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> |
cddb8a5c | 52 | #include <linux/mmu_notifier.h> |
1da177e4 LT |
53 | |
54 | #include <asm/tlbflush.h> | |
55 | ||
fcc234f8 | 56 | struct kmem_cache *anon_vma_cachep; |
1da177e4 | 57 | |
1da177e4 LT |
58 | /* This must be called under the mmap_sem. */ |
59 | int anon_vma_prepare(struct vm_area_struct *vma) | |
60 | { | |
61 | struct anon_vma *anon_vma = vma->anon_vma; | |
62 | ||
63 | might_sleep(); | |
64 | if (unlikely(!anon_vma)) { | |
65 | struct mm_struct *mm = vma->vm_mm; | |
66 | struct anon_vma *allocated, *locked; | |
67 | ||
68 | anon_vma = find_mergeable_anon_vma(vma); | |
69 | if (anon_vma) { | |
70 | allocated = NULL; | |
71 | locked = anon_vma; | |
72 | spin_lock(&locked->lock); | |
73 | } else { | |
74 | anon_vma = anon_vma_alloc(); | |
75 | if (unlikely(!anon_vma)) | |
76 | return -ENOMEM; | |
77 | allocated = anon_vma; | |
78 | locked = NULL; | |
79 | } | |
80 | ||
81 | /* page_table_lock to protect against threads */ | |
82 | spin_lock(&mm->page_table_lock); | |
83 | if (likely(!vma->anon_vma)) { | |
84 | vma->anon_vma = anon_vma; | |
0697212a | 85 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
86 | allocated = NULL; |
87 | } | |
88 | spin_unlock(&mm->page_table_lock); | |
89 | ||
90 | if (locked) | |
91 | spin_unlock(&locked->lock); | |
92 | if (unlikely(allocated)) | |
93 | anon_vma_free(allocated); | |
94 | } | |
95 | return 0; | |
96 | } | |
97 | ||
98 | void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) | |
99 | { | |
100 | BUG_ON(vma->anon_vma != next->anon_vma); | |
101 | list_del(&next->anon_vma_node); | |
102 | } | |
103 | ||
104 | void __anon_vma_link(struct vm_area_struct *vma) | |
105 | { | |
106 | struct anon_vma *anon_vma = vma->anon_vma; | |
107 | ||
30acbaba | 108 | if (anon_vma) |
0697212a | 109 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
110 | } |
111 | ||
112 | void anon_vma_link(struct vm_area_struct *vma) | |
113 | { | |
114 | struct anon_vma *anon_vma = vma->anon_vma; | |
115 | ||
116 | if (anon_vma) { | |
117 | spin_lock(&anon_vma->lock); | |
0697212a | 118 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
119 | spin_unlock(&anon_vma->lock); |
120 | } | |
121 | } | |
122 | ||
123 | void anon_vma_unlink(struct vm_area_struct *vma) | |
124 | { | |
125 | struct anon_vma *anon_vma = vma->anon_vma; | |
126 | int empty; | |
127 | ||
128 | if (!anon_vma) | |
129 | return; | |
130 | ||
131 | spin_lock(&anon_vma->lock); | |
1da177e4 LT |
132 | list_del(&vma->anon_vma_node); |
133 | ||
134 | /* We must garbage collect the anon_vma if it's empty */ | |
135 | empty = list_empty(&anon_vma->head); | |
136 | spin_unlock(&anon_vma->lock); | |
137 | ||
138 | if (empty) | |
139 | anon_vma_free(anon_vma); | |
140 | } | |
141 | ||
51cc5068 | 142 | static void anon_vma_ctor(void *data) |
1da177e4 | 143 | { |
a35afb83 | 144 | struct anon_vma *anon_vma = data; |
1da177e4 | 145 | |
a35afb83 CL |
146 | spin_lock_init(&anon_vma->lock); |
147 | INIT_LIST_HEAD(&anon_vma->head); | |
1da177e4 LT |
148 | } |
149 | ||
150 | void __init anon_vma_init(void) | |
151 | { | |
152 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 153 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
1da177e4 LT |
154 | } |
155 | ||
156 | /* | |
157 | * Getting a lock on a stable anon_vma from a page off the LRU is | |
158 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. | |
159 | */ | |
160 | static struct anon_vma *page_lock_anon_vma(struct page *page) | |
161 | { | |
34bbd704 | 162 | struct anon_vma *anon_vma; |
1da177e4 LT |
163 | unsigned long anon_mapping; |
164 | ||
165 | rcu_read_lock(); | |
166 | anon_mapping = (unsigned long) page->mapping; | |
167 | if (!(anon_mapping & PAGE_MAPPING_ANON)) | |
168 | goto out; | |
169 | if (!page_mapped(page)) | |
170 | goto out; | |
171 | ||
172 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
173 | spin_lock(&anon_vma->lock); | |
34bbd704 | 174 | return anon_vma; |
1da177e4 LT |
175 | out: |
176 | rcu_read_unlock(); | |
34bbd704 ON |
177 | return NULL; |
178 | } | |
179 | ||
180 | static void page_unlock_anon_vma(struct anon_vma *anon_vma) | |
181 | { | |
182 | spin_unlock(&anon_vma->lock); | |
183 | rcu_read_unlock(); | |
1da177e4 LT |
184 | } |
185 | ||
186 | /* | |
3ad33b24 LS |
187 | * At what user virtual address is page expected in @vma? |
188 | * Returns virtual address or -EFAULT if page's index/offset is not | |
189 | * within the range mapped the @vma. | |
1da177e4 LT |
