From 5322cce29ce5059eed0010f0f04ab36a83611935 Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@kernel.org>
Date: Tue, 31 Jul 2012 16:42:59 -0700
Subject: [PATCH] --- yaml --- r: 320792 b: refs/heads/master c:
 97d255c816946388bab504122937730d3447c612 h: refs/heads/master v: v3

---
 [refs]                | 2 +-
 trunk/mm/page_alloc.c | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/[refs] b/[refs]
index 902bae007af9..488913da6b5e 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: de34d965a80d0f61a354bdefa0b15a88bcff2028
+refs/heads/master: 97d255c816946388bab504122937730d3447c612
diff --git a/trunk/mm/page_alloc.c b/trunk/mm/page_alloc.c
index 18747528eec3..bb790f5919e3 100644
--- a/trunk/mm/page_alloc.c
+++ b/trunk/mm/page_alloc.c
@@ -5500,11 +5500,18 @@ __count_immobile_pages(struct zone *zone, struct page *page, int count)
 			continue;
 
 		page = pfn_to_page(check);
-		if (!page_count(page)) {
+		/*
+		 * We can't use page_count without pin a page
+		 * because another CPU can free compound page.
+		 * This check already skips compound tails of THP
+		 * because their page->_count is zero at all time.
+		 */
+		if (!atomic_read(&page->_count)) {
 			if (PageBuddy(page))
 				iter += (1 << page_order(page)) - 1;
 			continue;
 		}
+
 		if (!PageLRU(page))
 			found++;
 		/*