Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * mm/rmap.c - physical to virtual reverse mappings | |
3 | * | |
4 | * Copyright 2001, Rik van Riel <riel@conectiva.com.br> | |
5 | * Released under the General Public License (GPL). | |
6 | * | |
7 | * Simple, low overhead reverse mapping scheme. | |
8 | * Please try to keep this thing as modular as possible. | |
9 | * | |
10 | * Provides methods for unmapping each kind of mapped page: | |
11 | * the anon methods track anonymous pages, and | |
12 | * the file methods track pages belonging to an inode. | |
13 | * | |
14 | * Original design by Rik van Riel <riel@conectiva.com.br> 2001 | |
15 | * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 | |
16 | * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 | |
98f32602 | 17 | * Contributions by Hugh Dickins 2003, 2004 |
1da177e4 LT |
18 | */ |
19 | ||
20 | /* | |
21 | * Lock ordering in mm: | |
22 | * | |
1b1dcc1b | 23 | * inode->i_mutex (while writing or truncating, not reading or faulting) |
82591e6e NP |
24 | * inode->i_alloc_sem (vmtruncate_range) |
25 | * mm->mmap_sem | |
26 | * page->flags PG_locked (lock_page) | |
3d48ae45 | 27 | * mapping->i_mmap_mutex |
2b575eb6 | 28 | * anon_vma->mutex |
82591e6e NP |
29 | * mm->page_table_lock or pte_lock |
30 | * zone->lru_lock (in mark_page_accessed, isolate_lru_page) | |
31 | * swap_lock (in swap_duplicate, swap_info_get) | |
32 | * mmlist_lock (in mmput, drain_mmlist and others) | |
33 | * mapping->private_lock (in __set_page_dirty_buffers) | |
250df6ed | 34 | * inode->i_lock (in set_page_dirty's __mark_inode_dirty) |
a66979ab | 35 | * inode_wb_list_lock (in set_page_dirty's __mark_inode_dirty) |
82591e6e NP |
36 | * sb_lock (within inode_lock in fs/fs-writeback.c) |
37 | * mapping->tree_lock (widely used, in set_page_dirty, | |
38 | * in arch-dependent flush_dcache_mmap_lock, | |
a66979ab | 39 | * within inode_wb_list_lock in __sync_single_inode) |
6a46079c AK |
40 | * |
41 | * (code doesn't rely on that order so it could be switched around) | |
42 | * ->tasklist_lock | |
2b575eb6 | 43 | * anon_vma->mutex (memory_failure, collect_procs_anon) |
6a46079c | 44 | * pte map lock |
1da177e4 LT |
45 | */ |
46 | ||
47 | #include <linux/mm.h> | |
48 | #include <linux/pagemap.h> | |
49 | #include <linux/swap.h> | |
50 | #include <linux/swapops.h> | |
51 | #include <linux/slab.h> | |
52 | #include <linux/init.h> | |
5ad64688 | 53 | #include <linux/ksm.h> |
1da177e4 LT |
54 | #include <linux/rmap.h> |
55 | #include <linux/rcupdate.h> | |
a48d07af | 56 | #include <linux/module.h> |
8a9f3ccd | 57 | #include <linux/memcontrol.h> |
cddb8a5c | 58 | #include <linux/mmu_notifier.h> |
64cdd548 | 59 | #include <linux/migrate.h> |
0fe6e20b | 60 | #include <linux/hugetlb.h> |
1da177e4 LT |
61 | |
62 | #include <asm/tlbflush.h> | |
63 | ||
b291f000 NP |
64 | #include "internal.h" |
65 | ||
fdd2e5f8 | 66 | static struct kmem_cache *anon_vma_cachep; |
5beb4930 | 67 | static struct kmem_cache *anon_vma_chain_cachep; |
fdd2e5f8 AB |
68 | |
69 | static inline struct anon_vma *anon_vma_alloc(void) | |
70 | { | |
01d8b20d PZ |
71 | struct anon_vma *anon_vma; |
72 | ||
73 | anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); | |
74 | if (anon_vma) { | |
75 | atomic_set(&anon_vma->refcount, 1); | |
76 | /* | |
77 | * Initialise the anon_vma root to point to itself. If called | |
78 | * from fork, the root will be reset to the parents anon_vma. | |
79 | */ | |
80 | anon_vma->root = anon_vma; | |
81 | } | |
82 | ||
83 | return anon_vma; | |
fdd2e5f8 AB |
84 | } |
85 | ||
01d8b20d | 86 | static inline void anon_vma_free(struct anon_vma *anon_vma) |
fdd2e5f8 | 87 | { |
01d8b20d | 88 | VM_BUG_ON(atomic_read(&anon_vma->refcount)); |
88c22088 PZ |
89 | |
90 | /* | |
91 | * Synchronize against page_lock_anon_vma() such that | |
92 | * we can safely hold the lock without the anon_vma getting | |
93 | * freed. | |
94 | * | |
95 | * Relies on the full mb implied by the atomic_dec_and_test() from | |
96 | * put_anon_vma() against the acquire barrier implied by | |
97 | * mutex_trylock() from page_lock_anon_vma(). This orders: | |
98 | * | |
99 | * page_lock_anon_vma() VS put_anon_vma() | |
100 | * mutex_trylock() atomic_dec_and_test() | |
101 | * LOCK MB | |
102 | * atomic_read() mutex_is_locked() | |
103 | * | |
104 | * LOCK should suffice since the actual taking of the lock must | |
105 | * happen _before_ what follows. | |
106 | */ | |
107 | if (mutex_is_locked(&anon_vma->root->mutex)) { | |
108 | anon_vma_lock(anon_vma); | |
109 | anon_vma_unlock(anon_vma); | |
110 | } | |
111 | ||
fdd2e5f8 AB |
112 | kmem_cache_free(anon_vma_cachep, anon_vma); |
113 | } | |
1da177e4 | 114 | |
5beb4930 RR |
115 | static inline struct anon_vma_chain *anon_vma_chain_alloc(void) |
116 | { | |
117 | return kmem_cache_alloc(anon_vma_chain_cachep, GFP_KERNEL); | |
118 | } | |
119 | ||
e574b5fd | 120 | static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) |
5beb4930 RR |
121 | { |
122 | kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); | |
123 | } | |
124 | ||
d9d332e0 LT |
125 | /** |
126 | * anon_vma_prepare - attach an anon_vma to a memory region | |
127 | * @vma: the memory region in question | |
128 | * | |
129 | * This makes sure the memory mapping described by 'vma' has | |
130 | * an 'anon_vma' attached to it, so that we can associate the | |
131 | * anonymous pages mapped into it with that anon_vma. | |
132 | * | |
133 | * The common case will be that we already have one, but if | |
23a0790a | 134 | * not we either need to find an adjacent mapping that we |
d9d332e0 LT |
135 | * can re-use the anon_vma from (very common when the only |
136 | * reason for splitting a vma has been mprotect()), or we | |
137 | * allocate a new one. | |
138 | * | |
139 | * Anon-vma allocations are very subtle, because we may have | |
140 | * optimistically looked up an anon_vma in page_lock_anon_vma() | |
141 | * and that may actually touch the spinlock even in the newly | |
142 | * allocated vma (it depends on RCU to make sure that the | |
143 | * anon_vma isn't actually destroyed). | |
144 | * | |
145 | * As a result, we need to do proper anon_vma locking even | |
146 | * for the new allocation. At the same time, we do not want | |
147 | * to do any locking for the common case of already having | |
148 | * an anon_vma. | |
149 | * | |
150 | * This must be called with the mmap_sem held for reading. | |
151 | */ | |
1da177e4 LT |
152 | int anon_vma_prepare(struct vm_area_struct *vma) |
153 | { | |
154 | struct anon_vma *anon_vma = vma->anon_vma; | |
5beb4930 | 155 | struct anon_vma_chain *avc; |
1da177e4 LT |
156 | |
157 | might_sleep(); | |
158 | if (unlikely(!anon_vma)) { | |
159 | struct mm_struct *mm = vma->vm_mm; | |
d9d332e0 | 160 | struct anon_vma *allocated; |
1da177e4 | 161 | |
5beb4930 RR |
162 | avc = anon_vma_chain_alloc(); |
163 | if (!avc) | |
164 | goto out_enomem; | |
165 | ||
1da177e4 | 166 | anon_vma = find_mergeable_anon_vma(vma); |
d9d332e0 LT |
167 | allocated = NULL; |
168 | if (!anon_vma) { | |
1da177e4 LT |
169 | anon_vma = anon_vma_alloc(); |
170 | if (unlikely(!anon_vma)) | |
5beb4930 | 171 | goto out_enomem_free_avc; |
1da177e4 | 172 | allocated = anon_vma; |
1da177e4 LT |
173 | } |
174 | ||
cba48b98 | 175 | anon_vma_lock(anon_vma); |
1da177e4 LT |
176 | /* page_table_lock to protect against threads */ |
177 | spin_lock(&mm->page_table_lock); | |
178 | if (likely(!vma->anon_vma)) { | |
179 | vma->anon_vma = anon_vma; | |
5beb4930 RR |
180 | avc->anon_vma = anon_vma; |
181 | avc->vma = vma; | |
182 | list_add(&avc->same_vma, &vma->anon_vma_chain); | |
26ba0cb6 | 183 | list_add_tail(&avc->same_anon_vma, &anon_vma->head); |
1da177e4 | 184 | allocated = NULL; |
31f2b0eb | 185 | avc = NULL; |
1da177e4 LT |
186 | } |
187 | spin_unlock(&mm->page_table_lock); | |
cba48b98 | 188 | anon_vma_unlock(anon_vma); |
31f2b0eb ON |
189 | |
190 | if (unlikely(allocated)) | |
01d8b20d | 191 | put_anon_vma(allocated); |
31f2b0eb | 192 | if (unlikely(avc)) |
5beb4930 | 193 | anon_vma_chain_free(avc); |
1da177e4 LT |
194 | } |
195 | return 0; | |
5beb4930 RR |
196 | |
197 | out_enomem_free_avc: | |
198 | anon_vma_chain_free(avc); | |
199 | out_enomem: | |
200 | return -ENOMEM; | |
1da177e4 LT |
201 | } |
202 | ||
5beb4930 RR |
203 | static void anon_vma_chain_link(struct vm_area_struct *vma, |
204 | struct anon_vma_chain *avc, | |
205 | struct anon_vma *anon_vma) | |
1da177e4 | 206 | { |
5beb4930 RR |
207 | avc->vma = vma; |
208 | avc->anon_vma = anon_vma; | |
209 | list_add(&avc->same_vma, &vma->anon_vma_chain); | |
210 | ||
cba48b98 | 211 | anon_vma_lock(anon_vma); |
05759d38 AA |
212 | /* |
