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 | |
98f32602 | 17 | * Contributions by Hugh Dickins 2003, 2004 |
1da177e4 LT |
18 | */ |
19 | ||
20 | /* | |
21 | * Lock ordering in mm: | |
22 | * | |
1b1dcc1b | 23 | * inode->i_mutex (while writing or truncating, not reading or faulting) |
82591e6e NP |
24 | * inode->i_alloc_sem (vmtruncate_range) |
25 | * mm->mmap_sem | |
26 | * page->flags PG_locked (lock_page) | |
27 | * mapping->i_mmap_lock | |
28 | * anon_vma->lock | |
29 | * mm->page_table_lock or pte_lock | |
30 | * zone->lru_lock (in mark_page_accessed, isolate_lru_page) | |
31 | * swap_lock (in swap_duplicate, swap_info_get) | |
32 | * mmlist_lock (in mmput, drain_mmlist and others) | |
33 | * mapping->private_lock (in __set_page_dirty_buffers) | |
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> |
8a9f3ccd | 50 | #include <linux/memcontrol.h> |
cddb8a5c | 51 | #include <linux/mmu_notifier.h> |
64cdd548 | 52 | #include <linux/migrate.h> |
1da177e4 LT |
53 | |
54 | #include <asm/tlbflush.h> | |
55 | ||
b291f000 NP |
56 | #include "internal.h" |
57 | ||
fdd2e5f8 AB |
58 | static struct kmem_cache *anon_vma_cachep; |
59 | ||
60 | static inline struct anon_vma *anon_vma_alloc(void) | |
61 | { | |
62 | return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); | |
63 | } | |
64 | ||
65 | static inline void anon_vma_free(struct anon_vma *anon_vma) | |
66 | { | |
67 | kmem_cache_free(anon_vma_cachep, anon_vma); | |
68 | } | |
1da177e4 | 69 | |
d9d332e0 LT |
70 | /** |
71 | * anon_vma_prepare - attach an anon_vma to a memory region | |
72 | * @vma: the memory region in question | |
73 | * | |
74 | * This makes sure the memory mapping described by 'vma' has | |
75 | * an 'anon_vma' attached to it, so that we can associate the | |
76 | * anonymous pages mapped into it with that anon_vma. | |
77 | * | |
78 | * The common case will be that we already have one, but if | |
79 | * if not we either need to find an adjacent mapping that we | |
80 | * can re-use the anon_vma from (very common when the only | |
81 | * reason for splitting a vma has been mprotect()), or we | |
82 | * allocate a new one. | |
83 | * | |
84 | * Anon-vma allocations are very subtle, because we may have | |
85 | * optimistically looked up an anon_vma in page_lock_anon_vma() | |
86 | * and that may actually touch the spinlock even in the newly | |
87 | * allocated vma (it depends on RCU to make sure that the | |
88 | * anon_vma isn't actually destroyed). | |
89 | * | |
90 | * As a result, we need to do proper anon_vma locking even | |
91 | * for the new allocation. At the same time, we do not want | |
92 | * to do any locking for the common case of already having | |
93 | * an anon_vma. | |
94 | * | |
95 | * This must be called with the mmap_sem held for reading. | |
96 | */ | |
1da177e4 LT |
97 | int anon_vma_prepare(struct vm_area_struct *vma) |
98 | { | |
99 | struct anon_vma *anon_vma = vma->anon_vma; | |
100 | ||
101 | might_sleep(); | |
102 | if (unlikely(!anon_vma)) { | |
103 | struct mm_struct *mm = vma->vm_mm; | |
d9d332e0 | 104 | struct anon_vma *allocated; |
1da177e4 LT |
105 | |
106 | anon_vma = find_mergeable_anon_vma(vma); | |
d9d332e0 LT |
107 | allocated = NULL; |
108 | if (!anon_vma) { | |
1da177e4 LT |
109 | anon_vma = anon_vma_alloc(); |
110 | if (unlikely(!anon_vma)) | |
111 | return -ENOMEM; | |
112 | allocated = anon_vma; | |
1da177e4 | 113 | } |
d9d332e0 | 114 | spin_lock(&anon_vma->lock); |
1da177e4 LT |
115 | |
116 | /* page_table_lock to protect against threads */ | |
117 | spin_lock(&mm->page_table_lock); | |
118 | if (likely(!vma->anon_vma)) { | |
119 | vma->anon_vma = anon_vma; | |
0697212a | 120 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
121 | allocated = NULL; |
122 | } | |
123 | spin_unlock(&mm->page_table_lock); | |
124 | ||
d9d332e0 | 125 | spin_unlock(&anon_vma->lock); |
1da177e4 LT |
126 | if (unlikely(allocated)) |
127 | anon_vma_free(allocated); | |
128 | } | |
129 | return 0; | |
130 | } | |
131 | ||
132 | void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) | |
133 | { | |
134 | BUG_ON(vma->anon_vma != next->anon_vma); | |
135 | list_del(&next->anon_vma_node); | |
136 | } | |
137 | ||
138 | void __anon_vma_link(struct vm_area_struct *vma) | |
139 | { | |
140 | struct anon_vma *anon_vma = vma->anon_vma; | |
141 | ||
30acbaba | 142 | if (anon_vma) |
0697212a | 143 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
144 | } |
145 | ||
146 | void anon_vma_link(struct vm_area_struct *vma) | |
147 | { | |
148 | struct anon_vma *anon_vma = vma->anon_vma; | |
149 | ||
150 | if (anon_vma) { | |
151 | spin_lock(&anon_vma->lock); | |
0697212a | 152 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
1da177e4 LT |
153 | spin_unlock(&anon_vma->lock); |
154 | } | |
155 | } | |
156 | ||
157 | void anon_vma_unlink(struct vm_area_struct *vma) | |
158 | { | |
159 | struct anon_vma *anon_vma = vma->anon_vma; | |
160 | int empty; | |
161 | ||
162 | if (!anon_vma) | |
163 | return; | |
164 | ||
165 | spin_lock(&anon_vma->lock); | |
1da177e4 LT |
166 | list_del(&vma->anon_vma_node); |
167 | ||
168 | /* We must garbage collect the anon_vma if it's empty */ | |
169 | empty = list_empty(&anon_vma->head); | |
170 | spin_unlock(&anon_vma->lock); | |
171 | ||
172 | if (empty) | |
173 | anon_vma_free(anon_vma); | |
174 | } | |
175 | ||
51cc5068 | 176 | static void anon_vma_ctor(void *data) |
1da177e4 | 177 | { |
a35afb83 | 178 | struct anon_vma *anon_vma = data; |
1da177e4 | 179 | |
a35afb83 CL |
180 | spin_lock_init(&anon_vma->lock); |
181 | INIT_LIST_HEAD(&anon_vma->head); | |
1da177e4 LT |
182 | } |
183 | ||
184 | void __init anon_vma_init(void) | |
185 | { | |
186 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), | |
20c2df83 | 187 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
1da177e4 LT |
188 | } |
189 | ||
190 | /* | |
191 | * Getting a lock on a stable anon_vma from a page off the LRU is | |
