Commit | Line | Data |
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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 | |
17 | * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004 | |
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) | |
34 | * inode_lock (in set_page_dirty's __mark_inode_dirty) | |
35 | * sb_lock (within inode_lock in fs/fs-writeback.c) | |
36 | * mapping->tree_lock (widely used, in set_page_dirty, | |
37 | * in arch-dependent flush_dcache_mmap_lock, | |
38 | * within inode_lock in __sync_single_inode) | |
1da177e4 LT |
39 | */ |
40 | ||
41 | #include <linux/mm.h> | |
42 | #include <linux/pagemap.h> | |
43 | #include <linux/swap.h> | |
44 | #include <linux/swapops.h> | |
45 | #include <linux/slab.h> | |
46 | #include <linux/init.h> | |
47 | #include <linux/rmap.h> | |
48 | #include <linux/rcupdate.h> | |
a48d07af | 49 | #include <linux/module.h> |
7de6b805 | 50 | #include <linux/kallsyms.h> |
8a9f3ccd | 51 | #include <linux/memcontrol.h> |
1da177e4 LT |
52 | |
53 | #include <asm/tlbflush.h> | |
54 | ||
fcc234f8 | 55 | struct kmem_cache *anon_vma_cachep; |
1da177e4 | 56 | |
1da177e4 LT |
57 | /* This must be called under the mmap_sem. */ |
58 | int anon_vma_prepare(struct vm_area_struct *vma) | |
59 | { | |
60 | struct anon_vma *anon_vma = vma->anon_vma; | |
61 | ||
62 | might_sleep(); | |
63 | if (unlikely(!anon_vma)) { | |
64 | struct mm_struct *mm = vma->vm_mm; | |
65 | struct anon_vma *allocated, *locked; | |
66 | ||
67 | anon_vma = find_mergeable_anon_vma(vma); | |
68 | if (anon_vma) { | |
69 | allocated = NULL; | |
70 | locked = anon_vma; | |
71 | spin_lock(&locked->lock); | |
72 | } else { | |
73 | anon_vma = anon_vma_alloc(); | |
74 | if (unlikely(!anon_vma)) | |
75 | return -ENOMEM; | |
76 | allocated = anon_vma; | |
77 | locked = NULL; | |
78 | } | |
79 | ||
80 | /* page_table_lock to protect against threads */ | |
81 | spin_lock(&mm->page_table_lock); | |
82 | if (likely(!vma->anon_vma)) { | |
83 | vma->anon_vma = anon_vma; | |
0697212a | 84 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
85 | allocated = NULL; |
86 | } | |
87 | spin_unlock(&mm->page_table_lock); | |
88 | ||
89 | if (locked) | |
90 | spin_unlock(&locked->lock); | |
91 | if (unlikely(allocated)) | |
92 | anon_vma_free(allocated); | |
93 | } | |
94 | return 0; | |
95 | } | |
96 | ||
97 | void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) | |
98 | { | |
99 | BUG_ON(vma->anon_vma != next->anon_vma); | |
100 | list_del(&next->anon_vma_node); | |
101 | } | |
102 | ||
103 | void __anon_vma_link(struct vm_area_struct *vma) | |
104 | { | |
105 | struct anon_vma *anon_vma = vma->anon_vma; | |
106 | ||
30acbaba | 107 | if (anon_vma) |
0697212a | 108 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
109 | } |
110 | ||
111 | void anon_vma_link(struct vm_area_struct *vma) | |
112 | { | |
113 | struct anon_vma *anon_vma = vma->anon_vma; | |
114 | ||
115 | if (anon_vma) { | |
116 | spin_lock(&anon_vma->lock); | |
0697212a | 117 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
118 | spin_unlock(&anon_vma->lock); |
119 | } | |
120 | } | |
121 | ||
122 | void anon_vma_unlink(struct vm_area_struct *vma) | |
123 | { | |
124 | struct anon_vma *anon_vma = vma->anon_vma; | |
125 | int empty; | |
126 | ||
127 | if (!anon_vma) | |
128 | return; | |
129 | ||
130 | spin_lock(&anon_vma->lock); | |
1da177e4 LT |
131 | list_del(&vma->anon_vma_node); |
132 | ||
133 | /* We must garbage collect the anon_vma if it's empty */ | |
134 | empty = list_empty(&anon_vma->head); | |
135 | spin_unlock(&anon_vma->lock); | |
136 | ||
137 | if (empty) | |
138 | anon_vma_free(anon_vma); | |
139 | } | |
140 | ||
4ba9b9d0 | 141 | static void anon_vma_ctor(struct kmem_cache *cachep, void *data) |
1da177e4 | 142 | { |
a35afb83 | 143 | struct anon_vma *anon_vma = data; |
1da177e4 | 144 | |
a35afb83 CL |
145 | spin_lock_init(&anon_vma->lock); |
146 | INIT_LIST_HEAD(&anon_vma->head); | |
1da177e4 LT |
147 | } |
148 | ||
149 | void __init anon_vma_init(void) | |
150 | { | |
151 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 152 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
1da177e4 LT |
153 | } |
154 | ||
155 | /* | |
156 | * Getting a lock on a stable anon_vma from a page off the LRU is | |
157 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. | |
158 | */ | |
159 | static struct anon_vma *page_lock_anon_vma(struct page *page) | |
160 | { | |
34bbd704 | 161 | struct anon_vma *anon_vma; |
1da177e4 LT |
