X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=mm%2Frmap.c;h=98135dbd25ba4c5ab29889dc6a9d5a23b7f0ff4f;hb=569b846df54ffb2827b83ce3244c5f032394cba4;hp=bf0a5b7cfb8e7a97369271ed235a714bd11dfd12;hpb=3c18ddd160d1fcd46d1131d9ad6c594dd8e9af99;p=safe%2Fjmp%2Flinux-2.6 diff --git a/mm/rmap.c b/mm/rmap.c index bf0a5b7..98135db 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -14,7 +14,7 @@ * 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 */ /* @@ -36,6 +36,11 @@ * mapping->tree_lock (widely used, in set_page_dirty, * in arch-dependent flush_dcache_mmap_lock, * within inode_lock in __sync_single_inode) + * + * (code doesn't rely on that order so it could be switched around) + * ->tasklist_lock + * anon_vma->lock (memory_failure, collect_procs_anon) + * pte map lock */ #include @@ -44,17 +49,57 @@ #include #include #include +#include #include #include #include -#include #include +#include +#include #include -struct kmem_cache *anon_vma_cachep; +#include "internal.h" + +static struct kmem_cache *anon_vma_cachep; + +static inline struct anon_vma *anon_vma_alloc(void) +{ + return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL); +} + +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; @@ -62,20 +107,17 @@ 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); @@ -86,8 +128,7 @@ 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); } @@ -131,18 +172,19 @@ void anon_vma_unlink(struct vm_area_struct *vma) list_del(&vma->anon_vma_node); /* We must garbage collect the anon_vma if it's empty */ - empty = list_empty(&anon_vma->head); + empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma); spin_unlock(&anon_vma->lock); if (empty) anon_vma_free(anon_vma); } -static void anon_vma_ctor(struct kmem_cache *cachep, void *data) +static void anon_vma_ctor(void *data) { struct anon_vma *anon_vma = data; spin_lock_init(&anon_vma->lock); + ksm_refcount_init(anon_vma); INIT_LIST_HEAD(&anon_vma->head); } @@ -156,14 +198,14 @@ void __init anon_vma_init(void) * 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 *page_lock_anon_vma(struct page *page) { struct anon_vma *anon_vma; unsigned long anon_mapping; rcu_read_lock(); - anon_mapping = (unsigned long) page->mapping; - if (!(anon_mapping & PAGE_MAPPING_ANON)) + anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping); + if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON) goto out; if (!page_mapped(page)) goto out; @@ -176,7 +218,7 @@ out: return NULL; } -static void page_unlock_anon_vma(struct anon_vma *anon_vma) +void page_unlock_anon_vma(struct anon_vma *anon_vma) { spin_unlock(&anon_vma->lock); rcu_read_unlock(); @@ -202,14 +244,13 @@ vma_address(struct page *page, struct vm_area_struct *vma) } /* - * 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; + * At what user virtual address is page expected in vma? + * checking that the page matches the 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) + if (vma->anon_vma != page_anon_vma(page)) return -EFAULT; } else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) { if (!vma->vm_file || @@ -223,10 +264,14 @@ 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; @@ -248,7 +293,7 @@ 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; } @@ -263,32 +308,71 @@ 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. + */ +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) +int page_referenced_one(struct page *page, struct vm_area_struct *vma, + unsigned long address, unsigned int *mapcount, + unsigned long *vm_flags) { 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); + pte = page_check_address(page, mm, address, &ptl, 0); if (!pte) goto out; + /* + * 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) { - referenced++; *mapcount = 1; /* break early from loop */ - } else if (ptep_clear_flush_young(vma, address, pte)) - referenced++; + *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. */ @@ -296,14 +380,19 @@ static int page_referenced_one(struct page *page, rwsem_is_locked(&mm->mmap_sem)) referenced++; +out_unmap: (*mapcount)--; pte_unmap_unlock(pte, ptl); + + if (referenced) + *vm_flags |= vma->vm_flags; out: return referenced; } static int page_referenced_anon(struct page *page, - struct mem_cgroup *mem_cont) + struct mem_cgroup *mem_cont, + unsigned long *vm_flags) { unsigned int mapcount; struct anon_vma *anon_vma; @@ -316,6 +405,9 @@ static int