192 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. | |
193 | */ | |
2afd1c92 | 194 | static struct anon_vma *page_lock_anon_vma(struct page *page) |
1da177e4 | 195 | { |
34bbd704 | 196 | struct anon_vma *anon_vma; |
1da177e4 LT |
197 | unsigned long anon_mapping; |
198 | ||
199 | rcu_read_lock(); | |
200 | anon_mapping = (unsigned long) page->mapping; | |
201 | if (!(anon_mapping & PAGE_MAPPING_ANON)) | |
202 | goto out; | |
203 | if (!page_mapped(page)) | |
204 | goto out; | |
205 | ||
206 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); | |
207 | spin_lock(&anon_vma->lock); | |
34bbd704 | 208 | return anon_vma; |
1da177e4 LT |
209 | out: |
210 | rcu_read_unlock(); | |
34bbd704 ON |
211 | return NULL; |
212 | } | |
213 | ||
2afd1c92 | 214 | static void page_unlock_anon_vma(struct anon_vma *anon_vma) |
34bbd704 ON |
215 | { |
216 | spin_unlock(&anon_vma->lock); | |
217 | rcu_read_unlock(); | |
1da177e4 LT |
218 | } |
219 | ||
220 | /* | |
3ad33b24 LS |
221 | * At what user virtual address is page expected in @vma? |
222 | * Returns virtual address or -EFAULT if page's index/offset is not | |
223 | * within the range mapped the @vma. | |
1da177e4 LT |
224 | */ |
225 | static inline unsigned long | |
226 | vma_address(struct page *page, struct vm_area_struct *vma) | |
227 | { | |
228 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
229 | unsigned long address; | |
230 | ||
231 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); | |
232 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { | |
3ad33b24 | 233 | /* page should be within @vma mapping range */ |
1da177e4 LT |
234 | return -EFAULT; |
235 | } | |
236 | return address; | |
237 | } | |
238 | ||
239 | /* | |
240 | * At what user virtual address is page expected in vma? checking that the | |
ee498ed7 | 241 | * page matches the vma: currently only used on anon pages, by unuse_vma; |
1da177e4 LT |
242 | */ |
243 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) | |
244 | { | |
245 | if (PageAnon(page)) { | |
246 | if ((void *)vma->anon_vma != | |
247 | (void *)page->mapping - PAGE_MAPPING_ANON) | |
248 | return -EFAULT; | |
249 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { | |
ee498ed7 HD |
250 | if (!vma->vm_file || |
251 | vma->vm_file->f_mapping != page->mapping) | |
1da177e4 LT |
252 | return -EFAULT; |
253 | } else | |
254 | return -EFAULT; | |
255 | return vma_address(page, vma); | |
256 | } | |
257 | ||
81b4082d ND |
258 | /* |
259 | * Check that @page is mapped at @address into @mm. | |
260 | * | |
479db0bf NP |
261 | * If @sync is false, page_check_address may perform a racy check to avoid |
262 | * the page table lock when the pte is not present (helpful when reclaiming | |
263 | * highly shared pages). | |
264 | * | |
b8072f09 | 265 | * On success returns with pte mapped and locked. |
81b4082d | 266 | */ |
ceffc078 | 267 | pte_t *page_check_address(struct page *page, struct mm_struct *mm, |
479db0bf | 268 | unsigned long address, spinlock_t **ptlp, int sync) |
81b4082d ND |
269 | { |
270 | pgd_t *pgd; | |
271 | pud_t *pud; | |
272 | pmd_t *pmd; | |
273 | pte_t *pte; | |
c0718806 | 274 | spinlock_t *ptl; |
81b4082d | 275 | |
81b4082d | 276 | pgd = pgd_offset(mm, address); |
c0718806 HD |
277 | if (!pgd_present(*pgd)) |
278 | return NULL; | |
279 | ||
280 | pud = pud_offset(pgd, address); | |
281 | if (!pud_present(*pud)) | |
282 | return NULL; | |
283 | ||
284 | pmd = pmd_offset(pud, address); | |
285 | if (!pmd_present(*pmd)) | |
286 | return NULL; | |
287 | ||
288 | pte = pte_offset_map(pmd, address); | |
289 | /* Make a quick check before getting the lock */ | |
479db0bf | 290 | if (!sync && !pte_present(*pte)) { |
c0718806 HD |
291 | pte_unmap(pte); |
292 | return NULL; | |
293 | } | |
294 | ||
4c21e2f2 | 295 | ptl = pte_lockptr(mm, pmd); |
c0718806 HD |
296 | spin_lock(ptl); |
297 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { | |
298 | *ptlp = ptl; | |
299 | return pte; | |
81b4082d | 300 | } |
c0718806 HD |
301 | pte_unmap_unlock(pte, ptl); |
302 | return NULL; | |
81b4082d ND |
303 | } |
304 | ||
b291f000 NP |
305 | /** |
306 | * page_mapped_in_vma - check whether a page is really mapped in a VMA | |
307 | * @page: the page to test | |
308 | * @vma: the VMA to test | |
309 | * | |
310 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 | |
311 | * if the page is not mapped into the page tables of this VMA. Only | |
312 | * valid for normal file or anonymous VMAs. | |
313 | */ | |
314 | static int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) | |
315 | { | |
316 | unsigned long address; | |
317 | pte_t *pte; | |
318 | spinlock_t *ptl; | |
319 | ||
320 | address = vma_address(page, vma); | |
321 | if (address == -EFAULT) /* out of vma range */ | |
322 | return 0; | |
323 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); | |
324 | if (!pte) /* the page is not in this mm */ | |
325 | return 0; | |
326 | pte_unmap_unlock(pte, ptl); | |
327 | ||
328 | return 1; | |
329 | } | |
330 | ||
1da177e4 LT |
331 | /* |
332 | * Subfunctions of page_referenced: page_referenced_one called | |
333 | * repeatedly from either page_referenced_anon or page_referenced_file. | |
334 | */ | |
335 | static int page_referenced_one(struct page *page, | |
6fe6b7e3 WF |
336 | struct vm_area_struct *vma, |
337 | unsigned int *mapcount, | |
338 | unsigned long *vm_flags) | |
1da177e4 LT |
339 | { |
340 | struct mm_struct *mm = vma->vm_mm; | |
341 | unsigned long address; | |
1da177e4 | 342 | pte_t *pte; |
c0718806 | 343 | spinlock_t *ptl; |
1da177e4 LT |
344 | int referenced = 0; |
345 | ||
1da177e4 LT |
346 | address = vma_address(page, vma); |
347 | if (address == -EFAULT) | |
348 | goto out; | |
349 | ||
479db0bf | 350 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 HD |
351 | if (!pte) |
352 | goto out; | |
1da177e4 | 353 | |
b291f000 NP |
354 | /* |
