Eric Lee / smarc-ti-linux-kernel

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Commit f915a1cc754e3b82f238b64c69ad153e9be012c4

Authored by Dan Murphy
2 parents 95b4a088e7 624483f3ea
Exists in ti-linux-3.15.y and in 1 other branch smarc-ti-linux-3.15.y

Merge branch 'master' of http://git.kernel.org/pub/scm/linux/kernel/git/torvalds… 

…/linux into ti-linux-3.15.y

* 'master' of http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux:
  mm: rmap: fix use-after-free in __put_anon_vma

Signed-off-by: Dan Murphy <DMurphy@ti.com>

Showing 1 changed file Inline Diff

1 /* 1 /*
2 * mm/rmap.c - physical to virtual reverse mappings 2 * mm/rmap.c - physical to virtual reverse mappings
3 * 3 *
4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br> 4 * Copyright 2001, Rik van Riel <riel@conectiva.com.br>
5 * Released under the General Public License (GPL). 5 * Released under the General Public License (GPL).
6 * 6 *
7 * Simple, low overhead reverse mapping scheme. 7 * Simple, low overhead reverse mapping scheme.
8 * Please try to keep this thing as modular as possible. 8 * Please try to keep this thing as modular as possible.
9 * 9 *
10 * Provides methods for unmapping each kind of mapped page: 10 * Provides methods for unmapping each kind of mapped page:
11 * the anon methods track anonymous pages, and 11 * the anon methods track anonymous pages, and
12 * the file methods track pages belonging to an inode. 12 * the file methods track pages belonging to an inode.
13 * 13 *
14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001 14 * Original design by Rik van Riel <riel@conectiva.com.br> 2001
15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 15 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 16 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
17 * Contributions by Hugh Dickins 2003, 2004 17 * Contributions by Hugh Dickins 2003, 2004
18 */ 18 */
19 19
20 /* 20 /*
21 * Lock ordering in mm: 21 * Lock ordering in mm:
22 * 22 *
23 * inode->i_mutex (while writing or truncating, not reading or faulting) 23 * inode->i_mutex (while writing or truncating, not reading or faulting)
24 * mm->mmap_sem 24 * mm->mmap_sem
25 * page->flags PG_locked (lock_page) 25 * page->flags PG_locked (lock_page)
26 * mapping->i_mmap_mutex 26 * mapping->i_mmap_mutex
27 * anon_vma->rwsem 27 * anon_vma->rwsem
28 * mm->page_table_lock or pte_lock 28 * mm->page_table_lock or pte_lock
29 * zone->lru_lock (in mark_page_accessed, isolate_lru_page) 29 * zone->lru_lock (in mark_page_accessed, isolate_lru_page)
30 * swap_lock (in swap_duplicate, swap_info_get) 30 * swap_lock (in swap_duplicate, swap_info_get)
31 * mmlist_lock (in mmput, drain_mmlist and others) 31 * mmlist_lock (in mmput, drain_mmlist and others)
32 * mapping->private_lock (in __set_page_dirty_buffers) 32 * mapping->private_lock (in __set_page_dirty_buffers)
33 * inode->i_lock (in set_page_dirty's __mark_inode_dirty) 33 * inode->i_lock (in set_page_dirty's __mark_inode_dirty)
34 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) 34 * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty)
35 * sb_lock (within inode_lock in fs/fs-writeback.c) 35 * sb_lock (within inode_lock in fs/fs-writeback.c)
36 * mapping->tree_lock (widely used, in set_page_dirty, 36 * mapping->tree_lock (widely used, in set_page_dirty,
37 * in arch-dependent flush_dcache_mmap_lock, 37 * in arch-dependent flush_dcache_mmap_lock,
38 * within bdi.wb->list_lock in __sync_single_inode) 38 * within bdi.wb->list_lock in __sync_single_inode)
39 * 39 *
40 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon) 40 * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon)
41 * ->tasklist_lock 41 * ->tasklist_lock
42 * pte map lock 42 * pte map lock
43 */ 43 */
44 44
45 #include <linux/mm.h> 45 #include <linux/mm.h>
46 #include <linux/pagemap.h> 46 #include <linux/pagemap.h>
47 #include <linux/swap.h> 47 #include <linux/swap.h>
48 #include <linux/swapops.h> 48 #include <linux/swapops.h>
49 #include <linux/slab.h> 49 #include <linux/slab.h>
50 #include <linux/init.h> 50 #include <linux/init.h>
51 #include <linux/ksm.h> 51 #include <linux/ksm.h>
52 #include <linux/rmap.h> 52 #include <linux/rmap.h>
53 #include <linux/rcupdate.h> 53 #include <linux/rcupdate.h>
54 #include <linux/export.h> 54 #include <linux/export.h>
55 #include <linux/memcontrol.h> 55 #include <linux/memcontrol.h>
56 #include <linux/mmu_notifier.h> 56 #include <linux/mmu_notifier.h>
57 #include <linux/migrate.h> 57 #include <linux/migrate.h>
58 #include <linux/hugetlb.h> 58 #include <linux/hugetlb.h>
59 #include <linux/backing-dev.h> 59 #include <linux/backing-dev.h>
60 60
61 #include <asm/tlbflush.h> 61 #include <asm/tlbflush.h>
62 62
63 #include "internal.h" 63 #include "internal.h"
64 64
65 static struct kmem_cache *anon_vma_cachep; 65 static struct kmem_cache *anon_vma_cachep;
66 static struct kmem_cache *anon_vma_chain_cachep; 66 static struct kmem_cache *anon_vma_chain_cachep;
67 67
68 static inline struct anon_vma *anon_vma_alloc(void) 68 static inline struct anon_vma *anon_vma_alloc(void)
69 { 69 {
70 struct anon_vma *anon_vma; 70 struct anon_vma *anon_vma;
71 71
72 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); 72 anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
73 if (anon_vma) { 73 if (anon_vma) {
74 atomic_set(&anon_vma->refcount, 1); 74 atomic_set(&anon_vma->refcount, 1);
75 /* 75 /*
76 * Initialise the anon_vma root to point to itself. If called 76 * Initialise the anon_vma root to point to itself. If called
77 * from fork, the root will be reset to the parents anon_vma. 77 * from fork, the root will be reset to the parents anon_vma.
78 */ 78 */
79 anon_vma->root = anon_vma; 79 anon_vma->root = anon_vma;
80 } 80 }
81 81
82 return anon_vma; 82 return anon_vma;
83 } 83 }
84 84
85 static inline void anon_vma_free(struct anon_vma *anon_vma) 85 static inline void anon_vma_free(struct anon_vma *anon_vma)
86 { 86 {
87 VM_BUG_ON(atomic_read(&anon_vma->refcount)); 87 VM_BUG_ON(atomic_read(&anon_vma->refcount));
88 88
89 /* 89 /*
90 * Synchronize against page_lock_anon_vma_read() such that 90 * Synchronize against page_lock_anon_vma_read() such that
91 * we can safely hold the lock without the anon_vma getting 91 * we can safely hold the lock without the anon_vma getting
92 * freed. 92 * freed.
93 * 93 *
94 * Relies on the full mb implied by the atomic_dec_and_test() from 94 * Relies on the full mb implied by the atomic_dec_and_test() from
95 * put_anon_vma() against the acquire barrier implied by 95 * put_anon_vma() against the acquire barrier implied by
96 * down_read_trylock() from page_lock_anon_vma_read(). This orders: 96 * down_read_trylock() from page_lock_anon_vma_read(). This orders:
97 * 97 *
98 * page_lock_anon_vma_read() VS put_anon_vma() 98 * page_lock_anon_vma_read() VS put_anon_vma()
99 * down_read_trylock() atomic_dec_and_test() 99 * down_read_trylock() atomic_dec_and_test()
100 * LOCK MB 100 * LOCK MB
101 * atomic_read() rwsem_is_locked() 101 * atomic_read() rwsem_is_locked()
102 * 102 *
103 * LOCK should suffice since the actual taking of the lock must 103 * LOCK should suffice since the actual taking of the lock must
104 * happen _before_ what follows. 104 * happen _before_ what follows.
105 */ 105 */
106 if (rwsem_is_locked(&anon_vma->root->rwsem)) { 106 if (rwsem_is_locked(&anon_vma->root->rwsem)) {
107 anon_vma_lock_write(anon_vma); 107 anon_vma_lock_write(anon_vma);
108 anon_vma_unlock_write(anon_vma); 108 anon_vma_unlock_write(anon_vma);
109 } 109 }
110 110
111 kmem_cache_free(anon_vma_cachep, anon_vma); 111 kmem_cache_free(anon_vma_cachep, anon_vma);
112 } 112 }
113 113
114 static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp) 114 static inline struct anon_vma_chain *anon_vma_chain_alloc(gfp_t gfp)
115 { 115 {
116 return kmem_cache_alloc(anon_vma_chain_cachep, gfp); 116 return kmem_cache_alloc(anon_vma_chain_cachep, gfp);
117 } 117 }
118 118
119 static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) 119 static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain)
120 { 120 {
121 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); 121 kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain);
122 } 122 }
123 123
124 static void anon_vma_chain_link(struct vm_area_struct *vma, 124 static void anon_vma_chain_link(struct vm_area_struct *vma,
125 struct anon_vma_chain *avc, 125 struct anon_vma_chain *avc,
126 struct anon_vma *anon_vma) 126 struct anon_vma *anon_vma)
127 { 127 {
128 avc->vma = vma; 128 avc->vma = vma;
129 avc->anon_vma = anon_vma; 129 avc->anon_vma = anon_vma;
130 list_add(&avc->same_vma, &vma->anon_vma_chain); 130 list_add(&avc->same_vma, &vma->anon_vma_chain);
131 anon_vma_interval_tree_insert(avc, &anon_vma->rb_root); 131 anon_vma_interval_tree_insert(avc, &anon_vma->rb_root);
132 } 132 }
133 133
134 /** 134 /**
135 * anon_vma_prepare - attach an anon_vma to a memory region 135 * anon_vma_prepare - attach an anon_vma to a memory region
136 * @vma: the memory region in question 136 * @vma: the memory region in question
137 * 137 *
138 * This makes sure the memory mapping described by 'vma' has 138 * This makes sure the memory mapping described by 'vma' has
139 * an 'anon_vma' attached to it, so that we can associate the 139 * an 'anon_vma' attached to it, so that we can associate the
140 * anonymous pages mapped into it with that anon_vma. 140 * anonymous pages mapped into it with that anon_vma.
141 * 141 *
142 * The common case will be that we already have one, but if 142 * The common case will be that we already have one, but if
143 * not we either need to find an adjacent mapping that we 143 * not we either need to find an adjacent mapping that we
144 * can re-use the anon_vma from (very common when the only 144 * can re-use the anon_vma from (very common when the only
145 * reason for splitting a vma has been mprotect()), or we 145 * reason for splitting a vma has been mprotect()), or we
146 * allocate a new one. 146 * allocate a new one.
147 * 147 *
148 * Anon-vma allocations are very subtle, because we may have 148 * Anon-vma allocations are very subtle, because we may have
149 * optimistically looked up an anon_vma in page_lock_anon_vma_read() 149 * optimistically looked up an anon_vma in page_lock_anon_vma_read()
150 * and that may actually touch the spinlock even in the newly 150 * and that may actually touch the spinlock even in the newly
151 * allocated vma (it depends on RCU to make sure that the 151 * allocated vma (it depends on RCU to make sure that the
152 * anon_vma isn't actually destroyed). 152 * anon_vma isn't actually destroyed).
153 * 153 *
154 * As a result, we need to do proper anon_vma locking even 154 * As a result, we need to do proper anon_vma locking even
155 * for the new allocation. At the same time, we do not want 155 * for the new allocation. At the same time, we do not want
156 * to do any locking for the common case of already having 156 * to do any locking for the common case of already having
157 * an anon_vma. 157 * an anon_vma.
158 * 158 *
159 * This must be called with the mmap_sem held for reading. 159 * This must be called with the mmap_sem held for reading.
160 */ 160 */
161 int anon_vma_prepare(struct vm_area_struct *vma) 161 int anon_vma_prepare(struct vm_area_struct *vma)
162 { 162 {
163 struct anon_vma *anon_vma = vma->anon_vma; 163 struct anon_vma *anon_vma = vma->anon_vma;
164 struct anon_vma_chain *avc; 164 struct anon_vma_chain *avc;
165 165
166 might_sleep(); 166 might_sleep();
167 if (unlikely(!anon_vma)) { 167 if (unlikely(!anon_vma)) {
168 struct mm_struct *mm = vma->vm_mm; 168 struct mm_struct *mm = vma->vm_mm;
169 struct anon_vma *allocated; 169 struct anon_vma *allocated;
170 170
171 avc = anon_vma_chain_alloc(GFP_KERNEL); 171 avc = anon_vma_chain_alloc(GFP_KERNEL);
172 if (!avc) 172 if (!avc)
173 goto out_enomem; 173 goto out_enomem;
174 174
175 anon_vma = find_mergeable_anon_vma(vma); 175 anon_vma = find_mergeable_anon_vma(vma);
176 allocated = NULL; 176 allocated = NULL;
177 if (!anon_vma) { 177 if (!anon_vma) {
178 anon_vma = anon_vma_alloc(); 178 anon_vma = anon_vma_alloc();
179 if (unlikely(!anon_vma)) 179 if (unlikely(!anon_vma))
180 goto out_enomem_free_avc; 180 goto out_enomem_free_avc;
181 allocated = anon_vma; 181 allocated = anon_vma;
182 } 182 }
183 183
184 anon_vma_lock_write(anon_vma); 184 anon_vma_lock_write(anon_vma);
185 /* page_table_lock to protect against threads */ 185 /* page_table_lock to protect against threads */
186 spin_lock(&mm->page_table_lock); 186 spin_lock(&mm->page_table_lock);
187 if (likely(!vma->anon_vma)) { 187 if (likely(!vma->anon_vma)) {
188 vma->anon_vma = anon_vma; 188 vma->anon_vma = anon_vma;
189 anon_vma_chain_link(vma, avc, anon_vma); 189 anon_vma_chain_link(vma, avc, anon_vma);
190 allocated = NULL; 190 allocated = NULL;
191 avc = NULL; 191 avc = NULL;
192 } 192 }
193 spin_unlock(&mm->page_table_lock); 193 spin_unlock(&mm->page_table_lock);
194 anon_vma_unlock_write(anon_vma); 194 anon_vma_unlock_write(anon_vma);
195 195
196 if (unlikely(allocated)) 196 if (unlikely(allocated))
197 put_anon_vma(allocated); 197 put_anon_vma(allocated);
198 if (unlikely(avc)) 198 if (unlikely(avc))
199 anon_vma_chain_free(avc); 199 anon_vma_chain_free(avc);
200 } 200 }
201 return 0; 201 return 0;
202 202
203 out_enomem_free_avc: 203 out_enomem_free_avc:
204 anon_vma_chain_free(avc); 204 anon_vma_chain_free(avc);
205 out_enomem: 205 out_enomem:
206 return -ENOMEM; 206 return -ENOMEM;
207 } 207 }
208 208
209 /* 209 /*
210 * This is a useful helper function for locking the anon_vma root as 210 * This is a useful helper function for locking the anon_vma root as
211 * we traverse the vma->anon_vma_chain, looping over anon_vma's that 211 * we traverse the vma->anon_vma_chain, looping over anon_vma's that
212 * have the same vma. 212 * have the same vma.