page_referenced_anon(struct page *page, mapcount = page_mapcount(page); list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; /* * If we are reclaiming on behalf of a cgroup, skip * counting on behalf of references from different @@ -323,7 +415,8 @@ static int page_referenced_anon(struct page *page, */ if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) continue; - referenced += page_referenced_one(page, vma, &mapcount); + referenced += page_referenced_one(page, vma, address, + &mapcount, vm_flags); if (!mapcount) break; } @@ -336,6 +429,7 @@ static int page_referenced_anon(struct page *page, * 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 @@ -345,7 +439,8 @@ 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, - struct mem_cgroup *mem_cont) + struct mem_cgroup *mem_cont, + unsigned long *vm_flags) { unsigned int mapcount; struct address_space *mapping = page->mapping; @@ -378,6 +473,9 @@ static int page_referenced_file(struct page *page, mapcount = page_mapcount(page); vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; /* * If we are reclaiming on behalf of a cgroup, skip * counting on behalf of references from different @@ -385,12 +483,8 @@ static int page_referenced_file(struct page *page, */ if (mem_cont && !mm_match_cgroup(vma->vm_mm, mem_cont)) continue; - if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE)) - == (VM_LOCKED|VM_MAYSHARE)) { - referenced++; - break; - } - referenced += page_referenced_one(page, vma, &mapcount); + referenced += page_referenced_one(page, vma, address, + &mapcount, vm_flags); if (!mapcount) break; } @@ -404,52 +498,59 @@ static int page_referenced_file(struct page *page, * @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, - struct mem_cgroup *mem_cont) +int page_referenced(struct page *page, + int is_locked, + struct mem_cgroup *mem_cont, + unsigned long *vm_flags) { int referenced = 0; + int we_locked = 0; if (TestClearPageReferenced(page)) referenced++; - if (page_mapped(page) && page->mapping) { - if (PageAnon(page)) - referenced += page_referenced_anon(page, mem_cont); - else if (is_locked) - referenced += page_referenced_file(page, mem_cont); - else if (TestSetPageLocked(page)) - referenced++; - else { - if (page->mapping) - referenced += - page_referenced_file(page, mem_cont); - unlock_page(page); + *vm_flags = 0; + if (page_mapped(page) && page_rmapping(page)) { + if (!is_locked && (!PageAnon(page) || PageKsm(page))) { + we_locked = trylock_page(page); + if (!we_locked) { + referenced++; + goto out; + } } + if (unlikely(PageKsm(page))) + referenced += page_referenced_ksm(page, mem_cont, + vm_flags); + else if (PageAnon(page)) + referenced += page_referenced_anon(page, mem_cont, + vm_flags); + else if (page->mapping) + referenced += page_referenced_file(page, mem_cont, + vm_flags); + if (we_locked) + unlock_page(page); } - +out: if (page_test_and_clear_young(page)) referenced++; return referenced; } -static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) +static int page_mkclean_one(struct page *page, struct vm_area_struct *vma, + unsigned long address) { 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); + pte = page_check_address(page, mm, address, &ptl, 1); if (!pte) goto out; @@ -457,7 +558,7 @@ static int page_mkclean_one(struct page *page, struct vm_area_struct *vma) pte_t entry; flush_cache_page(vma, address, pte_pfn(*pte)); - entry = ptep_clear_flush(vma, address, pte); + entry = ptep_clear_flush_notify(vma, address, pte); entry = pte_wrprotect(entry); entry = pte_mkclean(entry); set_pte_at(mm, address, pte, entry); @@ -480,8 +581,12 @@ static int page_mkclean_file(struct address_space *mapping, struct page *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); + if (vma->vm_flags & VM_SHARED) { + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; + ret += page_mkclean_one(page, vma, address); + } } spin_unlock(&mapping->i_mmap_lock); return ret; @@ -522,14 +627,7 @@ static void __page_set_anon_rmap(struct page *page, 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_zone_page_state(page, NR_ANON_PAGES); } /** @@ -567,23 +665,26 @@ static void __page_check_anon_rmap(struct page *page, * @vma: the vm area in which the mapping is added * @address: the user virtual address mapped * - * The caller needs to hold the pte lock and the page must be locked. + * The caller needs to hold the pte lock, and the