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) | |
27 | * mapping->i_mmap_lock | |
28 | * anon_vma->lock | |
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 | |
43 | * anon_vma->lock (memory_failure, collect_procs_anon) | |
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)); |
fdd2e5f8 AB |
89 | kmem_cache_free(anon_vma_cachep, anon_vma); |
90 | } | |
1da177e4 | 91 | |
5beb4930 RR |
92 | static inline struct anon_vma_chain *anon_vma_chain_alloc(void) |
93 | { | |
94 | return kmem_cache_alloc(anon_vma_chain_cachep, GFP_KERNEL); | |
95 | } | |
96 | ||
e574b5fd | 97 | static void anon_vma_chain_free(struct anon_vma_chain *anon_vma_chain) |
5beb4930 RR |
98 | { |
99 | kmem_cache_free(anon_vma_chain_cachep, anon_vma_chain); | |
100 | } | |
101 | ||
d9d332e0 LT |
102 | /** |
103 | * anon_vma_prepare - attach an anon_vma to a memory region | |
104 | * @vma: the memory region in question | |
105 | * | |
106 | * This makes sure the memory mapping described by 'vma' has | |
107 | * an 'anon_vma' attached to it, so that we can associate the | |
108 | * anonymous pages mapped into it with that anon_vma. | |
109 | * | |
110 | * The common case will be that we already have one, but if | |
23a0790a | 111 | * not we either need to find an adjacent mapping that we |
d9d332e0 LT |
112 | * can re-use the anon_vma from (very common when the only |
113 | * reason for splitting a vma has been mprotect()), or we | |
114 | * allocate a new one. | |
115 | * | |
116 | * Anon-vma allocations are very subtle, because we may have | |
117 | * optimistically looked up an anon_vma in page_lock_anon_vma() | |
118 | * and that may actually touch the spinlock even in the newly | |
119 | * allocated vma (it depends on RCU to make sure that the | |
120 | * anon_vma isn't actually destroyed). | |
121 | * | |
122 | * As a result, we need to do proper anon_vma locking even | |
123 | * for the new allocation. At the same time, we do not want | |
124 | * to do any locking for the common case of already having | |
125 | * an anon_vma. | |
126 | * | |
127 | * This must be called with the mmap_sem held for reading. | |
128 | */ | |
1da177e4 LT |
129 | int anon_vma_prepare(struct vm_area_struct *vma) |
130 | { | |
131 | struct anon_vma *anon_vma = vma->anon_vma; | |
5beb4930 | 132 | struct anon_vma_chain *avc; |
1da177e4 LT |
133 | |
134 | might_sleep(); | |
135 | if (unlikely(!anon_vma)) { | |
136 | struct mm_struct *mm = vma->vm_mm; | |
d9d332e0 | 137 | struct anon_vma *allocated; |
1da177e4 | 138 | |
5beb4930 RR |
139 | avc = anon_vma_chain_alloc(); |
140 | if (!avc) | |
141 | goto out_enomem; | |
142 | ||
1da177e4 | 143 | anon_vma = find_mergeable_anon_vma(vma); |
d9d332e0 LT |
144 | allocated = NULL; |
145 | if (!anon_vma) { | |
1da177e4 LT |
146 | anon_vma = anon_vma_alloc(); |
147 | if (unlikely(!anon_vma)) | |
5beb4930 | 148 | goto out_enomem_free_avc; |
1da177e4 | 149 | allocated = anon_vma; |
1da177e4 LT |
150 | } |
151 | ||
cba48b98 | 152 | anon_vma_lock(anon_vma); |
1da177e4 LT |
153 | /* page_table_lock to protect against threads */ |
154 | spin_lock(&mm->page_table_lock); | |
155 | if (likely(!vma->anon_vma)) { | |
156 | vma->anon_vma = anon_vma; | |
5beb4930 RR |
157 | avc->anon_vma = anon_vma; |
158 | avc->vma = vma; | |
159 | list_add(&avc->same_vma, &vma->anon_vma_chain); | |
26ba0cb6 | 160 | list_add_tail(&avc->same_anon_vma, &anon_vma->head); |
1da177e4 | 161 | allocated = NULL; |
31f2b0eb | 162 | avc = NULL; |
1da177e4 LT |
163 | } |
164 | spin_unlock(&mm->page_table_lock); | |
cba48b98 | 165 | anon_vma_unlock(anon_vma); |
31f2b0eb ON |
166 | |
167 | if (unlikely(allocated)) | |
01d8b20d | 168 | put_anon_vma(allocated); |
31f2b0eb | 169 | if (unlikely(avc)) |
5beb4930 | 170 | anon_vma_chain_free(avc); |
1da177e4 LT |
171 | } |
172 | return 0; | |
5beb4930 RR |
173 | |
174 | out_enomem_free_avc: | |
175 | anon_vma_chain_free(avc); | |
176 | out_enomem: | |
177 | return -ENOMEM; | |
1da177e4 LT |
178 | } |
179 | ||
5beb4930 RR |
180 | static void anon_vma_chain_link(struct vm_area_struct *vma, |
181 | struct anon_vma_chain *avc, | |
182 | struct anon_vma *anon_vma) | |
1da177e4 | 183 | { |
5beb4930 RR |
184 | avc->vma = vma; |
185 | avc->anon_vma = anon_vma; | |
186 | list_add(&avc->same_vma, &vma->anon_vma_chain); | |
187 | ||
cba48b98 | 188 | anon_vma_lock(anon_vma); |
05759d38 AA |
189 | /* |
190 | * It's critical to add new vmas to the tail of the anon_vma, | |
191 | * see comment in huge_memory.c:__split_huge_page(). | |
192 | */ | |
5beb4930 | 193 | list_add_tail(&avc->same_anon_vma, &anon_vma->head); |
cba48b98 | 194 | anon_vma_unlock(anon_vma); |
1da177e4 LT |
195 | } |
196 | ||
5beb4930 RR |
197 | /* |
198 | * Attach the anon_vmas from src to dst. | |
199 | * Returns 0 on success, -ENOMEM on failure. | |
200 | */ | |
201 | int anon_vma_clone(struct vm_area_struct *dst, struct vm_area_struct *src) | |
1da177e4 | 202 | { |
5beb4930 RR |
203 | struct anon_vma_chain *avc, *pavc; |
204 | ||
646d87b4 | 205 | list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) { |
5beb4930 RR |
206 | avc = anon_vma_chain_alloc(); |
207 | if (!avc) | |
208 | goto enomem_failure; | |
209 | anon_vma_chain_link(dst, avc, pavc->anon_vma); | |
210 | } | |
211 | return 0; | |
1da177e4 | 212 | |
5beb4930 RR |
213 | enomem_failure: |
214 | unlink_anon_vmas(dst); | |
215 | return -ENOMEM; | |
1da177e4 LT |
216 | } |
217 | ||
5beb4930 RR |
218 | /* |
219 | * Attach vma to its own anon_vma, as well as to the anon_vmas that | |
220 | * the corresponding VMA in the parent process is attached to. | |
221 | * Returns 0 on success, non-zero on failure. | |
222 | */ | |
223 | int anon_vma_fork(struct vm_area_struct *vma, struct vm_area_struct *pvma) | |
1da177e4 | 224 | { |
5beb4930 RR |
225 | struct anon_vma_chain *avc; |
226 | struct anon_vma *anon_vma; | |
1da177e4 | 227 | |
5beb4930 RR |
228 | /* Don't bother if the parent process has no anon_vma here. */ |
229 | if (!pvma->anon_vma) | |
230 | return 0; | |
231 | ||
232 | /* | |
233 | * First, attach the new VMA to the parent VMA's anon_vmas, | |
234 | * so rmap can find non-COWed pages in child processes. | |
235 | */ | |
236 | if (anon_vma_clone(vma, pvma)) | |
237 | return -ENOMEM; | |
238 | ||
239 | /* Then add our own anon_vma. */ | |
240 | anon_vma = anon_vma_alloc(); | |
241 | if (!anon_vma) | |
242 | goto out_error; | |
243 | avc = anon_vma_chain_alloc(); | |
244 | if (!avc) | |
245 | goto out_error_free_anon_vma; | |
5c341ee1 RR |
246 | |
247 | /* | |
248 | * The root anon_vma's spinlock is the lock actually used when we | |
249 | * lock any of the anon_vmas in this anon_vma tree. | |
250 | */ | |
251 | anon_vma->root = pvma->anon_vma->root; | |
76545066 | 252 | /* |
01d8b20d PZ |
253 | * With refcounts, an anon_vma can stay around longer than the |
254 | * process it belongs to. The root anon_vma needs to be pinned until | |
255 | * this anon_vma is freed, because the lock lives in the root. | |
76545066 RR |
256 | */ |
257 | get_anon_vma(anon_vma->root); | |
5beb4930 RR |
258 | /* Mark this anon_vma as the one where our new (COWed) pages go. */ |
259 | vma->anon_vma = anon_vma; | |
5c341ee1 | 260 | anon_vma_chain_link(vma, avc, anon_vma); |
5beb4930 RR |
261 | |
262 | return 0; | |
263 | ||
264 | out_error_free_anon_vma: | |
01d8b20d | 265 | put_anon_vma(anon_vma); |
5beb4930 | 266 | out_error: |
4946d54c | 267 | unlink_anon_vmas(vma); |
5beb4930 | 268 | return -ENOMEM; |
1da177e4 LT |
269 | } |
270 | ||
5beb4930 | 271 | static void anon_vma_unlink(struct anon_vma_chain *anon_vma_chain) |
1da177e4 | 272 | { |
5beb4930 | 273 | struct anon_vma *anon_vma = anon_vma_chain->anon_vma; |
1da177e4 LT |
274 | int empty; |
275 | ||
