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 |
Hugh Dickins | 98f3260 | 2009-05-21 20:33:58 +0100 | [diff] [blame] | 17 | * Contributions by Hugh Dickins 2003, 2004 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 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) |
Andi Kleen | 6a46079 | 2009-09-16 11:50:15 +0200 | [diff] [blame] | 39 | * |
| 40 | * (code doesn't rely on that order so it could be switched around) |
| 41 | * ->tasklist_lock |
| 42 | * anon_vma->lock (memory_failure, collect_procs_anon) |
| 43 | * pte map lock |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 44 | */ |
| 45 | |
| 46 | #include <linux/mm.h> |
| 47 | #include <linux/pagemap.h> |
| 48 | #include <linux/swap.h> |
| 49 | #include <linux/swapops.h> |
| 50 | #include <linux/slab.h> |
| 51 | #include <linux/init.h> |
| 52 | #include <linux/rmap.h> |
| 53 | #include <linux/rcupdate.h> |
Christoph Lameter | a48d07a | 2006-02-01 03:05:38 -0800 | [diff] [blame] | 54 | #include <linux/module.h> |
Balbir Singh | 8a9f3cc | 2008-02-07 00:13:53 -0800 | [diff] [blame] | 55 | #include <linux/memcontrol.h> |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 56 | #include <linux/mmu_notifier.h> |
KOSAKI Motohiro | 64cdd54 | 2009-01-06 14:39:16 -0800 | [diff] [blame] | 57 | #include <linux/migrate.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 58 | |
| 59 | #include <asm/tlbflush.h> |
| 60 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 61 | #include "internal.h" |
| 62 | |
Adrian Bunk | fdd2e5f | 2008-10-18 20:28:38 -0700 | [diff] [blame] | 63 | static struct kmem_cache *anon_vma_cachep; |
| 64 | |
| 65 | static inline struct anon_vma *anon_vma_alloc(void) |
| 66 | { |
| 67 | return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); |
| 68 | } |
| 69 | |
| 70 | static inline void anon_vma_free(struct anon_vma *anon_vma) |
| 71 | { |
| 72 | kmem_cache_free(anon_vma_cachep, anon_vma); |
| 73 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 74 | |
Linus Torvalds | d9d332e | 2008-10-19 10:32:20 -0700 | [diff] [blame] | 75 | /** |
| 76 | * anon_vma_prepare - attach an anon_vma to a memory region |
| 77 | * @vma: the memory region in question |
| 78 | * |
| 79 | * This makes sure the memory mapping described by 'vma' has |
| 80 | * an 'anon_vma' attached to it, so that we can associate the |
| 81 | * anonymous pages mapped into it with that anon_vma. |
| 82 | * |
| 83 | * The common case will be that we already have one, but if |
| 84 | * if not we either need to find an adjacent mapping that we |
| 85 | * can re-use the anon_vma from (very common when the only |
| 86 | * reason for splitting a vma has been mprotect()), or we |
| 87 | * allocate a new one. |
| 88 | * |
| 89 | * Anon-vma allocations are very subtle, because we may have |
| 90 | * optimistically looked up an anon_vma in page_lock_anon_vma() |
| 91 | * and that may actually touch the spinlock even in the newly |
| 92 | * allocated vma (it depends on RCU to make sure that the |
| 93 | * anon_vma isn't actually destroyed). |
| 94 | * |
| 95 | * As a result, we need to do proper anon_vma locking even |
| 96 | * for the new allocation. At the same time, we do not want |
| 97 | * to do any locking for the common case of already having |
| 98 | * an anon_vma. |
| 99 | * |
| 100 | * This must be called with the mmap_sem held for reading. |
| 101 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | int anon_vma_prepare(struct vm_area_struct *vma) |
| 103 | { |
| 104 | struct anon_vma *anon_vma = vma->anon_vma; |
| 105 | |
| 106 | might_sleep(); |
| 107 | if (unlikely(!anon_vma)) { |
| 108 | struct mm_struct *mm = vma->vm_mm; |
Linus Torvalds | d9d332e | 2008-10-19 10:32:20 -0700 | [diff] [blame] | 109 | struct anon_vma *allocated; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | |
| 111 | anon_vma = find_mergeable_anon_vma(vma); |
Linus Torvalds | d9d332e | 2008-10-19 10:32:20 -0700 | [diff] [blame] | 112 | allocated = NULL; |
| 113 | if (!anon_vma) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 114 | anon_vma = anon_vma_alloc(); |
| 115 | if (unlikely(!anon_vma)) |
| 116 | return -ENOMEM; |
| 117 | allocated = anon_vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 118 | } |
Linus Torvalds | d9d332e | 2008-10-19 10:32:20 -0700 | [diff] [blame] | 119 | spin_lock(&anon_vma->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 120 | |
| 121 | /* page_table_lock to protect against threads */ |
| 122 | spin_lock(&mm->page_table_lock); |
| 123 | if (likely(!vma->anon_vma)) { |
| 124 | vma->anon_vma = anon_vma; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 125 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 126 | allocated = NULL; |
| 127 | } |
| 128 | spin_unlock(&mm->page_table_lock); |
| 129 | |
Linus Torvalds | d9d332e | 2008-10-19 10:32:20 -0700 | [diff] [blame] | 130 | spin_unlock(&anon_vma->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | if (unlikely(allocated)) |
| 132 | anon_vma_free(allocated); |
| 133 | } |
| 134 | return 0; |
| 135 | } |
| 136 | |
| 137 | void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) |
| 138 | { |
| 139 | BUG_ON(vma->anon_vma != next->anon_vma); |
| 140 | list_del(&next->anon_vma_node); |
| 141 | } |
| 142 | |
| 143 | void __anon_vma_link(struct vm_area_struct *vma) |
| 144 | { |
| 145 | struct anon_vma *anon_vma = vma->anon_vma; |
| 146 | |
Hugh Dickins | 30acbab | 2007-06-27 14:09:53 -0700 | [diff] [blame] | 147 | if (anon_vma) |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 148 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | } |
| 150 | |
| 151 | void anon_vma_link(struct vm_area_struct *vma) |
| 152 | { |
| 153 | struct anon_vma *anon_vma = vma->anon_vma; |
| 154 | |
| 155 | if (anon_vma) { |
| 156 | spin_lock(&anon_vma->lock); |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 157 | list_add_tail(&vma->anon_vma_node, &anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 158 | spin_unlock(&anon_vma->lock); |
| 159 | } |
| 160 | } |
| 161 | |
| 162 | void anon_vma_unlink(struct vm_area_struct *vma) |
| 163 | { |
| 164 | struct anon_vma *anon_vma = vma->anon_vma; |
| 165 | int empty; |
| 166 | |
| 167 | if (!anon_vma) |
| 168 | return; |
| 169 | |
| 170 | spin_lock(&anon_vma->lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 171 | list_del(&vma->anon_vma_node); |
| 172 | |
| 173 | /* We must garbage collect the anon_vma if it's empty */ |
| 174 | empty = list_empty(&anon_vma->head); |
| 175 | spin_unlock(&anon_vma->lock); |
| 176 | |
| 177 | if (empty) |
| 178 | anon_vma_free(anon_vma); |
| 179 | } |
| 180 | |
Alexey Dobriyan | 51cc506 | 2008-07-25 19:45:34 -0700 | [diff] [blame] | 181 | static void anon_vma_ctor(void *data) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 182 | { |
Christoph Lameter | a35afb8 | 2007-05-16 22:10:57 -0700 | [diff] [blame] | 183 | struct anon_vma *anon_vma = data; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 184 | |
Christoph Lameter | a35afb8 | 2007-05-16 22:10:57 -0700 | [diff] [blame] | 185 | spin_lock_init(&anon_vma->lock); |
| 186 | INIT_LIST_HEAD(&anon_vma->head); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 187 | } |
| 188 | |
| 189 | void __init anon_vma_init(void) |
| 190 | { |
| 191 | anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), |
Paul Mundt | 20c2df8 | 2007-07-20 10:11:58 +0900 | [diff] [blame] | 192 | 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 193 | } |
| 194 | |
| 195 | /* |
| 196 | * Getting a lock on a stable anon_vma from a page off the LRU is |
