11da177e4SLinus Torvalds /* 21da177e4SLinus Torvalds * mm/rmap.c - physical to virtual reverse mappings 31da177e4SLinus Torvalds * 41da177e4SLinus Torvalds * Copyright 2001, Rik van Riel <riel@conectiva.com.br> 51da177e4SLinus Torvalds * Released under the General Public License (GPL). 61da177e4SLinus Torvalds * 71da177e4SLinus Torvalds * Simple, low overhead reverse mapping scheme. 81da177e4SLinus Torvalds * Please try to keep this thing as modular as possible. 91da177e4SLinus Torvalds * 101da177e4SLinus Torvalds * Provides methods for unmapping each kind of mapped page: 111da177e4SLinus Torvalds * the anon methods track anonymous pages, and 121da177e4SLinus Torvalds * the file methods track pages belonging to an inode. 131da177e4SLinus Torvalds * 141da177e4SLinus Torvalds * Original design by Rik van Riel <riel@conectiva.com.br> 2001 151da177e4SLinus Torvalds * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 161da177e4SLinus Torvalds * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 171da177e4SLinus Torvalds * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004 181da177e4SLinus Torvalds */ 191da177e4SLinus Torvalds 201da177e4SLinus Torvalds /* 211da177e4SLinus Torvalds * Lock ordering in mm: 221da177e4SLinus Torvalds * 231da177e4SLinus Torvalds * inode->i_sem (while writing or truncating, not reading or faulting) 241da177e4SLinus Torvalds * inode->i_alloc_sem 251da177e4SLinus Torvalds * 261da177e4SLinus Torvalds * When a page fault occurs in writing from user to file, down_read 271da177e4SLinus Torvalds * of mmap_sem nests within i_sem; in sys_msync, i_sem nests within 281da177e4SLinus Torvalds * down_read of mmap_sem; i_sem and down_write of mmap_sem are never 291da177e4SLinus Torvalds * taken together; in truncation, i_sem is taken outermost. 301da177e4SLinus Torvalds * 311da177e4SLinus Torvalds * mm->mmap_sem 321da177e4SLinus Torvalds * page->flags PG_locked (lock_page) 331da177e4SLinus Torvalds * mapping->i_mmap_lock 341da177e4SLinus Torvalds * anon_vma->lock 35*b8072f09SHugh Dickins * mm->page_table_lock or pte_lock 361da177e4SLinus Torvalds * zone->lru_lock (in mark_page_accessed) 375d337b91SHugh Dickins * swap_lock (in swap_duplicate, swap_info_get) 381da177e4SLinus Torvalds * mmlist_lock (in mmput, drain_mmlist and others) 391da177e4SLinus Torvalds * mapping->private_lock (in __set_page_dirty_buffers) 401da177e4SLinus Torvalds * inode_lock (in set_page_dirty's __mark_inode_dirty) 411da177e4SLinus Torvalds * sb_lock (within inode_lock in fs/fs-writeback.c) 421da177e4SLinus Torvalds * mapping->tree_lock (widely used, in set_page_dirty, 431da177e4SLinus Torvalds * in arch-dependent flush_dcache_mmap_lock, 441da177e4SLinus Torvalds * within inode_lock in __sync_single_inode) 451da177e4SLinus Torvalds */ 461da177e4SLinus Torvalds 471da177e4SLinus Torvalds #include <linux/mm.h> 481da177e4SLinus Torvalds #include <linux/pagemap.h> 491da177e4SLinus Torvalds #include <linux/swap.h> 501da177e4SLinus Torvalds #include <linux/swapops.h> 511da177e4SLinus Torvalds #include <linux/slab.h> 521da177e4SLinus Torvalds #include <linux/init.h> 531da177e4SLinus Torvalds #include <linux/rmap.h> 541da177e4SLinus Torvalds #include <linux/rcupdate.h> 551da177e4SLinus Torvalds 561da177e4SLinus Torvalds #include <asm/tlbflush.h> 571da177e4SLinus Torvalds 581da177e4SLinus Torvalds //#define RMAP_DEBUG /* can be enabled only for debugging */ 591da177e4SLinus Torvalds 601da177e4SLinus Torvalds kmem_cache_t *anon_vma_cachep; 611da177e4SLinus Torvalds 621da177e4SLinus Torvalds static inline void validate_anon_vma(struct vm_area_struct *find_vma) 631da177e4SLinus Torvalds { 641da177e4SLinus Torvalds #ifdef RMAP_DEBUG 651da177e4SLinus Torvalds struct anon_vma *anon_vma = find_vma->anon_vma; 661da177e4SLinus Torvalds struct vm_area_struct *vma; 671da177e4SLinus Torvalds unsigned int mapcount = 0; 681da177e4SLinus Torvalds int found = 0; 691da177e4SLinus Torvalds 701da177e4SLinus Torvalds list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { 711da177e4SLinus Torvalds mapcount++; 721da177e4SLinus Torvalds BUG_ON(mapcount > 100000); 731da177e4SLinus Torvalds if (vma == find_vma) 741da177e4SLinus Torvalds found = 1; 751da177e4SLinus Torvalds } 761da177e4SLinus Torvalds BUG_ON(!found); 771da177e4SLinus Torvalds #endif 781da177e4SLinus Torvalds } 791da177e4SLinus Torvalds 801da177e4SLinus Torvalds /* This must be called under the mmap_sem. */ 811da177e4SLinus Torvalds int anon_vma_prepare(struct vm_area_struct *vma) 821da177e4SLinus Torvalds { 831da177e4SLinus Torvalds struct anon_vma *anon_vma = vma->anon_vma; 841da177e4SLinus Torvalds 851da177e4SLinus Torvalds might_sleep(); 861da177e4SLinus Torvalds if (unlikely(!anon_vma)) { 871da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 881da177e4SLinus Torvalds struct anon_vma *allocated, *locked; 891da177e4SLinus Torvalds 901da177e4SLinus Torvalds anon_vma = find_mergeable_anon_vma(vma); 911da177e4SLinus Torvalds if (anon_vma) { 921da177e4SLinus Torvalds allocated = NULL; 931da177e4SLinus Torvalds locked = anon_vma; 941da177e4SLinus Torvalds spin_lock(&locked->lock); 951da177e4SLinus Torvalds } else { 961da177e4SLinus Torvalds anon_vma = anon_vma_alloc(); 971da177e4SLinus Torvalds if (unlikely(!anon_vma)) 981da177e4SLinus Torvalds return -ENOMEM; 991da177e4SLinus Torvalds allocated = anon_vma; 