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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> |
64cdd548 | 53 | #include <linux/migrate.h> |
1da177e4 LT |
54 | |
55 | #include <asm/tlbflush.h> | |
56 | ||
b291f000 NP |
57 | #include "internal.h" |
58 | ||
fdd2e5f8 AB |
59 | static struct kmem_cache *anon_vma_cachep; |
60 | ||
61 | static inline struct anon_vma *anon_vma_alloc(void) | |
62 | { | |
63 | return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); | |
64 | } | |
65 | ||
66 | static inline void anon_vma_free(struct anon_vma *anon_vma) | |
67 | { | |
68 | kmem_cache_free(anon_vma_cachep, anon_vma); | |
69 | } | |
1da177e4 | 70 | |
d9d332e0 LT |
71 | /** |
72 | * anon_vma_prepare - attach an anon_vma to a memory region | |
73 | * @vma: the memory region in question | |
74 | * | |
75 | * This makes sure the memory mapping described by 'vma' has | |
76 | * an 'anon_vma' attached to it, so that we can associate the | |
77 | * anonymous pages mapped into it with that anon_vma. | |
78 | * | |
79 | * The common case will be that we already have one, but if | |
80 | * if not we either need to find an adjacent mapping that we | |
81 | * can re-use the anon_vma from (very common when the only | |
82 | * reason for splitting a vma has been mprotect()), or we | |
83 | * allocate a new one. | |
84 | * | |
85 | * Anon-vma allocations are very subtle, because we may have | |
86 | * optimistically looked up an anon_vma in page_lock_anon_vma() | |
87 | * and that may actually touch the spinlock even in the newly | |
88 | * allocated vma (it depends on RCU to make sure that the | |
89 | * anon_vma isn't actually destroyed). | |
90 | * | |
91 | * As a result, we need to do proper anon_vma locking even | |
92 | * for the new allocation. At the same time, we do not want | |
93 | * to do any locking for the common case of already having | |
94 | * an anon_vma. | |
95 | * | |
96 | * This must be called with the mmap_sem held for reading. | |
97 | */ | |
1da177e4 LT |
98 | int anon_vma_prepare(struct vm_area_struct *vma) |
99 | { | |
100 | struct anon_vma *anon_vma = vma->anon_vma; | |
101 | ||
102 | might_sleep(); | |
103 | if (unlikely(!anon_vma)) { | |
104 | struct mm_struct *mm = vma->vm_mm; | |
d9d332e0 | 105 | struct anon_vma *allocated; |
1da177e4 LT |
106 | |
107 | anon_vma = find_mergeable_anon_vma(vma); | |
d9d332e0 LT |
108 | allocated = NULL; |
109 | if (!anon_vma) { | |
1da177e4 LT |
110 | anon_vma = anon_vma_alloc(); |
111 | if (unlikely(!anon_vma)) | |
112 | return -ENOMEM; | |
113 | allocated = anon_vma; | |
1da177e4 | 114 | } |
d9d332e0 | 115 | spin_lock(&anon_vma->lock); |
1da177e4 LT |
116 | |
117 | /* page_table_lock to protect against threads */ | |
118 | spin_lock(&mm->page_table_lock); | |
119 | if (likely(!vma->anon_vma)) { | |
120 | vma->anon_vma = anon_vma; | |
0697212a | 121 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
122 | allocated = NULL; |
123 | } | |
124 | spin_unlock(&mm->page_table_lock); | |
125 | ||
d9d332e0 | 126 | spin_unlock(&anon_vma->lock); |
1da177e4 LT |
127 | if (unlikely(allocated)) |
128 | anon_vma_free(allocated); | |
129 | } | |
130 | return 0; | |
131 | } | |
132 | ||
133 | void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) | |
134 | { | |
135 | BUG_ON(vma->anon_vma != next->anon_vma); | |
136 | list_del(&next->anon_vma_node); | |
137 | } | |
138 | ||
139 | void __anon_vma_link(struct vm_area_struct *vma) | |
140 | { | |
141 | struct anon_vma *anon_vma = vma->anon_vma; | |
142 | ||
30acbaba | 143 | if (anon_vma) |
0697212a | 144 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
145 | } |
146 | ||
147 | void anon_vma_link(struct vm_area_struct *vma) | |
148 | { | |
149 | struct anon_vma *anon_vma = vma->anon_vma; | |
150 | ||
151 | if (anon_vma) { | |
152 | spin_lock(&anon_vma->lock); | |
0697212a | 153 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
154 | spin_unlock(&anon_vma->lock); |
155 | } | |
156 | } | |
157 | ||
158 | void anon_vma_unlink(struct vm_area_struct *vma) | |
159 | { | |
160 | struct anon_vma *anon_vma = vma->anon_vma; | |
161 | int empty; | |
162 | ||
163 | if (!anon_vma) | |
164 | return; | |
165 | ||
166 | spin_lock(&anon_vma->lock); | |
1da177e4 LT |
167 | list_del(&vma->anon_vma_node); |
168 | ||
169 | /* We must garbage collect the anon_vma if it's empty */ | |
170 | empty = list_empty(&anon_vma->head); | |
171 | spin_unlock(&anon_vma->lock); | |
172 | ||
173 | if (empty) | |
174 | anon_vma_free(anon_vma); | |
175 | } | |
176 | ||
51cc5068 | 177 | static void anon_vma_ctor(void *data) |
1da177e4 | 178 | { |
a35afb83 | 179 | struct anon_vma *anon_vma = data; |
1da177e4 | 180 | |
a35afb83 CL |
181 | spin_lock_init(&anon_vma->lock); |
182 | INIT_LIST_HEAD(&anon_vma->head); | |
1da177e4 LT |
183 | } |
184 | ||
185 | void __init anon_vma_init(void) | |
186 | { | |
187 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 188 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
1da177e4 LT |
189 | } |
190 | ||
191 | /* | |
192 | * Getting a lock on a stable anon_vma from a page off the LRU is | |
193 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. | |
194 | */ | |
af936a16 | 195 | struct anon_vma *page_lock_anon_vma(struct page *page) |
1da177e4 | 196 | { |
34bbd704 | 197 | struct anon_vma *anon_vma; |
1da177e4 LT |
198 | unsigned long anon_mapping; |
199 | ||
200 | rcu_read_lock(); | |
201 | anon_mapping = (unsigned long) page->mapping; | |
202 | if (!(anon_mapping & PAGE_MAPPING_ANON)) | |
203 | goto out; | |
204 | if (!page_mapped(page)) | |
205 | goto out; | |
206 | ||
207 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
208 | spin_lock(&anon_vma->lock); | |
34bbd704 | 209 | return anon_vma; |