213 | * It's critical to add new vmas to the tail of the anon_vma, | |
214 | * see comment in huge_memory.c:__split_huge_page(). | |
215 | */ | |
5beb4930 | 216 | list_add_tail(&avc->same_anon_vma, &anon_vma->head); |
cba48b98 | 217 | anon_vma_unlock(anon_vma); |
1da177e4 LT |
218 | } |
219 | ||
5beb4930 RR |
220 | /* |
221 | * Attach the anon_vmas from src to dst. | |
222 | * Returns 0 on success, -ENOMEM on failure. | |
223 | */ | |
224 | int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) | |
1da177e4 | 225 | { |
5beb4930 RR |
226 | struct anon_vma_chain *avc, *pavc; |
227 | ||
646d87b4 | 228 | list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { |
5beb4930 RR |
229 | avc = anon_vma_chain_alloc(); |
230 | if (!avc) | |
231 | goto enomem_failure; | |
232 | anon_vma_chain_link(dst, avc, pavc->anon_vma); | |
233 | } | |
234 | return 0; | |
1da177e4 | 235 | |
5beb4930 RR |
236 | enomem_failure: |
237 | unlink_anon_vmas(dst); | |
238 | return -ENOMEM; | |
1da177e4 LT |
239 | } |
240 | ||
5beb4930 RR |
241 | /* |
242 | * Attach vma to its own anon_vma, as well as to the anon_vmas that | |
243 | * the corresponding VMA in the parent process is attached to. | |
244 | * Returns 0 on success, non-zero on failure. | |
245 | */ | |
246 | int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) | |
1da177e4 | 247 | { |
5beb4930 RR |
248 | struct anon_vma_chain *avc; |
249 | struct anon_vma *anon_vma; | |
1da177e4 | 250 | |
5beb4930 RR |
251 | /* Don't bother if the parent process has no anon_vma here. */ |
252 | if (!pvma->anon_vma) | |
253 | return 0; | |
254 | ||
255 | /* | |
256 | * First, attach the new VMA to the parent VMA's anon_vmas, | |
257 | * so rmap can find non-COWed pages in child processes. | |
258 | */ | |
259 | if (anon_vma_clone(vma, pvma)) | |
260 | return -ENOMEM; | |
261 | ||
262 | /* Then add our own anon_vma. */ | |
263 | anon_vma = anon_vma_alloc(); | |
264 | if (!anon_vma) | |
265 | goto out_error; | |
266 | avc = anon_vma_chain_alloc(); | |
267 | if (!avc) | |
268 | goto out_error_free_anon_vma; | |
5c341ee1 RR |
269 | |
270 | /* | |
271 | * The root anon_vma's spinlock is the lock actually used when we | |
272 | * lock any of the anon_vmas in this anon_vma tree. | |
273 | */ | |
274 | anon_vma->root = pvma->anon_vma->root; | |
76545066 | 275 | /* |
01d8b20d PZ |
276 | * With refcounts, an anon_vma can stay around longer than the |
277 | * process it belongs to. The root anon_vma needs to be pinned until | |
278 | * this anon_vma is freed, because the lock lives in the root. | |
76545066 RR |
279 | */ |
280 | get_anon_vma(anon_vma->root); | |
5beb4930 RR |
281 | /* Mark this anon_vma as the one where our new (COWed) pages go. */ |
282 | vma->anon_vma = anon_vma; | |
5c341ee1 | 283 | anon_vma_chain_link(vma, avc, anon_vma); |
5beb4930 RR |
284 | |
285 | return 0; | |
286 | ||
287 | out_error_free_anon_vma: | |
01d8b20d | 288 | put_anon_vma(anon_vma); |
5beb4930 | 289 | out_error: |
4946d54c | 290 | unlink_anon_vmas(vma); |
5beb4930 | 291 | return -ENOMEM; |
1da177e4 LT |
292 | } |
293 | ||
5beb4930 | 294 | static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain) |
1da177e4 | 295 | { |
5beb4930 | 296 | struct anon_vma *anon_vma = anon_vma_chain->anon_vma; |
1da177e4 LT |
297 | int empty; |
298 | ||
5beb4930 | 299 | /* If anon_vma_fork fails, we can get an empty anon_vma_chain. */ |
1da177e4 LT |
300 | if (!anon_vma) |
301 | return; | |
302 | ||
cba48b98 | 303 | anon_vma_lock(anon_vma); |
5beb4930 | 304 | list_del(&anon_vma_chain->same_anon_vma); |
1da177e4 LT |
305 | |
306 | /* We must garbage collect the anon_vma if it's empty */ | |
01d8b20d | 307 | empty = list_empty(&anon_vma->head); |
cba48b98 | 308 | anon_vma_unlock(anon_vma); |
1da177e4 | 309 | |
01d8b20d PZ |
310 | if (empty) |
311 | put_anon_vma(anon_vma); | |
1da177e4 LT |
312 | } |
313 | ||
5beb4930 RR |
314 | void unlink_anon_vmas(struct vm_area_struct *vma) |
315 | { | |
316 | struct anon_vma_chain *avc, *next; | |
317 | ||
5c341ee1 RR |
318 | /* |
319 | * Unlink each anon_vma chained to the VMA. This list is ordered | |
320 | * from newest to oldest, ensuring the root anon_vma gets freed last. | |
321 | */ | |
5beb4930 RR |
322 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
323 | anon_vma_unlink(avc); | |
324 | list_del(&avc->same_vma); | |
325 | anon_vma_chain_free(avc); | |
326 | } | |
327 | } | |
328 | ||
51cc5068 | 329 | static void anon_vma_ctor(void *data) |
1da177e4 | 330 | { |
a35afb83 | 331 | struct anon_vma *anon_vma = data; |
1da177e4 | 332 | |
2b575eb6 | 333 | mutex_init(&anon_vma->mutex); |
83813267 | 334 | atomic_set(&anon_vma->refcount, 0); |
a35afb83 | 335 | INIT_LIST_HEAD(&anon_vma->head); |
1da177e4 LT |
336 | } |
337 | ||
338 | void __init anon_vma_init(void) | |
339 | { | |
340 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 341 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
5beb4930 | 342 | anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC); |
1da177e4 LT |
343 | } |
344 | ||
345 | /* | |
6111e4ca PZ |
346 | * Getting a lock on a stable anon_vma from a page off the LRU is tricky! |
347 | * | |
348 | * Since there is no serialization what so ever against page_remove_rmap() | |
349 | * the best this function can do is return a locked anon_vma that might | |
350 | * have been relevant to this page. | |
351 | * | |
352 | * The page might have been remapped to a different anon_vma or the anon_vma | |
353 | * returned may already be freed (and even reused). | |
354 | * | |
355 | * All users of this function must be very careful when walking the anon_vma | |
356 | * chain and verify that the page in question is indeed mapped in it | |
357 | * [ something equivalent to page_mapped_in_vma() ]. | |
358 | * | |
359 | * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap() | |
360 | * that the anon_vma pointer from page->mapping is valid if there is a | |
361 | * mapcount, we can dereference the anon_vma after observing those. | |
1da177e4 | 362 | */ |
746b18d4 | 363 | struct anon_vma *page_get_anon_vma(struct page *page) |
1da177e4 | 364 | { |
746b18d4 | 365 | struct anon_vma *anon_vma = NULL; |
1da177e4 LT |
366 | unsigned long anon_mapping; |
367 | ||
368 | rcu_read_lock(); | |
80e14822 | 369 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
3ca7b3c5 | 370 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
1da177e4 LT |
371 | goto out; |
372 | if (!page_mapped(page)) | |
373 | goto out; | |
374 | ||
375 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
746b18d4 PZ |
376 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { |
377 | anon_vma = NULL; | |
378 | goto out; | |
379 | } | |
f1819427 HD |
380 | |
381 | /* | |
382 | * If this page is still mapped, then its anon_vma cannot have been | |
746b18d4 PZ |
383 | * freed. But if it has been unmapped, we have no security against the |
384 | * anon_vma structure being freed and reused (for another anon_vma: | |
385 | * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero() | |
386 | * above cannot corrupt). | |
f1819427 | 387 | */ |
746b18d4 PZ |
388 | if (!page_mapped(page)) { |
389 | put_anon_vma(anon_vma); | |
390 | anon_vma = NULL; | |
391 | } | |
1da177e4 LT |
392 | out: |
393 | rcu_read_unlock(); | |
746b18d4 PZ |
394 | |
395 | return anon_vma; | |
396 | } | |
397 | ||
88c22088 PZ |
398 | /* |
399 | * Similar to page_get_anon_vma() except it locks the anon_vma. | |
400 | * | |
401 | * Its a little more complex as it tries to keep the fast path to a single | |
402 | * atomic op -- the trylock. If we fail the trylock, we fall back to getting a | |
403 | * reference like with page_get_anon_vma() and then block on the mutex. | |
404 | */ | |
746b18d4 PZ |
405 | struct anon_vma *page_lock_anon_vma(struct page *page) |
406 | { | |
88c22088 | 407 | struct anon_vma *anon_vma = NULL; |
eee0f252 | 408 | struct anon_vma *root_anon_vma; |
88c22088 | 409 | unsigned long anon_mapping; |
746b18d4 | 410 | |
88c22088 PZ |
411 | rcu_read_lock(); |
412 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); | |
413 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) | |
414 | goto out; | |
415 | if (!page_mapped(page)) | |
416 | goto out; | |
417 | ||
418 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
eee0f252 HD |
419 | root_anon_vma = ACCESS_ONCE(anon_vma->root); |
420 | if (mutex_trylock(&root_anon_vma->mutex)) { | |
88c22088 | 421 | /* |
eee0f252 HD |
422 | * If the page is still mapped, then this anon_vma is still |
423 | * its anon_vma, and holding the mutex ensures that it will | |
424 | * not go away, see __put_anon_vma(). | |
88c22088 | 425 | */ |
eee0f252 HD |
426 | if (!page_mapped(page)) { |
