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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)
Kirill A. Shutemov88f306b2016-01-15 16:57:31 -080026 * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share)
27 * mapping->i_mmap_rwsem
28 * anon_vma->rwsem
29 * mm->page_table_lock or pte_lock
30 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
31 * swap_lock (in swap_duplicate, swap_info_get)
32 * mmlist_lock (in mmput, drain_mmlist and others)
33 * mapping->private_lock (in __set_page_dirty_buffers)
34 * mem_cgroup_{begin,end}_page_stat (memcg->move_lock)
35 * mapping->tree_lock (widely used)
36 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
37 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
38 * sb_lock (within inode_lock in fs/fs-writeback.c)
39 * mapping->tree_lock (widely used, in set_page_dirty,
40 * in arch-dependent flush_dcache_mmap_lock,
41 * within bdi.wb->list_lock in __sync_single_inode)
Andi Kleen6a460792009-09-16 11:50:15 +020042 *
Ingo Molnar5a505082012-12-02 19:56:46 +000043 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
Peter Zijlstra9b679322011-06-27 16:18:09 -070044 * ->tasklist_lock
Andi Kleen6a460792009-09-16 11:50:15 +020045 * pte map lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070046 */
47
48#include <linux/mm.h>
49#include <linux/pagemap.h>
50#include <linux/swap.h>
51#include <linux/swapops.h>
52#include <linux/slab.h>
53#include <linux/init.h>
Hugh Dickins5ad64682009-12-14 17:59:24 -080054#include <linux/ksm.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070055#include <linux/rmap.h>
56#include <linux/rcupdate.h>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040057#include <linux/export.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080058#include <linux/memcontrol.h>
Andrea Arcangelicddb8a52008-07-28 15:46:29 -070059#include <linux/mmu_notifier.h>
KOSAKI Motohiro64cdd542009-01-06 14:39:16 -080060#include <linux/migrate.h>
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +090061#include <linux/hugetlb.h>
Jan Karaef5d4372012-10-25 13:37:31 -070062#include <linux/backing-dev.h>
Vladimir Davydov33c3fc72015-09-09 15:35:45 -070063#include <linux/page_idle.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070064
65#include <asm/tlbflush.h>
66
Mel Gorman72b252a2015-09-04 15:47:32 -070067#include <trace/events/tlb.h>
68
Nick Pigginb291f002008-10-18 20:26:44 -070069#include "internal.h"
70
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070071static struct kmem_cache *anon_vma_cachep;
Rik van Riel5beb4932010-03-05 13:42:07 -080072static struct kmem_cache *anon_vma_chain_cachep;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070073
74static inline struct anon_vma *anon_vma_alloc(void)
75{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070076 struct anon_vma *anon_vma;
77
78 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
79 if (anon_vma) {
80 atomic_set(&anon_vma->refcount, 1);
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -080081 anon_vma->degree = 1; /* Reference for first vma */
82 anon_vma->parent = anon_vma;
Peter Zijlstra01d8b202011-03-22 16:32:49 -070083 /*
84 * Initialise the anon_vma root to point to itself. If called
85 * from fork, the root will be reset to the parents anon_vma.
86 */
87 anon_vma->root = anon_vma;
88 }
89
90 return anon_vma;
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070091}
92
Peter Zijlstra01d8b202011-03-22 16:32:49 -070093static inline void anon_vma_free(struct anon_vma *anon_vma)
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -070094{
Peter Zijlstra01d8b202011-03-22 16:32:49 -070095 VM_BUG_ON(atomic_read(&anon_vma->refcount));
Peter Zijlstra88c22082011-05-24 17:12:13 -070096
97 /*
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +000098 * Synchronize against page_lock_anon_vma_read() such that
Peter Zijlstra88c22082011-05-24 17:12:13 -070099 * we can safely hold the lock without the anon_vma getting
100 * freed.
101 *
102 * Relies on the full mb implied by the atomic_dec_and_test() from
103 * put_anon_vma() against the acquire barrier implied by
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000104 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
Peter Zijlstra88c22082011-05-24 17:12:13 -0700105 *
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000106 * page_lock_anon_vma_read() VS put_anon_vma()
107 * down_read_trylock() atomic_dec_and_test()
Peter Zijlstra88c22082011-05-24 17:12:13 -0700108 * LOCK MB
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000109 * atomic_read() rwsem_is_locked()
Peter Zijlstra88c22082011-05-24 17:12:13 -0700110 *
111 * LOCK should suffice since the actual taking of the lock must
112 * happen _before_ what follows.
113 */
Hugh Dickins7f39dda2014-06-04 16:05:33 -0700114 might_sleep();
Ingo Molnar5a505082012-12-02 19:56:46 +0000115 if (rwsem_is_locked(&anon_vma->root->rwsem)) {
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000116 anon_vma_lock_write(anon_vma);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -0800117 anon_vma_unlock_write(anon_vma);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700118 }
119
Adrian Bunkfdd2e5f2008-10-18 20:28:38 -0700120 kmem_cache_free(anon_vma_cachep, anon_vma);
121}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122
Linus Torvaldsdd347392011-06-17 19:05:36 -0700123static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
Rik van Riel5beb4932010-03-05 13:42:07 -0800124{
Linus Torvaldsdd347392011-06-17 19:05:36 -0700125 return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
Rik van Riel5beb4932010-03-05 13:42:07 -0800126}
127
Namhyung Kime574b5f2010-10-26 14:22:02 -0700128static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
Rik van Riel5beb4932010-03-05 13:42:07 -0800129{
130 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
131}
132
Kautuk Consul6583a842012-03-21 16:34:01 -0700133static void anon_vma_chain_link(struct vm_area_struct *vma,
134 struct anon_vma_chain *avc,
135 struct anon_vma *anon_vma)
136{
137 avc->vma = vma;
138 avc->anon_vma = anon_vma;
139 list_add(&avc->same_vma, &vma->anon_vma_chain);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700140 anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
Kautuk Consul6583a842012-03-21 16:34:01 -0700141}
142
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700143/**
144 * anon_vma_prepare - attach an anon_vma to a memory region
145 * @vma: the memory region in question
146 *
147 * This makes sure the memory mapping described by 'vma' has
148 * an 'anon_vma' attached to it, so that we can associate the
149 * anonymous pages mapped into it with that anon_vma.
150 *
151 * The common case will be that we already have one, but if
Figo.zhang23a07902010-12-27 15:14:06 +0100152 * not we either need to find an adjacent mapping that we
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700153 * can re-use the anon_vma from (very common when the only
154 * reason for splitting a vma has been mprotect()), or we
155 * allocate a new one.
156 *
157 * Anon-vma allocations are very subtle, because we may have
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000158 * optimistically looked up an anon_vma in page_lock_anon_vma_read()
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700159 * and that may actually touch the spinlock even in the newly
160 * allocated vma (it depends on RCU to make sure that the
161 * anon_vma isn't actually destroyed).
162 *
163 * As a result, we need to do proper anon_vma locking even
164 * for the new allocation. At the same time, we do not want
165 * to do any locking for the common case of already having
166 * an anon_vma.
167 *
168 * This must be called with the mmap_sem held for reading.
169 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170int anon_vma_prepare(struct vm_area_struct *vma)
171{
172 struct anon_vma *anon_vma = vma->anon_vma;
Rik van Riel5beb4932010-03-05 13:42:07 -0800173 struct anon_vma_chain *avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174
175 might_sleep();
176 if (unlikely(!anon_vma)) {
177 struct mm_struct *mm = vma->vm_mm;
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700178 struct anon_vma *allocated;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700179
Linus Torvaldsdd347392011-06-17 19:05:36 -0700180 avc = anon_vma_chain_alloc(GFP_KERNEL);
Rik van Riel5beb4932010-03-05 13:42:07 -0800181 if (!avc)
182 goto out_enomem;
183
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 anon_vma = find_mergeable_anon_vma(vma);
Linus Torvaldsd9d332e2008-10-19 10:32:20 -0700185 allocated = NULL;
186 if (!anon_vma) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 anon_vma = anon_vma_alloc();
188 if (unlikely(!anon_vma))
Rik van Riel5beb4932010-03-05 13:42:07 -0800189 goto out_enomem_free_avc;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700190 allocated = anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700191 }
192
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000193 anon_vma_lock_write(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700194 /* page_table_lock to protect against threads */
195 spin_lock(&mm->page_table_lock);
196 if (likely(!vma->anon_vma)) {
197 vma->anon_vma = anon_vma;
Kautuk Consul6583a842012-03-21 16:34:01 -0700198 anon_vma_chain_link(vma, avc, anon_vma);
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800199 /* vma reference or self-parent link for new root */
200 anon_vma->degree++;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201 allocated = NULL;
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400202 avc = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203 }
204 spin_unlock(&mm->page_table_lock);
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -0800205 anon_vma_unlock_write(anon_vma);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400206
207 if (unlikely(allocated))
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700208 put_anon_vma(allocated);
Oleg Nesterov31f2b0e2010-04-23 13:18:01 -0400209 if (unlikely(avc))
Rik van Riel5beb4932010-03-05 13:42:07 -0800210 anon_vma_chain_free(avc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211 }
212 return 0;
Rik van Riel5beb4932010-03-05 13:42:07 -0800213
214 out_enomem_free_avc:
215 anon_vma_chain_free(avc);
216 out_enomem:
217 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218}
219
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700220/*
221 * This is a useful helper function for locking the anon_vma root as
222 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
223 * have the same vma.
224 *
225 * Such anon_vma's should have the same root, so you'd expect to see
226 * just a single mutex_lock for the whole traversal.
227 */
228static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
229{
230 struct anon_vma *new_root = anon_vma->root;
231 if (new_root != root) {
232 if (WARN_ON_ONCE(root))
Ingo Molnar5a505082012-12-02 19:56:46 +0000233 up_write(&root->rwsem);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700234 root = new_root;
Ingo Molnar5a505082012-12-02 19:56:46 +0000235 down_write(&root->rwsem);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700236 }
237 return root;
238}
239
240static inline void unlock_anon_vma_root(struct anon_vma *root)
241{
242 if (root)
Ingo Molnar5a505082012-12-02 19:56:46 +0000243 up_write(&root->rwsem);
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700244}
245
Rik van Riel5beb4932010-03-05 13:42:07 -0800246/*
247 * Attach the anon_vmas from src to dst.
248 * Returns 0 on success, -ENOMEM on failure.
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800249 *
250 * If dst->anon_vma is NULL this function tries to find and reuse existing
251 * anon_vma which has no vmas and only one child anon_vma. This prevents
252 * degradation of anon_vma hierarchy to endless linear chain in case of
253 * constantly forking task. On the other hand, an anon_vma with more than one
254 * child isn't reused even if there was no alive vma, thus rmap walker has a
255 * good chance of avoiding scanning the whole hierarchy when it searches where
256 * page is mapped.
