Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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 | * |
Jes Sorensen | 1b1dcc1 | 2006-01-09 15:59:24 -0800 | [diff] [blame] | 23 | * inode->i_mutex (while writing or truncating, not reading or faulting) |
Nick Piggin | 82591e6 | 2006-10-19 23:29:10 -0700 | [diff] [blame^] | 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) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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> |
Christoph Lameter | a48d07a | 2006-02-01 03:05:38 -0800 | [diff] [blame] | 49 | #include <linux/module.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 50 | |
| 51 | #include <asm/tlbflush.h> |
| 52 | |
Pekka Enberg | fcc234f | 2006-03-22 00:08:13 -0800 | [diff] [blame] | 53 | struct kmem_cache *anon_vma_cachep; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 54 | |
| 55 | static inline void validate_anon_vma(struct vm_area_struct *find_vma) |
| 56 | { |
Nick Piggin | b7ab795 | 2006-03-22 00:08:42 -0800 | [diff] [blame] | 57 | #ifdef CONFIG_DEBUG_VM |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | struct anon_vma *anon_vma = find_vma->anon_vma; |
| 59 | struct vm_area_struct *vma; |
| 60 | unsigned int mapcount = 0; |
| 61 | int found = 0; |
| 62 | |
| 63 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { |
| 64 | mapcount++; |
| 65 | BUG_ON(mapcount > 100000); |
| 66 | if (vma == find_vma) |
| 67 | found = 1; |
| 68 | } |
| 69 | BUG_ON(!found); |
| 70 | #endif |
| 71 | } |
| 72 | |
| 73 | /* This must be called under the mmap_sem. */ |
| 74 | int anon_vma_prepare(struct vm_area_struct *vma) |
| 75 | { |
| 76 | struct anon_vma *anon_vma = vma->anon_vma; |
| 77 | |
| 78 | might_sleep(); |
| 79 | if (unlikely(!anon_vma)) { |
| 80 | struct mm_struct *mm = vma->vm_mm; |
| 81 | struct anon_vma *allocated, *locked; |
| 82 | |
| 83 | anon_vma = find_mergeable_anon_vma(vma); |
| 84 | if (anon_vma) { |
| 85 | allocated = NULL; |
| 86 | locked = anon_vma; |
| 87 | spin_lock(&locked->lock); |
| 88 | } else { |
| 89 | anon_vma = anon_vma_alloc(); |
| 90 | if (unlikely(!anon_vma)) |
| 91 | return -ENOMEM; |
| 92 | allocated = anon_vma; |
| 93 | locked = NULL; |
| 94 | } |
| 95 | |
| 96 | /* page_table_lock to protect against threads */ |
| 97 | spin_lock(&mm->page_table_lock); |
| 98 | if (likely(!vma->anon_vma)) { |
| 99 | vma->anon_vma = anon_vma; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 100 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | allocated = NULL; |
| 102 | } |
| 103 | spin_unlock(&mm->page_table_lock); |
| 104 | |
| 105 | if (locked) |
| 106 | spin_unlock(&locked->lock); |
| 107 | if (unlikely(allocated)) |
| 108 | anon_vma_free(allocated); |
| 109 | } |
| 110 | return 0; |
| 111 | } |
| 112 | |
| 113 | void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) |
| 114 | { |
| 115 | BUG_ON(vma->anon_vma != next->anon_vma); |
| 116 | list_del(&next->anon_vma_node); |
| 117 | } |
| 118 | |
| 119 | void __anon_vma_link(struct vm_area_struct *vma) |
| 120 | { |
| 121 | struct anon_vma *anon_vma = vma->anon_vma; |
| 122 | |
| 123 | if (anon_vma) { |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 124 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 125 | validate_anon_vma(vma); |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | void anon_vma_link(struct vm_area_struct *vma) |
| 130 | { |
| 131 | struct anon_vma *anon_vma = vma->anon_vma; |
| 132 | |
| 133 | if (anon_vma) { |
| 134 | spin_lock(&anon_vma->lock); |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 135 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 136 | validate_anon_vma(vma); |
| 137 | spin_unlock(&anon_vma->lock); |
| 138 | } |
| 139 | } |
| 140 | |
| 141 | void anon_vma_unlink(struct vm_area_struct *vma) |
| 142 | { |
| 143 | struct anon_vma *anon_vma = vma->anon_vma; |
| 144 | int empty; |
| 145 | |
| 146 | if (!anon_vma) |
| 147 | return; |
| 148 | |
| 149 | spin_lock(&anon_vma->lock); |
| 150 | validate_anon_vma(vma); |
| 151 | list_del(&vma->anon_vma_node); |
| 152 | |
| 153 | /* We must garbage collect the anon_vma if it's empty */ |
| 154 | empty = list_empty(&anon_vma->head); |
| 155 | spin_unlock(&anon_vma->lock); |
| 156 | |
| 157 | if (empty) |
| 158 | anon_vma_free(anon_vma); |
| 159 | } |
| 160 | |
Pekka Enberg | fcc234f | 2006-03-22 00:08:13 -0800 | [diff] [blame] | 161 | static void anon_vma_ctor(void *data, struct kmem_cache *cachep, |
| 162 | unsigned long flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 163 | { |
| 164 | if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == |
| 165 | SLAB_CTOR_CONSTRUCTOR) { |
| 166 | struct anon_vma *anon_vma = data; |
| 167 | |
| 168 | spin_lock_init(&anon_vma->lock); |
| 169 | INIT_LIST_HEAD(&anon_vma->head); |
| 170 | } |
| 171 | } |
| 172 | |
| 173 | void __init anon_vma_init(void) |
| 174 | { |