355 | * Don't want to elevate referenced for mlocked page that gets this far, | |
356 | * in order that it progresses to try_to_unmap and is moved to the | |
357 | * unevictable list. | |
358 | */ | |
5a9bbdcd | 359 | if (vma->vm_flags & VM_LOCKED) { |
5a9bbdcd | 360 | *mapcount = 1; /* break early from loop */ |
03ef83af | 361 | *vm_flags |= VM_LOCKED; |
b291f000 NP |
362 | goto out_unmap; |
363 | } | |
364 | ||
4917e5d0 JW |
365 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
366 | /* | |
367 | * Don't treat a reference through a sequentially read | |
368 | * mapping as such. If the page has been used in | |
369 | * another mapping, we will catch it; if this other | |
370 | * mapping is already gone, the unmap path will have | |
371 | * set PG_referenced or activated the page. | |
372 | */ | |
373 | if (likely(!VM_SequentialReadHint(vma))) | |
374 | referenced++; | |
375 | } | |
1da177e4 | 376 | |
c0718806 HD |
377 | /* Pretend the page is referenced if the task has the |
378 | swap token and is in the middle of a page fault. */ | |
f7b7fd8f | 379 | if (mm != current->mm && has_swap_token(mm) && |
c0718806 HD |
380 | rwsem_is_locked(&mm->mmap_sem)) |
381 | referenced++; | |
382 | ||
b291f000 | 383 | out_unmap: |
c0718806 HD |
384 | (*mapcount)--; |
385 | pte_unmap_unlock(pte, ptl); | |
1da177e4 | 386 | out: |
6fe6b7e3 WF |
387 | if (referenced) |
388 | *vm_flags |= vma->vm_flags; | |
1da177e4 LT |
389 | return referenced; |
390 | } | |
391 | ||
bed7161a | 392 | static int page_referenced_anon(struct page *page, |
6fe6b7e3 WF |
393 | struct mem_cgroup *mem_cont, |
394 | unsigned long *vm_flags) | |
1da177e4 LT |
395 | { |
396 | unsigned int mapcount; | |
397 | struct anon_vma *anon_vma; | |
398 | struct vm_area_struct *vma; | |
399 | int referenced = 0; | |
400 | ||
401 | anon_vma = page_lock_anon_vma(page); | |
402 | if (!anon_vma) | |
403 | return referenced; | |
404 | ||
405 | mapcount = page_mapcount(page); | |
406 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
bed7161a BS |
407 | /* |
408 | * If we are reclaiming on behalf of a cgroup, skip | |
409 | * counting on behalf of references from different | |
410 | * cgroups | |
411 | */ | |
bd845e38 | 412 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 413 | continue; |
6fe6b7e3 WF |
414 | referenced += page_referenced_one(page, vma, |
415 | &mapcount, vm_flags); | |
1da177e4 LT |
416 | if (!mapcount) |
417 | break; | |
418 | } | |
34bbd704 ON |
419 | |
420 | page_unlock_anon_vma(anon_vma); | |
1da177e4 LT |
421 | return referenced; |
422 | } | |
423 | ||
424 | /** | |
425 | * page_referenced_file - referenced check for object-based rmap | |
426 | * @page: the page we're checking references on. | |
43d8eac4 | 427 | * @mem_cont: target memory controller |
6fe6b7e3 | 428 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
429 | * |
430 | * For an object-based mapped page, find all the places it is mapped and | |
431 | * check/clear the referenced flag. This is done by following the page->mapping | |
432 | * pointer, then walking the chain of vmas it holds. It returns the number | |
433 | * of references it found. | |
434 | * | |
435 | * This function is only called from page_referenced for object-based pages. | |
436 | */ | |
bed7161a | 437 | static int page_referenced_file(struct page *page, |
6fe6b7e3 WF |
438 | struct mem_cgroup *mem_cont, |
439 | unsigned long *vm_flags) | |
1da177e4 LT |
440 | { |
441 | unsigned int mapcount; | |
442 | struct address_space *mapping = page->mapping; | |
443 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
444 | struct vm_area_struct *vma; | |
445 | struct prio_tree_iter iter; | |
446 | int referenced = 0; | |
447 | ||
448 | /* | |
449 | * The caller's checks on page->mapping and !PageAnon have made | |
450 | * sure that this is a file page: the check for page->mapping | |
451 | * excludes the case just before it gets set on an anon page. | |
452 | */ | |
453 | BUG_ON(PageAnon(page)); | |
454 | ||
455 | /* | |
456 | * The page lock not only makes sure that page->mapping cannot | |
457 | * suddenly be NULLified by truncation, it makes sure that the | |
458 | * structure at mapping cannot be freed and reused yet, | |
459 | * so we can safely take mapping->i_mmap_lock. | |
460 | */ | |
461 | BUG_ON(!PageLocked(page)); | |
462 | ||
463 | spin_lock(&mapping->i_mmap_lock); | |
464 | ||
465 | /* | |
466 | * i_mmap_lock does not stabilize mapcount at all, but mapcount | |
467 | * is more likely to be accurate if we note it after spinning. | |
468 | */ | |
469 | mapcount = page_mapcount(page); | |
470 | ||
471 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
bed7161a BS |
472 | /* |
473 | * If we are reclaiming on behalf of a cgroup, skip | |
474 | * counting on behalf of references from different | |
475 | * cgroups | |
476 | */ | |
bd845e38 | 477 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
bed7161a | 478 | continue; |
6fe6b7e3 WF |
479 | referenced += page_referenced_one(page, vma, |
480 | &mapcount, vm_flags); | |
1da177e4 LT |
481 | if (!mapcount) |
482 | break; | |
483 | } | |
484 | ||
485 | spin_unlock(&mapping->i_mmap_lock); | |
486 | return referenced; | |
487 | } | |
488 | ||
489 | /** | |
490 | * page_referenced - test if the page was referenced | |
491 | * @page: the page to test | |
492 | * @is_locked: caller holds lock on the page | |
43d8eac4 | 493 | * @mem_cont: target memory controller |
6fe6b7e3 | 494 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
1da177e4 LT |
495 | * |
496 | * Quick test_and_clear_referenced for all mappings to a page, | |
497 | * returns the number of ptes which referenced the page. | |
498 | */ | |
6fe6b7e3 WF |
499 | int page_referenced(struct page *page, |
500 | int is_locked, | |
501 | struct mem_cgroup *mem_cont, | |
502 | unsigned long *vm_flags) | |
1da177e4 LT |
503 | { |
504 | int referenced = 0; | |
505 | ||
1da177e4 LT |