5beb4930 | 276 | /* If anon_vma_fork fails, we can get an empty anon_vma_chain. */ |
1da177e4 LT |
277 | if (!anon_vma) |
278 | return; | |
279 | ||
cba48b98 | 280 | anon_vma_lock(anon_vma); |
5beb4930 | 281 | list_del(&anon_vma_chain->same_anon_vma); |
1da177e4 LT |
282 | |
283 | /* We must garbage collect the anon_vma if it's empty */ | |
01d8b20d | 284 | empty = list_empty(&anon_vma->head); |
cba48b98 | 285 | anon_vma_unlock(anon_vma); |
1da177e4 | 286 | |
01d8b20d PZ |
287 | if (empty) |
288 | put_anon_vma(anon_vma); | |
1da177e4 LT |
289 | } |
290 | ||
5beb4930 RR |
291 | void unlink_anon_vmas(struct vm_area_struct *vma) |
292 | { | |
293 | struct anon_vma_chain *avc, *next; | |
294 | ||
5c341ee1 RR |
295 | /* |
296 | * Unlink each anon_vma chained to the VMA. This list is ordered | |
297 | * from newest to oldest, ensuring the root anon_vma gets freed last. | |
298 | */ | |
5beb4930 RR |
299 | list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { |
300 | anon_vma_unlink(avc); | |
301 | list_del(&avc->same_vma); | |
302 | anon_vma_chain_free(avc); | |
303 | } | |
304 | } | |
305 | ||
51cc5068 | 306 | static void anon_vma_ctor(void *data) |
1da177e4 | 307 | { |
a35afb83 | 308 | struct anon_vma *anon_vma = data; |
1da177e4 | 309 | |
a35afb83 | 310 | spin_lock_init(&anon_vma->lock); |
83813267 | 311 | atomic_set(&anon_vma->refcount, 0); |
a35afb83 | 312 | INIT_LIST_HEAD(&anon_vma->head); |
1da177e4 LT |
313 | } |
314 | ||
315 | void __init anon_vma_init(void) | |
316 | { | |
317 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 318 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
5beb4930 | 319 | anon_vma_chain_cachep = KMEM_CACHE(anon_vma_chain, SLAB_PANIC); |
1da177e4 LT |
320 | } |
321 | ||
322 | /* | |
323 | * Getting a lock on a stable anon_vma from a page off the LRU is | |
324 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. | |
325 | */ | |
ea4525b6 | 326 | struct anon_vma *__page_lock_anon_vma(struct page *page) |
1da177e4 | 327 | { |
f1819427 | 328 | struct anon_vma *anon_vma, *root_anon_vma; |
1da177e4 LT |
329 | unsigned long anon_mapping; |
330 | ||
331 | rcu_read_lock(); | |
80e14822 | 332 | anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); |
3ca7b3c5 | 333 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
1da177e4 LT |
334 | goto out; |
335 | if (!page_mapped(page)) | |
336 | goto out; | |
337 | ||
338 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
f1819427 HD |
339 | root_anon_vma = ACCESS_ONCE(anon_vma->root); |
340 | spin_lock(&root_anon_vma->lock); | |
341 | ||
342 | /* | |
343 | * If this page is still mapped, then its anon_vma cannot have been | |
344 | * freed. But if it has been unmapped, we have no security against | |
345 | * the anon_vma structure being freed and reused (for another anon_vma: | |
346 | * SLAB_DESTROY_BY_RCU guarantees that - so the spin_lock above cannot | |
347 | * corrupt): with anon_vma_prepare() or anon_vma_fork() redirecting | |
348 | * anon_vma->root before page_unlock_anon_vma() is called to unlock. | |
349 | */ | |
350 | if (page_mapped(page)) | |
351 | return anon_vma; | |
352 | ||
353 | spin_unlock(&root_anon_vma->lock); | |
1da177e4 LT |
354 | out: |
355 | rcu_read_unlock(); | |
34bbd704 ON |
356 | return NULL; |
357 | } | |
358 | ||
10be22df | 359 | void page_unlock_anon_vma(struct anon_vma *anon_vma) |
ea4525b6 NK |
360 | __releases(&anon_vma->root->lock) |
361 | __releases(RCU) | |
34bbd704 | 362 | { |
cba48b98 | 363 | anon_vma_unlock(anon_vma); |
34bbd704 | 364 | rcu_read_unlock(); |
1da177e4 LT |
365 | } |
366 | ||
367 | /* | |
3ad33b24 LS |
368 | * At what user virtual address is page expected in @vma? |
369 | * Returns virtual address or -EFAULT if page's index/offset is not | |
370 | * within the range mapped the @vma. | |
1da177e4 | 371 | */ |
71e3aac0 | 372 | inline unsigned long |
1da177e4 LT |
373 | vma_address(struct page *page, struct vm_area_struct *vma) |
374 | { | |
375 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
376 | unsigned long address; | |
377 | ||
0fe6e20b NH |
378 | if (unlikely(is_vm_hugetlb_page(vma))) |
379 | pgoff = page->index << huge_page_order(page_hstate(page)); | |
1da177e4 LT |
380 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
381 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { | |
3ad33b24 | 382 | /* page should be within @vma mapping range */ |
1da177e4 LT |
383 | return -EFAULT; |
384 | } | |
385 | return address; | |
386 | } | |
387 | ||
388 | /* | |
bf89c8c8 | 389 | * At what user virtual address is page expected in vma? |
ab941e0f | 390 | * Caller should check the page is actually part of the vma. |
1da177e4 LT |
391 | */ |
392 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
393 | { | |
21d0d443 | 394 | if (PageAnon(page)) { |
4829b906 HD |
395 | struct anon_vma *page__anon_vma = page_anon_vma(page); |
396 | /* | |
397 | * Note: swapoff's unuse_vma() is more efficient with this | |
398 | * check, and needs it to match anon_vma when KSM is active. | |
399 | */ | |
400 | if (!vma->anon_vma || !page__anon_vma || | |
401 | vma->anon_vma->root != page__anon_vma->root) | |
21d0d443 AA |
402 | return -EFAULT; |
403 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
404 | if (!vma->vm_file || |
405 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
406 | return -EFAULT; |
407 | } else | |
408 | return -EFAULT; | |
409 | return vma_address(page, vma); | |
410 | } | |
411 | ||
81b4082d ND |
412 | /* |
413 | * Check that @page is mapped at @address into @mm. | |
414 | * | |
479db0bf NP |
415 | * If @sync is false, page_check_address may perform a racy check to avoid |
416 | * the page table lock when the pte is not present (helpful when reclaiming | |
417 | * highly shared pages). | |
418 | * | |
b8072f09 | 419 | * On success returns with pte mapped and locked. |
81b4082d | 420 | */ |
e9a81a82 | 421 | pte_t *__page_check_address(struct page *page, struct mm_struct *mm, |
479db0bf | 422 | unsigned long address, spinlock_t **ptlp, int sync) |
81b4082d ND |
423 | { |
424 | pgd_t *pgd; | |
425 | pud_t *pud; | |
426 | pmd_t *pmd; | |
427 | pte_t *pte; | |
c0718806 | 428 | spinlock_t *ptl; |
81b4082d | 429 | |
0fe6e20b NH |
430 | if (unlikely(PageHuge(page))) { |
431 | pte = huge_pte_offset(mm, address); | |
432 | ptl = &mm->page_table_lock; | |
433 | goto check; | |
434 | } | |
435 | ||
81b4082d | 436 | pgd = pgd_offset(mm, address); |
c0718806 HD |
437 | if (!pgd_present(*pgd)) |
438 | return NULL; | |
439 | ||
440 | pud = pud_offset(pgd, address); | |
441 | if (!pud_present(*pud)) | |
442 | return NULL; | |
443 | ||
444 | pmd = pmd_offset(pud, address); | |
445 | if (!pmd_present(*pmd)) | |
446 | return NULL; | |
71e3aac0 AA |
447 | if (pmd_trans_huge(*pmd)) |
448 | return NULL; | |
c0718806 HD |
449 | |
450 | pte = pte_offset_map(pmd, address); | |
451 | /* Make a quick check before getting the lock */ | |
479db0bf | 452 | if (!sync && !pte_present(*pte)) { |
c0718806 HD |
453 | pte_unmap(pte); |
454 | return NULL; | |
455 | } | |
456 | ||
4c21e2f2 | 457 | ptl = pte_lockptr(mm, pmd); |
0fe6e20b | 458 | check: |
c0718806 HD |
459 | spin_lock(ptl); |
460 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
461 | *ptlp = ptl; | |
462 | return pte; | |
81b4082d | 463 | } |
c0718806 HD |
464 | pte_unmap_unlock(pte, ptl); |
465 | return NULL; | |
81b4082d ND |
466 | } |
467 | ||
b291f000 NP |
468 | /** |
469 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
470 | * @page: the page to test | |
471 | * @vma: the VMA to test | |
472 | * | |
473 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
474 | * if the page is not mapped into the page tables of this VMA. Only | |
475 | * valid for normal file or anonymous VMAs. | |
