diff options
| -rw-r--r-- | mm/rmap.c | 113 |
1 files changed, 50 insertions, 63 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 884d6d1928b..378de234c12 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -243,6 +243,42 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) } /* + * Check that @page is mapped at @address into @mm. + * + * On success returns with mapped pte and locked mm->page_table_lock. + */ +static pte_t *page_check_address(struct page *page, struct mm_struct *mm, + unsigned long address) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + + /* + * We need the page_table_lock to protect us from page faults, + * munmap, fork, etc... + */ + spin_lock(&mm->page_table_lock); + pgd = pgd_offset(mm, address); + if (likely(pgd_present(*pgd))) { + pud = pud_offset(pgd, address); + if (likely(pud_present(*pud))) { + pmd = pmd_offset(pud, address); + if (likely(pmd_present(*pmd))) { + pte = pte_offset_map(pmd, address); + if (likely(pte_present(*pte) && + page_to_pfn(page) == pte_pfn(*pte))) + return pte; + pte_unmap(pte); + } + } + } + spin_unlock(&mm->page_table_lock); + return ERR_PTR(-ENOENT); +} + +/* * Subfunctions of page_referenced: page_referenced_one called * repeatedly from either page_referenced_anon or page_referenced_file. */ @@ -251,9 +287,6 @@ static int page_referenced_one(struct page *page, { struct mm_struct *mm = vma->vm_mm; unsigned long address; - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; pte_t *pte; int referenced = 0; @@ -263,39 +296,18 @@ static int page_referenced_one(struct page *page, if (address == -EFAULT) goto out; - spin_lock(&mm->page_table_lock); - - pgd = pgd_offset(mm, address); - if (!pgd_present(*pgd)) - goto out_unlock; - - pud = pud_offset(pgd, address); - if (!pud_present(*pud)) - goto out_unlock; - - pmd = pmd_offset(pud, address); - if (!pmd_present(*pmd)) - goto out_unlock; - - pte = pte_offset_map(pmd, address); - if (!pte_present(*pte)) - goto out_unmap; - - if (page_to_pfn(page) != pte_pfn(*pte)) - goto out_unmap; - - if (ptep_clear_flush_young(vma, address, pte)) - referenced++; - - if (mm != current->mm && !ignore_token && has_swap_token(mm)) - referenced++; + pte = page_check_address(page, mm, address); + if (!IS_ERR(pte)) { + if (ptep_clear_flush_young(vma, address, pte)) + referenced++; - (*mapcount)--; + if (mm != current->mm && !ignore_token && has_swap_token(mm)) + referenced++; -out_unmap: - pte_unmap(pte); -out_unlock: - spin_unlock(&mm->page_table_lock); + (*mapcount)--; + pte_unmap(pte); + spin_unlock(&mm->page_table_lock); + } out: return referenced; } @@ -502,9 +514,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) { struct mm_struct *mm = vma->vm_mm; unsigned long address; - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; pte_t *pte; pte_t pteval; int ret = SWAP_AGAIN; @@ -515,30 +524,9 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) if (address == -EFAULT) goto out; - /* - * We need the page_table_lock to protect us from page faults, - * munmap, fork, etc... - */ - spin_lock(&mm->page_table_lock); - - pgd = pgd_offset(mm, address); - if (!pgd_present(*pgd)) - goto out_unlock; - - pud = pud_offset(pgd, address); - if (!pud_present(*pud)) - goto out_unlock; - - pmd = pmd_offset(pud, address); - if (!pmd_present(*pmd)) - goto out_unlock; - - pte = pte_offset_map(pmd, address); - if (!pte_present(*pte)) - goto out_unmap; - - if (page_to_pfn(page) != pte_pfn(*pte)) - goto out_unmap; + pte = page_check_address(page, mm, address); + if (IS_ERR(pte)) + goto out; /* * If the page is mlock()d, we cannot swap it out. @@ -604,7 +592,6 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma) out_unmap: pte_unmap(pte); -out_unlock: spin_unlock(&mm->page_table_lock); out: return ret; @@ -708,7 +695,6 @@ static void try_to_unmap_cluster(unsigned long cursor, } pte_unmap(pte); - out_unlock: spin_unlock(&mm->page_table_lock); } @@ -860,3 +846,4 @@ int try_to_unmap(struct page *page) ret = SWAP_SUCCESS; return ret; } + |