X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Frmap.c;h=720fc03a7bc454de75fa86f542770ab9b9660788;hb=62eede62dafb4a6633eae7ffbeb34c60dba5e7b1;hp=40158b59729ec3f6dac4390ecd5a57db7c719b52;hpb=f3dbd34460ff54962d3e3244b6bcb7f5295356e6;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/rmap.c b/mm/rmap.c index 40158b5..720fc03 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -14,34 +14,28 @@ * Original design by Rik van Riel 2001 * File methods by Dave McCracken 2003, 2004 * Anonymous methods by Andrea Arcangeli 2004 - * Contributions by Hugh Dickins 2003, 2004 + * Contributions by Hugh Dickins 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) + * inode->i_alloc_sem (vmtruncate_range) + * 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 @@ -53,30 +47,53 @@ #include #include #include +#include +#include +#include #include -struct kmem_cache *anon_vma_cachep; +#include "internal.h" -static inline void validate_anon_vma(struct vm_area_struct *find_vma) +static struct kmem_cache *anon_vma_cachep; + +static inline struct anon_vma *anon_vma_alloc(void) { -#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; + return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); +} - 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 +static inline void anon_vma_free(struct anon_vma *anon_vma) +{ + kmem_cache_free(anon_vma_cachep, anon_vma); } -/* This must be called under the mmap_sem. */ +/** + * anon_vma_prepare - attach an anon_vma to a memory region + * @vma: the memory region in question + * + * This makes sure the memory mapping described by 'vma' has + * an 'anon_vma' attached to it, so that we can associate the + * anonymous pages mapped into it with that anon_vma. + * + * The common case will be that we already have one, but if + * if not we either need to find an adjacent mapping that we + * can re-use the anon_vma from (very common when the only + * reason for splitting a vma has been mprotect()), or we + * allocate a new one. + * + * Anon-vma allocations are very subtle, because we may have + * optimistically looked up an anon_vma in page_lock_anon_vma() + * and that may actually touch the spinlock even in the newly + * allocated vma (it depends on RCU to make sure that the + * anon_vma isn't actually destroyed). + * + * As a result, we need to do proper anon_vma locking even + * for the new allocation. At the same time, we do not want + * to do any locking for the common case of already having + * an anon_vma. + * + * This must be called with the mmap_sem held for reading. + */ int anon_vma_prepare(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; @@ -84,20 +101,17 @@ int anon_vma_prepare(struct vm_area_struct *vma) might_sleep(); if (unlikely(!anon_vma)) { struct mm_struct *mm = vma->vm_mm; - struct anon_vma *allocated, *locked; + struct anon_vma *allocated; anon_vma = find_mergeable_anon_vma(vma); - if (anon_vma) { - allocated = NULL; - locked = anon_vma; - spin_lock(&locked->lock); - } else { + allocated = NULL; + if (!anon_vma) { anon_vma = anon_vma_alloc(); if (unlikely(!anon_vma)) return -ENOMEM; allocated = anon_vma; - locked = NULL; } + spin_lock(&anon_vma->lock); /* page_table_lock to protect against threads */ spin_lock(&mm->page_table_lock); @@ -108,8 +122,7 @@ int anon_vma_prepare(struct vm_area_struct *vma) } spin_unlock(&mm->page_table_lock); - if (locked) - spin_unlock(&locked->lock); + spin_unlock(&anon_vma->lock); if (unlikely(allocated)) anon_vma_free(allocated); } @@ -126,10 +139,8 @@ void __anon_vma_link(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; - if (anon_vma) { + if (anon_vma) list_add_tail(&vma->anon_vma_node, &anon_vma->head); - validate_anon_vma(vma); - } } void anon_vma_link(struct vm_area_struct *vma) @@ -139,7 +150,6 @@ void anon_vma_link(struct vm_area_struct *vma) if (anon_vma) { spin_lock(&anon_vma->lock); list_add_tail(&vma->anon_vma_node, &anon_vma->head); - validate_anon_vma(vma); spin_unlock(&anon_vma->lock); } } @@ -153,7 +163,6 @@ void anon_vma_unlink(struct vm_area_struct *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 */ @@ -164,22 +173,18 @@ void anon_vma_unlink(struct vm_area_struct *vma) anon_vma_free(anon_vma); } -static void anon_vma_ctor(void *data, struct kmem_cache *cachep, - unsigned long flags) +static void anon_vma_ctor(void *data) { - if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == - SLAB_CTOR_CONSTRUCTOR) { - struct anon_vma *anon_vma = data; + struct anon_vma *anon_vma = data; - spin_lock_init(&anon_vma->lock); - INIT_LIST_HEAD(&anon_vma->head); - } + 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); + 0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor); } /* @@ -188,7 +193,7 @@ void __init anon_vma_init(void) */ static struct anon_vma *page_lock_anon_vma(struct page *page) { - struct anon_vma *anon_vma = NULL; + struct anon_vma *anon_vma; unsigned long anon_mapping; rcu_read_lock(); @@ -200,13 +205,22 @@ static struct anon_vma *page_lock_anon_vma(struct page *page) anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON); spin_lock(&anon_vma->lock); + return anon_vma; out: rcu_read_unlock(); - return anon_vma; + return NULL; +} + +static void page_unlock_anon_vma(struct anon_vma *anon_vma) +{ + spin_unlock(&anon_vma->lock); + rcu_read_unlock(); } /* - * At what user virtual address is page expected in vma? + * At what user virtual address is page expected in @vma? + * Returns virtual address or -EFAULT if page's index/offset is not + * within the range mapped the @vma. */ static inline unsigned long vma_address(struct page *page, struct vm_area_struct *vma) @@ -216,8 +230,7 @@ vma_address(struct page *page, struct vm_area_struct *vma) 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)); + /* page should be within @vma mapping range */ return -EFAULT; } return address; @@ -245,10 +258,14 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) /* * Check that @page is mapped at @address into @mm. * + * If @sync is false, page_check_address may perform a racy check to avoid + * the page table lock when the pte is not present (helpful when reclaiming + * highly shared pages). + * * 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) + unsigned long address, spinlock_t **ptlp, int sync) { pgd_t *pgd; pud_t *pud; @@ -270,7 +287,7 @@ pte_t *page_check_address(struct page *page, struct mm_struct *mm, pte = pte_offset_map(pmd, address); /* Make a quick check before getting the lock */ - if (!pte_present(*pte)) { + if (!sync && !pte_present(*pte)) { pte_unmap(pte); return NULL; } @@ -285,12 +302,40 @@ pte_t *page_check_address(struct page *page, struct mm_struct *mm, return NULL; } +/** + * page_mapped_in_vma - check whether a page is really mapped in a VMA + * @page: the page to test + * @vma: the VMA to test + * + * Returns 1 if the page is mapped into the page tables of the VMA, 0 + * if the page is not mapped into the page tables of this VMA. Only + * valid for normal file or anonymous VMAs. + */ +static int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) +{ + unsigned long address; + pte_t *pte; + spinlock_t *ptl; + + address = vma_address(page, vma); + if (address == -EFAULT) /* out of vma range */ + return 0; + pte = page_check_address(page, vma->vm_mm, address, &ptl, 1); + if (!pte) /* the page is not in this mm */ + return 0; + pte_unmap_unlock(pte, ptl); + + return 1; +} + /* * 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 vm_area_struct *vma, + unsigned int *mapcount, + unsigned long *vm_flags) { struct mm_struct *mm = vma->vm_mm; unsigned long address; @@ -302,12 +347,32 @@ static int page_referenced_one(struct page *page, if (address == -EFAULT) goto out; - pte = page_check_address(page, mm, address, &ptl); + pte = page_check_address(page, mm, address, &ptl, 0); if (!pte) goto out; - if (ptep_clear_flush_young(vma, address, pte)) - referenced++; + /* + * Don't