476 | */ | |
6a46079c | 477 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) |
b291f000 NP |
478 | { |
479 | unsigned long address; | |
480 | pte_t *pte; | |
481 | spinlock_t *ptl; | |
482 | ||
483 | address = vma_address(page, vma); | |
484 | if (address == -EFAULT) /* out of vma range */ | |
485 | return 0; | |
486 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); | |
487 | if (!pte) /* the page is not in this mm */ | |
488 | return 0; | |
489 | pte_unmap_unlock(pte, ptl); | |
490 | ||
491 | return 1; | |
492 | } | |
493 | ||
1da177e4 LT |
494 | /* |
495 | * Subfunctions of page_referenced: page_referenced_one called | |
496 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
497 | */ | |
5ad64688 HD |
498 | int page_referenced_one(struct page *page, struct vm_area_struct *vma, |
499 | unsigned long address, unsigned int *mapcount, | |
500 | unsigned long *vm_flags) | |
1da177e4 LT |
501 | { |
502 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 LT |
503 | int referenced = 0; |
504 | ||
71e3aac0 AA |
505 | if (unlikely(PageTransHuge(page))) { |
506 | pmd_t *pmd; | |
507 | ||
508 | spin_lock(&mm->page_table_lock); | |
2da28bfd AA |
509 | /* |
510 | * rmap might return false positives; we must filter | |
511 | * these out using page_check_address_pmd(). | |
512 | */ | |
71e3aac0 AA |
513 | pmd = page_check_address_pmd(page, mm, address, |
514 | PAGE_CHECK_ADDRESS_PMD_FLAG); | |
2da28bfd AA |
515 | if (!pmd) { |
516 | spin_unlock(&mm->page_table_lock); | |
517 | goto out; | |
518 | } | |
519 | ||
520 | if (vma->vm_flags & VM_LOCKED) { | |
521 | spin_unlock(&mm->page_table_lock); | |
522 | *mapcount = 0; /* break early from loop */ | |
523 | *vm_flags |= VM_LOCKED; | |
524 | goto out; | |
525 | } | |
526 | ||
527 | /* go ahead even if the pmd is pmd_trans_splitting() */ | |
528 | if (pmdp_clear_flush_young_notify(vma, address, pmd)) | |
71e3aac0 AA |
529 | referenced++; |
530 | spin_unlock(&mm->page_table_lock); | |
531 | } else { | |
532 | pte_t *pte; | |
533 | spinlock_t *ptl; | |
534 | ||
2da28bfd AA |
535 | /* |
536 | * rmap might return false positives; we must filter | |
537 | * these out using page_check_address(). | |
538 | */ | |
71e3aac0 AA |
539 | pte = page_check_address(page, mm, address, &ptl, 0); |
540 | if (!pte) | |
541 | goto out; | |
542 | ||
2da28bfd AA |
543 | if (vma->vm_flags & VM_LOCKED) { |
544 | pte_unmap_unlock(pte, ptl); | |
545 | *mapcount = 0; /* break early from loop */ | |
546 | *vm_flags |= VM_LOCKED; | |
547 | goto out; | |
548 | } | |
549 | ||
71e3aac0 AA |
550 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
551 | /* | |
552 | * Don't treat a reference through a sequentially read | |
553 | * mapping as such. If the page has been used in | |
554 | * another mapping, we will catch it; if this other | |
555 | * mapping is already gone, the unmap path will have | |
556 | * set PG_referenced or activated the page. | |
557 | */ | |
558 | if (likely(!VM_SequentialReadHint(vma))) | |
559 | referenced++; | |
560 | } | |
561 | pte_unmap_unlock(pte, ptl); | |
562 | } | |
563 | ||
2da28bfd AA |
564 | /* Pretend the page is referenced if the task has the |
565 | swap token and is in the middle of a page fault. */ | |
566 | if (mm != current->mm && has_swap_token(mm) && | |
567 | rwsem_is_locked(&mm->mmap_sem)) | |
568 | referenced++; | |
569 | ||
c0718806 | 570 | (*mapcount)--; |
273f047e | 571 | |
6fe6b7e3 WF |
572 | if (referenced) |
573 | *vm_flags |= vma->vm_flags; | |
273f047e | 574 | out: |
1da177e4 LT |
575 | return referenced; |
576 | } | |
577 | ||
bed7161a | 578 | static int page_referenced_anon(struct page *page, |
6fe6b7e3 WF |
579 | struct mem_cgroup *mem_cont, |
580 | unsigned long *vm_flags) | |
1da177e4 LT |
581 | { |
582 | unsigned int mapcount; | |
583 | struct anon_vma *anon_vma; | |
5beb4930 | 584 | struct anon_vma_chain *avc; |
1da177e4 LT |
585 | int referenced = 0; |
586 | ||
587 | anon_vma = page_lock_anon_vma(page); | |
588 | if (!anon_vma) | |
589 | return referenced; | |
590 | ||
591 | mapcount = page_mapcount(page); | |
5beb4930 RR |
592 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
593 | struct vm_area_struct *vma = avc->vma; | |
1cb1729b HD |
594 | unsigned long address = vma_address(page, vma); |
595 | if (address == -EFAULT) | |
596 | continue; | |
bed7161a BS |
597 | /* |
598 | * If we are reclaiming on behalf of a cgroup, skip | |
599 | * counting on behalf of references from different | |
600 | * cgroups | |
601 | */ | |
bd845e38 | 602 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 603 | continue; |
1cb1729b | 604 | referenced += page_referenced_one(page, vma, address, |
6fe6b7e3 | 605 | &mapcount, vm_flags); |
1da177e4 LT |
606 | if (!mapcount) |
607 | break; | |
608 | } | |
34bbd704 ON |
609 | |
610 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
611 | return referenced; |
612 | } | |
613 | ||
614 | /** | |
615 | * page_referenced_file - referenced check for object-based rmap | |
616 | * @page: the page we're checking references on. | |
43d8eac4 | 617 | * @mem_cont: target memory controller |
6fe6b7e3 | 618 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
619 | * |
620 | * For an object-based mapped page, find all the places it is mapped and | |
621 | * check/clear the referenced flag. This is done by following the page->mapping | |
622 | * pointer, then walking the chain of vmas it holds. It returns the number | |
623 | * of references it found. | |
624 | * | |
625 | * This function is only called from page_referenced for object-based pages. | |
626 | */ | |
bed7161a | 627 | static int page_referenced_file(struct page *page, |
6fe6b7e3 WF |
628 | struct mem_cgroup *mem_cont, |
629 | unsigned long *vm_flags) | |
1da177e4 LT |
630 | { |
631 | unsigned int mapcount; | |
632 | struct address_space *mapping = page->mapping; | |
633 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
634 | struct vm_area_struct *vma; | |
635 | struct prio_tree_iter iter; | |
636 | int referenced = 0; | |
637 | ||
638 | /* | |
639 | * The caller's checks on page->mapping and !PageAnon have made | |
640 | * sure that this is a file page: the check for page->mapping | |
641 | * excludes the case just before it gets set on an anon page. | |
642 | */ | |
643 | BUG_ON(PageAnon(page)); | |
644 | ||
645 | /* | |
646 | * The page lock not only makes sure that page->mapping cannot | |
647 | * suddenly be NULLified by truncation, it makes sure that the | |
648 | * structure at mapping cannot be freed and reused yet, | |
649 | * so we can safely take mapping->i_mmap_lock. | |
650 | */ | |
651 | BUG_ON(!PageLocked(page)); | |
652 | ||
653 | spin_lock(&mapping->i_mmap_lock); | |
654 | ||
655 | /* | |
656 | * i_mmap_lock does not stabilize mapcount at all, but mapcount | |
657 | * is more likely to be accurate if we note it after spinning. | |
658 | */ | |
659 | mapcount = page_mapcount(page); | |
660 | ||
661 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
1cb1729b HD |
662 | unsigned long address = vma_address(page, vma); |
663 | if (address == -EFAULT) | |
664 | continue; | |
bed7161a BS |
665 | /* |
666 | * If we are reclaiming on behalf of a cgroup, skip | |
667 | * counting on behalf of references from different | |
668 | * cgroups | |
669 | */ | |
bd845e38 | 670 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 671 | continue; |
1cb1729b | 672 | referenced += page_referenced_one(page, vma, address, |
6fe6b7e3 | 673 | &mapcount, vm_flags); |
1da177e4 LT |
674 | if (!mapcount) |
675 | break; | |
676 | } | |
677 | ||
678 | spin_unlock(&mapping->i_mmap_lock); | |
679 | return referenced; | |
680 | } | |
681 | ||
682 | /** | |
