*mapcount)--;
Huang Shijie273f0472009-12-14 17:58:51 -0800759
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700760 if (referenced)
761 *vm_flags |= vma->vm_flags;
Huang Shijie273f0472009-12-14 17:58:51 -0800762out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763 return referenced;
764}
765
Balbir Singhbed71612008-02-07 00:14:01 -0800766static int page_referenced_anon(struct page *page,
Johannes Weiner72835c82012-01-12 17:18:32 -0800767 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700768 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700769{
770 unsigned int mapcount;
771 struct anon_vma *anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800772 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700773 int referenced = 0;
774
775 anon_vma = page_lock_anon_vma(page);
776 if (!anon_vma)
777 return referenced;
778
779 mapcount = page_mapcount(page);
Rik van Riel5beb4932010-03-05 13:42:07 -0800780 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
781 struct vm_area_struct *vma = avc->vma;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800782 unsigned long address = vma_address(page, vma);
783 if (address == -EFAULT)
784 continue;
Balbir Singhbed71612008-02-07 00:14:01 -0800785 /*
786 * If we are reclaiming on behalf of a cgroup, skip
787 * counting on behalf of references from different
788 * cgroups
789 */
Johannes Weiner72835c82012-01-12 17:18:32 -0800790 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
Balbir Singhbed71612008-02-07 00:14:01 -0800791 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800792 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700793 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700794 if (!mapcount)
795 break;
796 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800797
798 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700799 return referenced;
800}
801
802/**
803 * page_referenced_file - referenced check for object-based rmap
804 * @page: the page we're checking references on.
Johannes Weiner72835c82012-01-12 17:18:32 -0800805 * @memcg: target memory control group
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700806 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700807 *
808 * For an object-based mapped page, find all the places it is mapped and
809 * check/clear the referenced flag. This is done by following the page->mapping
810 * pointer, then walking the chain of vmas it holds. It returns the number
811 * of references it found.
812 *
813 * This function is only called from page_referenced for object-based pages.
814 */
Balbir Singhbed71612008-02-07 00:14:01 -0800815static int page_referenced_file(struct page *page,
Johannes Weiner72835c82012-01-12 17:18:32 -0800816 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700817 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818{
819 unsigned int mapcount;
820 struct address_space *mapping = page->mapping;
821 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
822 struct vm_area_struct *vma;
823 struct prio_tree_iter iter;
824 int referenced = 0;
825
826 /*
827 * The caller's checks on page->mapping and !PageAnon have made
828 * sure that this is a file page: the check for page->mapping
829 * excludes the case just before it gets set on an anon page.
830 */
831 BUG_ON(PageAnon(page));
832
833 /*
834 * The page lock not only makes sure that page->mapping cannot
835 * suddenly be NULLified by truncation, it makes sure that the
836 * structure at mapping cannot be freed and reused yet,
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700837 * so we can safely take mapping->i_mmap_mutex.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700838 */
839 BUG_ON(!PageLocked(page));
840
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700841 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700842
843 /*
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700844 * i_mmap_mutex does not stabilize mapcount at all, but mapcount
Linus Torvalds1da177e2005-04-16 15:20:36 -0700845 * is more likely to be accurate if we note it after spinning.
846 */
847 mapcount = page_mapcount(page);
848
849 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800850 unsigned long address = vma_address(page, vma);
851 if (address == -EFAULT)
852 continue;
Balbir Singhbed71612008-02-07 00:14:01 -0800853 /*
854 * If we are reclaiming on behalf of a cgroup, skip
855 * counting on behalf of references from different
856 * cgroups
857 */
Johannes Weiner72835c82012-01-12 17:18:32 -0800858 if (memcg && !mm_match_cgroup(vma->vm_mm, memcg))
Balbir Singhbed71612008-02-07 00:14:01 -0800859 continue;
Hugh Dickins1cb17292009-12-14 17:59:01 -0800860 referenced += page_referenced_one(page, vma, address,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700861 &mapcount, vm_flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700862 if (!mapcount)
863 break;
864 }
865
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700866 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700867 return referenced;
868}
869
870/**
871 * page_referenced - test if the page was referenced
872 * @page: the page to test
873 * @is_locked: caller holds lock on the page
Johannes Weiner72835c82012-01-12 17:18:32 -0800874 * @memcg: target memory cgroup
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700875 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700876 *
877 * Quick test_and_clear_referenced for all mappings to a page,
878 * returns the number of ptes which referenced the page.