| 197 | * tricky: page_lock_anon_vma rely on RCU to guard against the races. |
| 198 | */ |
Andi Kleen | 10be22d | 2009-09-16 11:50:04 +0200 | [diff] [blame] | 199 | struct anon_vma *page_lock_anon_vma(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 200 | { |
Oleg Nesterov | 34bbd70 | 2007-02-28 20:13:49 -0800 | [diff] [blame] | 201 | struct anon_vma *anon_vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 202 | unsigned long anon_mapping; |
| 203 | |
| 204 | rcu_read_lock(); |
| 205 | anon_mapping = (unsigned long) page->mapping; |
Hugh Dickins | 3ca7b3c | 2009-12-14 17:58:57 -0800 | [diff] [blame] | 206 | if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 207 | goto out; |
| 208 | if (!page_mapped(page)) |
| 209 | goto out; |
| 210 | |
| 211 | anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); |
| 212 | spin_lock(&anon_vma->lock); |
Oleg Nesterov | 34bbd70 | 2007-02-28 20:13:49 -0800 | [diff] [blame] | 213 | return anon_vma; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | out: |
| 215 | rcu_read_unlock(); |
Oleg Nesterov | 34bbd70 | 2007-02-28 20:13:49 -0800 | [diff] [blame] | 216 | return NULL; |
| 217 | } |
| 218 | |
Andi Kleen | 10be22d | 2009-09-16 11:50:04 +0200 | [diff] [blame] | 219 | void page_unlock_anon_vma(struct anon_vma *anon_vma) |
Oleg Nesterov | 34bbd70 | 2007-02-28 20:13:49 -0800 | [diff] [blame] | 220 | { |
| 221 | spin_unlock(&anon_vma->lock); |
| 222 | rcu_read_unlock(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 223 | } |
| 224 | |
| 225 | /* |
Lee Schermerhorn | 3ad33b2 | 2007-11-14 16:59:10 -0800 | [diff] [blame] | 226 | * At what user virtual address is page expected in @vma? |
| 227 | * Returns virtual address or -EFAULT if page's index/offset is not |
| 228 | * within the range mapped the @vma. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 229 | */ |
| 230 | static inline unsigned long |
| 231 | vma_address(struct page *page, struct vm_area_struct *vma) |
| 232 | { |
| 233 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 234 | unsigned long address; |
| 235 | |
| 236 | address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); |
| 237 | if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { |
Lee Schermerhorn | 3ad33b2 | 2007-11-14 16:59:10 -0800 | [diff] [blame] | 238 | /* page should be within @vma mapping range */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | return -EFAULT; |
| 240 | } |
| 241 | return address; |
| 242 | } |
| 243 | |
| 244 | /* |
Huang Shijie | bf89c8c | 2009-10-01 15:44:04 -0700 | [diff] [blame] | 245 | * At what user virtual address is page expected in vma? |
| 246 | * checking that the page matches the vma. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | */ |
| 248 | unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) |
| 249 | { |
| 250 | if (PageAnon(page)) { |
Hugh Dickins | 3ca7b3c | 2009-12-14 17:58:57 -0800 | [diff] [blame] | 251 | if (vma->anon_vma != page_anon_vma(page)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 252 | return -EFAULT; |
| 253 | } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { |
Hugh Dickins | ee498ed | 2005-11-21 21:32:18 -0800 | [diff] [blame] | 254 | if (!vma->vm_file || |
| 255 | vma->vm_file->f_mapping != page->mapping) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 256 | return -EFAULT; |
| 257 | } else |
| 258 | return -EFAULT; |
| 259 | return vma_address(page, vma); |
| 260 | } |
| 261 | |
| 262 | /* |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 263 | * Check that @page is mapped at @address into @mm. |
| 264 | * |
Nick Piggin | 479db0b | 2008-08-20 14:09:18 -0700 | [diff] [blame] | 265 | * If @sync is false, page_check_address may perform a racy check to avoid |
| 266 | * the page table lock when the pte is not present (helpful when reclaiming |
| 267 | * highly shared pages). |
| 268 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 269 | * On success returns with pte mapped and locked. |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 270 | */ |
Carsten Otte | ceffc07 | 2005-06-23 22:05:25 -0700 | [diff] [blame] | 271 | pte_t *page_check_address(struct page *page, struct mm_struct *mm, |
Nick Piggin | 479db0b | 2008-08-20 14:09:18 -0700 | [diff] [blame] | 272 | unsigned long address, spinlock_t **ptlp, int sync) |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 273 | { |
| 274 | pgd_t *pgd; |
| 275 | pud_t *pud; |
| 276 | pmd_t *pmd; |
| 277 | pte_t *pte; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 278 | spinlock_t *ptl; |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 279 | |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 280 | pgd = pgd_offset(mm, address); |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 281 | if (!pgd_present(*pgd)) |
| 282 | return NULL; |
| 283 | |
| 284 | pud = pud_offset(pgd, address); |
| 285 | if (!pud_present(*pud)) |
| 286 | return NULL; |
| 287 | |
| 288 | pmd = pmd_offset(pud, address); |
| 289 | if (!pmd_present(*pmd)) |
| 290 | return NULL; |
| 291 | |
| 292 | pte = pte_offset_map(pmd, address); |
| 293 | /* Make a quick check before getting the lock */ |
Nick Piggin | 479db0b | 2008-08-20 14:09:18 -0700 | [diff] [blame] | 294 | if (!sync && !pte_present(*pte)) { |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 295 | pte_unmap(pte); |
| 296 | return NULL; |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 297 | } |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 298 | |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 299 | ptl = pte_lockptr(mm, pmd); |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 300 | spin_lock(ptl); |
| 301 | if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { |
| 302 | *ptlp = ptl; |
| 303 | return pte; |
| 304 | } |
| 305 | pte_unmap_unlock(pte, ptl); |
| 306 | return NULL; |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 307 | } |
| 308 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 309 | /** |
| 310 | * page_mapped_in_vma - check whether a page is really mapped in a VMA |
| 311 | * @page: the page to test |
| 312 | * @vma: the VMA to test |
| 313 | * |
| 314 | * Returns 1 if the page is mapped into the page tables of the VMA, 0 |
| 315 | * if the page is not mapped into the page tables of this VMA. Only |
| 316 | * valid for normal file or anonymous VMAs. |
| 317 | */ |
Andi Kleen | 6a46079 | 2009-09-16 11:50:15 +0200 | [diff] [blame] | 318 | int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 319 | { |
| 320 | unsigned long address; |
| 321 | pte_t *pte; |
| 322 | spinlock_t *ptl; |
| 323 | |
| 324 | address = vma_address(page, vma); |
| 325 | if (address == -EFAULT) /* out of vma range */ |
| 326 | return 0; |
| 327 | pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); |
| 328 | if (!pte) /* the page is not in this mm */ |
| 329 | return 0; |
| 330 | pte_unmap_unlock(pte, ptl); |
| 331 | |
| 332 | return 1; |
| 333 | } |
| 334 | |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 335 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 336 | * Subfunctions of page_referenced: page_referenced_one called |
| 337 | * repeatedly from either page_referenced_anon or page_referenced_file. |
| 338 | */ |
| 339 | static int page_referenced_one(struct page *page, |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 340 | struct vm_area_struct *vma, |
| 341 | unsigned int *mapcount, |
| 342 | unsigned long *vm_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 343 | { |
| 344 | struct mm_struct *mm = vma->vm_mm; |