506 | if (TestClearPageReferenced(page)) |
507 | referenced++; | |
508 | ||
6fe6b7e3 | 509 | *vm_flags = 0; |
1da177e4 LT |
510 | if (page_mapped(page) && page->mapping) { |
511 | if (PageAnon(page)) | |
6fe6b7e3 WF |
512 | referenced += page_referenced_anon(page, mem_cont, |
513 | vm_flags); | |
1da177e4 | 514 | else if (is_locked) |
6fe6b7e3 WF |
515 | referenced += page_referenced_file(page, mem_cont, |
516 | vm_flags); | |
529ae9aa | 517 | else if (!trylock_page(page)) |
1da177e4 LT |
518 | referenced++; |
519 | else { | |
520 | if (page->mapping) | |
6fe6b7e3 WF |
521 | referenced += page_referenced_file(page, |
522 | mem_cont, vm_flags); | |
1da177e4 LT |
523 | unlock_page(page); |
524 | } | |
525 | } | |
5b7baf05 CB |
526 | |
527 | if (page_test_and_clear_young(page)) | |
528 | referenced++; | |
529 | ||
1da177e4 LT |
530 | return referenced; |
531 | } | |
532 | ||
d08b3851 PZ |
533 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) |
534 | { | |
535 | struct mm_struct *mm = vma->vm_mm; | |
536 | unsigned long address; | |
c2fda5fe | 537 | pte_t *pte; |
d08b3851 PZ |
538 | spinlock_t *ptl; |
539 | int ret = 0; | |
540 | ||
541 | address = vma_address(page, vma); | |
542 | if (address == -EFAULT) | |
543 | goto out; | |
544 | ||
479db0bf | 545 | pte = page_check_address(page, mm, address, &ptl, 1); |
d08b3851 PZ |
546 | if (!pte) |
547 | goto out; | |
548 | ||
c2fda5fe PZ |
549 | if (pte_dirty(*pte) || pte_write(*pte)) { |
550 | pte_t entry; | |
d08b3851 | 551 | |
c2fda5fe | 552 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 553 | entry = ptep_clear_flush_notify(vma, address, pte); |
c2fda5fe PZ |
554 | entry = pte_wrprotect(entry); |
555 | entry = pte_mkclean(entry); | |
d6e88e67 | 556 | set_pte_at(mm, address, pte, entry); |
c2fda5fe PZ |
557 | ret = 1; |
558 | } | |
d08b3851 | 559 | |
d08b3851 PZ |
560 | pte_unmap_unlock(pte, ptl); |
561 | out: | |
562 | return ret; | |
563 | } | |
564 | ||
565 | static int page_mkclean_file(struct address_space *mapping, struct page *page) | |
566 | { | |
567 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
568 | struct vm_area_struct *vma; | |
569 | struct prio_tree_iter iter; | |
570 | int ret = 0; | |
571 | ||
572 | BUG_ON(PageAnon(page)); | |
573 | ||
574 | spin_lock(&mapping->i_mmap_lock); | |
575 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
576 | if (vma->vm_flags & VM_SHARED) | |
577 | ret += page_mkclean_one(page, vma); | |
578 | } | |
579 | spin_unlock(&mapping->i_mmap_lock); | |
580 | return ret; | |
581 | } | |
582 | ||
583 | int page_mkclean(struct page *page) | |
584 | { | |
585 | int ret = 0; | |
586 | ||
587 | BUG_ON(!PageLocked(page)); | |
588 | ||
589 | if (page_mapped(page)) { | |
590 | struct address_space *mapping = page_mapping(page); | |
ce7e9fae | 591 | if (mapping) { |
d08b3851 | 592 | ret = page_mkclean_file(mapping, page); |
ce7e9fae CB |
593 | if (page_test_dirty(page)) { |
594 | page_clear_dirty(page); | |
595 | ret = 1; | |
596 | } | |
6c210482 | 597 | } |
d08b3851 PZ |
598 | } |
599 | ||
600 | return ret; | |
601 | } | |
60b59bea | 602 | EXPORT_SYMBOL_GPL(page_mkclean); |
d08b3851 | 603 | |
9617d95e | 604 | /** |
43d8eac4 | 605 | * __page_set_anon_rmap - setup new anonymous rmap |
9617d95e 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_set_anon_rmap(struct page *page, | |
611 | struct vm_area_struct *vma, unsigned long address) | |
612 | { | |
613 | struct anon_vma *anon_vma = vma->anon_vma; | |
614 | ||
615 | BUG_ON(!anon_vma); | |
616 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
617 | page->mapping = (struct address_space *) anon_vma; | |
618 | ||
619 | page->index = linear_page_index(vma, address); | |
620 | ||
a74609fa NP |
621 | /* |
622 | * nr_mapped state can be updated without turning off | |
623 | * interrupts because it is not modified via interrupt. | |
624 | */ | |
f3dbd344 | 625 | __inc_zone_page_state(page, NR_ANON_PAGES); |
9617d95e NP |
626 | } |
627 | ||
c97a9e10 | 628 | /** |
43d8eac4 | 629 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
c97a9e10 NP |
630 | * @page: the page to add the mapping to |
631 | * @vma: the vm area in which the mapping is added | |
632 | * @address: the user virtual address mapped | |
633 | */ | |
634 | static void __page_check_anon_rmap(struct page *page, | |
635 | struct vm_area_struct *vma, unsigned long address) | |
636 | { | |
637 | #ifdef CONFIG_DEBUG_VM | |
638 | /* | |
639 | * The page's anon-rmap details (mapping and index) are guaranteed to | |
640 | * be set up correctly at this point. | |
641 | * | |
642 | * We have exclusion against page_add_anon_rmap because the caller | |
643 | * always holds the page locked, except if called from page_dup_rmap, | |
644 | * in which case the page is already known to be setup. | |
645 | * | |
646 | * We have exclusion against page_add_new_anon_rmap because those pages | |
647 | * are initially only visible via the pagetables, and the pte is locked | |
648 | * over the call to page_add_new_anon_rmap. | |
649 | */ | |
650 | struct anon_vma *anon_vma = vma->anon_vma; | |
651 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; | |
652 | BUG_ON(page->mapping != (struct address_space *)anon_vma); | |
653 | BUG_ON(page->index != linear_page_index(vma, address)); | |
654 | #endif | |
655 | } | |
656 | ||
1da177e4 LT |
657 | /** |
658 | * page_add_anon_rmap - add pte mapping to an anonymous page | |
659 | * @page: the page to add the mapping to | |
660 | * @vma: the vm area in which the mapping is added | |
661 | * @address: the user virtual address mapped | |
662 | * | |
c97a9e10 | 663 | * The caller needs to hold the pte lock and the page must be locked. |
1da177e4 LT |
664 | */ |
665 | void page_add_anon_rmap(struct page *page, | |
666 | struct vm_area_struct *vma, unsigned long address) | |
667 | { | |
c97a9e10 NP |
668 | VM_BUG_ON(!PageLocked(page)); |
669 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); | |