427 | mutex_unlock(&root_anon_vma->mutex); | |
88c22088 PZ |
428 | anon_vma = NULL; |
429 | } | |
430 | goto out; | |
431 | } | |
746b18d4 | 432 | |
88c22088 PZ |
433 | /* trylock failed, we got to sleep */ |
434 | if (!atomic_inc_not_zero(&anon_vma->refcount)) { | |
435 | anon_vma = NULL; | |
436 | goto out; | |
437 | } | |
438 | ||
439 | if (!page_mapped(page)) { | |
440 | put_anon_vma(anon_vma); | |
441 | anon_vma = NULL; | |
442 | goto out; | |
443 | } | |
444 | ||
445 | /* we pinned the anon_vma, its safe to sleep */ | |
446 | rcu_read_unlock(); | |
447 | anon_vma_lock(anon_vma); | |
448 | ||
449 | if (atomic_dec_and_test(&anon_vma->refcount)) { | |
450 | /* | |
451 | * Oops, we held the last refcount, release the lock | |
452 | * and bail -- can't simply use put_anon_vma() because | |
453 | * we'll deadlock on the anon_vma_lock() recursion. | |
454 | */ | |
455 | anon_vma_unlock(anon_vma); | |
456 | __put_anon_vma(anon_vma); | |
457 | anon_vma = NULL; | |
458 | } | |
459 | ||
460 | return anon_vma; | |
461 | ||
462 | out: | |
463 | rcu_read_unlock(); | |
746b18d4 | 464 | return anon_vma; |
34bbd704 ON |
465 | } |
466 | ||
10be22df | 467 | void page_unlock_anon_vma(struct anon_vma *anon_vma) |
34bbd704 | 468 | { |
cba48b98 | 469 | anon_vma_unlock(anon_vma); |
1da177e4 LT |
470 | } |
471 | ||
472 | /* | |
3ad33b24 LS |
473 | * At what user virtual address is page expected in @vma? |
474 | * Returns virtual address or -EFAULT if page's index/offset is not | |
475 | * within the range mapped the @vma. | |
1da177e4 | 476 | */ |
71e3aac0 | 477 | inline unsigned long |
1da177e4 LT |
478 | vma_address(struct page *page, struct vm_area_struct *vma) |
479 | { | |
480 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
481 | unsigned long address; | |
482 | ||
0fe6e20b NH |
483 | if (unlikely(is_vm_hugetlb_page(vma))) |
484 | pgoff = page->index << huge_page_order(page_hstate(page)); | |
1da177e4 LT |
485 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
486 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { | |
3ad33b24 | 487 | /* page should be within @vma mapping range */ |
1da177e4 LT |
488 | return -EFAULT; |
489 | } | |
490 | return address; | |
491 | } | |
492 | ||
493 | /* | |
bf89c8c8 | 494 | * At what user virtual address is page expected in vma? |
ab941e0f | 495 | * Caller should check the page is actually part of the vma. |
1da177e4 LT |
496 | */ |
497 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
498 | { | |
21d0d443 | 499 | if (PageAnon(page)) { |
4829b906 HD |
500 | struct anon_vma *page__anon_vma = page_anon_vma(page); |
501 | /* | |
502 | * Note: swapoff's unuse_vma() is more efficient with this | |
503 | * check, and needs it to match anon_vma when KSM is active. | |
504 | */ | |
505 | if (!vma->anon_vma || !page__anon_vma || | |
506 | vma->anon_vma->root != page__anon_vma->root) | |
21d0d443 AA |
507 | return -EFAULT; |
508 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
509 | if (!vma->vm_file || |
510 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
511 | return -EFAULT; |
512 | } else | |
513 | return -EFAULT; | |
514 | return vma_address(page, vma); | |
515 | } | |
516 | ||
81b4082d ND |
517 | /* |
518 | * Check that @page is mapped at @address into @mm. | |
519 | * | |
479db0bf NP |
520 | * If @sync is false, page_check_address may perform a racy check to avoid |
521 | * the page table lock when the pte is not present (helpful when reclaiming | |
522 | * highly shared pages). | |
523 | * | |
b8072f09 | 524 | * On success returns with pte mapped and locked. |
81b4082d | 525 | */ |
e9a81a82 | 526 | pte_t *__page_check_address(struct page *page, struct mm_struct *mm, |
479db0bf | 527 | unsigned long address, spinlock_t **ptlp, int sync) |
81b4082d ND |
528 | { |
529 | pgd_t *pgd; | |
530 | pud_t *pud; | |
531 | pmd_t *pmd; | |
532 | pte_t *pte; | |
c0718806 | 533 | spinlock_t *ptl; |
81b4082d | 534 | |
0fe6e20b NH |
535 | if (unlikely(PageHuge(page))) { |
536 | pte = huge_pte_offset(mm, address); | |
537 | ptl = &mm->page_table_lock; | |
538 | goto check; | |
539 | } | |
540 | ||
81b4082d | 541 | pgd = pgd_offset(mm, address); |
c0718806 HD |
542 | if (!pgd_present(*pgd)) |
543 | return NULL; | |
544 | ||
545 | pud = pud_offset(pgd, address); | |
546 | if (!pud_present(*pud)) | |
547 | return NULL; | |
548 | ||
549 | pmd = pmd_offset(pud, address); | |
550 | if (!pmd_present(*pmd)) | |
551 | return NULL; | |
71e3aac0 AA |
552 | if (pmd_trans_huge(*pmd)) |
553 | return NULL; | |
c0718806 HD |
554 | |
555 | pte = pte_offset_map(pmd, address); | |
556 | /* Make a quick check before getting the lock */ | |
479db0bf | 557 | if (!sync && !pte_present(*pte)) { |
c0718806 HD |
558 | pte_unmap(pte); |
559 | return NULL; | |
560 | } | |
561 | ||
4c21e2f2 | 562 | ptl = pte_lockptr(mm, pmd); |
0fe6e20b | 563 | check: |
c0718806 HD |
564 | spin_lock(ptl); |
565 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
566 | *ptlp = ptl; | |
567 | return pte; | |
81b4082d | 568 | } |
c0718806 HD |
569 | pte_unmap_unlock(pte, ptl); |
570 | return NULL; | |
81b4082d ND |
571 | } |
572 | ||
b291f000 NP |
573 | /** |
574 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
575 | * @page: the page to test | |
576 | * @vma: the VMA to test | |
577 | * | |
578 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
579 | * if the page is not mapped into the page tables of this VMA. Only | |
580 | * valid for normal file or anonymous VMAs. | |
581 | */ | |
6a46079c | 582 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) |
b291f000 NP |
583 | { |
584 | unsigned long address; | |
585 | pte_t *pte; | |
586 | spinlock_t *ptl; | |
587 | ||
588 | address = vma_address(page, vma); | |
589 | if (address == -EFAULT) /* out of vma range */ | |
590 | return 0; | |
591 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); | |
592 | if (!pte) /* the page is not in this mm */ | |
593 | return 0; | |
594 | pte_unmap_unlock(pte, ptl); | |
595 | ||
596 | return 1; | |
597 | } | |
598 | ||
1da177e4 LT |
599 | /* |
600 | * Subfunctions of page_referenced: page_referenced_one called | |
601 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
602 | */ | |
5ad64688 HD |
603 | int page_referenced_one(struct page *page, struct vm_area_struct *vma, |
604 | unsigned long address, unsigned int *mapcount, | |
605 | unsigned long *vm_flags) | |
1da177e4 LT |
606 | { |
607 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 LT |
608 | int referenced = 0; |
609 | ||
71e3aac0 AA |
610 | if (unlikely(PageTransHuge(page))) { |
611 | pmd_t *pmd; | |
612 | ||
613 | spin_lock(&mm->page_table_lock); | |
2da28bfd AA |
614 | /* |
615 | * rmap might return false positives; we must filter | |
616 | * these out using page_check_address_pmd(). | |
617 | */ | |
71e3aac0 AA |
618 | pmd = page_check_address_pmd(page, mm, address, |
619 | PAGE_CHECK_ADDRESS_PMD_FLAG); | |
2da28bfd AA |
620 | if (!pmd) { |
621 | spin_unlock(&mm->page_table_lock); | |
622 | goto out; | |
623 | } | |
624 | ||
625 | if (vma->vm_flags & VM_LOCKED) { | |
626 | spin_unlock(&mm->page_table_lock); | |
627 | *mapcount = 0; /* break early from loop */ | |
628 | *vm_flags |= VM_LOCKED; | |
629 | goto out; | |
630 | } | |
631 | ||
632 | /* go ahead even if the pmd is pmd_trans_splitting() */ | |
633 | if (pmdp_clear_flush_young_notify(vma, address, pmd)) | |
71e3aac0 AA |
634 | referenced++; |
635 | spin_unlock(&mm->page_table_lock); | |
636 | } else { | |
637 | pte_t *pte; | |
638 | spinlock_t *ptl; | |
639 | ||
2da28bfd AA |
640 | /* |
641 | * rmap might return false positives; we must filter | |
642 | * these out using page_check_address(). | |
643 | */ | |
71e3aac0 AA |
644 | pte = page_check_address(page, mm, address, &ptl, 0); |
645 | if (!pte) | |
646 | goto out; | |
647 | ||
2da28bfd AA |
648 | if (vma->vm_flags & VM_LOCKED) { |
649 | pte_unmap_unlock(pte, ptl); | |
650 | *mapcount = 0; /* break early from loop */ | |
651 | *vm_flags |= VM_LOCKED; | |
652 | goto out; | |
653 | } | |
654 | ||
71e3aac0 AA |
655 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
656 | /* | |
657 | * Don't treat a reference through a sequentially read | |
658 | * mapping as such. If the page has been used in | |
659 | * another mapping, we will catch it; if this other | |
660 | * mapping is already gone, the unmap path will have | |
661 | * set PG_referenced or activated the page. | |
662 | */ | |
663 | if (likely(!VM_SequentialReadHint(vma))) | |
664 | referenced++; | |
665 | } | |
666 | pte_unmap_unlock(pte, ptl); | |
667 | } | |
668 | ||
2da28bfd AA |
669 | /* Pretend the page is referenced if the task has the |
670 | swap token and is in the middle of a page fault. */ | |