190 | */ |
191 | static inline unsigned long | |
192 | vma_address(struct page *page, struct vm_area_struct *vma) | |
193 | { | |
194 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
195 | unsigned long address; | |
196 | ||
197 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
198 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { | |
3ad33b24 | 199 | /* page should be within @vma mapping range */ |
1da177e4 LT |
200 | return -EFAULT; |
201 | } | |
202 | return address; | |
203 | } | |
204 | ||
205 | /* | |
206 | * At what user virtual address is page expected in vma? checking that the | |
ee498ed7 | 207 | * page matches the vma: currently only used on anon pages, by unuse_vma; |
1da177e4 LT |
208 | */ |
209 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
210 | { | |
211 | if (PageAnon(page)) { | |
212 | if ((void *)vma->anon_vma != | |
213 | (void *)page->mapping - PAGE_MAPPING_ANON) | |
214 | return -EFAULT; | |
215 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
216 | if (!vma->vm_file || |
217 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
218 | return -EFAULT; |
219 | } else | |
220 | return -EFAULT; | |
221 | return vma_address(page, vma); | |
222 | } | |
223 | ||
81b4082d ND |
224 | /* |
225 | * Check that @page is mapped at @address into @mm. | |
226 | * | |
b8072f09 | 227 | * On success returns with pte mapped and locked. |
81b4082d | 228 | */ |
ceffc078 | 229 | pte_t *page_check_address(struct page *page, struct mm_struct *mm, |
c0718806 | 230 | unsigned long address, spinlock_t **ptlp) |
81b4082d ND |
231 | { |
232 | pgd_t *pgd; | |
233 | pud_t *pud; | |
234 | pmd_t *pmd; | |
235 | pte_t *pte; | |
c0718806 | 236 | spinlock_t *ptl; |
81b4082d | 237 | |
81b4082d | 238 | pgd = pgd_offset(mm, address); |
c0718806 HD |
239 | if (!pgd_present(*pgd)) |
240 | return NULL; | |
241 | ||
242 | pud = pud_offset(pgd, address); | |
243 | if (!pud_present(*pud)) | |
244 | return NULL; | |
245 | ||
246 | pmd = pmd_offset(pud, address); | |
247 | if (!pmd_present(*pmd)) | |
248 | return NULL; | |
249 | ||
250 | pte = pte_offset_map(pmd, address); | |
251 | /* Make a quick check before getting the lock */ | |
252 | if (!pte_present(*pte)) { | |
253 | pte_unmap(pte); | |
254 | return NULL; | |
255 | } | |
256 | ||
4c21e2f2 | 257 | ptl = pte_lockptr(mm, pmd); |
c0718806 HD |
258 | spin_lock(ptl); |
259 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
260 | *ptlp = ptl; | |
261 | return pte; | |
81b4082d | 262 | } |
c0718806 HD |
263 | pte_unmap_unlock(pte, ptl); |
264 | return NULL; | |
81b4082d ND |
265 | } |
266 | ||
1da177e4 LT |
267 | /* |
268 | * Subfunctions of page_referenced: page_referenced_one called | |
269 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
270 | */ | |
271 | static int page_referenced_one(struct page *page, | |
f7b7fd8f | 272 | struct vm_area_struct *vma, unsigned int *mapcount) |
1da177e4 LT |
273 | { |
274 | struct mm_struct *mm = vma->vm_mm; | |
275 | unsigned long address; | |
1da177e4 | 276 | pte_t *pte; |
c0718806 | 277 | spinlock_t *ptl; |
1da177e4 LT |
278 | int referenced = 0; |
279 | ||
1da177e4 LT |
280 | address = vma_address(page, vma); |
281 | if (address == -EFAULT) | |
282 | goto out; | |
283 | ||
c0718806 HD |
284 | pte = page_check_address(page, mm, address, &ptl); |
285 | if (!pte) | |
286 | goto out; | |
1da177e4 | 287 | |
5a9bbdcd HD |
288 | if (vma->vm_flags & VM_LOCKED) { |
289 | referenced++; | |
290 | *mapcount = 1; /* break early from loop */ | |
cddb8a5c | 291 | } else if (ptep_clear_flush_young_notify(vma, address, pte)) |
c0718806 | 292 | referenced++; |
1da177e4 | 293 | |
c0718806 HD |
294 | /* Pretend the page is referenced if the task has the |
295 | swap token and is in the middle of a page fault. */ | |
f7b7fd8f | 296 | if (mm != current->mm && has_swap_token(mm) && |
c0718806 HD |
297 | rwsem_is_locked(&mm->mmap_sem)) |
298 | referenced++; | |
299 | ||
300 | (*mapcount)--; | |
301 | pte_unmap_unlock(pte, ptl); | |
1da177e4 LT |
302 | out: |
303 | return referenced; | |
304 | } | |
305 | ||
bed7161a BS |
306 | static int page_referenced_anon(struct page *page, |
307 | struct mem_cgroup *mem_cont) | |
1da177e4 LT |
308 | { |
309 | unsigned int mapcount; | |
310 | struct anon_vma *anon_vma; | |
311 | struct vm_area_struct *vma; | |
312 | int referenced = 0; | |
313 | ||
314 | anon_vma = page_lock_anon_vma(page); | |
315 | if (!anon_vma) | |
316 | return referenced; | |
317 | ||
318 | mapcount = page_mapcount(page); | |