| 345 | unsigned long address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 346 | pte_t *pte; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 347 | spinlock_t *ptl; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 348 | int referenced = 0; |
| 349 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 350 | address = vma_address(page, vma); |
| 351 | if (address == -EFAULT) |
| 352 | goto out; |
| 353 | |
Nick Piggin | 479db0b | 2008-08-20 14:09:18 -0700 | [diff] [blame] | 354 | pte = page_check_address(page, mm, address, &ptl, 0); |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 355 | if (!pte) |
| 356 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 357 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 358 | /* |
| 359 | * Don't want to elevate referenced for mlocked page that gets this far, |
| 360 | * in order that it progresses to try_to_unmap and is moved to the |
| 361 | * unevictable list. |
| 362 | */ |
Hugh Dickins | 5a9bbdc | 2008-02-04 22:29:23 -0800 | [diff] [blame] | 363 | if (vma->vm_flags & VM_LOCKED) { |
Hugh Dickins | 5a9bbdc | 2008-02-04 22:29:23 -0800 | [diff] [blame] | 364 | *mapcount = 1; /* break early from loop */ |
Minchan Kim | 03ef83a | 2009-08-26 14:29:23 -0700 | [diff] [blame] | 365 | *vm_flags |= VM_LOCKED; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 366 | goto out_unmap; |
| 367 | } |
| 368 | |
Johannes Weiner | 4917e5d | 2009-01-06 14:39:17 -0800 | [diff] [blame] | 369 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
| 370 | /* |
| 371 | * Don't treat a reference through a sequentially read |
| 372 | * mapping as such. If the page has been used in |
| 373 | * another mapping, we will catch it; if this other |
| 374 | * mapping is already gone, the unmap path will have |
| 375 | * set PG_referenced or activated the page. |
| 376 | */ |
| 377 | if (likely(!VM_SequentialReadHint(vma))) |
| 378 | referenced++; |
| 379 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 380 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 381 | /* Pretend the page is referenced if the task has the |
| 382 | swap token and is in the middle of a page fault. */ |
Rik van Riel | f7b7fd8 | 2005-11-28 13:44:07 -0800 | [diff] [blame] | 383 | if (mm != current->mm && has_swap_token(mm) && |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 384 | rwsem_is_locked(&mm->mmap_sem)) |
| 385 | referenced++; |
| 386 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 387 | out_unmap: |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 388 | (*mapcount)--; |
| 389 | pte_unmap_unlock(pte, ptl); |
Huang Shijie | 273f047 | 2009-12-14 17:58:51 -0800 | [diff] [blame] | 390 | |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 391 | if (referenced) |
| 392 | *vm_flags |= vma->vm_flags; |
Huang Shijie | 273f047 | 2009-12-14 17:58:51 -0800 | [diff] [blame] | 393 | out: |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 394 | return referenced; |
| 395 | } |
| 396 | |
Balbir Singh | bed7161 | 2008-02-07 00:14:01 -0800 | [diff] [blame] | 397 | static int page_referenced_anon(struct page *page, |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 398 | struct mem_cgroup *mem_cont, |
| 399 | unsigned long *vm_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 400 | { |
| 401 | unsigned int mapcount; |
| 402 | struct anon_vma *anon_vma; |
| 403 | struct vm_area_struct *vma; |
| 404 | int referenced = 0; |
| 405 | |
| 406 | anon_vma = page_lock_anon_vma(page); |
| 407 | if (!anon_vma) |
| 408 | return referenced; |
| 409 | |
| 410 | mapcount = page_mapcount(page); |
| 411 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { |
Balbir Singh | bed7161 | 2008-02-07 00:14:01 -0800 | [diff] [blame] | 412 | /* |
| 413 | * If we are reclaiming on behalf of a cgroup, skip |
| 414 | * counting on behalf of references from different |
| 415 | * cgroups |
| 416 | */ |
Hugh Dickins | bd845e3 | 2008-03-04 14:29:01 -0800 | [diff] [blame] | 417 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
Balbir Singh | bed7161 | 2008-02-07 00:14:01 -0800 | [diff] [blame] | 418 | continue; |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 419 | referenced += page_referenced_one(page, vma, |
| 420 | &mapcount, vm_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 421 | if (!mapcount) |
| 422 | break; |
| 423 | } |
Oleg Nesterov | 34bbd70 | 2007-02-28 20:13:49 -0800 | [diff] [blame] | 424 | |
| 425 | page_unlock_anon_vma(anon_vma); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 426 | return referenced; |
| 427 | } |
| 428 | |
| 429 | /** |
| 430 | * page_referenced_file - referenced check for object-based rmap |
| 431 | * @page: the page we're checking references on. |
Randy Dunlap | 43d8eac | 2008-03-19 17:00:43 -0700 | [diff] [blame] | 432 | * @mem_cont: target memory controller |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 433 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 434 | * |
| 435 | * For an object-based mapped page, find all the places it is mapped and |
| 436 | * check/clear the referenced flag. This is done by following the page->mapping |
| 437 | * pointer, then walking the chain of vmas it holds. It returns the number |
| 438 | * of references it found. |
| 439 | * |
| 440 | * This function is only called from page_referenced for object-based pages. |
| 441 | */ |
Balbir Singh | bed7161 | 2008-02-07 00:14:01 -0800 | [diff] [blame] | 442 | static int page_referenced_file(struct page *page, |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 443 | struct mem_cgroup *mem_cont, |
| 444 | unsigned long *vm_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 445 | { |
| 446 | unsigned int mapcount; |
| 447 | struct address_space *mapping = page->mapping; |
| 448 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 449 | struct vm_area_struct *vma; |
| 450 | struct prio_tree_iter iter; |
| 451 | int referenced = 0; |
| 452 | |
| 453 | /* |
| 454 | * The caller's checks on page->mapping and !PageAnon have made |
| 455 | * sure that this is a file page: the check for page->mapping |
| 456 | * excludes the case just before it gets set on an anon page. |
| 457 | */ |
| 458 | BUG_ON(PageAnon(page)); |
| 459 | |
| 460 | /* |
| 461 | * The page lock not only makes sure that page->mapping cannot |
| 462 | * suddenly be NULLified by truncation, it makes sure that the |
| 463 | * structure at mapping cannot be freed and reused yet, |
| 464 | * so we can safely take mapping->i_mmap_lock. |
| 465 | */ |
| 466 | BUG_ON(!PageLocked(page)); |
| 467 | |
| 468 | spin_lock(&mapping->i_mmap_lock); |
| 469 | |
| 470 | /* |
| 471 | * i_mmap_lock does not stabilize mapcount at all, but mapcount |
| 472 | * is more likely to be accurate if we note it after spinning. |
| 473 | */ |
| 474 | mapcount = page_mapcount(page); |
| 475 | |
| 476 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
Balbir Singh | bed7161 | 2008-02-07 00:14:01 -0800 | [diff] [blame] | 477 | /* |
| 478 | * If we are reclaiming on behalf of a cgroup, skip |
| 479 | * counting on behalf of references from different |
| 480 | * cgroups |
| 481 | */ |
Hugh Dickins | bd845e3 | 2008-03-04 14:29:01 -0800 | [diff] [blame] | 482 | if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) |
Balbir Singh | bed7161 | 2008-02-07 00:14:01 -0800 | [diff] [blame] | 483 | continue; |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 484 | referenced += page_referenced_one(page, vma, |
| 485 | &mapcount, vm_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 486 | if (!mapcount) |
| 487 | break; |
| 488 | } |
| 489 | |
| 490 | spin_unlock(&mapping->i_mmap_lock); |
| 491 | return referenced; |
| 492 | } |