213 * 213 *
214 * Such anon_vma's should have the same root, so you'd expect to see 214 * Such anon_vma's should have the same root, so you'd expect to see
215 * just a single mutex_lock for the whole traversal. 215 * just a single mutex_lock for the whole traversal.
216 */ 216 */
217 static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma) 217 static inline struct anon_vma *lock_anon_vma_root(struct anon_vma *root, struct anon_vma *anon_vma)
218 { 218 {
219 struct anon_vma *new_root = anon_vma->root; 219 struct anon_vma *new_root = anon_vma->root;
220 if (new_root != root) { 220 if (new_root != root) {
221 if (WARN_ON_ONCE(root)) 221 if (WARN_ON_ONCE(root))
222 up_write(&root->rwsem); 222 up_write(&root->rwsem);
223 root = new_root; 223 root = new_root;
224 down_write(&root->rwsem); 224 down_write(&root->rwsem);
225 } 225 }
226 return root; 226 return root;
227 } 227 }
228 228
229 static inline void unlock_anon_vma_root(struct anon_vma *root) 229 static inline void unlock_anon_vma_root(struct anon_vma *root)
230 { 230 {
231 if (root) 231 if (root)
232 up_write(&root->rwsem); 232 up_write(&root->rwsem);
233 } 233 }
234 234
235 /* 235 /*
236 * Attach the anon_vmas from src to dst. 236 * Attach the anon_vmas from src to dst.
237 * Returns 0 on success, -ENOMEM on failure. 237 * Returns 0 on success, -ENOMEM on failure.
238 */ 238 */
239 int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) 239 int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src)
240 { 240 {
241 struct anon_vma_chain *avc, *pavc; 241 struct anon_vma_chain *avc, *pavc;
242 struct anon_vma *root = NULL; 242 struct anon_vma *root = NULL;
243 243
244 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { 244 list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
245 struct anon_vma *anon_vma; 245 struct anon_vma *anon_vma;
246 246
247 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN); 247 avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
248 if (unlikely(!avc)) { 248 if (unlikely(!avc)) {
249 unlock_anon_vma_root(root); 249 unlock_anon_vma_root(root);
250 root = NULL; 250 root = NULL;
251 avc = anon_vma_chain_alloc(GFP_KERNEL); 251 avc = anon_vma_chain_alloc(GFP_KERNEL);
252 if (!avc) 252 if (!avc)
253 goto enomem_failure; 253 goto enomem_failure;
254 } 254 }
255 anon_vma = pavc->anon_vma; 255 anon_vma = pavc->anon_vma;
256 root = lock_anon_vma_root(root, anon_vma); 256 root = lock_anon_vma_root(root, anon_vma);
257 anon_vma_chain_link(dst, avc, anon_vma); 257 anon_vma_chain_link(dst, avc, anon_vma);
258 } 258 }
259 unlock_anon_vma_root(root); 259 unlock_anon_vma_root(root);
260 return 0; 260 return 0;
261 261
262 enomem_failure: 262 enomem_failure:
263 unlink_anon_vmas(dst); 263 unlink_anon_vmas(dst);
264 return -ENOMEM; 264 return -ENOMEM;
265 } 265 }
266 266
267 /* 267 /*
268 * Attach vma to its own anon_vma, as well as to the anon_vmas that 268 * Attach vma to its own anon_vma, as well as to the anon_vmas that
269 * the corresponding VMA in the parent process is attached to. 269 * the corresponding VMA in the parent process is attached to.
270 * Returns 0 on success, non-zero on failure. 270 * Returns 0 on success, non-zero on failure.
271 */ 271 */
272 int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) 272 int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma)
273 { 273 {
274 struct anon_vma_chain *avc; 274 struct anon_vma_chain *avc;
275 struct anon_vma *anon_vma; 275 struct anon_vma *anon_vma;
276 276
277 /* Don't bother if the parent process has no anon_vma here. */ 277 /* Don't bother if the parent process has no anon_vma here. */
278 if (!pvma->anon_vma) 278 if (!pvma->anon_vma)
279 return 0; 279 return 0;
280 280
281 /* 281 /*
282 * First, attach the new VMA to the parent VMA's anon_vmas, 282 * First, attach the new VMA to the parent VMA's anon_vmas,
283 * so rmap can find non-COWed pages in child processes. 283 * so rmap can find non-COWed pages in child processes.
284 */ 284 */
285 if (anon_vma_clone(vma, pvma)) 285 if (anon_vma_clone(vma, pvma))
286 return -ENOMEM; 286 return -ENOMEM;
287 287
288 /* Then add our own anon_vma. */ 288 /* Then add our own anon_vma. */
289 anon_vma = anon_vma_alloc(); 289 anon_vma = anon_vma_alloc();
290 if (!anon_vma) 290 if (!anon_vma)
291 goto out_error; 291 goto out_error;
292 avc = anon_vma_chain_alloc(GFP_KERNEL); 292 avc = anon_vma_chain_alloc(GFP_KERNEL);
293 if (!avc) 293 if (!avc)
294 goto out_error_free_anon_vma; 294 goto out_error_free_anon_vma;
295 295
296 /* 296 /*
297 * The root anon_vma's spinlock is the lock actually used when we 297 * The root anon_vma's spinlock is the lock actually used when we
298 * lock any of the anon_vmas in this anon_vma tree. 298 * lock any of the anon_vmas in this anon_vma tree.
299 */ 299 */
300 anon_vma->root = pvma->anon_vma->root; 300 anon_vma->root = pvma->anon_vma->root;
301 /* 301 /*
302 * With refcounts, an anon_vma can stay around longer than the 302 * With refcounts, an anon_vma can stay around longer than the
303 * process it belongs to. The root anon_vma needs to be pinned until 303 * process it belongs to. The root anon_vma needs to be pinned until
304 * this anon_vma is freed, because the lock lives in the root. 304 * this anon_vma is freed, because the lock lives in the root.
305 */ 305 */
306 get_anon_vma(anon_vma->root); 306 get_anon_vma(anon_vma->root);
307 /* Mark this anon_vma as the one where our new (COWed) pages go. */ 307 /* Mark this anon_vma as the one where our new (COWed) pages go. */
308 vma->anon_vma = anon_vma; 308 vma->anon_vma = anon_vma;
309 anon_vma_lock_write(anon_vma); 309 anon_vma_lock_write(anon_vma);
310 anon_vma_chain_link(vma, avc, anon_vma); 310 anon_vma_chain_link(vma, avc, anon_vma);
311 anon_vma_unlock_write(anon_vma); 311 anon_vma_unlock_write(anon_vma);
312 312
313 return 0; 313 return 0;
314 314
315 out_error_free_anon_vma: 315 out_error_free_anon_vma:
316 put_anon_vma(anon_vma); 316 put_anon_vma(anon_vma);
317 out_error: 317 out_error:
318 unlink_anon_vmas(vma); 318 unlink_anon_vmas(vma);
319 return -ENOMEM; 319 return -ENOMEM;
320 } 320 }
321 321
322 void unlink_anon_vmas(struct vm_area_struct *vma) 322 void unlink_anon_vmas(struct vm_area_struct *vma)
323 { 323 {
324 struct anon_vma_chain *avc, *next; 324 struct anon_vma_chain *avc, *next;
325 struct anon_vma *root = NULL; 325 struct anon_vma *root = NULL;
326 326
327 /* 327 /*
328 * Unlink each anon_vma chained to the VMA. This list is ordered 328 * Unlink each anon_vma chained to the VMA. This list is ordered
329 * from newest to oldest, ensuring the root anon_vma gets freed last. 329 * from newest to oldest, ensuring the root anon_vma gets freed last.
330 */ 330 */
331 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { 331 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
332 struct anon_vma *anon_vma = avc->anon_vma; 332 struct anon_vma *anon_vma = avc->anon_vma;
333 333
334 root = lock_anon_vma_root(root, anon_vma); 334 root = lock_anon_vma_root(root, anon_vma);
335 anon_vma_interval_tree_remove(avc, &anon_vma->rb_root); 335 anon_vma_interval_tree_remove(avc, &anon_vma->rb_root);
336 336
337 /* 337 /*
338 * Leave empty anon_vmas on the list - we'll need 338 * Leave empty anon_vmas on the list - we'll need
339 * to free them outside the lock. 339 * to free them outside the lock.
340 */ 340 */
341 if (RB_EMPTY_ROOT(&anon_vma->rb_root)) 341 if (RB_EMPTY_ROOT(&anon_vma->rb_root))
342 continue; 342 continue;
343 343
344 list_del(&avc->same_vma); 344 list_del(&avc->same_vma);
345 anon_vma_chain_free(avc); 345 anon_vma_chain_free(avc);
346 } 346 }
347 unlock_anon_vma_root(root); 347 unlock_anon_vma_root(root);
348 348
349 /* 349 /*
350 * Iterate the list once more, it now only contains empty and unlinked 350 * Iterate the list once more, it now only contains empty and unlinked
351 * anon_vmas, destroy them. Could not do before due to __put_anon_vma() 351 * anon_vmas, destroy them. Could not do before due to __put_anon_vma()
352 * needing to write-acquire the anon_vma->root->rwsem. 352 * needing to write-acquire the anon_vma->root->rwsem.
353 */ 353 */
354 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { 354 list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) {
355 struct anon_vma *anon_vma = avc->anon_vma; 355 struct anon_vma *anon_vma = avc->anon_vma;
356 356
357 put_anon_vma(anon_vma); 357 put_anon_vma(anon_vma);
358 358
359 list_del(&avc->same_vma); 359 list_del(&avc->same_vma);
360 anon_vma_chain_free(avc); 360 anon_vma_chain_free(avc);
361 } 361 }
362 } 362 }
363 363
364 static void anon_vma_ctor(void *data) 364 static void anon_vma_ctor(void *data)
365 { 365 {
366 struct anon_vma *anon_vma = data; 366 struct anon_vma *anon_vma = data;
367 367
368 init_rwsem(&anon_vma->rwsem); 368 init_rwsem(&anon_vma->rwsem);
369 atomic_set(&anon_vma->refcount, 0); 369 atomic_set(&anon_vma->refcount, 0);
370 anon_vma->rb_root = RB_ROOT; 370 anon_vma->rb_root = RB_ROOT;
371 } 371 }
372 372
373 void __init anon_vma_init(void) 373 void __init anon_vma_init(void)
374 { 374 {
375 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), 375 anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
376 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); 376 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor);
377 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC); 377 anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC);
378 } 378 }
379 379
380 /* 380 /*
381 * Getting a lock on a stable anon_vma from a page off the LRU is tricky! 381 * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
382 * 382 *
383 * Since there is no serialization what so ever against page_remove_rmap() 383 * Since there is no serialization what so ever against page_remove_rmap()
384 * the best this function can do is return a locked anon_vma that might 384 * the best this function can do is return a locked anon_vma that might
385 * have been relevant to this page. 385 * have been relevant to this page.
386 * 386 *
387 * The page might have been remapped to a different anon_vma or the anon_vma 387 * The page might have been remapped to a different anon_vma or the anon_vma
388 * returned may already be freed (and even reused). 388 * returned may already be freed (and even reused).
389 * 389 *
390 * In case it was remapped to a different anon_vma, the new anon_vma will be a 390 * In case it was remapped to a different anon_vma, the new anon_vma will be a
391 * child of the old anon_vma, and the anon_vma lifetime rules will therefore 391 * child of the old anon_vma, and the anon_vma lifetime rules will therefore
392 * ensure that any anon_vma obtained from the page will still be valid for as 392 * ensure that any anon_vma obtained from the page will still be valid for as
393 * long as we observe page_mapped() [ hence all those page_mapped() tests ]. 393 * long as we observe page_mapped() [ hence all those page_mapped() tests ].
394 * 394 *
395 * All users of this function must be very careful when walking the anon_vma 395 * All users of this function must be very careful when walking the anon_vma
396 * chain and verify that the page in question is indeed mapped in it 396 * chain and verify that the page in question is indeed mapped in it
397 * [ something equivalent to page_mapped_in_vma() ]. 397 * [ something equivalent to page_mapped_in_vma() ].
398 * 398 *
399 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap() 399 * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
400 * that the anon_vma pointer from page->mapping is valid if there is a 400 * that the anon_vma pointer from page->mapping is valid if there is a
401 * mapcount, we can dereference the anon_vma after observing those. 401 * mapcount, we can dereference the anon_vma after observing those.
402 */ 402 */
403 struct anon_vma *page_get_anon_vma(struct page *page) 403 struct anon_vma *page_get_anon_vma(struct page *page)
404 { 404 {
405 struct anon_vma *anon_vma = NULL; 405 struct anon_vma *anon_vma = NULL;
406 unsigned long anon_mapping; 406 unsigned long anon_mapping;
407 407
408 rcu_read_lock(); 408 rcu_read_lock();
409 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); 409 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
410 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) 410 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
411 goto out; 411 goto out;
412 if (!page_mapped(page)) 412 if (!page_mapped(page))
413 goto out; 413 goto out;
414 414
415 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); 415 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
416 if (!atomic_inc_not_zero(&anon_vma->refcount)) { 416 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
417 anon_vma = NULL; 417 anon_vma = NULL;
418 goto out; 418 goto out;
419 } 419 }
420 420
421 /* 421 /*
422 * If this page is still mapped, then its anon_vma cannot have been 422 * If this page is still mapped, then its anon_vma cannot have been
423 * freed. But if it has been unmapped, we have no security against the 423 * freed. But if it has been unmapped, we have no security against the
424 * anon_vma structure being freed and reused (for another anon_vma: 424 * anon_vma structure being freed and reused (for another anon_vma:
425 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero() 425 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
426 * above cannot corrupt). 426 * above cannot corrupt).
427 */ 427 */
428 if (!page_mapped(page)) { 428 if (!page_mapped(page)) {
429 put_anon_vma(anon_vma); 429 put_anon_vma(anon_vma);
430 anon_vma = NULL; 430 anon_vma = NULL;
431 } 431 }
432 out: 432 out:
433 rcu_read_unlock(); 433 rcu_read_unlock();
434 434
435 return anon_vma; 435 return anon_vma;
436 } 436 }
437 437
438 /* 438 /*
439 * Similar to page_get_anon_vma() except it locks the anon_vma. 439 * Similar to page_get_anon_vma() except it locks the anon_vma.