319 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
bed7161a BS |
320 | /* |
321 | * If we are reclaiming on behalf of a cgroup, skip | |
322 | * counting on behalf of references from different | |
323 | * cgroups | |
324 | */ | |
bd845e38 | 325 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 326 | continue; |
f7b7fd8f | 327 | referenced += page_referenced_one(page, vma, &mapcount); |
1da177e4 LT |
328 | if (!mapcount) |
329 | break; | |
330 | } | |
34bbd704 ON |
331 | |
332 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
333 | return referenced; |
334 | } | |
335 | ||
336 | /** | |
337 | * page_referenced_file - referenced check for object-based rmap | |
338 | * @page: the page we're checking references on. | |
43d8eac4 | 339 | * @mem_cont: target memory controller |
1da177e4 LT |
340 | * |
341 | * For an object-based mapped page, find all the places it is mapped and | |
342 | * check/clear the referenced flag. This is done by following the page->mapping | |
343 | * pointer, then walking the chain of vmas it holds. It returns the number | |
344 | * of references it found. | |
345 | * | |
346 | * This function is only called from page_referenced for object-based pages. | |
347 | */ | |
bed7161a BS |
348 | static int page_referenced_file(struct page *page, |
349 | struct mem_cgroup *mem_cont) | |
1da177e4 LT |
350 | { |
351 | unsigned int mapcount; | |
352 | struct address_space *mapping = page->mapping; | |
353 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
354 | struct vm_area_struct *vma; | |
355 | struct prio_tree_iter iter; | |
356 | int referenced = 0; | |
357 | ||
358 | /* | |
359 | * The caller's checks on page->mapping and !PageAnon have made | |
360 | * sure that this is a file page: the check for page->mapping | |
361 | * excludes the case just before it gets set on an anon page. | |
362 | */ | |
363 | BUG_ON(PageAnon(page)); | |
364 | ||
365 | /* | |
366 | * The page lock not only makes sure that page->mapping cannot | |
367 | * suddenly be NULLified by truncation, it makes sure that the | |
368 | * structure at mapping cannot be freed and reused yet, | |
369 | * so we can safely take mapping->i_mmap_lock. | |
370 | */ | |
371 | BUG_ON(!PageLocked(page)); | |
372 | ||
373 | spin_lock(&mapping->i_mmap_lock); | |
374 | ||
375 | /* | |
376 | * i_mmap_lock does not stabilize mapcount at all, but mapcount | |
377 | * is more likely to be accurate if we note it after spinning. | |
378 | */ | |
379 | mapcount = page_mapcount(page); | |
380 | ||
381 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
bed7161a BS |
382 | /* |
383 | * If we are reclaiming on behalf of a cgroup, skip | |
384 | * counting on behalf of references from different | |
385 | * cgroups | |
386 | */ | |
bd845e38 | 387 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 388 | continue; |
1da177e4 LT |
389 | if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) |
390 | == (VM_LOCKED|VM_MAYSHARE)) { | |
391 | referenced++; | |
392 | break; | |
393 | } | |
f7b7fd8f | 394 | referenced += page_referenced_one(page, vma, &mapcount); |
1da177e4 LT |
395 | if (!mapcount) |
396 | break; | |
397 | } | |
398 | ||
399 | spin_unlock(&mapping->i_mmap_lock); | |
400 | return referenced; | |
401 | } | |
402 | ||
403 | /** | |
404 | * page_referenced - test if the page was referenced | |
405 | * @page: the page to test | |
406 | * @is_locked: caller holds lock on the page | |
43d8eac4 | 407 | * @mem_cont: target memory controller |
1da177e4 LT |
408 | * |
409 | * Quick test_and_clear_referenced for all mappings to a page, | |
410 | * returns the number of ptes which referenced the page. | |
411 | */ | |
bed7161a BS |
412 | int page_referenced(struct page *page, int is_locked, |
413 | struct mem_cgroup *mem_cont) | |
1da177e4 LT |
414 | { |
415 | int referenced = 0; | |
416 | ||
1da177e4 LT |
417 | if (TestClearPageReferenced(page)) |
418 | referenced++; | |
419 | ||
420 | if (page_mapped(page) && page->mapping) { | |
421 | if (PageAnon(page)) | |
bed7161a | 422 | referenced += page_referenced_anon(page, mem_cont); |
1da177e4 | 423 | else if (is_locked) |
bed7161a | 424 | referenced += page_referenced_file(page, mem_cont); |
529ae9aa | 425 | else if (!trylock_page(page)) |
1da177e4 LT |
426 | referenced++; |
427 | else { | |
428 | if (page->mapping) | |
bed7161a BS |
429 | referenced += |
430 | page_referenced_file(page, mem_cont); | |
1da177e4 LT |
431 | unlock_page(page); |
432 | } | |
433 | } | |
5b7baf05 CB |