162 | unsigned long anon_mapping; |
163 | ||
164 | rcu_read_lock(); | |
165 | anon_mapping = (unsigned long) page->mapping; | |
166 | if (!(anon_mapping & PAGE_MAPPING_ANON)) | |
167 | goto out; | |
168 | if (!page_mapped(page)) | |
169 | goto out; | |
170 | ||
171 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
172 | spin_lock(&anon_vma->lock); | |
34bbd704 | 173 | return anon_vma; |
1da177e4 LT |
174 | out: |
175 | rcu_read_unlock(); | |
34bbd704 ON |
176 | return NULL; |
177 | } | |
178 | ||
179 | static void page_unlock_anon_vma(struct anon_vma *anon_vma) | |
180 | { | |
181 | spin_unlock(&anon_vma->lock); | |
182 | rcu_read_unlock(); | |
1da177e4 LT |
183 | } |
184 | ||
185 | /* | |
3ad33b24 LS |
186 | * At what user virtual address is page expected in @vma? |
187 | * Returns virtual address or -EFAULT if page's index/offset is not | |
188 | * within the range mapped the @vma. | |
1da177e4 LT |
189 | */ |
190 | static inline unsigned long | |
191 | vma_address(struct page *page, struct vm_area_struct *vma) | |
192 | { | |
193 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
194 | unsigned long address; | |
195 | ||
196 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
197 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { | |
3ad33b24 | 198 | /* page should be within @vma mapping range */ |
1da177e4 LT |
199 | return -EFAULT; |
200 | } | |
201 | return address; | |
202 | } | |
203 | ||
204 | /* | |
205 | * At what user virtual address is page expected in vma? checking that the | |
ee498ed7 | 206 | * page matches the vma: currently only used on anon pages, by unuse_vma; |
1da177e4 LT |
207 | */ |
208 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
209 | { | |
210 | if (PageAnon(page)) { | |
211 | if ((void *)vma->anon_vma != | |
212 | (void *)page->mapping - PAGE_MAPPING_ANON) | |
213 | return -EFAULT; | |
214 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
215 | if (!vma->vm_file || |
216 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
217 | return -EFAULT; |
218 | } else | |
219 | return -EFAULT; | |
220 | return vma_address(page, vma); | |
221 | } | |
222 | ||
81b4082d ND |
223 | /* |
224 | * Check that @page is mapped at @address into @mm. | |
225 | * | |
b8072f09 | 226 | * On success returns with pte mapped and locked. |
81b4082d | 227 | */ |
ceffc078 | 228 | pte_t *page_check_address(struct page *page, struct mm_struct *mm, |
c0718806 | 229 | unsigned long address, spinlock_t **ptlp) |
81b4082d ND |
230 | { |
231 | pgd_t *pgd; | |
232 | pud_t *pud; | |
233 | pmd_t *pmd; | |
234 | pte_t *pte; | |
c0718806 | 235 | spinlock_t *ptl; |
81b4082d | 236 | |
81b4082d | 237 | pgd = pgd_offset(mm, address); |
c0718806 HD |
238 | if (!pgd_present(*pgd)) |
239 | return NULL; | |
240 | ||
241 | pud = pud_offset(pgd, address); | |
242 | if (!pud_present(*pud)) | |
243 | return NULL; | |
244 | ||
245 | pmd = pmd_offset(pud, address); | |
246 | if (!pmd_present(*pmd)) | |
247 | return NULL; | |
248 | ||
249 | pte = pte_offset_map(pmd, address); | |
250 | /* Make a quick check before getting the lock */ | |
251 | if (!pte_present(*pte)) { | |
252 | pte_unmap(pte); | |
253 | return NULL; | |
254 | } | |
255 | ||
4c21e2f2 | 256 | ptl = pte_lockptr(mm, pmd); |
c0718806 HD |
257 | spin_lock(ptl); |
258 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
259 | *ptlp = ptl; | |
260 | return pte; | |
81b4082d | 261 | } |
c0718806 HD |
262 | pte_unmap_unlock(pte, ptl); |
263 | return NULL; | |
81b4082d ND |
264 | } |
265 | ||
1da177e4 LT |
266 | /* |
267 | * Subfunctions of page_referenced: page_referenced_one called | |
268 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
269 | */ | |
270 | static int page_referenced_one(struct page *page, | |
f7b7fd8f | 271 | struct vm_area_struct *vma, unsigned int *mapcount) |
1da177e4 LT |
272 | { |
273 | struct mm_struct *mm = vma->vm_mm; | |
274 | unsigned long address; | |
1da177e4 | 275 | pte_t *pte; |
c0718806 | 276 | spinlock_t *ptl; |
1da177e4 LT |
277 | int referenced = 0; |
278 | ||
1da177e4 LT |
279 | address = vma_address(page, vma); |
280 | if (address == -EFAULT) | |
281 | goto out; | |
282 | ||
c0718806 HD |
283 | pte = page_check_address(page, mm, address, &ptl); |
284 | if (!pte) | |
285 | goto out; | |
1da177e4 | 286 | |
5a9bbdcd HD |
287 | if (vma->vm_flags & VM_LOCKED) { |
288 | referenced++; | |
289 | *mapcount = 1; /* break early from loop */ | |
290 | } else if (ptep_clear_flush_young(vma, address, pte)) | |
c0718806 | 291 | referenced++; |