1001da177e4SLinus Torvalds locked = NULL; 1011da177e4SLinus Torvalds } 1021da177e4SLinus Torvalds 1031da177e4SLinus Torvalds /* page_table_lock to protect against threads */ 1041da177e4SLinus Torvalds spin_lock(&mm->page_table_lock); 1051da177e4SLinus Torvalds if (likely(!vma->anon_vma)) { 1061da177e4SLinus Torvalds vma->anon_vma = anon_vma; 1071da177e4SLinus Torvalds list_add(&vma->anon_vma_node, &anon_vma->head); 1081da177e4SLinus Torvalds allocated = NULL; 1091da177e4SLinus Torvalds } 1101da177e4SLinus Torvalds spin_unlock(&mm->page_table_lock); 1111da177e4SLinus Torvalds 1121da177e4SLinus Torvalds if (locked) 1131da177e4SLinus Torvalds spin_unlock(&locked->lock); 1141da177e4SLinus Torvalds if (unlikely(allocated)) 1151da177e4SLinus Torvalds anon_vma_free(allocated); 1161da177e4SLinus Torvalds } 1171da177e4SLinus Torvalds return 0; 1181da177e4SLinus Torvalds } 1191da177e4SLinus Torvalds 1201da177e4SLinus Torvalds void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) 1211da177e4SLinus Torvalds { 1221da177e4SLinus Torvalds BUG_ON(vma->anon_vma != next->anon_vma); 1231da177e4SLinus Torvalds list_del(&next->anon_vma_node); 1241da177e4SLinus Torvalds } 1251da177e4SLinus Torvalds 1261da177e4SLinus Torvalds void __anon_vma_link(struct vm_area_struct *vma) 1271da177e4SLinus Torvalds { 1281da177e4SLinus Torvalds struct anon_vma *anon_vma = vma->anon_vma; 1291da177e4SLinus Torvalds 1301da177e4SLinus Torvalds if (anon_vma) { 1311da177e4SLinus Torvalds list_add(&vma->anon_vma_node, &anon_vma->head); 1321da177e4SLinus Torvalds validate_anon_vma(vma); 1331da177e4SLinus Torvalds } 1341da177e4SLinus Torvalds } 1351da177e4SLinus Torvalds 1361da177e4SLinus Torvalds void anon_vma_link(struct vm_area_struct *vma) 1371da177e4SLinus Torvalds { 1381da177e4SLinus Torvalds struct anon_vma *anon_vma = vma->anon_vma; 1391da177e4SLinus Torvalds 1401da177e4SLinus Torvalds if (anon_vma) { 1411da177e4SLinus Torvalds spin_lock(&anon_vma->lock); 1421da177e4SLinus Torvalds list_add(&vma->anon_vma_node, &anon_vma->head); 1431da177e4SLinus Torvalds validate_anon_vma(vma); 1441da177e4SLinus Torvalds spin_unlock(&anon_vma->lock); 1451da177e4SLinus Torvalds } 1461da177e4SLinus Torvalds } 1471da177e4SLinus Torvalds 1481da177e4SLinus Torvalds void anon_vma_unlink(struct vm_area_struct *vma) 1491da177e4SLinus Torvalds { 1501da177e4SLinus Torvalds struct anon_vma *anon_vma = vma->anon_vma; 1511da177e4SLinus Torvalds int empty; 1521da177e4SLinus Torvalds 1531da177e4SLinus Torvalds if (!anon_vma) 1541da177e4SLinus Torvalds return; 1551da177e4SLinus Torvalds 1561da177e4SLinus Torvalds spin_lock(&anon_vma->lock); 1571da177e4SLinus Torvalds validate_anon_vma(vma); 1581da177e4SLinus Torvalds list_del(&vma->anon_vma_node); 1591da177e4SLinus Torvalds 1601da177e4SLinus Torvalds /* We must garbage collect the anon_vma if it's empty */ 1611da177e4SLinus Torvalds empty = list_empty(&anon_vma->head); 1621da177e4SLinus Torvalds spin_unlock(&anon_vma->lock); 1631da177e4SLinus Torvalds 1641da177e4SLinus Torvalds if (empty) 1651da177e4SLinus Torvalds anon_vma_free(anon_vma); 1661da177e4SLinus Torvalds } 1671da177e4SLinus Torvalds 1681da177e4SLinus Torvalds static void anon_vma_ctor(void *data, kmem_cache_t *cachep, unsigned long flags) 1691da177e4SLinus Torvalds { 1701da177e4SLinus Torvalds if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 1711da177e4SLinus Torvalds SLAB_CTOR_CONSTRUCTOR) { 1721da177e4SLinus Torvalds struct anon_vma *anon_vma = data; 1731da177e4SLinus Torvalds 1741da177e4SLinus Torvalds spin_lock_init(&anon_vma->lock); 1751da177e4SLinus Torvalds INIT_LIST_HEAD(&anon_vma->head); 1761da177e4SLinus Torvalds } 1771da177e4SLinus Torvalds } 1781da177e4SLinus Torvalds 1791da177e4SLinus Torvalds void __init anon_vma_init(void) 1801da177e4SLinus Torvalds { 1811da177e4SLinus Torvalds anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), 1821da177e4SLinus Torvalds 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL); 1831da177e4SLinus Torvalds } 1841da177e4SLinus Torvalds 1851da177e4SLinus Torvalds /* 1861da177e4SLinus Torvalds * Getting a lock on a stable anon_vma from a page off the LRU is 1871da177e4SLinus Torvalds * tricky: page_lock_anon_vma rely on RCU to guard against the races. 1881da177e4SLinus Torvalds */ 1891da177e4SLinus Torvalds static struct anon_vma *page_lock_anon_vma(struct page *page) 1901da177e4SLinus Torvalds { 1911da177e4SLinus Torvalds struct anon_vma *anon_vma = NULL; 1921da177e4SLinus Torvalds unsigned long anon_mapping; 1931da177e4SLinus Torvalds 1941da177e4SLinus Torvalds rcu_read_lock(); 1951da177e4SLinus Torvalds anon_mapping = (unsigned long) page->mapping; 1961da177e4SLinus Torvalds if (!