434 | |
435 | if (page_test_and_clear_young(page)) | |
436 | referenced++; | |
437 | ||
1da177e4 LT |
438 | return referenced; |
439 | } | |
440 | ||
d08b3851 PZ |
441 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) |
442 | { | |
443 | struct mm_struct *mm = vma->vm_mm; | |
444 | unsigned long address; | |
c2fda5fe | 445 | pte_t *pte; |
d08b3851 PZ |
446 | spinlock_t *ptl; |
447 | int ret = 0; | |
448 | ||
449 | address = vma_address(page, vma); | |
450 | if (address == -EFAULT) | |
451 | goto out; | |
452 | ||
453 | pte = page_check_address(page, mm, address, &ptl); | |
454 | if (!pte) | |
455 | goto out; | |
456 | ||
c2fda5fe PZ |
457 | if (pte_dirty(*pte) || pte_write(*pte)) { |
458 | pte_t entry; | |
d08b3851 | 459 | |
c2fda5fe | 460 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 461 | entry = ptep_clear_flush_notify(vma, address, pte); |
c2fda5fe PZ |
462 | entry = pte_wrprotect(entry); |
463 | entry = pte_mkclean(entry); | |
d6e88e67 | 464 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
465 | ret = 1; |
466 | } | |
d08b3851 | 467 | |
d08b3851 PZ |
468 | pte_unmap_unlock(pte, ptl); |
469 | out: | |
470 | return ret; | |
471 | } | |
472 | ||
473 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
474 | { | |
475 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
476 | struct vm_area_struct *vma; | |
477 | struct prio_tree_iter iter; | |
478 | int ret = 0; | |
479 | ||
480 | BUG_ON(PageAnon(page)); | |
481 | ||
482 | spin_lock(&mapping->i_mmap_lock); | |
483 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
484 | if (vma->vm_flags & VM_SHARED) | |
485 | ret += page_mkclean_one(page, vma); | |
486 | } | |
487 | spin_unlock(&mapping->i_mmap_lock); | |
488 | return ret; | |
489 | } | |
490 | ||
491 | int page_mkclean(struct page *page) | |
492 | { | |
493 | int ret = 0; | |
494 | ||
495 | BUG_ON(!PageLocked(page)); | |
496 | ||
497 | if (page_mapped(page)) { | |
498 | struct address_space *mapping = page_mapping(page); | |
ce7e9fae | 499 | if (mapping) { |
d08b3851 | 500 | ret = page_mkclean_file(mapping, page); |
ce7e9fae CB |
501 | if (page_test_dirty(page)) { |
502 | page_clear_dirty(page); | |
503 | ret = 1; | |
504 | } | |
6c210482 | 505 | } |
d08b3851 PZ |
506 | } |
507 | ||
508 | return ret; | |
509 | } | |
60b59bea | 510 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 511 | |
9617d95e | 512 | /** |
43d8eac4 | 513 | * __page_set_anon_rmap - setup new anonymous rmap |
9617d95e NP |
514 | * @page: the page to add the mapping to |
515 | * @vma: the vm area in which the mapping is added | |
516 | * @address: the user virtual address mapped | |
517 | */ | |
518 | static void __page_set_anon_rmap(struct page *page, | |
519 | struct vm_area_struct *vma, unsigned long address) | |
520 | { | |
521 | struct anon_vma *anon_vma = vma->anon_vma; | |
522 | ||
523 | BUG_ON(!anon_vma); | |
524 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
525 | page->mapping = (struct address_space *) anon_vma; | |
526 | ||
527 | page->index = linear_page_index(vma, address); | |
528 | ||
a74609fa NP |
529 | /* |
530 | * nr_mapped state can be updated without turning off | |
531 | * interrupts because it is not modified via interrupt. | |
532 | */ | |
f3dbd344 | 533 | __inc_zone_page_state(page, NR_ANON_PAGES); |
9617d95e NP |
534 | } |
535 | ||
c97a9e10 | 536 | /** |
43d8eac4 | 537 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
c97a9e10 NP |
538 | * @page: the page to add the mapping to |
539 | * @vma: the vm area in which the mapping is added | |
540 | * @address: the user virtual address mapped | |
541 | */ | |
542 | static void __page_check_anon_rmap(struct page *page, | |
543 | struct vm_area_struct *vma, unsigned long address) | |
544 | { | |
545 | #ifdef CONFIG_DEBUG_VM | |
546 | /* | |
547 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
548 | * be set up correctly at this point. | |
549 | * | |
550 | * We have exclusion against page_add_anon_rmap because the caller | |
551 | * always holds the page locked, except if called from page_dup_rmap, | |
552 | * in which case the page is already known to be setup. | |
553 | * | |
554 | * We have exclusion against page_add_new_anon_rmap because those pages | |
555 | * are initially only visible via the pagetables, and the pte is locked | |
556 | * over the call to page_add_new_anon_rmap. | |
557 | */ | |
558 | struct anon_vma *anon_vma = vma->anon_vma; | |
559 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