440 * 440 *
441 * Its a little more complex as it tries to keep the fast path to a single 441 * Its a little more complex as it tries to keep the fast path to a single
442 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a 442 * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
443 * reference like with page_get_anon_vma() and then block on the mutex. 443 * reference like with page_get_anon_vma() and then block on the mutex.
444 */ 444 */
445 struct anon_vma *page_lock_anon_vma_read(struct page *page) 445 struct anon_vma *page_lock_anon_vma_read(struct page *page)
446 { 446 {
447 struct anon_vma *anon_vma = NULL; 447 struct anon_vma *anon_vma = NULL;
448 struct anon_vma *root_anon_vma; 448 struct anon_vma *root_anon_vma;
449 unsigned long anon_mapping; 449 unsigned long anon_mapping;
450 450
451 rcu_read_lock(); 451 rcu_read_lock();
452 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); 452 anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
453 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) 453 if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
454 goto out; 454 goto out;
455 if (!page_mapped(page)) 455 if (!page_mapped(page))
456 goto out; 456 goto out;
457 457
458 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); 458 anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
459 root_anon_vma = ACCESS_ONCE(anon_vma->root); 459 root_anon_vma = ACCESS_ONCE(anon_vma->root);
460 if (down_read_trylock(&root_anon_vma->rwsem)) { 460 if (down_read_trylock(&root_anon_vma->rwsem)) {
461 /* 461 /*
462 * If the page is still mapped, then this anon_vma is still 462 * If the page is still mapped, then this anon_vma is still
463 * its anon_vma, and holding the mutex ensures that it will 463 * its anon_vma, and holding the mutex ensures that it will
464 * not go away, see anon_vma_free(). 464 * not go away, see anon_vma_free().
465 */ 465 */
466 if (!page_mapped(page)) { 466 if (!page_mapped(page)) {
467 up_read(&root_anon_vma->rwsem); 467 up_read(&root_anon_vma->rwsem);
468 anon_vma = NULL; 468 anon_vma = NULL;
469 } 469 }
470 goto out; 470 goto out;
471 } 471 }
472 472
473 /* trylock failed, we got to sleep */ 473 /* trylock failed, we got to sleep */
474 if (!atomic_inc_not_zero(&anon_vma->refcount)) { 474 if (!atomic_inc_not_zero(&anon_vma->refcount)) {
475 anon_vma = NULL; 475 anon_vma = NULL;
476 goto out; 476 goto out;
477 } 477 }
478 478
479 if (!page_mapped(page)) { 479 if (!page_mapped(page)) {
480 put_anon_vma(anon_vma); 480 put_anon_vma(anon_vma);
481 anon_vma = NULL; 481 anon_vma = NULL;
482 goto out; 482 goto out;
483 } 483 }
484 484
485 /* we pinned the anon_vma, its safe to sleep */ 485 /* we pinned the anon_vma, its safe to sleep */
486 rcu_read_unlock(); 486 rcu_read_unlock();
487 anon_vma_lock_read(anon_vma); 487 anon_vma_lock_read(anon_vma);
488 488
489 if (atomic_dec_and_test(&anon_vma->refcount)) { 489 if (atomic_dec_and_test(&anon_vma->refcount)) {
490 /* 490 /*
491 * Oops, we held the last refcount, release the lock 491 * Oops, we held the last refcount, release the lock
492 * and bail -- can't simply use put_anon_vma() because 492 * and bail -- can't simply use put_anon_vma() because
493 * we'll deadlock on the anon_vma_lock_write() recursion. 493 * we'll deadlock on the anon_vma_lock_write() recursion.
494 */ 494 */
495 anon_vma_unlock_read(anon_vma); 495 anon_vma_unlock_read(anon_vma);
496 __put_anon_vma(anon_vma); 496 __put_anon_vma(anon_vma);
497 anon_vma = NULL; 497 anon_vma = NULL;
498 } 498 }
499 499
500 return anon_vma; 500 return anon_vma;
501 501
502 out: 502 out:
503 rcu_read_unlock(); 503 rcu_read_unlock();
504 return anon_vma; 504 return anon_vma;
505 } 505 }
506 506
507 void page_unlock_anon_vma_read(struct anon_vma *anon_vma) 507 void page_unlock_anon_vma_read(struct anon_vma *anon_vma)
508 { 508 {
509 anon_vma_unlock_read(anon_vma); 509 anon_vma_unlock_read(anon_vma);
510 } 510 }
511 511
512 /* 512 /*
513 * At what user virtual address is page expected in @vma? 513 * At what user virtual address is page expected in @vma?
514 */ 514 */
515 static inline unsigned long 515 static inline unsigned long
516 __vma_address(struct page *page, struct vm_area_struct *vma) 516 __vma_address(struct page *page, struct vm_area_struct *vma)
517 { 517 {
518 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); 518 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
519 519
520 if (unlikely(is_vm_hugetlb_page(vma))) 520 if (unlikely(is_vm_hugetlb_page(vma)))
521 pgoff = page->index << huge_page_order(page_hstate(page)); 521 pgoff = page->index << huge_page_order(page_hstate(page));
522 522
523 return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); 523 return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
524 } 524 }
525 525
526 inline unsigned long 526 inline unsigned long
527 vma_address(struct page *page, struct vm_area_struct *vma) 527 vma_address(struct page *page, struct vm_area_struct *vma)
528 { 528 {
529 unsigned long address = __vma_address(page, vma); 529 unsigned long address = __vma_address(page, vma);
530 530
531 /* page should be within @vma mapping range */ 531 /* page should be within @vma mapping range */
532 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); 532 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
533 533
534 return address; 534 return address;
535 } 535 }
536 536
537 /* 537 /*
538 * At what user virtual address is page expected in vma? 538 * At what user virtual address is page expected in vma?
539 * Caller should check the page is actually part of the vma. 539 * Caller should check the page is actually part of the vma.
540 */ 540 */
541 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) 541 unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
542 { 542 {
543 unsigned long address; 543 unsigned long address;
544 if (PageAnon(page)) { 544 if (PageAnon(page)) {
545 struct anon_vma *page__anon_vma = page_anon_vma(page); 545 struct anon_vma *page__anon_vma = page_anon_vma(page);
546 /* 546 /*
547 * Note: swapoff's unuse_vma() is more efficient with this 547 * Note: swapoff's unuse_vma() is more efficient with this
548 * check, and needs it to match anon_vma when KSM is active. 548 * check, and needs it to match anon_vma when KSM is active.
549 */ 549 */
550 if (!vma->anon_vma || !page__anon_vma || 550 if (!vma->anon_vma || !page__anon_vma ||
551 vma->anon_vma->root != page__anon_vma->root) 551 vma->anon_vma->root != page__anon_vma->root)
552 return -EFAULT; 552 return -EFAULT;
553 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { 553 } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
554 if (!vma->vm_file || 554 if (!vma->vm_file ||
555 vma->vm_file->f_mapping != page->mapping) 555 vma->vm_file->f_mapping != page->mapping)
556 return -EFAULT; 556 return -EFAULT;
557 } else 557 } else
558 return -EFAULT; 558 return -EFAULT;
559 address = __vma_address(page, vma); 559 address = __vma_address(page, vma);
560 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) 560 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
561 return -EFAULT; 561 return -EFAULT;
562 return address; 562 return address;
563 } 563 }
564 564
565 pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address) 565 pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address)
566 { 566 {
567 pgd_t *pgd; 567 pgd_t *pgd;
568 pud_t *pud; 568 pud_t *pud;
569 pmd_t *pmd = NULL; 569 pmd_t *pmd = NULL;
570 570
571 pgd = pgd_offset(mm, address); 571 pgd = pgd_offset(mm, address);
572 if (!pgd_present(*pgd)) 572 if (!pgd_present(*pgd))
573 goto out; 573 goto out;
574 574
575 pud = pud_offset(pgd, address); 575 pud = pud_offset(pgd, address);
576 if (!pud_present(*pud)) 576 if (!pud_present(*pud))
577 goto out; 577 goto out;
578 578
579 pmd = pmd_offset(pud, address); 579 pmd = pmd_offset(pud, address);
580 if (!pmd_present(*pmd)) 580 if (!pmd_present(*pmd))
581 pmd = NULL; 581 pmd = NULL;
582 out: 582 out:
583 return pmd; 583 return pmd;
584 } 584 }
585 585
586 /* 586 /*
587 * Check that @page is mapped at @address into @mm. 587 * Check that @page is mapped at @address into @mm.
588 * 588 *
589 * If @sync is false, page_check_address may perform a racy check to avoid 589 * If @sync is false, page_check_address may perform a racy check to avoid
590 * the page table lock when the pte is not present (helpful when reclaiming 590 * the page table lock when the pte is not present (helpful when reclaiming
591 * highly shared pages). 591 * highly shared pages).
592 * 592 *
593 * On success returns with pte mapped and locked. 593 * On success returns with pte mapped and locked.
594 */ 594 */
595 pte_t *__page_check_address(struct page *page, struct mm_struct *mm, 595 pte_t *__page_check_address(struct page *page, struct mm_struct *mm,
596 unsigned long address, spinlock_t **ptlp, int sync) 596 unsigned long address, spinlock_t **ptlp, int sync)
597 { 597 {
598 pmd_t *pmd; 598 pmd_t *pmd;
599 pte_t *pte; 599 pte_t *pte;
600 spinlock_t *ptl; 600 spinlock_t *ptl;
601 601
602 if (unlikely(PageHuge(page))) { 602 if (unlikely(PageHuge(page))) {
603 /* when pud is not present, pte will be NULL */ 603 /* when pud is not present, pte will be NULL */
604 pte = huge_pte_offset(mm, address); 604 pte = huge_pte_offset(mm, address);
605 if (!pte) 605 if (!pte)
606 return NULL; 606 return NULL;
607 607
608 ptl = huge_pte_lockptr(page_hstate(page), mm, pte); 608 ptl = huge_pte_lockptr(page_hstate(page), mm, pte);
609 goto check; 609 goto check;
610 } 610 }
611 611
612 pmd = mm_find_pmd(mm, address); 612 pmd = mm_find_pmd(mm, address);
613 if (!pmd) 613 if (!pmd)
614 return NULL; 614 return NULL;
615 615
616 if (pmd_trans_huge(*pmd)) 616 if (pmd_trans_huge(*pmd))
617 return NULL; 617 return NULL;
618 618
619 pte = pte_offset_map(pmd, address); 619 pte = pte_offset_map(pmd, address);
620 /* Make a quick check before getting the lock */ 620 /* Make a quick check before getting the lock */
621 if (!sync && !pte_present(*pte)) { 621 if (!sync && !pte_present(*pte)) {
622 pte_unmap(pte); 622 pte_unmap(pte);
623 return NULL; 623 return NULL;
624 } 624 }
625 625
626 ptl = pte_lockptr(mm, pmd); 626 ptl = pte_lockptr(mm, pmd);
627 check: 627 check:
628 spin_lock(ptl); 628 spin_lock(ptl);
629 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { 629 if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
630 *ptlp = ptl; 630 *ptlp = ptl;
631 return pte; 631 return pte;
632 } 632 }
633 pte_unmap_unlock(pte, ptl); 633 pte_unmap_unlock(pte, ptl);
634 return NULL; 634 return NULL;
635 } 635 }
636 636
637 /** 637 /**
638 * page_mapped_in_vma - check whether a page is really mapped in a VMA 638 * page_mapped_in_vma - check whether a page is really mapped in a VMA
639 * @page: the page to test 639 * @page: the page to test
640 * @vma: the VMA to test 640 * @vma: the VMA to test
641 * 641 *
642 * Returns 1 if the page is mapped into the page tables of the VMA, 0 642 * Returns 1 if the page is mapped into the page tables of the VMA, 0
643 * if the page is not mapped into the page tables of this VMA. Only 643 * if the page is not mapped into the page tables of this VMA. Only
644 * valid for normal file or anonymous VMAs. 644 * valid for normal file or anonymous VMAs.
645 */ 645 */
646 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) 646 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma)
647 { 647 {
648 unsigned long address; 648 unsigned long address;
649 pte_t *pte; 649 pte_t *pte;
650 spinlock_t *ptl; 650 spinlock_t *ptl;
651 651
652 address = __vma_address(page, vma); 652 address = __vma_address(page, vma);
653 if (unlikely(address < vma->vm_start || address >= vma->vm_end)) 653 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
654 return 0; 654 return 0;
655 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); 655 pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);
656 if (!pte) /* the page is not in this mm */ 656 if (!pte) /* the page is not in this mm */
657 return 0; 657 return 0;
658 pte_unmap_unlock(pte, ptl); 658 pte_unmap_unlock(pte, ptl);
659 659
660 return 1; 660 return 1;
661 } 661 }
662 662
663 struct page_referenced_arg { 663 struct page_referenced_arg {
664 int mapcount; 664 int mapcount;
665 int referenced; 665 int referenced;
666 unsigned long vm_flags; 666 unsigned long vm_flags;
667 struct mem_cgroup *memcg; 667 struct mem_cgroup *memcg;
668 }; 668 };
669 /* 669 /*
670 * arg: page_referenced_arg will be passed 670 * arg: page_referenced_arg will be passed
671 */ 671 */
672 int page_referenced_one(struct page *page, struct vm_area_struct *vma, 672 int page_referenced_one(struct page *page, struct vm_area_struct *vma,
673 unsigned long address, void *arg) 673 unsigned long address, void *arg)
674 { 674 {
675 struct mm_struct *mm = vma->vm_mm; 675 struct mm_struct *mm = vma->vm_mm;
676 spinlock_t *ptl; 676 spinlock_t *ptl;
677 int referenced = 0; 677 int referenced = 0;
678 struct page_referenced_arg *pra = arg; 678 struct page_referenced_arg *pra = arg;
679 679
680 if (unlikely(PageTransHuge(page))) { 680 if (unlikely(PageTransHuge(page))) {
681 pmd_t *pmd; 681 pmd_t *pmd;
682 682
683 /* 683 /*
684 * rmap might return false positives; we must filter 684 * rmap might return false positives; we must filter
685 * these out using page_check_address_pmd(). 685 * these out using page_check_address_pmd().
