mm: speed up cancel_dirty_page() for clean pages

[sfrench/cifs-2.6.git] / mm / ksm.c

diff --git a/mm/ksm.c b/mm/ksm.c
index 6cb60f46cce55761b0ff9d3523be69a706523972..be8f4576f84211499e269f4c69f993a975a8e0a9 100644 (file)
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1052,8 +1052,13 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
                 * So we clear the pte and flush the tlb before the check
                 * this assure us that no O_DIRECT can happen after the check
                 * or in the middle of the check.
+                *
+                * No need to notify as we are downgrading page table to read
+                * only not changing it to point to a new page.
+                *
+                * See Documentation/vm/mmu_notifier.txt
                 */
-               entry = ptep_clear_flush_notify(vma, pvmw.address, pvmw.pte);
+               entry = ptep_clear_flush(vma, pvmw.address, pvmw.pte);
                /*
                 * Check that no O_DIRECT or similar I/O is in progress on the
                 * page
@@ -1136,7 +1141,13 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
        }
 
        flush_cache_page(vma, addr, pte_pfn(*ptep));
-       ptep_clear_flush_notify(vma, addr, ptep);
+       /*
+        * No need to notify as we are replacing a read only page with another
+        * read only page with the same content.
+        *
+        * See Documentation/vm/mmu_notifier.txt
+        */
+       ptep_clear_flush(vma, addr, ptep);
        set_pte_at_notify(mm, addr, ptep, newpte);
 
        page_remove_rmap(page, false);