879 */
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700880int page_referenced(struct page *page,
881 int is_locked,
Johannes Weiner72835c82012-01-12 17:18:32 -0800882 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700883 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700884{
885 int referenced = 0;
Hugh Dickins5ad64682009-12-14 17:59:24 -0800886 int we_locked = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700887
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700888 *vm_flags = 0;
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800889 if (page_mapped(page) && page_rmapping(page)) {
Hugh Dickins5ad64682009-12-14 17:59:24 -0800890 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
891 we_locked = trylock_page(page);
892 if (!we_locked) {
893 referenced++;
894 goto out;
895 }
896 }
897 if (unlikely(PageKsm(page)))
Johannes Weiner72835c82012-01-12 17:18:32 -0800898 referenced += page_referenced_ksm(page, memcg,
Hugh Dickins5ad64682009-12-14 17:59:24 -0800899 vm_flags);
900 else if (PageAnon(page))
Johannes Weiner72835c82012-01-12 17:18:32 -0800901 referenced += page_referenced_anon(page, memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700902 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800903 else if (page->mapping)
Johannes Weiner72835c82012-01-12 17:18:32 -0800904 referenced += page_referenced_file(page, memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700905 vm_flags);
Hugh Dickins5ad64682009-12-14 17:59:24 -0800906 if (we_locked)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700907 unlock_page(page);
Martin Schwidefsky50a15982011-07-24 10:47:59 +0200908
909 if (page_test_and_clear_young(page_to_pfn(page)))
910 referenced++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700911 }
Hugh Dickins5ad64682009-12-14 17:59:24 -0800912out:
Linus Torvalds1da177e2005-04-16 15:20:36 -0700913 return referenced;
914}
915
Hugh Dickins1cb17292009-12-14 17:59:01 -0800916static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
917 unsigned long address)
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700918{
919 struct mm_struct *mm = vma->vm_mm;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100920 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700921 spinlock_t *ptl;
922 int ret = 0;
923
Nick Piggin479db0b2008-08-20 14:09:18 -0700924 pte = page_check_address(page, mm, address, &ptl, 1);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700925 if (!pte)
926 goto out;
927
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100928 if (pte_dirty(*pte) || pte_write(*pte)) {
929 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700930
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100931 flush_cache_page(vma, address, pte_pfn(*pte));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -0700932 entry = ptep_clear_flush_notify(vma, address, pte);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100933 entry = pte_wrprotect(entry);
934 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -0800935 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +0100936 ret = 1;
937 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700938
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700939 pte_unmap_unlock(pte, ptl);
940out:
941 return ret;
942}
943
944static int page_mkclean_file(struct address_space *mapping, struct page *page)
945{
946 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
947 struct vm_area_struct *vma;
948 struct prio_tree_iter iter;
949 int ret = 0;
950
951 BUG_ON(PageAnon(page));
952
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700953 mutex_lock(&mapping->i_mmap_mutex);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700954 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -0800955 if (vma->vm_flags & VM_SHARED) {
956 unsigned long address = vma_address(page, vma);
957 if (address == -EFAULT)
958 continue;
959 ret += page_mkclean_one(page, vma, address);
960 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700961 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -0700962 mutex_unlock(&mapping->i_mmap_mutex);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700963 return ret;
964}
965
966int page_mkclean(struct page *page)
967{
968 int ret = 0;
969
970 BUG_ON(!PageLocked(page));
971
972 if (page_mapped(page)) {
973 struct address_space *mapping = page_mapping(page);
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100974 if (mapping) {
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700975 ret = page_mkclean_file(mapping, page);
Martin Schwidefsky2d425522011-05-23 10:24:39 +0200976 if (page_test_and_clear_dirty(page_to_pfn(page), 1))
Christian Borntraegerce7e9fa2007-11-20 11:13:36 +0100977 ret = 1;
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200978 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700979 }
980
981 return ret;
982}
Jaya Kumar60b59be2007-05-08 00:37:37 -0700983EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -0700984
Linus Torvalds1da177e2005-04-16 15:20:36 -0700985/**
Rik van Rielc44b6742010-03-05 13:42:09 -0800986 * page_move_anon_rmap - move a page to our anon_vma
987 * @page: the page to move to our anon_vma
988 * @vma: the vma the page belongs to
989 * @address: the user virtual address mapped
990 *
991 * When a page belongs exclusively to one process after a COW event,
992 * that page can be moved into the anon_vma that belongs to just that
993 * process, so the rmap code will not search the parent or sibling
994 * processes.
995 */
996void page_move_anon_rmap(struct page *page,
997 struct vm_area_struct *vma, unsigned long address)
998{
999 struct anon_vma *anon_vma = vma->anon_vma;
1000
1001 VM_BUG_ON(!PageLocked(page));
1002 VM_BUG_ON(!anon_vma);
1003 VM_BUG_ON(page->index != linear_page_index(vma, address));
1004
1005 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1006 page->mapping = (struct address_space *) anon_vma;
1007}
1008
1009/**
Andi Kleen4e1c1972010-09-22 12:43:56 +02001010 * __page_set_anon_rmap - set up new anonymous rmap
1011 * @page: Page to add to rmap
1012 * @vma: VM area to add page to.
1013 * @address: User virtual address of the mapping
Rik van Riele8a03fe2010-04-14 17:59:28 -04001014 * @exclusive: the page is exclusively owned by the current process
Nick Piggin9617d952006-01-06 00:11:12 -08001015 */
1016static void __page_set_anon_rmap(struct page *page,
Rik van Riele8a03fe2010-04-14 17:59:28 -04001017 struct vm_area_struct *vma, unsigned long address, int exclusive)
Nick Piggin9617d952006-01-06 00:11:12 -08001018{
Rik van Riele8a03fe2010-04-14 17:59:28 -04001019 struct anon_vma *anon_vma = vma->anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -08001020
Rik van Riele8a03fe2010-04-14 17:59:28 -04001021 BUG_ON(!anon_vma);
Linus Torvaldsea900022010-04-12 12:44:29 -07001022
Andi Kleen4e1c1972010-09-22 12:43:56 +02001023 if (PageAnon(page))
1024 return;
1025
Linus Torvaldsea900022010-04-12 12:44:29 -07001026 /*
Rik van Riele8a03fe2010-04-14 17:59:28 -04001027 * If the page isn't exclusively mapped into this vma,
1028 * we must use the _oldest_ possible anon_vma for the
1029 * page mapping!