page must be locked in + * the anon_vma case: to serialize mapping,index checking after setting, + * and to ensure that PageAnon is not being upgraded racily to PageKsm + * (but PageKsm is never downgraded to PageAnon). */ void page_add_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { + int first = atomic_inc_and_test(&page->_mapcount); + if (first) + __inc_zone_page_state(page, NR_ANON_PAGES); + if (unlikely(PageKsm(page))) + return; + VM_BUG_ON(!PageLocked(page)); VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end); - if (atomic_inc_and_test(&page->_mapcount)) + if (first) __page_set_anon_rmap(page, vma, address); - else { + else __page_check_anon_rmap(page, vma, address); - /* - * We unconditionally charged during prepare, we uncharge here - * This takes care of balancing the reference counts - */ - mem_cgroup_uncharge_page(page); - } } /** @@ -599,9 +700,15 @@ void page_add_anon_rmap(struct page *page, void page_add_new_anon_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) { - BUG_ON(address < vma->vm_start || address >= vma->vm_end); - 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) */ + __inc_zone_page_state(page, NR_ANON_PAGES); __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); } /** @@ -612,102 +719,67 @@ 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); - else - /* - * We unconditionally charged during prepare, we uncharge here - * This takes care of balancing the reference counts - */ - mem_cgroup_uncharge_page(page); -} - -#ifdef CONFIG_DEBUG_VM -/** - * page_dup_rmap - duplicate pte mapping to a page - * @page: the page to add the mapping to - * @vma: the vm area being duplicated - * @address: the user virtual address mapped - * - * For copy_page_range only: minimal extract from page_add_file_rmap / - * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's - * quicker. - * - * The caller needs to hold the pte lock. - */ -void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) -{ - BUG_ON(page_mapcount(page) == 0); - if (PageAnon(page)) - __page_check_anon_rmap(page, vma, address); - atomic_inc(&page->_mapcount); + mem_cgroup_update_mapped_file_stat(page, 1); + } } -#endif /** * page_remove_rmap - take down pte mapping from a page * @page: page to remove mapping from - * @vma: the vm area in which the mapping is removed * * The caller needs to hold the pte lock. */ -void page_remove_rmap(struct page *page, struct vm_area_struct *vma) -{ - if (atomic_add_negative(-1, &page->_mapcount)) { - if (unlikely(page_mapcount(page) < 0)) { - printk (KERN_EMERG "Eeek! page_mapcount(page) went negative! (%d)\n", page_mapcount(page)); - printk (KERN_EMERG " page pfn = %lx\n", page_to_pfn(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); - print_symbol (KERN_EMERG " vma->vm_ops = %s\n", (unsigned long)vma->vm_ops); - if (vma->vm_ops) { - print_symbol (KERN_EMERG " vma->vm_ops->fault = %s\n", (unsigned long)vma->vm_ops->fault); - } - if (vma->vm_file && vma->vm_file->f_op) - print_symbol (KERN_EMERG " vma->vm_file->f_op->mmap = %s\n", (unsigned long)vma->vm_file->f_op->mmap); - BUG(); - } +void page_remove_rmap(struct page *page) +{ + /* page still mapped by someone else? */ + if (!atomic_add_negative(-1, &page->_mapcount)) + return; - /* - * 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_dirty(page)) { - page_clear_dirty(page); - set_page_dirty(page); - } + /* + * 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, - PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); + __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. + */ } /* * Subfunctions of try_to_unmap: try_to_unmap_one called * repeatedly from either try_to_unmap_anon or try_to_unmap_file. */ -static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, - int migration) +int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, + unsigned long address, enum ttu_flags flags) { struct mm_struct *mm = vma->vm_mm; - unsigned long address; pte_t *pte; pte_t pteval; spinlock_t *ptl; int ret = SWAP_AGAIN; - address = vma_address(page, 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; @@ -716,15 +788,23 @@ 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 (!(flags & TTU_IGNORE_MLOCK)) { + if (vma->vm_flags & VM_LOCKED) + goto out_mlock; + + if (TTU_ACTION(flags) == TTU_MUNLOCK) + goto out_unmap; } + if (!