| 175 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), |
| 176 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL); |
| 177 | } |
| 178 | |
| 179 | /* |
| 180 | * Getting a lock on a stable anon_vma from a page off the LRU is |
| 181 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. |
| 182 | */ |
| 183 | static struct anon_vma *page_lock_anon_vma(struct page *page) |
| 184 | { |
| 185 | struct anon_vma *anon_vma = NULL; |
| 186 | unsigned long anon_mapping; |
| 187 | |
| 188 | rcu_read_lock(); |
| 189 | anon_mapping = (unsigned long) page->mapping; |
| 190 | if (!(anon_mapping & PAGE_MAPPING_ANON)) |
| 191 | goto out; |
| 192 | if (!page_mapped(page)) |
| 193 | goto out; |
| 194 | |
| 195 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
| 196 | spin_lock(&anon_vma->lock); |
| 197 | out: |
| 198 | rcu_read_unlock(); |
| 199 | return anon_vma; |
| 200 | } |
| 201 | |
| 202 | /* |
| 203 | * At what user virtual address is page expected in vma? |
| 204 | */ |
| 205 | static inline unsigned long |
| 206 | vma_address(struct page *page, struct vm_area_struct *vma) |
| 207 | { |
| 208 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 209 | unsigned long address; |
| 210 | |
| 211 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
| 212 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { |
| 213 | /* page should be within any vma from prio_tree_next */ |
| 214 | BUG_ON(!PageAnon(page)); |
| 215 | return -EFAULT; |
| 216 | } |
| 217 | return address; |
| 218 | } |
| 219 | |
| 220 | /* |
| 221 | * At what user virtual address is page expected in vma? checking that the |
Hugh Dickins | ee498ed | 2005-11-21 21:32:18 -0800 | [diff] [blame] | 222 | * page matches the vma: currently only used on anon pages, by unuse_vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 223 | */ |
| 224 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) |
| 225 | { |
| 226 | if (PageAnon(page)) { |
| 227 | if ((void *)vma->anon_vma != |
| 228 | (void *)page->mapping - PAGE_MAPPING_ANON) |
| 229 | return -EFAULT; |
| 230 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { |
Hugh Dickins | ee498ed | 2005-11-21 21:32:18 -0800 | [diff] [blame] | 231 | if (!vma->vm_file || |
| 232 | vma->vm_file->f_mapping != page->mapping) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 233 | return -EFAULT; |
| 234 | } else |
| 235 | return -EFAULT; |
| 236 | return vma_address(page, vma); |
| 237 | } |
| 238 | |
| 239 | /* |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 240 | * Check that @page is mapped at @address into @mm. |
| 241 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 242 | * On success returns with pte mapped and locked. |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 243 | */ |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 244 | pte_t *page_check_address(struct page *page, struct mm_struct *mm, |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 245 | unsigned long address, spinlock_t **ptlp) |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 246 | { |
| 247 | pgd_t *pgd; |
| 248 | pud_t *pud; |
| 249 | pmd_t *pmd; |
| 250 | pte_t *pte; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 251 | spinlock_t *ptl; |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 252 | |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 253 | pgd = pgd_offset(mm, address); |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 254 | if (!pgd_present(*pgd)) |
| 255 | return NULL; |
| 256 | |
| 257 | pud = pud_offset(pgd, address); |
| 258 | if (!pud_present(*pud)) |
| 259 | return NULL; |
| 260 | |
| 261 | pmd = pmd_offset(pud, address); |
| 262 | if (!pmd_present(*pmd)) |
| 263 | return NULL; |
| 264 | |
| 265 | pte = pte_offset_map(pmd, address); |
| 266 | /* Make a quick check before getting the lock */ |
| 267 | if (!pte_present(*pte)) { |
| 268 | pte_unmap(pte); |
| 269 | return NULL; |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 270 | } |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 271 | |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 272 | ptl = pte_lockptr(mm, pmd); |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 273 | spin_lock(ptl); |
| 274 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { |
| 275 | *ptlp = ptl; |
| 276 | return pte; |
| 277 | } |
| 278 | pte_unmap_unlock(pte, ptl); |
| 279 | return NULL; |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 280 | } |
| 281 | |
| 282 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 283 | * Subfunctions of page_referenced: page_referenced_one called |
| 284 | * repeatedly from either page_referenced_anon or page_referenced_file. |
| 285 | */ |
| 286 | static int page_referenced_one(struct page *page, |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 287 | struct vm_area_struct *vma, unsigned int *mapcount) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 288 | { |