(anon_mapping & PAGE_MAPPING_ANON)) 1971da177e4SLinus Torvalds goto out; 1981da177e4SLinus Torvalds if (!page_mapped(page)) 1991da177e4SLinus Torvalds goto out; 2001da177e4SLinus Torvalds 2011da177e4SLinus Torvalds anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); 2021da177e4SLinus Torvalds spin_lock(&anon_vma->lock); 2031da177e4SLinus Torvalds out: 2041da177e4SLinus Torvalds rcu_read_unlock(); 2051da177e4SLinus Torvalds return anon_vma; 2061da177e4SLinus Torvalds } 2071da177e4SLinus Torvalds 2081da177e4SLinus Torvalds /* 2091da177e4SLinus Torvalds * At what user virtual address is page expected in vma? 2101da177e4SLinus Torvalds */ 2111da177e4SLinus Torvalds static inline unsigned long 2121da177e4SLinus Torvalds vma_address(struct page *page, struct vm_area_struct *vma) 2131da177e4SLinus Torvalds { 2141da177e4SLinus Torvalds pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); 2151da177e4SLinus Torvalds unsigned long address; 2161da177e4SLinus Torvalds 2171da177e4SLinus Torvalds address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); 2181da177e4SLinus Torvalds if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { 2191da177e4SLinus Torvalds /* page should be within any vma from prio_tree_next */ 2201da177e4SLinus Torvalds BUG_ON(!PageAnon(page)); 2211da177e4SLinus Torvalds return -EFAULT; 2221da177e4SLinus Torvalds } 2231da177e4SLinus Torvalds return address; 2241da177e4SLinus Torvalds } 2251da177e4SLinus Torvalds 2261da177e4SLinus Torvalds /* 2271da177e4SLinus Torvalds * At what user virtual address is page expected in vma? checking that the 2281da177e4SLinus Torvalds * page matches the vma: currently only used by unuse_process, on anon pages. 2291da177e4SLinus Torvalds */ 2301da177e4SLinus Torvalds unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) 2311da177e4SLinus Torvalds { 2321da177e4SLinus Torvalds if (PageAnon(page)) { 2331da177e4SLinus Torvalds if ((void *)vma->anon_vma != 2341da177e4SLinus Torvalds (void *)page->mapping - PAGE_MAPPING_ANON) 2351da177e4SLinus Torvalds return -EFAULT; 2361da177e4SLinus Torvalds } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { 2371da177e4SLinus Torvalds if (vma->vm_file->f_mapping != page->mapping) 2381da177e4SLinus Torvalds return -EFAULT; 2391da177e4SLinus Torvalds } else 2401da177e4SLinus Torvalds return -EFAULT; 2411da177e4SLinus Torvalds return vma_address(page, vma); 2421da177e4SLinus Torvalds } 2431da177e4SLinus Torvalds 2441da177e4SLinus Torvalds /* 24581b4082dSNikita Danilov * Check that @page is mapped at @address into @mm. 24681b4082dSNikita Danilov * 247*b8072f09SHugh Dickins * On success returns with pte mapped and locked. 24881b4082dSNikita Danilov */ 249ceffc078SCarsten Otte pte_t *page_check_address(struct page *page, struct mm_struct *mm, 250c0718806SHugh Dickins unsigned long address, spinlock_t **ptlp) 25181b4082dSNikita Danilov { 25281b4082dSNikita Danilov pgd_t *pgd; 25381b4082dSNikita Danilov pud_t *pud; 25481b4082dSNikita Danilov pmd_t *pmd; 25581b4082dSNikita Danilov pte_t *pte; 256c0718806SHugh Dickins spinlock_t *ptl; 25781b4082dSNikita Danilov 25881b4082dSNikita Danilov pgd = pgd_offset(mm, address); 259c0718806SHugh Dickins if (!pgd_present(*pgd)) 260c0718806SHugh Dickins return NULL; 261c0718806SHugh Dickins 26281b4082dSNikita Danilov pud = pud_offset(pgd, address); 263c0718806SHugh Dickins if (!pud_present(*pud)) 264c0718806SHugh Dickins return NULL; 265c0718806SHugh Dickins 26681b4082dSNikita Danilov pmd = pmd_offset(pud, address); 267c0718806SHugh Dickins if (!pmd_present(*pmd)) 268c0718806SHugh Dickins return NULL; 269c0718806SHugh Dickins 27081b4082dSNikita Danilov pte = pte_offset_map(pmd, address); 271c0718806SHugh Dickins /* Make a quick check before getting the lock */ 272c0718806SHugh Dickins if (!pte_present(*pte)) { 27381b4082dSNikita Danilov pte_unmap(pte); 274c0718806SHugh Dickins return NULL; 27581b4082dSNikita Danilov } 276c0718806SHugh Dickins 2774c21e2f2SHugh Dickins ptl = pte_lockptr(mm, pmd); 278c0718806SHugh Dickins spin_lock(ptl); 279c0718806SHugh Dickins if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { 280c0718806SHugh Dickins *ptlp = ptl; 281c0718806SHugh Dickins return pte; 28281b4082dSNikita Danilov } 283c0718806SHugh Dickins pte_unmap_unlock(pte, ptl); 284c0718806SHugh Dickins return NULL; 28581b4082dSNikita Danilov } 28681b4082dSNikita Danilov 28781b4082dSNikita Danilov /* 2881da177e4SLinus Torvalds * Subfunctions of page_referenced: page_referenced_one called 2891da177e4SLinus Torvalds * repeatedly from either page_referenced_anon or page_referenced_file. 2901da177e4SLinus Torvalds */ 2911da177e4SLinus Torvalds static int page_referenced_one(struct page *page, 2921da177e4SLinus Torvalds struct vm_area_struct *vma, unsigned int *mapcount, int ignore_token) 2931da177e4SLinus Torvalds { 2941da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 2951da177e4SLinus Torvalds unsigned long address; 2961da177e4SLinus Torvalds pte_t *pte; 297c0718806SHugh Dickins spinlock_t *ptl; 2981da177e4SLinus Torvalds int referenced = 0; 2991da177e4SLinus Torvalds 3001da177e4SLinus Torvalds address = vma_address(page, vma); 3011da177e4SLinus Torvalds if (address == -EFAULT) 3021da177e4SLinus Torvalds goto out; 3031da177e4SLinus Torvalds 304c0718806SHugh Dickins pte = page_check_address(page, mm, address, &ptl); 305c0718806SHugh Dickins if (!pte) 306c0718806SHugh Dickins goto out; 307c0718806SHugh Dickins 3081da177e4SLinus Torvalds if (ptep_clear_flush_young(vma, address, pte)) 3091da177e4SLinus Torvalds referenced++; 3101da177e4SLinus Torvalds 311fcdae29aSRik Van Riel /* Pretend the page is referenced if the task has the 312fcdae29aSRik Van Riel swap token and is in the middle of a page fault. */ 313c0718806SHugh Dickins if (mm != current->mm && !ignore_token && has_swap_token(mm) && 314fcdae29aSRik Van Riel rwsem_is_locked(&mm->mmap_sem)) 3151da177e4SLinus Torvalds referenced++; 3161da177e4SLinus Torvalds 3171da177e4SLinus Torvalds (*mapcount)--; 318c0718806SHugh Dickins