9617d95e NP |
670 | if (atomic_inc_and_test(&page->_mapcount)) |
671 | __page_set_anon_rmap(page, vma, address); | |
69029cd5 | 672 | else |
c97a9e10 | 673 | __page_check_anon_rmap(page, vma, address); |
1da177e4 LT |
674 | } |
675 | ||
43d8eac4 | 676 | /** |
9617d95e NP |
677 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
678 | * @page: the page to add the mapping to | |
679 | * @vma: the vm area in which the mapping is added | |
680 | * @address: the user virtual address mapped | |
681 | * | |
682 | * Same as page_add_anon_rmap but must only be called on *new* pages. | |
683 | * This means the inc-and-test can be bypassed. | |
c97a9e10 | 684 | * Page does not have to be locked. |
9617d95e NP |
685 | */ |
686 | void page_add_new_anon_rmap(struct page *page, | |
687 | struct vm_area_struct *vma, unsigned long address) | |
688 | { | |
b5934c53 | 689 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
cbf84b7a HD |
690 | SetPageSwapBacked(page); |
691 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ | |
9617d95e | 692 | __page_set_anon_rmap(page, vma, address); |
b5934c53 | 693 | if (page_evictable(page, vma)) |
cbf84b7a | 694 | lru_cache_add_lru(page, LRU_ACTIVE_ANON); |
b5934c53 HD |
695 | else |
696 | add_page_to_unevictable_list(page); | |
9617d95e NP |
697 | } |
698 | ||
1da177e4 LT |
699 | /** |
700 | * page_add_file_rmap - add pte mapping to a file page | |
701 | * @page: the page to add the mapping to | |
702 | * | |
b8072f09 | 703 | * The caller needs to hold the pte lock. |
1da177e4 LT |
704 | */ |
705 | void page_add_file_rmap(struct page *page) | |
706 | { | |
d69b042f | 707 | if (atomic_inc_and_test(&page->_mapcount)) { |
65ba55f5 | 708 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
d69b042f BS |
709 | mem_cgroup_update_mapped_file_stat(page, 1); |
710 | } | |
1da177e4 LT |
711 | } |
712 | ||
c97a9e10 NP |
713 | #ifdef CONFIG_DEBUG_VM |
714 | /** | |
715 | * page_dup_rmap - duplicate pte mapping to a page | |
716 | * @page: the page to add the mapping to | |
43d8eac4 RD |
717 | * @vma: the vm area being duplicated |
718 | * @address: the user virtual address mapped | |
c97a9e10 NP |
719 | * |
720 | * For copy_page_range only: minimal extract from page_add_file_rmap / | |
721 | * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's | |
722 | * quicker. | |
723 | * | |
724 | * The caller needs to hold the pte lock. | |
725 | */ | |
726 | void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) | |
727 | { | |
c97a9e10 NP |
728 | if (PageAnon(page)) |
729 | __page_check_anon_rmap(page, vma, address); | |
730 | atomic_inc(&page->_mapcount); | |
731 | } | |
732 | #endif | |
733 | ||
1da177e4 LT |
734 | /** |
735 | * page_remove_rmap - take down pte mapping from a page | |
736 | * @page: page to remove mapping from | |
737 | * | |
b8072f09 | 738 | * The caller needs to hold the pte lock. |
1da177e4 | 739 | */ |
edc315fd | 740 | void page_remove_rmap(struct page *page) |
1da177e4 | 741 | { |
1da177e4 | 742 | if (atomic_add_negative(-1, &page->_mapcount)) { |
1da177e4 | 743 | /* |
16f8c5b2 HD |
744 | * Now that the last pte has gone, s390 must transfer dirty |
745 | * flag from storage key to struct page. We can usually skip | |
746 | * this if the page is anon, so about to be freed; but perhaps | |
747 | * not if it's in swapcache - there might be another pte slot | |
748 | * containing the swap entry, but page not yet written to swap. | |
1da177e4 | 749 | */ |
a4b526b3 MS |
750 | if ((!PageAnon(page) || PageSwapCache(page)) && |
751 | page_test_dirty(page)) { | |
6c210482 | 752 | page_clear_dirty(page); |
1da177e4 | 753 | set_page_dirty(page); |
6c210482 | 754 | } |
5b4e655e KH |
755 | if (PageAnon(page)) |
756 | mem_cgroup_uncharge_page(page); | |
f3dbd344 | 757 | __dec_zone_page_state(page, |
16f8c5b2 | 758 | PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); |
d69b042f | 759 | mem_cgroup_update_mapped_file_stat(page, -1); |
16f8c5b2 HD |
760 | /* |
761 | * It would be tidy to reset the PageAnon mapping here, | |
762 | * but that might overwrite a racing page_add_anon_rmap | |
763 | * which increments mapcount after us but sets mapping | |
764 | * before us: so leave the reset to free_hot_cold_page, | |
765 | * and remember that it's only reliable while mapped. | |
766 | * Leaving it set also helps swapoff to reinstate ptes | |
767 | * faster for those pages still in swapcache. | |
768 | */ | |
1da177e4 LT |
769 | } |
770 | } | |
771 | ||
772 | /* | |
773 | * Subfunctions of try_to_unmap: try_to_unmap_one called | |
774 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. | |
775 | */ | |
a48d07af | 776 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
7352349a | 777 | int migration) |
1da177e4 LT |
778 | { |
779 | struct mm_struct *mm = vma->vm_mm; | |
780 | unsigned long address; | |
1da177e4 LT |
781 | pte_t *pte; |
782 | pte_t pteval; | |
c0718806 | 783 | spinlock_t *ptl; |
1da177e4 LT |
784 | int ret = SWAP_AGAIN; |
785 | ||
1da177e4 LT |
786 | address = vma_address(page, vma); |
787 | if (address == -EFAULT) | |
788 | goto out; | |
789 | ||
479db0bf | 790 | pte = page_check_address(page, mm, address, &ptl, 0); |
c0718806 | 791 | if (!pte) |
81b4082d | 792 | goto out; |
1da177e4 LT |
793 | |
794 | /* | |
795 | * If the page is mlock()d, we cannot swap it out. | |
796 | * If it's recently referenced (perhaps page_referenced | |
797 | * skipped over this mm) then we should reactivate it. | |
798 | */ | |
b291f000 NP |
799 | if (!migration) { |
800 | if (vma->vm_flags & VM_LOCKED) { | |
801 | ret = SWAP_MLOCK; | |
802 | goto out_unmap; | |
803 | } | |
804 | if (ptep_clear_flush_young_notify(vma, address, pte)) { | |
805 | ret = SWAP_FAIL; | |
806 | goto out_unmap; | |
807 | } | |
808 | } | |
1da177e4 | 809 | |
1da177e4 LT |
810 | /* Nuke the page table entry. */ |
811 | flush_cache_page(vma, address, page_to_pfn(page)); | |