Rik van Riel5beb4932010-03-05 13:42:07 -0800257 */
258int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700259{
Rik van Riel5beb4932010-03-05 13:42:07 -0800260 struct anon_vma_chain *avc, *pavc;
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700261 struct anon_vma *root = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700262
Linus Torvalds646d87b2010-04-11 17:15:03 -0700263 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700264 struct anon_vma *anon_vma;
265
Linus Torvaldsdd347392011-06-17 19:05:36 -0700266 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
267 if (unlikely(!avc)) {
268 unlock_anon_vma_root(root);
269 root = NULL;
270 avc = anon_vma_chain_alloc(GFP_KERNEL);
271 if (!avc)
272 goto enomem_failure;
273 }
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700274 anon_vma = pavc->anon_vma;
275 root = lock_anon_vma_root(root, anon_vma);
276 anon_vma_chain_link(dst, avc, anon_vma);
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800277
278 /*
279 * Reuse existing anon_vma if its degree lower than two,
280 * that means it has no vma and only one anon_vma child.
281 *
282 * Do not chose parent anon_vma, otherwise first child
283 * will always reuse it. Root anon_vma is never reused:
284 * it has self-parent reference and at least one child.
285 */
286 if (!dst->anon_vma && anon_vma != src->anon_vma &&
287 anon_vma->degree < 2)
288 dst->anon_vma = anon_vma;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 }
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800290 if (dst->anon_vma)
291 dst->anon_vma->degree++;
Linus Torvaldsbb4aa392011-06-16 20:44:51 -0700292 unlock_anon_vma_root(root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800293 return 0;
294
295 enomem_failure:
Leon Yu3fe89b32015-03-25 15:55:11 -0700296 /*
297 * dst->anon_vma is dropped here otherwise its degree can be incorrectly
298 * decremented in unlink_anon_vmas().
299 * We can safely do this because callers of anon_vma_clone() don't care
300 * about dst->anon_vma if anon_vma_clone() failed.
301 */
302 dst->anon_vma = NULL;
Rik van Riel5beb4932010-03-05 13:42:07 -0800303 unlink_anon_vmas(dst);
304 return -ENOMEM;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700305}
306
Rik van Riel5beb4932010-03-05 13:42:07 -0800307/*
308 * Attach vma to its own anon_vma, as well as to the anon_vmas that
309 * the corresponding VMA in the parent process is attached to.
310 * Returns 0 on success, non-zero on failure.
311 */
312int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700313{
Rik van Riel5beb4932010-03-05 13:42:07 -0800314 struct anon_vma_chain *avc;
315 struct anon_vma *anon_vma;
Daniel Forrestc4ea95d2014-12-02 15:59:42 -0800316 int error;
Rik van Riel5beb4932010-03-05 13:42:07 -0800317
318 /* Don't bother if the parent process has no anon_vma here. */
319 if (!pvma->anon_vma)
320 return 0;
321
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800322 /* Drop inherited anon_vma, we'll reuse existing or allocate new. */
323 vma->anon_vma = NULL;
324
Rik van Riel5beb4932010-03-05 13:42:07 -0800325 /*
326 * First, attach the new VMA to the parent VMA's anon_vmas,
327 * so rmap can find non-COWed pages in child processes.
328 */
Daniel Forrestc4ea95d2014-12-02 15:59:42 -0800329 error = anon_vma_clone(vma, pvma);
330 if (error)
331 return error;
Rik van Riel5beb4932010-03-05 13:42:07 -0800332
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800333 /* An existing anon_vma has been reused, all done then. */
334 if (vma->anon_vma)
335 return 0;
336
Rik van Riel5beb4932010-03-05 13:42:07 -0800337 /* 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 Riel5c341ee12010-08-09 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;
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800350 anon_vma->parent = pvma->anon_vma;
Rik van Riel76545062010-08-09 17:18:41 -0700351 /*
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700352 * With refcounts, an anon_vma can stay around longer than the
353 * process it belongs to. The root anon_vma needs to be pinned until
354 * this anon_vma is freed, because the lock lives in the root.
Rik van Riel76545062010-08-09 17:18:41 -0700355 */
356 get_anon_vma(anon_vma->root);
Rik van Riel5beb4932010-03-05 13:42:07 -0800357 /* Mark this anon_vma as the one where our new (COWed) pages go. */
358 vma->anon_vma = anon_vma;
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000359 anon_vma_lock_write(anon_vma);
Rik van Riel5c341ee12010-08-09 17:18:39 -0700360 anon_vma_chain_link(vma, avc, anon_vma);
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800361 anon_vma->parent->degree++;
Konstantin Khlebnikov08b52702013-02-22 16:34:40 -0800362 anon_vma_unlock_write(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800363
364 return 0;
365
366 out_error_free_anon_vma:
Peter Zijlstra01d8b202011-03-22 16:32:49 -0700367 put_anon_vma(anon_vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800368 out_error:
Rik van Riel4946d542010-04-05 12:13:33 -0400369 unlink_anon_vmas(vma);
Rik van Riel5beb4932010-03-05 13:42:07 -0800370 return -ENOMEM;
371}
372
Rik van Riel5beb4932010-03-05 13:42:07 -0800373void unlink_anon_vmas(struct vm_area_struct *vma)
374{
375 struct anon_vma_chain *avc, *next;
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200376 struct anon_vma *root = NULL;
Rik van Riel5beb4932010-03-05 13:42:07 -0800377
Rik van Riel5c341ee12010-08-09 17:18:39 -0700378 /*
379 * Unlink each anon_vma chained to the VMA. This list is ordered
380 * from newest to oldest, ensuring the root anon_vma gets freed last.
381 */
Rik van Riel5beb4932010-03-05 13:42:07 -0800382 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200383 struct anon_vma *anon_vma = avc->anon_vma;
384
385 root = lock_anon_vma_root(root, anon_vma);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700386 anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200387
388 /*
389 * Leave empty anon_vmas on the list - we'll need
390 * to free them outside the lock.
391 */
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800392 if (RB_EMPTY_ROOT(&anon_vma->rb_root)) {
393 anon_vma->parent->degree--;
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200394 continue;
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800395 }
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200396
397 list_del(&avc->same_vma);
398 anon_vma_chain_free(avc);
399 }
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800400 if (vma->anon_vma)
401 vma->anon_vma->degree--;
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200402 unlock_anon_vma_root(root);
403
404 /*
405 * Iterate the list once more, it now only contains empty and unlinked
406 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
Ingo Molnar5a505082012-12-02 19:56:46 +0000407 * needing to write-acquire the anon_vma->root->rwsem.
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200408 */
409 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
410 struct anon_vma *anon_vma = avc->anon_vma;
411
Konstantin Khlebnikov7a3ef202015-01-08 14:32:15 -0800412 BUG_ON(anon_vma->degree);
Peter Zijlstraeee2acb2011-06-17 13:54:23 +0200413 put_anon_vma(anon_vma);
414
Rik van Riel5beb4932010-03-05 13:42:07 -0800415 list_del(&avc->same_vma);
416 anon_vma_chain_free(avc);
417 }
418}
419
Alexey Dobriyan51cc5062008-07-25 19:45:34 -0700420static void anon_vma_ctor(void *data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421{
Christoph Lametera35afb82007-05-16 22:10:57 -0700422 struct anon_vma *anon_vma = data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700423
Ingo Molnar5a505082012-12-02 19:56:46 +0000424 init_rwsem(&anon_vma->rwsem);
Peter Zijlstra83813262011-03-22 16:32:48 -0700425 atomic_set(&anon_vma->refcount, 0);
Michel Lespinassebf181b92012-10-08 16:31:39 -0700426 anon_vma->rb_root = RB_ROOT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427}
428
429void __init anon_vma_init(void)
430{
431 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
Vladimir Davydov5d097052016-01-14 15:18:21 -0800432 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC|SLAB_ACCOUNT,
433 anon_vma_ctor);
434 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain,
435 SLAB_PANIC|SLAB_ACCOUNT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700436}
437
438/*
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700439 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
440 *
441 * Since there is no serialization what so ever against page_remove_rmap()
442 * the best this function can do is return a locked anon_vma that might
443 * have been relevant to this page.
444 *
445 * The page might have been remapped to a different anon_vma or the anon_vma
446 * returned may already be freed (and even reused).
447 *
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200448 * In case it was remapped to a different anon_vma, the new anon_vma will be a
449 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
450 * ensure that any anon_vma obtained from the page will still be valid for as
451 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
452 *
Peter Zijlstra6111e4c2011-05-24 17:12:08 -0700453 * All users of this function must be very careful when walking the anon_vma
454 * chain and verify that the page in question is indeed mapped in it
455 * [ something equivalent to page_mapped_in_vma() ].
456 *
457 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
458 * that the anon_vma pointer from page->mapping is valid if there is a
459 * mapcount, we can dereference the anon_vma after observing those.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700460 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700461struct anon_vma *page_get_anon_vma(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700462{
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700463 struct anon_vma *anon_vma = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700464 unsigned long anon_mapping;
465
466 rcu_read_lock();
Jason Low4db0c3c2015-04-15 16:14:08 -0700467 anon_mapping = (unsigned long)READ_ONCE(page->mapping);
Hugh Dickins3ca7b3c2009-12-14 17:58:57 -0800468 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469 goto out;
470 if (!page_mapped(page))
471 goto out;
472
473 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700474 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
475 anon_vma = NULL;
476 goto out;
477 }
Hugh Dickinsf18194272010-08-25 23:12:54 -0700478
479 /*
480 * If this page is still mapped, then its anon_vma cannot have been
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700481 * freed. But if it has been unmapped, we have no security against the
482 * anon_vma structure being freed and reused (for another anon_vma:
483 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
484 * above cannot corrupt).
Hugh Dickinsf18194272010-08-25 23:12:54 -0700485 */
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700486 if (!page_mapped(page)) {
Hugh Dickins7f39dda2014-06-04 16:05:33 -0700487 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700488 put_anon_vma(anon_vma);
Hugh Dickins7f39dda2014-06-04 16:05:33 -0700489 return NULL;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700490 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700491out:
492 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700493
494 return anon_vma;
495}
496
Peter Zijlstra88c22082011-05-24 17:12:13 -0700497/*
498 * Similar to page_get_anon_vma() except it locks the anon_vma.
499 *
500 * Its a little more complex as it tries to keep the fast path to a single
501 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
502 * reference like with page_get_anon_vma() and then block on the mutex.
