From 89d1eee5326f6f054606e6f82aaf2025731b6686 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@suse.de>
Date: Fri, 3 Feb 2012 15:37:18 -0800
Subject: [PATCH] --- yaml --- r: 287219 b: refs/heads/master c:
 0bf380bc70ecba68cb4d74dc656cc2fa8c4d801a h: refs/heads/master i:   287217:
 3de6f9683940419b990499f37651541facfa3c24   287215:
 0a46735f59b9c46790e0307b14aafb1e9daeeed7 v: v3

---
 [refs]                |  2 +-
 trunk/mm/compaction.c | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 24ea348b35c0..eb06c8b5266b 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 3deaa7190a8da38453c4fabd9dec7f66d17fff67
+refs/heads/master: 0bf380bc70ecba68cb4d74dc656cc2fa8c4d801a
diff --git a/trunk/mm/compaction.c b/trunk/mm/compaction.c
index 71a58f67f481..bd939a574b84 100644
--- a/trunk/mm/compaction.c
+++ b/trunk/mm/compaction.c
@@ -313,6 +313,19 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
 		} else if (!locked)
 			spin_lock_irq(&zone->lru_lock);
 
+		/*
+		 * migrate_pfn does not necessarily start aligned to a
+		 * pageblock. Ensure that pfn_valid is called when moving
+		 * into a new MAX_ORDER_NR_PAGES range in case of large
+		 * memory holes within the zone
+		 */
+		if ((low_pfn & (MAX_ORDER_NR_PAGES - 1)) == 0) {
+			if (!pfn_valid(low_pfn)) {
+				low_pfn += MAX_ORDER_NR_PAGES - 1;
+				continue;
+			}
+		}
+
 		if (!pfn_valid_within(low_pfn))
 			continue;
 		nr_scanned++;