671 | if (mm != current->mm && has_swap_token(mm) && | |
672 | rwsem_is_locked(&mm->mmap_sem)) | |
673 | referenced++; | |
674 | ||
c0718806 | 675 | (*mapcount)--; |
273f047e | 676 | |
6fe6b7e3 WF |
677 | if (referenced) |
678 | *vm_flags |= vma->vm_flags; | |
273f047e | 679 | out: |
1da177e4 LT |
680 | return referenced; |
681 | } | |
682 | ||
bed7161a | 683 | static int page_referenced_anon(struct page *page, |
6fe6b7e3 WF |
684 | struct mem_cgroup *mem_cont, |
685 | unsigned long *vm_flags) | |
1da177e4 LT |
686 | { |
687 | unsigned int mapcount; | |
688 | struct anon_vma *anon_vma; | |
5beb4930 | 689 | struct anon_vma_chain *avc; |
1da177e4 LT |
690 | int referenced = 0; |
691 | ||
692 | anon_vma = page_lock_anon_vma(page); | |
693 | if (!anon_vma) | |
694 | return referenced; | |
695 | ||
696 | mapcount = page_mapcount(page); | |
5beb4930 RR |
697 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
698 | struct vm_area_struct *vma = avc->vma; | |
1cb1729b HD |
699 | unsigned long address = vma_address(page, vma); |
700 | if (address == -EFAULT) | |
701 | continue; | |
bed7161a BS |
702 | /* |
703 | * If we are reclaiming on behalf of a cgroup, skip | |
704 | * counting on behalf of references from different | |
705 | * cgroups | |
706 | */ | |
bd845e38 | 707 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 708 | continue; |
1cb1729b | 709 | referenced += page_referenced_one(page, vma, address, |
6fe6b7e3 | 710 | &mapcount, vm_flags); |
1da177e4 LT |
711 | if (!mapcount) |
712 | break; | |
713 | } | |
34bbd704 ON |
714 | |
715 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
716 | return referenced; |
717 | } | |
718 | ||
719 | /** | |
720 | * page_referenced_file - referenced check for object-based rmap | |
721 | * @page: the page we're checking references on. | |
43d8eac4 | 722 | * @mem_cont: target memory controller |
6fe6b7e3 | 723 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
724 | * |
725 | * For an object-based mapped page, find all the places it is mapped and | |
726 | * check/clear the referenced flag. This is done by following the page->mapping | |
727 | * pointer, then walking the chain of vmas it holds. It returns the number | |
728 | * of references it found. | |
729 | * | |
730 | * This function is only called from page_referenced for object-based pages. | |
731 | */ | |
bed7161a | 732 | static int page_referenced_file(struct page *page, |
6fe6b7e3 WF |
733 | struct mem_cgroup *mem_cont, |
734 | unsigned long *vm_flags) | |
1da177e4 LT |
735 | { |
736 | unsigned int mapcount; | |
737 | struct address_space *mapping = page->mapping; | |
738 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
739 | struct vm_area_struct *vma; | |
740 | struct prio_tree_iter iter; | |
741 | int referenced = 0; | |
742 | ||
743 | /* | |
744 | * The caller's checks on page->mapping and !PageAnon have made | |
745 | * sure that this is a file page: the check for page->mapping | |
746 | * excludes the case just before it gets set on an anon page. | |
747 | */ | |
748 | BUG_ON(PageAnon(page)); | |
749 | ||
750 | /* | |
751 | * The page lock not only makes sure that page->mapping cannot | |
752 | * suddenly be NULLified by truncation, it makes sure that the | |
753 | * structure at mapping cannot be freed and reused yet, | |
3d48ae45 | 754 | * so we can safely take mapping->i_mmap_mutex. |
1da177e4 LT |
755 | */ |
756 | BUG_ON(!PageLocked(page)); | |
757 | ||
3d48ae45 | 758 | mutex_lock(&mapping->i_mmap_mutex); |
1da177e4 LT |
759 | |
760 | /* | |
3d48ae45 | 761 | * i_mmap_mutex does not stabilize mapcount at all, but mapcount |
1da177e4 LT |
762 | * is more likely to be accurate if we note it after spinning. |
763 | */ | |
764 | mapcount = page_mapcount(page); | |
765 | ||
766 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
1cb1729b HD |
767 | unsigned long address = vma_address(page, vma); |
768 | if (address == -EFAULT) | |
769 | continue; | |
bed7161a BS |
770 | /* |
771 | * If we are reclaiming on behalf of a cgroup, skip | |
772 | * counting on behalf of references from different | |
773 | * cgroups | |
774 | */ | |
bd845e38 | 775 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 776 | continue; |
1cb1729b | 777 | referenced += page_referenced_one(page, vma, address, |
6fe6b7e3 | 778 | &mapcount, vm_flags); |
1da177e4 LT |
779 | if (!mapcount) |
780 | break; | |
781 | } | |
782 | ||
3d48ae45 | 783 | mutex_unlock(&mapping->i_mmap_mutex); |
1da177e4 LT |
784 | return referenced; |
785 | } | |
786 | ||
787 | /** | |
788 | * page_referenced - test if the page was referenced | |
789 | * @page: the page to test | |
790 | * @is_locked: caller holds lock on the page | |
43d8eac4 | 791 | * @mem_cont: target memory controller |
6fe6b7e3 | 792 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
793 | * |
794 | * Quick test_and_clear_referenced for all mappings to a page, | |
795 | * returns the number of ptes which referenced the page. | |
796 | */ | |
6fe6b7e3 WF |
797 | int page_referenced(struct page *page, |
798 | int is_locked, | |
799 | struct mem_cgroup *mem_cont, | |
800 | unsigned long *vm_flags) | |
1da177e4 LT |
801 | { |
802 | int referenced = 0; | |
5ad64688 | 803 | int we_locked = 0; |
1da177e4 | 804 | |
6fe6b7e3 | 805 | *vm_flags = 0; |
3ca7b3c5 | 806 | if (page_mapped(page) && page_rmapping(page)) { |
5ad64688 HD |
807 | if (!is_locked && (!PageAnon(page) || PageKsm(page))) { |
808 | we_locked = trylock_page(page); | |
809 | if (!we_locked) { | |
810 | referenced++; | |
811 | goto out; | |
812 | } | |
813 | } | |
814 | if (unlikely(PageKsm(page))) | |
815 | referenced += page_referenced_ksm(page, mem_cont, | |
816 | vm_flags); | |
817 | else if (PageAnon(page)) | |
6fe6b7e3 WF |
818 | referenced += page_referenced_anon(page, mem_cont, |
819 | vm_flags); | |
5ad64688 | 820 | else if (page->mapping) |
6fe6b7e3 WF |
821 | referenced += page_referenced_file(page, mem_cont, |
822 | vm_flags); | |
5ad64688 | 823 | if (we_locked) |
1da177e4 | 824 | unlock_page(page); |
1da177e4 | 825 | } |
5ad64688 | 826 | out: |
2d42552d | 827 | if (page_test_and_clear_young(page_to_pfn(page))) |
5b7baf05 CB |
828 | referenced++; |
829 | ||
1da177e4 LT |
830 | return referenced; |
831 | } | |
832 | ||
1cb1729b HD |
833 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, |
834 | unsigned long address) | |
d08b3851 PZ |
835 | { |
836 | struct mm_struct *mm = vma->vm_mm; | |
c2fda5fe | 837 | pte_t *pte; |
d08b3851 PZ |
838 | spinlock_t *ptl; |
839 | int ret = 0; | |
840 | ||
479db0bf | 841 | pte = page_check_address(page, mm, address, &ptl, 1); |
d08b3851 PZ |
842 | if (!pte) |
843 | goto out; | |
844 | ||
c2fda5fe PZ |
845 | if (pte_dirty(*pte) || pte_write(*pte)) { |
846 | pte_t entry; | |
d08b3851 | 847 | |
c2fda5fe | 848 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 849 | entry = ptep_clear_flush_notify(vma, address, pte); |
c2fda5fe PZ |
850 | entry = pte_wrprotect(entry); |
851 | entry = pte_mkclean(entry); | |
d6e88e67 | 852 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
853 | ret = 1; |
854 | } | |
d08b3851 | 855 | |
d08b3851 PZ |
856 | pte_unmap_unlock(pte, ptl); |
857 | out: | |
858 | return ret; | |
859 | } | |
860 | ||
861 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
862 | { | |
863 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
864 | struct vm_area_struct *vma; | |
865 | struct prio_tree_iter iter; | |
866 | int ret = 0; | |
867 | ||
868 | BUG_ON(PageAnon(page)); | |
869 | ||
3d48ae45 | 870 | mutex_lock(&mapping->i_mmap_mutex); |
d08b3851 | 871 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
1cb1729b HD |
872 | if (vma->vm_flags & VM_SHARED) { |
873 | unsigned long address = vma_address(page, vma); | |
874 | if (address == -EFAULT) | |
875 | continue; | |
876 | ret += page_mkclean_one(page, vma, address); | |
877 | } | |
d08b3851 | 878 | } |
3d48ae45 | 879 | mutex_unlock(&mapping->i_mmap_mutex); |
d08b3851 PZ |
880 | return ret; |
881 | } | |
882 | ||
883 | int page_mkclean(struct page *page) | |
884 | { | |
885 | int ret = 0; | |
886 | ||
887 | BUG_ON(!PageLocked(page)); | |
888 | ||
889 | if (page_mapped(page)) { | |
890 | struct address_space *mapping = page_mapping(page); | |
ce7e9fae | 891 | if (mapping) { |
d08b3851 | 892 | ret = page_mkclean_file(mapping, page); |
2d42552d | 893 | if (page_test_and_clear_dirty(page_to_pfn(page), 1)) |
ce7e9fae | 894 | ret = 1; |
6c210482 | 895 | } |
d08b3851 PZ |
896 | } |
897 | ||
898 | return ret; | |
899 | } | |
60b59bea | 900 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 901 | |
c44b6743 RR |
902 | /** |
903 | * page_move_anon_rmap - move a page to our anon_vma | |