cddb8a5c | 812 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
813 | |
814 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
815 | if (pte_dirty(pteval)) | |
816 | set_page_dirty(page); | |
817 | ||
365e9c87 HD |
818 | /* Update high watermark before we lower rss */ |
819 | update_hiwater_rss(mm); | |
820 | ||
1da177e4 | 821 | if (PageAnon(page)) { |
4c21e2f2 | 822 | swp_entry_t entry = { .val = page_private(page) }; |
0697212a CL |
823 | |
824 | if (PageSwapCache(page)) { | |
825 | /* | |
826 | * Store the swap location in the pte. | |
827 | * See handle_pte_fault() ... | |
828 | */ | |
829 | swap_duplicate(entry); | |
830 | if (list_empty(&mm->mmlist)) { | |
831 | spin_lock(&mmlist_lock); | |
832 | if (list_empty(&mm->mmlist)) | |
833 | list_add(&mm->mmlist, &init_mm.mmlist); | |
834 | spin_unlock(&mmlist_lock); | |
835 | } | |
442c9137 | 836 | dec_mm_counter(mm, anon_rss); |
64cdd548 | 837 | } else if (PAGE_MIGRATION) { |
0697212a CL |
838 | /* |
839 | * Store the pfn of the page in a special migration | |
840 | * pte. do_swap_page() will wait until the migration | |
841 | * pte is removed and then restart fault handling. | |
842 | */ | |
843 | BUG_ON(!migration); | |
844 | entry = make_migration_entry(page, pte_write(pteval)); | |
1da177e4 LT |
845 | } |
846 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
847 | BUG_ON(pte_file(*pte)); | |
64cdd548 | 848 | } else if (PAGE_MIGRATION && migration) { |
04e62a29 CL |
849 | /* Establish migration entry for a file page */ |
850 | swp_entry_t entry; | |
851 | entry = make_migration_entry(page, pte_write(pteval)); | |
852 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); | |
853 | } else | |
4294621f | 854 | dec_mm_counter(mm, file_rss); |
1da177e4 | 855 | |
04e62a29 | 856 | |
edc315fd | 857 | page_remove_rmap(page); |
1da177e4 LT |
858 | page_cache_release(page); |
859 | ||
860 | out_unmap: | |
c0718806 | 861 | pte_unmap_unlock(pte, ptl); |
1da177e4 LT |
862 | out: |
863 | return ret; | |
864 | } | |
865 | ||
866 | /* | |
867 | * objrmap doesn't work for nonlinear VMAs because the assumption that | |
868 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. | |
869 | * Consequently, given a particular page and its ->index, we cannot locate the | |
870 | * ptes which are mapping that page without an exhaustive linear search. | |
871 | * | |
872 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which | |
873 | * maps the file to which the target page belongs. The ->vm_private_data field | |
874 | * holds the current cursor into that scan. Successive searches will circulate | |
875 | * around the vma's virtual address space. | |
876 | * | |
877 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, | |
878 | * more scanning pressure is placed against them as well. Eventually pages | |
879 | * will become fully unmapped and are eligible for eviction. | |
880 | * | |
881 | * For very sparsely populated VMAs this is a little inefficient - chances are | |
882 | * there there won't be many ptes located within the scan cluster. In this case | |
883 | * maybe we could scan further - to the end of the pte page, perhaps. | |
b291f000 NP |
884 | * |
885 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can | |
886 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, | |
887 | * rather than unmapping them. If we encounter the "check_page" that vmscan is | |
888 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. | |
1da177e4 LT |
889 | */ |
890 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) | |
891 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) | |
892 | ||
b291f000 NP |
893 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
894 | struct vm_area_struct *vma, struct page *check_page) | |
1da177e4 LT |
895 | { |
896 | struct mm_struct *mm = vma->vm_mm; | |
897 | pgd_t *pgd; | |
898 | pud_t *pud; | |
899 | pmd_t *pmd; | |
c0718806 | 900 | pte_t *pte; |
1da177e4 | 901 | pte_t pteval; |
c0718806 | 902 | spinlock_t *ptl; |
1da177e4 LT |
903 | struct page *page; |
904 | unsigned long address; | |
905 | unsigned long end; | |
b291f000 NP |
906 | int ret = SWAP_AGAIN; |
907 | int locked_vma = 0; | |
1da177e4 | 908 | |
1da177e4 LT |
909 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
910 | end = address + CLUSTER_SIZE; | |
911 | if (address < vma->vm_start) | |
912 | address = vma->vm_start; | |
913 | if (end > vma->vm_end) | |
914 | end = vma->vm_end; | |
915 | ||
916 | pgd = pgd_offset(mm, address); | |
917 | if (!pgd_present(*pgd)) | |
b291f000 | 918 | return ret; |
1da177e4 LT |
919 | |
920 | pud = pud_offset(pgd, address); | |
921 | if (!pud_present(*pud)) | |
b291f000 | 922 | return ret; |
1da177e4 LT |
923 | |
924 | pmd = pmd_offset(pud, address); | |
925 | if (!pmd_present(*pmd)) | |
b291f000 NP |
926 | return ret; |
927 | ||
928 | /* | |
929 | * MLOCK_PAGES => feature is configured. | |
930 | * if we can acquire the mmap_sem for read, and vma is VM_LOCKED, | |
931 | * keep the sem while scanning the cluster for mlocking pages. | |
932 | */ | |
933 | if (MLOCK_PAGES && down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
934 | locked_vma = (vma->vm_flags & VM_LOCKED); | |
935 | if (!locked_vma) | |
936 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ | |
937 | } | |
c0718806 HD |
938 | |
939 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); | |
1da177e4 | 940 | |
365e9c87 HD |
941 | /* Update high watermark before we lower rss */ |
942 | update_hiwater_rss(mm); | |
943 | ||
c0718806 | 944 | for (; address < end; pte++, address += PAGE_SIZE) { |
1da177e4 LT |
945 | if (!pte_present(*pte)) |
946 | continue; | |
6aab341e LT |
947 | page = vm_normal_page(vma, address, *pte); |
948 | BUG_ON(!page || PageAnon(page)); | |
1da177e4 | 949 | |
b291f000 NP |
950 | if (locked_vma) { |
951 | mlock_vma_page(page); /* no-op if already mlocked */ | |
952 | if (page == check_page) | |
953 | ret = SWAP_MLOCK; | |