1da177e4 | 292 | |
c0718806 HD |
293 | /* Pretend the page is referenced if the task has the |
294 | swap token and is in the middle of a page fault. */ | |
f7b7fd8f | 295 | if (mm != current->mm && has_swap_token(mm) && |
c0718806 HD |
296 | rwsem_is_locked(&mm->mmap_sem)) |
297 | referenced++; | |
298 | ||
299 | (*mapcount)--; | |
300 | pte_unmap_unlock(pte, ptl); | |
1da177e4 LT |
301 | out: |
302 | return referenced; | |
303 | } | |
304 | ||
f7b7fd8f | 305 | static int page_referenced_anon(struct page *page) |
1da177e4 LT |
306 | { |
307 | unsigned int mapcount; | |
308 | struct anon_vma *anon_vma; | |
309 | struct vm_area_struct *vma; | |
310 | int referenced = 0; | |
311 | ||
312 | anon_vma = page_lock_anon_vma(page); | |
313 | if (!anon_vma) | |
314 | return referenced; | |
315 | ||
316 | mapcount = page_mapcount(page); | |
317 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
f7b7fd8f | 318 | referenced += page_referenced_one(page, vma, &mapcount); |
1da177e4 LT |
319 | if (!mapcount) |
320 | break; | |
321 | } | |
34bbd704 ON |
322 | |
323 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
324 | return referenced; |
325 | } | |
326 | ||
327 | /** | |
328 | * page_referenced_file - referenced check for object-based rmap | |
329 | * @page: the page we're checking references on. | |
330 | * | |
331 | * For an object-based mapped page, find all the places it is mapped and | |
332 | * check/clear the referenced flag. This is done by following the page->mapping | |
333 | * pointer, then walking the chain of vmas it holds. It returns the number | |
334 | * of references it found. | |
335 | * | |
336 | * This function is only called from page_referenced for object-based pages. | |
337 | */ | |
f7b7fd8f | 338 | static int page_referenced_file(struct page *page) |
1da177e4 LT |
339 | { |
340 | unsigned int mapcount; | |
341 | struct address_space *mapping = page->mapping; | |
342 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
343 | struct vm_area_struct *vma; | |
344 | struct prio_tree_iter iter; | |
345 | int referenced = 0; | |
346 | ||
347 | /* | |
348 | * The caller's checks on page->mapping and !PageAnon have made | |
349 | * sure that this is a file page: the check for page->mapping | |
350 | * excludes the case just before it gets set on an anon page. | |
351 | */ | |
352 | BUG_ON(PageAnon(page)); | |
353 | ||
354 | /* | |
355 | * The page lock not only makes sure that page->mapping cannot | |
356 | * suddenly be NULLified by truncation, it makes sure that the | |
357 | * structure at mapping cannot be freed and reused yet, | |
358 | * so we can safely take mapping->i_mmap_lock. | |
359 | */ | |
360 | BUG_ON(!PageLocked(page)); | |
361 | ||
362 | spin_lock(&mapping->i_mmap_lock); | |
363 | ||
364 | /* | |
365 | * i_mmap_lock does not stabilize mapcount at all, but mapcount | |
366 | * is more likely to be accurate if we note it after spinning. | |
367 | */ | |
368 | mapcount = page_mapcount(page); | |
369 | ||
370 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
371 | if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) | |
372 | == (VM_LOCKED|VM_MAYSHARE)) { | |
373 | referenced++; | |
374 | break; | |
375 | } | |
f7b7fd8f | 376 | referenced += page_referenced_one(page, vma, &mapcount); |
1da177e4 LT |
377 | if (!mapcount) |
378 | break; | |
379 | } | |
380 | ||
381 | spin_unlock(&mapping->i_mmap_lock); | |
382 | return referenced; | |
383 | } | |
384 | ||
385 | /** | |
386 | * page_referenced - test if the page was referenced | |
387 | * @page: the page to test | |
388 | * @is_locked: caller holds lock on the page | |
389 | * | |
390 | * Quick test_and_clear_referenced for all mappings to a page, | |
391 | * returns the number of ptes which referenced the page. | |
392 | */ | |
f7b7fd8f | 393 | int page_referenced(struct page *page, int is_locked) |
1da177e4 LT |
394 | { |
395 | int referenced = 0; | |
396 | ||
1da177e4 LT |
397 | if (page_test_and_clear_young(page)) |
398 | referenced++; | |
399 | ||
400 | if (TestClearPageReferenced(page)) | |
401 | referenced++; | |
402 | ||
403 | if (page_mapped(page) && page->mapping) { | |
404 | if (PageAnon(page)) | |
f7b7fd8f | 405 | referenced += page_referenced_anon(page); |
1da177e4 | 406 | else if (is_locked) |
f7b7fd8f | 407 | referenced += page_referenced_file(page); |
1da177e4 LT |
408 | else if (TestSetPageLocked(page)) |
409 | referenced++; | |
410 | else { | |
411 | if (page->mapping) | |
f7b7fd8f | 412 | referenced += page_referenced_file(page); |