503 */
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000504struct anon_vma *page_lock_anon_vma_read(struct page *page)
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700505{
Peter Zijlstra88c22082011-05-24 17:12:13 -0700506 struct anon_vma *anon_vma = NULL;
Hugh Dickinseee0f252011-05-28 13:20:21 -0700507 struct anon_vma *root_anon_vma;
Peter Zijlstra88c22082011-05-24 17:12:13 -0700508 unsigned long anon_mapping;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700509
Peter Zijlstra88c22082011-05-24 17:12:13 -0700510 rcu_read_lock();
Jason Low4db0c3c2015-04-15 16:14:08 -0700511 anon_mapping = (unsigned long)READ_ONCE(page->mapping);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700512 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
513 goto out;
514 if (!page_mapped(page))
515 goto out;
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700516
Peter Zijlstra88c22082011-05-24 17:12:13 -0700517 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
Jason Low4db0c3c2015-04-15 16:14:08 -0700518 root_anon_vma = READ_ONCE(anon_vma->root);
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000519 if (down_read_trylock(&root_anon_vma->rwsem)) {
Peter Zijlstra88c22082011-05-24 17:12:13 -0700520 /*
Hugh Dickinseee0f252011-05-28 13:20:21 -0700521 * If the page is still mapped, then this anon_vma is still
522 * its anon_vma, and holding the mutex ensures that it will
Peter Zijlstrabc658c92011-05-29 10:33:44 +0200523 * not go away, see anon_vma_free().
Peter Zijlstra88c22082011-05-24 17:12:13 -0700524 */
Hugh Dickinseee0f252011-05-28 13:20:21 -0700525 if (!page_mapped(page)) {
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000526 up_read(&root_anon_vma->rwsem);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700527 anon_vma = NULL;
528 }
529 goto out;
530 }
531
532 /* trylock failed, we got to sleep */
533 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
534 anon_vma = NULL;
535 goto out;
536 }
537
538 if (!page_mapped(page)) {
Hugh Dickins7f39dda2014-06-04 16:05:33 -0700539 rcu_read_unlock();
Peter Zijlstra88c22082011-05-24 17:12:13 -0700540 put_anon_vma(anon_vma);
Hugh Dickins7f39dda2014-06-04 16:05:33 -0700541 return NULL;
Peter Zijlstra88c22082011-05-24 17:12:13 -0700542 }
543
544 /* we pinned the anon_vma, its safe to sleep */
545 rcu_read_unlock();
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000546 anon_vma_lock_read(anon_vma);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700547
548 if (atomic_dec_and_test(&anon_vma->refcount)) {
549 /*
550 * Oops, we held the last refcount, release the lock
551 * and bail -- can't simply use put_anon_vma() because
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000552 * we'll deadlock on the anon_vma_lock_write() recursion.
Peter Zijlstra88c22082011-05-24 17:12:13 -0700553 */
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000554 anon_vma_unlock_read(anon_vma);
Peter Zijlstra88c22082011-05-24 17:12:13 -0700555 __put_anon_vma(anon_vma);
556 anon_vma = NULL;
557 }
558
559 return anon_vma;
560
561out:
562 rcu_read_unlock();
Peter Zijlstra746b18d2011-05-24 17:12:10 -0700563 return anon_vma;
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800564}
565
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000566void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800567{
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +0000568 anon_vma_unlock_read(anon_vma);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700569}
570
Mel Gorman72b252a2015-09-04 15:47:32 -0700571#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
572static void percpu_flush_tlb_batch_pages(void *data)
573{
574 /*
575 * All TLB entries are flushed on the assumption that it is
576 * cheaper to flush all TLBs and let them be refilled than
577 * flushing individual PFNs. Note that we do not track mm's
578 * to flush as that might simply be multiple full TLB flushes
579 * for no gain.
580 */
581 count_vm_tlb_event(NR_TLB_REMOTE_FLUSH_RECEIVED);
582 flush_tlb_local();
583}
584
585/*
586 * Flush TLB entries for recently unmapped pages from remote CPUs. It is
587 * important if a PTE was dirty when it was unmapped that it's flushed
588 * before any IO is initiated on the page to prevent lost writes. Similarly,
589 * it must be flushed before freeing to prevent data leakage.
590 */
591void try_to_unmap_flush(void)
592{
593 struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
594 int cpu;
595
596 if (!tlb_ubc->flush_required)
597 return;
598
599 cpu = get_cpu();
600
601 trace_tlb_flush(TLB_REMOTE_SHOOTDOWN, -1UL);
602
603 if (cpumask_test_cpu(cpu, &tlb_ubc->cpumask))
604 percpu_flush_tlb_batch_pages(&tlb_ubc->cpumask);
605
606 if (cpumask_any_but(&tlb_ubc->cpumask, cpu) < nr_cpu_ids) {
607 smp_call_function_many(&tlb_ubc->cpumask,
608 percpu_flush_tlb_batch_pages, (void *)tlb_ubc, true);
609 }
610 cpumask_clear(&tlb_ubc->cpumask);
611 tlb_ubc->flush_required = false;
Mel Gormand950c942015-09-04 15:47:35 -0700612 tlb_ubc->writable = false;
Mel Gorman72b252a2015-09-04 15:47:32 -0700613 put_cpu();
614}
615
Mel Gormand950c942015-09-04 15:47:35 -0700616/* Flush iff there are potentially writable TLB entries that can race with IO */
617void try_to_unmap_flush_dirty(void)
618{
619 struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
620
621 if (tlb_ubc->writable)
622 try_to_unmap_flush();
623}
624
Mel Gorman72b252a2015-09-04 15:47:32 -0700625static void set_tlb_ubc_flush_pending(struct mm_struct *mm,
Mel Gormand950c942015-09-04 15:47:35 -0700626 struct page *page, bool writable)
Mel Gorman72b252a2015-09-04 15:47:32 -0700627{
628 struct tlbflush_unmap_batch *tlb_ubc = &current->tlb_ubc;
629
630 cpumask_or(&tlb_ubc->cpumask, &tlb_ubc->cpumask, mm_cpumask(mm));
631 tlb_ubc->flush_required = true;
Mel Gormand950c942015-09-04 15:47:35 -0700632
633 /*
634 * If the PTE was dirty then it's best to assume it's writable. The
635 * caller must use try_to_unmap_flush_dirty() or try_to_unmap_flush()
636 * before the page is queued for IO.
637 */
638 if (writable)
639 tlb_ubc->writable = true;
Mel Gorman72b252a2015-09-04 15:47:32 -0700640}
641
642/*
643 * Returns true if the TLB flush should be deferred to the end of a batch of
644 * unmap operations to reduce IPIs.
645 */
646static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
647{
648 bool should_defer = false;
649
650 if (!(flags & TTU_BATCH_FLUSH))
651 return false;
652
653 /* If remote CPUs need to be flushed then defer batch the flush */
654 if (cpumask_any_but(mm_cpumask(mm), get_cpu()) < nr_cpu_ids)
655 should_defer = true;
656 put_cpu();
657
658 return should_defer;
659}
660#else
661static void set_tlb_ubc_flush_pending(struct mm_struct *mm,
Mel Gormand950c942015-09-04 15:47:35 -0700662 struct page *page, bool writable)
Mel Gorman72b252a2015-09-04 15:47:32 -0700663{
664}
665
666static bool should_defer_flush(struct mm_struct *mm, enum ttu_flags flags)
667{
668 return false;
669}
670#endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
671
Linus Torvalds1da177e2005-04-16 15:20:36 -0700672/*
Huang Shijiebf89c8c2009-10-01 15:44:04 -0700673 * At what user virtual address is page expected in vma?
Naoya Horiguchiab941e02010-05-11 14:06:55 -0700674 * Caller should check the page is actually part of the vma.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 */
676unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
677{
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700678 unsigned long address;
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700679 if (PageAnon(page)) {
Hugh Dickins4829b902010-10-02 17:46:06 -0700680 struct anon_vma *page__anon_vma = page_anon_vma(page);
681 /*
682 * Note: swapoff's unuse_vma() is more efficient with this
683 * check, and needs it to match anon_vma when KSM is active.
684 */
685 if (!vma->anon_vma || !page__anon_vma ||
686 vma->anon_vma->root != page__anon_vma->root)
Andrea Arcangeli21d0d442010-08-09 17:19:10 -0700687 return -EFAULT;
Kirill A. Shutemov27ba0642015-02-10 14:09:59 -0800688 } else if (page->mapping) {
689 if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700690 return -EFAULT;
691 } else
692 return -EFAULT;
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700693 address = __vma_address(page, vma);
694 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
695 return -EFAULT;
696 return address;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700697}
698
Bob Liu62190492012-12-11 16:00:37 -0800699pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
700{
701 pgd_t *pgd;
702 pud_t *pud;
703 pmd_t *pmd = NULL;
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -0700704 pmd_t pmde;
Bob Liu62190492012-12-11 16:00:37 -0800705
706 pgd = pgd_offset(mm, address);
707 if (!pgd_present(*pgd))
708 goto out;
709
710 pud = pud_offset(pgd, address);
711 if (!pud_present(*pud))
712 goto out;
713
714 pmd = pmd_offset(pud, address);
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -0700715 /*
Aneesh Kumar K.V8809aa22015-06-24 16:57:44 -0700716 * Some THP functions use the sequence pmdp_huge_clear_flush(), set_pmd_at()
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -0700717 * without holding anon_vma lock for write. So when looking for a
718 * genuine pmde (in which to find pte), test present and !THP together.
719 */
Christian Borntraegere37c6982014-12-07 21:41:33 +0100720 pmde = *pmd;
721 barrier();
Hugh Dickinsf72e7dc2014-06-23 13:22:05 -0700722 if (!pmd_present(pmde) || pmd_trans_huge(pmde))
Bob Liu62190492012-12-11 16:00:37 -0800723 pmd = NULL;
724out:
725 return pmd;
726}
727
Linus Torvalds1da177e2005-04-16 15:20:36 -0700728/*
Nikita Danilov81b40822005-05-01 08:58:36 -0700729 * Check that @page is mapped at @address into @mm.
730 *
Nick Piggin479db0b2008-08-20 14:09:18 -0700731 * If @sync is false, page_check_address may perform a racy check to avoid
732 * the page table lock when the pte is not present (helpful when reclaiming
733 * highly shared pages).
734 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700735 * On success returns with pte mapped and locked.