954 | continue; /* don't unmap */ | |
955 | } | |
956 | ||
cddb8a5c | 957 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
1da177e4 LT |
958 | continue; |
959 | ||
960 | /* Nuke the page table entry. */ | |
eca35133 | 961 | flush_cache_page(vma, address, pte_pfn(*pte)); |
cddb8a5c | 962 | pteval = ptep_clear_flush_notify(vma, address, pte); |
1da177e4 LT |
963 | |
964 | /* If nonlinear, store the file page offset in the pte. */ | |
965 | if (page->index != linear_page_index(vma, address)) | |
966 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); | |
967 | ||
968 | /* Move the dirty bit to the physical page now the pte is gone. */ | |
969 | if (pte_dirty(pteval)) | |
970 | set_page_dirty(page); | |
971 | ||
edc315fd | 972 | page_remove_rmap(page); |
1da177e4 | 973 | page_cache_release(page); |
4294621f | 974 | dec_mm_counter(mm, file_rss); |
1da177e4 LT |
975 | (*mapcount)--; |
976 | } | |
c0718806 | 977 | pte_unmap_unlock(pte - 1, ptl); |
b291f000 NP |
978 | if (locked_vma) |
979 | up_read(&vma->vm_mm->mmap_sem); | |
980 | return ret; | |
1da177e4 LT |
981 | } |
982 | ||
b291f000 NP |
983 | /* |
984 | * common handling for pages mapped in VM_LOCKED vmas | |
985 | */ | |
986 | static int try_to_mlock_page(struct page *page, struct vm_area_struct *vma) | |
987 | { | |
988 | int mlocked = 0; | |
989 | ||
990 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { | |
991 | if (vma->vm_flags & VM_LOCKED) { | |
992 | mlock_vma_page(page); | |
993 | mlocked++; /* really mlocked the page */ | |
994 | } | |
995 | up_read(&vma->vm_mm->mmap_sem); | |
996 | } | |
997 | return mlocked; | |
998 | } | |
999 | ||
1000 | /** | |
1001 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based | |
1002 | * rmap method | |
1003 | * @page: the page to unmap/unlock | |
1004 | * @unlock: request for unlock rather than unmap [unlikely] | |
1005 | * @migration: unmapping for migration - ignored if @unlock | |
1006 | * | |
1007 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1008 | * contained in the anon_vma struct it points to. | |
1009 | * | |
1010 | * This function is only called from try_to_unmap/try_to_munlock for | |
1011 | * anonymous pages. | |
1012 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1013 | * where the page was found will be held for write. So, we won't recheck | |
1014 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1015 | * 'LOCKED. | |
1016 | */ | |
1017 | static int try_to_unmap_anon(struct page *page, int unlock, int migration) | |
1da177e4 LT |
1018 | { |
1019 | struct anon_vma *anon_vma; | |
1020 | struct vm_area_struct *vma; | |
b291f000 | 1021 | unsigned int mlocked = 0; |
1da177e4 LT |
1022 | int ret = SWAP_AGAIN; |
1023 | ||
b291f000 NP |
1024 | if (MLOCK_PAGES && unlikely(unlock)) |
1025 | ret = SWAP_SUCCESS; /* default for try_to_munlock() */ | |
1026 | ||
1da177e4 LT |
1027 | anon_vma = page_lock_anon_vma(page); |
1028 | if (!anon_vma) | |
1029 | return ret; | |
1030 | ||
1031 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { | |
b291f000 NP |
1032 | if (MLOCK_PAGES && unlikely(unlock)) { |
1033 | if (!((vma->vm_flags & VM_LOCKED) && | |
1034 | page_mapped_in_vma(page, vma))) | |
1035 | continue; /* must visit all unlocked vmas */ | |
1036 | ret = SWAP_MLOCK; /* saw at least one mlocked vma */ | |
1037 | } else { | |
1038 | ret = try_to_unmap_one(page, vma, migration); | |
1039 | if (ret == SWAP_FAIL || !page_mapped(page)) | |
1040 | break; | |
1041 | } | |
1042 | if (ret == SWAP_MLOCK) { | |
1043 | mlocked = try_to_mlock_page(page, vma); | |
1044 | if (mlocked) | |
1045 | break; /* stop if actually mlocked page */ | |
1046 | } | |
1da177e4 | 1047 | } |
34bbd704 ON |
1048 | |
1049 | page_unlock_anon_vma(anon_vma); | |
b291f000 NP |
1050 | |
1051 | if (mlocked) | |
1052 | ret = SWAP_MLOCK; /* actually mlocked the page */ | |
1053 | else if (ret == SWAP_MLOCK) | |
1054 | ret = SWAP_AGAIN; /* saw VM_LOCKED vma */ | |
1055 | ||
1da177e4 LT |
1056 | return ret; |
1057 | } | |
1058 | ||
1059 | /** | |
b291f000 NP |
1060 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
1061 | * @page: the page to unmap/unlock | |
1062 | * @unlock: request for unlock rather than unmap [unlikely] | |
1063 | * @migration: unmapping for migration - ignored if @unlock | |
1da177e4 LT |
1064 | * |
1065 | * Find all the mappings of a page using the mapping pointer and the vma chains | |
1066 | * contained in the address_space struct it points to. | |
1067 | * | |
b291f000 NP |
1068 | * This function is only called from try_to_unmap/try_to_munlock for |
1069 | * object-based pages. | |
1070 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma | |
1071 | * where the page was found will be held for write. So, we won't recheck | |
1072 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be | |
1073 | * 'LOCKED. | |
1da177e4 | 1074 | */ |
b291f000 | 1075 | static int try_to_unmap_file(struct page *page, int unlock, int migration) |
1da177e4 LT |
1076 | { |
1077 | struct address_space *mapping = page->mapping; | |
1078 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); | |
1079 | struct vm_area_struct *vma; | |
1080 | struct prio_tree_iter iter; | |
1081 | int ret = SWAP_AGAIN; | |
1082 | unsigned long cursor; | |
1083 | unsigned long max_nl_cursor = 0; | |
1084 | unsigned long max_nl_size = 0; | |
1085 | unsigned int mapcount; | |
b291f000 NP |
1086 | unsigned int mlocked = 0; |
1087 | ||
1088 | if (MLOCK_PAGES && unlikely(unlock)) | |
1089 | ret = SWAP_SUCCESS; /* default for try_to_munlock() */ | |
1da177e4 LT |
1090 | |
1091 | spin_lock(&mapping->i_mmap_lock); | |
1092 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { | |
b291f000 | 1093 | if (MLOCK_PAGES && unlikely(unlock)) { |
508b9f8e MK |
1094 | if (!((vma->vm_flags & VM_LOCKED) && |
1095 | page_mapped_in_vma(page, vma))) | |
b291f000 NP |
1096 | continue; /* must visit all vmas */ |
1097 | ret = SWAP_MLOCK; | |