Linus Torvaldsea900022010-04-12 12:44:29 -07001030 */
Andi Kleen4e1c1972010-09-22 12:43:56 +02001031 if (!exclusive)
Andrea Arcangeli288468c2010-08-09 17:19:09 -07001032 anon_vma = anon_vma->root;
Linus Torvaldsea900022010-04-12 12:44:29 -07001033
Nick Piggin9617d952006-01-06 00:11:12 -08001034 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1035 page->mapping = (struct address_space *) anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -08001036 page->index = linear_page_index(vma, address);
Nick Piggin9617d952006-01-06 00:11:12 -08001037}
1038
1039/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001040 * __page_check_anon_rmap - sanity check anonymous rmap addition
Nick Pigginc97a9e12007-05-16 22:11:21 -07001041 * @page: the page to add the mapping to
1042 * @vma: the vm area in which the mapping is added
1043 * @address: the user virtual address mapped
1044 */
1045static void __page_check_anon_rmap(struct page *page,
1046 struct vm_area_struct *vma, unsigned long address)
1047{
1048#ifdef CONFIG_DEBUG_VM
1049 /*
1050 * The page's anon-rmap details (mapping and index) are guaranteed to
1051 * be set up correctly at this point.
1052 *
1053 * We have exclusion against page_add_anon_rmap because the caller
1054 * always holds the page locked, except if called from page_dup_rmap,
1055 * in which case the page is already known to be setup.
1056 *
1057 * We have exclusion against page_add_new_anon_rmap because those pages
1058 * are initially only visible via the pagetables, and the pte is locked
1059 * over the call to page_add_new_anon_rmap.
1060 */
Andrea Arcangeli44ab57a2010-08-09 17:19:10 -07001061 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
Nick Pigginc97a9e12007-05-16 22:11:21 -07001062 BUG_ON(page->index != linear_page_index(vma, address));
1063#endif
1064}
1065
1066/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001067 * page_add_anon_rmap - add pte mapping to an anonymous page
1068 * @page: the page to add the mapping to
1069 * @vma: the vm area in which the mapping is added
1070 * @address: the user virtual address mapped
1071 *
Hugh Dickins5ad64682009-12-14 17:59:24 -08001072 * The caller needs to hold the pte lock, and the page must be locked in
Hugh Dickins80e14822009-12-14 17:59:29 -08001073 * the anon_vma case: to serialize mapping,index checking after setting,
1074 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1075 * (but PageKsm is never downgraded to PageAnon).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001076 */
1077void page_add_anon_rmap(struct page *page,
1078 struct vm_area_struct *vma, unsigned long address)
1079{
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001080 do_page_add_anon_rmap(page, vma, address, 0);
1081}
1082
1083/*
1084 * Special version of the above for do_swap_page, which often runs
1085 * into pages that are exclusively owned by the current process.
1086 * Everybody else should continue to use page_add_anon_rmap above.
1087 */
1088void do_page_add_anon_rmap(struct page *page,
1089 struct vm_area_struct *vma, unsigned long address, int exclusive)
1090{
Hugh Dickins5ad64682009-12-14 17:59:24 -08001091 int first = atomic_inc_and_test(&page->_mapcount);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001092 if (first) {
1093 if (!PageTransHuge(page))
1094 __inc_zone_page_state(page, NR_ANON_PAGES);
1095 else
1096 __inc_zone_page_state(page,
1097 NR_ANON_TRANSPARENT_HUGEPAGES);
1098 }
Hugh Dickins5ad64682009-12-14 17:59:24 -08001099 if (unlikely(PageKsm(page)))
1100 return;
1101
Nick Pigginc97a9e12007-05-16 22:11:21 -07001102 VM_BUG_ON(!PageLocked(page));
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001103 /* address might be in next vma when migration races vma_adjust */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001104 if (first)
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001105 __page_set_anon_rmap(page, vma, address, exclusive);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001106 else
Nick Pigginc97a9e12007-05-16 22:11:21 -07001107 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001108}
1109
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001110/**
Nick Piggin9617d952006-01-06 00:11:12 -08001111 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1112 * @page: the page to add the mapping to
1113 * @vma: the vm area in which the mapping is added
1114 * @address: the user virtual address mapped
1115 *
1116 * Same as page_add_anon_rmap but must only be called on *new* pages.
1117 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -07001118 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -08001119 */
1120void page_add_new_anon_rmap(struct page *page,
1121 struct vm_area_struct *vma, unsigned long address)
1122{
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001123 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001124 SetPageSwapBacked(page);
1125 atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
Andrea Arcangeli79134172011-01-13 15:46:58 -08001126 if (!PageTransHuge(page))
1127 __inc_zone_page_state(page, NR_ANON_PAGES);
1128 else
1129 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
Rik van Riele8a03fe2010-04-14 17:59:28 -04001130 __page_set_anon_rmap(page, vma, address, 1);
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001131 if (page_evictable(page, vma))
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001132 lru_cache_add_lru(page, LRU_ACTIVE_ANON);
Hugh Dickinsb5934c52009-01-06 14:39:25 -08001133 else
1134 add_page_to_unevictable_list(page);
Nick Piggin9617d952006-01-06 00:11:12 -08001135}
1136
Linus Torvalds1da177e2005-04-16 15:20:36 -07001137/**
1138 * page_add_file_rmap - add pte mapping to a file page
1139 * @page: the page to add the mapping to
1140 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001141 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001142 */
1143void page_add_file_rmap(struct page *page)
1144{
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001145 bool locked;
1146 unsigned long flags;
1147
1148 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
Balbir Singhd69b0422009-06-17 16:26:34 -07001149 if (atomic_inc_and_test(&page->_mapcount)) {
Christoph Lameter65ba55f2006-06-30 01:55:34 -07001150 __inc_zone_page_state(page, NR_FILE_MAPPED);
Greg Thelen2a7106f2011-01-13 15:47:37 -08001151 mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED);
Balbir Singhd69b0422009-06-17 16:26:34 -07001152 }
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001153 mem_cgroup_end_update_page_stat(page, &locked, &flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001154}
1155
1156/**
1157 * page_remove_rmap - take down pte mapping from a page
1158 * @page: page to remove mapping from
1159 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001160 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001161 */
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001162void page_remove_rmap(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001163{
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001164 bool anon = PageAnon(page);
1165 bool locked;
1166 unsigned long flags;
1167
1168 /*
1169 * The anon case has no mem_cgroup page_stat to update; but may
1170 * uncharge_page() below, where the lock ordering can deadlock if
1171 * we hold the lock against page_stat move: so avoid it on anon.