560 | BUG_ON(page->mapping != (struct address_space *)anon_vma); | |
561 | BUG_ON(page->index != linear_page_index(vma, address)); | |
562 | #endif | |
563 | } | |
564 | ||
1da177e4 LT |
565 | /** |
566 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
567 | * @page: the page to add the mapping to | |
568 | * @vma: the vm area in which the mapping is added | |
569 | * @address: the user virtual address mapped | |
570 | * | |
c97a9e10 | 571 | * The caller needs to hold the pte lock and the page must be locked. |
1da177e4 LT |
572 | */ |
573 | void page_add_anon_rmap(struct page *page, | |
574 | struct vm_area_struct *vma, unsigned long address) | |
575 | { | |
c97a9e10 NP |
576 | VM_BUG_ON(!PageLocked(page)); |
577 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
9617d95e NP |
578 | if (atomic_inc_and_test(&page->_mapcount)) |
579 | __page_set_anon_rmap(page, vma, address); | |
69029cd5 | 580 | else |
c97a9e10 | 581 | __page_check_anon_rmap(page, vma, address); |
1da177e4 LT |
582 | } |
583 | ||
43d8eac4 | 584 | /** |
9617d95e NP |
585 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
586 | * @page: the page to add the mapping to | |
587 | * @vma: the vm area in which the mapping is added | |
588 | * @address: the user virtual address mapped | |
589 | * | |
590 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
591 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 592 | * Page does not have to be locked. |
9617d95e NP |
593 | */ |
594 | void page_add_new_anon_rmap(struct page *page, | |
595 | struct vm_area_struct *vma, unsigned long address) | |
596 | { | |
c97a9e10 | 597 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
9617d95e NP |
598 | atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ |
599 | __page_set_anon_rmap(page, vma, address); | |
600 | } | |
601 | ||
1da177e4 LT |
602 | /** |
603 | * page_add_file_rmap - add pte mapping to a file page | |
604 | * @page: the page to add the mapping to | |
605 | * | |
b8072f09 | 606 | * The caller needs to hold the pte lock. |
1da177e4 LT |
607 | */ |
608 | void page_add_file_rmap(struct page *page) | |
609 | { | |
1da177e4 | 610 | if (atomic_inc_and_test(&page->_mapcount)) |
65ba55f5 | 611 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
1da177e4 LT |
612 | } |
613 | ||
c97a9e10 NP |
614 | #ifdef CONFIG_DEBUG_VM |
615 | /** | |
616 | * page_dup_rmap - duplicate pte mapping to a page | |
617 | * @page: the page to add the mapping to | |
43d8eac4 RD |
618 | * @vma: the vm area being duplicated |
619 | * @address: the user virtual address mapped | |
c97a9e10 NP |
620 | * |
621 | * For copy_page_range only: minimal extract from page_add_file_rmap / | |
622 | * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's | |
623 | * quicker. | |
624 | * | |
625 | * The caller needs to hold the pte lock. | |
626 | */ | |
627 | void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) | |
628 | { | |
629 | BUG_ON(page_mapcount(page) == 0); | |
630 | if (PageAnon(page)) | |
631 | __page_check_anon_rmap(page, vma, address); | |
632 | atomic_inc(&page->_mapcount); | |
633 | } | |
634 | #endif | |
635 | ||
1da177e4 LT |
636 | /** |
637 | * page_remove_rmap - take down pte mapping from a page | |
638 | * @page: page to remove mapping from | |
43d8eac4 | 639 | * @vma: the vm area in which the mapping is removed |
1da177e4 | 640 | * |
b8072f09 | 641 | * The caller needs to hold the pte lock. |
1da177e4 | 642 | */ |
7de6b805 | 643 | void page_remove_rmap(struct page *page, struct vm_area_struct *vma) |
1da177e4 | 644 | { |
1da177e4 | 645 | if (atomic_add_negative(-1, &page->_mapcount)) { |
b7ab795b | 646 | if (unlikely(page_mapcount(page) < 0)) { |
ef2bf0dc | 647 | printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); |
7de6b805 | 648 | printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(page)); |
ef2bf0dc DJ |
649 | printk (KERN_EMERG " page->flags = %lx\n", page->flags); |
650 | printk (KERN_EMERG " page->count = %x\n", page_count(page)); | |
651 | printk (KERN_EMERG " page->mapping = %p\n", page->mapping); | |
7de6b805 | 652 | print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops); |
54cb8821 | 653 | if (vma->vm_ops) { |
54cb8821 NP |
654 | print_symbol (KERN_EMERG " vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault); |
655 | } | |
7de6b805 NP |
656 | if (vma->vm_file && vma->vm_file->f_op) |
657 | print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap); | |
b16bc64d | 658 | BUG(); |
ef2bf0dc | 659 | } |
b16bc64d | 660 | |