pte_unmap_unlock(pte, ptl); 3191da177e4SLinus Torvalds out: 3201da177e4SLinus Torvalds return referenced; 3211da177e4SLinus Torvalds } 3221da177e4SLinus Torvalds 3231da177e4SLinus Torvalds static int page_referenced_anon(struct page *page, int ignore_token) 3241da177e4SLinus Torvalds { 3251da177e4SLinus Torvalds unsigned int mapcount; 3261da177e4SLinus Torvalds struct anon_vma *anon_vma; 3271da177e4SLinus Torvalds struct vm_area_struct *vma; 3281da177e4SLinus Torvalds int referenced = 0; 3291da177e4SLinus Torvalds 3301da177e4SLinus Torvalds anon_vma = page_lock_anon_vma(page); 3311da177e4SLinus Torvalds if (!anon_vma) 3321da177e4SLinus Torvalds return referenced; 3331da177e4SLinus Torvalds 3341da177e4SLinus Torvalds mapcount = page_mapcount(page); 3351da177e4SLinus Torvalds list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { 3361da177e4SLinus Torvalds referenced += page_referenced_one(page, vma, &mapcount, 3371da177e4SLinus Torvalds ignore_token); 3381da177e4SLinus Torvalds if (!mapcount) 3391da177e4SLinus Torvalds break; 3401da177e4SLinus Torvalds } 3411da177e4SLinus Torvalds spin_unlock(&anon_vma->lock); 3421da177e4SLinus Torvalds return referenced; 3431da177e4SLinus Torvalds } 3441da177e4SLinus Torvalds 3451da177e4SLinus Torvalds /** 3461da177e4SLinus Torvalds * page_referenced_file - referenced check for object-based rmap 3471da177e4SLinus Torvalds * @page: the page we're checking references on. 3481da177e4SLinus Torvalds * 3491da177e4SLinus Torvalds * For an object-based mapped page, find all the places it is mapped and 3501da177e4SLinus Torvalds * check/clear the referenced flag. This is done by following the page->mapping 3511da177e4SLinus Torvalds * pointer, then walking the chain of vmas it holds. It returns the number 3521da177e4SLinus Torvalds * of references it found. 3531da177e4SLinus Torvalds * 3541da177e4SLinus Torvalds * This function is only called from page_referenced for object-based pages. 3551da177e4SLinus Torvalds */ 3561da177e4SLinus Torvalds static int page_referenced_file(struct page *page, int ignore_token) 3571da177e4SLinus Torvalds { 3581da177e4SLinus Torvalds unsigned int mapcount; 3591da177e4SLinus Torvalds struct address_space *mapping = page->mapping; 3601da177e4SLinus Torvalds pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); 3611da177e4SLinus Torvalds struct vm_area_struct *vma; 3621da177e4SLinus Torvalds struct prio_tree_iter iter; 3631da177e4SLinus Torvalds int referenced = 0; 3641da177e4SLinus Torvalds 3651da177e4SLinus Torvalds /* 3661da177e4SLinus Torvalds * The caller's checks on page->mapping and !PageAnon have made 3671da177e4SLinus Torvalds * sure that this is a file page: the check for page->mapping 3681da177e4SLinus Torvalds * excludes the case just before it gets set on an anon page. 3691da177e4SLinus Torvalds */ 3701da177e4SLinus Torvalds BUG_ON(PageAnon(page)); 3711da177e4SLinus Torvalds 3721da177e4SLinus Torvalds /* 3731da177e4SLinus Torvalds * The page lock not only makes sure that page->mapping cannot 3741da177e4SLinus Torvalds * suddenly be NULLified by truncation, it makes sure that the 3751da177e4SLinus Torvalds * structure at mapping cannot be freed and reused yet, 3761da177e4SLinus Torvalds * so we can safely take mapping->i_mmap_lock. 3771da177e4SLinus Torvalds */ 3781da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 3791da177e4SLinus Torvalds 3801da177e4SLinus Torvalds spin_lock(&mapping->i_mmap_lock); 3811da177e4SLinus Torvalds 3821da177e4SLinus Torvalds /* 3831da177e4SLinus Torvalds * i_mmap_lock does not stabilize mapcount at all, but mapcount 3841da177e4SLinus Torvalds * is more likely to be accurate if we note it after spinning. 3851da177e4SLinus Torvalds */ 3861da177e4SLinus Torvalds mapcount = page_mapcount(page); 3871da177e4SLinus Torvalds 3881da177e4SLinus Torvalds vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 3891da177e4SLinus Torvalds if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) 3901da177e4SLinus Torvalds == (VM_LOCKED|VM_MAYSHARE)) { 3911da177e4SLinus Torvalds referenced++; 3921da177e4SLinus Torvalds break; 3931da177e4SLinus Torvalds } 3941da177e4SLinus Torvalds referenced += page_referenced_one(page, vma, &mapcount, 3951da177e4SLinus Torvalds ignore_token); 3961da177e4SLinus Torvalds if (!mapcount) 3971da177e4SLinus Torvalds break; 3981da177e4SLinus Torvalds } 3991da177e4SLinus Torvalds 4001da177e4SLinus Torvalds spin_unlock(&mapping->i_mmap_lock); 4011da177e4SLinus Torvalds return referenced; 4021da177e4SLinus Torvalds } 4031da177e4SLinus Torvalds 4041da177e4SLinus Torvalds /** 4051da177e4SLinus Torvalds * page_referenced - test if the page was referenced 4061da177e4SLinus Torvalds * @page: the page to test 4071da177e4SLinus Torvalds * @is_locked: caller holds lock on the page 4081da177e4SLinus Torvalds * 4091da177e4SLinus Torvalds * Quick test_and_clear_referenced for all mappings to a page, 4101da177e4SLinus Torvalds * returns the number of ptes which referenced the page. 4111da177e4SLinus Torvalds */ 4121da177e4SLinus Torvalds int page_referenced(struct page *page, int is_locked, int ignore_token) 4131da177e4SLinus Torvalds { 4141da177e4SLinus Torvalds int referenced = 0; 4151da177e4SLinus Torvalds 4161da177e4SLinus Torvalds if (!swap_token_default_timeout) 4171da177e4SLinus Torvalds ignore_token = 1; 4181da177e4SLinus