1172 */
1173 if (!anon)
1174 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
1175
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001176 /* page still mapped by someone else? */
1177 if (!atomic_add_negative(-1, &page->_mapcount))
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001178 goto out;
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001179
1180 /*
1181 * Now that the last pte has gone, s390 must transfer dirty
1182 * flag from storage key to struct page. We can usually skip
1183 * this if the page is anon, so about to be freed; but perhaps
1184 * not if it's in swapcache - there might be another pte slot
1185 * containing the swap entry, but page not yet written to swap.
1186 */
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001187 if ((!anon || PageSwapCache(page)) &&
Martin Schwidefsky2d425522011-05-23 10:24:39 +02001188 page_test_and_clear_dirty(page_to_pfn(page), 1))
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001189 set_page_dirty(page);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001190 /*
1191 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
1192 * and not charged by memcg for now.
1193 */
1194 if (unlikely(PageHuge(page)))
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001195 goto out;
1196 if (anon) {
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001197 mem_cgroup_uncharge_page(page);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001198 if (!PageTransHuge(page))
1199 __dec_zone_page_state(page, NR_ANON_PAGES);
1200 else
1201 __dec_zone_page_state(page,
1202 NR_ANON_TRANSPARENT_HUGEPAGES);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001203 } else {
1204 __dec_zone_page_state(page, NR_FILE_MAPPED);
Greg Thelen2a7106f2011-01-13 15:47:37 -08001205 mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED);
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001206 }
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001207 /*
1208 * It would be tidy to reset the PageAnon mapping here,
1209 * but that might overwrite a racing page_add_anon_rmap
1210 * which increments mapcount after us but sets mapping
1211 * before us: so leave the reset to free_hot_cold_page,
1212 * and remember that it's only reliable while mapped.
1213 * Leaving it set also helps swapoff to reinstate ptes
1214 * faster for those pages still in swapcache.
1215 */
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001216out:
1217 if (!anon)
1218 mem_cgroup_end_update_page_stat(page, &locked, &flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001219}
1220
1221/*
1222 * Subfunctions of try_to_unmap: try_to_unmap_one called
Wanlong Gao99ef0312011-10-31 17:08:51 -07001223 * repeatedly from try_to_unmap_ksm, try_to_unmap_anon or try_to_unmap_file.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001224 */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001225int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1226 unsigned long address, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001227{
1228 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001229 pte_t *pte;
1230 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001231 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001232 int ret = SWAP_AGAIN;
1233
Nick Piggin479db0b2008-08-20 14:09:18 -07001234 pte = page_check_address(page, mm, address, &ptl, 0);
Hugh Dickinsc0718802005-10-29 18:16:31 -07001235 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -07001236 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001237
1238 /*
1239 * If the page is mlock()d, we cannot swap it out.
1240 * If it's recently referenced (perhaps page_referenced
1241 * skipped over this mm) then we should reactivate it.
1242 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001243 if (!(flags & TTU_IGNORE_MLOCK)) {
KOSAKI Motohirocaed0f42009-12-14 17:59:45 -08001244 if (vma->vm_flags & VM_LOCKED)
1245 goto out_mlock;
1246
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001247 if (TTU_ACTION(flags) == TTU_MUNLOCK)
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001248 goto out_unmap;
Andi Kleen14fa31b2009-09-16 11:50:10 +02001249 }
1250 if (!(flags & TTU_IGNORE_ACCESS)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001251 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1252 ret = SWAP_FAIL;
1253 goto out_unmap;
1254 }
1255 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001256
Linus Torvalds1da177e2005-04-16 15:20:36 -07001257 /* Nuke the page table entry. */
1258 flush_cache_page(vma, address, page_to_pfn(page));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001259 pteval = ptep_clear_flush_notify(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001260
1261 /* Move the dirty bit to the physical page now the pte is gone. */
1262 if (pte_dirty(pteval))
1263 set_page_dirty(page);
1264
Hugh Dickins365e9c872005-10-29 18:16:18 -07001265 /* Update high watermark before we lower rss */
1266 update_hiwater_rss(mm);
1267
Andi Kleen888b9f72009-09-16 11:50:11 +02001268 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
1269 if (PageAnon(page))
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001270 dec_mm_counter(mm, MM_ANONPAGES);
Andi Kleen888b9f72009-09-16 11:50:11 +02001271 else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001272 dec_mm_counter(mm, MM_FILEPAGES);
Andi Kleen888b9f72009-09-16 11:50:11 +02001273 set_pte_at(mm, address, pte,
1274 swp_entry_to_pte(make_hwpoison_entry(page)));
1275 } else if (PageAnon(page)) {
Hugh Dickins4c21e2f2005-10-29 18:16:40 -07001276 swp_entry_t entry = { .val = page_private(page) };
Christoph Lameter06972122006-06-23 02:03:35 -07001277
1278 if (PageSwapCache(page)) {
1279 /*
1280 * Store the swap location in the pte.
1281 * See handle_pte_fault() ...