686 */ 686 */
687 pmd = page_check_address_pmd(page, mm, address, 687 pmd = page_check_address_pmd(page, mm, address,
688 PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl); 688 PAGE_CHECK_ADDRESS_PMD_FLAG, &ptl);
689 if (!pmd) 689 if (!pmd)
690 return SWAP_AGAIN; 690 return SWAP_AGAIN;
691 691
692 if (vma->vm_flags & VM_LOCKED) { 692 if (vma->vm_flags & VM_LOCKED) {
693 spin_unlock(ptl); 693 spin_unlock(ptl);
694 pra->vm_flags |= VM_LOCKED; 694 pra->vm_flags |= VM_LOCKED;
695 return SWAP_FAIL; /* To break the loop */ 695 return SWAP_FAIL; /* To break the loop */
696 } 696 }
697 697
698 /* go ahead even if the pmd is pmd_trans_splitting() */ 698 /* go ahead even if the pmd is pmd_trans_splitting() */
699 if (pmdp_clear_flush_young_notify(vma, address, pmd)) 699 if (pmdp_clear_flush_young_notify(vma, address, pmd))
700 referenced++; 700 referenced++;
701 spin_unlock(ptl); 701 spin_unlock(ptl);
702 } else { 702 } else {
703 pte_t *pte; 703 pte_t *pte;
704 704
705 /* 705 /*
706 * rmap might return false positives; we must filter 706 * rmap might return false positives; we must filter
707 * these out using page_check_address(). 707 * these out using page_check_address().
708 */ 708 */
709 pte = page_check_address(page, mm, address, &ptl, 0); 709 pte = page_check_address(page, mm, address, &ptl, 0);
710 if (!pte) 710 if (!pte)
711 return SWAP_AGAIN; 711 return SWAP_AGAIN;
712 712
713 if (vma->vm_flags & VM_LOCKED) { 713 if (vma->vm_flags & VM_LOCKED) {
714 pte_unmap_unlock(pte, ptl); 714 pte_unmap_unlock(pte, ptl);
715 pra->vm_flags |= VM_LOCKED; 715 pra->vm_flags |= VM_LOCKED;
716 return SWAP_FAIL; /* To break the loop */ 716 return SWAP_FAIL; /* To break the loop */
717 } 717 }
718 718
719 if (ptep_clear_flush_young_notify(vma, address, pte)) { 719 if (ptep_clear_flush_young_notify(vma, address, pte)) {
720 /* 720 /*
721 * Don't treat a reference through a sequentially read 721 * Don't treat a reference through a sequentially read
722 * mapping as such. If the page has been used in 722 * mapping as such. If the page has been used in
723 * another mapping, we will catch it; if this other 723 * another mapping, we will catch it; if this other
724 * mapping is already gone, the unmap path will have 724 * mapping is already gone, the unmap path will have
725 * set PG_referenced or activated the page. 725 * set PG_referenced or activated the page.
726 */ 726 */
727 if (likely(!(vma->vm_flags & VM_SEQ_READ))) 727 if (likely(!(vma->vm_flags & VM_SEQ_READ)))
728 referenced++; 728 referenced++;
729 } 729 }
730 pte_unmap_unlock(pte, ptl); 730 pte_unmap_unlock(pte, ptl);
731 } 731 }
732 732
733 if (referenced) { 733 if (referenced) {
734 pra->referenced++; 734 pra->referenced++;
735 pra->vm_flags |= vma->vm_flags; 735 pra->vm_flags |= vma->vm_flags;
736 } 736 }
737 737
738 pra->mapcount--; 738 pra->mapcount--;
739 if (!pra->mapcount) 739 if (!pra->mapcount)
740 return SWAP_SUCCESS; /* To break the loop */ 740 return SWAP_SUCCESS; /* To break the loop */
741 741
742 return SWAP_AGAIN; 742 return SWAP_AGAIN;
743 } 743 }
744 744
745 static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg) 745 static bool invalid_page_referenced_vma(struct vm_area_struct *vma, void *arg)
746 { 746 {
747 struct page_referenced_arg *pra = arg; 747 struct page_referenced_arg *pra = arg;
748 struct mem_cgroup *memcg = pra->memcg; 748 struct mem_cgroup *memcg = pra->memcg;
749 749
750 if (!mm_match_cgroup(vma->vm_mm, memcg)) 750 if (!mm_match_cgroup(vma->vm_mm, memcg))
751 return true; 751 return true;
752 752
753 return false; 753 return false;
754 } 754 }
755 755
756 /** 756 /**
757 * page_referenced - test if the page was referenced 757 * page_referenced - test if the page was referenced
758 * @page: the page to test 758 * @page: the page to test
759 * @is_locked: caller holds lock on the page 759 * @is_locked: caller holds lock on the page
760 * @memcg: target memory cgroup 760 * @memcg: target memory cgroup
761 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page 761 * @vm_flags: collect encountered vma->vm_flags who actually referenced the page
762 * 762 *
763 * Quick test_and_clear_referenced for all mappings to a page, 763 * Quick test_and_clear_referenced for all mappings to a page,
764 * returns the number of ptes which referenced the page. 764 * returns the number of ptes which referenced the page.
765 */ 765 */
766 int page_referenced(struct page *page, 766 int page_referenced(struct page *page,
767 int is_locked, 767 int is_locked,
768 struct mem_cgroup *memcg, 768 struct mem_cgroup *memcg,
769 unsigned long *vm_flags) 769 unsigned long *vm_flags)
770 { 770 {
771 int ret; 771 int ret;
772 int we_locked = 0; 772 int we_locked = 0;
773 struct page_referenced_arg pra = { 773 struct page_referenced_arg pra = {
774 .mapcount = page_mapcount(page), 774 .mapcount = page_mapcount(page),
775 .memcg = memcg, 775 .memcg = memcg,
776 }; 776 };
777 struct rmap_walk_control rwc = { 777 struct rmap_walk_control rwc = {
778 .rmap_one = page_referenced_one, 778 .rmap_one = page_referenced_one,
779 .arg = (void *)&pra, 779 .arg = (void *)&pra,
780 .anon_lock = page_lock_anon_vma_read, 780 .anon_lock = page_lock_anon_vma_read,
781 }; 781 };
782 782
783 *vm_flags = 0; 783 *vm_flags = 0;
784 if (!page_mapped(page)) 784 if (!page_mapped(page))
785 return 0; 785 return 0;
786 786
787 if (!page_rmapping(page)) 787 if (!page_rmapping(page))
788 return 0; 788 return 0;
789 789
790 if (!is_locked && (!PageAnon(page) || PageKsm(page))) { 790 if (!is_locked && (!PageAnon(page) || PageKsm(page))) {
791 we_locked = trylock_page(page); 791 we_locked = trylock_page(page);
792 if (!we_locked) 792 if (!we_locked)
793 return 1; 793 return 1;
794 } 794 }
795 795
796 /* 796 /*
797 * If we are reclaiming on behalf of a cgroup, skip 797 * If we are reclaiming on behalf of a cgroup, skip
798 * counting on behalf of references from different 798 * counting on behalf of references from different
799 * cgroups 799 * cgroups
800 */ 800 */
801 if (memcg) { 801 if (memcg) {
802 rwc.invalid_vma = invalid_page_referenced_vma; 802 rwc.invalid_vma = invalid_page_referenced_vma;
803 } 803 }
804 804
805 ret = rmap_walk(page, &rwc); 805 ret = rmap_walk(page, &rwc);
806 *vm_flags = pra.vm_flags; 806 *vm_flags = pra.vm_flags;
807 807
808 if (we_locked) 808 if (we_locked)
809 unlock_page(page); 809 unlock_page(page);
810 810
811 return pra.referenced; 811 return pra.referenced;
812 } 812 }
813 813
814 static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, 814 static int page_mkclean_one(struct page *page, struct vm_area_struct *vma,
815 unsigned long address, void *arg) 815 unsigned long address, void *arg)
816 { 816 {
817 struct mm_struct *mm = vma->vm_mm; 817 struct mm_struct *mm = vma->vm_mm;
818 pte_t *pte; 818 pte_t *pte;
819 spinlock_t *ptl; 819 spinlock_t *ptl;
820 int ret = 0; 820 int ret = 0;
821 int *cleaned = arg; 821 int *cleaned = arg;
822 822
823 pte = page_check_address(page, mm, address, &ptl, 1); 823 pte = page_check_address(page, mm, address, &ptl, 1);
824 if (!pte) 824 if (!pte)
825 goto out; 825 goto out;
826 826
827 if (pte_dirty(*pte) || pte_write(*pte)) { 827 if (pte_dirty(*pte) || pte_write(*pte)) {
828 pte_t entry; 828 pte_t entry;
829 829
830 flush_cache_page(vma, address, pte_pfn(*pte)); 830 flush_cache_page(vma, address, pte_pfn(*pte));
831 entry = ptep_clear_flush(vma, address, pte); 831 entry = ptep_clear_flush(vma, address, pte);
832 entry = pte_wrprotect(entry); 832 entry = pte_wrprotect(entry);
833 entry = pte_mkclean(entry); 833 entry = pte_mkclean(entry);
834 set_pte_at(mm, address, pte, entry); 834 set_pte_at(mm, address, pte, entry);
835 ret = 1; 835 ret = 1;
836 } 836 }
837 837
838 pte_unmap_unlock(pte, ptl); 838 pte_unmap_unlock(pte, ptl);
839 839
840 if (ret) { 840 if (ret) {
841 mmu_notifier_invalidate_page(mm, address); 841 mmu_notifier_invalidate_page(mm, address);
842 (*cleaned)++; 842 (*cleaned)++;
843 } 843 }
844 out: 844 out:
845 return SWAP_AGAIN; 845 return SWAP_AGAIN;
846 } 846 }
847 847
848 static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg) 848 static bool invalid_mkclean_vma(struct vm_area_struct *vma, void *arg)
849 { 849 {
850 if (vma->vm_flags & VM_SHARED) 850 if (vma->vm_flags & VM_SHARED)
851 return false; 851 return false;
852 852
853 return true; 853 return true;
854 } 854 }
855 855
856 int page_mkclean(struct page *page) 856 int page_mkclean(struct page *page)
857 { 857 {
858 int cleaned = 0; 858 int cleaned = 0;
859 struct address_space *mapping; 859 struct address_space *mapping;
860 struct rmap_walk_control rwc = { 860 struct rmap_walk_control rwc = {
861 .arg = (void *)&cleaned, 861 .arg = (void *)&cleaned,
862 .rmap_one = page_mkclean_one, 862 .rmap_one = page_mkclean_one,
863 .invalid_vma = invalid_mkclean_vma, 863 .invalid_vma = invalid_mkclean_vma,
864 }; 864 };
865 865
866 BUG_ON(!PageLocked(page)); 866 BUG_ON(!PageLocked(page));
867 867
868 if (!page_mapped(page)) 868 if (!page_mapped(page))
869 return 0; 869 return 0;
870 870
871 mapping = page_mapping(page); 871 mapping = page_mapping(page);
872 if (!mapping) 872 if (!mapping)
873 return 0; 873 return 0;
874 874
875 rmap_walk(page, &rwc); 875 rmap_walk(page, &rwc);
876 876
877 return cleaned; 877 return cleaned;
878 } 878 }
879 EXPORT_SYMBOL_GPL(page_mkclean); 879 EXPORT_SYMBOL_GPL(page_mkclean);
880 880
881 /** 881 /**
882 * page_move_anon_rmap - move a page to our anon_vma 882 * page_move_anon_rmap - move a page to our anon_vma
883 * @page: the page to move to our anon_vma 883 * @page: the page to move to our anon_vma
884 * @vma: the vma the page belongs to 884 * @vma: the vma the page belongs to
885 * @address: the user virtual address mapped 885 * @address: the user virtual address mapped
886 * 886 *
887 * When a page belongs exclusively to one process after a COW event, 887 * When a page belongs exclusively to one process after a COW event,
888 * that page can be moved into the anon_vma that belongs to just that 888 * that page can be moved into the anon_vma that belongs to just that
889 * process, so the rmap code will not search the parent or sibling 889 * process, so the rmap code will not search the parent or sibling
890 * processes. 890 * processes.
891 */ 891 */
892 void page_move_anon_rmap(struct page *page, 892 void page_move_anon_rmap(struct page *page,
893 struct vm_area_struct *vma, unsigned long address) 893 struct vm_area_struct *vma, unsigned long address)
894 { 894 {
895 struct anon_vma *anon_vma = vma->anon_vma; 895 struct anon_vma *anon_vma = vma->anon_vma;
896 896
897 VM_BUG_ON_PAGE(!PageLocked(page), page); 897 VM_BUG_ON_PAGE(!PageLocked(page), page);
898 VM_BUG_ON(!anon_vma); 898 VM_BUG_ON(!anon_vma);
899 VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page); 899 VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
900 900
901 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; 901 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
902 page->mapping = (struct address_space *) anon_vma; 902 page->mapping = (struct address_space *) anon_vma;
903 } 903 }
904 904
905 /** 905 /**
906 * __page_set_anon_rmap - set up new anonymous rmap 906 * __page_set_anon_rmap - set up new anonymous rmap
907 * @page: Page to add to rmap 907 * @page: Page to add to rmap
908 * @vma: VM area to add page to. 908 * @vma: VM area to add page to.
909 * @address: User virtual address of the mapping 909 * @address: User virtual address of the mapping
910 * @exclusive: the page is exclusively owned by the current process 910 * @exclusive: the page is exclusively owned by the current process
911 */ 911 */
912 static void __page_set_anon_rmap(struct page *page, 912 static void __page_set_anon_rmap(struct page *page,
913 struct vm_area_struct *vma, unsigned long address, int exclusive) 913 struct vm_area_struct *vma, unsigned long address, int exclusive)
914 { 914 {
915 struct anon_vma *anon_vma = vma->anon_vma; 915 struct anon_vma *anon_vma = vma->anon_vma;
916 916
917 BUG_ON(!anon_vma); 917 BUG_ON(!anon_vma);
918 918
919 if (PageAnon(page)) 919 if (PageAnon(page))
920 return; 920 return;
921 921
922 /* 922 /*
923 * If the page isn't exclusively mapped into this vma, 923 * If the page isn't exclusively mapped into this vma,
924 * we must use the _oldest_ possible anon_vma for the 924 * we must use the _oldest_ possible anon_vma for the
925 * page mapping! 925 * page mapping!
926 */ 926 */
927 if (!exclusive) 927 if (!exclusive)
928 anon_vma = anon_vma->root; 928 anon_vma = anon_vma->root;
929 929
930 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; 930 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
931 page->mapping = (struct address_space *) anon_vma; 931 page->mapping = (struct address_space *) anon_vma;
932 page->index = linear_page_index(vma, address); 932 page->index = linear_page_index(vma, address);
933 } 933 }
934 934
935 /** 935 /**
936 * __page_check_anon_rmap - sanity check anonymous rmap addition 936 * __page_check_anon_rmap - sanity check anonymous rmap addition
937 * @page: the page to add the mapping to 937 * @page: the page to add the mapping to
938 * @vma: the vm area in which the mapping is added 938 * @vma: the vm area in which the mapping is added
939 * @address: the user virtual address mapped 939 * @address: the user virtual address mapped
940 */ 940 */
941 static void __page_check_anon_rmap(struct page *page, 941 static void __page_check_anon_rmap(struct page *page,
942 struct vm_area_struct *vma, unsigned long address) 942 struct vm_area_struct *vma, unsigned long address)
943 { 943 {
944 #ifdef CONFIG_DEBUG_VM 944 #ifdef CONFIG_DEBUG_VM
945 /* 945 /*
946 * The page's anon-rmap details (mapping and index) are guaranteed to 946 * The page's anon-rmap details (mapping and index) are guaranteed to
947 * be set up correctly at this point. 947 * be set up correctly at this point.
