/* * mm/rmap.c - physical to virtual reverse mappings * * Copyright 2001, Rik van Riel <riel@conectiva.com.br> * Released under the General Public License (GPL). * * Simple, low overhead reverse mapping scheme. * Please try to keep this thing as modular as possible. * * Provides methods for unmapping each kind of mapped page: * the anon methods track anonymous pages, and * the file methods track pages belonging to an inode. * * Original design by Rik van Riel <riel@conectiva.com.br> 2001 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004 */ /* * Lock ordering in mm: * * inode->i_mutex (while writing or truncating, not reading or faulting) * inode->i_alloc_sem * * When a page fault occurs in writing from user to file, down_read * of mmap_sem nests within i_mutex; in sys_msync, i_mutex nests within * down_read of mmap_sem; i_mutex and down_write of mmap_sem are never * taken together; in truncation, i_mutex is taken outermost. * * mm->mmap_sem * page->flags PG_locked (lock_page) * mapping->i_mmap_lock * anon_vma->lock * mm->page_table_lock or pte_lock * zone->lru_lock (in mark_page_accessed, isolate_lru_page) * swap_lock (in swap_duplicate, swap_info_get) * mmlist_lock (in mmput, drain_mmlist and others) * mapping->private_lock (in __set_page_dirty_buffers) * inode_lock (in set_page_dirty's __mark_inode_dirty) * sb_lock (within inode_lock in fs/fs-writeback.c) * mapping->tree_lock (widely used, in set_page_dirty, * in arch-dependent flush_dcache_mmap_lock, * within inode_lock in __sync_single_inode) */ #include <linux/mm.h>#include <linux/pagemap.h>#include <linux/swap.h>#include <linux/swapops.h>#include <linux/slab.h>#include <linux/init.h>#include <linux/rmap.h>#include <linux/rcupdate.h>#include <linux/module.h> #include <asm/tlbflush.h> struct kmem_cache *anon_vma_cachep; static inline void validate_anon_vma(struct vm_area_struct *find_vma){#ifdef CONFIG_DEBUG_VM struct anon_vma *anon_vma = find_vma->anon_vma; struct vm_area_struct *vma; unsigned int mapcount = 0; int found = 0; list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { mapcount++; BUG_ON(mapcount > 100000); if (vma == find_vma) found = 1; } BUG_ON(!found);#endif} /* This must be called under the mmap_sem. */int anon_vma_prepare(struct vm_area_struct *vma){ struct anon_vma *anon_vma = vma->anon_vma; might_sleep(); if (unlikely(!anon_vma)) { struct mm_struct *mm = vma->vm_mm; struct anon_vma *allocated, *locked; anon_vma = find_mergeable_anon_vma(vma); if (anon_vma) { allocated = NULL; locked = anon_vma; spin_lock(&locked->lock); } else { anon_vma = anon_vma_alloc(); if (unlikely(!anon_vma)) return -ENOMEM; allocated = anon_vma; locked = NULL; } /* page_table_lock to protect against threads */ spin_lock(&mm->page_table_lock); if (likely(!vma->anon_vma)) { vma->anon_vma = anon_vma; list_add(&vma->anon_vma_node, &anon_vma->head); allocated = NULL; } spin_unlock(&mm->page_table_lock); if (locked) spin_unlock(&locked->lock); if (unlikely(allocated)) anon_vma_free(allocated); } return 0;} void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next){ BUG_ON(vma->anon_vma != next->anon_vma); list_del(&next->anon_vma_node);} void __anon_vma_link(struct vm_area_struct *vma){ struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) { list_add(&vma->anon_vma_node, &anon_vma->head); validate_anon_vma(vma); }} void anon_vma_link(struct vm_area_struct *vma){ struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) { spin_lock(&anon_vma->lock); list_add(&vma->anon_vma_node, &anon_vma->head); validate_anon_vma(vma); spin_unlock(&anon_vma->lock); }} void anon_vma_unlink(struct vm_area_struct *vma){ struct anon_vma *anon_vma = vma->anon_vma; int empty; if (!anon_vma) return; spin_lock(&anon_vma->lock); validate_anon_vma(vma); list_del(&vma->anon_vma_node); /* We must garbage collect the anon_vma if it's empty */ empty = list_empty(&anon_vma->head); spin_unlock(&anon_vma->lock); if (empty) anon_vma_free(anon_vma);} static void anon_vma_ctor(void *data, struct kmem_cache *cachep, unsigned long flags){ if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) { struct anon_vma *anon_vma = data; spin_lock_init(&anon_vma->lock); INIT_LIST_HEAD(&anon_vma->head); }} void __init anon_vma_init(void){ anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL);} /* * Getting a lock on a stable anon_vma from a page off the LRU is * tricky: page_lock_anon_vma rely on RCU to guard against the races. */static struct anon_vma *page_lock_anon_vma(struct page *page){ struct anon_vma *anon_vma = NULL; unsigned long anon_mapping; rcu_read_lock(); anon_mapping = (unsigned long) page->mapping; if (!