Torvalds 4191da177e4SLinus Torvalds if (page_test_and_clear_young(page)) 4201da177e4SLinus Torvalds referenced++; 4211da177e4SLinus Torvalds 4221da177e4SLinus Torvalds if (TestClearPageReferenced(page)) 4231da177e4SLinus Torvalds referenced++; 4241da177e4SLinus Torvalds 4251da177e4SLinus Torvalds if (page_mapped(page) && page->mapping) { 4261da177e4SLinus Torvalds if (PageAnon(page)) 4271da177e4SLinus Torvalds referenced += page_referenced_anon(page, ignore_token); 4281da177e4SLinus Torvalds else if (is_locked) 4291da177e4SLinus Torvalds referenced += page_referenced_file(page, ignore_token); 4301da177e4SLinus Torvalds else if (TestSetPageLocked(page)) 4311da177e4SLinus Torvalds referenced++; 4321da177e4SLinus Torvalds else { 4331da177e4SLinus Torvalds if (page->mapping) 4341da177e4SLinus Torvalds referenced += page_referenced_file(page, 4351da177e4SLinus Torvalds ignore_token); 4361da177e4SLinus Torvalds unlock_page(page); 4371da177e4SLinus Torvalds } 4381da177e4SLinus Torvalds } 4391da177e4SLinus Torvalds return referenced; 4401da177e4SLinus Torvalds } 4411da177e4SLinus Torvalds 4421da177e4SLinus Torvalds /** 4431da177e4SLinus Torvalds * page_add_anon_rmap - add pte mapping to an anonymous page 4441da177e4SLinus Torvalds * @page: the page to add the mapping to 4451da177e4SLinus Torvalds * @vma: the vm area in which the mapping is added 4461da177e4SLinus Torvalds * @address: the user virtual address mapped 4471da177e4SLinus Torvalds * 448*b8072f09SHugh Dickins * The caller needs to hold the pte lock. 4491da177e4SLinus Torvalds */ 4501da177e4SLinus Torvalds void page_add_anon_rmap(struct page *page, 4511da177e4SLinus Torvalds struct vm_area_struct *vma, unsigned long address) 4521da177e4SLinus Torvalds { 4532822c1aaSNick Piggin if (atomic_inc_and_test(&page->_mapcount)) { 4542822c1aaSNick Piggin struct anon_vma *anon_vma = vma->anon_vma; 4552822c1aaSNick Piggin 4562822c1aaSNick Piggin BUG_ON(!anon_vma); 4571da177e4SLinus Torvalds anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; 4582822c1aaSNick Piggin page->mapping = (struct address_space *) anon_vma; 4592822c1aaSNick Piggin 4604d7670e0SNick Piggin page->index = linear_page_index(vma, address); 4612822c1aaSNick Piggin 4621da177e4SLinus Torvalds inc_page_state(nr_mapped); 4631da177e4SLinus Torvalds } 4641da177e4SLinus Torvalds /* else checking page index and mapping is racy */ 4651da177e4SLinus Torvalds } 4661da177e4SLinus Torvalds 4671da177e4SLinus Torvalds /** 4681da177e4SLinus Torvalds * page_add_file_rmap - add pte mapping to a file page 4691da177e4SLinus Torvalds * @page: the page to add the mapping to 4701da177e4SLinus Torvalds * 471*b8072f09SHugh Dickins * The caller needs to hold the pte lock. 4721da177e4SLinus Torvalds */ 4731da177e4SLinus Torvalds void page_add_file_rmap(struct page *page) 4741da177e4SLinus Torvalds { 4751da177e4SLinus Torvalds BUG_ON(PageAnon(page)); 476b5810039SNick Piggin BUG_ON(!pfn_valid(page_to_pfn(page))); 4771da177e4SLinus Torvalds 4781da177e4SLinus Torvalds if (atomic_inc_and_test(&page->_mapcount)) 4791da177e4SLinus Torvalds inc_page_state(nr_mapped); 4801da177e4SLinus Torvalds } 4811da177e4SLinus Torvalds 4821da177e4SLinus Torvalds /** 4831da177e4SLinus Torvalds * page_remove_rmap - take down pte mapping from a page 4841da177e4SLinus Torvalds * @page: page to remove mapping from 4851da177e4SLinus Torvalds * 486*b8072f09SHugh Dickins * The caller needs to hold the pte lock. 4871da177e4SLinus Torvalds */ 4881da177e4SLinus Torvalds void page_remove_rmap(struct page *page) 4891da177e4SLinus Torvalds { 4901da177e4SLinus Torvalds if (atomic_add_negative(-1, &page->_mapcount)) { 4911da177e4SLinus Torvalds BUG_ON(page_mapcount(page) < 0); 4921da177e4SLinus Torvalds /* 4931da177e4SLinus Torvalds * It would be tidy to reset the PageAnon mapping here, 4941da177e4SLinus Torvalds * but that might overwrite a racing page_add_anon_rmap 4951da177e4SLinus Torvalds * which increments mapcount after us but sets mapping 4961da177e4SLinus Torvalds * before us: so leave the reset to free_hot_cold_page, 4971da177e4SLinus Torvalds * and remember that it's only reliable while mapped. 4981da177e4SLinus Torvalds * Leaving it set also helps swapoff to reinstate ptes 4991da177e4SLinus Torvalds * faster for those pages still in swapcache. 5001da177e4SLinus Torvalds */ 5011da177e4SLinus Torvalds if (page_test_and_clear_dirty(page)) 5021da177e4SLinus Torvalds set_page_dirty(page); 5031da177e4SLinus Torvalds dec_page_state(nr_mapped); 5041da177e4SLinus Torvalds } 5051da177e4SLinus Torvalds } 5061da177e4SLinus Torvalds 5071da177e4SLinus Torvalds /* 5081da177e4SLinus Torvalds * Subfunctions of try_to_unmap: try_to_unmap_one called 5091da177e4SLinus Torvalds * repeatedly from either try_to_unmap_anon or try_to_unmap_file. 5101da177e4SLinus Torvalds */ 5111da177e4SLinus Torvalds static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) 5121da177e4SLinus Torvalds { 5131da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 5141da177e4SLinus Torvalds unsigned long address; 5151da177e4SLinus Torvalds pte_t *pte; 5161da177e4SLinus Torvalds pte_t pteval; 517c0718806SHugh Dickins spinlock_t *ptl; 5181da177e4SLinus Torvalds int ret = SWAP_AGAIN; 5191da177e4SLinus Torvalds 5201da177e4SLinus Torvalds address = vma_address(page, vma); 5211da177e4SLinus Torvalds if (address == -EFAULT) 