1098 | } else { | |
1099 | ret = try_to_unmap_one(page, vma, migration); | |
1100 | if (ret == SWAP_FAIL || !page_mapped(page)) | |
1101 | goto out; | |
1102 | } | |
1103 | if (ret == SWAP_MLOCK) { | |
1104 | mlocked = try_to_mlock_page(page, vma); | |
1105 | if (mlocked) | |
1106 | break; /* stop if actually mlocked page */ | |
1107 | } | |
1da177e4 LT |
1108 | } |
1109 | ||
b291f000 NP |
1110 | if (mlocked) |
1111 | goto out; | |
1112 | ||
1da177e4 LT |
1113 | if (list_empty(&mapping->i_mmap_nonlinear)) |
1114 | goto out; | |
1115 | ||
1116 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
1117 | shared.vm_set.list) { | |
b291f000 NP |
1118 | if (MLOCK_PAGES && unlikely(unlock)) { |
1119 | if (!(vma->vm_flags & VM_LOCKED)) | |
1120 | continue; /* must visit all vmas */ | |
1121 | ret = SWAP_MLOCK; /* leave mlocked == 0 */ | |
1122 | goto out; /* no need to look further */ | |
1123 | } | |
1124 | if (!MLOCK_PAGES && !migration && (vma->vm_flags & VM_LOCKED)) | |
1da177e4 LT |
1125 | continue; |
1126 | cursor = (unsigned long) vma->vm_private_data; | |
1127 | if (cursor > max_nl_cursor) | |
1128 | max_nl_cursor = cursor; | |
1129 | cursor = vma->vm_end - vma->vm_start; | |
1130 | if (cursor > max_nl_size) | |
1131 | max_nl_size = cursor; | |
1132 | } | |
1133 | ||
b291f000 | 1134 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
1da177e4 LT |
1135 | ret = SWAP_FAIL; |
1136 | goto out; | |
1137 | } | |
1138 | ||
1139 | /* | |
1140 | * We don't try to search for this page in the nonlinear vmas, | |
1141 | * and page_referenced wouldn't have found it anyway. Instead | |
1142 | * just walk the nonlinear vmas trying to age and unmap some. | |
1143 | * The mapcount of the page we came in with is irrelevant, | |
1144 | * but even so use it as a guide to how hard we should try? | |
1145 | */ | |
1146 | mapcount = page_mapcount(page); | |
1147 | if (!mapcount) | |
1148 | goto out; | |
1149 | cond_resched_lock(&mapping->i_mmap_lock); | |
1150 | ||
1151 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; | |
1152 | if (max_nl_cursor == 0) | |
1153 | max_nl_cursor = CLUSTER_SIZE; | |
1154 | ||
1155 | do { | |
1156 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, | |
1157 | shared.vm_set.list) { | |
b291f000 NP |
1158 | if (!MLOCK_PAGES && !migration && |
1159 | (vma->vm_flags & VM_LOCKED)) | |
1da177e4 LT |
1160 | continue; |
1161 | cursor = (unsigned long) vma->vm_private_data; | |
839b9685 | 1162 | while ( cursor < max_nl_cursor && |
1da177e4 | 1163 | cursor < vma->vm_end - vma->vm_start) { |
b291f000 NP |
1164 | ret = try_to_unmap_cluster(cursor, &mapcount, |
1165 | vma, page); | |
1166 | if (ret == SWAP_MLOCK) | |
1167 | mlocked = 2; /* to return below */ | |
1da177e4 LT |
1168 | cursor += CLUSTER_SIZE; |
1169 | vma->vm_private_data = (void *) cursor; | |
1170 | if ((int)mapcount <= 0) | |
1171 | goto out; | |
1172 | } | |
1173 | vma->vm_private_data = (void *) max_nl_cursor; | |
1174 | } | |
1175 | cond_resched_lock(&mapping->i_mmap_lock); | |
1176 | max_nl_cursor += CLUSTER_SIZE; | |
1177 | } while (max_nl_cursor <= max_nl_size); | |
1178 | ||
1179 | /* | |
1180 | * Don't loop forever (perhaps all the remaining pages are | |
1181 | * in locked vmas). Reset cursor on all unreserved nonlinear | |
1182 | * vmas, now forgetting on which ones it had fallen behind. | |
1183 | */ | |
101d2be7 HD |
1184 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
1185 | vma->vm_private_data = NULL; | |
1da177e4 LT |
1186 | out: |
1187 | spin_unlock(&mapping->i_mmap_lock); | |
b291f000 NP |
1188 | if (mlocked) |
1189 | ret = SWAP_MLOCK; /* actually mlocked the page */ | |
1190 | else if (ret == SWAP_MLOCK) | |
1191 | ret = SWAP_AGAIN; /* saw VM_LOCKED vma */ | |
1da177e4 LT |
1192 | return ret; |
1193 | } | |
1194 | ||
1195 | /** | |
1196 | * try_to_unmap - try to remove all page table mappings to a page | |
1197 | * @page: the page to get unmapped | |
43d8eac4 | 1198 | * @migration: migration flag |
1da177e4 LT |
1199 | * |
1200 | * Tries to remove all the page table entries which are mapping this | |
1201 | * page, used in the pageout path. Caller must hold the page lock. | |
1202 | * Return values are: | |
1203 | * | |
1204 | * SWAP_SUCCESS - we succeeded in removing all mappings | |
1205 | * SWAP_AGAIN - we missed a mapping, try again later | |
1206 | * SWAP_FAIL - the page is unswappable | |
b291f000 | 1207 | * SWAP_MLOCK - page is mlocked. |
1da177e4 | 1208 | */ |
7352349a | 1209 | int try_to_unmap(struct page *page, int migration) |
1da177e4 LT |
1210 | { |
1211 | int ret; | |
1212 | ||
1da177e4 LT |
1213 | BUG_ON(!PageLocked(page)); |
1214 | ||
1215 | if (PageAnon(page)) | |
b291f000 | 1216 | ret = try_to_unmap_anon(page, 0, migration); |
1da177e4 | 1217 | else |
b291f000 NP |
1218 | ret = try_to_unmap_file(page, 0, migration); |
1219 | if (ret != SWAP_MLOCK && !page_mapped(page)) | |
1da177e4 LT |
1220 | ret = SWAP_SUCCESS; |
1221 | return ret; | |
1222 | } | |
81b4082d | 1223 | |
b291f000 NP |
1224 | /** |
1225 | * try_to_munlock - try to munlock a page | |
1226 | * @page: the page to be munlocked | |
1227 | * | |
1228 | * Called from munlock code. Checks all of the VMAs mapping the page | |
1229 | * to make sure nobody else has this page mlocked. The page will be | |
1230 | * returned with PG_mlocked cleared if no other vmas have it mlocked. | |
1231 | * | |
1232 | * Return values are: | |
1233 | * | |
1234 | * SWAP_SUCCESS - no vma's holding page mlocked. | |
1235 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem | |
1236 | * SWAP_MLOCK - page is now mlocked. | |
1237 | */ | |
1238 | int try_to_munlock(struct page *page) | |
1239 | { | |
1240 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); | |
1241 | ||
1242 | if (PageAnon(page)) | |
1243 | return try_to_unmap_anon(page, 1, 0); | |
1244 | else | |
1245 | return try_to_unmap_file(page, 1, 0); | |
1246 | } | |
68377659 | 1247 |