1282 */
Hugh Dickins570a3352009-12-14 17:58:46 -08001283 if (swap_duplicate(entry) < 0) {
1284 set_pte_at(mm, address, pte, pteval);
1285 ret = SWAP_FAIL;
1286 goto out_unmap;
1287 }
Christoph Lameter06972122006-06-23 02:03:35 -07001288 if (list_empty(&mm->mmlist)) {
1289 spin_lock(&mmlist_lock);
1290 if (list_empty(&mm->mmlist))
1291 list_add(&mm->mmlist, &init_mm.mmlist);
1292 spin_unlock(&mmlist_lock);
1293 }
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001294 dec_mm_counter(mm, MM_ANONPAGES);
KAMEZAWA Hiroyukib084d432010-03-05 13:41:42 -08001295 inc_mm_counter(mm, MM_SWAPENTS);
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001296 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
Christoph Lameter06972122006-06-23 02:03:35 -07001297 /*
1298 * Store the pfn of the page in a special migration
1299 * pte. do_swap_page() will wait until the migration
1300 * pte is removed and then restart fault handling.
1301 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001302 BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION);
Christoph Lameter06972122006-06-23 02:03:35 -07001303 entry = make_migration_entry(page, pte_write(pteval));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001304 }
1305 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1306 BUG_ON(pte_file(*pte));
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001307 } else if (IS_ENABLED(CONFIG_MIGRATION) &&
1308 (TTU_ACTION(flags) == TTU_MIGRATION)) {
Christoph Lameter04e62a22006-06-23 02:03:38 -07001309 /* Establish migration entry for a file page */
1310 swp_entry_t entry;
1311 entry = make_migration_entry(page, pte_write(pteval));
1312 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1313 } else
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001314 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001315
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001316 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001317 page_cache_release(page);
1318
1319out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -07001320 pte_unmap_unlock(pte, ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001321out:
1322 return ret;
KOSAKI Motohirocaed0f42009-12-14 17:59:45 -08001323
1324out_mlock:
1325 pte_unmap_unlock(pte, ptl);
1326
1327
1328 /*
1329 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
1330 * unstable result and race. Plus, We can't wait here because
Peter Zijlstra2b575eb2011-05-24 17:12:11 -07001331 * we now hold anon_vma->mutex or mapping->i_mmap_mutex.
KOSAKI Motohirocaed0f42009-12-14 17:59:45 -08001332 * if trylock failed, the page remain in evictable lru and later
1333 * vmscan could retry to move the page to unevictable lru if the
1334 * page is actually mlocked.
1335 */
1336 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
1337 if (vma->vm_flags & VM_LOCKED) {
1338 mlock_vma_page(page);
1339 ret = SWAP_MLOCK;
1340 }
1341 up_read(&vma->vm_mm->mmap_sem);
1342 }
1343 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001344}
1345
1346/*
1347 * objrmap doesn't work for nonlinear VMAs because the assumption that
1348 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
1349 * Consequently, given a particular page and its ->index, we cannot locate the
1350 * ptes which are mapping that page without an exhaustive linear search.
1351 *
1352 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
1353 * maps the file to which the target page belongs. The ->vm_private_data field
1354 * holds the current cursor into that scan. Successive searches will circulate
1355 * around the vma's virtual address space.
1356 *
1357 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
1358 * more scanning pressure is placed against them as well. Eventually pages
1359 * will become fully unmapped and are eligible for eviction.
1360 *
1361 * For very sparsely populated VMAs this is a little inefficient - chances are
1362 * there there won't be many ptes located within the scan cluster. In this case
1363 * maybe we could scan further - to the end of the pte page, perhaps.
Nick Pigginb291f002008-10-18 20:26:44 -07001364 *
1365 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
1366 * acquire it without blocking. If vma locked, mlock the pages in the cluster,
1367 * rather than unmapping them. If we encounter the "check_page" that vmscan is
1368 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 */
1370#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
1371#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
1372
Nick Pigginb291f002008-10-18 20:26:44 -07001373static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
1374 struct vm_area_struct *vma, struct page *check_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001375{
1376 struct mm_struct *mm = vma->vm_mm;
1377 pgd_t *pgd;
1378 pud_t *pud;
1379 pmd_t *pmd;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001380 pte_t *pte;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001381 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001382 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001383 struct page *page;
1384 unsigned long address;
1385 unsigned long end;
Nick Pigginb291f002008-10-18 20:26:44 -07001386 int ret = SWAP_AGAIN;
1387 int locked_vma = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001388
Linus Torvalds1da177e2005-04-16 15:20:36 -07001389 address = (vma->vm_start + cursor) & CLUSTER_MASK;
1390 end = address + CLUSTER_SIZE;
1391 if (address < vma->vm_start)
1392 address = vma->vm_start;
1393 if (end > vma->vm_end)
1394 end = vma->vm_end;
1395
1396 pgd = pgd_offset(mm, address);
1397 if (!pgd_present(*pgd))
Nick Pigginb291f002008-10-18 20:26:44 -07001398 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001399
1400 pud = pud_offset(pgd, address);
1401 if (!pud_present(*pud))
Nick Pigginb291f002008-10-18 20:26:44 -07001402 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001403
1404 pmd = pmd_offset(pud, address);
1405 if (!pmd_present(*pmd))
Nick Pigginb291f002008-10-18 20:26:44 -07001406 return ret;
1407
1408 /*
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001409 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
Nick Pigginb291f002008-10-18 20:26:44 -07001410 * keep the sem while scanning the cluster for mlocking pages.
