[PATCH] mm: rmap.c cleanup
mm/rmap.c:page_referenced_one() and mm/rmap.c:try_to_unmap_one() contain
identical code that
- takes mm->page_table_lock;
- drills through page tables;
- checks that correct pte is reached.
Coalesce this into page_check_address()
Signed-off-by: Nikita Danilov <nikita@clusterfs.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/mm/rmap.c b/mm/rmap.c
index 884d6d1..378de23 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -243,6 +243,42 @@
}
/*
+ * 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 @@
{
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 @@
if (address == -EFAULT)
goto out;
- spin_lock(&mm->page_table_lock);
+ pte = page_check_address(page, mm, address);
+ if (!IS_ERR(pte)) {
+ if (ptep_clear_flush_young(vma, address, pte))
+ referenced++;
- pgd = pgd_offset(mm, address);
- if (!pgd_present(*pgd))
- goto out_unlock;
+ if (mm != current->mm && !ignore_token && has_swap_token(mm))
+ referenced++;
- 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++;
-
- (*mapcount)--;
-
-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 @@
{
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 @@
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 @@
out_unmap:
pte_unmap(pte);
-out_unlock:
spin_unlock(&mm->page_table_lock);
out:
return ret;
@@ -708,7 +695,6 @@
}
pte_unmap(pte);
-
out_unlock:
spin_unlock(&mm->page_table_lock);
}
@@ -860,3 +846,4 @@
ret = SWAP_SUCCESS;
return ret;
}
+