want to elevate referenced for mlocked page that gets this far, + * in order that it progresses to try_to_unmap and is moved to the + * unevictable list. + */ + if (vma->vm_flags & VM_LOCKED) { + *mapcount = 1; /* break early from loop */ + *vm_flags |= VM_LOCKED; + goto out_unmap; + } + + if (ptep_clear_flush_young_notify(vma, address, pte)) { + /* + * Don't treat a reference through a sequentially read + * mapping as such. If the page has been used in + * another mapping, we will catch it; if this other + * mapping is already gone, the unmap path will have + * set PG_referenced or activated the page. + */ + if (likely(!VM_SequentialReadHint(vma))) + referenced++; + } /* Pretend the page is referenced if the task has the swap token and is in the middle of a page fault. */ @@ -315,13 +380,18 @@ static int page_referenced_one(struct page *page, rwsem_is_locked(&mm->mmap_sem)) referenced++; +out_unmap: (*mapcount)--; pte_unmap_unlock(pte, ptl); out: + if (referenced) + *vm_flags |= vma->vm_flags; return referenced; } -static int page_referenced_anon(struct page *page) +static int page_referenced_anon(struct page *page, + struct mem_cgroup *mem_cont, + unsigned long *vm_flags) { unsigned int mapcount; struct anon_vma *anon_vma; @@ -334,17 +404,28 @@ static int page_referenced_anon(struct page *page) mapcount = page_mapcount(page); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { - referenced += page_referenced_one(page, vma, &mapcount); + /* + * If we are reclaiming on behalf of a cgroup, skip + * counting on behalf of references from different + * cgroups + */ + if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) + continue; + referenced += page_referenced_one(page, vma, + &mapcount, vm_flags); if (!mapcount) break; } - spin_unlock(&anon_vma->lock); + + page_unlock_anon_vma(anon_vma); return referenced; } /** * page_referenced_file - referenced check for object-based rmap * @page: the page we're checking references on. + * @mem_cont: target memory controller + * @vm_flags: collect encountered vma->vm_flags who actually referenced the page * * 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 @@ -353,7 +434,9 @@ static int page_referenced_anon(struct page *page) * * This function is only called from page_referenced for object-based pages. */ -static int page_referenced_file(struct page *page) +static int page_referenced_file(struct page *page, + struct mem_cgroup *mem_cont, + unsigned long *vm_flags) { unsigned int mapcount; struct address_space *mapping = page->mapping; @@ -386,12 +469,15 @@ static int page_referenced_file(struct page *page) 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 we are reclaiming on behalf of a cgroup, skip + * counting on behalf of references from different + * cgroups + */ + if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) + continue; + referenced += page_referenced_one(page, vma, + &mapcount, vm_flags); if (!mapcount) break; } @@ -404,38 +490,119 @@ static int page_referenced_file(struct page *page) * page_referenced - test if the page was referenced * @page: the page to test * @is_locked: caller holds lock on the page + * @mem_cont: target memory controller + * @vm_flags: collect encountered vma->vm_flags who actually referenced 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 page_referenced(struct page *page, + int is_locked, + struct mem_cgroup *mem_cont, + unsigned long *vm_flags) { int referenced = 0; - if (page_test_and_clear_young(page)) - referenced++; - if (TestClearPageReferenced(page)) referenced++; + *vm_flags = 0; if (page_mapped(page) && page->mapping) { if (PageAnon(page)) - referenced += page_referenced_anon(page); + referenced += page_referenced_anon(page, mem_cont, + vm_flags); else if (is_locked) - referenced += page_referenced_file(page); - else if (TestSetPageLocked(page)) + referenced += page_referenced_file(page, mem_cont, + vm_flags); + else if (!trylock_page(page)) referenced++; else { if (page->mapping) - referenced += page_referenced_file(page); + referenced += page_referenced_file(page, + mem_cont, vm_flags); unlock_page(page); } } + + if (page_test_and_clear_young(page)) + referenced++; + return referenced; } +static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) +{ + struct mm_struct *mm = vma->vm_mm; + unsigned long address; + pte_t *pte; + spinlock_t *ptl; + int ret = 0; + + address = vma_address(page, vma); + if (address == -EFAULT) + goto out; + + pte = page_check_address(page, mm, address, &ptl, 1); + if (!pte) + goto out; + + if (pte_dirty(*pte) || pte_write(*pte)) { + pte_t entry; + + flush_cache_page(vma, address, pte_pfn(*pte)); + entry = ptep_clear_flush_notify(vma, address, pte); + entry = pte_wrprotect(entry); + entry = pte_mkclean(entry); + set_pte_at(mm, address, pte, entry); + ret = 1; + } + + pte_unmap_unlock(pte, ptl); +out: + return ret; +} + +static int page_mkclean_file(struct address_space *mapping, struct page *page) +{ + pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); + struct vm_area_struct *vma; + struct prio_tree_iter iter; + int ret = 0; + + BUG_ON(PageAnon(page)); + + spin_lock(&mapping->i_mmap_lock); + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + if (vma->vm_flags & VM_SHARED) + ret += page_mkclean_one(page, vma); + } + spin_unlock(&mapping->i_mmap_lock); + return ret; +} + +int page_mkclean(struct page *page) +{ + int ret = 0; + + BUG_ON(!PageLocked(page)); + + if (page_mapped(page)) { + struct address_space *mapping = page_mapping(page); + if (mapping) { + ret = page_mkclean_file(mapping, page); + if (page_test_dirty(page)) { + page_clear_dirty(page); + ret = 1; + } + } + } + + return ret; +} +EXPORT_SYMBOL_GPL(page_mkclean); + /** - * page_set_anon_rmap - setup new anonymous rmap + * __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 @@ -459,22 +626,54 @@ static void __page_set_anon_rmap(struct page *page, } /** + * __page_check_anon_rmap - sanity check anonymous rmap addition + * @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_check_anon_rmap(struct page *page, + struct vm_area_struct *vma, unsigned long address) +{ +#ifdef CONFIG_DEBUG_VM + /* + * The page's anon-rmap details (mapping and index) are guaranteed to + * be set up correctly at this point. + * + * We have exclusion against page_add_anon_rmap because the caller + * always holds the page locked, except if called from page_dup_rmap, + * in which case the page is already known to be setup. + * + * We have exclusion against page_add_new_anon_rmap because those pages + * are initially only visible via the pagetables, and the pte is locked + * over the call to page_add_new_anon_rmap. + */ + struct anon_vma *anon_vma = vma->anon_vma; + anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; + BUG_ON(page->mapping != (struct address_space *)anon_vma); + BUG_ON(page->index != linear_page_index(vma, address)); +#endif +} + +/** * page_add_anon_rmap - add pte mapping to an anonymous page * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped * - * The caller needs to hold the pte lock. + * The caller needs to hold the pte lock and the page must be locked. */ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { + VM_BUG_ON(!PageLocked(page)); + VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); if (atomic_inc_and_test(&page->_mapcount)) __page_set_anon_rmap(page, vma, address); - /* else checking page index and mapping is racy */ + else + __page_check_anon_rmap(page, vma, address); } -/* +/** * page_add_new_anon_rmap - add pte mapping to a new anonymous page * @page: the page to add the mapping to * @vma: the vm area in which the mapping is added @@ -482,12 +681,19 @@ void page_add_anon_rmap(struct page *page, * * Same as page_add_anon_rmap but must only be called on *new* pages. * This means the inc-and-test can be bypassed. + * Page does not have to be