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authorRobin Holt <holt@sgi.com>2010-03-23 16:35:26 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-03-24 19:31:20 -0400
commitcb53237513bd1e090cce120efe12ede72c932b5f (patch)
tree43d0665b57b654cf10ea12233e8234367e1634e0
parent20072205fcdf7d85cd3101f1f11dfab333c5fd0c (diff)
mm/ksm.c is doing an unneeded _notify in write_protect_page.
ksm.c's write_protect_page implements a lockless means of verifying a page does not have any users of the page which are not accounted for via other kernel tracking means. It does this by removing the writable pte with TLB flushes, checking the page_count against the total known users, and then using set_pte_at_notify to make it a read-only entry. An unneeded mmu_notifier callout is made in the case where the known users does not match the page_count. In that event, we are inserting the identical pte and there is no need for the set_pte_at_notify, but rather the simpler set_pte_at suffices. Signed-off-by: Robin Holt <holt@sgi.com> Acked-by: Izik Eidus <ieidus@redhat.com> Acked-by: Andrea Arcangeli <aarcange@redhat.com> Acked-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Chris Wright <chrisw@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/ksm.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index a93f1b7f508c..8cdfc2a1e8bf 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -751,7 +751,7 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
751 * page 751 * page
752 */ 752 */
753 if (page_mapcount(page) + 1 + swapped != page_count(page)) { 753 if (page_mapcount(page) + 1 + swapped != page_count(page)) {
754 set_pte_at_notify(mm, addr, ptep, entry); 754 set_pte_at(mm, addr, ptep, entry);
755 goto out_unlock; 755 goto out_unlock;
756 } 756 }
757 entry = pte_wrprotect(entry); 757 entry = pte_wrprotect(entry);