| 289 | struct mm_struct *mm = vma->vm_mm; |
| 290 | unsigned long address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 291 | pte_t *pte; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 292 | spinlock_t *ptl; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 293 | int referenced = 0; |
| 294 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | address = vma_address(page, vma); |
| 296 | if (address == -EFAULT) |
| 297 | goto out; |
| 298 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 299 | pte = page_check_address(page, mm, address, &ptl); |
| 300 | if (!pte) |
| 301 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 302 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 303 | if (ptep_clear_flush_young(vma, address, pte)) |
| 304 | referenced++; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 305 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 306 | /* Pretend the page is referenced if the task has the |
| 307 | swap token and is in the middle of a page fault. */ |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 308 | if (mm != current->mm && has_swap_token(mm) && |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 309 | rwsem_is_locked(&mm->mmap_sem)) |
| 310 | referenced++; |
| 311 | |
| 312 | (*mapcount)--; |
| 313 | pte_unmap_unlock(pte, ptl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 314 | out: |
| 315 | return referenced; |
| 316 | } |
| 317 | |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 318 | static int page_referenced_anon(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 319 | { |
| 320 | unsigned int mapcount; |
| 321 | struct anon_vma *anon_vma; |
| 322 | struct vm_area_struct *vma; |
| 323 | int referenced = 0; |
| 324 | |
| 325 | anon_vma = page_lock_anon_vma(page); |
| 326 | if (!anon_vma) |
| 327 | return referenced; |
| 328 | |
| 329 | mapcount = page_mapcount(page); |
| 330 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 331 | referenced += page_referenced_one(page, vma, &mapcount); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 332 | if (!mapcount) |
| 333 | break; |
| 334 | } |
| 335 | spin_unlock(&anon_vma->lock); |
| 336 | return referenced; |
| 337 | } |
| 338 | |
| 339 | /** |
| 340 | * page_referenced_file - referenced check for object-based rmap |
| 341 | * @page: the page we're checking references on. |
| 342 | * |
| 343 | * For an object-based mapped page, find all the places it is mapped and |
| 344 | * check/clear the referenced flag. This is done by following the page->mapping |
| 345 | * pointer, then walking the chain of vmas it holds. It returns the number |
| 346 | * of references it found. |
| 347 | * |
| 348 | * This function is only called from page_referenced for object-based pages. |
| 349 | */ |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 350 | static int page_referenced_file(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 351 | { |
| 352 | unsigned int mapcount; |
| 353 | struct address_space *mapping = page->mapping; |
| 354 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 355 | struct vm_area_struct *vma; |
| 356 | struct prio_tree_iter iter; |
| 357 | int referenced = 0; |
| 358 | |
| 359 | /* |
| 360 | * The caller's checks on page->mapping and !PageAnon have made |
| 361 | * sure that this is a file page: the check for page->mapping |
| 362 | * excludes the case just before it gets set on an anon page. |
| 363 | */ |
| 364 | BUG_ON(PageAnon(page)); |
| 365 | |
| 366 | /* |
| 367 | * The page lock not only makes sure that page->mapping cannot |
| 368 | * suddenly be NULLified by truncation, it makes sure that the |
| 369 | * structure at mapping cannot be freed and reused yet, |
| 370 | * so we can safely take mapping->i_mmap_lock. |
| 371 | */ |
| 372 | BUG_ON(!PageLocked(page)); |
| 373 | |
| 374 | spin_lock(&mapping->i_mmap_lock); |
| 375 | |
| 376 | /* |
| 377 | * i_mmap_lock does not stabilize mapcount at all, but mapcount |
| 378 | * is more likely to be accurate if we note it after spinning. |
| 379 | */ |
| 380 | mapcount = page_mapcount(page); |
| 381 | |
| 382 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
| 383 | if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) |
| 384 | == (VM_LOCKED|VM_MAYSHARE)) { |
| 385 | referenced++; |
| 386 | break; |
| 387 | } |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 388 | referenced += page_referenced_one(page, vma, &mapcount); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 389 | if (!mapcount) |
| 390 | break; |
| 391 | } |
| 392 | |
| 393 | spin_unlock(&mapping->i_mmap_lock); |
| 394 | return referenced; |
| 395 | } |
| 396 | |
| 397 | /** |
| 398 | * page_referenced - test if the page was referenced |
| 399 | * @page: the page to test |
| 400 | * @is_locked: caller holds lock on the page |
| 401 | * |
| 402 | * Quick test_and_clear_referenced for all mappings to a page, |