948 * 948 *
949 * We have exclusion against page_add_anon_rmap because the caller 949 * We have exclusion against page_add_anon_rmap because the caller
950 * always holds the page locked, except if called from page_dup_rmap, 950 * always holds the page locked, except if called from page_dup_rmap,
951 * in which case the page is already known to be setup. 951 * in which case the page is already known to be setup.
952 * 952 *
953 * We have exclusion against page_add_new_anon_rmap because those pages 953 * We have exclusion against page_add_new_anon_rmap because those pages
954 * are initially only visible via the pagetables, and the pte is locked 954 * are initially only visible via the pagetables, and the pte is locked
955 * over the call to page_add_new_anon_rmap. 955 * over the call to page_add_new_anon_rmap.
956 */ 956 */
957 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); 957 BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root);
958 BUG_ON(page->index != linear_page_index(vma, address)); 958 BUG_ON(page->index != linear_page_index(vma, address));
959 #endif 959 #endif
960 } 960 }
961 961
962 /** 962 /**
963 * page_add_anon_rmap - add pte mapping to an anonymous page 963 * page_add_anon_rmap - add pte mapping to an anonymous page
964 * @page: the page to add the mapping to 964 * @page: the page to add the mapping to
965 * @vma: the vm area in which the mapping is added 965 * @vma: the vm area in which the mapping is added
966 * @address: the user virtual address mapped 966 * @address: the user virtual address mapped
967 * 967 *
968 * The caller needs to hold the pte lock, and the page must be locked in 968 * The caller needs to hold the pte lock, and the page must be locked in
969 * the anon_vma case: to serialize mapping,index checking after setting, 969 * the anon_vma case: to serialize mapping,index checking after setting,
970 * and to ensure that PageAnon is not being upgraded racily to PageKsm 970 * and to ensure that PageAnon is not being upgraded racily to PageKsm
971 * (but PageKsm is never downgraded to PageAnon). 971 * (but PageKsm is never downgraded to PageAnon).
972 */ 972 */
973 void page_add_anon_rmap(struct page *page, 973 void page_add_anon_rmap(struct page *page,
974 struct vm_area_struct *vma, unsigned long address) 974 struct vm_area_struct *vma, unsigned long address)
975 { 975 {
976 do_page_add_anon_rmap(page, vma, address, 0); 976 do_page_add_anon_rmap(page, vma, address, 0);
977 } 977 }
978 978
979 /* 979 /*
980 * Special version of the above for do_swap_page, which often runs 980 * Special version of the above for do_swap_page, which often runs
981 * into pages that are exclusively owned by the current process. 981 * into pages that are exclusively owned by the current process.
982 * Everybody else should continue to use page_add_anon_rmap above. 982 * Everybody else should continue to use page_add_anon_rmap above.
983 */ 983 */
984 void do_page_add_anon_rmap(struct page *page, 984 void do_page_add_anon_rmap(struct page *page,
985 struct vm_area_struct *vma, unsigned long address, int exclusive) 985 struct vm_area_struct *vma, unsigned long address, int exclusive)
986 { 986 {
987 int first = atomic_inc_and_test(&page->_mapcount); 987 int first = atomic_inc_and_test(&page->_mapcount);
988 if (first) { 988 if (first) {
989 if (PageTransHuge(page)) 989 if (PageTransHuge(page))
990 __inc_zone_page_state(page, 990 __inc_zone_page_state(page,
991 NR_ANON_TRANSPARENT_HUGEPAGES); 991 NR_ANON_TRANSPARENT_HUGEPAGES);
992 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, 992 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
993 hpage_nr_pages(page)); 993 hpage_nr_pages(page));
994 } 994 }
995 if (unlikely(PageKsm(page))) 995 if (unlikely(PageKsm(page)))
996 return; 996 return;
997 997
998 VM_BUG_ON_PAGE(!PageLocked(page), page); 998 VM_BUG_ON_PAGE(!PageLocked(page), page);
999 /* address might be in next vma when migration races vma_adjust */ 999 /* address might be in next vma when migration races vma_adjust */
1000 if (first) 1000 if (first)
1001 __page_set_anon_rmap(page, vma, address, exclusive); 1001 __page_set_anon_rmap(page, vma, address, exclusive);
1002 else 1002 else
1003 __page_check_anon_rmap(page, vma, address); 1003 __page_check_anon_rmap(page, vma, address);
1004 } 1004 }
1005 1005
1006 /** 1006 /**
1007 * page_add_new_anon_rmap - add pte mapping to a new anonymous page 1007 * page_add_new_anon_rmap - add pte mapping to a new anonymous page
1008 * @page: the page to add the mapping to 1008 * @page: the page to add the mapping to
1009 * @vma: the vm area in which the mapping is added 1009 * @vma: the vm area in which the mapping is added
1010 * @address: the user virtual address mapped 1010 * @address: the user virtual address mapped
1011 * 1011 *
1012 * Same as page_add_anon_rmap but must only be called on *new* pages. 1012 * Same as page_add_anon_rmap but must only be called on *new* pages.
1013 * This means the inc-and-test can be bypassed. 1013 * This means the inc-and-test can be bypassed.
1014 * Page does not have to be locked. 1014 * Page does not have to be locked.
1015 */ 1015 */
1016 void page_add_new_anon_rmap(struct page *page, 1016 void page_add_new_anon_rmap(struct page *page,
1017 struct vm_area_struct *vma, unsigned long address) 1017 struct vm_area_struct *vma, unsigned long address)
1018 { 1018 {
1019 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); 1019 VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1020 SetPageSwapBacked(page); 1020 SetPageSwapBacked(page);
1021 atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ 1021 atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
1022 if (PageTransHuge(page)) 1022 if (PageTransHuge(page))
1023 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); 1023 __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES);
1024 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, 1024 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
1025 hpage_nr_pages(page)); 1025 hpage_nr_pages(page));
1026 __page_set_anon_rmap(page, vma, address, 1); 1026 __page_set_anon_rmap(page, vma, address, 1);
1027 if (!mlocked_vma_newpage(vma, page)) { 1027 if (!mlocked_vma_newpage(vma, page)) {
1028 SetPageActive(page); 1028 SetPageActive(page);
1029 lru_cache_add(page); 1029 lru_cache_add(page);
1030 } else 1030 } else
1031 add_page_to_unevictable_list(page); 1031 add_page_to_unevictable_list(page);
1032 } 1032 }
1033 1033
1034 /** 1034 /**
1035 * page_add_file_rmap - add pte mapping to a file page 1035 * page_add_file_rmap - add pte mapping to a file page
1036 * @page: the page to add the mapping to 1036 * @page: the page to add the mapping to
1037 * 1037 *
1038 * The caller needs to hold the pte lock. 1038 * The caller needs to hold the pte lock.
1039 */ 1039 */
1040 void page_add_file_rmap(struct page *page) 1040 void page_add_file_rmap(struct page *page)
1041 { 1041 {
1042 bool locked; 1042 bool locked;
1043 unsigned long flags; 1043 unsigned long flags;
1044 1044
1045 mem_cgroup_begin_update_page_stat(page, &locked, &flags); 1045 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
1046 if (atomic_inc_and_test(&page->_mapcount)) { 1046 if (atomic_inc_and_test(&page->_mapcount)) {
1047 __inc_zone_page_state(page, NR_FILE_MAPPED); 1047 __inc_zone_page_state(page, NR_FILE_MAPPED);
1048 mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED); 1048 mem_cgroup_inc_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
1049 } 1049 }
1050 mem_cgroup_end_update_page_stat(page, &locked, &flags); 1050 mem_cgroup_end_update_page_stat(page, &locked, &flags);
1051 } 1051 }
1052 1052
1053 /** 1053 /**
1054 * page_remove_rmap - take down pte mapping from a page 1054 * page_remove_rmap - take down pte mapping from a page
1055 * @page: page to remove mapping from 1055 * @page: page to remove mapping from
1056 * 1056 *
1057 * The caller needs to hold the pte lock. 1057 * The caller needs to hold the pte lock.
1058 */ 1058 */
1059 void page_remove_rmap(struct page *page) 1059 void page_remove_rmap(struct page *page)
1060 { 1060 {
1061 bool anon = PageAnon(page); 1061 bool anon = PageAnon(page);
1062 bool locked; 1062 bool locked;
1063 unsigned long flags; 1063 unsigned long flags;
1064 1064
1065 /* 1065 /*
1066 * The anon case has no mem_cgroup page_stat to update; but may 1066 * The anon case has no mem_cgroup page_stat to update; but may
1067 * uncharge_page() below, where the lock ordering can deadlock if 1067 * uncharge_page() below, where the lock ordering can deadlock if
1068 * we hold the lock against page_stat move: so avoid it on anon. 1068 * we hold the lock against page_stat move: so avoid it on anon.
1069 */ 1069 */
1070 if (!anon) 1070 if (!anon)
1071 mem_cgroup_begin_update_page_stat(page, &locked, &flags); 1071 mem_cgroup_begin_update_page_stat(page, &locked, &flags);
1072 1072
1073 /* page still mapped by someone else? */ 1073 /* page still mapped by someone else? */
1074 if (!atomic_add_negative(-1, &page->_mapcount)) 1074 if (!atomic_add_negative(-1, &page->_mapcount))
1075 goto out; 1075 goto out;
1076 1076
1077 /* 1077 /*
1078 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED 1078 * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED
1079 * and not charged by memcg for now. 1079 * and not charged by memcg for now.
1080 */ 1080 */
1081 if (unlikely(PageHuge(page))) 1081 if (unlikely(PageHuge(page)))
1082 goto out; 1082 goto out;
1083 if (anon) { 1083 if (anon) {
1084 mem_cgroup_uncharge_page(page); 1084 mem_cgroup_uncharge_page(page);
1085 if (PageTransHuge(page)) 1085 if (PageTransHuge(page))
1086 __dec_zone_page_state(page, 1086 __dec_zone_page_state(page,
1087 NR_ANON_TRANSPARENT_HUGEPAGES); 1087 NR_ANON_TRANSPARENT_HUGEPAGES);
1088 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES, 1088 __mod_zone_page_state(page_zone(page), NR_ANON_PAGES,
1089 -hpage_nr_pages(page)); 1089 -hpage_nr_pages(page));
1090 } else { 1090 } else {
1091 __dec_zone_page_state(page, NR_FILE_MAPPED); 1091 __dec_zone_page_state(page, NR_FILE_MAPPED);
1092 mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED); 1092 mem_cgroup_dec_page_stat(page, MEM_CGROUP_STAT_FILE_MAPPED);
1093 mem_cgroup_end_update_page_stat(page, &locked, &flags); 1093 mem_cgroup_end_update_page_stat(page, &locked, &flags);
1094 } 1094 }
1095 if (unlikely(PageMlocked(page))) 1095 if (unlikely(PageMlocked(page)))
1096 clear_page_mlock(page); 1096 clear_page_mlock(page);
1097 /* 1097 /*
1098 * It would be tidy to reset the PageAnon mapping here, 1098 * It would be tidy to reset the PageAnon mapping here,
1099 * but that might overwrite a racing page_add_anon_rmap 1099 * but that might overwrite a racing page_add_anon_rmap
1100 * which increments mapcount after us but sets mapping 1100 * which increments mapcount after us but sets mapping
1101 * before us: so leave the reset to free_hot_cold_page, 1101 * before us: so leave the reset to free_hot_cold_page,
1102 * and remember that it's only reliable while mapped. 1102 * and remember that it's only reliable while mapped.
1103 * Leaving it set also helps swapoff to reinstate ptes 1103 * Leaving it set also helps swapoff to reinstate ptes
1104 * faster for those pages still in swapcache. 1104 * faster for those pages still in swapcache.
1105 */ 1105 */
1106 return; 1106 return;
1107 out: 1107 out:
1108 if (!anon) 1108 if (!anon)
1109 mem_cgroup_end_update_page_stat(page, &locked, &flags); 1109 mem_cgroup_end_update_page_stat(page, &locked, &flags);
1110 } 1110 }
1111 1111
1112 /* 1112 /*
1113 * @arg: enum ttu_flags will be passed to this argument 1113 * @arg: enum ttu_flags will be passed to this argument
1114 */ 1114 */
1115 int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, 1115 int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
1116 unsigned long address, void *arg) 1116 unsigned long address, void *arg)
1117 { 1117 {
1118 struct mm_struct *mm = vma->vm_mm; 1118 struct mm_struct *mm = vma->vm_mm;
1119 pte_t *pte; 1119 pte_t *pte;
1120 pte_t pteval; 1120 pte_t pteval;
1121 spinlock_t *ptl; 1121 spinlock_t *ptl;
1122 int ret = SWAP_AGAIN; 1122 int ret = SWAP_AGAIN;
1123 enum ttu_flags flags = (enum ttu_flags)arg; 1123 enum ttu_flags flags = (enum ttu_flags)arg;
1124 1124
1125 pte = page_check_address(page, mm, address, &ptl, 0); 1125 pte = page_check_address(page, mm, address, &ptl, 0);
1126 if (!pte) 1126 if (!pte)
1127 goto out; 1127 goto out;
1128 1128
1129 /* 1129 /*
1130 * If the page is mlock()d, we cannot swap it out. 1130 * If the page is mlock()d, we cannot swap it out.
1131 * If it's recently referenced (perhaps page_referenced 1131 * If it's recently referenced (perhaps page_referenced
1132 * skipped over this mm) then we should reactivate it. 1132 * skipped over this mm) then we should reactivate it.