683 | * page_referenced - test if the page was referenced | |
684 | * @page: the page to test | |
685 | * @is_locked: caller holds lock on the page | |
43d8eac4 | 686 | * @mem_cont: target memory controller |
6fe6b7e3 | 687 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
688 | * |
689 | * Quick test_and_clear_referenced for all mappings to a page, | |
690 | * returns the number of ptes which referenced the page. | |
691 | */ | |
6fe6b7e3 WF |
692 | int page_referenced(struct page *page, |
693 | int is_locked, | |
694 | struct mem_cgroup *mem_cont, | |
695 | unsigned long *vm_flags) | |
1da177e4 LT |
696 | { |
697 | int referenced = 0; | |
5ad64688 | 698 | int we_locked = 0; |
1da177e4 | 699 | |
6fe6b7e3 | 700 | *vm_flags = 0; |
3ca7b3c5 | 701 | if (page_mapped(page) && page_rmapping(page)) { |
5ad64688 HD |
702 | if (!is_locked && (!PageAnon(page) || PageKsm(page))) { |
703 | we_locked = trylock_page(page); | |
704 | if (!we_locked) { | |
705 | referenced++; | |
706 | goto out; | |
707 | } | |
708 | } | |
709 | if (unlikely(PageKsm(page))) | |
710 | referenced += page_referenced_ksm(page, mem_cont, | |
711 | vm_flags); | |
712 | else if (PageAnon(page)) | |
6fe6b7e3 WF |
713 | referenced += page_referenced_anon(page, mem_cont, |
714 | vm_flags); | |
5ad64688 | 715 | else if (page->mapping) |
6fe6b7e3 WF |
716 | referenced += page_referenced_file(page, mem_cont, |
717 | vm_flags); | |
5ad64688 | 718 | if (we_locked) |
1da177e4 | 719 | unlock_page(page); |
1da177e4 | 720 | } |
5ad64688 | 721 | out: |
5b7baf05 CB |
722 | if (page_test_and_clear_young(page)) |
723 | referenced++; | |
724 | ||
1da177e4 LT |
725 | return referenced; |
726 | } | |
727 | ||
1cb1729b HD |
728 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, |
729 | unsigned long address) | |
d08b3851 PZ |
730 | { |
731 | struct mm_struct *mm = vma->vm_mm; | |
c2fda5fe | 732 | pte_t *pte; |
d08b3851 PZ |
733 | spinlock_t *ptl; |
734 | int ret = 0; | |
735 | ||
479db0bf | 736 | pte = page_check_address(page, mm, address, &ptl, 1); |
d08b3851 PZ |
737 | if (!pte) |
738 | goto out; | |
739 | ||
c2fda5fe PZ |
740 | if (pte_dirty(*pte) || pte_write(*pte)) { |
741 | pte_t entry; | |
d08b3851 | 742 | |
c2fda5fe | 743 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 744 | entry = ptep_clear_flush_notify(vma, address, pte); |
c2fda5fe PZ |
745 | entry = pte_wrprotect(entry); |
746 | entry = pte_mkclean(entry); | |
d6e88e67 | 747 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
748 | ret = 1; |
749 | } | |
d08b3851 | 750 | |
d08b3851 PZ |
751 | pte_unmap_unlock(pte, ptl); |
752 | out: | |
753 | return ret; | |
754 | } | |
755 | ||
756 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
757 | { | |
758 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
759 | struct vm_area_struct *vma; | |
760 | struct prio_tree_iter iter; | |
761 | int ret = 0; | |
762 | ||
763 | BUG_ON(PageAnon(page)); | |
764 | ||
765 | spin_lock(&mapping->i_mmap_lock); | |
766 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
1cb1729b HD |
767 | if (vma->vm_flags & VM_SHARED) { |
768 | unsigned long address = vma_address(page, vma); | |
769 | if (address == -EFAULT) | |
770 | continue; | |
771 | ret += page_mkclean_one(page, vma, address); | |
772 | } | |
d08b3851 PZ |
773 | } |
774 | spin_unlock(&mapping->i_mmap_lock); | |
775 | return ret; | |
776 | } | |
777 | ||
778 | int page_mkclean(struct page *page) | |
779 | { | |
780 | int ret = 0; | |
781 | ||
782 | BUG_ON(!PageLocked(page)); | |
783 | ||
784 | if (page_mapped(page)) { | |
785 | struct address_space *mapping = page_mapping(page); | |
ce7e9fae | 786 | if (mapping) { |
d08b3851 | 787 | ret = page_mkclean_file(mapping, page); |
ce7e9fae | 788 | if (page_test_dirty(page)) { |
e2b8d7af | 789 | page_clear_dirty(page, 1); |
ce7e9fae CB |
790 | ret = 1; |
791 | } | |
6c210482 | 792 | } |
d08b3851 PZ |
793 | } |
794 | ||
795 | return ret; | |
796 | } | |
60b59bea | 797 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 798 | |
c44b6743 RR |
799 | /** |
800 | * page_move_anon_rmap - move a page to our anon_vma | |
801 | * @page: the page to move to our anon_vma | |
802 | * @vma: the vma the page belongs to | |
803 | * @address: the user virtual address mapped | |
804 | * | |
805 | * When a page belongs exclusively to one process after a COW event, | |
806 | * that page can be moved into the anon_vma that belongs to just that | |
807 | * process, so the rmap code will not search the parent or sibling | |
808 | * processes. | |
809 | */ | |
810 | void page_move_anon_rmap(struct page *page, | |
811 | struct vm_area_struct *vma, unsigned long address) | |
812 | { | |
813 | struct anon_vma *anon_vma = vma->anon_vma; | |
814 | ||
815 | VM_BUG_ON(!PageLocked(page)); | |
816 | VM_BUG_ON(!anon_vma); | |
817 | VM_BUG_ON(page->index != linear_page_index(vma, address)); | |
818 | ||
819 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
820 | page->mapping = (struct address_space *) anon_vma; | |
821 | } | |
822 | ||
9617d95e | 823 | /** |
4e1c1975 AK |
824 | * __page_set_anon_rmap - set up new anonymous rmap |
825 | * @page: Page to add to rmap | |
826 | * @vma: VM area to add page to. | |
827 | * @address: User virtual address of the mapping | |
e8a03feb | 828 | * @exclusive: the page is exclusively owned by the current process |
9617d95e NP |
829 | */ |
830 | static void __page_set_anon_rmap(struct page *page, | |
e8a03feb | 831 | struct vm_area_struct *vma, unsigned long address, int exclusive) |
9617d95e | 832 | { |
e8a03feb | 833 | struct anon_vma *anon_vma = vma->anon_vma; |
ea90002b | 834 | |
e8a03feb | 835 | BUG_ON(!anon_vma); |
ea90002b | 836 | |
4e1c1975 AK |
837 | if (PageAnon(page)) |
838 | return; | |
839 | ||
ea90002b | 840 | /* |
e8a03feb RR |
841 | * If the page isn't exclusively mapped into this vma, |
842 | * we must use the _oldest_ possible anon_vma for the | |
843 | * page mapping! | |
ea90002b | 844 | */ |
4e1c1975 | 845 | if (!exclusive) |
288468c3 | 846 | anon_vma = anon_vma->root; |
9617d95e | 847 | |
9617d95e NP |
848 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
849 | page->mapping = (struct address_space *) anon_vma; | |
9617d95e | 850 | page->index = linear_page_index(vma, address); |
9617d95e NP |
851 | } |
852 | ||
c97a9e10 | 853 | /** |
43d8eac4 | 854 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
c97a9e10 NP |
855 | * @page: the page to add the mapping to |
856 | * @vma: the vm area in which the mapping is added | |
857 | * @address: the user virtual address mapped | |
858 | */ | |
859 | static void __page_check_anon_rmap(struct page *page, | |
860 | struct vm_area_struct *vma, unsigned long address) | |
861 | { | |
862 | #ifdef CONFIG_DEBUG_VM | |
863 | /* | |
864 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
865 | * be set up correctly at this point. | |
866 | * | |
867 | * We have exclusion against page_add_anon_rmap because the caller | |
868 | * always holds the page locked, except if called from page_dup_rmap, | |
869 | * in which case the page is already known to be setup. | |
870 | * | |
871 | * We have exclusion against page_add_new_anon_rmap because those pages | |
872 | * are initially only visible via the pagetables, and the pte is locked | |
873 | * over the call to page_add_new_anon_rmap. | |
874 | */ | |
44ab57a0 | 875 | BUG_ON(page_anon_vma(page)->root != vma->anon_vma->root); |
c97a9e10 NP |
876 | BUG_ON(page->index != linear_page_index(vma, address)); |
877 | #endif | |
878 | } | |
879 | ||
1da177e4 LT |
880 | /** |
881 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
882 | * @page: the page to add the mapping to | |
883 | * @vma: the vm area in which the mapping is added | |
884 | * @address: the user virtual address mapped | |