1da177e4 LT |
413 | unlock_page(page); |
414 | } | |
415 | } | |
416 | return referenced; | |
417 | } | |
418 | ||
d08b3851 PZ |
419 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) |
420 | { | |
421 | struct mm_struct *mm = vma->vm_mm; | |
422 | unsigned long address; | |
c2fda5fe | 423 | pte_t *pte; |
d08b3851 PZ |
424 | spinlock_t *ptl; |
425 | int ret = 0; | |
426 | ||
427 | address = vma_address(page, vma); | |
428 | if (address == -EFAULT) | |
429 | goto out; | |
430 | ||
431 | pte = page_check_address(page, mm, address, &ptl); | |
432 | if (!pte) | |
433 | goto out; | |
434 | ||
c2fda5fe PZ |
435 | if (pte_dirty(*pte) || pte_write(*pte)) { |
436 | pte_t entry; | |
d08b3851 | 437 | |
c2fda5fe PZ |
438 | flush_cache_page(vma, address, pte_pfn(*pte)); |
439 | entry = ptep_clear_flush(vma, address, pte); | |
440 | entry = pte_wrprotect(entry); | |
441 | entry = pte_mkclean(entry); | |
d6e88e67 | 442 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
443 | ret = 1; |
444 | } | |
d08b3851 | 445 | |
d08b3851 PZ |
446 | pte_unmap_unlock(pte, ptl); |
447 | out: | |
448 | return ret; | |
449 | } | |
450 | ||
451 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
452 | { | |
453 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
454 | struct vm_area_struct *vma; | |
455 | struct prio_tree_iter iter; | |
456 | int ret = 0; | |
457 | ||
458 | BUG_ON(PageAnon(page)); | |
459 | ||
460 | spin_lock(&mapping->i_mmap_lock); | |
461 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
462 | if (vma->vm_flags & VM_SHARED) | |
463 | ret += page_mkclean_one(page, vma); | |
464 | } | |
465 | spin_unlock(&mapping->i_mmap_lock); | |
466 | return ret; | |
467 | } | |
468 | ||
469 | int page_mkclean(struct page *page) | |
470 | { | |
471 | int ret = 0; | |
472 | ||
473 | BUG_ON(!PageLocked(page)); | |
474 | ||
475 | if (page_mapped(page)) { | |
476 | struct address_space *mapping = page_mapping(page); | |
ce7e9fae | 477 | if (mapping) { |
d08b3851 | 478 | ret = page_mkclean_file(mapping, page); |
ce7e9fae CB |
479 | if (page_test_dirty(page)) { |
480 | page_clear_dirty(page); | |
481 | ret = 1; | |
482 | } | |
6c210482 | 483 | } |
d08b3851 PZ |
484 | } |
485 | ||
486 | return ret; | |
487 | } | |
60b59bea | 488 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 489 | |
9617d95e NP |
490 | /** |
491 | * page_set_anon_rmap - setup new anonymous rmap | |
492 | * @page: the page to add the mapping to | |
493 | * @vma: the vm area in which the mapping is added | |
494 | * @address: the user virtual address mapped | |
495 | */ | |
496 | static void __page_set_anon_rmap(struct page *page, | |
497 | struct vm_area_struct *vma, unsigned long address) | |
498 | { | |
499 | struct anon_vma *anon_vma = vma->anon_vma; | |
500 | ||
501 | BUG_ON(!anon_vma); | |
502 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
503 | page->mapping = (struct address_space *) anon_vma; | |
504 | ||
505 | page->index = linear_page_index(vma, address); | |
506 | ||
a74609fa NP |
507 | /* |
508 | * nr_mapped state can be updated without turning off | |
509 | * interrupts because it is not modified via interrupt. | |
510 | */ | |
f3dbd344 | 511 | __inc_zone_page_state(page, NR_ANON_PAGES); |
9617d95e NP |
512 | } |
513 | ||
c97a9e10 NP |
514 | /** |
515 | * page_set_anon_rmap - sanity check anonymous rmap addition | |
516 | * @page: the page to add the mapping to | |
517 | * @vma: the vm area in which the mapping is added | |
518 | * @address: the user virtual address mapped | |
519 | */ | |
520 | static void __page_check_anon_rmap(struct page *page, | |
521 | struct vm_area_struct *vma, unsigned long address) | |
522 | { | |
523 | #ifdef CONFIG_DEBUG_VM | |
524 | /* | |
525 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
526 | * be set up correctly at this point. | |
527 | * | |
528 | * We have exclusion against page_add_anon_rmap because the caller | |
529 | * always holds the page locked, except if called from page_dup_rmap, | |
530 | * in which case the page is already known to be setup. | |
531 | * | |
532 | * We have exclusion against page_add_new_anon_rmap because those pages | |
533 | * are initially only visible via the pagetables, and the pte is locked | |
534 | * over the call to page_add_new_anon_rmap. | |
535 | */ | |
536 | struct anon_vma *anon_vma = vma->anon_vma; | |
537 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
538 | BUG_ON(page->mapping != (struct address_space *)anon_vma); | |