1da177e4 LT |
210 | out: |
211 | rcu_read_unlock(); | |
34bbd704 ON |
212 | return NULL; |
213 | } | |
214 | ||
af936a16 | 215 | void page_unlock_anon_vma(struct anon_vma *anon_vma) |
34bbd704 ON |
216 | { |
217 | spin_unlock(&anon_vma->lock); | |
218 | rcu_read_unlock(); | |
1da177e4 LT |
219 | } |
220 | ||
221 | /* | |
3ad33b24 LS |
222 | * At what user virtual address is page expected in @vma? |
223 | * Returns virtual address or -EFAULT if page's index/offset is not | |
224 | * within the range mapped the @vma. | |
1da177e4 LT |
225 | */ |
226 | static inline unsigned long | |
227 | vma_address(struct page *page, struct vm_area_struct *vma) | |
228 | { | |
229 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
230 | unsigned long address; | |
231 | ||
232 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
233 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { | |
3ad33b24 | 234 | /* page should be within @vma mapping range */ |
1da177e4 LT |
235 | return -EFAULT; |
236 | } | |
237 | return address; | |
238 | } | |
239 | ||
240 | /* | |
241 | * At what user virtual address is page expected in vma? checking that the | |
ee498ed7 | 242 | * page matches the vma: currently only used on anon pages, by unuse_vma; |
1da177e4 LT |
243 | */ |
244 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
245 | { | |
246 | if (PageAnon(page)) { | |
247 | if ((void *)vma->anon_vma != | |
248 | (void *)page->mapping - PAGE_MAPPING_ANON) | |
249 | return -EFAULT; | |
250 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
251 | if (!vma->vm_file || |
252 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
253 | return -EFAULT; |
254 | } else | |
255 | return -EFAULT; | |
256 | return vma_address(page, vma); | |
257 | } | |
258 | ||
81b4082d ND |
259 | /* |
260 | * Check that @page is mapped at @address into @mm. | |
261 | * | |
479db0bf NP |
262 | * If @sync is false, page_check_address may perform a racy check to avoid |
263 | * the page table lock when the pte is not present (helpful when reclaiming | |
264 | * highly shared pages). | |
265 | * | |
b8072f09 | 266 | * On success returns with pte mapped and locked. |
81b4082d | 267 | */ |
ceffc078 | 268 | pte_t *page_check_address(struct page *page, struct mm_struct *mm, |
479db0bf | 269 | unsigned long address, spinlock_t **ptlp, int sync) |
81b4082d ND |
270 | { |
271 | pgd_t *pgd; | |
272 | pud_t *pud; | |
273 | pmd_t *pmd; | |
274 | pte_t *pte; | |
c0718806 | 275 | spinlock_t *ptl; |
81b4082d | 276 | |
81b4082d | 277 | pgd = pgd_offset(mm, address); |
c0718806 HD |
278 | if (!pgd_present(*pgd)) |
279 | return NULL; | |
280 | ||
281 | pud = pud_offset(pgd, address); | |
282 | if (!pud_present(*pud)) | |
283 | return NULL; | |
284 | ||
285 | pmd = pmd_offset(pud, address); | |
286 | if (!pmd_present(*pmd)) | |
287 | return NULL; | |
288 | ||
289 | pte = pte_offset_map(pmd, address); | |
290 | /* Make a quick check before getting the lock */ | |
479db0bf | 291 | if (!sync && !pte_present(*pte)) { |
c0718806 HD |
292 | pte_unmap(pte); |
293 | return NULL; | |
294 | } | |
295 | ||
4c21e2f2 | 296 | ptl = pte_lockptr(mm, pmd); |
c0718806 HD |
297 | spin_lock(ptl); |
298 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
299 | *ptlp = ptl; | |
300 | return pte; | |
81b4082d | 301 | } |
c0718806 HD |
302 | pte_unmap_unlock(pte, ptl); |
303 | return NULL; | |
81b4082d ND |
304 | } |
305 | ||
b291f000 NP |
306 | /** |
307 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
308 | * @page: the page to test | |
309 | * @vma: the VMA to test | |
310 | * | |
311 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
312 | * if the page is not mapped into the page tables of this VMA. Only | |
313 | * valid for normal file or anonymous VMAs. | |
314 | */ | |
315 | static int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) | |
316 | { | |
317 | unsigned long address; | |
318 | pte_t *pte; | |
319 | spinlock_t *ptl; | |
320 | ||
321 | address = vma_address(page, vma); | |
322 | if (address == -EFAULT) /* out of vma range */ | |
323 | return 0; | |
324 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); | |
325 | if (!pte) /* the page is not in this mm */ | |
326 | return 0; | |
327 | pte_unmap_unlock(pte, ptl); | |
328 | ||
329 | return 1; | |
330 | } | |
331 | ||
1da177e4 LT |
332 | /* |
333 | * Subfunctions of page_referenced: page_referenced_one called | |
334 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
335 | */ | |
336 | static int page_referenced_one(struct page *page, | |
f7b7fd8f | 337 | struct vm_area_struct *vma, unsigned int *mapcount) |
1da177e4 LT |
338 | { |
339 | struct mm_struct *mm = vma->vm_mm; | |
340 | unsigned long address; | |
1da177e4 | 341 | pte_t *pte; |
c0718806 | 342 | spinlock_t *ptl; |
1da177e4 LT |
343 | int referenced = 0; |
344 | ||
1da177e4 LT |
345 | address = vma_address(page, vma); |
346 | if (address == -EFAULT) | |
347 | goto out; | |
348 | ||
479db0bf | 349 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 HD |
350 | if (!pte) |
351 | goto out; | |
1da177e4 | 352 | |
b291f000 NP |
353 | /* |
354 | * Don't want to elevate referenced for mlocked page that gets this far, | |
355 | * in order that it progresses to try_to_unmap and is moved to the | |
356 | * unevictable list. | |
357 | */ | |
5a9bbdcd | 358 | if (vma->vm_flags & VM_LOCKED) { |
5a9bbdcd | 359 | *mapcount = 1; /* break early from loop */ |
b291f000 NP |
360 | goto out_unmap; |
361 | } | |
362 | ||
363 | if (ptep_clear_flush_young_notify(vma, address, pte)) | |
c0718806 | 364 | referenced++; |
1da177e4 | 365 | |
c0718806 HD |
366 | /* Pretend the page is referenced if the task has the |
367 | swap token and is in the middle of a page fault. */ | |