904 | * @page: the page to move to our anon_vma | |
905 | * @vma: the vma the page belongs to | |
906 | * @address: the user virtual address mapped | |
907 | * | |
908 | * When a page belongs exclusively to one process after a COW event, | |
909 | * that page can be moved into the anon_vma that belongs to just that | |
910 | * process, so the rmap code will not search the parent or sibling | |
911 | * processes. | |
912 | */ | |
913 | void page_move_anon_rmap(struct page *page, | |
914 | struct vm_area_struct *vma, unsigned long address) | |
915 | { | |
916 | struct anon_vma *anon_vma = vma->anon_vma; | |
917 | ||
918 | VM_BUG_ON(!PageLocked(page)); | |
919 | VM_BUG_ON(!anon_vma); | |
920 | VM_BUG_ON(page->index != linear_page_index(vma, address)); | |
921 | ||
922 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
923 | page->mapping = (struct address_space *) anon_vma; | |
924 | } | |
925 | ||
9617d95e | 926 | /** |
4e1c1975 AK |
927 | * __page_set_anon_rmap - set up new anonymous rmap |
928 | * @page: Page to add to rmap | |
929 | * @vma: VM area to add page to. | |
930 | * @address: User virtual address of the mapping | |
e8a03feb | 931 | * @exclusive: the page is exclusively owned by the current process |
9617d95e NP |
932 | */ |
933 | static void __page_set_anon_rmap(struct page *page, | |
e8a03feb | 934 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
9617d95e | 935 | { |
e8a03feb | 936 | struct anon_vma *anon_vma = vma->anon_vma; |
ea90002b | 937 | |
e8a03feb | 938 | BUG_ON(!anon_vma); |
ea90002b | 939 | |
4e1c1975 AK |
940 | if (PageAnon(page)) |
941 | return; | |
942 | ||
ea90002b | 943 | /* |
e8a03feb RR |
944 | * If the page isn't exclusively mapped into this vma, |
945 | * we must use the _oldest_ possible anon_vma for the | |
946 | * page mapping! | |
ea90002b | 947 | */ |
4e1c1975 | 948 | if (!exclusive) |
288468c3 | 949 | anon_vma = anon_vma->root; |
9617d95e | 950 | |
9617d95e NP |
951 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
952 | page->mapping = (struct address_space *) anon_vma; | |
9617d95e | 953 | page->index = linear_page_index(vma, address); |
9617d95e NP |
954 | } |
955 | ||
c97a9e10 | 956 | /** |
43d8eac4 | 957 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
c97a9e10 NP |
958 | * @page: the page to add the mapping to |
959 | * @vma: the vm area in which the mapping is added | |
960 | * @address: the user virtual address mapped | |
961 | */ | |
962 | static void __page_check_anon_rmap(struct page *page, | |
963 | struct vm_area_struct *vma, unsigned long address) | |
964 | { | |
965 | #ifdef CONFIG_DEBUG_VM | |
966 | /* | |
967 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
968 | * be set up correctly at this point. | |
969 | * | |
970 | * We have exclusion against page_add_anon_rmap because the caller | |
971 | * always holds the page locked, except if called from page_dup_rmap, | |
972 | * in which case the page is already known to be setup. | |
973 | * | |
974 | * We have exclusion against page_add_new_anon_rmap because those pages | |
975 | * are initially only visible via the pagetables, and the pte is locked | |
976 | * over the call to page_add_new_anon_rmap. | |
977 | */ | |
44ab57a0 | 978 | BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); |
c97a9e10 NP |
979 | BUG_ON(page->index != linear_page_index(vma, address)); |
980 | #endif | |
981 | } | |
982 | ||
1da177e4 LT |
983 | /** |
984 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
985 | * @page: the page to add the mapping to | |
986 | * @vma: the vm area in which the mapping is added | |
987 | * @address: the user virtual address mapped | |
988 | * | |
5ad64688 | 989 | * The caller needs to hold the pte lock, and the page must be locked in |
80e14822 HD |
990 | * the anon_vma case: to serialize mapping,index checking after setting, |
991 | * and to ensure that PageAnon is not being upgraded racily to PageKsm | |
992 | * (but PageKsm is never downgraded to PageAnon). | |
1da177e4 LT |
993 | */ |
994 | void page_add_anon_rmap(struct page *page, | |
995 | struct vm_area_struct *vma, unsigned long address) | |
ad8c2ee8 RR |
996 | { |
997 | do_page_add_anon_rmap(page, vma, address, 0); | |
998 | } | |
999 | ||
1000 | /* | |
1001 | * Special version of the above for do_swap_page, which often runs | |
1002 | * into pages that are exclusively owned by the current process. | |
1003 | * Everybody else should continue to use page_add_anon_rmap above. | |
1004 | */ | |
1005 | void do_page_add_anon_rmap(struct page *page, | |
1006 | struct vm_area_struct *vma, unsigned long address, int exclusive) | |
1da177e4 | 1007 | { |
5ad64688 | 1008 | int first = atomic_inc_and_test(&page->_mapcount); |
79134171 AA |
1009 | if (first) { |
1010 | if (!PageTransHuge(page)) | |
1011 | __inc_zone_page_state(page, NR_ANON_PAGES); | |
1012 | else | |
1013 | __inc_zone_page_state(page, | |
1014 | NR_ANON_TRANSPARENT_HUGEPAGES); | |
1015 | } | |
5ad64688 HD |
1016 | if (unlikely(PageKsm(page))) |
1017 | return; | |
1018 | ||
c97a9e10 | 1019 | VM_BUG_ON(!PageLocked(page)); |
5dbe0af4 | 1020 | /* address might be in next vma when migration races vma_adjust */ |
5ad64688 | 1021 | if (first) |
ad8c2ee8 | 1022 | __page_set_anon_rmap(page, vma, address, exclusive); |
69029cd5 | 1023 | else |
c97a9e10 | 1024 | __page_check_anon_rmap(page, vma, address); |
1da177e4 LT |
1025 | } |
1026 | ||
43d8eac4 | 1027 | /** |
9617d95e NP |
1028 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
1029 | * @page: the page to add the mapping to | |
1030 | * @vma: the vm area in which the mapping is added | |
1031 | * @address: the user virtual address mapped | |
1032 | * | |
1033 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
1034 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 1035 | * Page does not have to be locked. |
9617d95e NP |
1036 | */ |
1037 | void page_add_new_anon_rmap(struct page *page, | |
1038 | struct vm_area_struct *vma, unsigned long address) | |
1039 | { | |
b5934c53 | 1040 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
cbf84b7a HD |
1041 | SetPageSwapBacked(page); |
1042 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ | |
79134171 AA |
1043 | if (!PageTransHuge(page)) |
1044 | __inc_zone_page_state(page, NR_ANON_PAGES); | |
1045 | else | |
1046 | __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
e8a03feb | 1047 | __page_set_anon_rmap(page, vma, address, 1); |
b5934c53 | 1048 | if (page_evictable(page, vma)) |
cbf84b7a | 1049 | lru_cache_add_lru(page, LRU_ACTIVE_ANON); |
b5934c53 HD |
1050 | else |
1051 | add_page_to_unevictable_list(page); | |
9617d95e NP |
1052 | } |
1053 | ||
1da177e4 LT |
1054 | /** |
1055 | * page_add_file_rmap - add pte mapping to a file page | |
1056 | * @page: the page to add the mapping to | |
1057 | * | |
b8072f09 | 1058 | * The caller needs to hold the pte lock. |
1da177e4 LT |
1059 | */ |
1060 | void page_add_file_rmap(struct page *page) | |
1061 | { | |
d69b042f | 1062 | if (atomic_inc_and_test(&page->_mapcount)) { |
65ba55f5 | 1063 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
2a7106f2 | 1064 | mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED); |
d69b042f | 1065 | } |
1da177e4 LT |
1066 | } |
1067 | ||
1068 | /** | |
1069 | * page_remove_rmap - take down pte mapping from a page | |
1070 | * @page: page to remove mapping from | |
1071 | * | |
b8072f09 | 1072 | * The caller needs to hold the pte lock. |
1da177e4 | 1073 | */ |
edc315fd | 1074 | void page_remove_rmap(struct page *page) |
1da177e4 | 1075 | { |
b904dcfe KM |
1076 | /* page still mapped by someone else? */ |
1077 | if (!atomic_add_negative(-1, &page->_mapcount)) | |
1078 | return; | |
1079 | ||
1080 | /* | |
1081 | * Now that the last pte has gone, s390 must transfer dirty | |
1082 | * flag from storage key to struct page. We can usually skip | |
1083 | * this if the page is anon, so about to be freed; but perhaps | |
1084 | * not if it's in swapcache - there might be another pte slot | |
1085 | * containing the swap entry, but page not yet written to swap. | |
1086 | */ | |
2d42552d MS |
1087 | if ((!PageAnon(page) || PageSwapCache(page)) && |
1088 | page_test_and_clear_dirty(page_to_pfn(page), 1)) | |
b904dcfe | 1089 | set_page_dirty(page); |
0fe6e20b NH |
1090 | /* |
1091 | * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED | |
1092 | * and not charged by memcg for now. | |
1093 | */ | |
1094 | if (unlikely(PageHuge(page))) | |
1095 | return; | |
b904dcfe KM |
1096 | if (PageAnon(page)) { |
1097 | mem_cgroup_uncharge_page(page); | |
79134171 AA |
1098 | if (!PageTransHuge(page)) |
1099 | __dec_zone_page_state(page, NR_ANON_PAGES); | |
1100 | else | |