| 493 | |
| 494 | /** |
| 495 | * page_referenced - test if the page was referenced |
| 496 | * @page: the page to test |
| 497 | * @is_locked: caller holds lock on the page |
Randy Dunlap | 43d8eac | 2008-03-19 17:00:43 -0700 | [diff] [blame] | 498 | * @mem_cont: target memory controller |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 499 | * @vm_flags: collect encountered vma->vm_flags who actually referenced the page |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 500 | * |
| 501 | * Quick test_and_clear_referenced for all mappings to a page, |
| 502 | * returns the number of ptes which referenced the page. |
| 503 | */ |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 504 | int page_referenced(struct page *page, |
| 505 | int is_locked, |
| 506 | struct mem_cgroup *mem_cont, |
| 507 | unsigned long *vm_flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 508 | { |
| 509 | int referenced = 0; |
| 510 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 511 | if (TestClearPageReferenced(page)) |
| 512 | referenced++; |
| 513 | |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 514 | *vm_flags = 0; |
Hugh Dickins | 3ca7b3c | 2009-12-14 17:58:57 -0800 | [diff] [blame] | 515 | if (page_mapped(page) && page_rmapping(page)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 516 | if (PageAnon(page)) |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 517 | referenced += page_referenced_anon(page, mem_cont, |
| 518 | vm_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 519 | else if (is_locked) |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 520 | referenced += page_referenced_file(page, mem_cont, |
| 521 | vm_flags); |
Nick Piggin | 529ae9a | 2008-08-02 12:01:03 +0200 | [diff] [blame] | 522 | else if (!trylock_page(page)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 523 | referenced++; |
| 524 | else { |
| 525 | if (page->mapping) |
Wu Fengguang | 6fe6b7e | 2009-06-16 15:33:05 -0700 | [diff] [blame] | 526 | referenced += page_referenced_file(page, |
| 527 | mem_cont, vm_flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 528 | unlock_page(page); |
| 529 | } |
| 530 | } |
Christian Borntraeger | 5b7baf0 | 2008-03-25 18:47:12 +0100 | [diff] [blame] | 531 | |
| 532 | if (page_test_and_clear_young(page)) |
| 533 | referenced++; |
| 534 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 535 | return referenced; |
| 536 | } |
| 537 | |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 538 | static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) |
| 539 | { |
| 540 | struct mm_struct *mm = vma->vm_mm; |
| 541 | unsigned long address; |
Peter Zijlstra | c2fda5f | 2006-12-22 14:25:52 +0100 | [diff] [blame] | 542 | pte_t *pte; |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 543 | spinlock_t *ptl; |
| 544 | int ret = 0; |
| 545 | |
| 546 | address = vma_address(page, vma); |
| 547 | if (address == -EFAULT) |
| 548 | goto out; |
| 549 | |
Nick Piggin | 479db0b | 2008-08-20 14:09:18 -0700 | [diff] [blame] | 550 | pte = page_check_address(page, mm, address, &ptl, 1); |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 551 | if (!pte) |
| 552 | goto out; |
| 553 | |
Peter Zijlstra | c2fda5f | 2006-12-22 14:25:52 +0100 | [diff] [blame] | 554 | if (pte_dirty(*pte) || pte_write(*pte)) { |
| 555 | pte_t entry; |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 556 | |
Peter Zijlstra | c2fda5f | 2006-12-22 14:25:52 +0100 | [diff] [blame] | 557 | flush_cache_page(vma, address, pte_pfn(*pte)); |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 558 | entry = ptep_clear_flush_notify(vma, address, pte); |
Peter Zijlstra | c2fda5f | 2006-12-22 14:25:52 +0100 | [diff] [blame] | 559 | entry = pte_wrprotect(entry); |
| 560 | entry = pte_mkclean(entry); |
Al Viro | d6e88e6 | 2006-12-29 16:48:35 -0800 | [diff] [blame] | 561 | set_pte_at(mm, address, pte, entry); |
Peter Zijlstra | c2fda5f | 2006-12-22 14:25:52 +0100 | [diff] [blame] | 562 | ret = 1; |
| 563 | } |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 564 | |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 565 | pte_unmap_unlock(pte, ptl); |
| 566 | out: |
| 567 | return ret; |
| 568 | } |
| 569 | |
| 570 | static int page_mkclean_file(struct address_space *mapping, struct page *page) |
| 571 | { |
| 572 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 573 | struct vm_area_struct *vma; |
| 574 | struct prio_tree_iter iter; |
| 575 | int ret = 0; |
| 576 | |
| 577 | BUG_ON(PageAnon(page)); |
| 578 | |
| 579 | spin_lock(&mapping->i_mmap_lock); |
| 580 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
| 581 | if (vma->vm_flags & VM_SHARED) |
| 582 | ret += page_mkclean_one(page, vma); |
| 583 | } |
| 584 | spin_unlock(&mapping->i_mmap_lock); |
| 585 | return ret; |
| 586 | } |
| 587 | |
| 588 | int page_mkclean(struct page *page) |
| 589 | { |
| 590 | int ret = 0; |
| 591 | |
| 592 | BUG_ON(!PageLocked(page)); |
| 593 | |
| 594 | if (page_mapped(page)) { |
| 595 | struct address_space *mapping = page_mapping(page); |
Christian Borntraeger | ce7e9fa | 2007-11-20 11:13:36 +0100 | [diff] [blame] | 596 | if (mapping) { |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 597 | ret = page_mkclean_file(mapping, page); |
Christian Borntraeger | ce7e9fa | 2007-11-20 11:13:36 +0100 | [diff] [blame] | 598 | if (page_test_dirty(page)) { |
| 599 | page_clear_dirty(page); |
| 600 | ret = 1; |
| 601 | } |
Martin Schwidefsky | 6c21048 | 2007-04-27 16:01:57 +0200 | [diff] [blame] | 602 | } |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 603 | } |
| 604 | |
| 605 | return ret; |
| 606 | } |
Jaya Kumar | 60b59be | 2007-05-08 00:37:37 -0700 | [diff] [blame] | 607 | EXPORT_SYMBOL_GPL(page_mkclean); |
Peter Zijlstra | d08b385 | 2006-09-25 23:30:57 -0700 | [diff] [blame] | 608 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 609 | /** |
Randy Dunlap | 43d8eac | 2008-03-19 17:00:43 -0700 | [diff] [blame] | 610 | * __page_set_anon_rmap - setup new anonymous rmap |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 611 | * @page: the page to add the mapping to |
| 612 | * @vma: the vm area in which the mapping is added |
| 613 | * @address: the user virtual address mapped |
| 614 | */ |
| 615 | static void __page_set_anon_rmap(struct page *page, |
| 616 | struct vm_area_struct *vma, unsigned long address) |
| 617 | { |
| 618 | struct anon_vma *anon_vma = vma->anon_vma; |
| 619 | |
| 620 | BUG_ON(!anon_vma); |
| 621 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
| 622 | page->mapping = (struct address_space *) anon_vma; |
| 623 | |
| 624 | page->index = linear_page_index(vma, address); |
| 625 | |
Nick Piggin | a74609f | 2006-01-06 00:11:20 -0800 | [diff] [blame] | 626 | /* |
| 627 | * nr_mapped state can be updated without turning off |
| 628 | * interrupts because it is not modified via interrupt. |
| 629 | */ |
Christoph Lameter | f3dbd34 | 2006-06-30 01:55:36 -0700 | [diff] [blame] | 630 | __inc_zone_page_state(page, NR_ANON_PAGES); |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 631 | } |
| 632 | |
| 633 | /** |
Randy Dunlap | 43d8eac | 2008-03-19 17:00:43 -0700 | [diff] [blame] | 634 | * __page_check_anon_rmap - sanity check anonymous rmap addition |
Nick Piggin | c97a9e1 | 2007-05-16 22:11:21 -0700 | [diff] [blame] | 635 | * @page: the page to add the mapping to |
| 636 | * @vma: the vm area in which the mapping is added |
| 637 | * @address: the user virtual address mapped |
| 638 | */ |
| 639 | static void __page_check_anon_rmap(struct page *page, |
| 640 | struct vm_area_struct *vma, unsigned long address) |