f7b7fd8f | 368 | if (mm != current->mm && has_swap_token(mm) && |
c0718806 HD |
369 | rwsem_is_locked(&mm->mmap_sem)) |
370 | referenced++; | |
371 | ||
b291f000 | 372 | out_unmap: |
c0718806 HD |
373 | (*mapcount)--; |
374 | pte_unmap_unlock(pte, ptl); | |
1da177e4 LT |
375 | out: |
376 | return referenced; | |
377 | } | |
378 | ||
bed7161a BS |
379 | static int page_referenced_anon(struct page *page, |
380 | struct mem_cgroup *mem_cont) | |
1da177e4 LT |
381 | { |
382 | unsigned int mapcount; | |
383 | struct anon_vma *anon_vma; | |
384 | struct vm_area_struct *vma; | |
385 | int referenced = 0; | |
386 | ||
387 | anon_vma = page_lock_anon_vma(page); | |
388 | if (!anon_vma) | |
389 | return referenced; | |
390 | ||
391 | mapcount = page_mapcount(page); | |
392 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
bed7161a BS |
393 | /* |
394 | * If we are reclaiming on behalf of a cgroup, skip | |
395 | * counting on behalf of references from different | |
396 | * cgroups | |
397 | */ | |
bd845e38 | 398 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 399 | continue; |
f7b7fd8f | 400 | referenced += page_referenced_one(page, vma, &mapcount); |
1da177e4 LT |
401 | if (!mapcount) |
402 | break; | |
403 | } | |
34bbd704 ON |
404 | |
405 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
406 | return referenced; |
407 | } | |
408 | ||
409 | /** | |
410 | * page_referenced_file - referenced check for object-based rmap | |
411 | * @page: the page we're checking references on. | |
43d8eac4 | 412 | * @mem_cont: target memory controller |
1da177e4 LT |
413 | * |
414 | * For an object-based mapped page, find all the places it is mapped and | |
415 | * check/clear the referenced flag. This is done by following the page->mapping | |
416 | * pointer, then walking the chain of vmas it holds. It returns the number | |
417 | * of references it found. | |
418 | * | |
419 | * This function is only called from page_referenced for object-based pages. | |
420 | */ | |
bed7161a BS |
421 | static int page_referenced_file(struct page *page, |
422 | struct mem_cgroup *mem_cont) | |
1da177e4 LT |
423 | { |
424 | unsigned int mapcount; | |
425 | struct address_space *mapping = page->mapping; | |
426 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
427 | struct vm_area_struct *vma; | |
428 | struct prio_tree_iter iter; | |
429 | int referenced = 0; | |
430 | ||
431 | /* | |
432 | * The caller's checks on page->mapping and !PageAnon have made | |
433 | * sure that this is a file page: the check for page->mapping | |
434 | * excludes the case just before it gets set on an anon page. | |
435 | */ | |
436 | BUG_ON(PageAnon(page)); | |
437 | ||
438 | /* | |
439 | * The page lock not only makes sure that page->mapping cannot | |
440 | * suddenly be NULLified by truncation, it makes sure that the | |
441 | * structure at mapping cannot be freed and reused yet, | |
442 | * so we can safely take mapping->i_mmap_lock. | |
443 | */ | |
444 | BUG_ON(!PageLocked(page)); | |
445 | ||
446 | spin_lock(&mapping->i_mmap_lock); | |
447 | ||
448 | /* | |
449 | * i_mmap_lock does not stabilize mapcount at all, but mapcount | |
450 | * is more likely to be accurate if we note it after spinning. | |
451 | */ | |
452 | mapcount = page_mapcount(page); | |
453 | ||
454 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
bed7161a BS |
455 | /* |
456 | * If we are reclaiming on behalf of a cgroup, skip | |
457 | * counting on behalf of references from different | |
458 | * cgroups | |
459 | */ | |
bd845e38 | 460 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 461 | continue; |
f7b7fd8f | 462 | referenced += page_referenced_one(page, vma, &mapcount); |
1da177e4 LT |
463 | if (!mapcount) |
464 | break; | |
465 | } | |
466 | ||
467 | spin_unlock(&mapping->i_mmap_lock); | |
468 | return referenced; | |
469 | } | |
470 | ||
471 | /** | |
472 | * page_referenced - test if the page was referenced | |
473 | * @page: the page to test | |
474 | * @is_locked: caller holds lock on the page | |
43d8eac4 | 475 | * @mem_cont: target memory controller |
1da177e4 LT |
476 | * |
477 | * Quick test_and_clear_referenced for all mappings to a page, | |
478 | * returns the number of ptes which referenced the page. | |
479 | */ | |
bed7161a BS |
480 | int page_referenced(struct page *page, int is_locked, |
481 | struct mem_cgroup *mem_cont) | |
1da177e4 LT |
482 | { |
483 | int referenced = 0; | |
484 | ||
1da177e4 LT |
485 | if (TestClearPageReferenced(page)) |
486 | referenced++; | |
487 | ||
488 | if (page_mapped(page) && page->mapping) { | |
489 | if (PageAnon(page)) | |
bed7161a | 490 | referenced += page_referenced_anon(page, mem_cont); |
1da177e4 | 491 | else if (is_locked) |
bed7161a | 492 | referenced += page_referenced_file(page, mem_cont); |
529ae9aa | 493 | else if (!trylock_page(page)) |
1da177e4 LT |
494 | referenced++; |
495 | else { | |
496 | if (page->mapping) | |
bed7161a BS |
497 | referenced += |
498 | page_referenced_file(page, mem_cont); | |
1da177e4 LT |
499 | unlock_page(page); |
500 | } | |
501 | } | |
5b7baf05 CB |
502 | |
503 | if (page_test_and_clear_young(page)) | |
504 | referenced++; | |
505 | ||
1da177e4 LT |
506 | return referenced; |
507 | } | |
508 | ||
d08b3851 PZ |
509 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) |
510 | { | |
511 | struct mm_struct *mm = vma->vm_mm; | |
512 | unsigned long address; | |
c2fda5fe | 513 | pte_t *pte; |
d08b3851 PZ |
514 | spinlock_t *ptl; |
515 | int ret = 0; | |
516 | ||
517 | address = vma_address(page, vma); | |
518 | if (address == -EFAULT) | |
519 | goto out; | |
520 | ||
479db0bf | 521 | pte = page_check_address(page, mm, address, &ptl, 1); |
d08b3851 PZ |