| 403 | * returns the number of ptes which referenced the page. |
| 404 | */ |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 405 | int page_referenced(struct page *page, int is_locked) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 406 | { |
| 407 | int referenced = 0; |
| 408 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 409 | if (page_test_and_clear_young(page)) |
| 410 | referenced++; |
| 411 | |
| 412 | if (TestClearPageReferenced(page)) |
| 413 | referenced++; |
| 414 | |
| 415 | if (page_mapped(page) && page->mapping) { |
| 416 | if (PageAnon(page)) |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 417 | referenced += page_referenced_anon(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 418 | else if (is_locked) |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 419 | referenced += page_referenced_file(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 420 | else if (TestSetPageLocked(page)) |
| 421 | referenced++; |
| 422 | else { |
| 423 | if (page->mapping) |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 424 | referenced += page_referenced_file(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 425 | unlock_page(page); |
| 426 | } |
| 427 | } |
| 428 | return referenced; |
| 429 | } |
| 430 | |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 431 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) |
| 432 | { |
| 433 | struct mm_struct *mm = vma->vm_mm; |
| 434 | unsigned long address; |
| 435 | pte_t *pte, entry; |
| 436 | spinlock_t *ptl; |
| 437 | int ret = 0; |
| 438 | |
| 439 | address = vma_address(page, vma); |
| 440 | if (address == -EFAULT) |
| 441 | goto out; |
| 442 | |
| 443 | pte = page_check_address(page, mm, address, &ptl); |
| 444 | if (!pte) |
| 445 | goto out; |
| 446 | |
| 447 | if (!pte_dirty(*pte) && !pte_write(*pte)) |
| 448 | goto unlock; |
| 449 | |
| 450 | entry = ptep_get_and_clear(mm, address, pte); |
| 451 | entry = pte_mkclean(entry); |
| 452 | entry = pte_wrprotect(entry); |
| 453 | ptep_establish(vma, address, pte, entry); |
| 454 | lazy_mmu_prot_update(entry); |
| 455 | ret = 1; |
| 456 | |
| 457 | unlock: |
| 458 | pte_unmap_unlock(pte, ptl); |
| 459 | out: |
| 460 | return ret; |
| 461 | } |
| 462 | |
| 463 | static int page_mkclean_file(struct address_space *mapping, struct page *page) |
| 464 | { |
| 465 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 466 | struct vm_area_struct *vma; |
| 467 | struct prio_tree_iter iter; |
| 468 | int ret = 0; |
| 469 | |
| 470 | BUG_ON(PageAnon(page)); |
| 471 | |
| 472 | spin_lock(&mapping->i_mmap_lock); |
| 473 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
| 474 | if (vma->vm_flags & VM_SHARED) |
| 475 | ret += page_mkclean_one(page, vma); |
| 476 | } |
| 477 | spin_unlock(&mapping->i_mmap_lock); |
| 478 | return ret; |
| 479 | } |
| 480 | |
| 481 | int page_mkclean(struct page *page) |
| 482 | { |
| 483 | int ret = 0; |
| 484 | |
| 485 | BUG_ON(!PageLocked(page)); |
| 486 | |
| 487 | if (page_mapped(page)) { |
| 488 | struct address_space *mapping = page_mapping(page); |
| 489 | if (mapping) |
| 490 | ret = page_mkclean_file(mapping, page); |
| 491 | } |
| 492 | |
| 493 | return ret; |
| 494 | } |
| 495 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 496 | /** |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 497 | * page_set_anon_rmap - setup new anonymous rmap |
| 498 | * @page: the page to add the mapping to |
| 499 | * @vma: the vm area in which the mapping is added |
| 500 | * @address: the user virtual address mapped |
| 501 | */ |
| 502 | static void __page_set_anon_rmap(struct page *page, |
| 503 | struct vm_area_struct *vma, unsigned long address) |
| 504 | { |
| 505 | struct anon_vma *anon_vma = vma->anon_vma; |
| 506 | |
| 507 | BUG_ON(!anon_vma); |
| 508 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
| 509 | page->mapping = (struct address_space *) anon_vma; |
| 510 | |
| 511 | page->index = linear_page_index(vma, address); |
| 512 | |
Nick Piggin | a74609f | 2006-01-06 00:11:20 -0800 | [diff] [blame] | 513 | /* |
| 514 | * nr_mapped state can be updated without turning off |
| 515 | * interrupts because it is not modified via interrupt. |
| 516 | */ |
Christoph Lameter | f3dbd34 | 2006-06-30 01:55:36 -0700 | [diff] [blame] | 517 | __inc_zone_page_state(page, NR_ANON_PAGES); |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 518 | } |
| 519 | |
| 520 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | * page_add_anon_rmap - add pte mapping to an anonymous page |
| 522 | * @page: the page to add the mapping to |
| 523 | * @vma: the vm area in which the mapping is added |
| 524 | * @address: the user virtual address mapped |
| 525 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 526 | * The caller needs to hold the pte lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 527 | */ |