Nikita Danilov81b40822005-05-01 08:58:36 -0700736 */
Namhyung Kime9a81a82010-10-26 14:22:01 -0700737pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
Nick Piggin479db0b2008-08-20 14:09:18 -0700738 unsigned long address, spinlock_t **ptlp, int sync)
Nikita Danilov81b40822005-05-01 08:58:36 -0700739{
Nikita Danilov81b40822005-05-01 08:58:36 -0700740 pmd_t *pmd;
741 pte_t *pte;
Hugh Dickinsc0718802005-10-29 18:16:31 -0700742 spinlock_t *ptl;
Nikita Danilov81b40822005-05-01 08:58:36 -0700743
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900744 if (unlikely(PageHuge(page))) {
Jianguo Wu98398c32013-12-18 17:08:59 -0800745 /* when pud is not present, pte will be NULL */
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900746 pte = huge_pte_offset(mm, address);
Jianguo Wu98398c32013-12-18 17:08:59 -0800747 if (!pte)
748 return NULL;
749
Kirill A. Shutemovcb900f42013-11-14 14:31:02 -0800750 ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900751 goto check;
752 }
753
Bob Liu62190492012-12-11 16:00:37 -0800754 pmd = mm_find_pmd(mm, address);
755 if (!pmd)
Hugh Dickinsc0718802005-10-29 18:16:31 -0700756 return NULL;
757
Hugh Dickinsc0718802005-10-29 18:16:31 -0700758 pte = pte_offset_map(pmd, address);
759 /* Make a quick check before getting the lock */
Nick Piggin479db0b2008-08-20 14:09:18 -0700760 if (!sync && !pte_present(*pte)) {
Hugh Dickinsc0718802005-10-29 18:16:31 -0700761 pte_unmap(pte);
762 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700763 }
Hugh Dickinsc0718802005-10-29 18:16:31 -0700764
Hugh Dickins4c21e2f2005-10-29 18:16:40 -0700765 ptl = pte_lockptr(mm, pmd);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +0900766check:
Hugh Dickinsc0718802005-10-29 18:16:31 -0700767 spin_lock(ptl);
768 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
769 *ptlp = ptl;
770 return pte;
771 }
772 pte_unmap_unlock(pte, ptl);
773 return NULL;
Nikita Danilov81b40822005-05-01 08:58:36 -0700774}
775
Nick Pigginb291f002008-10-18 20:26:44 -0700776/**
777 * page_mapped_in_vma - check whether a page is really mapped in a VMA
778 * @page: the page to test
779 * @vma: the VMA to test
780 *
781 * Returns 1 if the page is mapped into the page tables of the VMA, 0
782 * if the page is not mapped into the page tables of this VMA. Only
783 * valid for normal file or anonymous VMAs.
784 */
Andi Kleen6a460792009-09-16 11:50:15 +0200785int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
Nick Pigginb291f002008-10-18 20:26:44 -0700786{
787 unsigned long address;
788 pte_t *pte;
789 spinlock_t *ptl;
790
Michel Lespinasse86c2ad12012-10-08 16:31:42 -0700791 address = __vma_address(page, vma);
792 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
Nick Pigginb291f002008-10-18 20:26:44 -0700793 return 0;
794 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
795 if (!pte) /* the page is not in this mm */
796 return 0;
797 pte_unmap_unlock(pte, ptl);
798
799 return 1;
800}
801
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800802#ifdef CONFIG_TRANSPARENT_HUGEPAGE
803/*
804 * Check that @page is mapped at @address into @mm. In contrast to
805 * page_check_address(), this function can handle transparent huge pages.
806 *
807 * On success returns true with pte mapped and locked. For PMD-mapped
808 * transparent huge pages *@ptep is set to NULL.
809 */
810bool page_check_address_transhuge(struct page *page, struct mm_struct *mm,
811 unsigned long address, pmd_t **pmdp,
812 pte_t **ptep, spinlock_t **ptlp)
813{
814 pgd_t *pgd;
815 pud_t *pud;
816 pmd_t *pmd;
817 pte_t *pte;
818 spinlock_t *ptl;
819
820 if (unlikely(PageHuge(page))) {
821 /* when pud is not present, pte will be NULL */
822 pte = huge_pte_offset(mm, address);
823 if (!pte)
824 return false;
825
826 ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
827 pmd = NULL;
828 goto check_pte;
829 }
830
831 pgd = pgd_offset(mm, address);
832 if (!pgd_present(*pgd))
833 return false;
834 pud = pud_offset(pgd, address);
835 if (!pud_present(*pud))
836 return false;
837 pmd = pmd_offset(pud, address);
838
839 if (pmd_trans_huge(*pmd)) {
840 ptl = pmd_lock(mm, pmd);
841 if (!pmd_present(*pmd))
842 goto unlock_pmd;
843 if (unlikely(!pmd_trans_huge(*pmd))) {
844 spin_unlock(ptl);
845 goto map_pte;
846 }
847
848 if (pmd_page(*pmd) != page)
849 goto unlock_pmd;
850
851 pte = NULL;
852 goto found;
853unlock_pmd:
854 spin_unlock(ptl);
855 return false;
856 } else {
857 pmd_t pmde = *pmd;
858
859 barrier();
860 if (!pmd_present(pmde) || pmd_trans_huge(pmde))
861 return false;
862 }
863map_pte:
864 pte = pte_offset_map(pmd, address);
865 if (!pte_present(*pte)) {
866 pte_unmap(pte);
867 return false;
868 }
869
870 ptl = pte_lockptr(mm, pmd);
871check_pte:
872 spin_lock(ptl);
873
874 if (!pte_present(*pte)) {
875 pte_unmap_unlock(pte, ptl);
876 return false;
877 }
878
879 /* THP can be referenced by any subpage */
880 if (pte_pfn(*pte) - page_to_pfn(page) >= hpage_nr_pages(page)) {
881 pte_unmap_unlock(pte, ptl);
882 return false;
883 }
884found:
885 *ptep = pte;
886 *pmdp = pmd;
887 *ptlp = ptl;
888 return true;
889}
890#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
891
Joonsoo Kim9f326242014-01-21 15:49:53 -0800892struct page_referenced_arg {
893 int mapcount;
894 int referenced;
895 unsigned long vm_flags;
896 struct mem_cgroup *memcg;
897};
Nikita Danilov81b40822005-05-01 08:58:36 -0700898/*
Joonsoo Kim9f326242014-01-21 15:49:53 -0800899 * arg: page_referenced_arg will be passed
Linus Torvalds1da177e2005-04-16 15:20:36 -0700900 */
Kirill A. Shutemovac769502014-06-04 16:08:17 -0700901static int page_referenced_one(struct page *page, struct vm_area_struct *vma,
Joonsoo Kim9f326242014-01-21 15:49:53 -0800902 unsigned long address, void *arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700903{
904 struct mm_struct *mm = vma->vm_mm;
Joonsoo Kim9f326242014-01-21 15:49:53 -0800905 struct page_referenced_arg *pra = arg;
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800906 pmd_t *pmd;
907 pte_t *pte;
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800908 spinlock_t *ptl;
909 int referenced = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800911 if (!page_check_address_transhuge(page, mm, address, &pmd, &pte, &ptl))
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800912 return SWAP_AGAIN;
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800913
914 if (vma->vm_flags & VM_LOCKED) {
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800915 if (pte)
916 pte_unmap(pte);
917 spin_unlock(ptl);
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800918 pra->vm_flags |= VM_LOCKED;
919 return SWAP_FAIL; /* To break the loop */
920 }
921
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800922 if (pte) {
923 if (ptep_clear_flush_young_notify(vma, address, pte)) {
924 /*
925 * Don't treat a reference through a sequentially read
926 * mapping as such. If the page has been used in
927 * another mapping, we will catch it; if this other
928 * mapping is already gone, the unmap path will have
929 * set PG_referenced or activated the page.
930 */
931 if (likely(!(vma->vm_flags & VM_SEQ_READ)))
932 referenced++;
933 }
934 pte_unmap(pte);
935 } else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
936 if (pmdp_clear_flush_young_notify(vma, address, pmd))
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800937 referenced++;
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800938 } else {
939 /* unexpected pmd-mapped page? */
940 WARN_ON_ONCE(1);
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800941 }
Vladimir Davydov8749cfe2016-01-15 16:54:45 -0800942 spin_unlock(ptl);
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800943
Vladimir Davydov33c3fc72015-09-09 15:35:45 -0700944 if (referenced)
945 clear_page_idle(page);
946 if (test_and_clear_page_young(page))
947 referenced++;
948
Joonsoo Kim9f326242014-01-21 15:49:53 -0800949 if (referenced) {
950 pra->referenced++;
951 pra->vm_flags |= vma->vm_flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700952 }
Oleg Nesterov34bbd702007-02-28 20:13:49 -0800953
Joonsoo Kim9f326242014-01-21 15:49:53 -0800954 pra->mapcount--;
955 if (!pra->mapcount)
956 return SWAP_SUCCESS; /* To break the loop */
957
958 return SWAP_AGAIN;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700959}
960
Joonsoo Kim9f326242014-01-21 15:49:53 -0800961static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700962{
Joonsoo Kim9f326242014-01-21 15:49:53 -0800963 struct page_referenced_arg *pra = arg;
964 struct mem_cgroup *memcg = pra->memcg;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700965
Joonsoo Kim9f326242014-01-21 15:49:53 -0800966 if (!mm_match_cgroup(vma->vm_mm, memcg))
967 return true;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700968
Joonsoo Kim9f326242014-01-21 15:49:53 -0800969 return false;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700970}
971
972/**
973 * page_referenced - test if the page was referenced
974 * @page: the page to test
975 * @is_locked: caller holds lock on the page
Johannes Weiner72835c82012-01-12 17:18:32 -0800976 * @memcg: target memory cgroup
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700977 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
Linus Torvalds1da177e2005-04-16 15:20:36 -0700978 *
979 * Quick test_and_clear_referenced for all mappings to a page,
980 * returns the number of ptes which referenced the page.