522 | if (!pte) |
523 | goto out; | |
524 | ||
c2fda5fe PZ |
525 | if (pte_dirty(*pte) || pte_write(*pte)) { |
526 | pte_t entry; | |
d08b3851 | 527 | |
c2fda5fe | 528 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 529 | entry = ptep_clear_flush_notify(vma, address, pte); |
c2fda5fe PZ |
530 | entry = pte_wrprotect(entry); |
531 | entry = pte_mkclean(entry); | |
d6e88e67 | 532 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
533 | ret = 1; |
534 | } | |
d08b3851 | 535 | |
d08b3851 PZ |
536 | pte_unmap_unlock(pte, ptl); |
537 | out: | |
538 | return ret; | |
539 | } | |
540 | ||
541 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
542 | { | |
543 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
544 | struct vm_area_struct *vma; | |
545 | struct prio_tree_iter iter; | |
546 | int ret = 0; | |
547 | ||
548 | BUG_ON(PageAnon(page)); | |
549 | ||
550 | spin_lock(&mapping->i_mmap_lock); | |
551 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
552 | if (vma->vm_flags & VM_SHARED) | |
553 | ret += page_mkclean_one(page, vma); | |
554 | } | |
555 | spin_unlock(&mapping->i_mmap_lock); | |
556 | return ret; | |
557 | } | |
558 | ||
559 | int page_mkclean(struct page *page) | |
560 | { | |
561 | int ret = 0; | |
562 | ||
563 | BUG_ON(!PageLocked(page)); | |
564 | ||
565 | if (page_mapped(page)) { | |
566 | struct address_space *mapping = page_mapping(page); | |
ce7e9fae | 567 | if (mapping) { |
d08b3851 | 568 | ret = page_mkclean_file(mapping, page); |
ce7e9fae CB |
569 | if (page_test_dirty(page)) { |
570 | page_clear_dirty(page); | |
571 | ret = 1; | |
572 | } | |
6c210482 | 573 | } |
d08b3851 PZ |
574 | } |
575 | ||
576 | return ret; | |
577 | } | |
60b59bea | 578 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 579 | |
9617d95e | 580 | /** |
43d8eac4 | 581 | * __page_set_anon_rmap - setup new anonymous rmap |
9617d95e NP |
582 | * @page: the page to add the mapping to |
583 | * @vma: the vm area in which the mapping is added | |
584 | * @address: the user virtual address mapped | |
585 | */ | |
586 | static void __page_set_anon_rmap(struct page *page, | |
587 | struct vm_area_struct *vma, unsigned long address) | |
588 | { | |
589 | struct anon_vma *anon_vma = vma->anon_vma; | |
590 | ||
591 | BUG_ON(!anon_vma); | |
592 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
593 | page->mapping = (struct address_space *) anon_vma; | |
594 | ||
595 | page->index = linear_page_index(vma, address); | |
596 | ||
a74609fa NP |
597 | /* |
598 | * nr_mapped state can be updated without turning off | |
599 | * interrupts because it is not modified via interrupt. | |
600 | */ | |
f3dbd344 | 601 | __inc_zone_page_state(page, NR_ANON_PAGES); |
9617d95e NP |
602 | } |
603 | ||
c97a9e10 | 604 | /** |
43d8eac4 | 605 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
c97a9e10 NP |
606 | * @page: the page to add the mapping to |
607 | * @vma: the vm area in which the mapping is added | |
608 | * @address: the user virtual address mapped | |
609 | */ | |
610 | static void __page_check_anon_rmap(struct page *page, | |
611 | struct vm_area_struct *vma, unsigned long address) | |
612 | { | |
613 | #ifdef CONFIG_DEBUG_VM | |
614 | /* | |
615 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
616 | * be set up correctly at this point. | |
617 | * | |
618 | * We have exclusion against page_add_anon_rmap because the caller | |
619 | * always holds the page locked, except if called from page_dup_rmap, | |
620 | * in which case the page is already known to be setup. | |
621 | * | |
622 | * We have exclusion against page_add_new_anon_rmap because those pages | |
623 | * are initially only visible via the pagetables, and the pte is locked | |
624 | * over the call to page_add_new_anon_rmap. | |
625 | */ | |
626 | struct anon_vma *anon_vma = vma->anon_vma; | |
627 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
628 | BUG_ON(page->mapping != (struct address_space *)anon_vma); | |
629 | BUG_ON(page->index != linear_page_index(vma, address)); | |
630 | #endif | |
631 | } | |
632 | ||
1da177e4 LT |
633 | /** |
634 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
635 | * @page: the page to add the mapping to | |
636 | * @vma: the vm area in which the mapping is added | |
637 | * @address: the user virtual address mapped | |
638 | * | |
c97a9e10 | 639 | * The caller needs to hold the pte lock and the page must be locked. |
1da177e4 LT |
640 | */ |
641 | void page_add_anon_rmap(struct page *page, | |
642 | struct vm_area_struct *vma, unsigned long address) | |
643 | { | |
c97a9e10 NP |
644 | VM_BUG_ON(!PageLocked(page)); |
645 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
9617d95e NP |
646 | if (atomic_inc_and_test(&page->_mapcount)) |
647 | __page_set_anon_rmap(page, vma, address); | |
69029cd5 | 648 | else |
c97a9e10 | 649 | __page_check_anon_rmap(page, vma, address); |
1da177e4 LT |
650 | } |
651 | ||
43d8eac4 | 652 | /** |
9617d95e NP |
653 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
654 | * @page: the page to add the mapping to | |
655 | * @vma: the vm area in which the mapping is added | |
656 | * @address: the user virtual address mapped | |
657 | * | |
658 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
659 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 660 | * Page does not have to be locked. |
9617d95e NP |
661 | */ |
662 | void page_add_new_anon_rmap(struct page *page, | |
663 | struct vm_area_struct *vma, unsigned long address) | |
664 | { | |
c97a9e10 | 665 | BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
9617d95e NP |
666 | atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ |
667 | __page_set_anon_rmap(page, vma, address); | |
668 | } | |
669 | ||