1da177e4 LT |
661 | /* |
662 | * It would be tidy to reset the PageAnon mapping here, | |
663 | * but that might overwrite a racing page_add_anon_rmap | |
664 | * which increments mapcount after us but sets mapping | |
665 | * before us: so leave the reset to free_hot_cold_page, | |
666 | * and remember that it's only reliable while mapped. | |
667 | * Leaving it set also helps swapoff to reinstate ptes | |
668 | * faster for those pages still in swapcache. | |
669 | */ | |
a4b526b3 MS |
670 | if ((!PageAnon(page) || PageSwapCache(page)) && |
671 | page_test_dirty(page)) { | |
6c210482 | 672 | page_clear_dirty(page); |
1da177e4 | 673 | set_page_dirty(page); |
6c210482 | 674 | } |
8a9f3ccd BS |
675 | mem_cgroup_uncharge_page(page); |
676 | ||
f3dbd344 CL |
677 | __dec_zone_page_state(page, |
678 | PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); | |
1da177e4 LT |
679 | } |
680 | } | |
681 | ||
682 | /* | |
683 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
684 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. | |
685 | */ | |
a48d07af | 686 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
7352349a | 687 | int migration) |
1da177e4 LT |
688 | { |
689 | struct mm_struct *mm = vma->vm_mm; | |
690 | unsigned long address; | |
1da177e4 LT |
691 | pte_t *pte; |
692 | pte_t pteval; | |
c0718806 | 693 | spinlock_t *ptl; |
1da177e4 LT |
694 | int ret = SWAP_AGAIN; |
695 | ||
1da177e4 LT |
696 | address = vma_address(page, vma); |
697 | if (address == -EFAULT) | |
698 | goto out; | |
699 | ||
c0718806 HD |
700 | pte = page_check_address(page, mm, address, &ptl); |
701 | if (!pte) | |
81b4082d | 702 | goto out; |
1da177e4 LT |
703 | |
704 | /* | |
705 | * If the page is mlock()d, we cannot swap it out. | |
706 | * If it's recently referenced (perhaps page_referenced | |
707 | * skipped over this mm) then we should reactivate it. | |
708 | */ | |
e6a1530d | 709 | if (!migration && ((vma->vm_flags & VM_LOCKED) || |
cddb8a5c | 710 | (ptep_clear_flush_young_notify(vma, address, pte)))) { |
1da177e4 LT |
711 | ret = SWAP_FAIL; |
712 | goto out_unmap; | |
713 | } | |
714 | ||
1da177e4 LT |
715 | /* Nuke the page table entry. */ |
716 | flush_cache_page(vma, address, page_to_pfn(page)); | |
cddb8a5c | 717 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
718 | |
719 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
720 | if (pte_dirty(pteval)) | |
721 | set_page_dirty(page); | |
722 | ||
365e9c87 HD |
723 | /* Update high watermark before we lower rss */ |
724 | update_hiwater_rss(mm); | |
725 | ||
1da177e4 | 726 | if (PageAnon(page)) { |
4c21e2f2 | 727 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
728 | |
729 | if (PageSwapCache(page)) { | |
730 | /* | |
731 | * Store the swap location in the pte. | |
732 | * See handle_pte_fault() ... | |
733 | */ | |
734 | swap_duplicate(entry); | |
735 | if (list_empty(&mm->mmlist)) { | |
736 | spin_lock(&mmlist_lock); | |
737 | if (list_empty(&mm->mmlist)) | |
738 | list_add(&mm->mmlist, &init_mm.mmlist); | |
739 | spin_unlock(&mmlist_lock); | |
740 | } | |
442c9137 | 741 | dec_mm_counter(mm, anon_rss); |
04e62a29 | 742 | #ifdef CONFIG_MIGRATION |
0697212a CL |
743 | } else { |
744 | /* | |
745 | * Store the pfn of the page in a special migration | |
746 | * pte. do_swap_page() will wait until the migration | |
747 | * pte is removed and then restart fault handling. | |
748 | */ | |
749 | BUG_ON(!migration); | |
750 | entry = make_migration_entry(page, pte_write(pteval)); | |
04e62a29 | 751 | #endif |
1da177e4 LT |
752 | } |
753 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
754 | BUG_ON(pte_file(*pte)); | |
4294621f | 755 | } else |
04e62a29 CL |
756 | #ifdef CONFIG_MIGRATION |
757 | if (migration) { | |
758 | /* Establish migration entry for a file page */ | |
759 | swp_entry_t entry; | |
760 | entry = make_migration_entry(page, pte_write(pteval)); | |
761 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
762 | } else | |
763 | #endif | |
4294621f | 764 | dec_mm_counter(mm, file_rss); |
1da177e4 | 765 | |
04e62a29 | 766 | |
7de6b805 | 767 | page_remove_rmap(page, vma); |
1da177e4 LT |
768 | page_cache_release(page); |
769 | ||
770 | out_unmap: | |
c0718806 | 771 | pte_unmap_unlock(pte, ptl); |
1da177e4 LT |
772 | out: |
773 | return ret; | |
774 | } | |
775 | ||
776 | /* | |
777 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
778 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
779 | * Consequently, given a particular page and its ->index, we cannot locate the | |
