From 4b8708e85400f6e0c9b49c16195457fca4636b9c Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Mon, 31 Oct 2011 17:09:43 -0700
Subject: [PATCH] --- yaml --- r: 272168 b: refs/heads/master c:
 3d470fc385defa60d9af610f05db8e7f8b4f2f5e h: refs/heads/master v: v3

---
 [refs]           |  2 +-
 trunk/mm/mlock.c | 10 +++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 27f90a0c4f05..f4b62a88efa5 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 35d8c7ad7208dad5d352c483408e555022750978
+refs/heads/master: 3d470fc385defa60d9af610f05db8e7f8b4f2f5e
diff --git a/trunk/mm/mlock.c b/trunk/mm/mlock.c
index 7debb4fdf79b..bd34b3a10852 100644
--- a/trunk/mm/mlock.c
+++ b/trunk/mm/mlock.c
@@ -110,7 +110,15 @@ void munlock_vma_page(struct page *page)
 	if (TestClearPageMlocked(page)) {
 		dec_zone_page_state(page, NR_MLOCK);
 		if (!isolate_lru_page(page)) {
-			int ret = try_to_munlock(page);
+			int ret = SWAP_AGAIN;
+
+			/*
+			 * Optimization: if the page was mapped just once,
+			 * that's our mapping and we don't need to check all the
+			 * other vmas.
+			 */
+			if (page_mapcount(page) > 1)
+				ret = try_to_munlock(page);
 			/*
 			 * did try_to_unlock() succeed or punt?
 			 */