1da177e4 LT |
670 | /** |
671 | * page_add_file_rmap - add pte mapping to a file page | |
672 | * @page: the page to add the mapping to | |
673 | * | |
b8072f09 | 674 | * The caller needs to hold the pte lock. |
1da177e4 LT |
675 | */ |
676 | void page_add_file_rmap(struct page *page) | |
677 | { | |
1da177e4 | 678 | if (atomic_inc_and_test(&page->_mapcount)) |
65ba55f5 | 679 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
1da177e4 LT |
680 | } |
681 | ||
c97a9e10 NP |
682 | #ifdef CONFIG_DEBUG_VM |
683 | /** | |
684 | * page_dup_rmap - duplicate pte mapping to a page | |
685 | * @page: the page to add the mapping to | |
43d8eac4 RD |
686 | * @vma: the vm area being duplicated |
687 | * @address: the user virtual address mapped | |
c97a9e10 NP |
688 | * |
689 | * For copy_page_range only: minimal extract from page_add_file_rmap / | |
690 | * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's | |
691 | * quicker. | |
692 | * | |
693 | * The caller needs to hold the pte lock. | |
694 | */ | |
695 | void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) | |
696 | { | |
697 | BUG_ON(page_mapcount(page) == 0); | |
698 | if (PageAnon(page)) | |
699 | __page_check_anon_rmap(page, vma, address); | |
700 | atomic_inc(&page->_mapcount); | |
701 | } | |
702 | #endif | |
703 | ||
1da177e4 LT |
704 | /** |
705 | * page_remove_rmap - take down pte mapping from a page | |
706 | * @page: page to remove mapping from | |
43d8eac4 | 707 | * @vma: the vm area in which the mapping is removed |
1da177e4 | 708 | * |
b8072f09 | 709 | * The caller needs to hold the pte lock. |
1da177e4 | 710 | */ |
7de6b805 | 711 | void page_remove_rmap(struct page *page, struct vm_area_struct *vma) |
1da177e4 | 712 | { |
1da177e4 | 713 | if (atomic_add_negative(-1, &page->_mapcount)) { |
b7ab795b | 714 | if (unlikely(page_mapcount(page) < 0)) { |
ef2bf0dc | 715 | printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); |
7de6b805 | 716 | printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(page)); |
ef2bf0dc DJ |
717 | printk (KERN_EMERG " page->flags = %lx\n", page->flags); |
718 | printk (KERN_EMERG " page->count = %x\n", page_count(page)); | |
719 | printk (KERN_EMERG " page->mapping = %p\n", page->mapping); | |
7de6b805 | 720 | print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops); |
54cb8821 | 721 | if (vma->vm_ops) { |
54cb8821 NP |
722 | print_symbol (KERN_EMERG " vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault); |
723 | } | |
7de6b805 NP |
724 | if (vma->vm_file && vma->vm_file->f_op) |
725 | print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap); | |
b16bc64d | 726 | BUG(); |
ef2bf0dc | 727 | } |
b16bc64d | 728 | |
1da177e4 | 729 | /* |
16f8c5b2 HD |
730 | * Now that the last pte has gone, s390 must transfer dirty |
731 | * flag from storage key to struct page. We can usually skip | |
732 | * this if the page is anon, so about to be freed; but perhaps | |
733 | * not if it's in swapcache - there might be another pte slot | |
734 | * containing the swap entry, but page not yet written to swap. | |
1da177e4 | 735 | */ |
a4b526b3 MS |
736 | if ((!PageAnon(page) || PageSwapCache(page)) && |
737 | page_test_dirty(page)) { | |
6c210482 | 738 | page_clear_dirty(page); |
1da177e4 | 739 | set_page_dirty(page); |
6c210482 | 740 | } |
5b4e655e KH |
741 | if (PageAnon(page)) |
742 | mem_cgroup_uncharge_page(page); | |
f3dbd344 | 743 | __dec_zone_page_state(page, |
16f8c5b2 HD |
744 | PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); |
745 | /* | |
746 | * It would be tidy to reset the PageAnon mapping here, | |
747 | * but that might overwrite a racing page_add_anon_rmap | |
748 | * which increments mapcount after us but sets mapping | |
749 | * before us: so leave the reset to free_hot_cold_page, | |
750 | * and remember that it's only reliable while mapped. | |
751 | * Leaving it set also helps swapoff to reinstate ptes | |
752 | * faster for those pages still in swapcache. | |
753 | */ | |
1da177e4 LT |
754 | } |
755 | } | |
756 | ||
757 | /* | |
758 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
759 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. | |
760 | */ | |
a48d07af | 761 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
7352349a | 762 | int migration) |
1da177e4 LT |
763 | { |
764 | struct mm_struct *mm = vma->vm_mm; | |
765 | unsigned long address; | |
1da177e4 LT |
766 | pte_t *pte; |
767 | pte_t pteval; | |
c0718806 | 768 | spinlock_t *ptl; |
1da177e4 LT |
769 | int ret = SWAP_AGAIN; |
770 | ||
1da177e4 LT |
771 | address = vma_address(page, vma); |
772 | if (address == -EFAULT) | |
773 | goto out; | |
774 | ||
479db0bf | 775 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 | 776 | if (!pte) |
81b4082d | 777 | goto out; |
1da177e4 LT |
778 | |
779 | /* | |
780 | * If the page is mlock()d, we cannot swap it out. | |
781 | * If it's recently referenced (perhaps page_referenced | |
782 | * skipped over this mm) then we should reactivate it. | |
783 | */ | |
b291f000 NP |
784 | if (!migration) { |
785 | if (vma->vm_flags & VM_LOCKED) { | |
786 | ret = SWAP_MLOCK; | |
787 | goto out_unmap; | |
788 | } | |
789 | if (ptep_clear_flush_young_notify(vma, address, pte)) { | |
790 | ret = SWAP_FAIL; | |
791 | goto out_unmap; | |
792 | } | |
793 | } | |
1da177e4 | 794 | |
1da177e4 LT |
795 | /* Nuke the page table entry. */ |
796 | flush_cache_page(vma, address, page_to_pfn(page)); | |
cddb8a5c | 797 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
798 | |
799 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
800 | if (pte_dirty(pteval)) | |
801 | set_page_dirty(page); | |
802 | ||
365e9c87 HD |
803 | /* Update high watermark before we lower rss */ |