981 */
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700982int page_referenced(struct page *page,
983 int is_locked,
Johannes Weiner72835c82012-01-12 17:18:32 -0800984 struct mem_cgroup *memcg,
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700985 unsigned long *vm_flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700986{
Joonsoo Kim9f326242014-01-21 15:49:53 -0800987 int ret;
Hugh Dickins5ad64682009-12-14 17:59:24 -0800988 int we_locked = 0;
Joonsoo Kim9f326242014-01-21 15:49:53 -0800989 struct page_referenced_arg pra = {
Kirill A. Shutemovb20ce5e2016-01-15 16:54:37 -0800990 .mapcount = total_mapcount(page),
Joonsoo Kim9f326242014-01-21 15:49:53 -0800991 .memcg = memcg,
992 };
993 struct rmap_walk_control rwc = {
994 .rmap_one = page_referenced_one,
995 .arg = (void *)&pra,
996 .anon_lock = page_lock_anon_vma_read,
997 };
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998
Wu Fengguang6fe6b7e2009-06-16 15:33:05 -0700999 *vm_flags = 0;
Joonsoo Kim9f326242014-01-21 15:49:53 -08001000 if (!page_mapped(page))
1001 return 0;
1002
1003 if (!page_rmapping(page))
1004 return 0;
1005
1006 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
1007 we_locked = trylock_page(page);
1008 if (!we_locked)
1009 return 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001010 }
Joonsoo Kim9f326242014-01-21 15:49:53 -08001011
1012 /*
1013 * If we are reclaiming on behalf of a cgroup, skip
1014 * counting on behalf of references from different
1015 * cgroups
1016 */
1017 if (memcg) {
1018 rwc.invalid_vma = invalid_page_referenced_vma;
1019 }
1020
1021 ret = rmap_walk(page, &rwc);
1022 *vm_flags = pra.vm_flags;
1023
1024 if (we_locked)
1025 unlock_page(page);
1026
1027 return pra.referenced;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028}
1029
Hugh Dickins1cb17292009-12-14 17:59:01 -08001030static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
Joonsoo Kim9853a402014-01-21 15:49:55 -08001031 unsigned long address, void *arg)
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001032{
1033 struct mm_struct *mm = vma->vm_mm;
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +01001034 pte_t *pte;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001035 spinlock_t *ptl;
1036 int ret = 0;
Joonsoo Kim9853a402014-01-21 15:49:55 -08001037 int *cleaned = arg;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001038
Nick Piggin479db0b2008-08-20 14:09:18 -07001039 pte = page_check_address(page, mm, address, &ptl, 1);
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001040 if (!pte)
1041 goto out;
1042
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +01001043 if (pte_dirty(*pte) || pte_write(*pte)) {
1044 pte_t entry;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001045
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +01001046 flush_cache_page(vma, address, pte_pfn(*pte));
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001047 entry = ptep_clear_flush(vma, address, pte);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +01001048 entry = pte_wrprotect(entry);
1049 entry = pte_mkclean(entry);
Al Virod6e88e62006-12-29 16:48:35 -08001050 set_pte_at(mm, address, pte, entry);
Peter Zijlstrac2fda5f2006-12-22 14:25:52 +01001051 ret = 1;
1052 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001053
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001054 pte_unmap_unlock(pte, ptl);
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001055
Joonsoo Kim9853a402014-01-21 15:49:55 -08001056 if (ret) {
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001057 mmu_notifier_invalidate_page(mm, address);
Joonsoo Kim9853a402014-01-21 15:49:55 -08001058 (*cleaned)++;
1059 }
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001060out:
Joonsoo Kim9853a402014-01-21 15:49:55 -08001061 return SWAP_AGAIN;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001062}
1063
Joonsoo Kim9853a402014-01-21 15:49:55 -08001064static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001065{
Joonsoo Kim9853a402014-01-21 15:49:55 -08001066 if (vma->vm_flags & VM_SHARED)
Fengguang Wu871beb82014-01-23 15:53:41 -08001067 return false;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001068
Fengguang Wu871beb82014-01-23 15:53:41 -08001069 return true;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001070}
1071
1072int page_mkclean(struct page *page)
1073{
Joonsoo Kim9853a402014-01-21 15:49:55 -08001074 int cleaned = 0;
1075 struct address_space *mapping;
1076 struct rmap_walk_control rwc = {
1077 .arg = (void *)&cleaned,
1078 .rmap_one = page_mkclean_one,
1079 .invalid_vma = invalid_mkclean_vma,
1080 };
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001081
1082 BUG_ON(!PageLocked(page));
1083
Joonsoo Kim9853a402014-01-21 15:49:55 -08001084 if (!page_mapped(page))
1085 return 0;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001086
Joonsoo Kim9853a402014-01-21 15:49:55 -08001087 mapping = page_mapping(page);
1088 if (!mapping)
1089 return 0;
1090
1091 rmap_walk(page, &rwc);
1092
1093 return cleaned;
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001094}
Jaya Kumar60b59be2007-05-08 00:37:37 -07001095EXPORT_SYMBOL_GPL(page_mkclean);
Peter Zijlstrad08b3852006-09-25 23:30:57 -07001096
Linus Torvalds1da177e2005-04-16 15:20:36 -07001097/**
Rik van Rielc44b6742010-03-05 13:42:09 -08001098 * page_move_anon_rmap - move a page to our anon_vma
1099 * @page: the page to move to our anon_vma
1100 * @vma: the vma the page belongs to
1101 * @address: the user virtual address mapped
1102 *
1103 * When a page belongs exclusively to one process after a COW event,
1104 * that page can be moved into the anon_vma that belongs to just that
1105 * process, so the rmap code will not search the parent or sibling
1106 * processes.
1107 */
1108void page_move_anon_rmap(struct page *page,
1109 struct vm_area_struct *vma, unsigned long address)
1110{
1111 struct anon_vma *anon_vma = vma->anon_vma;
1112
Sasha Levin309381fea2014-01-23 15:52:54 -08001113 VM_BUG_ON_PAGE(!PageLocked(page), page);
Sasha Levin81d1b092014-10-09 15:28:10 -07001114 VM_BUG_ON_VMA(!anon_vma, vma);
Sasha Levin309381fea2014-01-23 15:52:54 -08001115 VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
Rik van Rielc44b6742010-03-05 13:42:09 -08001116
1117 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
Vladimir Davydov414e2fb2015-06-24 16:56:56 -07001118 /*
1119 * Ensure that anon_vma and the PAGE_MAPPING_ANON bit are written
1120 * simultaneously, so a concurrent reader (eg page_referenced()'s
1121 * PageAnon()) will not see one without the other.
1122 */
1123 WRITE_ONCE(page->mapping, (struct address_space *) anon_vma);
Rik van Rielc44b6742010-03-05 13:42:09 -08001124}
1125
1126/**
Andi Kleen4e1c1972010-09-22 12:43:56 +02001127 * __page_set_anon_rmap - set up new anonymous rmap
1128 * @page: Page to add to rmap
1129 * @vma: VM area to add page to.
1130 * @address: User virtual address of the mapping
Rik van Riele8a03fe2010-04-14 17:59:28 -04001131 * @exclusive: the page is exclusively owned by the current process
Nick Piggin9617d952006-01-06 00:11:12 -08001132 */
1133static void __page_set_anon_rmap(struct page *page,
Rik van Riele8a03fe2010-04-14 17:59:28 -04001134 struct vm_area_struct *vma, unsigned long address, int exclusive)
Nick Piggin9617d952006-01-06 00:11:12 -08001135{
Rik van Riele8a03fe2010-04-14 17:59:28 -04001136 struct anon_vma *anon_vma = vma->anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -08001137
Rik van Riele8a03fe2010-04-14 17:59:28 -04001138 BUG_ON(!anon_vma);
Linus Torvaldsea900022010-04-12 12:44:29 -07001139
Andi Kleen4e1c1972010-09-22 12:43:56 +02001140 if (PageAnon(page))
1141 return;
1142
Linus Torvaldsea900022010-04-12 12:44:29 -07001143 /*
Rik van Riele8a03fe2010-04-14 17:59:28 -04001144 * If the page isn't exclusively mapped into this vma,
1145 * we must use the _oldest_ possible anon_vma for the
1146 * page mapping!
Linus Torvaldsea900022010-04-12 12:44:29 -07001147 */
Andi Kleen4e1c1972010-09-22 12:43:56 +02001148 if (!exclusive)
Andrea Arcangeli288468c2010-08-09 17:19:09 -07001149 anon_vma = anon_vma->root;
Linus Torvaldsea900022010-04-12 12:44:29 -07001150
Nick Piggin9617d952006-01-06 00:11:12 -08001151 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1152 page->mapping = (struct address_space *) anon_vma;
Nick Piggin9617d952006-01-06 00:11:12 -08001153 page->index = linear_page_index(vma, address);
Nick Piggin9617d952006-01-06 00:11:12 -08001154}
1155
1156/**
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001157 * __page_check_anon_rmap - sanity check anonymous rmap addition
Nick Pigginc97a9e12007-05-16 22:11:21 -07001158 * @page: the page to add the mapping to
1159 * @vma: the vm area in which the mapping is added
1160 * @address: the user virtual address mapped
1161 */
1162static void __page_check_anon_rmap(struct page *page,
1163 struct vm_area_struct *vma, unsigned long address)
1164{
1165#ifdef CONFIG_DEBUG_VM
1166 /*
1167 * The page's anon-rmap details (mapping and index) are guaranteed to
1168 * be set up correctly at this point.
1169 *
1170 * We have exclusion against page_add_anon_rmap because the caller
1171 * always holds the page locked, except if called from page_dup_rmap,
1172 * in which case the page is already known to be setup.
1173 *
1174 * We have exclusion against page_add_new_anon_rmap because those pages
1175 * are initially only visible via the pagetables, and the pte is locked
1176 * over the call to page_add_new_anon_rmap.
1177 */
Andrea Arcangeli44ab57a2010-08-09 17:19:10 -07001178 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001179 BUG_ON(page_to_pgoff(page) != linear_page_index(vma, address));
Nick Pigginc97a9e12007-05-16 22:11:21 -07001180#endif
1181}
1182
1183/**
Linus Torvalds1da177e2005-04-16 15:20:36 -07001184 * page_add_anon_rmap - add pte mapping to an anonymous page
1185 * @page: the page to add the mapping to
1186 * @vma: the vm area in which the mapping is added
1187 * @address: the user virtual address mapped
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001188 * @compound: charge the page as compound or small page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001189 *
Hugh Dickins5ad64682009-12-14 17:59:24 -08001190 * The caller needs to hold the pte lock, and the page must be locked in
Hugh Dickins80e148222009-12-14 17:59:29 -08001191 * the anon_vma case: to serialize mapping,index checking after setting,
1192 * and to ensure that PageAnon is not being upgraded racily to PageKsm
1193 * (but PageKsm is never downgraded to PageAnon).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001194 */
1195void page_add_anon_rmap(struct page *page,
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001196 struct vm_area_struct *vma, unsigned long address, bool compound)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001197{
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001198 do_page_add_anon_rmap(page, vma, address, compound ? RMAP_COMPOUND : 0);
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001199}
1200
1201/*
1202 * Special version of the above for do_swap_page, which often runs
1203 * into pages that are exclusively owned by the current process.
1204 * Everybody else should continue to use page_add_anon_rmap above.
1205 */
1206void do_page_add_anon_rmap(struct page *page,
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001207 struct vm_area_struct *vma, unsigned long address, int flags)
Rik van Rielad8c2ee2010-08-09 17:19:48 -07001208{
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001209 bool compound = flags & RMAP_COMPOUND;
1210 bool first;
1211
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001212 if (compound) {
1213 atomic_t *mapcount;
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001214 VM_BUG_ON_PAGE(!PageLocked(page), page);
Kirill A. Shutemove9b61f12016-01-15 16:54:10 -08001215 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
1216 mapcount = compound_mapcount_ptr(page);
1217 first = atomic_inc_and_test(mapcount);
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001218 } else {
1219 first = atomic_inc_and_test(&page->_mapcount);
1220 }
1221
Andrea Arcangeli79134172011-01-13 15:46:58 -08001222 if (first) {
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001223 int nr = compound ? hpage_nr_pages(page) : 1;
Jianyu Zhanbea04b02014-06-04 16:09:51 -07001224 /*
1225 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1226 * these counters are not modified in interrupt context, and
1227 * pte lock(a spinlock) is held, which implies preemption
1228 * disabled.