539 | BUG_ON(page->index != linear_page_index(vma, address)); | |
540 | #endif | |
541 | } | |
542 | ||
1da177e4 LT |
543 | /** |
544 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
545 | * @page: the page to add the mapping to | |
546 | * @vma: the vm area in which the mapping is added | |
547 | * @address: the user virtual address mapped | |
548 | * | |
c97a9e10 | 549 | * The caller needs to hold the pte lock and the page must be locked. |
1da177e4 LT |
550 | */ |
551 | void page_add_anon_rmap(struct page *page, | |
552 | struct vm_area_struct *vma, unsigned long address) | |
553 | { | |
c97a9e10 NP |
554 | VM_BUG_ON(!PageLocked(page)); |
555 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
9617d95e NP |
556 | if (atomic_inc_and_test(&page->_mapcount)) |
557 | __page_set_anon_rmap(page, vma, address); | |
8a9f3ccd | 558 | else { |
c97a9e10 | 559 | __page_check_anon_rmap(page, vma, address); |
8a9f3ccd BS |
560 | /* |
561 | * We unconditionally charged during prepare, we uncharge here | |
562 | * This takes care of balancing the reference counts | |
563 | */ | |
564 | mem_cgroup_uncharge_page(page); | |
565 | } | |
1da177e4 LT |
566 | } |
567 | ||
9617d95e NP |
568 | /* |
569 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page | |
570 | * @page: the page to add the mapping to | |
571 | * @vma: the vm area in which the mapping is added | |
572 | * @address: the user virtual address mapped | |
573 | * | |
574 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
575 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 576 | * Page does not have to be locked. |
9617d95e NP |
577 | */ |
578 | void page_add_new_anon_rmap(struct page *page, | |
579 | struct vm_area_struct *vma, unsigned long address) | |
580 | { | |
c97a9e10 | 581 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
9617d95e NP |
582 | atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ |
583 | __page_set_anon_rmap(page, vma, address); | |
584 | } | |
585 | ||
1da177e4 LT |
586 | /** |
587 | * page_add_file_rmap - add pte mapping to a file page | |
588 | * @page: the page to add the mapping to | |
589 | * | |
b8072f09 | 590 | * The caller needs to hold the pte lock. |
1da177e4 LT |
591 | */ |
592 | void page_add_file_rmap(struct page *page) | |
593 | { | |
1da177e4 | 594 | if (atomic_inc_and_test(&page->_mapcount)) |
65ba55f5 | 595 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
8a9f3ccd BS |
596 | else |
597 | /* | |
598 | * We unconditionally charged during prepare, we uncharge here | |
599 | * This takes care of balancing the reference counts | |
600 | */ | |
601 | mem_cgroup_uncharge_page(page); | |
1da177e4 LT |
602 | } |
603 | ||
c97a9e10 NP |
604 | #ifdef CONFIG_DEBUG_VM |
605 | /** | |
606 | * page_dup_rmap - duplicate pte mapping to a page | |
607 | * @page: the page to add the mapping to | |
608 | * | |
609 | * For copy_page_range only: minimal extract from page_add_file_rmap / | |
610 | * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's | |
611 | * quicker. | |
612 | * | |
613 | * The caller needs to hold the pte lock. | |
614 | */ | |
615 | void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) | |
616 | { | |
617 | BUG_ON(page_mapcount(page) == 0); | |
618 | if (PageAnon(page)) | |
619 | __page_check_anon_rmap(page, vma, address); | |
620 | atomic_inc(&page->_mapcount); | |
621 | } | |
622 | #endif | |
623 | ||
1da177e4 LT |
624 | /** |
625 | * page_remove_rmap - take down pte mapping from a page | |
626 | * @page: page to remove mapping from | |
627 | * | |
b8072f09 | 628 | * The caller needs to hold the pte lock. |
1da177e4 | 629 | */ |
7de6b805 | 630 | void page_remove_rmap(struct page *page, struct vm_area_struct *vma) |
1da177e4 | 631 | { |
1da177e4 | 632 | if (atomic_add_negative(-1, &page->_mapcount)) { |
b7ab795b | 633 | if (unlikely(page_mapcount(page) < 0)) { |
ef2bf0dc | 634 | printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); |
7de6b805 | 635 | printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(page)); |
ef2bf0dc DJ |
636 | printk (KERN_EMERG " page->flags = %lx\n", page->flags); |
637 | printk (KERN_EMERG " page->count = %x\n", page_count(page)); | |
638 | printk (KERN_EMERG " page->mapping = %p\n", page->mapping); | |
7de6b805 | 639 | print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops); |
54cb8821 | 640 | if (vma->vm_ops) { |
7de6b805 | 641 | print_symbol (KERN_EMERG " vma->vm_ops->nopage = %s\n", (unsigned long)vma->vm_ops->nopage); |
54cb8821 NP |