1133 */ 1133 */
1134 if (!(flags & TTU_IGNORE_MLOCK)) { 1134 if (!(flags & TTU_IGNORE_MLOCK)) {
1135 if (vma->vm_flags & VM_LOCKED) 1135 if (vma->vm_flags & VM_LOCKED)
1136 goto out_mlock; 1136 goto out_mlock;
1137 1137
1138 if (TTU_ACTION(flags) == TTU_MUNLOCK) 1138 if (TTU_ACTION(flags) == TTU_MUNLOCK)
1139 goto out_unmap; 1139 goto out_unmap;
1140 } 1140 }
1141 if (!(flags & TTU_IGNORE_ACCESS)) { 1141 if (!(flags & TTU_IGNORE_ACCESS)) {
1142 if (ptep_clear_flush_young_notify(vma, address, pte)) { 1142 if (ptep_clear_flush_young_notify(vma, address, pte)) {
1143 ret = SWAP_FAIL; 1143 ret = SWAP_FAIL;
1144 goto out_unmap; 1144 goto out_unmap;
1145 } 1145 }
1146 } 1146 }
1147 1147
1148 /* Nuke the page table entry. */ 1148 /* Nuke the page table entry. */
1149 flush_cache_page(vma, address, page_to_pfn(page)); 1149 flush_cache_page(vma, address, page_to_pfn(page));
1150 pteval = ptep_clear_flush(vma, address, pte); 1150 pteval = ptep_clear_flush(vma, address, pte);
1151 1151
1152 /* Move the dirty bit to the physical page now the pte is gone. */ 1152 /* Move the dirty bit to the physical page now the pte is gone. */
1153 if (pte_dirty(pteval)) 1153 if (pte_dirty(pteval))
1154 set_page_dirty(page); 1154 set_page_dirty(page);
1155 1155
1156 /* Update high watermark before we lower rss */ 1156 /* Update high watermark before we lower rss */
1157 update_hiwater_rss(mm); 1157 update_hiwater_rss(mm);
1158 1158
1159 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { 1159 if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
1160 if (!PageHuge(page)) { 1160 if (!PageHuge(page)) {
1161 if (PageAnon(page)) 1161 if (PageAnon(page))
1162 dec_mm_counter(mm, MM_ANONPAGES); 1162 dec_mm_counter(mm, MM_ANONPAGES);
1163 else 1163 else
1164 dec_mm_counter(mm, MM_FILEPAGES); 1164 dec_mm_counter(mm, MM_FILEPAGES);
1165 } 1165 }
1166 set_pte_at(mm, address, pte, 1166 set_pte_at(mm, address, pte,
1167 swp_entry_to_pte(make_hwpoison_entry(page))); 1167 swp_entry_to_pte(make_hwpoison_entry(page)));
1168 } else if (pte_unused(pteval)) { 1168 } else if (pte_unused(pteval)) {
1169 /* 1169 /*
1170 * The guest indicated that the page content is of no 1170 * The guest indicated that the page content is of no
1171 * interest anymore. Simply discard the pte, vmscan 1171 * interest anymore. Simply discard the pte, vmscan
1172 * will take care of the rest. 1172 * will take care of the rest.
1173 */ 1173 */
1174 if (PageAnon(page)) 1174 if (PageAnon(page))
1175 dec_mm_counter(mm, MM_ANONPAGES); 1175 dec_mm_counter(mm, MM_ANONPAGES);
1176 else 1176 else
1177 dec_mm_counter(mm, MM_FILEPAGES); 1177 dec_mm_counter(mm, MM_FILEPAGES);
1178 } else if (PageAnon(page)) { 1178 } else if (PageAnon(page)) {
1179 swp_entry_t entry = { .val = page_private(page) }; 1179 swp_entry_t entry = { .val = page_private(page) };
1180 pte_t swp_pte; 1180 pte_t swp_pte;
1181 1181
1182 if (PageSwapCache(page)) { 1182 if (PageSwapCache(page)) {
1183 /* 1183 /*
1184 * Store the swap location in the pte. 1184 * Store the swap location in the pte.
1185 * See handle_pte_fault() ... 1185 * See handle_pte_fault() ...
1186 */ 1186 */
1187 if (swap_duplicate(entry) < 0) { 1187 if (swap_duplicate(entry) < 0) {
1188 set_pte_at(mm, address, pte, pteval); 1188 set_pte_at(mm, address, pte, pteval);
1189 ret = SWAP_FAIL; 1189 ret = SWAP_FAIL;
1190 goto out_unmap; 1190 goto out_unmap;
1191 } 1191 }
1192 if (list_empty(&mm->mmlist)) { 1192 if (list_empty(&mm->mmlist)) {
1193 spin_lock(&mmlist_lock); 1193 spin_lock(&mmlist_lock);
1194 if (list_empty(&mm->mmlist)) 1194 if (list_empty(&mm->mmlist))
1195 list_add(&mm->mmlist, &init_mm.mmlist); 1195 list_add(&mm->mmlist, &init_mm.mmlist);
1196 spin_unlock(&mmlist_lock); 1196 spin_unlock(&mmlist_lock);
1197 } 1197 }
1198 dec_mm_counter(mm, MM_ANONPAGES); 1198 dec_mm_counter(mm, MM_ANONPAGES);
1199 inc_mm_counter(mm, MM_SWAPENTS); 1199 inc_mm_counter(mm, MM_SWAPENTS);
1200 } else if (IS_ENABLED(CONFIG_MIGRATION)) { 1200 } else if (IS_ENABLED(CONFIG_MIGRATION)) {
1201 /* 1201 /*
1202 * Store the pfn of the page in a special migration 1202 * Store the pfn of the page in a special migration
1203 * pte. do_swap_page() will wait until the migration 1203 * pte. do_swap_page() will wait until the migration
1204 * pte is removed and then restart fault handling. 1204 * pte is removed and then restart fault handling.
1205 */ 1205 */
1206 BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION); 1206 BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION);
1207 entry = make_migration_entry(page, pte_write(pteval)); 1207 entry = make_migration_entry(page, pte_write(pteval));
1208 } 1208 }
1209 swp_pte = swp_entry_to_pte(entry); 1209 swp_pte = swp_entry_to_pte(entry);
1210 if (pte_soft_dirty(pteval)) 1210 if (pte_soft_dirty(pteval))
1211 swp_pte = pte_swp_mksoft_dirty(swp_pte); 1211 swp_pte = pte_swp_mksoft_dirty(swp_pte);
1212 set_pte_at(mm, address, pte, swp_pte); 1212 set_pte_at(mm, address, pte, swp_pte);
1213 BUG_ON(pte_file(*pte)); 1213 BUG_ON(pte_file(*pte));
1214 } else if (IS_ENABLED(CONFIG_MIGRATION) && 1214 } else if (IS_ENABLED(CONFIG_MIGRATION) &&
1215 (TTU_ACTION(flags) == TTU_MIGRATION)) { 1215 (TTU_ACTION(flags) == TTU_MIGRATION)) {
1216 /* Establish migration entry for a file page */ 1216 /* Establish migration entry for a file page */
1217 swp_entry_t entry; 1217 swp_entry_t entry;
1218 entry = make_migration_entry(page, pte_write(pteval)); 1218 entry = make_migration_entry(page, pte_write(pteval));
1219 set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); 1219 set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
1220 } else 1220 } else
1221 dec_mm_counter(mm, MM_FILEPAGES); 1221 dec_mm_counter(mm, MM_FILEPAGES);
1222 1222
1223 page_remove_rmap(page); 1223 page_remove_rmap(page);
1224 page_cache_release(page); 1224 page_cache_release(page);
1225 1225
1226 out_unmap: 1226 out_unmap:
1227 pte_unmap_unlock(pte, ptl); 1227 pte_unmap_unlock(pte, ptl);
1228 if (ret != SWAP_FAIL) 1228 if (ret != SWAP_FAIL)
1229 mmu_notifier_invalidate_page(mm, address); 1229 mmu_notifier_invalidate_page(mm, address);
1230 out: 1230 out:
1231 return ret; 1231 return ret;
1232 1232
1233 out_mlock: 1233 out_mlock:
1234 pte_unmap_unlock(pte, ptl); 1234 pte_unmap_unlock(pte, ptl);
1235 1235
1236 1236
1237 /* 1237 /*
1238 * We need mmap_sem locking, Otherwise VM_LOCKED check makes 1238 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
1239 * unstable result and race. Plus, We can't wait here because 1239 * unstable result and race. Plus, We can't wait here because
1240 * we now hold anon_vma->rwsem or mapping->i_mmap_mutex. 1240 * we now hold anon_vma->rwsem or mapping->i_mmap_mutex.
1241 * if trylock failed, the page remain in evictable lru and later 1241 * if trylock failed, the page remain in evictable lru and later
1242 * vmscan could retry to move the page to unevictable lru if the 1242 * vmscan could retry to move the page to unevictable lru if the
1243 * page is actually mlocked. 1243 * page is actually mlocked.
1244 */ 1244 */
1245 if (down_read_trylock(&vma->vm_mm->mmap_sem)) { 1245 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
1246 if (vma->vm_flags & VM_LOCKED) { 1246 if (vma->vm_flags & VM_LOCKED) {
1247 mlock_vma_page(page); 1247 mlock_vma_page(page);
1248 ret = SWAP_MLOCK; 1248 ret = SWAP_MLOCK;
1249 } 1249 }
1250 up_read(&vma->vm_mm->mmap_sem); 1250 up_read(&vma->vm_mm->mmap_sem);
1251 } 1251 }
1252 return ret; 1252 return ret;
1253 } 1253 }
1254 1254
1255 /* 1255 /*
1256 * objrmap doesn't work for nonlinear VMAs because the assumption that 1256 * objrmap doesn't work for nonlinear VMAs because the assumption that
1257 * offset-into-file correlates with offset-into-virtual-addresses does not hold. 1257 * offset-into-file correlates with offset-into-virtual-addresses does not hold.
1258 * Consequently, given a particular page and its ->index, we cannot locate the 1258 * Consequently, given a particular page and its ->index, we cannot locate the
1259 * ptes which are mapping that page without an exhaustive linear search. 1259 * ptes which are mapping that page without an exhaustive linear search.
1260 * 1260 *
1261 * So what this code does is a mini "virtual scan" of each nonlinear VMA which 1261 * So what this code does is a mini "virtual scan" of each nonlinear VMA which
1262 * maps the file to which the target page belongs. The ->vm_private_data field 1262 * maps the file to which the target page belongs. The ->vm_private_data field
1263 * holds the current cursor into that scan. Successive searches will circulate 1263 * holds the current cursor into that scan. Successive searches will circulate
1264 * around the vma's virtual address space. 1264 * around the vma's virtual address space.
1265 * 1265 *
1266 * So as more replacement pressure is applied to the pages in a nonlinear VMA, 1266 * So as more replacement pressure is applied to the pages in a nonlinear VMA,
1267 * more scanning pressure is placed against them as well. Eventually pages 1267 * more scanning pressure is placed against them as well. Eventually pages
1268 * will become fully unmapped and are eligible for eviction. 1268 * will become fully unmapped and are eligible for eviction.
1269 * 1269 *
1270 * For very sparsely populated VMAs this is a little inefficient - chances are 1270 * For very sparsely populated VMAs this is a little inefficient - chances are
1271 * there there won't be many ptes located within the scan cluster. In this case 1271 * there there won't be many ptes located within the scan cluster. In this case
1272 * maybe we could scan further - to the end of the pte page, perhaps. 1272 * maybe we could scan further - to the end of the pte page, perhaps.
1273 * 1273 *
1274 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can 1274 * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can
1275 * acquire it without blocking. If vma locked, mlock the pages in the cluster, 1275 * acquire it without blocking. If vma locked, mlock the pages in the cluster,
1276 * rather than unmapping them. If we encounter the "check_page" that vmscan is 1276 * rather than unmapping them. If we encounter the "check_page" that vmscan is
1277 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. 1277 * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN.
1278 */ 1278 */
1279 #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) 1279 #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
1280 #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) 1280 #define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
1281 1281
1282 static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, 1282 static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount,
1283 struct vm_area_struct *vma, struct page *check_page) 1283 struct vm_area_struct *vma, struct page *check_page)
1284 { 1284 {
1285 struct mm_struct *mm = vma->vm_mm; 1285 struct mm_struct *mm = vma->vm_mm;
1286 pmd_t *pmd; 1286 pmd_t *pmd;
1287 pte_t *pte; 1287 pte_t *pte;
1288 pte_t pteval; 1288 pte_t pteval;
1289 spinlock_t *ptl; 1289 spinlock_t *ptl;
1290 struct page *page; 1290 struct page *page;
1291 unsigned long address; 1291 unsigned long address;
1292 unsigned long mmun_start; /* For mmu_notifiers */ 1292 unsigned long mmun_start; /* For mmu_notifiers */
1293 unsigned long mmun_end; /* For mmu_notifiers */ 1293 unsigned long mmun_end; /* For mmu_notifiers */
1294 unsigned long end; 1294 unsigned long end;
1295 int ret = SWAP_AGAIN; 1295 int ret = SWAP_AGAIN;
1296 int locked_vma = 0; 1296 int locked_vma = 0;
1297 1297
1298 address = (vma->vm_start + cursor) & CLUSTER_MASK; 1298 address = (vma->vm_start + cursor) & CLUSTER_MASK;
1299 end = address + CLUSTER_SIZE; 1299 end = address + CLUSTER_SIZE;
1300 if (address < vma->vm_start) 1300 if (address < vma->vm_start)
1301 address = vma->vm_start; 1301 address = vma->vm_start;
1302 if (end > vma->vm_end) 1302 if (end > vma->vm_end)
1303 end = vma->vm_end; 1303 end = vma->vm_end;
1304 1304
1305 pmd = mm_find_pmd(mm, address); 1305 pmd = mm_find_pmd(mm, address);
1306 if (!pmd) 1306 if (!pmd)
1307 return ret; 1307 return ret;
1308 1308
1309 mmun_start = address; 1309 mmun_start = address;
1310 mmun_end = end; 1310 mmun_end = end;
1311 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end); 1311 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
1312 1312
1313 /* 1313 /*
1314 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, 1314 * If we can acquire the mmap_sem for read, and vma is VM_LOCKED,
1315 * keep the sem while scanning the cluster for mlocking pages. 1315 * keep the sem while scanning the cluster for mlocking pages.
1316 */ 1316 */
1317 if (down_read_trylock(&vma->vm_mm->mmap_sem)) { 1317 if (down_read_trylock(&vma->vm_mm->mmap_sem)) {
1318 locked_vma = (vma->vm_flags & VM_LOCKED); 1318 locked_vma = (vma->vm_flags & VM_LOCKED);
1319 if (!locked_vma) 1319 if (!locked_vma)
1320 up_read(&vma->vm_mm->mmap_sem); /* don't need it */ 1320 up_read(&vma->vm_mm->mmap_sem); /* don't need it */
1321 } 1321 }
1322 1322
1323 pte = pte_offset_map_lock(mm, pmd, address, &ptl); 1323 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
1324 1324
1325 /* Update high watermark before we lower rss */ 1325 /* Update high watermark before we lower rss */
1326 update_hiwater_rss(mm); 1326 update_hiwater_rss(mm);
1327 1327
1328 for (; address < end; pte++, address += PAGE_SIZE) { 1328 for (; address < end; pte++, address += PAGE_SIZE) {
1329 if (!pte_present(*pte)) 1329 if (!pte_present(*pte))
1330 continue; 1330 continue;
1331 page = vm_normal_page(vma, address, *pte); 1331 page = vm_normal_page(vma, address, *pte);
1332 BUG_ON(!page || PageAnon(page)); 1332 BUG_ON(!page || PageAnon(page));
1333 1333
1334 if (locked_vma) { 1334 if (locked_vma) {
1335 if (page == check_page) { 1335 if (page == check_page) {
1336 /* we know we have check_page locked */ 1336 /* we know we have check_page locked */
1337 mlock_vma_page(page); 1337 mlock_vma_page(page);
1338 ret = SWAP_MLOCK; 1338 ret = SWAP_MLOCK;
1339 } else if (trylock_page(page)) { 1339 } else if (trylock_page(page)) {
1340 /* 1340 /*
1341 * If we can lock the page, perform mlock. 1341 * If we can lock the page, perform mlock.