885 | * | |
5ad64688 | 886 | * The caller needs to hold the pte lock, and the page must be locked in |
80e14822 HD |
887 | * the anon_vma case: to serialize mapping,index checking after setting, |
888 | * and to ensure that PageAnon is not being upgraded racily to PageKsm | |
889 | * (but PageKsm is never downgraded to PageAnon). | |
1da177e4 LT |
890 | */ |
891 | void page_add_anon_rmap(struct page *page, | |
892 | struct vm_area_struct *vma, unsigned long address) | |
ad8c2ee8 RR |
893 | { |
894 | do_page_add_anon_rmap(page, vma, address, 0); | |
895 | } | |
896 | ||
897 | /* | |
898 | * Special version of the above for do_swap_page, which often runs | |
899 | * into pages that are exclusively owned by the current process. | |
900 | * Everybody else should continue to use page_add_anon_rmap above. | |
901 | */ | |
902 | void do_page_add_anon_rmap(struct page *page, | |
903 | struct vm_area_struct *vma, unsigned long address, int exclusive) | |
1da177e4 | 904 | { |
5ad64688 | 905 | int first = atomic_inc_and_test(&page->_mapcount); |
79134171 AA |
906 | if (first) { |
907 | if (!PageTransHuge(page)) | |
908 | __inc_zone_page_state(page, NR_ANON_PAGES); | |
909 | else | |
910 | __inc_zone_page_state(page, | |
911 | NR_ANON_TRANSPARENT_HUGEPAGES); | |
912 | } | |
5ad64688 HD |
913 | if (unlikely(PageKsm(page))) |
914 | return; | |
915 | ||
c97a9e10 NP |
916 | VM_BUG_ON(!PageLocked(page)); |
917 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
5ad64688 | 918 | if (first) |
ad8c2ee8 | 919 | __page_set_anon_rmap(page, vma, address, exclusive); |
69029cd5 | 920 | else |
c97a9e10 | 921 | __page_check_anon_rmap(page, vma, address); |
1da177e4 LT |
922 | } |
923 | ||
43d8eac4 | 924 | /** |
9617d95e NP |
925 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
926 | * @page: the page to add the mapping to | |
927 | * @vma: the vm area in which the mapping is added | |
928 | * @address: the user virtual address mapped | |
929 | * | |
930 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
931 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 932 | * Page does not have to be locked. |
9617d95e NP |
933 | */ |
934 | void page_add_new_anon_rmap(struct page *page, | |
935 | struct vm_area_struct *vma, unsigned long address) | |
936 | { | |
b5934c53 | 937 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
cbf84b7a HD |
938 | SetPageSwapBacked(page); |
939 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ | |
79134171 AA |
940 | if (!PageTransHuge(page)) |
941 | __inc_zone_page_state(page, NR_ANON_PAGES); | |
942 | else | |
943 | __inc_zone_page_state(page, NR_ANON_TRANSPARENT_HUGEPAGES); | |
e8a03feb | 944 | __page_set_anon_rmap(page, vma, address, 1); |
b5934c53 | 945 | if (page_evictable(page, vma)) |
cbf84b7a | 946 | lru_cache_add_lru(page, LRU_ACTIVE_ANON); |
b5934c53 HD |
947 | else |
948 | add_page_to_unevictable_list(page); | |
9617d95e NP |
949 | } |
950 | ||
1da177e4 LT |
951 | /** |
952 | * page_add_file_rmap - add pte mapping to a file page | |
953 | * @page: the page to add the mapping to | |
954 | * | |
b8072f09 | 955 | * The caller needs to hold the pte lock. |
1da177e4 LT |
956 | */ |
957 | void page_add_file_rmap(struct page *page) | |
958 | { | |
d69b042f | 959 | if (atomic_inc_and_test(&page->_mapcount)) { |
65ba55f5 | 960 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
2a7106f2 | 961 | mem_cgroup_inc_page_stat(page, MEMCG_NR_FILE_MAPPED); |
d69b042f | 962 | } |
1da177e4 LT |
963 | } |
964 | ||
965 | /** | |
966 | * page_remove_rmap - take down pte mapping from a page | |
967 | * @page: page to remove mapping from | |
968 | * | |
b8072f09 | 969 | * The caller needs to hold the pte lock. |
1da177e4 | 970 | */ |
edc315fd | 971 | void page_remove_rmap(struct page *page) |
1da177e4 | 972 | { |
b904dcfe KM |
973 | /* page still mapped by someone else? */ |
974 | if (!atomic_add_negative(-1, &page->_mapcount)) | |
975 | return; | |
976 | ||
977 | /* | |
978 | * Now that the last pte has gone, s390 must transfer dirty | |
979 | * flag from storage key to struct page. We can usually skip | |
980 | * this if the page is anon, so about to be freed; but perhaps | |
981 | * not if it's in swapcache - there might be another pte slot | |
982 | * containing the swap entry, but page not yet written to swap. | |
983 | */ | |
984 | if ((!PageAnon(page) || PageSwapCache(page)) && page_test_dirty(page)) { | |
e2b8d7af | 985 | page_clear_dirty(page, 1); |
b904dcfe | 986 | set_page_dirty(page); |
1da177e4 | 987 | } |
0fe6e20b NH |
988 | /* |
989 | * Hugepages are not counted in NR_ANON_PAGES nor NR_FILE_MAPPED | |
990 | * and not charged by memcg for now. | |
991 | */ | |
992 | if (unlikely(PageHuge(page))) | |
993 | return; | |
b904dcfe KM |
994 | if (PageAnon(page)) { |
995 | mem_cgroup_uncharge_page(page); | |
79134171 AA |
996 | if (!PageTransHuge(page)) |
997 | __dec_zone_page_state(page, NR_ANON_PAGES); | |
998 | else | |
999 | __dec_zone_page_state(page, | |
1000 | NR_ANON_TRANSPARENT_HUGEPAGES); | |
b904dcfe KM |
1001 | } else { |
1002 | __dec_zone_page_state(page, NR_FILE_MAPPED); | |
2a7106f2 | 1003 | mem_cgroup_dec_page_stat(page, MEMCG_NR_FILE_MAPPED); |
b904dcfe | 1004 | } |
b904dcfe KM |
1005 | /* |
1006 | * It would be tidy to reset the PageAnon mapping here, | |
1007 | * but that might overwrite a racing page_add_anon_rmap | |
1008 | * which increments mapcount after us but sets mapping | |
1009 | * before us: so leave the reset to free_hot_cold_page, | |
1010 | * and remember that it's only reliable while mapped. | |
1011 | * Leaving it set also helps swapoff to reinstate ptes | |
1012 | * faster for those pages still in swapcache. | |
1013 | */ | |
1da177e4 LT |
1014 | } |
1015 | ||
1016 | /* | |
1017 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
1018 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. | |
1019 | */ | |
5ad64688 HD |
1020 | int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
1021 | unsigned long address, enum ttu_flags flags) | |
1da177e4 LT |
1022 | { |
1023 | struct mm_struct *mm = vma->vm_mm; | |
1da177e4 LT |
1024 | pte_t *pte; |
1025 | pte_t pteval; | |
c0718806 | 1026 | spinlock_t *ptl; |
1da177e4 LT |
1027 | int ret = SWAP_AGAIN; |
1028 | ||
479db0bf | 1029 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 | 1030 | if (!pte) |
81b4082d | 1031 | goto out; |
1da177e4 LT |
1032 | |
1033 | /* | |
1034 | * If the page is mlock()d, we cannot swap it out. | |
1035 | * If it's recently referenced (perhaps page_referenced | |
1036 | * skipped over this mm) then we should reactivate it. | |
1037 | */ | |
14fa31b8 | 1038 | if (!(flags & TTU_IGNORE_MLOCK)) { |
caed0f48 KM |
1039 | if (vma->vm_flags & VM_LOCKED) |
1040 | goto out_mlock; | |
1041 | ||
af8e3354 | 1042 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
53f79acb | 1043 | goto out_unmap; |
14fa31b8 AK |
1044 | } |
1045 | if (!(flags & TTU_IGNORE_ACCESS)) { | |
b291f000 NP |
1046 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
1047 | ret = SWAP_FAIL; | |
1048 | goto out_unmap; | |
1049 | } | |
1050 | } | |
1da177e4 | 1051 | |
1da177e4 LT |
1052 | /* Nuke the page table entry. */ |
1053 | flush_cache_page(vma, address, page_to_pfn(page)); | |
cddb8a5c | 1054 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
1055 | |
1056 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
1057 | if (pte_dirty(pteval)) | |
1058 | set_page_dirty(page); | |
1059 | ||
365e9c87 HD |
1060 | /* Update high watermark before we lower rss */ |
1061 | update_hiwater_rss(mm); | |
1062 | ||
888b9f7c AK |
1063 | if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
1064 | if (PageAnon(page)) | |
d559db08 | 1065 | dec_mm_counter(mm, MM_ANONPAGES); |