804 | update_hiwater_rss(mm); | |
805 | ||
1da177e4 | 806 | if (PageAnon(page)) { |
4c21e2f2 | 807 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
808 | |
809 | if (PageSwapCache(page)) { | |
810 | /* | |
811 | * Store the swap location in the pte. | |
812 | * See handle_pte_fault() ... | |
813 | */ | |
814 | swap_duplicate(entry); | |
815 | if (list_empty(&mm->mmlist)) { | |
816 | spin_lock(&mmlist_lock); | |
817 | if (list_empty(&mm->mmlist)) | |
818 | list_add(&mm->mmlist, &init_mm.mmlist); | |
819 | spin_unlock(&mmlist_lock); | |
820 | } | |
442c9137 | 821 | dec_mm_counter(mm, anon_rss); |
64cdd548 | 822 | } else if (PAGE_MIGRATION) { |
0697212a CL |
823 | /* |
824 | * Store the pfn of the page in a special migration | |
825 | * pte. do_swap_page() will wait until the migration | |
826 | * pte is removed and then restart fault handling. | |
827 | */ | |
828 | BUG_ON(!migration); | |
829 | entry = make_migration_entry(page, pte_write(pteval)); | |
1da177e4 LT |
830 | } |
831 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
832 | BUG_ON(pte_file(*pte)); | |
64cdd548 | 833 | } else if (PAGE_MIGRATION && migration) { |
04e62a29 CL |
834 | /* Establish migration entry for a file page */ |
835 | swp_entry_t entry; | |
836 | entry = make_migration_entry(page, pte_write(pteval)); | |
837 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
838 | } else | |
4294621f | 839 | dec_mm_counter(mm, file_rss); |
1da177e4 | 840 | |
04e62a29 | 841 | |
7de6b805 | 842 | page_remove_rmap(page, vma); |
1da177e4 LT |
843 | page_cache_release(page); |
844 | ||
845 | out_unmap: | |
c0718806 | 846 | pte_unmap_unlock(pte, ptl); |
1da177e4 LT |
847 | out: |
848 | return ret; | |
849 | } | |
850 | ||
851 | /* | |
852 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
853 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
854 | * Consequently, given a particular page and its ->index, we cannot locate the | |
855 | * ptes which are mapping that page without an exhaustive linear search. | |
856 | * | |
857 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
858 | * maps the file to which the target page belongs. The ->vm_private_data field | |
859 | * holds the current cursor into that scan. Successive searches will circulate | |
860 | * around the vma's virtual address space. | |
861 | * | |
862 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
863 | * more scanning pressure is placed against them as well. Eventually pages | |
864 | * will become fully unmapped and are eligible for eviction. | |
865 | * | |
866 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
867 | * there there won't be many ptes located within the scan cluster. In this case | |
868 | * maybe we could scan further - to the end of the pte page, perhaps. | |
b291f000 NP |
869 | * |
870 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can | |
871 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, | |
872 | * rather than unmapping them. If we encounter the "check_page" that vmscan is | |
873 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. | |
1da177e4 LT |
874 | */ |
875 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
876 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
877 | ||
b291f000 NP |
878 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
879 | struct vm_area_struct *vma, struct page *check_page) | |
1da177e4 LT |
880 | { |
881 | struct mm_struct *mm = vma->vm_mm; | |
882 | pgd_t *pgd; | |
883 | pud_t *pud; | |
884 | pmd_t *pmd; | |
c0718806 | 885 | pte_t *pte; |
1da177e4 | 886 | pte_t pteval; |
c0718806 | 887 | spinlock_t *ptl; |
1da177e4 LT |
888 | struct page *page; |
889 | unsigned long address; | |
890 | unsigned long end; | |
b291f000 NP |
891 | int ret = SWAP_AGAIN; |
892 | int locked_vma = 0; | |
1da177e4 | 893 | |
1da177e4 LT |
894 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
895 | end = address + CLUSTER_SIZE; | |
896 | if (address < vma->vm_start) | |
897 | address = vma->vm_start; | |
898 | if (end > vma->vm_end) | |
899 | end = vma->vm_end; | |
900 | ||
901 | pgd = pgd_offset(mm, address); | |
902 | if (!pgd_present(*pgd)) | |
b291f000 | 903 | return ret; |
1da177e4 LT |
904 | |
905 | pud = pud_offset(pgd, address); | |
906 | if (!pud_present(*pud)) | |
b291f000 | 907 | return ret; |
1da177e4 LT |
908 | |
909 | pmd = pmd_offset(pud, address); | |
910 | if (!pmd_present(*pmd)) | |
b291f000 NP |
911 | return ret; |
912 | ||
913 | /* | |
914 | * MLOCK_PAGES => feature is configured. | |
915 | * if we can acquire the mmap_sem for read, and vma is VM_LOCKED, | |
916 | * keep the sem while scanning the cluster for mlocking pages. | |
917 | */ | |
918 | if (MLOCK_PAGES && down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
919 | locked_vma = (vma->vm_flags & VM_LOCKED); | |
920 | if (!locked_vma) | |
921 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ | |
922 | } | |
c0718806 HD |
923 | |
924 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 925 | |
365e9c87 HD |
926 | /* Update high watermark before we lower rss */ |
927 | update_hiwater_rss(mm); | |
928 | ||
c0718806 | 929 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
930 | if (!pte_present(*pte)) |
931 | continue; | |
6aab341e LT |
932 | page = vm_normal_page(vma, address, *pte); |
933 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 | 934 | |
b291f000 NP |
935 | if (locked_vma) { |
936 | mlock_vma_page(page); /* no-op if already mlocked */ | |
937 | if (page == check_page) | |
938 | ret = SWAP_MLOCK; | |
939 | continue; /* don't unmap */ | |
940 | } | |
941 | ||
cddb8a5c | 942 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1da177e4 LT |
943 | continue; |
944 | ||
945 | /* Nuke the page table entry. */ | |