1229 */
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001230 if (compound) {
Andrea Arcangeli79134172011-01-13 15:46:58 -08001231 __inc_zone_page_state(page,
1232 NR_ANON_TRANSPARENT_HUGEPAGES);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001233 }
1234 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, nr);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001235 }
Hugh Dickins5ad64682009-12-14 17:59:24 -08001236 if (unlikely(PageKsm(page)))
1237 return;
1238
Sasha Levin309381fea2014-01-23 15:52:54 -08001239 VM_BUG_ON_PAGE(!PageLocked(page), page);
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001240
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001241 /* address might be in next vma when migration races vma_adjust */
Hugh Dickins5ad64682009-12-14 17:59:24 -08001242 if (first)
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001243 __page_set_anon_rmap(page, vma, address,
1244 flags & RMAP_EXCLUSIVE);
KAMEZAWA Hiroyuki69029cd2008-07-25 01:47:14 -07001245 else
Nick Pigginc97a9e12007-05-16 22:11:21 -07001246 __page_check_anon_rmap(page, vma, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001247}
1248
Randy Dunlap43d8eac2008-03-19 17:00:43 -07001249/**
Nick Piggin9617d952006-01-06 00:11:12 -08001250 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1251 * @page: the page to add the mapping to
1252 * @vma: the vm area in which the mapping is added
1253 * @address: the user virtual address mapped
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001254 * @compound: charge the page as compound or small page
Nick Piggin9617d952006-01-06 00:11:12 -08001255 *
1256 * Same as page_add_anon_rmap but must only be called on *new* pages.
1257 * This means the inc-and-test can be bypassed.
Nick Pigginc97a9e12007-05-16 22:11:21 -07001258 * Page does not have to be locked.
Nick Piggin9617d952006-01-06 00:11:12 -08001259 */
1260void page_add_new_anon_rmap(struct page *page,
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001261 struct vm_area_struct *vma, unsigned long address, bool compound)
Nick Piggin9617d952006-01-06 00:11:12 -08001262{
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001263 int nr = compound ? hpage_nr_pages(page) : 1;
1264
Sasha Levin81d1b092014-10-09 15:28:10 -07001265 VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
Hugh Dickinscbf84b72009-01-06 14:39:27 -08001266 SetPageSwapBacked(page);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001267 if (compound) {
1268 VM_BUG_ON_PAGE(!PageTransHuge(page), page);
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001269 /* increment count (starts at -1) */
1270 atomic_set(compound_mapcount_ptr(page), 0);
Andrea Arcangeli79134172011-01-13 15:46:58 -08001271 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001272 } else {
1273 /* Anon THP always mapped first with PMD */
1274 VM_BUG_ON_PAGE(PageTransCompound(page), page);
1275 /* increment count (starts at -1) */
1276 atomic_set(&page->_mapcount, 0);
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001277 }
1278 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, nr);
Rik van Riele8a03fe2010-04-14 17:59:28 -04001279 __page_set_anon_rmap(page, vma, address, 1);
Nick Piggin9617d952006-01-06 00:11:12 -08001280}
1281
Linus Torvalds1da177e2005-04-16 15:20:36 -07001282/**
1283 * page_add_file_rmap - add pte mapping to a file page
1284 * @page: the page to add the mapping to
1285 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001286 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001287 */
1288void page_add_file_rmap(struct page *page)
1289{
Johannes Weiner62cccb82016-03-15 14:57:22 -07001290 lock_page_memcg(page);
Balbir Singhd69b0422009-06-17 16:26:34 -07001291 if (atomic_inc_and_test(&page->_mapcount)) {
Christoph Lameter65ba55f2006-06-30 01:55:34 -07001292 __inc_zone_page_state(page, NR_FILE_MAPPED);
Johannes Weiner62cccb82016-03-15 14:57:22 -07001293 mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
Balbir Singhd69b0422009-06-17 16:26:34 -07001294 }
Johannes Weiner62cccb82016-03-15 14:57:22 -07001295 unlock_page_memcg(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001296}
1297
Johannes Weiner8186eb62014-10-29 14:50:51 -07001298static void page_remove_file_rmap(struct page *page)
1299{
Johannes Weiner62cccb82016-03-15 14:57:22 -07001300 lock_page_memcg(page);
Johannes Weiner8186eb62014-10-29 14:50:51 -07001301
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001302 /* Hugepages are not counted in NR_FILE_MAPPED for now. */
1303 if (unlikely(PageHuge(page))) {
1304 /* hugetlb pages are always mapped with pmds */
1305 atomic_dec(compound_mapcount_ptr(page));
1306 goto out;
1307 }
1308
Johannes Weiner8186eb62014-10-29 14:50:51 -07001309 /* page still mapped by someone else? */
1310 if (!atomic_add_negative(-1, &page->_mapcount))
1311 goto out;
1312
Johannes Weiner8186eb62014-10-29 14:50:51 -07001313 /*
1314 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1315 * these counters are not modified in interrupt context, and
1316 * pte lock(a spinlock) is held, which implies preemption disabled.
1317 */
1318 __dec_zone_page_state(page, NR_FILE_MAPPED);
Johannes Weiner62cccb82016-03-15 14:57:22 -07001319 mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
Johannes Weiner8186eb62014-10-29 14:50:51 -07001320
1321 if (unlikely(PageMlocked(page)))
1322 clear_page_mlock(page);
1323out:
Johannes Weiner62cccb82016-03-15 14:57:22 -07001324 unlock_page_memcg(page);
Johannes Weiner8186eb62014-10-29 14:50:51 -07001325}
1326
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001327static void page_remove_anon_compound_rmap(struct page *page)
1328{
1329 int i, nr;
1330
1331 if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
1332 return;
1333
1334 /* Hugepages are not counted in NR_ANON_PAGES for now. */
1335 if (unlikely(PageHuge(page)))
1336 return;
1337
1338 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1339 return;
1340
1341 __dec_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
1342
1343 if (TestClearPageDoubleMap(page)) {
1344 /*
1345 * Subpages can be mapped with PTEs too. Check how many of
1346 * themi are still mapped.
1347 */
1348 for (i = 0, nr = 0; i < HPAGE_PMD_NR; i++) {
1349 if (atomic_add_negative(-1, &page[i]._mapcount))
1350 nr++;
1351 }
1352 } else {
1353 nr = HPAGE_PMD_NR;
1354 }
1355
Kirill A. Shutemove90309c2016-01-15 16:54:33 -08001356 if (unlikely(PageMlocked(page)))
1357 clear_page_mlock(page);
1358
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08001359 if (nr) {
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001360 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, -nr);
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08001361 deferred_split_huge_page(page);
1362 }
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001363}
1364
Linus Torvalds1da177e2005-04-16 15:20:36 -07001365/**
1366 * page_remove_rmap - take down pte mapping from a page
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001367 * @page: page to remove mapping from
1368 * @compound: uncharge the page as compound or small page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001369 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -07001370 * The caller needs to hold the pte lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001371 */
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001372void page_remove_rmap(struct page *page, bool compound)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001373{
Johannes Weiner8186eb62014-10-29 14:50:51 -07001374 if (!PageAnon(page)) {
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001375 VM_BUG_ON_PAGE(compound && !PageHuge(page), page);
Johannes Weiner8186eb62014-10-29 14:50:51 -07001376 page_remove_file_rmap(page);
1377 return;
1378 }
KAMEZAWA Hiroyuki89c06bd2012-03-21 16:34:25 -07001379
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001380 if (compound)
1381 return page_remove_anon_compound_rmap(page);
1382
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001383 /* page still mapped by someone else? */
1384 if (!atomic_add_negative(-1, &page->_mapcount))
Johannes Weiner8186eb62014-10-29 14:50:51 -07001385 return;
1386
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001387 /*
Jianyu Zhanbea04b02014-06-04 16:09:51 -07001388 * We use the irq-unsafe __{inc|mod}_zone_page_stat because
1389 * these counters are not modified in interrupt context, and
Jianyu Zhanbea04b02014-06-04 16:09:51 -07001390 * pte lock(a spinlock) is held, which implies preemption disabled.
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001391 */
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001392 __dec_zone_page_state(page, NR_ANON_PAGES);
Johannes Weiner8186eb62014-10-29 14:50:51 -07001393
Hugh Dickinse6c509f2012-10-08 16:33:19 -07001394 if (unlikely(PageMlocked(page)))
1395 clear_page_mlock(page);
Johannes Weiner8186eb62014-10-29 14:50:51 -07001396
Kirill A. Shutemov9a982252016-01-15 16:54:17 -08001397 if (PageTransCompound(page))
1398 deferred_split_huge_page(compound_head(page));
1399
KOSAKI Motohirob904dcf2009-09-21 17:01:28 -07001400 /*
1401 * It would be tidy to reset the PageAnon mapping here,
1402 * but that might overwrite a racing page_add_anon_rmap
1403 * which increments mapcount after us but sets mapping
1404 * before us: so leave the reset to free_hot_cold_page,
1405 * and remember that it's only reliable while mapped.
1406 * Leaving it set also helps swapoff to reinstate ptes
1407 * faster for those pages still in swapcache.
1408 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07001409}
1410
Minchan Kim854e9ed2016-01-15 16:54:53 -08001411struct rmap_private {
1412 enum ttu_flags flags;
1413 int lazyfreed;
1414};
1415
Linus Torvalds1da177e2005-04-16 15:20:36 -07001416/*
Joonsoo Kim52629502014-01-21 15:49:50 -08001417 * @arg: enum ttu_flags will be passed to this argument
Linus Torvalds1da177e2005-04-16 15:20:36 -07001418 */
Kirill A. Shutemovac769502014-06-04 16:08:17 -07001419static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
Joonsoo Kim52629502014-01-21 15:49:50 -08001420 unsigned long address, void *arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001421{
1422 struct mm_struct *mm = vma->vm_mm;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001423 pte_t *pte;
1424 pte_t pteval;
Hugh Dickinsc0718802005-10-29 18:16:31 -07001425 spinlock_t *ptl;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426 int ret = SWAP_AGAIN;
Minchan Kim854e9ed2016-01-15 16:54:53 -08001427 struct rmap_private *rp = arg;
1428 enum ttu_flags flags = rp->flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001429
Hugh Dickinsb87537d9e2015-11-05 18:49:33 -08001430 /* munlock has nothing to gain from examining un-locked vmas */
1431 if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED))
1432 goto out;
1433
Nick Piggin479db0b2008-08-20 14:09:18 -07001434 pte = page_check_address(page, mm, address, &ptl, 0);
Hugh Dickinsc0718802005-10-29 18:16:31 -07001435 if (!pte)
Nikita Danilov81b40822005-05-01 08:58:36 -07001436 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001437
1438 /*
1439 * If the page is mlock()d, we cannot swap it out.