| 528 | void page_add_anon_rmap(struct page *page, |
| 529 | struct vm_area_struct *vma, unsigned long address) |
| 530 | { |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 531 | if (atomic_inc_and_test(&page->_mapcount)) |
| 532 | __page_set_anon_rmap(page, vma, address); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 533 | /* else checking page index and mapping is racy */ |
| 534 | } |
| 535 | |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 536 | /* |
| 537 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
| 538 | * @page: the page to add the mapping to |
| 539 | * @vma: the vm area in which the mapping is added |
| 540 | * @address: the user virtual address mapped |
| 541 | * |
| 542 | * Same as page_add_anon_rmap but must only be called on *new* pages. |
| 543 | * This means the inc-and-test can be bypassed. |
| 544 | */ |
| 545 | void page_add_new_anon_rmap(struct page *page, |
| 546 | struct vm_area_struct *vma, unsigned long address) |
| 547 | { |
| 548 | atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ |
| 549 | __page_set_anon_rmap(page, vma, address); |
| 550 | } |
| 551 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 552 | /** |
| 553 | * page_add_file_rmap - add pte mapping to a file page |
| 554 | * @page: the page to add the mapping to |
| 555 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 556 | * The caller needs to hold the pte lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 557 | */ |
| 558 | void page_add_file_rmap(struct page *page) |
| 559 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 560 | if (atomic_inc_and_test(&page->_mapcount)) |
Christoph Lameter | 65ba55f | 2006-06-30 01:55:34 -0700 | [diff] [blame] | 561 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 562 | } |
| 563 | |
| 564 | /** |
| 565 | * page_remove_rmap - take down pte mapping from a page |
| 566 | * @page: page to remove mapping from |
| 567 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 568 | * The caller needs to hold the pte lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 569 | */ |
| 570 | void page_remove_rmap(struct page *page) |
| 571 | { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 572 | if (atomic_add_negative(-1, &page->_mapcount)) { |
Nick Piggin | b7ab795 | 2006-03-22 00:08:42 -0800 | [diff] [blame] | 573 | if (unlikely(page_mapcount(page) < 0)) { |
Dave Jones | ef2bf0d | 2006-01-08 01:01:00 -0800 | [diff] [blame] | 574 | printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); |
| 575 | printk (KERN_EMERG " page->flags = %lx\n", page->flags); |
| 576 | printk (KERN_EMERG " page->count = %x\n", page_count(page)); |
| 577 | printk (KERN_EMERG " page->mapping = %p\n", page->mapping); |
Dave Jones | b16bc64 | 2006-10-11 01:21:27 -0700 | [diff] [blame] | 578 | BUG(); |
Dave Jones | ef2bf0d | 2006-01-08 01:01:00 -0800 | [diff] [blame] | 579 | } |
Dave Jones | b16bc64 | 2006-10-11 01:21:27 -0700 | [diff] [blame] | 580 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 581 | /* |
| 582 | * It would be tidy to reset the PageAnon mapping here, |
| 583 | * but that might overwrite a racing page_add_anon_rmap |
| 584 | * which increments mapcount after us but sets mapping |
| 585 | * before us: so leave the reset to free_hot_cold_page, |
| 586 | * and remember that it's only reliable while mapped. |
| 587 | * Leaving it set also helps swapoff to reinstate ptes |
| 588 | * faster for those pages still in swapcache. |
| 589 | */ |
| 590 | if (page_test_and_clear_dirty(page)) |
| 591 | set_page_dirty(page); |
Christoph Lameter | f3dbd34 | 2006-06-30 01:55:36 -0700 | [diff] [blame] | 592 | __dec_zone_page_state(page, |
| 593 | PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 594 | } |
| 595 | } |
| 596 | |
| 597 | /* |
| 598 | * Subfunctions of try_to_unmap: try_to_unmap_one called |
| 599 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. |
| 600 | */ |
Christoph Lameter | a48d07a | 2006-02-01 03:05:38 -0800 | [diff] [blame] | 601 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 602 | int migration) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 603 | { |
| 604 | struct mm_struct *mm = vma->vm_mm; |
| 605 | unsigned long address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 606 | pte_t *pte; |
| 607 | pte_t pteval; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 608 | spinlock_t *ptl; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 609 | int ret = SWAP_AGAIN; |
| 610 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 611 | address = vma_address(page, vma); |
| 612 | if (address == -EFAULT) |
| 613 | goto out; |
| 614 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 615 | pte = page_check_address(page, mm, address, &ptl); |
| 616 | if (!pte) |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 617 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 618 | |