eca35133 | 946 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 947 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
948 | |
949 | /* If nonlinear, store the file page offset in the pte. */ | |
950 | if (page->index != linear_page_index(vma, address)) | |
951 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
952 | ||
953 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
954 | if (pte_dirty(pteval)) | |
955 | set_page_dirty(page); | |
956 | ||
7de6b805 | 957 | page_remove_rmap(page, vma); |
1da177e4 | 958 | page_cache_release(page); |
4294621f | 959 | dec_mm_counter(mm, file_rss); |
1da177e4 LT |
960 | (*mapcount)--; |
961 | } | |
c0718806 | 962 | pte_unmap_unlock(pte - 1, ptl); |
b291f000 NP |
963 | if (locked_vma) |
964 | up_read(&vma->vm_mm->mmap_sem); | |
965 | return ret; | |
1da177e4 LT |
966 | } |
967 | ||
b291f000 NP |
968 | /* |
969 | * common handling for pages mapped in VM_LOCKED vmas | |
970 | */ | |
971 | static int try_to_mlock_page(struct page *page, struct vm_area_struct *vma) | |
972 | { | |
973 | int mlocked = 0; | |
974 | ||
975 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
976 | if (vma->vm_flags & VM_LOCKED) { | |
977 | mlock_vma_page(page); | |
978 | mlocked++; /* really mlocked the page */ | |
979 | } | |
980 | up_read(&vma->vm_mm->mmap_sem); | |
981 | } | |
982 | return mlocked; | |
983 | } | |
984 | ||
985 | /** | |
986 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based | |
987 | * rmap method | |
988 | * @page: the page to unmap/unlock | |
989 | * @unlock: request for unlock rather than unmap [unlikely] | |
990 | * @migration: unmapping for migration - ignored if @unlock | |
991 | * | |
992 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
993 | * contained in the anon_vma struct it points to. | |
994 | * | |
995 | * This function is only called from try_to_unmap/try_to_munlock for | |
996 | * anonymous pages. | |
997 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
998 | * where the page was found will be held for write. So, we won't recheck | |
999 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1000 | * 'LOCKED. | |
1001 | */ | |
1002 | static int try_to_unmap_anon(struct page *page, int unlock, int migration) | |
1da177e4 LT |
1003 | { |
1004 | struct anon_vma *anon_vma; | |
1005 | struct vm_area_struct *vma; | |
b291f000 | 1006 | unsigned int mlocked = 0; |
1da177e4 LT |
1007 | int ret = SWAP_AGAIN; |
1008 | ||
b291f000 NP |
1009 | if (MLOCK_PAGES && unlikely(unlock)) |
1010 | ret = SWAP_SUCCESS; /* default for try_to_munlock() */ | |
1011 | ||
1da177e4 LT |
1012 | anon_vma = page_lock_anon_vma(page); |
1013 | if (!anon_vma) | |
1014 | return ret; | |
1015 | ||
1016 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
b291f000 NP |
1017 | if (MLOCK_PAGES && unlikely(unlock)) { |
1018 | if (!((vma->vm_flags & VM_LOCKED) && | |
1019 | page_mapped_in_vma(page, vma))) | |
1020 | continue; /* must visit all unlocked vmas */ | |
1021 | ret = SWAP_MLOCK; /* saw at least one mlocked vma */ | |
1022 | } else { | |
1023 | ret = try_to_unmap_one(page, vma, migration); | |
1024 | if (ret == SWAP_FAIL || !page_mapped(page)) | |
1025 | break; | |
1026 | } | |
1027 | if (ret == SWAP_MLOCK) { | |
1028 | mlocked = try_to_mlock_page(page, vma); | |
1029 | if (mlocked) | |
1030 | break; /* stop if actually mlocked page */ | |
1031 | } | |
1da177e4 | 1032 | } |
34bbd704 ON |
1033 | |
1034 | page_unlock_anon_vma(anon_vma); | |
b291f000 NP |
1035 | |
1036 | if (mlocked) | |
1037 | ret = SWAP_MLOCK; /* actually mlocked the page */ | |
1038 | else if (ret == SWAP_MLOCK) | |
1039 | ret = SWAP_AGAIN; /* saw VM_LOCKED vma */ | |
1040 | ||
1da177e4 LT |
1041 | return ret; |
1042 | } | |
1043 | ||
1044 | /** | |
b291f000 NP |
1045 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
1046 | * @page: the page to unmap/unlock | |
1047 | * @unlock: request for unlock rather than unmap [unlikely] | |
1048 | * @migration: unmapping for migration - ignored if @unlock | |
1da177e4 LT |
1049 | * |
1050 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1051 | * contained in the address_space struct it points to. | |
1052 | * | |
b291f000 NP |
1053 | * This function is only called from try_to_unmap/try_to_munlock for |
1054 | * object-based pages. | |
1055 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1056 | * where the page was found will be held for write. So, we won't recheck | |
1057 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1058 | * 'LOCKED. | |
1da177e4 | 1059 | */ |
b291f000 | 1060 | static int try_to_unmap_file(struct page *page, int unlock, int migration) |
1da177e4 LT |
1061 | { |
1062 | struct address_space *mapping = page->mapping; | |
1063 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1064 | struct vm_area_struct *vma; | |
1065 | struct prio_tree_iter iter; | |
1066 | int ret = SWAP_AGAIN; | |
1067 | unsigned long cursor; | |
1068 | unsigned long max_nl_cursor = 0; | |
1069 | unsigned long max_nl_size = 0; | |
1070 | unsigned int mapcount; | |
b291f000 NP |
1071 | unsigned int mlocked = 0; |
1072 | ||
1073 | if (MLOCK_PAGES && unlikely(unlock)) | |
1074 | ret = SWAP_SUCCESS; /* default for try_to_munlock() */ | |
1da177e4 LT |
1075 | |
1076 | spin_lock(&mapping->i_mmap_lock); | |
1077 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
b291f000 NP |
1078 | if (MLOCK_PAGES && unlikely(unlock)) { |
1079 | if (!(vma->vm_flags & VM_LOCKED)) | |
1080 | continue; /* must visit all vmas */ | |
1081 | ret = SWAP_MLOCK; | |
1082 | } else { | |
1083 | ret = try_to_unmap_one(page, vma, migration); | |
1084 | if (ret == SWAP_FAIL || !page_mapped(page)) | |
1085 | goto out; | |
1086 | } | |
1087 | if (ret == SWAP_MLOCK) { | |