(flags & TTU_IGNORE_ACCESS)) { + 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)) @@ -733,7 +813,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, /* Update high watermark before we lower rss */ update_hiwater_rss(mm); - if (PageAnon(page)) { + if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) { + if (PageAnon(page)) + dec_mm_counter(mm, anon_rss); + else + dec_mm_counter(mm, file_rss); + set_pte_at(mm, address, pte, + swp_entry_to_pte(make_hwpoison_entry(page))); + } else if (PageAnon(page)) { swp_entry_t entry = { .val = page_private(page) }; if (PageSwapCache(page)) { @@ -741,7 +828,11 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, * Store the swap location in the pte. * See handle_pte_fault() ... */ - swap_duplicate(entry); + if (swap_duplicate(entry) < 0) { + set_pte_at(mm, address, pte, pteval); + ret = SWAP_FAIL; + goto out_unmap; + } if (list_empty(&mm->mmlist)) { spin_lock(&mmlist_lock); if (list_empty(&mm->mmlist)) @@ -749,38 +840,53 @@ 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 * pte is removed and then restart fault handling. */ - BUG_ON(!migration); + BUG_ON(TTU_ACTION(flags) != TTU_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 && (TTU_ACTION(flags) == TTU_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); - - page_remove_rmap(page, vma); + page_remove_rmap(page); page_cache_release(page); out_unmap: pte_unmap_unlock(pte, ptl); out: return ret; + +out_mlock: + pte_unmap_unlock(pte, ptl); + + + /* + * We need mmap_sem locking, Otherwise VM_LOCKED check makes + * unstable result and race. Plus, We can't wait here because + * we now hold anon_vma->lock or mapping->i_mmap_lock. + * if trylock failed, the page remain in evictable lru and later + * vmscan could retry to move the page to unevictable lru if the + * page is actually mlocked. + */ + if (down_read_trylock(&vma->vm_mm->mmap_sem)) { + if (vma->vm_flags & VM_LOCKED) { + mlock_vma_page(page); + ret = SWAP_MLOCK; + } + up_read(&vma->vm_mm->mmap_sem); + } + return ret; } /* @@ -801,12 +907,17 @@ 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; @@ -818,6 +929,8 @@ 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; @@ -828,15 +941,25 @@ 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; + + /* + * 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 (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); @@ -849,12 +972,19 @@ 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)) @@ -864,15 +994,34 @@ static void try_to_unmap_cluster(unsigned long cursor, if (pte_dirty(pteval)) set_page_dirty(page); - page_remove_rmap(page, vma); + page_remove_rmap(page); page_cache_release(page); dec_mm_counter(mm, file_rss); (*mapcount)--; } pte_unmap_unlock(pte - 1, ptl); + if (locked_vma) + up_read(&vma->vm_mm->mmap_sem); + return ret; } -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 + * @flags: action and flags + * + * 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, enum ttu_flags flags) { struct anon_vma *anon_vma; struct vm_area_struct *vma; @@ -883,8 +1032,11 @@ static int try_to_unmap_anon(struct page *page, int migration) 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)) + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; + ret = try_to_unmap_one(page, vma, address, flags); + if (ret != SWAP_AGAIN || !page_mapped(page)) break; } @@ -893,16 +1045,21 @@ static int try_to_unmap_anon(struct page *page, int migration) } /** - * try_to_unmap_file - unmap file page using the object-based rmap method - * @page: the page to unmap - * @migration: migration flag + * try_to_unmap_file - unmap/unlock file page using the object-based rmap method + * @page: the page to unmap/unlock + * @flags: action and flags * * 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, enum ttu_flags flags) { struct address_space *mapping = page->mapping; pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT); @@ -916,18 +1073,27 @@ static int try_to_unmap_file(struct page *page, int migration) 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)) + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; + ret = try_to_unmap_one(page, vma, address, flags); + if (ret != SWAP_AGAIN || !page_mapped(page)) goto out; } if (list_empty(&mapping->i_mmap_nonlinear)) goto out; + /* + * We don't bother to try to find the munlocked page in nonlinears. + * It's costly. Instead, later, page reclaim logic may call + * try_to_unmap(TTU_MUNLOCK) and recover PG_mlocked