1101 | __dec_zone_page_state(page, | |
1102 | NR_ANON_TRANSPARENT_HUGEPAGES); | |
b904dcfe KM |
1103 | } else { |
1104 | __dec_zone_page_state(page, NR_FILE_MAPPED); | |
2a7106f2 | 1105 | mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED); |
b904dcfe | 1106 | } |
b904dcfe KM |
1107 | /* |
1108 | * It would be tidy to reset the PageAnon mapping here, | |
1109 | * but that might overwrite a racing page_add_anon_rmap | |
1110 | * which increments mapcount after us but sets mapping | |
1111 | * before us: so leave the reset to free_hot_cold_page, | |
1112 | * and remember that it's only reliable while mapped. | |
1113 | * Leaving it set also helps swapoff to reinstate ptes | |
1114 | * faster for those pages still in swapcache. | |
1115 | */ | |
1da177e4 LT |
1116 | } |
1117 | ||
1118 | /* | |
1119 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
1120 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. | |
1121 | */ | |
5ad64688 HD |
1122 | int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
1123 | unsigned long address, enum ttu_flags flags) | |
1da177e4 LT |
1124 | { |
1125 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 LT |
1126 | pte_t *pte; |
1127 | pte_t pteval; | |
c0718806 | 1128 | spinlock_t *ptl; |
1da177e4 LT |
1129 | int ret = SWAP_AGAIN; |
1130 | ||
479db0bf | 1131 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 | 1132 | if (!pte) |
81b4082d | 1133 | goto out; |
1da177e4 LT |
1134 | |
1135 | /* | |
1136 | * If the page is mlock()d, we cannot swap it out. | |
1137 | * If it's recently referenced (perhaps page_referenced | |
1138 | * skipped over this mm) then we should reactivate it. | |
1139 | */ | |
14fa31b8 | 1140 | if (!(flags & TTU_IGNORE_MLOCK)) { |
caed0f48 KM |
1141 | if (vma->vm_flags & VM_LOCKED) |
1142 | goto out_mlock; | |
1143 | ||
af8e3354 | 1144 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
53f79acb | 1145 | goto out_unmap; |
14fa31b8 AK |
1146 | } |
1147 | if (!(flags & TTU_IGNORE_ACCESS)) { | |
b291f000 NP |
1148 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
1149 | ret = SWAP_FAIL; | |
1150 | goto out_unmap; | |
1151 | } | |
1152 | } | |
1da177e4 | 1153 | |
1da177e4 LT |
1154 | /* Nuke the page table entry. */ |
1155 | flush_cache_page(vma, address, page_to_pfn(page)); | |
cddb8a5c | 1156 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
1157 | |
1158 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
1159 | if (pte_dirty(pteval)) | |
1160 | set_page_dirty(page); | |
1161 | ||
365e9c87 HD |
1162 | /* Update high watermark before we lower rss */ |
1163 | update_hiwater_rss(mm); | |
1164 | ||
888b9f7c AK |
1165 | if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
1166 | if (PageAnon(page)) | |
d559db08 | 1167 | dec_mm_counter(mm, MM_ANONPAGES); |
888b9f7c | 1168 | else |
d559db08 | 1169 | dec_mm_counter(mm, MM_FILEPAGES); |
888b9f7c AK |
1170 | set_pte_at(mm, address, pte, |
1171 | swp_entry_to_pte(make_hwpoison_entry(page))); | |
1172 | } else if (PageAnon(page)) { | |
4c21e2f2 | 1173 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
1174 | |
1175 | if (PageSwapCache(page)) { | |
1176 | /* | |
1177 | * Store the swap location in the pte. | |
1178 | * See handle_pte_fault() ... | |
1179 | */ | |
570a335b HD |
1180 | if (swap_duplicate(entry) < 0) { |
1181 | set_pte_at(mm, address, pte, pteval); | |
1182 | ret = SWAP_FAIL; | |
1183 | goto out_unmap; | |
1184 | } | |
0697212a CL |
1185 | if (list_empty(&mm->mmlist)) { |
1186 | spin_lock(&mmlist_lock); | |
1187 | if (list_empty(&mm->mmlist)) | |
1188 | list_add(&mm->mmlist, &init_mm.mmlist); | |
1189 | spin_unlock(&mmlist_lock); | |
1190 | } | |
d559db08 | 1191 | dec_mm_counter(mm, MM_ANONPAGES); |
b084d435 | 1192 | inc_mm_counter(mm, MM_SWAPENTS); |
64cdd548 | 1193 | } else if (PAGE_MIGRATION) { |
0697212a CL |
1194 | /* |
1195 | * Store the pfn of the page in a special migration | |
1196 | * pte. do_swap_page() will wait until the migration | |
1197 | * pte is removed and then restart fault handling. | |
1198 | */ | |
14fa31b8 | 1199 | BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION); |
0697212a | 1200 | entry = make_migration_entry(page, pte_write(pteval)); |
1da177e4 LT |
1201 | } |
1202 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
1203 | BUG_ON(pte_file(*pte)); | |
14fa31b8 | 1204 | } else if (PAGE_MIGRATION && (TTU_ACTION(flags) == TTU_MIGRATION)) { |
04e62a29 CL |
1205 | /* Establish migration entry for a file page */ |
1206 | swp_entry_t entry; | |
1207 | entry = make_migration_entry(page, pte_write(pteval)); | |
1208 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
1209 | } else | |
d559db08 | 1210 | dec_mm_counter(mm, MM_FILEPAGES); |
1da177e4 | 1211 | |
edc315fd | 1212 | page_remove_rmap(page); |
1da177e4 LT |
1213 | page_cache_release(page); |
1214 | ||
1215 | out_unmap: | |
c0718806 | 1216 | pte_unmap_unlock(pte, ptl); |
caed0f48 KM |
1217 | out: |
1218 | return ret; | |
53f79acb | 1219 | |
caed0f48 KM |
1220 | out_mlock: |
1221 | pte_unmap_unlock(pte, ptl); | |
1222 | ||
1223 | ||
1224 | /* | |
1225 | * We need mmap_sem locking, Otherwise VM_LOCKED check makes | |
1226 | * unstable result and race. Plus, We can't wait here because | |
2b575eb6 | 1227 | * we now hold anon_vma->mutex or mapping->i_mmap_mutex. |
caed0f48 KM |
1228 | * if trylock failed, the page remain in evictable lru and later |
1229 | * vmscan could retry to move the page to unevictable lru if the | |
1230 | * page is actually mlocked. | |
1231 | */ | |
1232 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
1233 | if (vma->vm_flags & VM_LOCKED) { | |
1234 | mlock_vma_page(page); | |
1235 | ret = SWAP_MLOCK; | |
53f79acb | 1236 | } |
caed0f48 | 1237 | up_read(&vma->vm_mm->mmap_sem); |
53f79acb | 1238 | } |
1da177e4 LT |
1239 | return ret; |
1240 | } | |
1241 | ||
1242 | /* | |
1243 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
1244 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
1245 | * Consequently, given a particular page and its ->index, we cannot locate the | |
1246 | * ptes which are mapping that page without an exhaustive linear search. | |
1247 | * | |
1248 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
1249 | * maps the file to which the target page belongs. The ->vm_private_data field | |
1250 | * holds the current cursor into that scan. Successive searches will circulate | |
1251 | * around the vma's virtual address space. | |
1252 | * | |
1253 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
1254 | * more scanning pressure is placed against them as well. Eventually pages | |
1255 | * will become fully unmapped and are eligible for eviction. | |
1256 | * | |
1257 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
1258 | * there there won't be many ptes located within the scan cluster. In this case | |
1259 | * maybe we could scan further - to the end of the pte page, perhaps. | |
b291f000 NP |
1260 | * |
1261 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can | |
1262 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, | |
1263 | * rather than unmapping them. If we encounter the "check_page" that vmscan is | |
1264 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. | |
1da177e4 LT |
1265 | */ |
1266 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
1267 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
1268 | ||
b291f000 NP |
1269 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
1270 | struct vm_area_struct *vma, struct page *check_page) | |
1da177e4 LT |
1271 | { |
1272 | struct mm_struct *mm = vma->vm_mm; | |
1273 | pgd_t *pgd; | |
1274 | pud_t *pud; | |
1275 | pmd_t *pmd; | |
c0718806 | 1276 | pte_t *pte; |
1da177e4 | 1277 | pte_t pteval; |
c0718806 | 1278 | spinlock_t *ptl; |
1da177e4 LT |
1279 | struct page *page; |
1280 | unsigned long address; | |
1281 | unsigned long end; | |
b291f000 NP |
1282 | int ret = SWAP_AGAIN; |
1283 | int locked_vma = 0; | |
1da177e4 | 1284 | |
1da177e4 LT |
1285 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
1286 | end = address + CLUSTER_SIZE; | |
1287 | if (address < vma->vm_start) | |
1288 | address = vma->vm_start; | |
1289 | if (end > vma->vm_end) | |
1290 | end = vma->vm_end; | |
1291 | ||
1292 | pgd = pgd_offset(mm, address); | |
1293 | if (!pgd_present(*pgd)) | |
b291f000 | 1294 | return ret; |
1da177e4 LT |
1295 | |
1296 | pud = pud_offset(pgd, address); | |
1297 | if (!pud_present(*pud)) | |
b291f000 | 1298 | return ret; |
1da177e4 LT |
1299 | |
1300 | pmd = pmd_offset(pud, address); | |
1301 | if (!pmd_present(*pmd)) | |
b291f000 NP |
1302 | return ret; |
1303 | ||
1304 | /* | |
af8e3354 | 1305 | * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, |