888b9f7c | 1066 | else |
d559db08 | 1067 | dec_mm_counter(mm, MM_FILEPAGES); |
888b9f7c AK |
1068 | set_pte_at(mm, address, pte, |
1069 | swp_entry_to_pte(make_hwpoison_entry(page))); | |
1070 | } else if (PageAnon(page)) { | |
4c21e2f2 | 1071 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
1072 | |
1073 | if (PageSwapCache(page)) { | |
1074 | /* | |
1075 | * Store the swap location in the pte. | |
1076 | * See handle_pte_fault() ... | |
1077 | */ | |
570a335b HD |
1078 | if (swap_duplicate(entry) < 0) { |
1079 | set_pte_at(mm, address, pte, pteval); | |
1080 | ret = SWAP_FAIL; | |
1081 | goto out_unmap; | |
1082 | } | |
0697212a CL |
1083 | if (list_empty(&mm->mmlist)) { |
1084 | spin_lock(&mmlist_lock); | |
1085 | if (list_empty(&mm->mmlist)) | |
1086 | list_add(&mm->mmlist, &init_mm.mmlist); | |
1087 | spin_unlock(&mmlist_lock); | |
1088 | } | |
d559db08 | 1089 | dec_mm_counter(mm, MM_ANONPAGES); |
b084d435 | 1090 | inc_mm_counter(mm, MM_SWAPENTS); |
64cdd548 | 1091 | } else if (PAGE_MIGRATION) { |
0697212a CL |
1092 | /* |
1093 | * Store the pfn of the page in a special migration | |
1094 | * pte. do_swap_page() will wait until the migration | |
1095 | * pte is removed and then restart fault handling. | |
1096 | */ | |
14fa31b8 | 1097 | BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION); |
0697212a | 1098 | entry = make_migration_entry(page, pte_write(pteval)); |
1da177e4 LT |
1099 | } |
1100 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
1101 | BUG_ON(pte_file(*pte)); | |
14fa31b8 | 1102 | } else if (PAGE_MIGRATION && (TTU_ACTION(flags) == TTU_MIGRATION)) { |
04e62a29 CL |
1103 | /* Establish migration entry for a file page */ |
1104 | swp_entry_t entry; | |
1105 | entry = make_migration_entry(page, pte_write(pteval)); | |
1106 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
1107 | } else | |
d559db08 | 1108 | dec_mm_counter(mm, MM_FILEPAGES); |
1da177e4 | 1109 | |
edc315fd | 1110 | page_remove_rmap(page); |
1da177e4 LT |
1111 | page_cache_release(page); |
1112 | ||
1113 | out_unmap: | |
c0718806 | 1114 | pte_unmap_unlock(pte, ptl); |
caed0f48 KM |
1115 | out: |
1116 | return ret; | |
53f79acb | 1117 | |
caed0f48 KM |
1118 | out_mlock: |
1119 | pte_unmap_unlock(pte, ptl); | |
1120 | ||
1121 | ||
1122 | /* | |
1123 | * We need mmap_sem locking, Otherwise VM_LOCKED check makes | |
1124 | * unstable result and race. Plus, We can't wait here because | |
1125 | * we now hold anon_vma->lock or mapping->i_mmap_lock. | |
1126 | * if trylock failed, the page remain in evictable lru and later | |
1127 | * vmscan could retry to move the page to unevictable lru if the | |
1128 | * page is actually mlocked. | |
1129 | */ | |
1130 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
1131 | if (vma->vm_flags & VM_LOCKED) { | |
1132 | mlock_vma_page(page); | |
1133 | ret = SWAP_MLOCK; | |
53f79acb | 1134 | } |
caed0f48 | 1135 | up_read(&vma->vm_mm->mmap_sem); |
53f79acb | 1136 | } |
1da177e4 LT |
1137 | return ret; |
1138 | } | |
1139 | ||
1140 | /* | |
1141 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
1142 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
1143 | * Consequently, given a particular page and its ->index, we cannot locate the | |
1144 | * ptes which are mapping that page without an exhaustive linear search. | |
1145 | * | |
1146 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
1147 | * maps the file to which the target page belongs. The ->vm_private_data field | |
1148 | * holds the current cursor into that scan. Successive searches will circulate | |
1149 | * around the vma's virtual address space. | |
1150 | * | |
1151 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
1152 | * more scanning pressure is placed against them as well. Eventually pages | |
1153 | * will become fully unmapped and are eligible for eviction. | |
1154 | * | |
1155 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
1156 | * there there won't be many ptes located within the scan cluster. In this case | |
1157 | * maybe we could scan further - to the end of the pte page, perhaps. | |
b291f000 NP |
1158 | * |
1159 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can | |
1160 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, | |
1161 | * rather than unmapping them. If we encounter the "check_page" that vmscan is | |
1162 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. | |
1da177e4 LT |
1163 | */ |
1164 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
1165 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
1166 | ||
b291f000 NP |
1167 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
1168 | struct vm_area_struct *vma, struct page *check_page) | |
1da177e4 LT |
1169 | { |
1170 | struct mm_struct *mm = vma->vm_mm; | |
1171 | pgd_t *pgd; | |
1172 | pud_t *pud; | |
1173 | pmd_t *pmd; | |
c0718806 | 1174 | pte_t *pte; |
1da177e4 | 1175 | pte_t pteval; |
c0718806 | 1176 | spinlock_t *ptl; |
1da177e4 LT |
1177 | struct page *page; |
1178 | unsigned long address; | |
1179 | unsigned long end; | |
b291f000 NP |
1180 | int ret = SWAP_AGAIN; |
1181 | int locked_vma = 0; | |
1da177e4 | 1182 | |
1da177e4 LT |
1183 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
1184 | end = address + CLUSTER_SIZE; | |
1185 | if (address < vma->vm_start) | |
1186 | address = vma->vm_start; | |
1187 | if (end > vma->vm_end) | |
1188 | end = vma->vm_end; | |
1189 | ||
1190 | pgd = pgd_offset(mm, address); | |
1191 | if (!pgd_present(*pgd)) | |
b291f000 | 1192 | return ret; |
1da177e4 LT |
1193 | |
1194 | pud = pud_offset(pgd, address); | |
1195 | if (!pud_present(*pud)) | |
b291f000 | 1196 | return ret; |
1da177e4 LT |
1197 | |
1198 | pmd = pmd_offset(pud, address); | |
1199 | if (!pmd_present(*pmd)) | |
b291f000 NP |
1200 | return ret; |
1201 | ||
1202 | /* | |
af8e3354 | 1203 | * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, |
b291f000 NP |
1204 | * keep the sem while scanning the cluster for mlocking pages. |
1205 | */ | |
af8e3354 | 1206 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
b291f000 NP |
1207 | locked_vma = (vma->vm_flags & VM_LOCKED); |
1208 | if (!locked_vma) | |
1209 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ | |
1210 | } | |
c0718806 HD |
1211 | |
1212 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 1213 | |
365e9c87 HD |
1214 | /* Update high watermark before we lower rss */ |
1215 | update_hiwater_rss(mm); | |
1216 | ||
c0718806 | 1217 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
1218 | if (!pte_present(*pte)) |
1219 | continue; | |
6aab341e LT |
1220 | page = vm_normal_page(vma, address, *pte); |
1221 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 | 1222 | |
b291f000 NP |
1223 | if (locked_vma) { |
1224 | mlock_vma_page(page); /* no-op if already mlocked */ | |
1225 | if (page == check_page) | |
1226 | ret = SWAP_MLOCK; | |
1227 | continue; /* don't unmap */ | |
1228 | } | |
1229 | ||
cddb8a5c | 1230 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1da177e4 LT |
1231 | continue; |
1232 | ||
1233 | /* Nuke the page table entry. */ | |
eca35133 | 1234 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 1235 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
1236 | |
1237 | /* If nonlinear, store the file page offset in the pte. */ | |
1238 | if (page->index != linear_page_index(vma, address)) | |
1239 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
1240 | ||
1241 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
1242 | if (pte_dirty(pteval)) | |
1243 | set_page_dirty(page); | |
1244 | ||
edc315fd | 1245 | page_remove_rmap(page); |
1da177e4 | 1246 | page_cache_release(page); |
d559db08 | 1247 | dec_mm_counter(mm, MM_FILEPAGES); |