642 | print_symbol (KERN_EMERG " vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault); |
643 | } | |
7de6b805 NP |
644 | if (vma->vm_file && vma->vm_file->f_op) |
645 | print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap); | |
b16bc64d | 646 | BUG(); |
ef2bf0dc | 647 | } |
b16bc64d | 648 | |
1da177e4 LT |
649 | /* |
650 | * It would be tidy to reset the PageAnon mapping here, | |
651 | * but that might overwrite a racing page_add_anon_rmap | |
652 | * which increments mapcount after us but sets mapping | |
653 | * before us: so leave the reset to free_hot_cold_page, | |
654 | * and remember that it's only reliable while mapped. | |
655 | * Leaving it set also helps swapoff to reinstate ptes | |
656 | * faster for those pages still in swapcache. | |
657 | */ | |
6c210482 MS |
658 | if (page_test_dirty(page)) { |
659 | page_clear_dirty(page); | |
1da177e4 | 660 | set_page_dirty(page); |
6c210482 | 661 | } |
8a9f3ccd BS |
662 | mem_cgroup_uncharge_page(page); |
663 | ||
f3dbd344 CL |
664 | __dec_zone_page_state(page, |
665 | PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); | |
1da177e4 LT |
666 | } |
667 | } | |
668 | ||
669 | /* | |
670 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
671 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. | |
672 | */ | |
a48d07af | 673 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
7352349a | 674 | int migration) |
1da177e4 LT |
675 | { |
676 | struct mm_struct *mm = vma->vm_mm; | |
677 | unsigned long address; | |
1da177e4 LT |
678 | pte_t *pte; |
679 | pte_t pteval; | |
c0718806 | 680 | spinlock_t *ptl; |
1da177e4 LT |
681 | int ret = SWAP_AGAIN; |
682 | ||
1da177e4 LT |
683 | address = vma_address(page, vma); |
684 | if (address == -EFAULT) | |
685 | goto out; | |
686 | ||
c0718806 HD |
687 | pte = page_check_address(page, mm, address, &ptl); |
688 | if (!pte) | |
81b4082d | 689 | goto out; |
1da177e4 LT |
690 | |
691 | /* | |
692 | * If the page is mlock()d, we cannot swap it out. | |
693 | * If it's recently referenced (perhaps page_referenced | |
694 | * skipped over this mm) then we should reactivate it. | |
695 | */ | |
e6a1530d CL |
696 | if (!migration && ((vma->vm_flags & VM_LOCKED) || |
697 | (ptep_clear_flush_young(vma, address, pte)))) { | |
1da177e4 LT |
698 | ret = SWAP_FAIL; |
699 | goto out_unmap; | |
700 | } | |
701 | ||
1da177e4 LT |
702 | /* Nuke the page table entry. */ |
703 | flush_cache_page(vma, address, page_to_pfn(page)); | |
704 | pteval = ptep_clear_flush(vma, address, pte); | |
705 | ||
706 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
707 | if (pte_dirty(pteval)) | |
708 | set_page_dirty(page); | |
709 | ||
365e9c87 HD |
710 | /* Update high watermark before we lower rss */ |
711 | update_hiwater_rss(mm); | |
712 | ||
1da177e4 | 713 | if (PageAnon(page)) { |
4c21e2f2 | 714 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
715 | |
716 | if (PageSwapCache(page)) { | |
717 | /* | |
718 | * Store the swap location in the pte. | |
719 | * See handle_pte_fault() ... | |
720 | */ | |
721 | swap_duplicate(entry); | |
722 | if (list_empty(&mm->mmlist)) { | |
723 | spin_lock(&mmlist_lock); | |
724 | if (list_empty(&mm->mmlist)) | |
725 | list_add(&mm->mmlist, &init_mm.mmlist); | |
726 | spin_unlock(&mmlist_lock); | |
727 | } | |
442c9137 | 728 | dec_mm_counter(mm, anon_rss); |
04e62a29 | 729 | #ifdef CONFIG_MIGRATION |
0697212a CL |
730 | } else { |
731 | /* | |
732 | * Store the pfn of the page in a special migration | |
733 | * pte. do_swap_page() will wait until the migration | |
734 | * pte is removed and then restart fault handling. | |
735 | */ | |
736 | BUG_ON(!migration); | |
737 | entry = make_migration_entry(page, pte_write(pteval)); | |
04e62a29 | 738 | #endif |
1da177e4 LT |
739 | } |
740 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
741 | BUG_ON(pte_file(*pte)); | |
4294621f | 742 | } else |
04e62a29 CL |
743 | #ifdef CONFIG_MIGRATION |
744 | if (migration) { | |
745 | /* Establish migration entry for a file page */ | |
746 | swp_entry_t entry; | |
747 | entry = make_migration_entry(page, pte_write(pteval)); | |
748 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
749 | } else | |
750 | #endif | |
4294621f | 751 | dec_mm_counter(mm, file_rss); |
1da177e4 | 752 | |
04e62a29 | 753 | |
7de6b805 | 754 | page_remove_rmap(page, vma); |
1da177e4 LT |
755 | page_cache_release(page); |
756 | ||
757 | out_unmap: | |
c0718806 | 758 | pte_unmap_unlock(pte, ptl); |
1da177e4 LT |
759 | out: |
760 | return ret; | |
761 | } | |
762 | ||
763 | /* | |