| 619 | /* |
| 620 | * If the page is mlock()d, we cannot swap it out. |
| 621 | * If it's recently referenced (perhaps page_referenced |
| 622 | * skipped over this mm) then we should reactivate it. |
| 623 | */ |
Christoph Lameter | e6a1530 | 2006-06-25 05:46:49 -0700 | [diff] [blame] | 624 | if (!migration && ((vma->vm_flags & VM_LOCKED) || |
| 625 | (ptep_clear_flush_young(vma, address, pte)))) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 626 | ret = SWAP_FAIL; |
| 627 | goto out_unmap; |
| 628 | } |
| 629 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 630 | /* Nuke the page table entry. */ |
| 631 | flush_cache_page(vma, address, page_to_pfn(page)); |
| 632 | pteval = ptep_clear_flush(vma, address, pte); |
| 633 | |
| 634 | /* Move the dirty bit to the physical page now the pte is gone. */ |
| 635 | if (pte_dirty(pteval)) |
| 636 | set_page_dirty(page); |
| 637 | |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 638 | /* Update high watermark before we lower rss */ |
| 639 | update_hiwater_rss(mm); |
| 640 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 641 | if (PageAnon(page)) { |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 642 | swp_entry_t entry = { .val = page_private(page) }; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 643 | |
| 644 | if (PageSwapCache(page)) { |
| 645 | /* |
| 646 | * Store the swap location in the pte. |
| 647 | * See handle_pte_fault() ... |
| 648 | */ |
| 649 | swap_duplicate(entry); |
| 650 | if (list_empty(&mm->mmlist)) { |
| 651 | spin_lock(&mmlist_lock); |
| 652 | if (list_empty(&mm->mmlist)) |
| 653 | list_add(&mm->mmlist, &init_mm.mmlist); |
| 654 | spin_unlock(&mmlist_lock); |
| 655 | } |
Christoph Lameter | 442c913 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 656 | dec_mm_counter(mm, anon_rss); |
Christoph Lameter | 04e62a2 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 657 | #ifdef CONFIG_MIGRATION |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 658 | } else { |
| 659 | /* |
| 660 | * Store the pfn of the page in a special migration |
| 661 | * pte. do_swap_page() will wait until the migration |
| 662 | * pte is removed and then restart fault handling. |
| 663 | */ |
| 664 | BUG_ON(!migration); |
| 665 | entry = make_migration_entry(page, pte_write(pteval)); |
Christoph Lameter | 04e62a2 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 666 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 667 | } |
| 668 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
| 669 | BUG_ON(pte_file(*pte)); |
Hugh Dickins | 4294621 | 2005-10-29 18:16:05 -0700 | [diff] [blame] | 670 | } else |
Christoph Lameter | 04e62a2 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 671 | #ifdef CONFIG_MIGRATION |
| 672 | if (migration) { |
| 673 | /* Establish migration entry for a file page */ |
| 674 | swp_entry_t entry; |
| 675 | entry = make_migration_entry(page, pte_write(pteval)); |
| 676 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
| 677 | } else |
| 678 | #endif |
Hugh Dickins | 4294621 | 2005-10-29 18:16:05 -0700 | [diff] [blame] | 679 | dec_mm_counter(mm, file_rss); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 680 | |
Christoph Lameter | 04e62a2 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 681 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 682 | page_remove_rmap(page); |
| 683 | page_cache_release(page); |
| 684 | |
| 685 | out_unmap: |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 686 | pte_unmap_unlock(pte, ptl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 687 | out: |
| 688 | return ret; |
| 689 | } |
| 690 | |
| 691 | /* |
| 692 | * objrmap doesn't work for nonlinear VMAs because the assumption that |
| 693 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. |
| 694 | * Consequently, given a particular page and its ->index, we cannot locate the |
| 695 | * ptes which are mapping that page without an exhaustive linear search. |
| 696 | * |
| 697 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which |
| 698 | * maps the file to which the target page belongs. The ->vm_private_data field |
| 699 | * holds the current cursor into that scan. Successive searches will circulate |
| 700 | * around the vma's virtual address space. |
| 701 | * |
| 702 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, |
| 703 | * more scanning pressure is placed against them as well. Eventually pages |
| 704 | * will become fully unmapped and are eligible for eviction. |
| 705 | * |
| 706 | * For very sparsely populated VMAs this is a little inefficient - chances are |
| 707 | * there there won't be many ptes located within the scan cluster. In this case |
| 708 | * maybe we could scan further - to the end of the pte page, perhaps. |
| 709 | */ |
| 710 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) |
| 711 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) |