1da177e4 LT |
1248 | (*mapcount)--; |
1249 | } | |
c0718806 | 1250 | pte_unmap_unlock(pte - 1, ptl); |
b291f000 NP |
1251 | if (locked_vma) |
1252 | up_read(&vma->vm_mm->mmap_sem); | |
1253 | return ret; | |
1da177e4 LT |
1254 | } |
1255 | ||
71e3aac0 | 1256 | bool is_vma_temporary_stack(struct vm_area_struct *vma) |
a8bef8ff MG |
1257 | { |
1258 | int maybe_stack = vma->vm_flags & (VM_GROWSDOWN | VM_GROWSUP); | |
1259 | ||
1260 | if (!maybe_stack) | |
1261 | return false; | |
1262 | ||
1263 | if ((vma->vm_flags & VM_STACK_INCOMPLETE_SETUP) == | |
1264 | VM_STACK_INCOMPLETE_SETUP) | |
1265 | return true; | |
1266 | ||
1267 | return false; | |
1268 | } | |
1269 | ||
b291f000 NP |
1270 | /** |
1271 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based | |
1272 | * rmap method | |
1273 | * @page: the page to unmap/unlock | |
8051be5e | 1274 | * @flags: action and flags |
b291f000 NP |
1275 | * |
1276 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1277 | * contained in the anon_vma struct it points to. | |
1278 | * | |
1279 | * This function is only called from try_to_unmap/try_to_munlock for | |
1280 | * anonymous pages. | |
1281 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1282 | * where the page was found will be held for write. So, we won't recheck | |
1283 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1284 | * 'LOCKED. | |
1285 | */ | |
14fa31b8 | 1286 | static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1287 | { |
1288 | struct anon_vma *anon_vma; | |
5beb4930 | 1289 | struct anon_vma_chain *avc; |
1da177e4 | 1290 | int ret = SWAP_AGAIN; |
b291f000 | 1291 | |
1da177e4 LT |
1292 | anon_vma = page_lock_anon_vma(page); |
1293 | if (!anon_vma) | |
1294 | return ret; | |
1295 | ||
5beb4930 RR |
1296 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1297 | struct vm_area_struct *vma = avc->vma; | |
a8bef8ff MG |
1298 | unsigned long address; |
1299 | ||
1300 | /* | |
1301 | * During exec, a temporary VMA is setup and later moved. | |
1302 | * The VMA is moved under the anon_vma lock but not the | |
1303 | * page tables leading to a race where migration cannot | |
1304 | * find the migration ptes. Rather than increasing the | |
1305 | * locking requirements of exec(), migration skips | |
1306 | * temporary VMAs until after exec() completes. | |
1307 | */ | |
1308 | if (PAGE_MIGRATION && (flags & TTU_MIGRATION) && | |
1309 | is_vma_temporary_stack(vma)) | |
1310 | continue; | |
1311 | ||
1312 | address = vma_address(page, vma); | |
1cb1729b HD |
1313 | if (address == -EFAULT) |
1314 | continue; | |
1315 | ret = try_to_unmap_one(page, vma, address, flags); | |
53f79acb HD |
1316 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1317 | break; | |
1da177e4 | 1318 | } |
34bbd704 ON |
1319 | |
1320 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
1321 | return ret; |
1322 | } | |
1323 | ||
1324 | /** | |
b291f000 NP |
1325 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
1326 | * @page: the page to unmap/unlock | |
14fa31b8 | 1327 | * @flags: action and flags |
1da177e4 LT |
1328 | * |
1329 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1330 | * contained in the address_space struct it points to. | |
1331 | * | |
b291f000 NP |
1332 | * This function is only called from try_to_unmap/try_to_munlock for |
1333 | * object-based pages. | |
1334 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1335 | * where the page was found will be held for write. So, we won't recheck | |
1336 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1337 | * 'LOCKED. | |
1da177e4 | 1338 | */ |
14fa31b8 | 1339 | static int try_to_unmap_file(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1340 | { |
1341 | struct address_space *mapping = page->mapping; | |
1342 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1343 | struct vm_area_struct *vma; | |
1344 | struct prio_tree_iter iter; | |
1345 | int ret = SWAP_AGAIN; | |
1346 | unsigned long cursor; | |
1347 | unsigned long max_nl_cursor = 0; | |
1348 | unsigned long max_nl_size = 0; | |
1349 | unsigned int mapcount; | |
1350 | ||
1351 | spin_lock(&mapping->i_mmap_lock); | |
1352 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
1cb1729b HD |
1353 | unsigned long address = vma_address(page, vma); |
1354 | if (address == -EFAULT) | |
1355 | continue; | |
1356 | ret = try_to_unmap_one(page, vma, address, flags); | |
53f79acb HD |
1357 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
1358 | goto out; | |
1da177e4 LT |
1359 | } |
1360 | ||
1361 | if (list_empty(&mapping->i_mmap_nonlinear)) | |
1362 | goto out; | |
1363 | ||
53f79acb HD |
1364 | /* |
1365 | * We don't bother to try to find the munlocked page in nonlinears. | |
1366 | * It's costly. Instead, later, page reclaim logic may call | |
1367 | * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily. | |
1368 | */ | |
1369 | if (TTU_ACTION(flags) == TTU_MUNLOCK) | |
1370 | goto out; | |
1371 | ||
1da177e4 LT |
1372 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
1373 | shared.vm_set.list) { | |
1da177e4 LT |
1374 | cursor = (unsigned long) vma->vm_private_data; |
1375 | if (cursor > max_nl_cursor) | |
1376 | max_nl_cursor = cursor; | |
1377 | cursor = vma->vm_end - vma->vm_start; | |
1378 | if (cursor > max_nl_size) | |
1379 | max_nl_size = cursor; | |
1380 | } | |
1381 | ||
b291f000 | 1382 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1da177e4 LT |
1383 | ret = SWAP_FAIL; |
1384 | goto out; | |
1385 | } | |
1386 | ||
1387 | /* | |
1388 | * We don't try to search for this page in the nonlinear vmas, | |
1389 | * and page_referenced wouldn't have found it anyway. Instead | |
1390 | * just walk the nonlinear vmas trying to age and unmap some. | |
1391 | * The mapcount of the page we came in with is irrelevant, | |
1392 | * but even so use it as a guide to how hard we should try? | |
1393 | */ | |
1394 | mapcount = page_mapcount(page); | |
1395 | if (!mapcount) | |
1396 | goto out; | |
1397 | cond_resched_lock(&mapping->i_mmap_lock); | |
1398 | ||
1399 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
1400 | if (max_nl_cursor == 0) | |
1401 | max_nl_cursor = CLUSTER_SIZE; | |
1402 | ||
1403 | do { | |
1404 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
1405 | shared.vm_set.list) { | |
1da177e4 | 1406 | cursor = (unsigned long) vma->vm_private_data; |
839b9685 | 1407 | while ( cursor < max_nl_cursor && |
1da177e4 | 1408 | cursor < vma->vm_end - vma->vm_start) { |
53f79acb HD |
1409 | if (try_to_unmap_cluster(cursor, &mapcount, |
1410 | vma, page) == SWAP_MLOCK) | |
1411 | ret = SWAP_MLOCK; | |
1da177e4 LT |
1412 | cursor += CLUSTER_SIZE; |
1413 | vma->vm_private_data = (void *) cursor; | |
1414 | if ((int)mapcount <= 0) | |
1415 | goto out; | |
1416 | } | |
1417 | vma->vm_private_data = (void *) max_nl_cursor; | |
1418 | } | |
1419 | cond_resched_lock(&mapping->i_mmap_lock); | |
1420 | max_nl_cursor += CLUSTER_SIZE; | |
1421 | } while (max_nl_cursor <= max_nl_size); | |
1422 | ||
1423 | /* | |
1424 | * Don't loop forever (perhaps all the remaining pages are | |
1425 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
1426 | * vmas, now forgetting on which ones it had fallen behind. | |
1427 | */ | |
101d2be7 HD |
1428 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
1429 | vma->vm_private_data = NULL; | |
1da177e4 LT |
1430 | out: |
1431 | spin_unlock(&mapping->i_mmap_lock); | |
1432 | return ret; | |
1433 | } | |
1434 | ||
1435 | /** | |
1436 | * try_to_unmap - try to remove all page table mappings to a page | |
1437 | * @page: the page to get unmapped | |
14fa31b8 | 1438 | * @flags: action and flags |
1da177e4 LT |
1439 | * |
1440 | * Tries to remove all the page table entries which are mapping this | |