764 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
765 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
766 | * Consequently, given a particular page and its ->index, we cannot locate the | |
767 | * ptes which are mapping that page without an exhaustive linear search. | |
768 | * | |
769 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
770 | * maps the file to which the target page belongs. The ->vm_private_data field | |
771 | * holds the current cursor into that scan. Successive searches will circulate | |
772 | * around the vma's virtual address space. | |
773 | * | |
774 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
775 | * more scanning pressure is placed against them as well. Eventually pages | |
776 | * will become fully unmapped and are eligible for eviction. | |
777 | * | |
778 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
779 | * there there won't be many ptes located within the scan cluster. In this case | |
780 | * maybe we could scan further - to the end of the pte page, perhaps. | |
781 | */ | |
782 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
783 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
784 | ||
785 | static void try_to_unmap_cluster(unsigned long cursor, | |
786 | unsigned int *mapcount, struct vm_area_struct *vma) | |
787 | { | |
788 | struct mm_struct *mm = vma->vm_mm; | |
789 | pgd_t *pgd; | |
790 | pud_t *pud; | |
791 | pmd_t *pmd; | |
c0718806 | 792 | pte_t *pte; |
1da177e4 | 793 | pte_t pteval; |
c0718806 | 794 | spinlock_t *ptl; |
1da177e4 LT |
795 | struct page *page; |
796 | unsigned long address; | |
797 | unsigned long end; | |
1da177e4 | 798 | |
1da177e4 LT |
799 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
800 | end = address + CLUSTER_SIZE; | |
801 | if (address < vma->vm_start) | |
802 | address = vma->vm_start; | |
803 | if (end > vma->vm_end) | |
804 | end = vma->vm_end; | |
805 | ||
806 | pgd = pgd_offset(mm, address); | |
807 | if (!pgd_present(*pgd)) | |
c0718806 | 808 | return; |
1da177e4 LT |
809 | |
810 | pud = pud_offset(pgd, address); | |
811 | if (!pud_present(*pud)) | |
c0718806 | 812 | return; |
1da177e4 LT |
813 | |
814 | pmd = pmd_offset(pud, address); | |
815 | if (!pmd_present(*pmd)) | |
c0718806 HD |
816 | return; |
817 | ||
818 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 819 | |
365e9c87 HD |
820 | /* Update high watermark before we lower rss */ |
821 | update_hiwater_rss(mm); | |
822 | ||
c0718806 | 823 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
824 | if (!pte_present(*pte)) |
825 | continue; | |
6aab341e LT |
826 | page = vm_normal_page(vma, address, *pte); |
827 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 LT |
828 | |
829 | if (ptep_clear_flush_young(vma, address, pte)) | |
830 | continue; | |
831 | ||
832 | /* Nuke the page table entry. */ | |
eca35133 | 833 | flush_cache_page(vma, address, pte_pfn(*pte)); |
1da177e4 LT |
834 | pteval = ptep_clear_flush(vma, address, pte); |
835 | ||
836 | /* If nonlinear, store the file page offset in the pte. */ | |
837 | if (page->index != linear_page_index(vma, address)) | |
838 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
839 | ||
840 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
841 | if (pte_dirty(pteval)) | |
842 | set_page_dirty(page); | |
843 | ||
7de6b805 | 844 | page_remove_rmap(page, vma); |
1da177e4 | 845 | page_cache_release(page); |
4294621f | 846 | dec_mm_counter(mm, file_rss); |
1da177e4 LT |
847 | (*mapcount)--; |
848 | } | |
c0718806 | 849 | pte_unmap_unlock(pte - 1, ptl); |
1da177e4 LT |
850 | } |
851 | ||
7352349a | 852 | static int try_to_unmap_anon(struct page *page, int migration) |
1da177e4 LT |
853 | { |
854 | struct anon_vma *anon_vma; | |
855 | struct vm_area_struct *vma; | |
856 | int ret = SWAP_AGAIN; | |
857 | ||
858 | anon_vma = page_lock_anon_vma(page); | |
859 | if (!anon_vma) | |
860 | return ret; | |
861 | ||
862 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
7352349a | 863 | ret = try_to_unmap_one(page, vma, migration); |
1da177e4 LT |
864 | if (ret == SWAP_FAIL || !page_mapped(page)) |
865 | break; | |
866 | } | |
34bbd704 ON |
867 | |
868 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
869 | return ret; |
870 | } | |
871 | ||
872 | /** | |
873 | * try_to_unmap_file - unmap file page using the object-based rmap method | |
874 | * @page: the page to unmap | |
875 | * | |
876 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
877 | * contained in the address_space struct it points to. | |