locked. */ void page_add_new_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { - atomic_set(&page->_mapcount, 0); /* elevate count by 1 (starts at -1) */ + VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); + SetPageSwapBacked(page); + atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */ __page_set_anon_rmap(page, vma, address); + if (page_evictable(page, vma)) + lru_cache_add_lru(page, LRU_ACTIVE_ANON); + else + add_page_to_unevictable_list(page); } /** @@ -498,8 +704,10 @@ void page_add_new_anon_rmap(struct page *page, */ void page_add_file_rmap(struct page *page) { - if (atomic_inc_and_test(&page->_mapcount)) + if (atomic_inc_and_test(&page->_mapcount)) { __inc_zone_page_state(page, NR_FILE_MAPPED); + mem_cgroup_update_mapped_file_stat(page, 1); + } } /** @@ -510,30 +718,37 @@ void page_add_file_rmap(struct page *page) */ void page_remove_rmap(struct page *page) { - if (atomic_add_negative(-1, &page->_mapcount)) { -#ifdef CONFIG_DEBUG_VM - if (unlikely(page_mapcount(page) < 0)) { - printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); - printk (KERN_EMERG " page->flags = %lx\n", page->flags); - printk (KERN_EMERG " page->count = %x\n", page_count(page)); - printk (KERN_EMERG " page->mapping = %p\n", page->mapping); - } -#endif - BUG_ON(page_mapcount(page) < 0); - /* - * It would be tidy to reset the PageAnon mapping here, - * but that might overwrite a racing page_add_anon_rmap - * which increments mapcount after us but sets mapping - * before us: so leave the reset to free_hot_cold_page, - * and remember that it's only reliable while mapped. - * Leaving it set also helps swapoff to reinstate ptes - * faster for those pages still in swapcache. - */ - if (page_test_and_clear_dirty(page)) - set_page_dirty(page); - __dec_zone_page_state(page, - PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); + /* page still mapped by someone else? */ + if (!atomic_add_negative(-1, &page->_mapcount)) + return; + + /* + * Now that the last pte has gone, s390 must transfer dirty + * flag from storage key to struct page. We can usually skip + * this if the page is anon, so about to be freed; but perhaps + * not if it's in swapcache - there might be another pte slot + * containing the swap entry, but page not yet written to swap. + */ + if ((!PageAnon(page) || PageSwapCache(page)) && page_test_dirty(page)) { + page_clear_dirty(page); + set_page_dirty(page); + } + if (PageAnon(page)) { + mem_cgroup_uncharge_page(page); + __dec_zone_page_state(page, NR_ANON_PAGES); + } else { + __dec_zone_page_state(page, NR_FILE_MAPPED); } + mem_cgroup_update_mapped_file_stat(page, -1); + /* + * It would be tidy to reset the PageAnon mapping here, + * but that might overwrite a racing page_add_anon_rmap + * which increments mapcount after us but sets mapping + * before us: so leave the reset to free_hot_cold_page, + * and remember that it's only reliable while mapped. + * Leaving it set also helps swapoff to reinstate ptes + * faster for those pages still in swapcache. + */ } /* @@ -554,7 +769,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, if (address == -EFAULT) goto out; - pte = page_check_address(page, mm, address, &ptl); + pte = page_check_address(page, mm, address, &ptl, 0); if (!pte) goto out; @@ -563,15 +778,20 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * If it's recently referenced (perhaps page_referenced * skipped over this mm) then we should reactivate it. */ - if (!migration && ((vma->vm_flags & VM_LOCKED) || - (ptep_clear_flush_young(vma, address, pte)))) { - ret = SWAP_FAIL; - goto out_unmap; - } + if (!migration) { + if (vma->vm_flags & VM_LOCKED) { + ret = SWAP_MLOCK; + goto out_unmap; + } + if (ptep_clear_flush_young_notify(vma, address, pte)) { + ret = SWAP_FAIL; + goto out_unmap; + } + } /* Nuke the page table entry. */ flush_cache_page(vma, address, page_to_pfn(page)); - pteval = ptep_clear_flush(vma, address, pte); + pteval = ptep_clear_flush_notify(vma, address, pte); /* Move the dirty bit to the physical page now the pte is gone. */ if (pte_dirty(pteval)) @@ -596,8 +816,7 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, spin_unlock(&mmlist_lock); } dec_mm_counter(mm, anon_rss); -#ifdef CONFIG_MIGRATION - } else { + } else if (PAGE_MIGRATION) { /* * Store the pfn of the page in a special migration * pte. do_swap_page() will wait until the migration @@ -605,19 +824,15 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, */ BUG_ON(!migration); entry = make_migration_entry(page, pte_write(pteval)); -#endif } set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); BUG_ON(pte_file(*pte)); - } else -#ifdef CONFIG_MIGRATION - if (migration) { + } else if (PAGE_MIGRATION && migration) { /* Establish migration entry for a file page */ swp_entry_t entry; entry = make_migration_entry(page, pte_write(pteval)); set_pte_at(mm, address, pte, swp_entry_to_pte(entry)); } else -#endif dec_mm_counter(mm, file_rss); @@ -648,12 +863,17 @@ out: * For very sparsely populated VMAs this is a little inefficient - chances are * there there won't be many ptes located within the scan cluster. In this case * maybe we could scan further - to the end of the pte page, perhaps. + * + * Mlocked pages: check VM_LOCKED under mmap_sem held for read, if we can + * acquire it without blocking. If vma locked, mlock the pages in the cluster, + * rather than unmapping them. If we encounter the "check_page" that vmscan is + * trying to unmap, return SWAP_MLOCK, else default SWAP_AGAIN. */ #define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE) #define CLUSTER_MASK (~(CLUSTER_SIZE - 1)) -static void try_to_unmap_cluster(unsigned long cursor, - unsigned int *mapcount, struct vm_area_struct *vma) +static int try_to_unmap_cluster(unsigned long cursor, unsigned int *mapcount, + struct vm_area_struct *vma, struct page *check_page) { struct mm_struct *mm = vma->vm_mm; pgd_t *pgd; @@ -665,6 +885,8 @@ static void try_to_unmap_cluster(unsigned long cursor, struct page *page; unsigned long address; unsigned long end; + int ret = SWAP_AGAIN; + int locked_vma = 0; address = (vma->vm_start + cursor) & CLUSTER_MASK; end = address + CLUSTER_SIZE; @@ -675,15 +897,26 @@ static void try_to_unmap_cluster(unsigned long cursor, pgd = pgd_offset(mm, address); if (!pgd_present(*pgd)) - return; + return ret; pud = pud_offset(pgd, address); if (!pud_present(*pud)) - return; + return ret; pmd = pmd_offset(pud, address); if (!pmd_present(*pmd)) - return; + return ret; + + /* + * MLOCK_PAGES => feature is configured. + * if we can acquire the mmap_sem for read, and vma is VM_LOCKED, + * keep the sem while scanning the cluster for mlocking pages. + */ + if (MLOCK_PAGES && down_read_trylock(&vma->vm_mm->mmap_sem)) { + locked_vma = (vma->vm_flags & VM_LOCKED); + if (!locked_vma) + up_read(&vma->vm_mm->mmap_sem); /* don't need it */ + } pte = pte_offset_map_lock(mm, pmd, address, &ptl); @@ -696,12 +929,19 @@ static void try_to_unmap_cluster(unsigned long cursor, page = vm_normal_page(vma, address, *pte); BUG_ON(!page || PageAnon(page)); - if (ptep_clear_flush_young(vma, address, pte)) + if (locked_vma) { + mlock_vma_page(page); /* no-op if already mlocked */ + if (page == check_page) + ret = SWAP_MLOCK; + continue; /* don't unmap */ + } + + if (ptep_clear_flush_young_notify(vma, address, pte)) continue; /* Nuke the page table entry. */ flush_cache_page(vma, address, pte_pfn(*pte)); - pteval = ptep_clear_flush(vma, address, pte); + pteval = ptep_clear_flush_notify(vma, address, pte); /* If nonlinear, store the file page offset in the pte. */ if (page->index != linear_page_index(vma, address)) @@ -717,37 +957,104 @@ static void try_to_unmap_cluster(unsigned long cursor, (*mapcount)--; } pte_unmap_unlock(pte - 1, ptl); + if (locked_vma) + up_read(&vma->vm_mm->mmap_sem); + return ret; +} + +/* + * common handling for pages