| 641 | { |
| 642 | #ifdef CONFIG_DEBUG_VM |
| 643 | /* |
| 644 | * The page's anon-rmap details (mapping and index) are guaranteed to |
| 645 | * be set up correctly at this point. |
| 646 | * |
| 647 | * We have exclusion against page_add_anon_rmap because the caller |
| 648 | * always holds the page locked, except if called from page_dup_rmap, |
| 649 | * in which case the page is already known to be setup. |
| 650 | * |
| 651 | * We have exclusion against page_add_new_anon_rmap because those pages |
| 652 | * are initially only visible via the pagetables, and the pte is locked |
| 653 | * over the call to page_add_new_anon_rmap. |
| 654 | */ |
| 655 | struct anon_vma *anon_vma = vma->anon_vma; |
| 656 | anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |
| 657 | BUG_ON(page->mapping != (struct address_space *)anon_vma); |
| 658 | BUG_ON(page->index != linear_page_index(vma, address)); |
| 659 | #endif |
| 660 | } |
| 661 | |
| 662 | /** |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 663 | * page_add_anon_rmap - add pte mapping to an anonymous page |
| 664 | * @page: the page to add the mapping to |
| 665 | * @vma: the vm area in which the mapping is added |
| 666 | * @address: the user virtual address mapped |
| 667 | * |
Nick Piggin | c97a9e1 | 2007-05-16 22:11:21 -0700 | [diff] [blame] | 668 | * The caller needs to hold the pte lock and the page must be locked. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 669 | */ |
| 670 | void page_add_anon_rmap(struct page *page, |
| 671 | struct vm_area_struct *vma, unsigned long address) |
| 672 | { |
Nick Piggin | c97a9e1 | 2007-05-16 22:11:21 -0700 | [diff] [blame] | 673 | VM_BUG_ON(!PageLocked(page)); |
| 674 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 675 | if (atomic_inc_and_test(&page->_mapcount)) |
| 676 | __page_set_anon_rmap(page, vma, address); |
KAMEZAWA Hiroyuki | 69029cd | 2008-07-25 01:47:14 -0700 | [diff] [blame] | 677 | else |
Nick Piggin | c97a9e1 | 2007-05-16 22:11:21 -0700 | [diff] [blame] | 678 | __page_check_anon_rmap(page, vma, address); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 679 | } |
| 680 | |
Randy Dunlap | 43d8eac | 2008-03-19 17:00:43 -0700 | [diff] [blame] | 681 | /** |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 682 | * page_add_new_anon_rmap - add pte mapping to a new anonymous page |
| 683 | * @page: the page to add the mapping to |
| 684 | * @vma: the vm area in which the mapping is added |
| 685 | * @address: the user virtual address mapped |
| 686 | * |
| 687 | * Same as page_add_anon_rmap but must only be called on *new* pages. |
| 688 | * This means the inc-and-test can be bypassed. |
Nick Piggin | c97a9e1 | 2007-05-16 22:11:21 -0700 | [diff] [blame] | 689 | * Page does not have to be locked. |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 690 | */ |
| 691 | void page_add_new_anon_rmap(struct page *page, |
| 692 | struct vm_area_struct *vma, unsigned long address) |
| 693 | { |
Hugh Dickins | b5934c5 | 2009-01-06 14:39:25 -0800 | [diff] [blame] | 694 | VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); |
Hugh Dickins | cbf84b7 | 2009-01-06 14:39:27 -0800 | [diff] [blame] | 695 | SetPageSwapBacked(page); |
| 696 | atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 697 | __page_set_anon_rmap(page, vma, address); |
Hugh Dickins | b5934c5 | 2009-01-06 14:39:25 -0800 | [diff] [blame] | 698 | if (page_evictable(page, vma)) |
Hugh Dickins | cbf84b7 | 2009-01-06 14:39:27 -0800 | [diff] [blame] | 699 | lru_cache_add_lru(page, LRU_ACTIVE_ANON); |
Hugh Dickins | b5934c5 | 2009-01-06 14:39:25 -0800 | [diff] [blame] | 700 | else |
| 701 | add_page_to_unevictable_list(page); |
Nick Piggin | 9617d95 | 2006-01-06 00:11:12 -0800 | [diff] [blame] | 702 | } |
| 703 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 704 | /** |
| 705 | * page_add_file_rmap - add pte mapping to a file page |
| 706 | * @page: the page to add the mapping to |
| 707 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 708 | * The caller needs to hold the pte lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 709 | */ |
| 710 | void page_add_file_rmap(struct page *page) |
| 711 | { |
Balbir Singh | d69b042 | 2009-06-17 16:26:34 -0700 | [diff] [blame] | 712 | if (atomic_inc_and_test(&page->_mapcount)) { |
Christoph Lameter | 65ba55f | 2006-06-30 01:55:34 -0700 | [diff] [blame] | 713 | __inc_zone_page_state(page, NR_FILE_MAPPED); |
Balbir Singh | d69b042 | 2009-06-17 16:26:34 -0700 | [diff] [blame] | 714 | mem_cgroup_update_mapped_file_stat(page, 1); |
| 715 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 716 | } |
| 717 | |
| 718 | /** |
| 719 | * page_remove_rmap - take down pte mapping from a page |
| 720 | * @page: page to remove mapping from |
| 721 | * |
Hugh Dickins | b8072f0 | 2005-10-29 18:16:41 -0700 | [diff] [blame] | 722 | * The caller needs to hold the pte lock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 723 | */ |
Hugh Dickins | edc315f | 2009-01-06 14:40:11 -0800 | [diff] [blame] | 724 | void page_remove_rmap(struct page *page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 725 | { |
KOSAKI Motohiro | b904dcf | 2009-09-21 17:01:28 -0700 | [diff] [blame] | 726 | /* page still mapped by someone else? */ |
| 727 | if (!atomic_add_negative(-1, &page->_mapcount)) |
| 728 | return; |
| 729 | |
| 730 | /* |
| 731 | * Now that the last pte has gone, s390 must transfer dirty |
| 732 | * flag from storage key to struct page. We can usually skip |
| 733 | * this if the page is anon, so about to be freed; but perhaps |
| 734 | * not if it's in swapcache - there might be another pte slot |
| 735 | * containing the swap entry, but page not yet written to swap. |
| 736 | */ |
| 737 | if ((!PageAnon(page) || PageSwapCache(page)) && page_test_dirty(page)) { |
| 738 | page_clear_dirty(page); |
| 739 | set_page_dirty(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 740 | } |
KOSAKI Motohiro | b904dcf | 2009-09-21 17:01:28 -0700 | [diff] [blame] | 741 | if (PageAnon(page)) { |
| 742 | mem_cgroup_uncharge_page(page); |
| 743 | __dec_zone_page_state(page, NR_ANON_PAGES); |
| 744 | } else { |
| 745 | __dec_zone_page_state(page, NR_FILE_MAPPED); |
| 746 | } |
| 747 | mem_cgroup_update_mapped_file_stat(page, -1); |
| 748 | /* |
| 749 | * It would be tidy to reset the PageAnon mapping here, |
| 750 | * but that might overwrite a racing page_add_anon_rmap |
| 751 | * which increments mapcount after us but sets mapping |
| 752 | * before us: so leave the reset to free_hot_cold_page, |
| 753 | * and remember that it's only reliable while mapped. |
| 754 | * Leaving it set also helps swapoff to reinstate ptes |
| 755 | * faster for those pages still in swapcache. |
| 756 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 757 | } |
| 758 | |
| 759 | /* |
| 760 | * Subfunctions of try_to_unmap: try_to_unmap_one called |
| 761 | * repeatedly from either try_to_unmap_anon or try_to_unmap_file. |
| 762 | */ |
Christoph Lameter | a48d07a | 2006-02-01 03:05:38 -0800 | [diff] [blame] | 763 | static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 764 | enum ttu_flags flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 765 | { |
| 766 | struct mm_struct *mm = vma->vm_mm; |
| 767 | unsigned long address; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 768 | pte_t *pte; |
| 769 | pte_t pteval; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 770 | spinlock_t *ptl; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 771 | int ret = SWAP_AGAIN; |