780 | * ptes which are mapping that page without an exhaustive linear search. | |
781 | * | |
782 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
783 | * maps the file to which the target page belongs. The ->vm_private_data field | |
784 | * holds the current cursor into that scan. Successive searches will circulate | |
785 | * around the vma's virtual address space. | |
786 | * | |
787 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
788 | * more scanning pressure is placed against them as well. Eventually pages | |
789 | * will become fully unmapped and are eligible for eviction. | |
790 | * | |
791 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
792 | * there there won't be many ptes located within the scan cluster. In this case | |
793 | * maybe we could scan further - to the end of the pte page, perhaps. | |
794 | */ | |
795 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
796 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
797 | ||
798 | static void try_to_unmap_cluster(unsigned long cursor, | |
799 | unsigned int *mapcount, struct vm_area_struct *vma) | |
800 | { | |
801 | struct mm_struct *mm = vma->vm_mm; | |
802 | pgd_t *pgd; | |
803 | pud_t *pud; | |
804 | pmd_t *pmd; | |
c0718806 | 805 | pte_t *pte; |
1da177e4 | 806 | pte_t pteval; |
c0718806 | 807 | spinlock_t *ptl; |
1da177e4 LT |
808 | struct page *page; |
809 | unsigned long address; | |
810 | unsigned long end; | |
1da177e4 | 811 | |
1da177e4 LT |
812 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
813 | end = address + CLUSTER_SIZE; | |
814 | if (address < vma->vm_start) | |
815 | address = vma->vm_start; | |
816 | if (end > vma->vm_end) | |
817 | end = vma->vm_end; | |
818 | ||
819 | pgd = pgd_offset(mm, address); | |
820 | if (!pgd_present(*pgd)) | |
c0718806 | 821 | return; |
1da177e4 LT |
822 | |
823 | pud = pud_offset(pgd, address); | |
824 | if (!pud_present(*pud)) | |
c0718806 | 825 | return; |
1da177e4 LT |
826 | |
827 | pmd = pmd_offset(pud, address); | |
828 | if (!pmd_present(*pmd)) | |
c0718806 HD |
829 | return; |
830 | ||
831 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 832 | |
365e9c87 HD |
833 | /* Update high watermark before we lower rss */ |
834 | update_hiwater_rss(mm); | |
835 | ||
c0718806 | 836 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
837 | if (!pte_present(*pte)) |
838 | continue; | |
6aab341e LT |
839 | page = vm_normal_page(vma, address, *pte); |
840 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 | 841 | |
cddb8a5c | 842 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1da177e4 LT |
843 | continue; |
844 | ||
845 | /* Nuke the page table entry. */ | |
eca35133 | 846 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 847 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
848 | |
849 | /* If nonlinear, store the file page offset in the pte. */ | |
850 | if (page->index != linear_page_index(vma, address)) | |
851 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
852 | ||
853 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
854 | if (pte_dirty(pteval)) | |
855 | set_page_dirty(page); | |
856 | ||
7de6b805 | 857 | page_remove_rmap(page, vma); |
1da177e4 | 858 | page_cache_release(page); |
4294621f | 859 | dec_mm_counter(mm, file_rss); |
1da177e4 LT |
860 | (*mapcount)--; |
861 | } | |
c0718806 | 862 | pte_unmap_unlock(pte - 1, ptl); |
1da177e4 LT |
863 | } |
864 | ||
7352349a | 865 | static int try_to_unmap_anon(struct page *page, int migration) |
1da177e4 LT |
866 | { |
867 | struct anon_vma *anon_vma; | |
868 | struct vm_area_struct *vma; | |
869 | int ret = SWAP_AGAIN; | |
870 | ||
871 | anon_vma = page_lock_anon_vma(page); | |
872 | if (!anon_vma) | |
873 | return ret; | |
874 | ||
875 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
7352349a | 876 | ret = try_to_unmap_one(page, vma, migration); |
1da177e4 LT |
877 | if (ret == SWAP_FAIL || !page_mapped(page)) |
878 | break; | |
879 | } | |
34bbd704 ON |
880 | |
881 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
882 | return ret; |
883 | } | |
884 | ||
885 | /** | |
886 | * try_to_unmap_file - unmap file page using the object-based rmap method | |
887 | * @page: the page to unmap | |
43d8eac4 | 888 | * @migration: migration flag |
1da177e4 LT |
889 | * |
890 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
891 | * contained in the address_space struct it points to. | |
892 | * | |
893 | * This function is only called from try_to_unmap for object-based pages. | |