1441 | * page, used in the pageout path. Caller must hold the page lock. | |
1442 | * Return values are: | |
1443 | * | |
1444 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
1445 | * SWAP_AGAIN - we missed a mapping, try again later | |
1446 | * SWAP_FAIL - the page is unswappable | |
b291f000 | 1447 | * SWAP_MLOCK - page is mlocked. |
1da177e4 | 1448 | */ |
14fa31b8 | 1449 | int try_to_unmap(struct page *page, enum ttu_flags flags) |
1da177e4 LT |
1450 | { |
1451 | int ret; | |
1452 | ||
1da177e4 | 1453 | BUG_ON(!PageLocked(page)); |
91600e9e | 1454 | VM_BUG_ON(!PageHuge(page) && PageTransHuge(page)); |
1da177e4 | 1455 | |
5ad64688 HD |
1456 | if (unlikely(PageKsm(page))) |
1457 | ret = try_to_unmap_ksm(page, flags); | |
1458 | else if (PageAnon(page)) | |
14fa31b8 | 1459 | ret = try_to_unmap_anon(page, flags); |
1da177e4 | 1460 | else |
14fa31b8 | 1461 | ret = try_to_unmap_file(page, flags); |
b291f000 | 1462 | if (ret != SWAP_MLOCK && !page_mapped(page)) |
1da177e4 LT |
1463 | ret = SWAP_SUCCESS; |
1464 | return ret; | |
1465 | } | |
81b4082d | 1466 | |
b291f000 NP |
1467 | /** |
1468 | * try_to_munlock - try to munlock a page | |
1469 | * @page: the page to be munlocked | |
1470 | * | |
1471 | * Called from munlock code. Checks all of the VMAs mapping the page | |
1472 | * to make sure nobody else has this page mlocked. The page will be | |
1473 | * returned with PG_mlocked cleared if no other vmas have it mlocked. | |
1474 | * | |
1475 | * Return values are: | |
1476 | * | |
53f79acb | 1477 | * SWAP_AGAIN - no vma is holding page mlocked, or, |
b291f000 | 1478 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem |
5ad64688 | 1479 | * SWAP_FAIL - page cannot be located at present |
b291f000 NP |
1480 | * SWAP_MLOCK - page is now mlocked. |
1481 | */ | |
1482 | int try_to_munlock(struct page *page) | |
1483 | { | |
1484 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); | |
1485 | ||
5ad64688 HD |
1486 | if (unlikely(PageKsm(page))) |
1487 | return try_to_unmap_ksm(page, TTU_MUNLOCK); | |
1488 | else if (PageAnon(page)) | |
14fa31b8 | 1489 | return try_to_unmap_anon(page, TTU_MUNLOCK); |
b291f000 | 1490 | else |
14fa31b8 | 1491 | return try_to_unmap_file(page, TTU_MUNLOCK); |
b291f000 | 1492 | } |
e9995ef9 | 1493 | |
01d8b20d | 1494 | void __put_anon_vma(struct anon_vma *anon_vma) |
76545066 | 1495 | { |
01d8b20d | 1496 | struct anon_vma *root = anon_vma->root; |
76545066 | 1497 | |
01d8b20d PZ |
1498 | if (root != anon_vma && atomic_dec_and_test(&root->refcount)) |
1499 | anon_vma_free(root); | |
76545066 | 1500 | |
01d8b20d | 1501 | anon_vma_free(anon_vma); |
76545066 | 1502 | } |
76545066 | 1503 | |
e9995ef9 HD |
1504 | #ifdef CONFIG_MIGRATION |
1505 | /* | |
1506 | * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file(): | |
1507 | * Called by migrate.c to remove migration ptes, but might be used more later. | |
1508 | */ | |
1509 | static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, | |
1510 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1511 | { | |
1512 | struct anon_vma *anon_vma; | |
5beb4930 | 1513 | struct anon_vma_chain *avc; |
e9995ef9 HD |
1514 | int ret = SWAP_AGAIN; |
1515 | ||
1516 | /* | |
1517 | * Note: remove_migration_ptes() cannot use page_lock_anon_vma() | |
1518 | * because that depends on page_mapped(); but not all its usages | |
3f6c8272 MG |
1519 | * are holding mmap_sem. Users without mmap_sem are required to |
1520 | * take a reference count to prevent the anon_vma disappearing | |
e9995ef9 HD |
1521 | */ |
1522 | anon_vma = page_anon_vma(page); | |
1523 | if (!anon_vma) | |
1524 | return ret; | |
cba48b98 | 1525 | anon_vma_lock(anon_vma); |
5beb4930 RR |
1526 | list_for_each_entry(avc, &anon_vma->head, same_anon_vma) { |
1527 | struct vm_area_struct *vma = avc->vma; | |
e9995ef9 HD |
1528 | unsigned long address = vma_address(page, vma); |
1529 | if (address == -EFAULT) | |
1530 | continue; | |
1531 | ret = rmap_one(page, vma, address, arg); | |
1532 | if (ret != SWAP_AGAIN) | |
1533 | break; | |
1534 | } | |
cba48b98 | 1535 | anon_vma_unlock(anon_vma); |
e9995ef9 HD |
1536 | return ret; |
1537 | } | |
1538 | ||
1539 | static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, | |
1540 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1541 | { | |
1542 | struct address_space *mapping = page->mapping; | |
1543 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1544 | struct vm_area_struct *vma; | |
1545 | struct prio_tree_iter iter; | |
1546 | int ret = SWAP_AGAIN; | |
1547 | ||
1548 | if (!mapping) | |
1549 | return ret; | |
1550 | spin_lock(&mapping->i_mmap_lock); | |
1551 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
1552 | unsigned long address = vma_address(page, vma); | |
1553 | if (address == -EFAULT) | |
1554 | continue; | |
1555 | ret = rmap_one(page, vma, address, arg); | |
1556 | if (ret != SWAP_AGAIN) | |
1557 | break; | |
1558 | } | |
1559 | /* | |
1560 | * No nonlinear handling: being always shared, nonlinear vmas | |
1561 | * never contain migration ptes. Decide what to do about this | |
1562 | * limitation to linear when we need rmap_walk() on nonlinear. | |
1563 | */ | |
1564 | spin_unlock(&mapping->i_mmap_lock); | |
1565 | return ret; | |
1566 | } | |
1567 | ||
1568 | int rmap_walk(struct page *page, int (*rmap_one)(struct page *, | |
1569 | struct vm_area_struct *, unsigned long, void *), void *arg) | |
1570 | { | |
1571 | VM_BUG_ON(!PageLocked(page)); | |
1572 | ||
1573 | if (unlikely(PageKsm(page))) | |
1574 | return rmap_walk_ksm(page, rmap_one, arg); | |
1575 | else if (PageAnon(page)) | |
1576 | return rmap_walk_anon(page, rmap_one, arg); | |
1577 | else | |
1578 | return rmap_walk_file(page, rmap_one, arg); | |
1579 | } | |
1580 | #endif /* CONFIG_MIGRATION */ | |
0fe6e20b | 1581 | |
e3390f67 | 1582 | #ifdef CONFIG_HUGETLB_PAGE |
0fe6e20b NH |
1583 | /* |
1584 | * The following three functions are for anonymous (private mapped) hugepages. | |
1585 | * Unlike common anonymous pages, anonymous hugepages have no accounting code | |
1586 | * and no lru code, because we handle hugepages differently from common pages. | |
1587 | */ | |
1588 | static void __hugepage_set_anon_rmap(struct page *page, | |
1589 | struct vm_area_struct *vma, unsigned long address, int exclusive) | |
1590 | { | |
1591 | struct anon_vma *anon_vma = vma->anon_vma; | |
433abed6 | 1592 | |
0fe6e20b | 1593 | BUG_ON(!anon_vma); |
433abed6 NH |
1594 | |
1595 | if (PageAnon(page)) | |
1596 | return; | |
1597 | if (!exclusive) | |
1598 | anon_vma = anon_vma->root; | |
1599 | ||
0fe6e20b NH |
1600 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
1601 | page->mapping = (struct address_space *) anon_vma; | |
1602 | page->index = linear_page_index(vma, address); | |
1603 | } | |
1604 | ||
1605 | void hugepage_add_anon_rmap(struct page *page, | |
1606 | struct vm_area_struct *vma, unsigned long address) | |
1607 | { | |
1608 | struct anon_vma *anon_vma = vma->anon_vma; | |
1609 | int first; | |
a850ea30 NH |
1610 | |
1611 | BUG_ON(!PageLocked(page)); | |
0fe6e20b NH |
1612 | BUG_ON(!anon_vma); |
1613 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
1614 | first = atomic_inc_and_test(&page->_mapcount); | |
1615 | if (first) | |
1616 | __hugepage_set_anon_rmap(page, vma, address, 0); | |
1617 | } | |
1618 | ||
1619 | void hugepage_add_new_anon_rmap(struct page *page, | |
1620 | struct vm_area_struct *vma, unsigned long address) | |
1621 | { | |
1622 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
1623 | atomic_set(&page->_mapcount, 0); | |
1624 | __hugepage_set_anon_rmap(page, vma, address, 1); | |
1625 | } | |
e3390f67 | 1626 | #endif /* CONFIG_HUGETLB_PAGE */ |