| 772 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 773 | address = vma_address(page, vma); |
| 774 | if (address == -EFAULT) |
| 775 | goto out; |
| 776 | |
Nick Piggin | 479db0b | 2008-08-20 14:09:18 -0700 | [diff] [blame] | 777 | pte = page_check_address(page, mm, address, &ptl, 0); |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 778 | if (!pte) |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 779 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 780 | |
| 781 | /* |
| 782 | * If the page is mlock()d, we cannot swap it out. |
| 783 | * If it's recently referenced (perhaps page_referenced |
| 784 | * skipped over this mm) then we should reactivate it. |
| 785 | */ |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 786 | if (!(flags & TTU_IGNORE_MLOCK)) { |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 787 | if (vma->vm_flags & VM_LOCKED) { |
| 788 | ret = SWAP_MLOCK; |
| 789 | goto out_unmap; |
| 790 | } |
Hugh Dickins | af8e335 | 2009-12-14 17:58:59 -0800 | [diff] [blame^] | 791 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 792 | goto out_unmap; |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 793 | } |
| 794 | if (!(flags & TTU_IGNORE_ACCESS)) { |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 795 | if (ptep_clear_flush_young_notify(vma, address, pte)) { |
| 796 | ret = SWAP_FAIL; |
| 797 | goto out_unmap; |
| 798 | } |
| 799 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 800 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 801 | /* Nuke the page table entry. */ |
| 802 | flush_cache_page(vma, address, page_to_pfn(page)); |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 803 | pteval = ptep_clear_flush_notify(vma, address, pte); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 804 | |
| 805 | /* Move the dirty bit to the physical page now the pte is gone. */ |
| 806 | if (pte_dirty(pteval)) |
| 807 | set_page_dirty(page); |
| 808 | |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 809 | /* Update high watermark before we lower rss */ |
| 810 | update_hiwater_rss(mm); |
| 811 | |
Andi Kleen | 888b9f7 | 2009-09-16 11:50:11 +0200 | [diff] [blame] | 812 | if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { |
| 813 | if (PageAnon(page)) |
| 814 | dec_mm_counter(mm, anon_rss); |
| 815 | else |
| 816 | dec_mm_counter(mm, file_rss); |
| 817 | set_pte_at(mm, address, pte, |
| 818 | swp_entry_to_pte(make_hwpoison_entry(page))); |
| 819 | } else if (PageAnon(page)) { |
Hugh Dickins | 4c21e2f | 2005-10-29 18:16:40 -0700 | [diff] [blame] | 820 | swp_entry_t entry = { .val = page_private(page) }; |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 821 | |
| 822 | if (PageSwapCache(page)) { |
| 823 | /* |
| 824 | * Store the swap location in the pte. |
| 825 | * See handle_pte_fault() ... |
| 826 | */ |
Hugh Dickins | 570a335 | 2009-12-14 17:58:46 -0800 | [diff] [blame] | 827 | if (swap_duplicate(entry) < 0) { |
| 828 | set_pte_at(mm, address, pte, pteval); |
| 829 | ret = SWAP_FAIL; |
| 830 | goto out_unmap; |
| 831 | } |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 832 | if (list_empty(&mm->mmlist)) { |
| 833 | spin_lock(&mmlist_lock); |
| 834 | if (list_empty(&mm->mmlist)) |
| 835 | list_add(&mm->mmlist, &init_mm.mmlist); |
| 836 | spin_unlock(&mmlist_lock); |
| 837 | } |
Christoph Lameter | 442c913 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 838 | dec_mm_counter(mm, anon_rss); |
KOSAKI Motohiro | 64cdd54 | 2009-01-06 14:39:16 -0800 | [diff] [blame] | 839 | } else if (PAGE_MIGRATION) { |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 840 | /* |
| 841 | * Store the pfn of the page in a special migration |
| 842 | * pte. do_swap_page() will wait until the migration |
| 843 | * pte is removed and then restart fault handling. |
| 844 | */ |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 845 | BUG_ON(TTU_ACTION(flags) != TTU_MIGRATION); |
Christoph Lameter | 0697212 | 2006-06-23 02:03:35 -0700 | [diff] [blame] | 846 | entry = make_migration_entry(page, pte_write(pteval)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 847 | } |
| 848 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
| 849 | BUG_ON(pte_file(*pte)); |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 850 | } else if (PAGE_MIGRATION && (TTU_ACTION(flags) == TTU_MIGRATION)) { |
Christoph Lameter | 04e62a2 | 2006-06-23 02:03:38 -0700 | [diff] [blame] | 851 | /* Establish migration entry for a file page */ |
| 852 | swp_entry_t entry; |
| 853 | entry = make_migration_entry(page, pte_write(pteval)); |
| 854 | set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); |
| 855 | } else |
Hugh Dickins | 4294621 | 2005-10-29 18:16:05 -0700 | [diff] [blame] | 856 | dec_mm_counter(mm, file_rss); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 857 | |
Hugh Dickins | edc315f | 2009-01-06 14:40:11 -0800 | [diff] [blame] | 858 | page_remove_rmap(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 859 | page_cache_release(page); |
| 860 | |
| 861 | out_unmap: |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 862 | pte_unmap_unlock(pte, ptl); |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 863 | |
Hugh Dickins | af8e335 | 2009-12-14 17:58:59 -0800 | [diff] [blame^] | 864 | if (ret == SWAP_MLOCK) { |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 865 | ret = SWAP_AGAIN; |
| 866 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
| 867 | if (vma->vm_flags & VM_LOCKED) { |
| 868 | mlock_vma_page(page); |
| 869 | ret = SWAP_MLOCK; |
| 870 | } |
| 871 | up_read(&vma->vm_mm->mmap_sem); |
| 872 | } |
| 873 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 874 | out: |
| 875 | return ret; |
| 876 | } |
| 877 | |
| 878 | /* |
| 879 | * objrmap doesn't work for nonlinear VMAs because the assumption that |
| 880 | * offset-into-file correlates with offset-into-virtual-addresses does not hold. |
| 881 | * Consequently, given a particular page and its ->index, we cannot locate the |
| 882 | * ptes which are mapping that page without an exhaustive linear search. |
| 883 | * |
| 884 | * So what this code does is a mini "virtual scan" of each nonlinear VMA which |
| 885 | * maps the file to which the target page belongs. The ->vm_private_data field |
| 886 | * holds the current cursor into that scan. Successive searches will circulate |
| 887 | * around the vma's virtual address space. |
| 888 | * |
| 889 | * So as more replacement pressure is applied to the pages in a nonlinear VMA, |
| 890 | * more scanning pressure is placed against them as well. Eventually pages |
| 891 | * will become fully unmapped and are eligible for eviction. |
| 892 | * |
| 893 | * For very sparsely populated VMAs this is a little inefficient - chances are |
| 894 | * there there won't be many ptes located within the scan cluster. In this case |
| 895 | * maybe we could scan further - to the end of the pte page, perhaps. |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 896 | * |
| 897 | * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can |
| 898 | * acquire it without blocking. If vma locked, mlock the pages in the cluster, |
| 899 | * rather than unmapping them. If we encounter the "check_page" that vmscan is |
| 900 | * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 901 | */ |
| 902 | #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) |
| 903 | #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) |
| 904 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 905 | static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, |