b291f000 NP |
1306 | * keep the sem while scanning the cluster for mlocking pages. |
1307 | */ | |
af8e3354 | 1308 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
b291f000 NP |
1309 | locked_vma = (vma->vm_flags & VM_LOCKED); |
1310 | if (!locked_vma) | |
1311 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ | |
1312 | } | |
c0718806 HD |
1313 | |
1314 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 1315 | |
365e9c87 HD |
1316 | /* Update high watermark before we lower rss */ |
1317 | update_hiwater_rss(mm); | |
1318 | ||
c0718806 | 1319 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
1320 | if (!pte_present(*pte)) |
1321 | continue; | |
6aab341e LT |
1322 | page = vm_normal_page(vma, address, *pte); |
1323 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 | 1324 | |
b291f000 NP |
1325 | if (locked_vma) { |
1326 | mlock_vma_page(page); /* no-op if already mlocked */ | |
1327 | if (page == check_page) | |
1328 | ret = SWAP_MLOCK; | |
1329 | continue; /* don't unmap */ | |
1330 | } | |
1331 | ||
cddb8a5c | 1332 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1da177e4 LT |
1333 | continue; |
1334 | ||
1335 | /* Nuke the page table entry. */ | |
eca35133 | 1336 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 1337 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
1338 | |
1339 | /* If nonlinear, store the file page offset in the pte. */ | |
1340 | if (page->index != linear_page_index(vma, address)) | |
1341 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
1342 | ||
1343 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
1344 | if (pte_dirty(pteval)) | |
1345 | set_page_dirty(page); | |
1346 | ||
edc315fd | 1347 | page_remove_rmap(page); |
1da177e4 | 1348 | page_cache_release(page); |
d559db08 | 1349 | dec_mm_counter(mm, MM_FILEPAGES); |
1da177e4 LT |
1350 | (*mapcount)--; |
1351 | } | |
c0718806 | 1352 | pte_unmap_unlock(pte - 1, ptl); |
b291f000 NP |
1353 | if (locked_vma) |
1354 | up_read(&vma->vm_mm->mmap_sem); | |
1355 | return ret; | |
1da177e4 LT |
1356 | } |
1357 | ||
71e3aac0 | 1358 | bool is_vma_temporary_stack(struct vm_area_struct *vma) |
a8bef8ff MG |
1359 | { |
1360 | int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); | |
1361 | ||
1362 | if (!maybe_stack) | |
1363 | return false; | |
1364 | ||
1365 | if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == | |
1366 | VM_STACK_INCOMPLETE_SETUP) | |
1367 | return true; | |
1368 | ||
1369 | return false; | |
1370 | } | |
1371 | ||
b291f000 NP |
1372 | /** |
1373 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based | |
1374 | * rmap method | |
1375 | * @page: the page to unmap/unlock | |
8051be5e | 1376 | * @flags: action and flags |
b291f000 NP |
1377 | * |
1378 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1379 | * contained in the anon_vma struct it points to. | |
1380 | * | |
1381 | * This function is only called from try_to_unmap/try_to_munlock for | |
1382 | * anonymous pages. | |
1383 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1384 | * where the page was found will be held for write. So, we won't recheck | |
1385 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1386 | * 'LOCKED. | |
1387 | */ | |
14fa31b8 | 1388 | static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1389 | { |
1390 | struct anon_vma *anon_vma; | |
5beb4930 | 1391 | struct anon_vma_chain *avc; |
1da177e4 | 1392 | int ret = SWAP_AGAIN; |
b291f000 | 1393 | |
1da177e4 LT |
1394 | anon_vma = page_lock_anon_vma(page); |
1395 | if (!anon_vma) | |
1396 | return ret; | |
1397 | ||
5beb4930 RR |
1398 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1399 | struct vm_area_struct *vma = avc->vma; | |
a8bef8ff MG |
1400 | unsigned long address; |
1401 | ||
1402 | /* | |
1403 | * During exec, a temporary VMA is setup and later moved. | |
1404 | * The VMA is moved under the anon_vma lock but not the | |
1405 | * page tables leading to a race where migration cannot | |
1406 | * find the migration ptes. Rather than increasing the | |
1407 | * locking requirements of exec(), migration skips | |
1408 | * temporary VMAs until after exec() completes. | |
1409 | */ | |
1410 | if (PAGE_MIGRATION && (flags & TTU_MIGRATION) && | |
1411 | is_vma_temporary_stack(vma)) | |
1412 | continue; | |
1413 | ||
1414 | address = vma_address(page, vma); | |
1cb1729b HD |
1415 | if (address == -EFAULT) |
1416 | continue; | |
1417 | ret = try_to_unmap_one(page, vma, address, flags); | |
53f79acb HD |
1418 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1419 | break; | |
1da177e4 | 1420 | } |
34bbd704 ON |
1421 | |
1422 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
1423 | return ret; |
1424 | } | |
1425 | ||
1426 | /** | |
b291f000 NP |
1427 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
1428 | * @page: the page to unmap/unlock | |
14fa31b8 | 1429 | * @flags: action and flags |
1da177e4 LT |
1430 | * |
1431 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1432 | * contained in the address_space struct it points to. | |
1433 | * | |
b291f000 NP |
1434 | * This function is only called from try_to_unmap/try_to_munlock for |
1435 | * object-based pages. | |
1436 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1437 | * where the page was found will be held for write. So, we won't recheck | |
1438 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1439 | * 'LOCKED. | |
1da177e4 | 1440 | */ |
14fa31b8 | 1441 | static int try_to_unmap_file(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1442 | { |
1443 | struct address_space *mapping = page->mapping; | |
1444 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1445 | struct vm_area_struct *vma; | |
1446 | struct prio_tree_iter iter; | |
1447 | int ret = SWAP_AGAIN; | |
1448 | unsigned long cursor; | |
1449 | unsigned long max_nl_cursor = 0; | |
1450 | unsigned long max_nl_size = 0; | |
1451 | unsigned int mapcount; | |
1452 | ||
3d48ae45 | 1453 | mutex_lock(&mapping->i_mmap_mutex); |
1da177e4 | 1454 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
1cb1729b HD |
1455 | unsigned long address = vma_address(page, vma); |
1456 | if (address == -EFAULT) | |
1457 | continue; | |
1458 | ret = try_to_unmap_one(page, vma, address, flags); | |
53f79acb HD |
1459 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1460 | goto out; | |
1da177e4 LT |
1461 | } |
1462 | ||
1463 | if (list_empty(&mapping->i_mmap_nonlinear)) | |
1464 | goto out; | |
1465 | ||
53f79acb HD |
1466 | /* |
1467 | * We don't bother to try to find the munlocked page in nonlinears. | |
1468 | * It's costly. Instead, later, page reclaim logic may call | |
1469 | * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily. | |
1470 | */ | |
1471 | if (TTU_ACTION(flags) == TTU_MUNLOCK) | |
1472 | goto out; | |
1473 | ||
1da177e4 LT |
1474 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
1475 | shared.vm_set.list) { | |
1da177e4 LT |
1476 | cursor = (unsigned long) vma->vm_private_data; |
1477 | if (cursor > max_nl_cursor) | |
1478 | max_nl_cursor = cursor; | |
1479 | cursor = vma->vm_end - vma->vm_start; | |
1480 | if (cursor > max_nl_size) | |
1481 | max_nl_size = cursor; | |
1482 | } | |
1483 | ||
b291f000 | 1484 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1da177e4 LT |
1485 | ret = SWAP_FAIL; |
1486 | goto out; | |
1487 | } | |
1488 | ||
1489 | /* | |
1490 | * We don't try to search for this page in the nonlinear vmas, | |
1491 | * and page_referenced wouldn't have found it anyway. Instead | |
1492 | * just walk the nonlinear vmas trying to age and unmap some. | |
1493 | * The mapcount of the page we came in with is irrelevant, | |
1494 | * but even so use it as a guide to how hard we should try? | |
1495 | */ | |
1496 | mapcount = page_mapcount(page); | |
1497 | if (!mapcount) | |
1498 | goto out; | |
3d48ae45 | 1499 | cond_resched(); |
1da177e4 LT |
1500 | |
1501 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
1502 | if (max_nl_cursor == 0) | |
1503 | max_nl_cursor = CLUSTER_SIZE; | |
1504 | ||
1505 | do { | |
1506 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
1507 | shared.vm_set.list) { | |
1da177e4 | 1508 | cursor = (unsigned long) vma->vm_private_data; |
839b9685 | 1509 | while ( cursor < max_nl_cursor && |
1da177e4 | 1510 | cursor < vma->vm_end - vma->vm_start) { |
53f79acb HD |
1511 | if (try_to_unmap_cluster(cursor, &mapcount, |
1512 | vma, page) == SWAP_MLOCK) | |
1513 | ret = SWAP_MLOCK; | |
1da177e4 LT |
1514 | cursor += CLUSTER_SIZE; |
1515 | vma->vm_private_data = (void *) cursor; | |
1516 | if ((int)mapcount <= 0) | |
1517 | goto out; | |
1518 | } | |
1519 | vma->vm_private_data = (void *) max_nl_cursor; | |
1520 | } | |