| 712 | |
| 713 | static void try_to_unmap_cluster(unsigned long cursor, |
| 714 | unsigned int *mapcount, struct vm_area_struct *vma) |
| 715 | { |
| 716 | struct mm_struct *mm = vma->vm_mm; |
| 717 | pgd_t *pgd; |
| 718 | pud_t *pud; |
| 719 | pmd_t *pmd; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 720 | pte_t *pte; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 721 | pte_t pteval; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 722 | spinlock_t *ptl; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 723 | struct page *page; |
| 724 | unsigned long address; |
| 725 | unsigned long end; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 726 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 727 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
| 728 | end = address + CLUSTER_SIZE; |
| 729 | if (address < vma->vm_start) |
| 730 | address = vma->vm_start; |
| 731 | if (end > vma->vm_end) |
| 732 | end = vma->vm_end; |
| 733 | |
| 734 | pgd = pgd_offset(mm, address); |
| 735 | if (!pgd_present(*pgd)) |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 736 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 737 | |
| 738 | pud = pud_offset(pgd, address); |
| 739 | if (!pud_present(*pud)) |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 740 | return; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 741 | |
| 742 | pmd = pmd_offset(pud, address); |
| 743 | if (!pmd_present(*pmd)) |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 744 | return; |
| 745 | |
| 746 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 747 | |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 748 | /* Update high watermark before we lower rss */ |
| 749 | update_hiwater_rss(mm); |
| 750 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 751 | for (; address < end; pte++, address += PAGE_SIZE) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 752 | if (!pte_present(*pte)) |
| 753 | continue; |
Linus Torvalds | 6aab341 | 2005-11-28 14:34:23 -0800 | [diff] [blame] | 754 | page = vm_normal_page(vma, address, *pte); |
| 755 | BUG_ON(!page || PageAnon(page)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 756 | |
| 757 | if (ptep_clear_flush_young(vma, address, pte)) |
| 758 | continue; |
| 759 | |
| 760 | /* Nuke the page table entry. */ |
Ben Collins | eca3513 | 2005-11-29 11:45:26 -0800 | [diff] [blame] | 761 | flush_cache_page(vma, address, pte_pfn(*pte)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 762 | pteval = ptep_clear_flush(vma, address, pte); |
| 763 | |
| 764 | /* If nonlinear, store the file page offset in the pte. */ |
| 765 | if (page->index != linear_page_index(vma, address)) |
| 766 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); |
| 767 | |
| 768 | /* Move the dirty bit to the physical page now the pte is gone. */ |
| 769 | if (pte_dirty(pteval)) |
| 770 | set_page_dirty(page); |
| 771 | |
| 772 | page_remove_rmap(page); |
| 773 | page_cache_release(page); |
Hugh Dickins | 4294621 | 2005-10-29 18:16:05 -0700 | [diff] [blame] | 774 | dec_mm_counter(mm, file_rss); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 775 | (*mapcount)--; |
| 776 | } |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 777 | pte_unmap_unlock(pte - 1, ptl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 778 | } |
| 779 | |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 780 | static int try_to_unmap_anon(struct page *page, int migration) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 781 | { |
| 782 | struct anon_vma *anon_vma; |
| 783 | struct vm_area_struct *vma; |
| 784 | int ret = SWAP_AGAIN; |
| 785 | |
| 786 | anon_vma = page_lock_anon_vma(page); |
| 787 | if (!anon_vma) |
| 788 | return ret; |
| 789 | |
| 790 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 791 | ret = try_to_unmap_one(page, vma, migration); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 792 | if (ret == SWAP_FAIL || !page_mapped(page)) |
| 793 | break; |
| 794 | } |
| 795 | spin_unlock(&anon_vma->lock); |
| 796 | return ret; |
| 797 | } |
| 798 | |
| 799 | /** |
| 800 | * try_to_unmap_file - unmap file page using the object-based rmap method |
| 801 | * @page: the page to unmap |
| 802 | * |
| 803 | * Find all the mappings of a page using the mapping pointer and the vma chains |
| 804 | * contained in the address_space struct it points to. |
| 805 | * |
| 806 | * This function is only called from try_to_unmap for object-based pages. |
| 807 | */ |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 808 | static int try_to_unmap_file(struct page *page, int migration) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 809 | { |
| 810 | struct address_space *mapping = page->mapping; |
| 811 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 812 | struct vm_area_struct *vma; |
| 813 | struct prio_tree_iter iter; |