1411 */
Hugh Dickinsaf8e3352009-12-14 17:58:59 -08001412 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001413 locked_vma = (vma->vm_flags & VM_LOCKED);
1414 if (!locked_vma)
1415 up_read(&vma->vm_mm->mmap_sem); /* don't need it */
1416 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001417
1418 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001419
Hugh Dickins365e9c872005-10-29 18:16:18 -07001420 /* Update high watermark before we lower rss */
1421 update_hiwater_rss(mm);
1422
Hugh Dickinsc0718802005-10-29 18:16:31 -07001423 for (; address < end; pte++, address += PAGE_SIZE) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 if (!pte_present(*pte))
1425 continue;
Linus Torvalds6aab3412005-11-28 14:34:23 -08001426 page = vm_normal_page(vma, address, *pte);
1427 BUG_ON(!page || PageAnon(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001428
Nick Pigginb291f002008-10-18 20:26:44 -07001429 if (locked_vma) {
1430 mlock_vma_page(page); /* no-op if already mlocked */
1431 if (page == check_page)
1432 ret = SWAP_MLOCK;
1433 continue; /* don't unmap */
1434 }
1435
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001436 if (ptep_clear_flush_young_notify(vma, address, pte))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437 continue;
1438
1439 /* Nuke the page table entry. */
Ben Collinseca35132005-11-29 11:45:26 -08001440 flush_cache_page(vma, address, pte_pfn(*pte));
Andrea Arcangelicddb8a52008-07-28 15:46:29 -07001441 pteval = ptep_clear_flush_notify(vma, address, pte);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001442
1443 /* If nonlinear, store the file page offset in the pte. */
1444 if (page->index != linear_page_index(vma, address))
1445 set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
1446
1447 /* Move the dirty bit to the physical page now the pte is gone. */
1448 if (pte_dirty(pteval))
1449 set_page_dirty(page);
1450
Hugh Dickinsedc315f2009-01-06 14:40:11 -08001451 page_remove_rmap(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001452 page_cache_release(page);
KAMEZAWA Hiroyukid559db02010-03-05 13:41:39 -08001453 dec_mm_counter(mm, MM_FILEPAGES);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001454 (*mapcount)--;
1455 }
Hugh Dickinsc0718802005-10-29 18:16:31 -07001456 pte_unmap_unlock(pte - 1, ptl);
Nick Pigginb291f002008-10-18 20:26:44 -07001457 if (locked_vma)
1458 up_read(&vma->vm_mm->mmap_sem);
1459 return ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460}
1461
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001462bool is_vma_temporary_stack(struct vm_area_struct *vma)
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001463{
1464 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1465
1466 if (!maybe_stack)
1467 return false;
1468
1469 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1470 VM_STACK_INCOMPLETE_SETUP)
1471 return true;
1472
1473 return false;
1474}
1475
Nick Pigginb291f002008-10-18 20:26:44 -07001476/**
1477 * try_to_unmap_anon - unmap or unlock anonymous page using the object-based
1478 * rmap method
1479 * @page: the page to unmap/unlock
Huang Shijie8051be52009-12-14 17:58:50 -08001480 * @flags: action and flags
Nick Pigginb291f002008-10-18 20:26:44 -07001481 *
1482 * Find all the mappings of a page using the mapping pointer and the vma chains
1483 * contained in the anon_vma struct it points to.
1484 *
1485 * This function is only called from try_to_unmap/try_to_munlock for
1486 * anonymous pages.
1487 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1488 * where the page was found will be held for write. So, we won't recheck
1489 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1490 * 'LOCKED.
1491 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001492static int try_to_unmap_anon(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001493{
1494 struct anon_vma *anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08001495 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001496 int ret = SWAP_AGAIN;
Nick Pigginb291f002008-10-18 20:26:44 -07001497
Linus Torvalds1da177e2005-04-16 15:20:36 -07001498 anon_vma = page_lock_anon_vma(page);
1499 if (!anon_vma)
1500 return ret;
1501
Rik van Riel5beb4932010-03-05 13:42:07 -08001502 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1503 struct vm_area_struct *vma = avc->vma;
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001504 unsigned long address;
1505
1506 /*
1507 * During exec, a temporary VMA is setup and later moved.
1508 * The VMA is moved under the anon_vma lock but not the
1509 * page tables leading to a race where migration cannot
1510 * find the migration ptes. Rather than increasing the
1511 * locking requirements of exec(), migration skips
1512 * temporary VMAs until after exec() completes.
1513 */
Konstantin Khlebnikovce1744f2012-03-21 16:33:59 -07001514 if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION) &&
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001515 is_vma_temporary_stack(vma))
1516 continue;
1517
1518 address = vma_address(page, vma);
Hugh Dickins1cb17292009-12-14 17:59:01 -08001519 if (address == -EFAULT)
1520 continue;
1521 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001522 if (ret != SWAP_AGAIN || !page_mapped(page))
1523 break;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001524 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -08001525
1526 page_unlock_anon_vma(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001527 return ret;
1528}
1529
1530/**
Nick Pigginb291f002008-10-18 20:26:44 -07001531 * try_to_unmap_file - unmap/unlock file page using the object-based rmap method
1532 * @page: the page to unmap/unlock
Andi Kleen14fa31b2009-09-16 11:50:10 +02001533 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001534 *
1535 * Find all the mappings of a page using the mapping pointer and the vma chains
1536 * contained in the address_space struct it points to.
1537 *
Nick Pigginb291f002008-10-18 20:26:44 -07001538 * This function is only called from try_to_unmap/try_to_munlock for
1539 * object-based pages.
1540 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1541 * where the page was found will be held for write. So, we won't recheck
1542 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1543 * 'LOCKED.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001544 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001545static int try_to_unmap_file(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001546{
1547 struct address_space *mapping = page->mapping;
1548 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1549 struct vm_area_struct *vma;
1550 struct prio_tree_iter iter;
1551 int ret = SWAP_AGAIN;
1552 unsigned long cursor;
1553 unsigned long max_nl_cursor = 0;
1554 unsigned long max_nl_size = 0;
1555 unsigned int mapcount;
1556
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001557 mutex_lock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001558 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickins1cb17292009-12-14 17:59:01 -08001559 unsigned long address = vma_address(page, vma);
1560 if (address == -EFAULT)
1561 continue;
1562 ret = try_to_unmap_one(page, vma, address, flags);
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001563 if (ret != SWAP_AGAIN || !page_mapped(page))
1564 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001565 }
1566
1567 if (list_empty(&mapping->i_mmap_nonlinear))
1568 goto out;
1569
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001570 /*
1571 * We don't bother to try to find the munlocked page in nonlinears.