5221da177e4SLinus Torvalds goto out; 5231da177e4SLinus Torvalds 524c0718806SHugh Dickins pte = page_check_address(page, mm, address, &ptl); 525c0718806SHugh Dickins if (!pte) 52681b4082dSNikita Danilov goto out; 5271da177e4SLinus Torvalds 5281da177e4SLinus Torvalds /* 5291da177e4SLinus Torvalds * If the page is mlock()d, we cannot swap it out. 5301da177e4SLinus Torvalds * If it's recently referenced (perhaps page_referenced 5311da177e4SLinus Torvalds * skipped over this mm) then we should reactivate it. 532c3dce2d8SNick Piggin * 533c3dce2d8SNick Piggin * Pages belonging to VM_RESERVED regions should not happen here. 5341da177e4SLinus Torvalds */ 5351da177e4SLinus Torvalds if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) || 5361da177e4SLinus Torvalds ptep_clear_flush_young(vma, address, pte)) { 5371da177e4SLinus Torvalds ret = SWAP_FAIL; 5381da177e4SLinus Torvalds goto out_unmap; 5391da177e4SLinus Torvalds } 5401da177e4SLinus Torvalds 5411da177e4SLinus Torvalds /* Nuke the page table entry. */ 5421da177e4SLinus Torvalds flush_cache_page(vma, address, page_to_pfn(page)); 5431da177e4SLinus Torvalds pteval = ptep_clear_flush(vma, address, pte); 5441da177e4SLinus Torvalds 5451da177e4SLinus Torvalds /* Move the dirty bit to the physical page now the pte is gone. */ 5461da177e4SLinus Torvalds if (pte_dirty(pteval)) 5471da177e4SLinus Torvalds set_page_dirty(page); 5481da177e4SLinus Torvalds 549365e9c87SHugh Dickins /* Update high watermark before we lower rss */ 550365e9c87SHugh Dickins update_hiwater_rss(mm); 551365e9c87SHugh Dickins 5521da177e4SLinus Torvalds if (PageAnon(page)) { 5534c21e2f2SHugh Dickins swp_entry_t entry = { .val = page_private(page) }; 5541da177e4SLinus Torvalds /* 5551da177e4SLinus Torvalds * Store the swap location in the pte. 5561da177e4SLinus Torvalds * See handle_pte_fault() ... 5571da177e4SLinus Torvalds */ 5581da177e4SLinus Torvalds BUG_ON(!PageSwapCache(page)); 5591da177e4SLinus Torvalds swap_duplicate(entry); 5601da177e4SLinus Torvalds if (list_empty(&mm->mmlist)) { 5611da177e4SLinus Torvalds spin_lock(&mmlist_lock); 562f412ac08SHugh Dickins if (list_empty(&mm->mmlist)) 5631da177e4SLinus Torvalds list_add(&mm->mmlist, &init_mm.mmlist); 5641da177e4SLinus Torvalds spin_unlock(&mmlist_lock); 5651da177e4SLinus Torvalds } 5661da177e4SLinus Torvalds set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); 5671da177e4SLinus Torvalds BUG_ON(pte_file(*pte)); 5681da177e4SLinus Torvalds dec_mm_counter(mm, anon_rss); 5694294621fSHugh Dickins } else 5704294621fSHugh Dickins dec_mm_counter(mm, file_rss); 5711da177e4SLinus Torvalds 5721da177e4SLinus Torvalds page_remove_rmap(page); 5731da177e4SLinus Torvalds page_cache_release(page); 5741da177e4SLinus Torvalds 5751da177e4SLinus Torvalds out_unmap: 576c0718806SHugh Dickins pte_unmap_unlock(pte, ptl); 5771da177e4SLinus Torvalds out: 5781da177e4SLinus Torvalds return ret; 5791da177e4SLinus Torvalds } 5801da177e4SLinus Torvalds 5811da177e4SLinus Torvalds /* 5821da177e4SLinus Torvalds * objrmap doesn't work for nonlinear VMAs because the assumption that 5831da177e4SLinus Torvalds * offset-into-file correlates with offset-into-virtual-addresses does not hold. 5841da177e4SLinus Torvalds * Consequently, given a particular page and its ->index, we cannot locate the 5851da177e4SLinus Torvalds * ptes which are mapping that page without an exhaustive linear search. 5861da177e4SLinus Torvalds * 5871da177e4SLinus Torvalds * So what this code does is a mini "virtual scan" of each nonlinear VMA which 5881da177e4SLinus Torvalds * maps the file to which the target page belongs. The ->vm_private_data field 5891da177e4SLinus Torvalds * holds the current cursor into that scan. Successive searches will circulate 5901da177e4SLinus Torvalds * around the vma's virtual address space. 5911da177e4SLinus Torvalds * 5921da177e4SLinus Torvalds * So as more replacement pressure is applied to the pages in a nonlinear VMA, 5931da177e4SLinus Torvalds * more scanning pressure is placed against them as well. Eventually pages 5941da177e4SLinus Torvalds * will become fully unmapped and are eligible for eviction. 5951da177e4SLinus Torvalds * 5961da177e4SLinus Torvalds * For very sparsely populated VMAs this is a little inefficient - chances are 5971da177e4SLinus Torvalds * there there won't be many ptes located within the scan cluster. In this case 5981da177e4SLinus Torvalds * maybe we could scan further - to the end of the pte page, perhaps. 5991da177e4SLinus Torvalds */ 6001da177e4SLinus Torvalds #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) 6011da177e4SLinus Torvalds #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) 6021da177e4SLinus Torvalds 6031da177e4SLinus Torvalds static void try_to_unmap_cluster(unsigned long cursor, 6041da177e4SLinus Torvalds unsigned int *mapcount, struct vm_area_struct *vma) 6051da177e4SLinus Torvalds { 6061da177e4SLinus Torvalds struct mm_struct *mm = vma->vm_mm; 6071da177e4SLinus Torvalds pgd_t *pgd; 6081da177e4SLinus Torvalds pud_t *pud; 6091da177e4SLinus Torvalds pmd_t *pmd; 610c0718806SHugh Dickins pte_t *pte; 6111da177e4SLinus Torvalds pte_t pteval; 612c0718806SHugh Dickins spinlock_t *ptl; 6131da177e4SLinus Torvalds struct page *page; 6141da177e4SLinus Torvalds unsigned long address; 6151da177e4SLinus Torvalds unsigned long end; 6161da177e4SLinus Torvalds