| 906 | struct vm_area_struct *vma, struct page *check_page) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 907 | { |
| 908 | struct mm_struct *mm = vma->vm_mm; |
| 909 | pgd_t *pgd; |
| 910 | pud_t *pud; |
| 911 | pmd_t *pmd; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 912 | pte_t *pte; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 913 | pte_t pteval; |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 914 | spinlock_t *ptl; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 915 | struct page *page; |
| 916 | unsigned long address; |
| 917 | unsigned long end; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 918 | int ret = SWAP_AGAIN; |
| 919 | int locked_vma = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 920 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 921 | address = (vma->vm_start + cursor) & CLUSTER_MASK; |
| 922 | end = address + CLUSTER_SIZE; |
| 923 | if (address < vma->vm_start) |
| 924 | address = vma->vm_start; |
| 925 | if (end > vma->vm_end) |
| 926 | end = vma->vm_end; |
| 927 | |
| 928 | pgd = pgd_offset(mm, address); |
| 929 | if (!pgd_present(*pgd)) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 930 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 931 | |
| 932 | pud = pud_offset(pgd, address); |
| 933 | if (!pud_present(*pud)) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 934 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 935 | |
| 936 | pmd = pmd_offset(pud, address); |
| 937 | if (!pmd_present(*pmd)) |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 938 | return ret; |
| 939 | |
| 940 | /* |
Hugh Dickins | af8e335 | 2009-12-14 17:58:59 -0800 | [diff] [blame^] | 941 | * If we can acquire the mmap_sem for read, and vma is VM_LOCKED, |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 942 | * keep the sem while scanning the cluster for mlocking pages. |
| 943 | */ |
Hugh Dickins | af8e335 | 2009-12-14 17:58:59 -0800 | [diff] [blame^] | 944 | if (down_read_trylock(&vma->vm_mm->mmap_sem)) { |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 945 | locked_vma = (vma->vm_flags & VM_LOCKED); |
| 946 | if (!locked_vma) |
| 947 | up_read(&vma->vm_mm->mmap_sem); /* don't need it */ |
| 948 | } |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 949 | |
| 950 | pte = pte_offset_map_lock(mm, pmd, address, &ptl); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 951 | |
Hugh Dickins | 365e9c87 | 2005-10-29 18:16:18 -0700 | [diff] [blame] | 952 | /* Update high watermark before we lower rss */ |
| 953 | update_hiwater_rss(mm); |
| 954 | |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 955 | for (; address < end; pte++, address += PAGE_SIZE) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 956 | if (!pte_present(*pte)) |
| 957 | continue; |
Linus Torvalds | 6aab341 | 2005-11-28 14:34:23 -0800 | [diff] [blame] | 958 | page = vm_normal_page(vma, address, *pte); |
| 959 | BUG_ON(!page || PageAnon(page)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 960 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 961 | if (locked_vma) { |
| 962 | mlock_vma_page(page); /* no-op if already mlocked */ |
| 963 | if (page == check_page) |
| 964 | ret = SWAP_MLOCK; |
| 965 | continue; /* don't unmap */ |
| 966 | } |
| 967 | |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 968 | if (ptep_clear_flush_young_notify(vma, address, pte)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 969 | continue; |
| 970 | |
| 971 | /* Nuke the page table entry. */ |
Ben Collins | eca3513 | 2005-11-29 11:45:26 -0800 | [diff] [blame] | 972 | flush_cache_page(vma, address, pte_pfn(*pte)); |
Andrea Arcangeli | cddb8a5 | 2008-07-28 15:46:29 -0700 | [diff] [blame] | 973 | pteval = ptep_clear_flush_notify(vma, address, pte); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 974 | |
| 975 | /* If nonlinear, store the file page offset in the pte. */ |
| 976 | if (page->index != linear_page_index(vma, address)) |
| 977 | set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); |
| 978 | |
| 979 | /* Move the dirty bit to the physical page now the pte is gone. */ |
| 980 | if (pte_dirty(pteval)) |
| 981 | set_page_dirty(page); |
| 982 | |
Hugh Dickins | edc315f | 2009-01-06 14:40:11 -0800 | [diff] [blame] | 983 | page_remove_rmap(page); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 984 | page_cache_release(page); |
Hugh Dickins | 4294621 | 2005-10-29 18:16:05 -0700 | [diff] [blame] | 985 | dec_mm_counter(mm, file_rss); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 986 | (*mapcount)--; |
| 987 | } |
Hugh Dickins | c071880 | 2005-10-29 18:16:31 -0700 | [diff] [blame] | 988 | pte_unmap_unlock(pte - 1, ptl); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 989 | if (locked_vma) |
| 990 | up_read(&vma->vm_mm->mmap_sem); |
| 991 | return ret; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 992 | } |
| 993 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 994 | /** |
| 995 | * try_to_unmap_anon - unmap or unlock anonymous page using the object-based |
| 996 | * rmap method |
| 997 | * @page: the page to unmap/unlock |
Huang Shijie | 8051be5 | 2009-12-14 17:58:50 -0800 | [diff] [blame] | 998 | * @flags: action and flags |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 999 | * |
| 1000 | * Find all the mappings of a page using the mapping pointer and the vma chains |
| 1001 | * contained in the anon_vma struct it points to. |
| 1002 | * |
| 1003 | * This function is only called from try_to_unmap/try_to_munlock for |
| 1004 | * anonymous pages. |
| 1005 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma |
| 1006 | * where the page was found will be held for write. So, we won't recheck |
| 1007 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be |
| 1008 | * 'LOCKED. |
| 1009 | */ |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1010 | static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1011 | { |
| 1012 | struct anon_vma *anon_vma; |
| 1013 | struct vm_area_struct *vma; |
| 1014 | int ret = SWAP_AGAIN; |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1015 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1016 | anon_vma = page_lock_anon_vma(page); |
| 1017 | if (!anon_vma) |
| 1018 | return ret; |
| 1019 | |
| 1020 | list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 1021 | ret = try_to_unmap_one(page, vma, flags); |
| 1022 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
| 1023 | break; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1024 | } |
Oleg Nesterov | 34bbd70 | 2007-02-28 20:13:49 -0800 | [diff] [blame] | 1025 | |
| 1026 | page_unlock_anon_vma(anon_vma); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1027 | return ret; |
| 1028 | } |
| 1029 | |
| 1030 | /** |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1031 | * try_to_unmap_file - unmap/unlock file page using the object-based rmap method |
| 1032 | * @page: the page to unmap/unlock |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1033 | * @flags: action and flags |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1034 | * |
| 1035 | * Find all the mappings of a page using the mapping pointer and the vma chains |
| 1036 | * contained in the address_space struct it points to. |
| 1037 | * |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1038 | * This function is only called from try_to_unmap/try_to_munlock for |
| 1039 | * object-based pages. |
| 1040 | * When called from try_to_munlock(), the mmap_sem of the mm containing the vma |
| 1041 | * where the page was found will be held for write. So, we won't recheck |