mapped in VM_LOCKED vmas + */ +static int try_to_mlock_page(struct page *page, struct vm_area_struct *vma) +{ + int mlocked = 0; + + if (down_read_trylock(&vma->vm_mm->mmap_sem)) { + if (vma->vm_flags & VM_LOCKED) { + mlock_vma_page(page); + mlocked++; /* really mlocked the page */ + } + up_read(&vma->vm_mm->mmap_sem); + } + return mlocked; } -static int try_to_unmap_anon(struct page *page, int migration) +/** + * try_to_unmap_anon - unmap or unlock anonymous page using the object-based + * rmap method + * @page: the page to unmap/unlock + * @unlock: request for unlock rather than unmap [unlikely] + * @migration: unmapping for migration - ignored if @unlock + * + * Find all the mappings of a page using the mapping pointer and the vma chains + * contained in the anon_vma struct it points to. + * + * This function is only called from try_to_unmap/try_to_munlock for + * anonymous pages. + * When called from try_to_munlock(), the mmap_sem of the mm containing the vma + * where the page was found will be held for write. So, we won't recheck + * vm_flags for that VMA. That should be OK, because that vma shouldn't be + * 'LOCKED. + */ +static int try_to_unmap_anon(struct page *page, int unlock, int migration) { struct anon_vma *anon_vma; struct vm_area_struct *vma; + unsigned int mlocked = 0; int ret = SWAP_AGAIN; + if (MLOCK_PAGES && unlikely(unlock)) + ret = SWAP_SUCCESS; /* default for try_to_munlock() */ + anon_vma = page_lock_anon_vma(page); if (!anon_vma) return ret; list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { - ret = try_to_unmap_one(page, vma, migration); - if (ret == SWAP_FAIL || !page_mapped(page)) - break; + if (MLOCK_PAGES && unlikely(unlock)) { + if (!((vma->vm_flags & VM_LOCKED) && + page_mapped_in_vma(page, vma))) + continue; /* must visit all unlocked vmas */ + ret = SWAP_MLOCK; /* saw at least one mlocked vma */ + } else { + ret = try_to_unmap_one(page, vma, migration); + if (ret == SWAP_FAIL || !page_mapped(page)) + break; + } + if (ret == SWAP_MLOCK) { + mlocked = try_to_mlock_page(page, vma); + if (mlocked) + break; /* stop if actually mlocked page */ + } } - spin_unlock(&anon_vma->lock); + + page_unlock_anon_vma(anon_vma); + + if (mlocked) + ret = SWAP_MLOCK; /* actually mlocked the page */ + else if (ret == SWAP_MLOCK) + ret = SWAP_AGAIN; /* saw VM_LOCKED vma */ + return ret; } /** - * try_to_unmap_file - unmap file page using the object-based rmap method - * @page: the page to unmap + * try_to_unmap_file - unmap/unlock file page using the object-based rmap method + * @page: the page to unmap/unlock + * @unlock: request for unlock rather than unmap [unlikely] + * @migration: unmapping for migration - ignored if @unlock * * Find all the mappings of a page using the mapping pointer and the vma chains * contained in the address_space struct it points to. * - * This function is only called from try_to_unmap for object-based pages. + * This function is only called from try_to_unmap/try_to_munlock for + * object-based pages. + * When called from try_to_munlock(), the mmap_sem of the mm containing the vma + * where the page was found will be held for write. So, we won't recheck + * vm_flags for that VMA. That should be OK, because that vma shouldn't be + * 'LOCKED. */ -static int try_to_unmap_file(struct page *page, int migration) +static int try_to_unmap_file(struct page *page, int unlock, int migration) { struct address_space *mapping = page->mapping; pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); @@ -758,20 +1065,45 @@ static int try_to_unmap_file(struct page *page, int migration) unsigned long max_nl_cursor = 0; unsigned long max_nl_size = 0; unsigned int mapcount; + unsigned int mlocked = 0; + + if (MLOCK_PAGES && unlikely(unlock)) + ret = SWAP_SUCCESS; /* default for try_to_munlock() */ spin_lock(&mapping->i_mmap_lock); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { - ret = try_to_unmap_one(page, vma, migration); - if (ret == SWAP_FAIL || !page_mapped(page)) - goto out; + if (MLOCK_PAGES && unlikely(unlock)) { + if (!