1440 * If it's recently referenced (perhaps page_referenced
1441 * skipped over this mm) then we should reactivate it.
1442 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001443 if (!(flags & TTU_IGNORE_MLOCK)) {
Hugh Dickinsb87537d9e2015-11-05 18:49:33 -08001444 if (vma->vm_flags & VM_LOCKED) {
1445 /* Holding pte lock, we do *not* need mmap_sem here */
1446 mlock_vma_page(page);
1447 ret = SWAP_MLOCK;
1448 goto out_unmap;
1449 }
Konstantin Khlebnikovdaa5ba72014-06-04 16:10:52 -07001450 if (flags & TTU_MUNLOCK)
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001451 goto out_unmap;
Andi Kleen14fa31b2009-09-16 11:50:10 +02001452 }
1453 if (!(flags & TTU_IGNORE_ACCESS)) {
Nick Pigginb291f002008-10-18 20:26:44 -07001454 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1455 ret = SWAP_FAIL;
1456 goto out_unmap;
1457 }
1458 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001459
Linus Torvalds1da177e2005-04-16 15:20:36 -07001460 /* Nuke the page table entry. */
1461 flush_cache_page(vma, address, page_to_pfn(page));
Mel Gorman72b252a2015-09-04 15:47:32 -07001462 if (should_defer_flush(mm, flags)) {
1463 /*
1464 * We clear the PTE but do not flush so potentially a remote
1465 * CPU could still be writing to the page. If the entry was
1466 * previously clean then the architecture must guarantee that
1467 * a clear->dirty transition on a cached TLB entry is written
1468 * through and traps if the PTE is unmapped.
1469 */
1470 pteval = ptep_get_and_clear(mm, address, pte);
1471
Mel Gormand950c942015-09-04 15:47:35 -07001472 set_tlb_ubc_flush_pending(mm, page, pte_dirty(pteval));
Mel Gorman72b252a2015-09-04 15:47:32 -07001473 } else {
1474 pteval = ptep_clear_flush(vma, address, pte);
1475 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001476
1477 /* Move the dirty bit to the physical page now the pte is gone. */
1478 if (pte_dirty(pteval))
1479 set_page_dirty(page);
1480
Hugh Dickins365e9c872005-10-29 18:16:18 -07001481 /* Update high watermark before we lower rss */
1482 update_hiwater_rss(mm);
1483
Andi Kleen888b9f72009-09-16 11:50:11 +02001484 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
Naoya Horiguchi5d317b22015-11-05 18:47:14 -08001485 if (PageHuge(page)) {
1486 hugetlb_count_sub(1 << compound_order(page), mm);
1487 } else {
Jerome Marchandeca56ff2016-01-14 15:19:26 -08001488 dec_mm_counter(mm, mm_counter(page));
Naoya Horiguchi5f24ae52012-12-12 13:52:30 -08001489 }
Andi Kleen888b9f72009-09-16 11:50:11 +02001490 set_pte_at(mm, address, pte,
Naoya Horiguchi5f24ae52012-12-12 13:52:30 -08001491 swp_entry_to_pte(make_hwpoison_entry(page)));
Konstantin Weitz45961722013-04-17 13:59:32 +02001492 } else if (pte_unused(pteval)) {
1493 /*
1494 * The guest indicated that the page content is of no
1495 * interest anymore. Simply discard the pte, vmscan
1496 * will take care of the rest.
1497 */
Jerome Marchandeca56ff2016-01-14 15:19:26 -08001498 dec_mm_counter(mm, mm_counter(page));
Hugh Dickins470f1192015-11-05 18:49:59 -08001499 } else if (IS_ENABLED(CONFIG_MIGRATION) && (flags & TTU_MIGRATION)) {
1500 swp_entry_t entry;
Cyrill Gorcunov179ef712013-08-13 16:00:49 -07001501 pte_t swp_pte;
Hugh Dickins470f1192015-11-05 18:49:59 -08001502 /*
1503 * Store the pfn of the page in a special migration
1504 * pte. do_swap_page() will wait until the migration
1505 * pte is removed and then restart fault handling.
1506 */
1507 entry = make_migration_entry(page, pte_write(pteval));
Cyrill Gorcunov179ef712013-08-13 16:00:49 -07001508 swp_pte = swp_entry_to_pte(entry);
1509 if (pte_soft_dirty(pteval))
1510 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1511 set_pte_at(mm, address, pte, swp_pte);
Hugh Dickins470f1192015-11-05 18:49:59 -08001512 } else if (PageAnon(page)) {
1513 swp_entry_t entry = { .val = page_private(page) };
1514 pte_t swp_pte;
1515 /*
1516 * Store the swap location in the pte.
1517 * See handle_pte_fault() ...
1518 */
1519 VM_BUG_ON_PAGE(!PageSwapCache(page), page);
Minchan Kim854e9ed2016-01-15 16:54:53 -08001520
1521 if (!PageDirty(page) && (flags & TTU_LZFREE)) {
1522 /* It's a freeable page by MADV_FREE */
1523 dec_mm_counter(mm, MM_ANONPAGES);
1524 rp->lazyfreed++;
1525 goto discard;
1526 }
1527
Hugh Dickins470f1192015-11-05 18:49:59 -08001528 if (swap_duplicate(entry) < 0) {
1529 set_pte_at(mm, address, pte, pteval);
1530 ret = SWAP_FAIL;
1531 goto out_unmap;
1532 }
1533 if (list_empty(&mm->mmlist)) {
1534 spin_lock(&mmlist_lock);
1535 if (list_empty(&mm->mmlist))
1536 list_add(&mm->mmlist, &init_mm.mmlist);
1537 spin_unlock(&mmlist_lock);
1538 }
1539 dec_mm_counter(mm, MM_ANONPAGES);
1540 inc_mm_counter(mm, MM_SWAPENTS);
1541 swp_pte = swp_entry_to_pte(entry);
1542 if (pte_soft_dirty(pteval))
1543 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1544 set_pte_at(mm, address, pte, swp_pte);
Christoph Lameter04e62a22006-06-23 02:03:38 -07001545 } else
Jerome Marchandeca56ff2016-01-14 15:19:26 -08001546 dec_mm_counter(mm, mm_counter_file(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001547
Minchan Kim854e9ed2016-01-15 16:54:53 -08001548discard:
Kirill A. Shutemovd281ee62016-01-15 16:52:16 -08001549 page_remove_rmap(page, PageHuge(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -07001550 page_cache_release(page);
1551
1552out_unmap:
Hugh Dickinsc0718802005-10-29 18:16:31 -07001553 pte_unmap_unlock(pte, ptl);
Hugh Dickinsb87537d9e2015-11-05 18:49:33 -08001554 if (ret != SWAP_FAIL && ret != SWAP_MLOCK && !(flags & TTU_MUNLOCK))
Sagi Grimberg2ec74c32012-10-08 16:33:33 -07001555 mmu_notifier_invalidate_page(mm, address);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001556out:
1557 return ret;
1558}
1559
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -08001560bool is_vma_temporary_stack(struct vm_area_struct *vma)
Mel Gormana8bef8ff2010-05-24 14:32:24 -07001561{
1562 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1563
1564 if (!maybe_stack)
1565 return false;
1566
1567 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1568 VM_STACK_INCOMPLETE_SETUP)
1569 return true;
1570
1571 return false;
1572}
1573
Joonsoo Kim52629502014-01-21 15:49:50 -08001574static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
1575{
1576 return is_vma_temporary_stack(vma);
1577}
1578
Joonsoo Kim52629502014-01-21 15:49:50 -08001579static int page_not_mapped(struct page *page)
1580{
1581 return !page_mapped(page);
1582};
1583
Linus Torvalds1da177e2005-04-16 15:20:36 -07001584/**
1585 * try_to_unmap - try to remove all page table mappings to a page
1586 * @page: the page to get unmapped
Andi Kleen14fa31b2009-09-16 11:50:10 +02001587 * @flags: action and flags
Linus Torvalds1da177e2005-04-16 15:20:36 -07001588 *
1589 * Tries to remove all the page table entries which are mapping this
1590 * page, used in the pageout path. Caller must hold the page lock.
1591 * Return values are:
1592 *
1593 * SWAP_SUCCESS - we succeeded in removing all mappings
1594 * SWAP_AGAIN - we missed a mapping, try again later
1595 * SWAP_FAIL - the page is unswappable
Nick Pigginb291f002008-10-18 20:26:44 -07001596 * SWAP_MLOCK - page is mlocked.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001597 */
Andi Kleen14fa31b2009-09-16 11:50:10 +02001598int try_to_unmap(struct page *page, enum ttu_flags flags)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001599{
1600 int ret;
Minchan Kim854e9ed2016-01-15 16:54:53 -08001601 struct rmap_private rp = {
1602 .flags = flags,
1603 .lazyfreed = 0,
1604 };
1605
Joonsoo Kim52629502014-01-21 15:49:50 -08001606 struct rmap_walk_control rwc = {
1607 .rmap_one = try_to_unmap_one,
Minchan Kim854e9ed2016-01-15 16:54:53 -08001608 .arg = &rp,
Joonsoo Kim52629502014-01-21 15:49:50 -08001609 .done = page_not_mapped,
Joonsoo Kim52629502014-01-21 15:49:50 -08001610 .anon_lock = page_lock_anon_vma_read,
1611 };
Linus Torvalds1da177e2005-04-16 15:20:36 -07001612
Sasha Levin309381fea2014-01-23 15:52:54 -08001613 VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001614
Joonsoo Kim52629502014-01-21 15:49:50 -08001615 /*
1616 * During exec, a temporary VMA is setup and later moved.
1617 * The VMA is moved under the anon_vma lock but not the
1618 * page tables leading to a race where migration cannot
1619 * find the migration ptes. Rather than increasing the
1620 * locking requirements of exec(), migration skips
1621 * temporary VMAs until after exec() completes.