1342 * Otherwise leave the page alone, it will be 1342 * Otherwise leave the page alone, it will be
1343 * eventually encountered again later. 1343 * eventually encountered again later.
1344 */ 1344 */
1345 mlock_vma_page(page); 1345 mlock_vma_page(page);
1346 unlock_page(page); 1346 unlock_page(page);
1347 } 1347 }
1348 continue; /* don't unmap */ 1348 continue; /* don't unmap */
1349 } 1349 }
1350 1350
1351 if (ptep_clear_flush_young_notify(vma, address, pte)) 1351 if (ptep_clear_flush_young_notify(vma, address, pte))
1352 continue; 1352 continue;
1353 1353
1354 /* Nuke the page table entry. */ 1354 /* Nuke the page table entry. */
1355 flush_cache_page(vma, address, pte_pfn(*pte)); 1355 flush_cache_page(vma, address, pte_pfn(*pte));
1356 pteval = ptep_clear_flush(vma, address, pte); 1356 pteval = ptep_clear_flush(vma, address, pte);
1357 1357
1358 /* If nonlinear, store the file page offset in the pte. */ 1358 /* If nonlinear, store the file page offset in the pte. */
1359 if (page->index != linear_page_index(vma, address)) { 1359 if (page->index != linear_page_index(vma, address)) {
1360 pte_t ptfile = pgoff_to_pte(page->index); 1360 pte_t ptfile = pgoff_to_pte(page->index);
1361 if (pte_soft_dirty(pteval)) 1361 if (pte_soft_dirty(pteval))
1362 pte_file_mksoft_dirty(ptfile); 1362 pte_file_mksoft_dirty(ptfile);
1363 set_pte_at(mm, address, pte, ptfile); 1363 set_pte_at(mm, address, pte, ptfile);
1364 } 1364 }
1365 1365
1366 /* Move the dirty bit to the physical page now the pte is gone. */ 1366 /* Move the dirty bit to the physical page now the pte is gone. */
1367 if (pte_dirty(pteval)) 1367 if (pte_dirty(pteval))
1368 set_page_dirty(page); 1368 set_page_dirty(page);
1369 1369
1370 page_remove_rmap(page); 1370 page_remove_rmap(page);
1371 page_cache_release(page); 1371 page_cache_release(page);
1372 dec_mm_counter(mm, MM_FILEPAGES); 1372 dec_mm_counter(mm, MM_FILEPAGES);
1373 (*mapcount)--; 1373 (*mapcount)--;
1374 } 1374 }
1375 pte_unmap_unlock(pte - 1, ptl); 1375 pte_unmap_unlock(pte - 1, ptl);
1376 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); 1376 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
1377 if (locked_vma) 1377 if (locked_vma)
1378 up_read(&vma->vm_mm->mmap_sem); 1378 up_read(&vma->vm_mm->mmap_sem);
1379 return ret; 1379 return ret;
1380 } 1380 }
1381 1381
1382 static int try_to_unmap_nonlinear(struct page *page, 1382 static int try_to_unmap_nonlinear(struct page *page,
1383 struct address_space *mapping, void *arg) 1383 struct address_space *mapping, void *arg)
1384 { 1384 {
1385 struct vm_area_struct *vma; 1385 struct vm_area_struct *vma;
1386 int ret = SWAP_AGAIN; 1386 int ret = SWAP_AGAIN;
1387 unsigned long cursor; 1387 unsigned long cursor;
1388 unsigned long max_nl_cursor = 0; 1388 unsigned long max_nl_cursor = 0;
1389 unsigned long max_nl_size = 0; 1389 unsigned long max_nl_size = 0;
1390 unsigned int mapcount; 1390 unsigned int mapcount;
1391 1391
1392 list_for_each_entry(vma, 1392 list_for_each_entry(vma,
1393 &mapping->i_mmap_nonlinear, shared.nonlinear) { 1393 &mapping->i_mmap_nonlinear, shared.nonlinear) {
1394 1394
1395 cursor = (unsigned long) vma->vm_private_data; 1395 cursor = (unsigned long) vma->vm_private_data;
1396 if (cursor > max_nl_cursor) 1396 if (cursor > max_nl_cursor)
1397 max_nl_cursor = cursor; 1397 max_nl_cursor = cursor;
1398 cursor = vma->vm_end - vma->vm_start; 1398 cursor = vma->vm_end - vma->vm_start;
1399 if (cursor > max_nl_size) 1399 if (cursor > max_nl_size)
1400 max_nl_size = cursor; 1400 max_nl_size = cursor;
1401 } 1401 }
1402 1402
1403 if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ 1403 if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */
1404 return SWAP_FAIL; 1404 return SWAP_FAIL;
1405 } 1405 }
1406 1406
1407 /* 1407 /*
1408 * We don't try to search for this page in the nonlinear vmas, 1408 * We don't try to search for this page in the nonlinear vmas,
1409 * and page_referenced wouldn't have found it anyway. Instead 1409 * and page_referenced wouldn't have found it anyway. Instead
1410 * just walk the nonlinear vmas trying to age and unmap some. 1410 * just walk the nonlinear vmas trying to age and unmap some.
1411 * The mapcount of the page we came in with is irrelevant, 1411 * The mapcount of the page we came in with is irrelevant,
1412 * but even so use it as a guide to how hard we should try? 1412 * but even so use it as a guide to how hard we should try?
1413 */ 1413 */
1414 mapcount = page_mapcount(page); 1414 mapcount = page_mapcount(page);
1415 if (!mapcount) 1415 if (!mapcount)
1416 return ret; 1416 return ret;
1417 1417
1418 cond_resched(); 1418 cond_resched();
1419 1419
1420 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; 1420 max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
1421 if (max_nl_cursor == 0) 1421 if (max_nl_cursor == 0)
1422 max_nl_cursor = CLUSTER_SIZE; 1422 max_nl_cursor = CLUSTER_SIZE;
1423 1423
1424 do { 1424 do {
1425 list_for_each_entry(vma, 1425 list_for_each_entry(vma,
1426 &mapping->i_mmap_nonlinear, shared.nonlinear) { 1426 &mapping->i_mmap_nonlinear, shared.nonlinear) {
1427 1427
1428 cursor = (unsigned long) vma->vm_private_data; 1428 cursor = (unsigned long) vma->vm_private_data;
1429 while (cursor < max_nl_cursor && 1429 while (cursor < max_nl_cursor &&
1430 cursor < vma->vm_end - vma->vm_start) { 1430 cursor < vma->vm_end - vma->vm_start) {
1431 if (try_to_unmap_cluster(cursor, &mapcount, 1431 if (try_to_unmap_cluster(cursor, &mapcount,
1432 vma, page) == SWAP_MLOCK) 1432 vma, page) == SWAP_MLOCK)
1433 ret = SWAP_MLOCK; 1433 ret = SWAP_MLOCK;
1434 cursor += CLUSTER_SIZE; 1434 cursor += CLUSTER_SIZE;
1435 vma->vm_private_data = (void *) cursor; 1435 vma->vm_private_data = (void *) cursor;
1436 if ((int)mapcount <= 0) 1436 if ((int)mapcount <= 0)
1437 return ret; 1437 return ret;
1438 } 1438 }
1439 vma->vm_private_data = (void *) max_nl_cursor; 1439 vma->vm_private_data = (void *) max_nl_cursor;
1440 } 1440 }
1441 cond_resched(); 1441 cond_resched();
1442 max_nl_cursor += CLUSTER_SIZE; 1442 max_nl_cursor += CLUSTER_SIZE;
1443 } while (max_nl_cursor <= max_nl_size); 1443 } while (max_nl_cursor <= max_nl_size);
1444 1444
1445 /* 1445 /*
1446 * Don't loop forever (perhaps all the remaining pages are 1446 * Don't loop forever (perhaps all the remaining pages are
1447 * in locked vmas). Reset cursor on all unreserved nonlinear 1447 * in locked vmas). Reset cursor on all unreserved nonlinear
1448 * vmas, now forgetting on which ones it had fallen behind. 1448 * vmas, now forgetting on which ones it had fallen behind.
1449 */ 1449 */
1450 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear) 1450 list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.nonlinear)
1451 vma->vm_private_data = NULL; 1451 vma->vm_private_data = NULL;
1452 1452
1453 return ret; 1453 return ret;
1454 } 1454 }
1455 1455
1456 bool is_vma_temporary_stack(struct vm_area_struct *vma) 1456 bool is_vma_temporary_stack(struct vm_area_struct *vma)
1457 { 1457 {
1458 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); 1458 int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP);
1459 1459
1460 if (!maybe_stack) 1460 if (!maybe_stack)
1461 return false; 1461 return false;
1462 1462
1463 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == 1463 if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) ==
1464 VM_STACK_INCOMPLETE_SETUP) 1464 VM_STACK_INCOMPLETE_SETUP)
1465 return true; 1465 return true;
1466 1466
1467 return false; 1467 return false;
1468 } 1468 }
1469 1469
1470 static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg) 1470 static bool invalid_migration_vma(struct vm_area_struct *vma, void *arg)
1471 { 1471 {
1472 return is_vma_temporary_stack(vma); 1472 return is_vma_temporary_stack(vma);
1473 } 1473 }
1474 1474
1475 static int page_not_mapped(struct page *page) 1475 static int page_not_mapped(struct page *page)
1476 { 1476 {
1477 return !page_mapped(page); 1477 return !page_mapped(page);
1478 }; 1478 };
1479 1479
1480 /** 1480 /**
1481 * try_to_unmap - try to remove all page table mappings to a page 1481 * try_to_unmap - try to remove all page table mappings to a page
1482 * @page: the page to get unmapped 1482 * @page: the page to get unmapped
1483 * @flags: action and flags 1483 * @flags: action and flags
1484 * 1484 *
1485 * Tries to remove all the page table entries which are mapping this 1485 * Tries to remove all the page table entries which are mapping this
1486 * page, used in the pageout path. Caller must hold the page lock. 1486 * page, used in the pageout path. Caller must hold the page lock.
1487 * Return values are: 1487 * Return values are:
1488 * 1488 *
1489 * SWAP_SUCCESS - we succeeded in removing all mappings 1489 * SWAP_SUCCESS - we succeeded in removing all mappings
1490 * SWAP_AGAIN - we missed a mapping, try again later 1490 * SWAP_AGAIN - we missed a mapping, try again later
1491 * SWAP_FAIL - the page is unswappable 1491 * SWAP_FAIL - the page is unswappable
1492 * SWAP_MLOCK - page is mlocked. 1492 * SWAP_MLOCK - page is mlocked.
1493 */ 1493 */
1494 int try_to_unmap(struct page *page, enum ttu_flags flags) 1494 int try_to_unmap(struct page *page, enum ttu_flags flags)
1495 { 1495 {
1496 int ret; 1496 int ret;
1497 struct rmap_walk_control rwc = { 1497 struct rmap_walk_control rwc = {
1498 .rmap_one = try_to_unmap_one, 1498 .rmap_one = try_to_unmap_one,
1499 .arg = (void *)flags, 1499 .arg = (void *)flags,
1500 .done = page_not_mapped, 1500 .done = page_not_mapped,
1501 .file_nonlinear = try_to_unmap_nonlinear, 1501 .file_nonlinear = try_to_unmap_nonlinear,
1502 .anon_lock = page_lock_anon_vma_read, 1502 .anon_lock = page_lock_anon_vma_read,
1503 }; 1503 };
1504 1504
1505 VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page); 1505 VM_BUG_ON_PAGE(!PageHuge(page) && PageTransHuge(page), page);
1506 1506
1507 /* 1507 /*
1508 * During exec, a temporary VMA is setup and later moved. 1508 * During exec, a temporary VMA is setup and later moved.
1509 * The VMA is moved under the anon_vma lock but not the 1509 * The VMA is moved under the anon_vma lock but not the
1510 * page tables leading to a race where migration cannot 1510 * page tables leading to a race where migration cannot
1511 * find the migration ptes. Rather than increasing the 1511 * find the migration ptes. Rather than increasing the
1512 * locking requirements of exec(), migration skips 1512 * locking requirements of exec(), migration skips
1513 * temporary VMAs until after exec() completes. 1513 * temporary VMAs until after exec() completes.
1514 */ 1514 */
1515 if (flags & TTU_MIGRATION && !PageKsm(page) && PageAnon(page)) 1515 if (flags & TTU_MIGRATION && !PageKsm(page) && PageAnon(page))
1516 rwc.invalid_vma = invalid_migration_vma; 1516 rwc.invalid_vma = invalid_migration_vma;
1517 1517
1518 ret = rmap_walk(page, &rwc); 1518 ret = rmap_walk(page, &rwc);
1519 1519
1520 if (ret != SWAP_MLOCK && !page_mapped(page)) 1520 if (ret != SWAP_MLOCK && !page_mapped(page))
1521 ret = SWAP_SUCCESS; 1521 ret = SWAP_SUCCESS;
1522 return ret; 1522 return ret;
1523 } 1523 }
1524 1524
1525 /** 1525 /**
1526 * try_to_munlock - try to munlock a page 1526 * try_to_munlock - try to munlock a page
1527 * @page: the page to be munlocked 1527 * @page: the page to be munlocked
1528 * 1528 *
1529 * Called from munlock code. Checks all of the VMAs mapping the page 1529 * Called from munlock code. Checks all of the VMAs mapping the page
1530 * to make sure nobody else has this page mlocked. The page will be 1530 * to make sure nobody else has this page mlocked. The page will be
1531 * returned with PG_mlocked cleared if no other vmas have it mlocked. 1531 * returned with PG_mlocked cleared if no other vmas have it mlocked.
1532 * 1532 *
1533 * Return values are: 1533 * Return values are:
1534 * 1534 *
1535 * SWAP_AGAIN - no vma is holding page mlocked, or, 1535 * SWAP_AGAIN - no vma is holding page mlocked, or,
1536 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem 1536 * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem
1537 * SWAP_FAIL - page cannot be located at present 1537 * SWAP_FAIL - page cannot be located at present
1538 * SWAP_MLOCK - page is now mlocked. 1538 * SWAP_MLOCK - page is now mlocked.