((vma->vm_flags & VM_LOCKED) && + page_mapped_in_vma(page, vma))) + continue; /* must visit all vmas */ + ret = SWAP_MLOCK; + } else { + ret = try_to_unmap_one(page, vma, migration); + if (ret == SWAP_FAIL || !page_mapped(page)) + goto out; + } + if (ret == SWAP_MLOCK) { + mlocked = try_to_mlock_page(page, vma); + if (mlocked) + break; /* stop if actually mlocked page */ + } } + if (mlocked) + goto out; + if (list_empty(&mapping->i_mmap_nonlinear)) goto out; list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) { - if ((vma->vm_flags & VM_LOCKED) && !migration) + if (MLOCK_PAGES && unlikely(unlock)) { + if (!(vma->vm_flags & VM_LOCKED)) + continue; /* must visit all vmas */ + ret = SWAP_MLOCK; /* leave mlocked == 0 */ + goto out; /* no need to look further */ + } + if (!MLOCK_PAGES && !migration && (vma->vm_flags & VM_LOCKED)) continue; cursor = (unsigned long) vma->vm_private_data; if (cursor > max_nl_cursor) @@ -781,7 +1113,7 @@ static int try_to_unmap_file(struct page *page, int migration) max_nl_size = cursor; } - if (max_nl_size == 0) { /* any nonlinears locked or reserved */ + if (max_nl_size == 0) { /* all nonlinears locked or reserved ? */ ret = SWAP_FAIL; goto out; } @@ -805,12 +1137,16 @@ static int try_to_unmap_file(struct page *page, int migration) do { list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) { - if ((vma->vm_flags & VM_LOCKED) && !migration) + if (!MLOCK_PAGES && !migration && + (vma->vm_flags & VM_LOCKED)) continue; cursor = (unsigned long) vma->vm_private_data; while ( cursor < max_nl_cursor && cursor < vma->vm_end - vma->vm_start) { - try_to_unmap_cluster(cursor, &mapcount, vma); + ret = try_to_unmap_cluster(cursor, &mapcount, + vma, page); + if (ret == SWAP_MLOCK) + mlocked = 2; /* to return below */ cursor += CLUSTER_SIZE; vma->vm_private_data = (void *) cursor; if ((int)mapcount <= 0) @@ -831,12 +1167,17 @@ static int try_to_unmap_file(struct page *page, int migration) vma->vm_private_data = NULL; out: spin_unlock(&mapping->i_mmap_lock); + if (mlocked) + ret = SWAP_MLOCK; /* actually mlocked the page */ + else if (ret == SWAP_MLOCK) + ret = SWAP_AGAIN; /* saw VM_LOCKED vma */ return ret; } /** * try_to_unmap - try to remove all page table mappings to a page * @page: the page to get unmapped + * @migration: migration flag * * Tries to remove all the page table entries which are mapping this * page, used in the pageout path. Caller must hold the page lock. @@ -845,6 +1186,7 @@ out: * SWAP_SUCCESS - we succeeded in removing all mappings * SWAP_AGAIN - we missed a mapping, try again later * SWAP_FAIL - the page is unswappable + * SWAP_MLOCK - page is mlocked. */ int try_to_unmap(struct page *page, int migration) { @@ -853,12 +1195,35 @@ int try_to_unmap(struct page *page, int migration) BUG_ON(!PageLocked(page)); if (PageAnon(page)) - ret = try_to_unmap_anon(page, migration); + ret = try_to_unmap_anon(page, 0, migration); else - ret = try_to_unmap_file(page, migration); - - if (!page_mapped(page)) + ret = try_to_unmap_file(page, 0, migration); + if (ret != SWAP_MLOCK && !page_mapped(page)) ret = SWAP_SUCCESS; return ret; } +/** + * try_to_munlock - try to munlock a page + * @page: the page to be munlocked + * + * Called from munlock code. Checks all of the VMAs mapping the page + * to make sure nobody else has this page mlocked. The page will be + * returned with PG_mlocked cleared if no other vmas have it mlocked. + * + * Return values are: + * + * SWAP_SUCCESS - no vma's holding page mlocked. + * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem + * SWAP_MLOCK - page is now mlocked. + */ +int try_to_munlock(struct page *page) +{ + VM_BUG_ON(!PageLocked(page) || PageLRU(page)); + + if (PageAnon(page)) + return try_to_unmap_anon(page, 1, 0); + else + return try_to_unmap_file(page, 1, 0); +} +