878 | * | |
879 | * This function is only called from try_to_unmap for object-based pages. | |
880 | */ | |
7352349a | 881 | static int try_to_unmap_file(struct page *page, int migration) |
1da177e4 LT |
882 | { |
883 | struct address_space *mapping = page->mapping; | |
884 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
885 | struct vm_area_struct *vma; | |
886 | struct prio_tree_iter iter; | |
887 | int ret = SWAP_AGAIN; | |
888 | unsigned long cursor; | |
889 | unsigned long max_nl_cursor = 0; | |
890 | unsigned long max_nl_size = 0; | |
891 | unsigned int mapcount; | |
892 | ||
893 | spin_lock(&mapping->i_mmap_lock); | |
894 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
7352349a | 895 | ret = try_to_unmap_one(page, vma, migration); |
1da177e4 LT |
896 | if (ret == SWAP_FAIL || !page_mapped(page)) |
897 | goto out; | |
898 | } | |
899 | ||
900 | if (list_empty(&mapping->i_mmap_nonlinear)) | |
901 | goto out; | |
902 | ||
903 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
904 | shared.vm_set.list) { | |
e6a1530d | 905 | if ((vma->vm_flags & VM_LOCKED) && !migration) |
1da177e4 LT |
906 | continue; |
907 | cursor = (unsigned long) vma->vm_private_data; | |
908 | if (cursor > max_nl_cursor) | |
909 | max_nl_cursor = cursor; | |
910 | cursor = vma->vm_end - vma->vm_start; | |
911 | if (cursor > max_nl_size) | |
912 | max_nl_size = cursor; | |
913 | } | |
914 | ||
915 | if (max_nl_size == 0) { /* any nonlinears locked or reserved */ | |
916 | ret = SWAP_FAIL; | |
917 | goto out; | |
918 | } | |
919 | ||
920 | /* | |
921 | * We don't try to search for this page in the nonlinear vmas, | |
922 | * and page_referenced wouldn't have found it anyway. Instead | |
923 | * just walk the nonlinear vmas trying to age and unmap some. | |
924 | * The mapcount of the page we came in with is irrelevant, | |
925 | * but even so use it as a guide to how hard we should try? | |
926 | */ | |
927 | mapcount = page_mapcount(page); | |
928 | if (!mapcount) | |
929 | goto out; | |
930 | cond_resched_lock(&mapping->i_mmap_lock); | |
931 | ||
932 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
933 | if (max_nl_cursor == 0) | |
934 | max_nl_cursor = CLUSTER_SIZE; | |
935 | ||
936 | do { | |
937 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
938 | shared.vm_set.list) { | |
e6a1530d | 939 | if ((vma->vm_flags & VM_LOCKED) && !migration) |
1da177e4 LT |
940 | continue; |
941 | cursor = (unsigned long) vma->vm_private_data; | |
839b9685 | 942 | while ( cursor < max_nl_cursor && |
1da177e4 LT |
943 | cursor < vma->vm_end - vma->vm_start) { |
944 | try_to_unmap_cluster(cursor, &mapcount, vma); | |
945 | cursor += CLUSTER_SIZE; | |
946 | vma->vm_private_data = (void *) cursor; | |
947 | if ((int)mapcount <= 0) | |
948 | goto out; | |
949 | } | |
950 | vma->vm_private_data = (void *) max_nl_cursor; | |
951 | } | |
952 | cond_resched_lock(&mapping->i_mmap_lock); | |
953 | max_nl_cursor += CLUSTER_SIZE; | |
954 | } while (max_nl_cursor <= max_nl_size); | |
955 | ||
956 | /* | |
957 | * Don't loop forever (perhaps all the remaining pages are | |
958 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
959 | * vmas, now forgetting on which ones it had fallen behind. | |
960 | */ | |
101d2be7 HD |
961 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
962 | vma->vm_private_data = NULL; | |
1da177e4 LT |
963 | out: |
964 | spin_unlock(&mapping->i_mmap_lock); | |
965 | return ret; | |
966 | } | |
967 | ||
968 | /** | |
969 | * try_to_unmap - try to remove all page table mappings to a page | |
970 | * @page: the page to get unmapped | |
971 | * | |
972 | * Tries to remove all the page table entries which are mapping this | |
973 | * page, used in the pageout path. Caller must hold the page lock. | |
974 | * Return values are: | |
975 | * | |
976 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
977 | * SWAP_AGAIN - we missed a mapping, try again later | |
978 | * SWAP_FAIL - the page is unswappable | |
979 | */ | |
7352349a | 980 | int try_to_unmap(struct page *page, int migration) |
1da177e4 LT |
981 | { |
982 | int ret; | |
983 | ||
1da177e4 LT |
984 | BUG_ON(!PageLocked(page)); |
985 | ||
986 | if (PageAnon(page)) | |
7352349a | 987 | ret = try_to_unmap_anon(page, migration); |
1da177e4 | 988 | else |
7352349a | 989 | ret = try_to_unmap_file(page, migration); |
1da177e4 LT |
990 | |
991 | if (!page_mapped(page)) | |
992 | ret = SWAP_SUCCESS; | |
993 | return ret; | |
994 | } | |
81b4082d | 995 |