1622 */
Konstantin Khlebnikovdaa5ba72014-06-04 16:10:52 -07001623 if ((flags & TTU_MIGRATION) && !PageKsm(page) && PageAnon(page))
Joonsoo Kim52629502014-01-21 15:49:50 -08001624 rwc.invalid_vma = invalid_migration_vma;
1625
1626 ret = rmap_walk(page, &rwc);
1627
Minchan Kim854e9ed2016-01-15 16:54:53 -08001628 if (ret != SWAP_MLOCK && !page_mapped(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001629 ret = SWAP_SUCCESS;
Minchan Kim854e9ed2016-01-15 16:54:53 -08001630 if (rp.lazyfreed && !PageDirty(page))
1631 ret = SWAP_LZFREE;
1632 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001633 return ret;
1634}
Nikita Danilov81b40822005-05-01 08:58:36 -07001635
Nick Pigginb291f002008-10-18 20:26:44 -07001636/**
1637 * try_to_munlock - try to munlock a page
1638 * @page: the page to be munlocked
1639 *
1640 * Called from munlock code. Checks all of the VMAs mapping the page
1641 * to make sure nobody else has this page mlocked. The page will be
1642 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1643 *
1644 * Return values are:
1645 *
Hugh Dickins53f79ac2009-12-14 17:58:58 -08001646 * SWAP_AGAIN - no vma is holding page mlocked, or,
Nick Pigginb291f002008-10-18 20:26:44 -07001647 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
Hugh Dickins5ad64682009-12-14 17:59:24 -08001648 * SWAP_FAIL - page cannot be located at present
Nick Pigginb291f002008-10-18 20:26:44 -07001649 * SWAP_MLOCK - page is now mlocked.
1650 */
1651int try_to_munlock(struct page *page)
1652{
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001653 int ret;
Minchan Kim854e9ed2016-01-15 16:54:53 -08001654 struct rmap_private rp = {
1655 .flags = TTU_MUNLOCK,
1656 .lazyfreed = 0,
1657 };
1658
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001659 struct rmap_walk_control rwc = {
1660 .rmap_one = try_to_unmap_one,
Minchan Kim854e9ed2016-01-15 16:54:53 -08001661 .arg = &rp,
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001662 .done = page_not_mapped,
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001663 .anon_lock = page_lock_anon_vma_read,
1664
1665 };
1666
Sasha Levin309381fea2014-01-23 15:52:54 -08001667 VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
Nick Pigginb291f002008-10-18 20:26:44 -07001668
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001669 ret = rmap_walk(page, &rwc);
1670 return ret;
Nick Pigginb291f002008-10-18 20:26:44 -07001671}
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001672
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001673void __put_anon_vma(struct anon_vma *anon_vma)
Rik van Riel76545062010-08-09 17:18:41 -07001674{
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001675 struct anon_vma *root = anon_vma->root;
Rik van Riel76545062010-08-09 17:18:41 -07001676
Andrey Ryabinin624483f2014-06-06 19:09:30 +04001677 anon_vma_free(anon_vma);
Peter Zijlstra01d8b202011-03-22 16:32:49 -07001678 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1679 anon_vma_free(root);
Rik van Riel76545062010-08-09 17:18:41 -07001680}
Rik van Riel76545062010-08-09 17:18:41 -07001681
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001682static struct anon_vma *rmap_walk_anon_lock(struct page *page,
1683 struct rmap_walk_control *rwc)
Joonsoo Kimfaecd8d2014-01-21 15:49:46 -08001684{
1685 struct anon_vma *anon_vma;
1686
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001687 if (rwc->anon_lock)
1688 return rwc->anon_lock(page);
1689
Joonsoo Kimfaecd8d2014-01-21 15:49:46 -08001690 /*
1691 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
1692 * because that depends on page_mapped(); but not all its usages
1693 * are holding mmap_sem. Users without mmap_sem are required to
1694 * take a reference count to prevent the anon_vma disappearing
1695 */
1696 anon_vma = page_anon_vma(page);
1697 if (!anon_vma)
1698 return NULL;
1699
1700 anon_vma_lock_read(anon_vma);
1701 return anon_vma;
1702}
1703
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001704/*
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001705 * rmap_walk_anon - do something to anonymous page using the object-based
1706 * rmap method
1707 * @page: the page to be handled
1708 * @rwc: control variable according to each walk type
1709 *
1710 * Find all the mappings of a page using the mapping pointer and the vma chains
1711 * contained in the anon_vma struct it points to.
1712 *
1713 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1714 * where the page was found will be held for write. So, we won't recheck
1715 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1716 * LOCKED.
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001717 */
Joonsoo Kim051ac832014-01-21 15:49:48 -08001718static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001719{
1720 struct anon_vma *anon_vma;
Davidlohr Buesob258d862014-12-12 16:55:04 -08001721 pgoff_t pgoff;
Rik van Riel5beb4932010-03-05 13:42:07 -08001722 struct anon_vma_chain *avc;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001723 int ret = SWAP_AGAIN;
1724
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001725 anon_vma = rmap_walk_anon_lock(page, rwc);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001726 if (!anon_vma)
1727 return ret;
Joonsoo Kimfaecd8d2014-01-21 15:49:46 -08001728
Davidlohr Buesob258d862014-12-12 16:55:04 -08001729 pgoff = page_to_pgoff(page);
Michel Lespinassebf181b92012-10-08 16:31:39 -07001730 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
Rik van Riel5beb4932010-03-05 13:42:07 -08001731 struct vm_area_struct *vma = avc->vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001732 unsigned long address = vma_address(page, vma);
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001733
Andrea Arcangeliad126952015-11-05 18:49:07 -08001734 cond_resched();
1735
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001736 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1737 continue;
1738
Joonsoo Kim051ac832014-01-21 15:49:48 -08001739 ret = rwc->rmap_one(page, vma, address, rwc->arg);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001740 if (ret != SWAP_AGAIN)
1741 break;
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001742 if (rwc->done && rwc->done(page))
1743 break;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001744 }
Ingo Molnar4fc3f1d2012-12-02 19:56:50 +00001745 anon_vma_unlock_read(anon_vma);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001746 return ret;
1747}
1748
Joonsoo Kime8351ac2014-01-21 15:49:52 -08001749/*
1750 * rmap_walk_file - do something to file page using the object-based rmap method
1751 * @page: the page to be handled
1752 * @rwc: control variable according to each walk type
1753 *
1754 * Find all the mappings of a page using the mapping pointer and the vma chains
1755 * contained in the address_space struct it points to.
1756 *
1757 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1758 * where the page was found will be held for write. So, we won't recheck
1759 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1760 * LOCKED.
1761 */
Joonsoo Kim051ac832014-01-21 15:49:48 -08001762static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001763{
1764 struct address_space *mapping = page->mapping;
Davidlohr Buesob258d862014-12-12 16:55:04 -08001765 pgoff_t pgoff;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001766 struct vm_area_struct *vma;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001767 int ret = SWAP_AGAIN;
1768
Joonsoo Kim9f326242014-01-21 15:49:53 -08001769 /*
1770 * The page lock not only makes sure that page->mapping cannot
1771 * suddenly be NULLified by truncation, it makes sure that the
1772 * structure at mapping cannot be freed and reused yet,
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -08001773 * so we can safely take mapping->i_mmap_rwsem.
Joonsoo Kim9f326242014-01-21 15:49:53 -08001774 */
Sasha Levin81d1b092014-10-09 15:28:10 -07001775 VM_BUG_ON_PAGE(!PageLocked(page), page);
Joonsoo Kim9f326242014-01-21 15:49:53 -08001776
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001777 if (!mapping)
1778 return ret;
Davidlohr Bueso3dec0ba2014-12-12 16:54:27 -08001779
Davidlohr Buesob258d862014-12-12 16:55:04 -08001780 pgoff = page_to_pgoff(page);
Davidlohr Bueso3dec0ba2014-12-12 16:54:27 -08001781 i_mmap_lock_read(mapping);
Michel Lespinasse6b2dbba2012-10-08 16:31:25 -07001782 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001783 unsigned long address = vma_address(page, vma);
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001784
Andrea Arcangeliad126952015-11-05 18:49:07 -08001785 cond_resched();
1786
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001787 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1788 continue;
1789
Joonsoo Kim051ac832014-01-21 15:49:48 -08001790 ret = rwc->rmap_one(page, vma, address, rwc->arg);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001791 if (ret != SWAP_AGAIN)
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001792 goto done;
1793 if (rwc->done && rwc->done(page))
1794 goto done;
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001795 }
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001796
Joonsoo Kim0dd1c7b2014-01-21 15:49:49 -08001797done:
Davidlohr Bueso3dec0ba2014-12-12 16:54:27 -08001798 i_mmap_unlock_read(mapping);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001799 return ret;
1800}
1801
Joonsoo Kim051ac832014-01-21 15:49:48 -08001802int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001803{
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001804 if (unlikely(PageKsm(page)))
Joonsoo Kim051ac832014-01-21 15:49:48 -08001805 return rmap_walk_ksm(page, rwc);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001806 else if (PageAnon(page))
Joonsoo Kim051ac832014-01-21 15:49:48 -08001807 return rmap_walk_anon(page, rwc);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001808 else
Joonsoo Kim051ac832014-01-21 15:49:48 -08001809 return rmap_walk_file(page, rwc);
Hugh Dickinse9995ef2009-12-14 17:59:31 -08001810}
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001811
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001812#ifdef CONFIG_HUGETLB_PAGE
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001813/*
1814 * The following three functions are for anonymous (private mapped) hugepages.
1815 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1816 * and no lru code, because we handle hugepages differently from common pages.
1817 */
1818static void __hugepage_set_anon_rmap(struct page *page,
1819 struct vm_area_struct *vma, unsigned long address, int exclusive)
1820{
1821 struct anon_vma *anon_vma = vma->anon_vma;
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001822
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001823 BUG_ON(!anon_vma);
Naoya Horiguchi433abed2010-09-10 13:23:03 +09001824
1825 if (PageAnon(page))
1826 return;
1827 if (!exclusive)
1828 anon_vma = anon_vma->root;
1829
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001830 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1831 page->mapping = (struct address_space *) anon_vma;
1832 page->index = linear_page_index(vma, address);
1833}
1834
1835void hugepage_add_anon_rmap(struct page *page,
1836 struct vm_area_struct *vma, unsigned long address)
1837{
1838 struct anon_vma *anon_vma = vma->anon_vma;
1839 int first;
Naoya Horiguchia850ea32010-09-10 13:23:06 +09001840
1841 BUG_ON(!PageLocked(page));
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001842 BUG_ON(!anon_vma);
Hugh Dickins5dbe0af2011-05-28 13:17:04 -07001843 /* address might be in next vma when migration races vma_adjust */
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001844 first = atomic_inc_and_test(compound_mapcount_ptr(page));
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001845 if (first)
1846 __hugepage_set_anon_rmap(page, vma, address, 0);
1847}
1848
1849void hugepage_add_new_anon_rmap(struct page *page,
1850 struct vm_area_struct *vma, unsigned long address)
1851{
1852 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
Kirill A. Shutemov53f92632016-01-15 16:53:42 -08001853 atomic_set(compound_mapcount_ptr(page), 0);
Naoya Horiguchi0fe6e202010-05-28 09:29:16 +09001854 __hugepage_set_anon_rmap(page, vma, address, 1);
1855}
Naoya Horiguchie3390f62010-06-15 13:18:13 +09001856#endif /* CONFIG_HUGETLB_PAGE */