3d48ae45 | 1521 | cond_resched(); |
1da177e4 LT |
1522 | max_nl_cursor += CLUSTER_SIZE; |
1523 | } while (max_nl_cursor <= max_nl_size); | |
1524 | ||
1525 | /* | |
1526 | * Don't loop forever (perhaps all the remaining pages are | |
1527 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
1528 | * vmas, now forgetting on which ones it had fallen behind. | |
1529 | */ | |
101d2be7 HD |
1530 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
1531 | vma->vm_private_data = NULL; | |
1da177e4 | 1532 | out: |
3d48ae45 | 1533 | mutex_unlock(&mapping->i_mmap_mutex); |
1da177e4 LT |
1534 | return ret; |
1535 | } | |
1536 | ||
1537 | /** | |
1538 | * try_to_unmap - try to remove all page table mappings to a page | |
1539 | * @page: the page to get unmapped | |
14fa31b8 | 1540 | * @flags: action and flags |
1da177e4 LT |
1541 | * |
1542 | * Tries to remove all the page table entries which are mapping this | |
1543 | * page, used in the pageout path. Caller must hold the page lock. | |
1544 | * Return values are: | |
1545 | * | |
1546 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
1547 | * SWAP_AGAIN - we missed a mapping, try again later | |
1548 | * SWAP_FAIL - the page is unswappable | |
b291f000 | 1549 | * SWAP_MLOCK - page is mlocked. |
1da177e4 | 1550 | */ |
14fa31b8 | 1551 | int try_to_unmap(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1552 | { |
1553 | int ret; | |
1554 | ||
1da177e4 | 1555 | BUG_ON(!PageLocked(page)); |
91600e9e | 1556 | VM_BUG_ON(!PageHuge(page) && PageTransHuge(page)); |
1da177e4 | 1557 | |
5ad64688 HD |
1558 | if (unlikely(PageKsm(page))) |
1559 | ret = try_to_unmap_ksm(page, flags); | |
1560 | else if (PageAnon(page)) | |
14fa31b8 | 1561 | ret = try_to_unmap_anon(page, flags); |
1da177e4 | 1562 | else |
14fa31b8 | 1563 | ret = try_to_unmap_file(page, flags); |
b291f000 | 1564 | if (ret != SWAP_MLOCK && !page_mapped(page)) |
1da177e4 LT |
1565 | ret = SWAP_SUCCESS; |
1566 | return ret; | |
1567 | } | |
81b4082d | 1568 | |
b291f000 NP |
1569 | /** |
1570 | * try_to_munlock - try to munlock a page | |
1571 | * @page: the page to be munlocked | |
1572 | * | |
1573 | * Called from munlock code. Checks all of the VMAs mapping the page | |
1574 | * to make sure nobody else has this page mlocked. The page will be | |
1575 | * returned with PG_mlocked cleared if no other vmas have it mlocked. | |
1576 | * | |
1577 | * Return values are: | |
1578 | * | |
53f79acb | 1579 | * SWAP_AGAIN - no vma is holding page mlocked, or, |
b291f000 | 1580 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem |
5ad64688 | 1581 | * SWAP_FAIL - page cannot be located at present |
b291f000 NP |
1582 | * SWAP_MLOCK - page is now mlocked. |
1583 | */ | |
1584 | int try_to_munlock(struct page *page) | |
1585 | { | |
1586 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); | |
1587 | ||
5ad64688 HD |
1588 | if (unlikely(PageKsm(page))) |
1589 | return try_to_unmap_ksm(page, TTU_MUNLOCK); | |
1590 | else if (PageAnon(page)) | |
14fa31b8 | 1591 | return try_to_unmap_anon(page, TTU_MUNLOCK); |
b291f000 | 1592 | else |
14fa31b8 | 1593 | return try_to_unmap_file(page, TTU_MUNLOCK); |
b291f000 | 1594 | } |
e9995ef9 | 1595 | |
01d8b20d | 1596 | void __put_anon_vma(struct anon_vma *anon_vma) |
76545066 | 1597 | { |
01d8b20d | 1598 | struct anon_vma *root = anon_vma->root; |
76545066 | 1599 | |
01d8b20d PZ |
1600 | if (root != anon_vma && atomic_dec_and_test(&root->refcount)) |
1601 | anon_vma_free(root); | |
76545066 | 1602 | |
01d8b20d | 1603 | anon_vma_free(anon_vma); |
76545066 | 1604 | } |
76545066 | 1605 | |
e9995ef9 HD |
1606 | #ifdef CONFIG_MIGRATION |
1607 | /* | |
1608 | * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file(): | |
1609 | * Called by migrate.c to remove migration ptes, but might be used more later. | |
1610 | */ | |
1611 | static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, | |
1612 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1613 | { | |
1614 | struct anon_vma *anon_vma; | |
5beb4930 | 1615 | struct anon_vma_chain *avc; |
e9995ef9 HD |
1616 | int ret = SWAP_AGAIN; |
1617 | ||
1618 | /* | |
1619 | * Note: remove_migration_ptes() cannot use page_lock_anon_vma() | |
1620 | * because that depends on page_mapped(); but not all its usages | |
3f6c8272 MG |
1621 | * are holding mmap_sem. Users without mmap_sem are required to |
1622 | * take a reference count to prevent the anon_vma disappearing | |
e9995ef9 HD |
1623 | */ |
1624 | anon_vma = page_anon_vma(page); | |
1625 | if (!anon_vma) | |
1626 | return ret; | |
cba48b98 | 1627 | anon_vma_lock(anon_vma); |
5beb4930 RR |
1628 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1629 | struct vm_area_struct *vma = avc->vma; | |
e9995ef9 HD |
1630 | unsigned long address = vma_address(page, vma); |
1631 | if (address == -EFAULT) | |
1632 | continue; | |
1633 | ret = rmap_one(page, vma, address, arg); | |
1634 | if (ret != SWAP_AGAIN) | |
1635 | break; | |
1636 | } | |
cba48b98 | 1637 | anon_vma_unlock(anon_vma); |
e9995ef9 HD |
1638 | return ret; |
1639 | } | |
1640 | ||
1641 | static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, | |
1642 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1643 | { | |
1644 | struct address_space *mapping = page->mapping; | |
1645 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1646 | struct vm_area_struct *vma; | |
1647 | struct prio_tree_iter iter; | |
1648 | int ret = SWAP_AGAIN; | |
1649 | ||
1650 | if (!mapping) | |
1651 | return ret; | |
3d48ae45 | 1652 | mutex_lock(&mapping->i_mmap_mutex); |
e9995ef9 HD |
1653 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
1654 | unsigned long address = vma_address(page, vma); | |
1655 | if (address == -EFAULT) | |
1656 | continue; | |
1657 | ret = rmap_one(page, vma, address, arg); | |
1658 | if (ret != SWAP_AGAIN) | |
1659 | break; | |
1660 | } | |
1661 | /* | |
1662 | * No nonlinear handling: being always shared, nonlinear vmas | |
1663 | * never contain migration ptes. Decide what to do about this | |
1664 | * limitation to linear when we need rmap_walk() on nonlinear. | |
1665 | */ | |
3d48ae45 | 1666 | mutex_unlock(&mapping->i_mmap_mutex); |
e9995ef9 HD |
1667 | return ret; |
1668 | } | |
1669 | ||
1670 | int rmap_walk(struct page *page, int (*rmap_one)(struct page *, | |
1671 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1672 | { | |
1673 | VM_BUG_ON(!PageLocked(page)); | |
1674 | ||
1675 | if (unlikely(PageKsm(page))) | |
1676 | return rmap_walk_ksm(page, rmap_one, arg); | |
1677 | else if (PageAnon(page)) | |
1678 | return rmap_walk_anon(page, rmap_one, arg); | |
1679 | else | |
1680 | return rmap_walk_file(page, rmap_one, arg); | |
1681 | } | |
1682 | #endif /* CONFIG_MIGRATION */ | |
0fe6e20b | 1683 | |
e3390f67 | 1684 | #ifdef CONFIG_HUGETLB_PAGE |
0fe6e20b NH |
1685 | /* |
1686 | * The following three functions are for anonymous (private mapped) hugepages. | |
1687 | * Unlike common anonymous pages, anonymous hugepages have no accounting code | |
1688 | * and no lru code, because we handle hugepages differently from common pages. | |
1689 | */ | |
1690 | static void __hugepage_set_anon_rmap(struct page *page, | |
1691 | struct vm_area_struct *vma, unsigned long address, int exclusive) | |
1692 | { | |
1693 | struct anon_vma *anon_vma = vma->anon_vma; | |
433abed6 | 1694 | |
0fe6e20b | 1695 | BUG_ON(!anon_vma); |
433abed6 NH |
1696 | |
1697 | if (PageAnon(page)) | |
1698 | return; | |
1699 | if (!exclusive) | |
1700 | anon_vma = anon_vma->root; | |
1701 | ||
0fe6e20b NH |
1702 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1703 | page->mapping = (struct address_space *) anon_vma; | |
1704 | page->index = linear_page_index(vma, address); | |
1705 | } | |
1706 | ||
1707 | void hugepage_add_anon_rmap(struct page *page, | |
1708 | struct vm_area_struct *vma, unsigned long address) | |
1709 | { | |
1710 | struct anon_vma *anon_vma = vma->anon_vma; | |
1711 | int first; | |
a850ea30 NH |
1712 | |
1713 | BUG_ON(!PageLocked(page)); | |
0fe6e20b | 1714 | BUG_ON(!anon_vma); |
5dbe0af4 | 1715 | /* address might be in next vma when migration races vma_adjust */ |
0fe6e20b NH |
1716 | first = atomic_inc_and_test(&page->_mapcount); |
1717 | if (first) | |
1718 | __hugepage_set_anon_rmap(page, vma, address, 0); | |
1719 | } | |
1720 | ||
1721 | void hugepage_add_new_anon_rmap(struct page *page, | |
1722 | struct vm_area_struct *vma, unsigned long address) | |
1723 | { | |
1724 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
1725 | atomic_set(&page->_mapcount, 0); | |
1726 | __hugepage_set_anon_rmap(page, vma, address, 1); | |
1727 | } | |
e3390f67 | 1728 | #endif /* CONFIG_HUGETLB_PAGE */ |