1572 * It's costly. Instead, later, page reclaim logic may call
1573 * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily.
1574 */
1575 if (TTU_ACTION(flags) == TTU_MUNLOCK)
1576 goto out;
1577
Linus Torvalds1da177e2005-04-16 15:20:36 -07001578 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
1579 shared.vm_set.list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001580 cursor = (unsigned long) vma->vm_private_data;
1581 if (cursor > max_nl_cursor)
1582 max_nl_cursor = cursor;
1583 cursor = vma->vm_end - vma->vm_start;
1584 if (cursor > max_nl_size)
1585 max_nl_size = cursor;
1586 }
1587
Nick Pigginb291f002008-10-18 20:26:44 -07001588 if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001589 ret = SWAP_FAIL;
1590 goto out;
1591 }
1592
1593 /*
1594 * We don't try to search for this page in the nonlinear vmas,
1595 * and page_referenced wouldn't have found it anyway. Instead
1596 * just walk the nonlinear vmas trying to age and unmap some.
1597 * The mapcount of the page we came in with is irrelevant,
1598 * but even so use it as a guide to how hard we should try?
1599 */
1600 mapcount = page_mapcount(page);
1601 if (!mapcount)
1602 goto out;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001603 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001604
1605 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
1606 if (max_nl_cursor == 0)
1607 max_nl_cursor = CLUSTER_SIZE;
1608
1609 do {
1610 list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
1611 shared.vm_set.list) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612 cursor = (unsigned long) vma->vm_private_data;
Hugh Dickins839b9682005-09-03 15:54:43 -07001613 while ( cursor < max_nl_cursor &&
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614 cursor < vma->vm_end - vma->vm_start) {
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001615 if (try_to_unmap_cluster(cursor, &mapcount,
1616 vma, page) == SWAP_MLOCK)
1617 ret = SWAP_MLOCK;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001618 cursor += CLUSTER_SIZE;
1619 vma->vm_private_data = (void *) cursor;
1620 if ((int)mapcount <= 0)
1621 goto out;
1622 }
1623 vma->vm_private_data = (void *) max_nl_cursor;
1624 }
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001625 cond_resched();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001626 max_nl_cursor += CLUSTER_SIZE;
1627 } while (max_nl_cursor <= max_nl_size);
1628
1629 /*
1630 * Don't loop forever (perhaps all the remaining pages are
1631 * in locked vmas). Reset cursor on all unreserved nonlinear
1632 * vmas, now forgetting on which ones it had fallen behind.
1633 */
Hugh Dickins101d2be2005-11-21 21:32:16 -08001634 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
1635 vma->vm_private_data = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001636out:
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001637 mutex_unlock(&mapping->i_mmap_mutex);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001638 return ret;
1639}
1640
1641/**
1642 * try_to_unmap - try to remove all page table mappings to a page
1643 * @page: the page to get unmapped
Andi Kleen14fa31b2009-09-16 11:50:10 +02001644 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001645 *
1646 * Tries to remove all the page table entries which are mapping this
1647 * page, used in the pageout path. Caller must hold the page lock.
1648 * Return values are:
1649 *
1650 * SWAP_SUCCESS - we succeeded in removing all mappings
1651 * SWAP_AGAIN - we missed a mapping, try again later
1652 * SWAP_FAIL - the page is unswappable
Nick Pigginb291f002008-10-18 20:26:44 -07001653 * SWAP_MLOCK - page is mlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001654 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001655int try_to_unmap(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001656{
1657 int ret;
1658
Linus Torvalds1da177e2005-04-16 15:20:36 -07001659 BUG_ON(!PageLocked(page));
Andrea Arcangeli91600e92011-01-13 15:47:16 -08001660 VM_BUG_ON(!PageHuge(page) && PageTransHuge(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001661
Hugh Dickins5ad64682009-12-14 17:59:24 -08001662 if (unlikely(PageKsm(page)))
1663 ret = try_to_unmap_ksm(page, flags);
1664 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001665 ret = try_to_unmap_anon(page, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001666 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001667 ret = try_to_unmap_file(page, flags);
Nick Pigginb291f002008-10-18 20:26:44 -07001668 if (ret != SWAP_MLOCK && !page_mapped(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001669 ret = SWAP_SUCCESS;
1670 return ret;
1671}
Nikita Danilov81b40822005-05-01 08:58:36 -07001672
Nick Pigginb291f002008-10-18 20:26:44 -07001673/**
1674 * try_to_munlock - try to munlock a page
1675 * @page: the page to be munlocked
1676 *
1677 * Called from munlock code. Checks all of the VMAs mapping the page
1678 * to make sure nobody else has this page mlocked. The page will be
1679 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1680 *
1681 * Return values are:
1682 *
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001683 * SWAP_AGAIN - no vma is holding page mlocked, or,
Nick Pigginb291f002008-10-18 20:26:44 -07001684 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
Hugh Dickins5ad64682009-12-14 17:59:24 -08001685 * SWAP_FAIL - page cannot be located at present
Nick Pigginb291f002008-10-18 20:26:44 -07001686 * SWAP_MLOCK - page is now mlocked.