(anon_mapping & PAGE_MAPPING_ANON)) goto out; if (!page_mapped(page)) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock);out: rcu_read_unlock(); return anon_vma;} #ifdef CONFIG_MIGRATION/* * Remove an anonymous page from swap replacing the swap pte's * through real pte's pointing to valid pages and then releasing * the page from the swap cache. * * Must hold page lock on page and mmap_sem of one vma that contains * the page. */void remove_from_swap(struct page *page){ struct anon_vma *anon_vma; struct vm_area_struct *vma; unsigned long mapping; if (!PageSwapCache(page)) return; mapping = (unsigned long)page->mapping; if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) return; /* * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. */ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) remove_vma_swap(vma, page); spin_unlock(&anon_vma->lock); delete_from_swap_cache(page);}EXPORT_SYMBOL(remove_from_swap);#endif /* * At what user virtual address is page expected in vma? */static inline unsigned longvma_address(struct page *page, struct vm_area_struct *vma){ pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); unsigned long address; address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { /* page should be within any vma from prio_tree_next */ BUG_ON(!PageAnon(page)); return -EFAULT; } return address;} /* * At what user virtual address is page expected in vma? checking that the * page matches the vma: currently only used on anon pages, by unuse_vma; */unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma){ if (PageAnon(page)) { if ((void *)vma->anon_vma != (void *)page->mapping - PAGE_MAPPING_ANON) return -EFAULT; } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping) return -EFAULT; } else return -EFAULT; return vma_address(page, vma);} /* * Check that @page is mapped at @address into @mm. * * On success returns with pte mapped and locked. */pte_t *page_check_address(struct page *page, struct mm_struct *mm, unsigned long address, spinlock_t **ptlp){ pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *pte; spinlock_t *ptl; pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) return NULL; pud = pud_offset(pgd, address); if (!pud_present(*pud)) return NULL; pmd = pmd_offset(pud, address); if (!pmd_present(*pmd)) return NULL; pte = pte_offset_map(pmd, address); /* Make a quick check before getting the lock */ if (!pte_present(*pte)) { pte_unmap(pte); return NULL; } ptl = pte_lockptr(mm, pmd); spin_lock(ptl); if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { *ptlp = ptl; return pte; } pte_unmap_unlock(pte, ptl); return NULL;} /* * Subfunctions of page_referenced: page_referenced_one called * repeatedly from either page_referenced_anon or page_referenced_file. */static int page_referenced_one(struct page *page, struct vm_area_struct *vma, unsigned int *mapcount){ struct mm_struct *mm = vma->vm_mm; unsigned long address; pte_t *pte; spinlock_t *ptl; int referenced = 0; address = vma_address(page, vma); if (address == -EFAULT) goto out; pte = page_check_address(page, mm, address, &ptl); if (!pte) goto out; if (ptep_clear_flush_young(vma, address, pte)) referenced++; /* Pretend the page is referenced if the task has the swap token and is in the middle of a page fault. */ if (mm != current->mm && has_swap_token(mm) && rwsem_is_locked(&mm->mmap_sem)) referenced++; (*mapcount)--; pte_unmap_unlock(pte, ptl);out: return referenced;} static int page_referenced_anon(struct page *page){ unsigned int mapcount; struct anon_vma *anon_vma; struct vm_area_struct *vma; int referenced = 0; anon_vma = page_lock_anon_vma(page); if (!anon_vma) return referenced; mapcount = page_mapcount(page); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { referenced += page_referenced_one(page, vma, &mapcount); if (!mapcount) break; } spin_unlock(&anon_vma->lock); return referenced;} /** * page_referenced_file - referenced check for object-based rmap * @page: the page we're checking references on. * * For an object-based mapped page, find all the places it is mapped and * check/clear the referenced flag. This is done by following the page->mapping * pointer, then walking the chain of vmas it holds. It returns the number * of references it found. * * This function is only called from page_referenced for object-based pages. */static int page_referenced_file(struct page *page){ unsigned int mapcount; struct address_space *mapping = page->mapping; pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); struct vm_area_struct *vma; struct prio_tree_iter iter; int referenced = 0; /* * The caller's checks on page->mapping and !PageAnon have made * sure that this is a file page: the check for page->mapping * excludes the case