| 814 | int ret = SWAP_AGAIN; |
| 815 | unsigned long cursor; |
| 816 | unsigned long max_nl_cursor = 0; |
| 817 | unsigned long max_nl_size = 0; |
| 818 | unsigned int mapcount; |
| 819 | |
| 820 | spin_lock(&mapping->i_mmap_lock); |
| 821 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 822 | ret = try_to_unmap_one(page, vma, migration); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 823 | if (ret == SWAP_FAIL || !page_mapped(page)) |
| 824 | goto out; |
| 825 | } |
| 826 | |
| 827 | if (list_empty(&mapping->i_mmap_nonlinear)) |
| 828 | goto out; |
| 829 | |
| 830 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
| 831 | shared.vm_set.list) { |
Christoph Lameter | e6a1530 | 2006-06-25 05:46:49 -0700 | [diff] [blame] | 832 | if ((vma->vm_flags & VM_LOCKED) && !migration) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 833 | continue; |
| 834 | cursor = (unsigned long) vma->vm_private_data; |
| 835 | if (cursor > max_nl_cursor) |
| 836 | max_nl_cursor = cursor; |
| 837 | cursor = vma->vm_end - vma->vm_start; |
| 838 | if (cursor > max_nl_size) |
| 839 | max_nl_size = cursor; |
| 840 | } |
| 841 | |
| 842 | if (max_nl_size == 0) { /* any nonlinears locked or reserved */ |
| 843 | ret = SWAP_FAIL; |
| 844 | goto out; |
| 845 | } |
| 846 | |
| 847 | /* |
| 848 | * We don't try to search for this page in the nonlinear vmas, |
| 849 | * and page_referenced wouldn't have found it anyway. Instead |
| 850 | * just walk the nonlinear vmas trying to age and unmap some. |
| 851 | * The mapcount of the page we came in with is irrelevant, |
| 852 | * but even so use it as a guide to how hard we should try? |
| 853 | */ |
| 854 | mapcount = page_mapcount(page); |
| 855 | if (!mapcount) |
| 856 | goto out; |
| 857 | cond_resched_lock(&mapping->i_mmap_lock); |
| 858 | |
| 859 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; |
| 860 | if (max_nl_cursor == 0) |
| 861 | max_nl_cursor = CLUSTER_SIZE; |
| 862 | |
| 863 | do { |
| 864 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
| 865 | shared.vm_set.list) { |
Christoph Lameter | e6a1530 | 2006-06-25 05:46:49 -0700 | [diff] [blame] | 866 | if ((vma->vm_flags & VM_LOCKED) && !migration) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 867 | continue; |
| 868 | cursor = (unsigned long) vma->vm_private_data; |
Hugh Dickins | 839b968 | 2005-09-03 15:54:43 -0700 | [diff] [blame] | 869 | while ( cursor < max_nl_cursor && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 870 | cursor < vma->vm_end - vma->vm_start) { |
| 871 | try_to_unmap_cluster(cursor, &mapcount, vma); |
| 872 | cursor += CLUSTER_SIZE; |
| 873 | vma->vm_private_data = (void *) cursor; |
| 874 | if ((int)mapcount <= 0) |
| 875 | goto out; |
| 876 | } |
| 877 | vma->vm_private_data = (void *) max_nl_cursor; |
| 878 | } |
| 879 | cond_resched_lock(&mapping->i_mmap_lock); |
| 880 | max_nl_cursor += CLUSTER_SIZE; |
| 881 | } while (max_nl_cursor <= max_nl_size); |
| 882 | |
| 883 | /* |
| 884 | * Don't loop forever (perhaps all the remaining pages are |
| 885 | * in locked vmas). Reset cursor on all unreserved nonlinear |
| 886 | * vmas, now forgetting on which ones it had fallen behind. |
| 887 | */ |
Hugh Dickins | 101d2be | 2005-11-21 21:32:16 -0800 | [diff] [blame] | 888 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
| 889 | vma->vm_private_data = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 890 | out: |
| 891 | spin_unlock(&mapping->i_mmap_lock); |
| 892 | return ret; |
| 893 | } |
| 894 | |
| 895 | /** |
| 896 | * try_to_unmap - try to remove all page table mappings to a page |
| 897 | * @page: the page to get unmapped |
| 898 | * |
| 899 | * Tries to remove all the page table entries which are mapping this |
| 900 | * page, used in the pageout path. Caller must hold the page lock. |
| 901 | * Return values are: |
| 902 | * |
| 903 | * SWAP_SUCCESS - we succeeded in removing all mappings |
| 904 | * SWAP_AGAIN - we missed a mapping, try again later |
| 905 | * SWAP_FAIL - the page is unswappable |
| 906 | */ |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 907 | int try_to_unmap(struct page *page, int migration) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 908 | { |
| 909 | int ret; |
| 910 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 911 | BUG_ON(!PageLocked(page)); |
| 912 | |
| 913 | if (PageAnon(page)) |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 914 | ret = try_to_unmap_anon(page, migration); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 915 | else |
Christoph Lameter | 7352349 | 2006-06-23 02:03:27 -0700 | [diff] [blame] | 916 | ret = try_to_unmap_file(page, migration); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 917 | |
| 918 | if (!page_mapped(page)) |
| 919 | ret = SWAP_SUCCESS; |
| 920 | return ret; |
| 921 | } |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 922 | |