1539 */ 1539 */
1540 int try_to_munlock(struct page *page) 1540 int try_to_munlock(struct page *page)
1541 { 1541 {
1542 int ret; 1542 int ret;
1543 struct rmap_walk_control rwc = { 1543 struct rmap_walk_control rwc = {
1544 .rmap_one = try_to_unmap_one, 1544 .rmap_one = try_to_unmap_one,
1545 .arg = (void *)TTU_MUNLOCK, 1545 .arg = (void *)TTU_MUNLOCK,
1546 .done = page_not_mapped, 1546 .done = page_not_mapped,
1547 /* 1547 /*
1548 * We don't bother to try to find the munlocked page in 1548 * We don't bother to try to find the munlocked page in
1549 * nonlinears. It's costly. Instead, later, page reclaim logic 1549 * nonlinears. It's costly. Instead, later, page reclaim logic
1550 * may call try_to_unmap() and recover PG_mlocked lazily. 1550 * may call try_to_unmap() and recover PG_mlocked lazily.
1551 */ 1551 */
1552 .file_nonlinear = NULL, 1552 .file_nonlinear = NULL,
1553 .anon_lock = page_lock_anon_vma_read, 1553 .anon_lock = page_lock_anon_vma_read,
1554 1554
1555 }; 1555 };
1556 1556
1557 VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page); 1557 VM_BUG_ON_PAGE(!PageLocked(page) || PageLRU(page), page);
1558 1558
1559 ret = rmap_walk(page, &rwc); 1559 ret = rmap_walk(page, &rwc);
1560 return ret; 1560 return ret;
1561 } 1561 }
1562 1562
1563 void __put_anon_vma(struct anon_vma *anon_vma) 1563 void __put_anon_vma(struct anon_vma *anon_vma)
1564 { 1564 {
1565 struct anon_vma *root = anon_vma->root; 1565 struct anon_vma *root = anon_vma->root;
1566 1566
1567 anon_vma_free(anon_vma);
1567 if (root != anon_vma && atomic_dec_and_test(&root->refcount)) 1568 if (root != anon_vma && atomic_dec_and_test(&root->refcount))
1568 anon_vma_free(root); 1569 anon_vma_free(root);
1569
1570 anon_vma_free(anon_vma);
1571 } 1570 }
1572 1571
1573 static struct anon_vma *rmap_walk_anon_lock(struct page *page, 1572 static struct anon_vma *rmap_walk_anon_lock(struct page *page,
1574 struct rmap_walk_control *rwc) 1573 struct rmap_walk_control *rwc)
1575 { 1574 {
1576 struct anon_vma *anon_vma; 1575 struct anon_vma *anon_vma;
1577 1576
1578 if (rwc->anon_lock) 1577 if (rwc->anon_lock)
1579 return rwc->anon_lock(page); 1578 return rwc->anon_lock(page);
1580 1579
1581 /* 1580 /*
1582 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read() 1581 * Note: remove_migration_ptes() cannot use page_lock_anon_vma_read()
1583 * because that depends on page_mapped(); but not all its usages 1582 * because that depends on page_mapped(); but not all its usages
1584 * are holding mmap_sem. Users without mmap_sem are required to 1583 * are holding mmap_sem. Users without mmap_sem are required to
1585 * take a reference count to prevent the anon_vma disappearing 1584 * take a reference count to prevent the anon_vma disappearing
1586 */ 1585 */
1587 anon_vma = page_anon_vma(page); 1586 anon_vma = page_anon_vma(page);
1588 if (!anon_vma) 1587 if (!anon_vma)
1589 return NULL; 1588 return NULL;
1590 1589
1591 anon_vma_lock_read(anon_vma); 1590 anon_vma_lock_read(anon_vma);
1592 return anon_vma; 1591 return anon_vma;
1593 } 1592 }
1594 1593
1595 /* 1594 /*
1596 * rmap_walk_anon - do something to anonymous page using the object-based 1595 * rmap_walk_anon - do something to anonymous page using the object-based
1597 * rmap method 1596 * rmap method
1598 * @page: the page to be handled 1597 * @page: the page to be handled
1599 * @rwc: control variable according to each walk type 1598 * @rwc: control variable according to each walk type
1600 * 1599 *
1601 * Find all the mappings of a page using the mapping pointer and the vma chains 1600 * Find all the mappings of a page using the mapping pointer and the vma chains
1602 * contained in the anon_vma struct it points to. 1601 * contained in the anon_vma struct it points to.
1603 * 1602 *
1604 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma 1603 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1605 * where the page was found will be held for write. So, we won't recheck 1604 * where the page was found will be held for write. So, we won't recheck
1606 * vm_flags for that VMA. That should be OK, because that vma shouldn't be 1605 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1607 * LOCKED. 1606 * LOCKED.
1608 */ 1607 */
1609 static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc) 1608 static int rmap_walk_anon(struct page *page, struct rmap_walk_control *rwc)
1610 { 1609 {
1611 struct anon_vma *anon_vma; 1610 struct anon_vma *anon_vma;
1612 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); 1611 pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
1613 struct anon_vma_chain *avc; 1612 struct anon_vma_chain *avc;
1614 int ret = SWAP_AGAIN; 1613 int ret = SWAP_AGAIN;
1615 1614
1616 anon_vma = rmap_walk_anon_lock(page, rwc); 1615 anon_vma = rmap_walk_anon_lock(page, rwc);
1617 if (!anon_vma) 1616 if (!anon_vma)
1618 return ret; 1617 return ret;
1619 1618
1620 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) { 1619 anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {
1621 struct vm_area_struct *vma = avc->vma; 1620 struct vm_area_struct *vma = avc->vma;
1622 unsigned long address = vma_address(page, vma); 1621 unsigned long address = vma_address(page, vma);
1623 1622
1624 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) 1623 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1625 continue; 1624 continue;
1626 1625
1627 ret = rwc->rmap_one(page, vma, address, rwc->arg); 1626 ret = rwc->rmap_one(page, vma, address, rwc->arg);
1628 if (ret != SWAP_AGAIN) 1627 if (ret != SWAP_AGAIN)
1629 break; 1628 break;
1630 if (rwc->done && rwc->done(page)) 1629 if (rwc->done && rwc->done(page))
1631 break; 1630 break;
1632 } 1631 }
1633 anon_vma_unlock_read(anon_vma); 1632 anon_vma_unlock_read(anon_vma);
1634 return ret; 1633 return ret;
1635 } 1634 }
1636 1635
1637 /* 1636 /*
1638 * rmap_walk_file - do something to file page using the object-based rmap method 1637 * rmap_walk_file - do something to file page using the object-based rmap method
1639 * @page: the page to be handled 1638 * @page: the page to be handled
1640 * @rwc: control variable according to each walk type 1639 * @rwc: control variable according to each walk type
1641 * 1640 *
1642 * Find all the mappings of a page using the mapping pointer and the vma chains 1641 * Find all the mappings of a page using the mapping pointer and the vma chains
1643 * contained in the address_space struct it points to. 1642 * contained in the address_space struct it points to.
1644 * 1643 *
1645 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma 1644 * When called from try_to_munlock(), the mmap_sem of the mm containing the vma
1646 * where the page was found will be held for write. So, we won't recheck 1645 * where the page was found will be held for write. So, we won't recheck
1647 * vm_flags for that VMA. That should be OK, because that vma shouldn't be 1646 * vm_flags for that VMA. That should be OK, because that vma shouldn't be
1648 * LOCKED. 1647 * LOCKED.
1649 */ 1648 */
1650 static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc) 1649 static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
1651 { 1650 {
1652 struct address_space *mapping = page->mapping; 1651 struct address_space *mapping = page->mapping;
1653 pgoff_t pgoff = page->index << compound_order(page); 1652 pgoff_t pgoff = page->index << compound_order(page);
1654 struct vm_area_struct *vma; 1653 struct vm_area_struct *vma;
1655 int ret = SWAP_AGAIN; 1654 int ret = SWAP_AGAIN;
1656 1655
1657 /* 1656 /*
1658 * The page lock not only makes sure that page->mapping cannot 1657 * The page lock not only makes sure that page->mapping cannot
1659 * suddenly be NULLified by truncation, it makes sure that the 1658 * suddenly be NULLified by truncation, it makes sure that the
1660 * structure at mapping cannot be freed and reused yet, 1659 * structure at mapping cannot be freed and reused yet,
1661 * so we can safely take mapping->i_mmap_mutex. 1660 * so we can safely take mapping->i_mmap_mutex.
1662 */ 1661 */
1663 VM_BUG_ON(!PageLocked(page)); 1662 VM_BUG_ON(!PageLocked(page));
1664 1663
1665 if (!mapping) 1664 if (!mapping)
1666 return ret; 1665 return ret;
1667 mutex_lock(&mapping->i_mmap_mutex); 1666 mutex_lock(&mapping->i_mmap_mutex);
1668 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) { 1667 vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {
1669 unsigned long address = vma_address(page, vma); 1668 unsigned long address = vma_address(page, vma);
1670 1669
1671 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg)) 1670 if (rwc->invalid_vma && rwc->invalid_vma(vma, rwc->arg))
1672 continue; 1671 continue;
1673 1672
1674 ret = rwc->rmap_one(page, vma, address, rwc->arg); 1673 ret = rwc->rmap_one(page, vma, address, rwc->arg);
1675 if (ret != SWAP_AGAIN) 1674 if (ret != SWAP_AGAIN)
1676 goto done; 1675 goto done;
1677 if (rwc->done && rwc->done(page)) 1676 if (rwc->done && rwc->done(page))
1678 goto done; 1677 goto done;
1679 } 1678 }
1680 1679
1681 if (!rwc->file_nonlinear) 1680 if (!rwc->file_nonlinear)
1682 goto done; 1681 goto done;
1683 1682
1684 if (list_empty(&mapping->i_mmap_nonlinear)) 1683 if (list_empty(&mapping->i_mmap_nonlinear))
1685 goto done; 1684 goto done;
1686 1685
1687 ret = rwc->file_nonlinear(page, mapping, rwc->arg); 1686 ret = rwc->file_nonlinear(page, mapping, rwc->arg);
1688 1687
1689 done: 1688 done:
1690 mutex_unlock(&mapping->i_mmap_mutex); 1689 mutex_unlock(&mapping->i_mmap_mutex);
1691 return ret; 1690 return ret;
1692 } 1691 }
1693 1692
1694 int rmap_walk(struct page *page, struct rmap_walk_control *rwc) 1693 int rmap_walk(struct page *page, struct rmap_walk_control *rwc)
1695 { 1694 {
1696 if (unlikely(PageKsm(page))) 1695 if (unlikely(PageKsm(page)))
1697 return rmap_walk_ksm(page, rwc); 1696 return rmap_walk_ksm(page, rwc);
1698 else if (PageAnon(page)) 1697 else if (PageAnon(page))
1699 return rmap_walk_anon(page, rwc); 1698 return rmap_walk_anon(page, rwc);
1700 else 1699 else
1701 return rmap_walk_file(page, rwc); 1700 return rmap_walk_file(page, rwc);
1702 } 1701 }
1703 1702
1704 #ifdef CONFIG_HUGETLB_PAGE 1703 #ifdef CONFIG_HUGETLB_PAGE
1705 /* 1704 /*
1706 * The following three functions are for anonymous (private mapped) hugepages. 1705 * The following three functions are for anonymous (private mapped) hugepages.
1707 * Unlike common anonymous pages, anonymous hugepages have no accounting code 1706 * Unlike common anonymous pages, anonymous hugepages have no accounting code
1708 * and no lru code, because we handle hugepages differently from common pages. 1707 * and no lru code, because we handle hugepages differently from common pages.
1709 */ 1708 */
1710 static void __hugepage_set_anon_rmap(struct page *page, 1709 static void __hugepage_set_anon_rmap(struct page *page,
1711 struct vm_area_struct *vma, unsigned long address, int exclusive) 1710 struct vm_area_struct *vma, unsigned long address, int exclusive)
1712 { 1711 {
1713 struct anon_vma *anon_vma = vma->anon_vma; 1712 struct anon_vma *anon_vma = vma->anon_vma;
1714 1713
1715 BUG_ON(!anon_vma); 1714 BUG_ON(!anon_vma);
1716 1715
1717 if (PageAnon(page)) 1716 if (PageAnon(page))
1718 return; 1717 return;
1719 if (!exclusive) 1718 if (!exclusive)
1720 anon_vma = anon_vma->root; 1719 anon_vma = anon_vma->root;
1721 1720
1722 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; 1721 anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
1723 page->mapping = (struct address_space *) anon_vma; 1722 page->mapping = (struct address_space *) anon_vma;
1724 page->index = linear_page_index(vma, address); 1723 page->index = linear_page_index(vma, address);
1725 } 1724 }
1726 1725
1727 void hugepage_add_anon_rmap(struct page *page, 1726 void hugepage_add_anon_rmap(struct page *page,
1728 struct vm_area_struct *vma, unsigned long address) 1727 struct vm_area_struct *vma, unsigned long address)
1729 { 1728 {
1730 struct anon_vma *anon_vma = vma->anon_vma; 1729 struct anon_vma *anon_vma = vma->anon_vma;
1731 int first; 1730 int first;
1732 1731
1733 BUG_ON(!PageLocked(page)); 1732 BUG_ON(!PageLocked(page));
1734 BUG_ON(!anon_vma); 1733 BUG_ON(!anon_vma);
1735 /* address might be in next vma when migration races vma_adjust */ 1734 /* address might be in next vma when migration races vma_adjust */
1736 first = atomic_inc_and_test(&page->_mapcount); 1735 first = atomic_inc_and_test(&page->_mapcount);
1737 if (first) 1736 if (first)
1738 __hugepage_set_anon_rmap(page, vma, address, 0); 1737 __hugepage_set_anon_rmap(page, vma, address, 0);
1739 } 1738 }
1740 1739
1741 void hugepage_add_new_anon_rmap(struct page *page, 1740 void hugepage_add_new_anon_rmap(struct page *page,
1742 struct vm_area_struct *vma, unsigned long address) 1741 struct vm_area_struct *vma, unsigned long address)
1743 { 1742 {
1744 BUG_ON(address < vma->vm_start || address >= vma->vm_end); 1743 BUG_ON(address < vma->vm_start || address >= vma->vm_end);
1745 atomic_set(&page->_mapcount, 0); 1744 atomic_set(&page->_mapcount, 0);
1746 __hugepage_set_anon_rmap(page, vma, address, 1); 1745 __hugepage_set_anon_rmap(page, vma, address, 1);
1747 } 1746 }
1748 #endif /* CONFIG_HUGETLB_PAGE */ 1747 #endif /* CONFIG_HUGETLB_PAGE */