just before it gets set on an anon page. */ BUG_ON(PageAnon(page)); /* * The page lock not only makes sure that page->mapping cannot * suddenly be NULLified by truncation, it makes sure that the * structure at mapping cannot be freed and reused yet, * so we can safely take mapping->i_mmap_lock. */ BUG_ON(!PageLocked(page)); spin_lock(&mapping->i_mmap_lock); /* * i_mmap_lock does not stabilize mapcount at all, but mapcount * is more likely to be accurate if we note it after spinning. */ mapcount = page_mapcount(page); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) == (VM_LOCKED|VM_MAYSHARE)) { referenced++; break; } referenced += page_referenced_one(page, vma, &mapcount); if (!mapcount) break; } spin_unlock(&mapping->i_mmap_lock); return referenced;} /** * page_referenced - test if the page was referenced * @page: the page to test * @is_locked: caller holds lock on the page * * Quick test_and_clear_referenced for all mappings to a page, * returns the number of ptes which referenced the page. */int page_referenced(struct page *page, int is_locked){ int referenced = 0; if (page_test_and_clear_young(page)) referenced++; if (TestClearPageReferenced(page)) referenced++; if (page_mapped(page) && page->mapping) { if (PageAnon(page)) referenced += page_referenced_anon(page); else if (is_locked) referenced += page_referenced_file(page); else if (TestSetPageLocked(page)) referenced++; else { if (page->mapping) referenced += page_referenced_file(page); unlock_page(page); } } return referenced;} /** * page_set_anon_rmap - setup new anonymous rmap * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped */static void __page_set_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address){ struct anon_vma *anon_vma = vma->anon_vma; BUG_ON(!anon_vma); anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; page->mapping = (struct address_space *) anon_vma; page->index = linear_page_index(vma, address); /* * nr_mapped state can be updated without turning off * interrupts because it is not modified via interrupt. */ __inc_page_state(nr_mapped);} /** * page_add_anon_rmap - add pte mapping to an anonymous pageLines 1–500 of 881. 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/* * mm/rmap.c - physical to virtual reverse mappings * * Copyright 2001, Rik van Riel <riel@conectiva.com.br> * Released under the General Public License (GPL). * * Simple, low overhead reverse mapping scheme. * Please try to keep this thing as modular as possible. * * Provides methods for unmapping each kind of mapped page: * the anon methods track anonymous pages, and * the file methods track pages belonging to an inode. * * Original design by Rik van Riel <riel@conectiva.com.br> 2001 * File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004 * Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004 * Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004 */ /* * Lock ordering in mm: * * inode->i_mutex (while writing or truncating, not reading or faulting) * inode->i_alloc_sem * * When a page fault occurs in writing from user to file, down_read * of mmap_sem nests within i_mutex; in sys_msync, i_mutex nests within * down_read of mmap_sem; i_mutex and down_write of mmap_sem are never * taken together; in truncation, i_mutex is taken outermost. * * mm->mmap_sem * page->flags PG_locked (lock_page) * mapping->i_mmap_lock * anon_vma->lock * mm->page_table_lock or pte_lock * zone->lru_lock (in mark_page_accessed, isolate_lru_page) * swap_lock (in swap_duplicate, swap_info_get) * mmlist_lock (in mmput, drain_mmlist and others) * mapping->private_lock (in __set_page_dirty_buffers) * inode_lock (in set_page_dirty's __mark_inode_dirty) * sb_lock (within inode_lock in fs/fs-writeback.c) * mapping->tree_lock (widely used, in set_page_dirty, * in arch-dependent flush_dcache_mmap_lock, * within inode_lock in __sync_single_inode) */ #include <linux/mm.h> #include <linux/pagemap.h> #include <linux/swap.h> #include <linux/swapops.h> #include <linux/slab.h> #include <linux/init.h> #include <linux/rmap.h> #include <linux/rcupdate.h> #include <linux/module.h> #include <asm/tlbflush.h> struct kmem_cache *anon_vma_cachep; static inline void validate_anon_vma(struct vm_area_struct *find_vma) { #ifdef CONFIG_DEBUG_VM struct anon_vma *anon_vma = find_vma->anon_vma; struct vm_area_struct *vma; unsigned int mapcount = 0; int found = 0; list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { mapcount++; BUG_ON(mapcount > 100000); if (vma == find_vma) found = 1; } BUG_ON(!found); #endif } /* This must be called under the mmap_sem. */ int anon_vma_prepare(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; might_sleep(); if (unlikely(!anon_vma)) { struct mm_struct *mm = vma->vm_mm; struct anon_vma *allocated, *locked; anon_vma = find_mergeable_anon_vma(vma); if (anon_vma) { allocated = NULL; locked = anon_vma; spin_lock(&locked->lock); } else { anon_vma = anon_vma_alloc(); if (unlikely(!anon_vma)) return -ENOMEM; allocated = anon_vma; locked = NULL; } /* page_table_lock to protect against threads */ spin_lock(&mm->page_table_lock); if (likely(!vma->anon_vma)) { vma->anon_vma = anon_vma; list_add(&vma->anon_vma_node, &anon_vma->head); allocated = NULL; } spin_unlock(&mm->page_table_lock); if (locked) spin_unlock(&locked->lock); if (unlikely(allocated)) anon_vma_free(allocated); } return 0; } void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next) { BUG_ON(vma->anon_vma != next->anon_vma); list_del(&next->anon_vma_node); } void __anon_vma_link(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) { list_add(&vma->anon_vma_node, &anon_vma->head); validate_anon_vma(vma); } } void anon_vma_link(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; if (anon_vma) { spin_lock(&anon_vma->lock); list_add(&vma->anon_vma_node, &anon_vma->head); validate_anon_vma(vma); spin_unlock(&anon_vma->lock); } } void anon_vma_unlink(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; int empty; if (!anon_vma) return; spin_lock(&anon_vma->lock); validate_anon_vma(vma); list_del(&vma->anon_vma_node); /* We must garbage collect the anon_vma if it's empty */ empty = list_empty(&anon_vma->head); spin_unlock(&anon_vma->lock); if (empty) anon_vma_free(anon_vma); } static void anon_vma_ctor(void *data, struct kmem_cache *cachep, unsigned long flags) { if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) { struct anon_vma *anon_vma = data; spin_lock_init(&anon_vma->lock); INIT_LIST_HEAD(&anon_vma->head); } } void __init anon_vma_init(void) { anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma), 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL); } /* * Getting a lock on a stable anon_vma from a page off the LRU is * tricky: page_lock_anon_vma rely on RCU to guard against the races. */ static struct anon_vma *page_lock_anon_vma(struct page *page) { struct anon_vma *anon_vma = NULL; unsigned long anon_mapping; rcu_read_lock(); anon_mapping = (unsigned long) page->mapping; if (!(anon_mapping & PAGE_MAPPING_ANON)) goto out; if (!page_mapped(page)) goto out; anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); out: rcu_read_unlock(); return anon_vma; } #ifdef CONFIG_MIGRATION /* * Remove an anonymous page from swap replacing the swap pte's * through real pte's pointing to valid pages and then releasing * the page from the swap cache. * * Must hold page lock on page and mmap_sem of one vma that contains * the page. */ void remove_from_swap(struct page *page) { struct anon_vma *anon_vma; struct vm_area_struct *vma; unsigned long mapping; if (!PageSwapCache(page)) return; mapping = (unsigned long)page->mapping; if (!mapping || (mapping & PAGE_MAPPING_ANON) == 0) return; /* * We hold the mmap_sem lock. So no need to call page_lock_anon_vma. */ anon_vma = (struct anon_vma *) (mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) remove_vma_swap(vma, page); spin_unlock(&anon_vma->lock); delete_from_swap_cache(page); } EXPORT_SYMBOL(remove_from_swap); #endif /* * At what user virtual address is page expected in vma? */ static inline unsigned long vma_address(struct page *page, struct vm_area_struct *vma) { pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); unsigned long address; address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT); if (unlikely(address < vma->vm_start || address >= vma->vm_end)) { /* page should be within any vma from prio_tree_next */ BUG_ON(!PageAnon(page)); return -EFAULT; } return address; } /* * At what user virtual address is page expected in vma? checking that the * page matches the vma: currently only used on anon pages, by unuse_vma; */ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) { if (PageAnon(page)) { if ((void *)vma->anon_vma != (void *)page->mapping - PAGE_MAPPING_ANON) return -EFAULT; } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { if (!vma->vm_file || vma->vm_file->f_mapping != page->mapping) return -EFAULT; } else return -EFAULT; return vma_address(page, vma); } /* * Check that @page is mapped at @address into @mm. * * On success returns with pte mapped and locked. */ pte_t *page_check_address(struct page *page, struct mm_struct *mm, unsigned long address, spinlock_t **ptlp) { pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *pte; spinlock_t *ptl; pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) return NULL; pud = pud_offset(pgd, address); if (!pud_present(*pud)) return NULL; pmd = pmd_offset(pud, address); if (!pmd_present(*pmd)) return NULL; pte = pte_offset_map(pmd, address); /* Make a quick check before getting the lock */ if (!pte_present(*pte)) { pte_unmap(pte); return NULL; } ptl = pte_lockptr(mm, pmd); spin_lock(ptl); if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) { *ptlp = ptl; return pte; } pte_unmap_unlock(pte, ptl); return NULL; } /* * Subfunctions of page_referenced: page_referenced_one called * repeatedly from either page_referenced_anon or page_referenced_file. */ static int page_referenced_one(struct page *page, struct vm_area_struct *vma, unsigned int *mapcount) { struct mm_struct *mm = vma->vm_mm; unsigned long address; pte_t *pte; spinlock_t *ptl; int referenced = 0; address = vma_address(page, vma); if (address == -EFAULT) goto out; pte = page_check_address(page, mm, address, &ptl); if (!pte) goto out; if (ptep_clear_flush_young(vma, address, pte)) referenced++; /* Pretend the page is referenced if the task has the swap token and is in the middle of a page fault. */ if (mm != current->mm && has_swap_token(mm) && rwsem_is_locked(&mm->mmap_sem)) referenced++; (*mapcount)--; pte_unmap_unlock(pte, ptl); out: return referenced; } static int page_referenced_anon(struct page *page) { unsigned int mapcount; struct anon_vma *anon_vma; struct vm_area_struct *vma; int referenced = 0; anon_vma = page_lock_anon_vma(page); if (!anon_vma) return referenced; mapcount = page_mapcount(page); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { referenced += page_referenced_one(page, vma, &mapcount); if (!mapcount) break; } spin_unlock(&anon_vma->lock); return referenced; } /** * page_referenced_file - referenced check for object-based rmap * @page: the page we're checking references on. * * For an object-based mapped page, find all the places it is mapped and * check/clear the referenced flag. This is done by following the page->mapping * pointer, then walking the chain of vmas it holds. It returns the number * of references it found. * * This function is only called from page_referenced for object-based pages. */ static int page_referenced_file(struct page *page) { unsigned int mapcount; struct address_space *mapping = page->mapping; pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); struct vm_area_struct *vma; struct prio_tree_iter iter; int referenced = 0; /* * The caller's checks on page->mapping and !PageAnon have made * sure that this is a file page: the check for page->mapping * excludes the case just before it gets set on an anon page. */ BUG_ON(PageAnon(page)); /* * The page lock not only makes sure that page->mapping cannot * suddenly be NULLified by truncation, it makes sure that the * structure at mapping cannot be freed and reused yet, * so we can safely take mapping->i_mmap_lock. */ BUG_ON(!PageLocked(page)); spin_lock(&mapping->i_mmap_lock); /* * i_mmap_lock does not stabilize mapcount at all, but mapcount * is more likely to be accurate if we note it after spinning. */ mapcount = page_mapcount(page); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) == (VM_LOCKED|VM_MAYSHARE)) { referenced++; break; } referenced += page_referenced_one(page, vma, &mapcount); if (!mapcount) break; } spin_unlock(&mapping->i_mmap_lock); return referenced; } /** * page_referenced - test if the page was referenced * @page: the page to test * @is_locked: caller holds lock on the page * * Quick test_and_clear_referenced for all mappings to a page, * returns the number of ptes which referenced the page. */ int page_referenced(struct page *page, int is_locked) { int referenced = 0; if (page_test_and_clear_young(page)) referenced++; if (TestClearPageReferenced(page)) referenced++; if (page_mapped(page) && page->mapping) { if (PageAnon(page)) referenced += page_referenced_anon(page); else if (is_locked) referenced += page_referenced_file(page); else if (TestSetPageLocked(page)) referenced++; else { if (page->mapping) referenced += page_referenced_file(page); unlock_page(page); } } return referenced; } /** * page_set_anon_rmap - setup new anonymous rmap * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped */ static void __page_set_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { struct anon_vma *anon_vma = vma->anon_vma; BUG_ON(!anon_vma); anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; page->mapping = (struct address_space *) anon_vma; page->index = linear_page_index(vma, address); /* * nr_mapped state can be updated without turning off * interrupts because it is not modified via interrupt. */ __inc_page_state(nr_mapped); } /** * page_add_anon_rmap - add pte mapping to an anonymous page