| 1042 | * vm_flags for that VMA. That should be OK, because that vma shouldn't be |
| 1043 | * 'LOCKED. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1044 | */ |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1045 | static int try_to_unmap_file(struct page *page, enum ttu_flags flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1046 | { |
| 1047 | struct address_space *mapping = page->mapping; |
| 1048 | pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); |
| 1049 | struct vm_area_struct *vma; |
| 1050 | struct prio_tree_iter iter; |
| 1051 | int ret = SWAP_AGAIN; |
| 1052 | unsigned long cursor; |
| 1053 | unsigned long max_nl_cursor = 0; |
| 1054 | unsigned long max_nl_size = 0; |
| 1055 | unsigned int mapcount; |
| 1056 | |
| 1057 | spin_lock(&mapping->i_mmap_lock); |
| 1058 | vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 1059 | ret = try_to_unmap_one(page, vma, flags); |
| 1060 | if (ret != SWAP_AGAIN || !page_mapped(page)) |
| 1061 | goto out; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1062 | } |
| 1063 | |
| 1064 | if (list_empty(&mapping->i_mmap_nonlinear)) |
| 1065 | goto out; |
| 1066 | |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 1067 | /* |
| 1068 | * We don't bother to try to find the munlocked page in nonlinears. |
| 1069 | * It's costly. Instead, later, page reclaim logic may call |
| 1070 | * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily. |
| 1071 | */ |
| 1072 | if (TTU_ACTION(flags) == TTU_MUNLOCK) |
| 1073 | goto out; |
| 1074 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1075 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
| 1076 | shared.vm_set.list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1077 | cursor = (unsigned long) vma->vm_private_data; |
| 1078 | if (cursor > max_nl_cursor) |
| 1079 | max_nl_cursor = cursor; |
| 1080 | cursor = vma->vm_end - vma->vm_start; |
| 1081 | if (cursor > max_nl_size) |
| 1082 | max_nl_size = cursor; |
| 1083 | } |
| 1084 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1085 | if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1086 | ret = SWAP_FAIL; |
| 1087 | goto out; |
| 1088 | } |
| 1089 | |
| 1090 | /* |
| 1091 | * We don't try to search for this page in the nonlinear vmas, |
| 1092 | * and page_referenced wouldn't have found it anyway. Instead |
| 1093 | * just walk the nonlinear vmas trying to age and unmap some. |
| 1094 | * The mapcount of the page we came in with is irrelevant, |
| 1095 | * but even so use it as a guide to how hard we should try? |
| 1096 | */ |
| 1097 | mapcount = page_mapcount(page); |
| 1098 | if (!mapcount) |
| 1099 | goto out; |
| 1100 | cond_resched_lock(&mapping->i_mmap_lock); |
| 1101 | |
| 1102 | max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; |
| 1103 | if (max_nl_cursor == 0) |
| 1104 | max_nl_cursor = CLUSTER_SIZE; |
| 1105 | |
| 1106 | do { |
| 1107 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, |
| 1108 | shared.vm_set.list) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1109 | cursor = (unsigned long) vma->vm_private_data; |
Hugh Dickins | 839b968 | 2005-09-03 15:54:43 -0700 | [diff] [blame] | 1110 | while ( cursor < max_nl_cursor && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1111 | cursor < vma->vm_end - vma->vm_start) { |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 1112 | if (try_to_unmap_cluster(cursor, &mapcount, |
| 1113 | vma, page) == SWAP_MLOCK) |
| 1114 | ret = SWAP_MLOCK; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1115 | cursor += CLUSTER_SIZE; |
| 1116 | vma->vm_private_data = (void *) cursor; |
| 1117 | if ((int)mapcount <= 0) |
| 1118 | goto out; |
| 1119 | } |
| 1120 | vma->vm_private_data = (void *) max_nl_cursor; |
| 1121 | } |
| 1122 | cond_resched_lock(&mapping->i_mmap_lock); |
| 1123 | max_nl_cursor += CLUSTER_SIZE; |
| 1124 | } while (max_nl_cursor <= max_nl_size); |
| 1125 | |
| 1126 | /* |
| 1127 | * Don't loop forever (perhaps all the remaining pages are |
| 1128 | * in locked vmas). Reset cursor on all unreserved nonlinear |
| 1129 | * vmas, now forgetting on which ones it had fallen behind. |
| 1130 | */ |
Hugh Dickins | 101d2be | 2005-11-21 21:32:16 -0800 | [diff] [blame] | 1131 | list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) |
| 1132 | vma->vm_private_data = NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1133 | out: |
| 1134 | spin_unlock(&mapping->i_mmap_lock); |
| 1135 | return ret; |
| 1136 | } |
| 1137 | |
| 1138 | /** |
| 1139 | * try_to_unmap - try to remove all page table mappings to a page |
| 1140 | * @page: the page to get unmapped |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1141 | * @flags: action and flags |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1142 | * |
| 1143 | * Tries to remove all the page table entries which are mapping this |
| 1144 | * page, used in the pageout path. Caller must hold the page lock. |
| 1145 | * Return values are: |
| 1146 | * |
| 1147 | * SWAP_SUCCESS - we succeeded in removing all mappings |
| 1148 | * SWAP_AGAIN - we missed a mapping, try again later |
| 1149 | * SWAP_FAIL - the page is unswappable |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1150 | * SWAP_MLOCK - page is mlocked. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1151 | */ |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1152 | int try_to_unmap(struct page *page, enum ttu_flags flags) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1153 | { |
| 1154 | int ret; |
| 1155 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1156 | BUG_ON(!PageLocked(page)); |
| 1157 | |
| 1158 | if (PageAnon(page)) |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1159 | ret = try_to_unmap_anon(page, flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1160 | else |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1161 | ret = try_to_unmap_file(page, flags); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1162 | if (ret != SWAP_MLOCK && !page_mapped(page)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1163 | ret = SWAP_SUCCESS; |
| 1164 | return ret; |
| 1165 | } |
Nikita Danilov | 81b4082 | 2005-05-01 08:58:36 -0700 | [diff] [blame] | 1166 | |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1167 | /** |
| 1168 | * try_to_munlock - try to munlock a page |
| 1169 | * @page: the page to be munlocked |
| 1170 | * |
| 1171 | * Called from munlock code. Checks all of the VMAs mapping the page |
| 1172 | * to make sure nobody else has this page mlocked. The page will be |
| 1173 | * returned with PG_mlocked cleared if no other vmas have it mlocked. |
| 1174 | * |
| 1175 | * Return values are: |
| 1176 | * |
Hugh Dickins | 53f79ac | 2009-12-14 17:58:58 -0800 | [diff] [blame] | 1177 | * SWAP_AGAIN - no vma is holding page mlocked, or, |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1178 | * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem |
| 1179 | * SWAP_MLOCK - page is now mlocked. |
| 1180 | */ |
| 1181 | int try_to_munlock(struct page *page) |
| 1182 | { |
| 1183 | VM_BUG_ON(!PageLocked(page) || PageLRU(page)); |
| 1184 | |
| 1185 | if (PageAnon(page)) |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1186 | return try_to_unmap_anon(page, TTU_MUNLOCK); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1187 | else |
Andi Kleen | 14fa31b | 2009-09-16 11:50:10 +0200 | [diff] [blame] | 1188 | return try_to_unmap_file(page, TTU_MUNLOCK); |
Nick Piggin | b291f00 | 2008-10-18 20:26:44 -0700 | [diff] [blame] | 1189 | } |
KOSAKI Motohiro | 6837765 | 2009-06-16 15:32:51 -0700 | [diff] [blame] | 1190 | |