lazily. + */ + if (TTU_ACTION(flags) == TTU_MUNLOCK) + goto out; + list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list) { - if ((vma->vm_flags & VM_LOCKED) && !migration) - continue; cursor = (unsigned long) vma->vm_private_data; if (cursor > max_nl_cursor) max_nl_cursor = cursor; @@ -936,7 +1102,7 @@ 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; } @@ -960,12 +1126,12 @@ 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) - 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); + if (try_to_unmap_cluster(cursor, &mapcount, + vma, page) == SWAP_MLOCK) + ret = SWAP_MLOCK; cursor += CLUSTER_SIZE; vma->vm_private_data = (void *) cursor; if ((int)mapcount <= 0) @@ -992,7 +1158,7 @@ out: /** * try_to_unmap - try to remove all page table mappings to a page * @page: the page to get unmapped - * @migration: migration flag + * @flags: action and flags * * Tries to remove all the page table entries which are mapping this * page, used in the pageout path. Caller must hold the page lock. @@ -1001,20 +1167,127 @@ 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) +int try_to_unmap(struct page *page, enum ttu_flags flags) { int ret; BUG_ON(!PageLocked(page)); - if (PageAnon(page)) - ret = try_to_unmap_anon(page, migration); + if (unlikely(PageKsm(page))) + ret = try_to_unmap_ksm(page, flags); + else if (PageAnon(page)) + ret = try_to_unmap_anon(page, flags); else - ret = try_to_unmap_file(page, migration); - - if (!page_mapped(page)) + ret = try_to_unmap_file(page, flags); + 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_AGAIN - no vma is holding page mlocked, or, + * SWAP_AGAIN - page mapped in mlocked vma -- couldn't acquire mmap sem + * SWAP_FAIL - page cannot be located at present + * SWAP_MLOCK - page is now mlocked. + */ +int try_to_munlock(struct page *page) +{ + VM_BUG_ON(!PageLocked(page) || PageLRU(page)); + + if (unlikely(PageKsm(page))) + return try_to_unmap_ksm(page, TTU_MUNLOCK); + else if (PageAnon(page)) + return try_to_unmap_anon(page, TTU_MUNLOCK); + else + return try_to_unmap_file(page, TTU_MUNLOCK); +} + +#ifdef CONFIG_MIGRATION +/* + * rmap_walk() and its helpers rmap_walk_anon() and rmap_walk_file(): + * Called by migrate.c to remove migration ptes, but might be used more later. + */ +static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, + struct vm_area_struct *, unsigned long, void *), void *arg) +{ + struct anon_vma *anon_vma; + struct vm_area_struct *vma; + int ret = SWAP_AGAIN; + + /* + * Note: remove_migration_ptes() cannot use page_lock_anon_vma() + * because that depends on page_mapped(); but not all its usages + * are holding mmap_sem, which also gave the necessary guarantee + * (that this anon_vma's slab has not already been destroyed). + * This needs to be reviewed later: avoiding page_lock_anon_vma() + * is risky, and currently limits the usefulness of rmap_walk(). + */ + anon_vma = page_anon_vma(page); + if (!anon_vma) + return ret; + spin_lock(&anon_vma->lock); + list_for_each_entry(vma, &anon_vma->head, anon_vma_node) { + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; + ret = rmap_one(page, vma, address, arg); + if (ret != SWAP_AGAIN) + break; + } + spin_unlock(&anon_vma->lock); + return ret; +} + +static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, + struct vm_area_struct *, unsigned long, void *), void *arg) +{ + 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 ret = SWAP_AGAIN; + + if (!mapping) + return ret; + spin_lock(&mapping->i_mmap_lock); + vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) { + unsigned long address = vma_address(page, vma); + if (address == -EFAULT) + continue; + ret = rmap_one(page, vma, address, arg); + if (ret != SWAP_AGAIN) + break; + } + /* + * No nonlinear handling: being always shared, nonlinear vmas + * never contain migration ptes. Decide what to do about this + * limitation to linear when we need rmap_walk() on nonlinear. + */ + spin_unlock(&mapping->i_mmap_lock); + return ret; +} + +int rmap_walk(struct page *page, int (*rmap_one)(struct page *, + struct vm_area_struct *, unsigned long, void *), void *arg) +{ + VM_BUG_ON(!PageLocked(page)); + + if (unlikely(PageKsm(page))) + return rmap_walk_ksm(page, rmap_one, arg); + else if (PageAnon(page)) + return rmap_walk_anon(page, rmap_one, arg); + else + return rmap_walk_file(page, rmap_one, arg); +} +#endif /* CONFIG_MIGRATION */