1687 */
1688int try_to_munlock(struct page *page)
1689{
1690 VM_BUG_ON(!PageLocked(page) || PageLRU(page));
1691
Hugh Dickins5ad64682009-12-14 17:59:24 -08001692 if (unlikely(PageKsm(page)))
1693 return try_to_unmap_ksm(page, TTU_MUNLOCK);
1694 else if (PageAnon(page))
Andi Kleen14fa31b2009-09-16 11:50:10 +02001695 return try_to_unmap_anon(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001696 else
Andi Kleen14fa31b2009-09-16 11:50:10 +02001697 return try_to_unmap_file(page, TTU_MUNLOCK);
Nick Pigginb291f002008-10-18 20:26:44 -07001698}
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001699
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001700void __put_anon_vma(struct anon_vma *anon_vma)
Rik van Riel76545062010-08-09 17:18:41 -07001701{
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001702 struct anon_vma *root = anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -07001703
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001704 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1705 anon_vma_free(root);
Rik van Riel76545062010-08-09 17:18:41 -07001706
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001707 anon_vma_free(anon_vma);
Rik van Riel76545062010-08-09 17:18:41 -07001708}
Rik van Riel76545062010-08-09 17:18:41 -07001709
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001710#ifdef CONFIG_MIGRATION
1711/*
1712 * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file():
1713 * Called by migrate.c to remove migration ptes, but might be used more later.
1714 */
1715static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *,
1716 struct vm_area_struct *, unsigned long, void *), void *arg)
1717{
1718 struct anon_vma *anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -08001719 struct anon_vma_chain *avc;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001720 int ret = SWAP_AGAIN;
1721
1722 /*
1723 * Note: remove_migration_ptes() cannot use page_lock_anon_vma()
1724 * because that depends on page_mapped(); but not all its usages
Mel Gorman3f6c8272010-05-24 14:32:17 -07001725 * are holding mmap_sem. Users without mmap_sem are required to
1726 * take a reference count to prevent the anon_vma disappearing
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001727 */
1728 anon_vma = page_anon_vma(page);
1729 if (!anon_vma)
1730 return ret;
Rik van Rielcba48b92010-08-09 17:18:38 -07001731 anon_vma_lock(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -08001732 list_for_each_entry(avc, &anon_vma->head, same_anon_vma) {
1733 struct vm_area_struct *vma = avc->vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001734 unsigned long address = vma_address(page, vma);
1735 if (address == -EFAULT)
1736 continue;
1737 ret = rmap_one(page, vma, address, arg);
1738 if (ret != SWAP_AGAIN)
1739 break;
1740 }
Rik van Rielcba48b92010-08-09 17:18:38 -07001741 anon_vma_unlock(anon_vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001742 return ret;
1743}
1744
1745static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *,
1746 struct vm_area_struct *, unsigned long, void *), void *arg)
1747{
1748 struct address_space *mapping = page->mapping;
1749 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1750 struct vm_area_struct *vma;
1751 struct prio_tree_iter iter;
1752 int ret = SWAP_AGAIN;
1753
1754 if (!mapping)
1755 return ret;
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001756 mutex_lock(&mapping->i_mmap_mutex);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001757 vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
1758 unsigned long address = vma_address(page, vma);
1759 if (address == -EFAULT)
1760 continue;
1761 ret = rmap_one(page, vma, address, arg);
1762 if (ret != SWAP_AGAIN)
1763 break;
1764 }
1765 /*
1766 * No nonlinear handling: being always shared, nonlinear vmas
1767 * never contain migration ptes. Decide what to do about this
1768 * limitation to linear when we need rmap_walk() on nonlinear.
1769 */
Peter Zijlstra3d48ae42011-05-24 17:12:06 -07001770 mutex_unlock(&mapping->i_mmap_mutex);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001771 return ret;
1772}
1773
1774int rmap_walk(struct page *page, int (*rmap_one)(struct page *,
1775 struct vm_area_struct *, unsigned long, void *), void *arg)
1776{
1777 VM_BUG_ON(!PageLocked(page));
1778
1779 if (unlikely(PageKsm(page)))
1780 return rmap_walk_ksm(page, rmap_one, arg);
1781 else if (PageAnon(page))
1782 return rmap_walk_anon(page, rmap_one, arg);
1783 else
1784 return rmap_walk_file(page, rmap_one, arg);
1785}
1786#endif /* CONFIG_MIGRATION */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001787
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001788#ifdef CONFIG_HUGETLB_PAGE
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001789/*
1790 * The following three functions are for anonymous (private mapped) hugepages.
1791 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1792 * and no lru code, because we handle hugepages differently from common pages.
1793 */
1794static void __hugepage_set_anon_rmap(struct page *page,
1795 struct vm_area_struct *vma, unsigned long address, int exclusive)
1796{
1797 struct anon_vma *anon_vma = vma->anon_vma;
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001798
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001799 BUG_ON(!anon_vma);
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001800
1801 if (PageAnon(page))
1802 return;
1803 if (!exclusive)
1804 anon_vma = anon_vma->root;
1805
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001806 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1807 page->mapping = (struct address_space *) anon_vma;
1808 page->index = linear_page_index(vma, address);
1809}
1810
1811void hugepage_add_anon_rmap(struct page *page,
1812 struct vm_area_struct *vma, unsigned long address)
1813{
1814 struct anon_vma *anon_vma = vma->anon_vma;
1815 int first;
Naoya Horiguchia850ea32010-09-10 13:23:06 +09001816
1817 BUG_ON(!PageLocked(page));
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001818 BUG_ON(!anon_vma);
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001819 /* address might be in next vma when migration races vma_adjust */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001820 first = atomic_inc_and_test(&page->_mapcount);
1821 if (first)
1822 __hugepage_set_anon_rmap(page, vma, address, 0);
1823}
1824
1825void hugepage_add_new_anon_rmap(struct page *page,
1826 struct vm_area_struct *vma, unsigned long address)
1827{
1828 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1829 atomic_set(&page->_mapcount, 0);
1830 __hugepage_set_anon_rmap(page, vma, address, 1);
1831}
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001832#endif /* CONFIG_HUGETLB_PAGE */