894 | */ | |
7352349a | 895 | static int try_to_unmap_file(struct page *page, int migration) |
1da177e4 LT |
896 | { |
897 | struct address_space *mapping = page->mapping; | |
898 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
899 | struct vm_area_struct *vma; | |
900 | struct prio_tree_iter iter; | |
901 | int ret = SWAP_AGAIN; | |
902 | unsigned long cursor; | |
903 | unsigned long max_nl_cursor = 0; | |
904 | unsigned long max_nl_size = 0; | |
905 | unsigned int mapcount; | |
906 | ||
907 | spin_lock(&mapping->i_mmap_lock); | |
908 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
7352349a | 909 | ret = try_to_unmap_one(page, vma, migration); |
1da177e4 LT |
910 | if (ret == SWAP_FAIL || !page_mapped(page)) |
911 | goto out; | |
912 | } | |
913 | ||
914 | if (list_empty(&mapping->i_mmap_nonlinear)) | |
915 | goto out; | |
916 | ||
917 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
918 | shared.vm_set.list) { | |
e6a1530d | 919 | if ((vma->vm_flags & VM_LOCKED) && !migration) |
1da177e4 LT |
920 | continue; |
921 | cursor = (unsigned long) vma->vm_private_data; | |
922 | if (cursor > max_nl_cursor) | |
923 | max_nl_cursor = cursor; | |
924 | cursor = vma->vm_end - vma->vm_start; | |
925 | if (cursor > max_nl_size) | |
926 | max_nl_size = cursor; | |
927 | } | |
928 | ||
929 | if (max_nl_size == 0) { /* any nonlinears locked or reserved */ | |
930 | ret = SWAP_FAIL; | |
931 | goto out; | |
932 | } | |
933 | ||
934 | /* | |
935 | * We don't try to search for this page in the nonlinear vmas, | |
936 | * and page_referenced wouldn't have found it anyway. Instead | |
937 | * just walk the nonlinear vmas trying to age and unmap some. | |
938 | * The mapcount of the page we came in with is irrelevant, | |
939 | * but even so use it as a guide to how hard we should try? | |
940 | */ | |
941 | mapcount = page_mapcount(page); | |
942 | if (!mapcount) | |
943 | goto out; | |
944 | cond_resched_lock(&mapping->i_mmap_lock); | |
945 | ||
946 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
947 | if (max_nl_cursor == 0) | |
948 | max_nl_cursor = CLUSTER_SIZE; | |
949 | ||
950 | do { | |
951 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
952 | shared.vm_set.list) { | |
e6a1530d | 953 | if ((vma->vm_flags & VM_LOCKED) && !migration) |
1da177e4 LT |
954 | continue; |
955 | cursor = (unsigned long) vma->vm_private_data; | |
839b9685 | 956 | while ( cursor < max_nl_cursor && |
1da177e4 LT |
957 | cursor < vma->vm_end - vma->vm_start) { |
958 | try_to_unmap_cluster(cursor, &mapcount, vma); | |
959 | cursor += CLUSTER_SIZE; | |
960 | vma->vm_private_data = (void *) cursor; | |
961 | if ((int)mapcount <= 0) | |
962 | goto out; | |
963 | } | |
964 | vma->vm_private_data = (void *) max_nl_cursor; | |
965 | } | |
966 | cond_resched_lock(&mapping->i_mmap_lock); | |
967 | max_nl_cursor += CLUSTER_SIZE; | |
968 | } while (max_nl_cursor <= max_nl_size); | |
969 | ||
970 | /* | |
971 | * Don't loop forever (perhaps all the remaining pages are | |
972 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
973 | * vmas, now forgetting on which ones it had fallen behind. | |
974 | */ | |
101d2be7 HD |
975 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
976 | vma->vm_private_data = NULL; | |
1da177e4 LT |
977 | out: |
978 | spin_unlock(&mapping->i_mmap_lock); | |
979 | return ret; | |
980 | } | |
981 | ||
982 | /** | |
983 | * try_to_unmap - try to remove all page table mappings to a page | |
984 | * @page: the page to get unmapped | |
43d8eac4 | 985 | * @migration: migration flag |
1da177e4 LT |
986 | * |
987 | * Tries to remove all the page table entries which are mapping this | |
988 | * page, used in the pageout path. Caller must hold the page lock. | |
989 | * Return values are: | |
990 | * | |
991 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
992 | * SWAP_AGAIN - we missed a mapping, try again later | |
993 | * SWAP_FAIL - the page is unswappable | |
994 | */ | |
7352349a | 995 | int try_to_unmap(struct page *page, int migration) |
1da177e4 LT |
996 | { |
997 | int ret; | |
998 | ||
1da177e4 LT |
999 | BUG_ON(!PageLocked(page)); |
1000 | ||
1001 | if (PageAnon(page)) | |
7352349a | 1002 | ret = try_to_unmap_anon(page, migration); |
1da177e4 | 1003 | else |
7352349a | 1004 | ret = try_to_unmap_file(page, migration); |
1da177e4 LT |
1005 | |
1006 | if (!page_mapped(page)) | |
1007 | ret = SWAP_SUCCESS; | |
1008 | return ret; | |
1009 | } | |
81b4082d | 1010 |