unsigned long pfn; 6171da177e4SLinus Torvalds 6181da177e4SLinus Torvalds address = (vma->vm_start + cursor) & CLUSTER_MASK; 6191da177e4SLinus Torvalds end = address + CLUSTER_SIZE; 6201da177e4SLinus Torvalds if (address < vma->vm_start) 6211da177e4SLinus Torvalds address = vma->vm_start; 6221da177e4SLinus Torvalds if (end > vma->vm_end) 6231da177e4SLinus Torvalds end = vma->vm_end; 6241da177e4SLinus Torvalds 6251da177e4SLinus Torvalds pgd = pgd_offset(mm, address); 6261da177e4SLinus Torvalds if (!pgd_present(*pgd)) 627c0718806SHugh Dickins return; 6281da177e4SLinus Torvalds 6291da177e4SLinus Torvalds pud = pud_offset(pgd, address); 6301da177e4SLinus Torvalds if (!pud_present(*pud)) 631c0718806SHugh Dickins return; 6321da177e4SLinus Torvalds 6331da177e4SLinus Torvalds pmd = pmd_offset(pud, address); 6341da177e4SLinus Torvalds if (!pmd_present(*pmd)) 635c0718806SHugh Dickins return; 636c0718806SHugh Dickins 637c0718806SHugh Dickins pte = pte_offset_map_lock(mm, pmd, address, &ptl); 6381da177e4SLinus Torvalds 639365e9c87SHugh Dickins /* Update high watermark before we lower rss */ 640365e9c87SHugh Dickins update_hiwater_rss(mm); 641365e9c87SHugh Dickins 642c0718806SHugh Dickins for (; address < end; pte++, address += PAGE_SIZE) { 6431da177e4SLinus Torvalds if (!pte_present(*pte)) 6441da177e4SLinus Torvalds continue; 6451da177e4SLinus Torvalds 6461da177e4SLinus Torvalds pfn = pte_pfn(*pte); 647b5810039SNick Piggin if (unlikely(!pfn_valid(pfn))) { 648b5810039SNick Piggin print_bad_pte(vma, *pte, address); 6491da177e4SLinus Torvalds continue; 650b5810039SNick Piggin } 6511da177e4SLinus Torvalds 6521da177e4SLinus Torvalds page = pfn_to_page(pfn); 6531da177e4SLinus Torvalds BUG_ON(PageAnon(page)); 6541da177e4SLinus Torvalds 6551da177e4SLinus Torvalds if (ptep_clear_flush_young(vma, address, pte)) 6561da177e4SLinus Torvalds continue; 6571da177e4SLinus Torvalds 6581da177e4SLinus Torvalds /* Nuke the page table entry. */ 6591da177e4SLinus Torvalds flush_cache_page(vma, address, pfn); 6601da177e4SLinus Torvalds pteval = ptep_clear_flush(vma, address, pte); 6611da177e4SLinus Torvalds 6621da177e4SLinus Torvalds /* If nonlinear, store the file page offset in the pte. */ 6631da177e4SLinus Torvalds if (page->index != linear_page_index(vma, address)) 6641da177e4SLinus Torvalds set_pte_at(mm, address, pte, pgoff_to_pte(page->index)); 6651da177e4SLinus Torvalds 6661da177e4SLinus Torvalds /* Move the dirty bit to the physical page now the pte is gone. */ 6671da177e4SLinus Torvalds if (pte_dirty(pteval)) 6681da177e4SLinus Torvalds set_page_dirty(page); 6691da177e4SLinus Torvalds 6701da177e4SLinus Torvalds page_remove_rmap(page); 6711da177e4SLinus Torvalds page_cache_release(page); 6724294621fSHugh Dickins dec_mm_counter(mm, file_rss); 6731da177e4SLinus Torvalds (*mapcount)--; 6741da177e4SLinus Torvalds } 675c0718806SHugh Dickins pte_unmap_unlock(pte - 1, ptl); 6761da177e4SLinus Torvalds } 6771da177e4SLinus Torvalds 6781da177e4SLinus Torvalds static int try_to_unmap_anon(struct page *page) 6791da177e4SLinus Torvalds { 6801da177e4SLinus Torvalds struct anon_vma *anon_vma; 6811da177e4SLinus Torvalds struct vm_area_struct *vma; 6821da177e4SLinus Torvalds int ret = SWAP_AGAIN; 6831da177e4SLinus Torvalds 6841da177e4SLinus Torvalds anon_vma = page_lock_anon_vma(page); 6851da177e4SLinus Torvalds if (!anon_vma) 6861da177e4SLinus Torvalds return ret; 6871da177e4SLinus Torvalds 6881da177e4SLinus Torvalds list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { 6891da177e4SLinus Torvalds ret = try_to_unmap_one(page, vma); 6901da177e4SLinus Torvalds if (ret == SWAP_FAIL || !page_mapped(page)) 6911da177e4SLinus Torvalds break; 6921da177e4SLinus Torvalds } 6931da177e4SLinus Torvalds spin_unlock(&anon_vma->lock); 6941da177e4SLinus Torvalds return ret; 6951da177e4SLinus Torvalds } 6961da177e4SLinus Torvalds 6971da177e4SLinus Torvalds /** 6981da177e4SLinus Torvalds * try_to_unmap_file - unmap file page using the object-based rmap method 6991da177e4SLinus Torvalds * @page: the page to unmap 7001da177e4SLinus Torvalds * 7011da177e4SLinus Torvalds * Find all the mappings of a page using the mapping pointer and the vma chains 7021da177e4SLinus Torvalds * contained in the address_space struct it points to. 7031da177e4SLinus Torvalds * 7041da177e4SLinus Torvalds * This function is only called from try_to_unmap for object-based pages. 7051da177e4SLinus Torvalds */ 7061da177e4SLinus Torvalds static int try_to_unmap_file(struct page *page) 7071da177e4SLinus Torvalds { 7081da177e4SLinus Torvalds struct address_space *mapping = page->mapping; 7091da177e4SLinus Torvalds pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); 7101da177e4SLinus Torvalds struct vm_area_struct *vma; 7111da177e4SLinus Torvalds struct prio_tree_iter iter; 7121da177e4SLinus Torvalds int ret = SWAP_AGAIN; 7131da177e4SLinus Torvalds unsigned long cursor; 7141da177e4SLinus Torvalds unsigned long max_nl_cursor = 0; 7151da177e4SLinus Torvalds unsigned long max_nl_size = 0; 7161da177e4SLinus Torvalds unsigned int mapcount; 7171da177e4SLinus Torvalds 7181da177e4SLinus Torvalds spin_lock(&mapping->i_mmap_lock); 7191da177e4SLinus Torvalds vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { 7201da177e4SLinus Torvalds ret = try_to_unmap_one(page, vma); 7211da177e4SLinus Torvalds if (ret == SWAP_FAIL || !page_mapped(page)) 7221da177e4SLinus Torvalds goto out; 7231da177e4SLinus Torvalds } 7241da177e4SLinus Torvalds 7251da177e4SLinus Torvalds if (list_empty(&mapping->i_mmap_nonlinear)) 7261da177e4SLinus Torvalds goto out; 7271da177e4SLinus Torvalds 7281da177e4SLinus Torvalds list_for_each_entry(vma, &mapping->i_mmap_nonlinear, 7291da177e4SLinus Torvalds shared.vm_set.list) { 7301da177e4SLinus Torvalds if (vma->vm_flags & (VM_LOCKED|VM_RESERVED)) 7311da177e4SLinus Torvalds continue; 7321da177e4SLinus Torvalds cursor = (unsigned long) vma->vm_private_data; 7331da177e4SLinus Torvalds if (cursor > max_nl_cursor) 7341da177e4SLinus Torvalds max_nl_cursor = cursor; 7351da177e4SLinus Torvalds cursor = vma->vm_end - vma->vm_start; 7361da177e4SLinus Torvalds if (cursor > max_nl_size) 7371da177e4SLinus Torvalds max_nl_size = cursor; 7381da177e4SLinus Torvalds } 7391da177e4SLinus Torvalds 7401da177e4SLinus Torvalds if (max_nl_size == 0) { /* any nonlinears locked or reserved */ 7411da177e4SLinus Torvalds ret = SWAP_FAIL; 7421da177e4SLinus Torvalds goto out; 7431da177e4SLinus Torvalds } 7441da177e4SLinus Torvalds 7451da177e4SLinus Torvalds /* 7461da177e4SLinus Torvalds * We don't try to search for this page in the nonlinear vmas, 7471da177e4SLinus Torvalds * and page_referenced wouldn't have found it anyway. Instead 7481da177e4SLinus Torvalds * just walk the nonlinear vmas trying to age and unmap some. 7491da177e4SLinus Torvalds * The mapcount of the page we came in with is irrelevant, 7501da177e4SLinus Torvalds * but even so use it as a guide to how hard we should try? 7511da177e4SLinus Torvalds */ 7521da177e4SLinus Torvalds mapcount = page_mapcount(page); 7531da177e4SLinus Torvalds if (!mapcount) 7541da177e4SLinus Torvalds goto out; 7551da177e4SLinus Torvalds cond_resched_lock(&mapping->i_mmap_lock); 7561da177e4SLinus Torvalds 7571da177e4SLinus Torvalds max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK; 7581da177e4SLinus Torvalds if (max_nl_cursor == 0) 7591da177e4SLinus Torvalds max_nl_cursor = CLUSTER_SIZE; 7601da177e4SLinus Torvalds 7611da177e4SLinus Torvalds do { 7621da177e4SLinus Torvalds list_for_each_entry(vma, &mapping->i_mmap_nonlinear, 7631da177e4SLinus Torvalds shared.vm_set.list) { 7641da177e4SLinus Torvalds if (vma->vm_flags & (VM_LOCKED|VM_RESERVED)) 7651da177e4SLinus Torvalds continue; 7661da177e4SLinus Torvalds cursor = (unsigned long) vma->vm_private_data; 767839b9685SHugh Dickins while ( cursor < max_nl_cursor && 7681da177e4SLinus Torvalds cursor < vma->vm_end - vma->vm_start) { 7691da177e4SLinus Torvalds try_to_unmap_cluster(cursor, &mapcount, vma); 7701da177e4SLinus Torvalds cursor += CLUSTER_SIZE; 7711da177e4SLinus Torvalds vma->vm_private_data = (void *) cursor; 7721da177e4SLinus Torvalds if ((int)mapcount <= 0) 7731da177e4SLinus Torvalds goto out; 7741da177e4SLinus Torvalds } 7751da177e4SLinus Torvalds vma->vm_private_data = (void *) max_nl_cursor; 7761da177e4SLinus Torvalds } 7771da177e4SLinus Torvalds cond_resched_lock(&mapping->i_mmap_lock); 7781da177e4SLinus Torvalds max_nl_cursor += CLUSTER_SIZE; 7791da177e4SLinus Torvalds } while (max_nl_cursor <= max_nl_size); 7801da177e4SLinus Torvalds 7811da177e4SLinus Torvalds /* 7821da177e4SLinus Torvalds * Don't loop forever (perhaps all the remaining pages are 7831da177e4SLinus Torvalds * in locked vmas). Reset cursor on all unreserved nonlinear 7841da177e4SLinus Torvalds * vmas, now forgetting on which ones it had fallen behind. 7851da177e4SLinus Torvalds */ 7861da177e4SLinus Torvalds list_for_each_entry(vma, &mapping->i_mmap_nonlinear, 7871da177e4SLinus Torvalds shared.vm_set.list) { 7881da177e4SLinus Torvalds if (!(vma->vm_flags & VM_RESERVED)) 7891da177e4SLinus Torvalds vma->vm_private_data = NULL; 7901da177e4SLinus Torvalds } 7911da177e4SLinus Torvalds out: 7921da177e4SLinus Torvalds spin_unlock(&mapping->i_mmap_lock); 7931da177e4SLinus Torvalds return ret; 7941da177e4SLinus Torvalds } 7951da177e4SLinus Torvalds 7961da177e4SLinus Torvalds /** 7971da177e4SLinus Torvalds * try_to_unmap - try to remove all page table mappings to a page 7981da177e4SLinus Torvalds * @page: the page to get unmapped 7991da177e4SLinus Torvalds * 8001da177e4SLinus Torvalds * Tries to remove all the page table entries which are mapping this 8011da177e4SLinus Torvalds * page, used in the pageout path. Caller must hold the page lock. 8021da177e4SLinus Torvalds * Return values are: 8031da177e4SLinus Torvalds * 8041da177e4SLinus Torvalds * SWAP_SUCCESS - we succeeded in removing all mappings 8051da177e4SLinus Torvalds * SWAP_AGAIN - we missed a mapping, try again later 8061da177e4SLinus Torvalds * SWAP_FAIL - the page is unswappable 8071da177e4SLinus Torvalds */ 8081da177e4SLinus Torvalds int try_to_unmap(struct page *page) 8091da177e4SLinus Torvalds { 8101da177e4SLinus Torvalds int ret; 8111da177e4SLinus Torvalds 8121da177e4SLinus Torvalds BUG_ON(!PageLocked(page)); 8131da177e4SLinus Torvalds 8141da177e4SLinus Torvalds if (PageAnon(page)) 8151da177e4SLinus Torvalds ret = try_to_unmap_anon(page); 8161da177e4SLinus Torvalds else 8171da177e4SLinus Torvalds ret = try_to_unmap_file(page); 8181da177e4SLinus Torvalds 8191da177e4SLinus Torvalds if (!page_mapped(page)) 8201da177e4SLinus Torvalds ret = SWAP_SUCCESS; 8211da177e4SLinus Torvalds return ret; 8221da177e4SLinus Torvalds } 82381b4082dSNikita Danilov 824