1088 | mlocked = try_to_mlock_page(page, vma); | |
1089 | if (mlocked) | |
1090 | break; /* stop if actually mlocked page */ | |
1091 | } | |
1da177e4 LT |
1092 | } |
1093 | ||
b291f000 NP |
1094 | if (mlocked) |
1095 | goto out; | |
1096 | ||
1da177e4 LT |
1097 | if (list_empty(&mapping->i_mmap_nonlinear)) |
1098 | goto out; | |
1099 | ||
1100 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
1101 | shared.vm_set.list) { | |
b291f000 NP |
1102 | if (MLOCK_PAGES && unlikely(unlock)) { |
1103 | if (!(vma->vm_flags & VM_LOCKED)) | |
1104 | continue; /* must visit all vmas */ | |
1105 | ret = SWAP_MLOCK; /* leave mlocked == 0 */ | |
1106 | goto out; /* no need to look further */ | |
1107 | } | |
1108 | if (!MLOCK_PAGES && !migration && (vma->vm_flags & VM_LOCKED)) | |
1da177e4 LT |
1109 | continue; |
1110 | cursor = (unsigned long) vma->vm_private_data; | |
1111 | if (cursor > max_nl_cursor) | |
1112 | max_nl_cursor = cursor; | |
1113 | cursor = vma->vm_end - vma->vm_start; | |
1114 | if (cursor > max_nl_size) | |
1115 | max_nl_size = cursor; | |
1116 | } | |
1117 | ||
b291f000 | 1118 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1da177e4 LT |
1119 | ret = SWAP_FAIL; |
1120 | goto out; | |
1121 | } | |
1122 | ||
1123 | /* | |
1124 | * We don't try to search for this page in the nonlinear vmas, | |
1125 | * and page_referenced wouldn't have found it anyway. Instead | |
1126 | * just walk the nonlinear vmas trying to age and unmap some. | |
1127 | * The mapcount of the page we came in with is irrelevant, | |
1128 | * but even so use it as a guide to how hard we should try? | |
1129 | */ | |
1130 | mapcount = page_mapcount(page); | |
1131 | if (!mapcount) | |
1132 | goto out; | |
1133 | cond_resched_lock(&mapping->i_mmap_lock); | |
1134 | ||
1135 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
1136 | if (max_nl_cursor == 0) | |
1137 | max_nl_cursor = CLUSTER_SIZE; | |
1138 | ||
1139 | do { | |
1140 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
1141 | shared.vm_set.list) { | |
b291f000 NP |
1142 | if (!MLOCK_PAGES && !migration && |
1143 | (vma->vm_flags & VM_LOCKED)) | |
1da177e4 LT |
1144 | continue; |
1145 | cursor = (unsigned long) vma->vm_private_data; | |
839b9685 | 1146 | while ( cursor < max_nl_cursor && |
1da177e4 | 1147 | cursor < vma->vm_end - vma->vm_start) { |
b291f000 NP |
1148 | ret = try_to_unmap_cluster(cursor, &mapcount, |
1149 | vma, page); | |
1150 | if (ret == SWAP_MLOCK) | |
1151 | mlocked = 2; /* to return below */ | |
1da177e4 LT |
1152 | cursor += CLUSTER_SIZE; |
1153 | vma->vm_private_data = (void *) cursor; | |
1154 | if ((int)mapcount <= 0) | |
1155 | goto out; | |
1156 | } | |
1157 | vma->vm_private_data = (void *) max_nl_cursor; | |
1158 | } | |
1159 | cond_resched_lock(&mapping->i_mmap_lock); | |
1160 | max_nl_cursor += CLUSTER_SIZE; | |
1161 | } while (max_nl_cursor <= max_nl_size); | |
1162 | ||
1163 | /* | |
1164 | * Don't loop forever (perhaps all the remaining pages are | |
1165 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
1166 | * vmas, now forgetting on which ones it had fallen behind. | |
1167 | */ | |
101d2be7 HD |
1168 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
1169 | vma->vm_private_data = NULL; | |
1da177e4 LT |
1170 | out: |
1171 | spin_unlock(&mapping->i_mmap_lock); | |
b291f000 NP |
1172 | if (mlocked) |
1173 | ret = SWAP_MLOCK; /* actually mlocked the page */ | |
1174 | else if (ret == SWAP_MLOCK) | |
1175 | ret = SWAP_AGAIN; /* saw VM_LOCKED vma */ | |
1da177e4 LT |
1176 | return ret; |
1177 | } | |
1178 | ||
1179 | /** | |
1180 | * try_to_unmap - try to remove all page table mappings to a page | |
1181 | * @page: the page to get unmapped | |
43d8eac4 | 1182 | * @migration: migration flag |
1da177e4 LT |
1183 | * |
1184 | * Tries to remove all the page table entries which are mapping this | |
1185 | * page, used in the pageout path. Caller must hold the page lock. | |
1186 | * Return values are: | |
1187 | * | |
1188 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
1189 | * SWAP_AGAIN - we missed a mapping, try again later | |
1190 | * SWAP_FAIL - the page is unswappable | |
b291f000 | 1191 | * SWAP_MLOCK - page is mlocked. |
1da177e4 | 1192 | */ |
7352349a | 1193 | int try_to_unmap(struct page *page, int migration) |
1da177e4 LT |
1194 | { |
1195 | int ret; | |
1196 | ||
1da177e4 LT |
1197 | BUG_ON(!PageLocked(page)); |
1198 | ||
1199 | if (PageAnon(page)) | |
b291f000 | 1200 | ret = try_to_unmap_anon(page, 0, migration); |
1da177e4 | 1201 | else |
b291f000 NP |
1202 | ret = try_to_unmap_file(page, 0, migration); |
1203 | if (ret != SWAP_MLOCK && !page_mapped(page)) | |
1da177e4 LT |
1204 | ret = SWAP_SUCCESS; |
1205 | return ret; | |
1206 | } | |
81b4082d | 1207 | |
b291f000 NP |
1208 | #ifdef CONFIG_UNEVICTABLE_LRU |
1209 | /** | |
1210 | * try_to_munlock - try to munlock a page | |
1211 | * @page: the page to be munlocked | |
1212 | * | |
1213 | * Called from munlock code. Checks all of the VMAs mapping the page | |
1214 | * to make sure nobody else has this page mlocked. The page will be | |
1215 | * returned with PG_mlocked cleared if no other vmas have it mlocked. | |
1216 | * | |
1217 | * Return values are: | |
1218 | * | |
1219 | * SWAP_SUCCESS - no vma's holding page mlocked. | |
1220 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem | |
1221 | * SWAP_MLOCK - page is now mlocked. | |
1222 | */ | |
1223 | int try_to_munlock(struct page *page) | |
1224 | { | |
1225 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); | |
1226 | ||
1227 | if (PageAnon(page)) | |
1228 | return try_to_unmap_anon(page, 1, 0); | |
1229 | else | |
1230 | return try_to_unmap_file(page, 1, 0); | |
1231 | } | |
1232 | #endif |