From: Weijie Yang <weijie.yang@samsung.com>
To: kamezawa.hiroyu@jp.fujitsu.com, "'Minchan Kim'" <minchan@kernel.org>
Cc: "'Andrew Morton'" <akpm@linux-foundation.org>, mgorman@suse.de,
        mina86@mina86.com, "'linux-kernel'" <linux-kernel@vger.kernel.org>,
        "'Linux-MM'" <linux-mm@kvack.org>,
        "'Weijie Yang'" <weijie.yang.kh@gmail.com>
Subject: [PATCH 2/2] mm: page_isolation: fix zone_freepage accounting
Date: Thu, 06 Nov 2014 16:09:08 +0800
Message-id: <000101cff999$09225070$1b66f150$%yang@samsung.com>
MIME-version: 1.0
Content-type: text/plain; charset=utf-8
Content-transfer-encoding: 7bit
Thread-index: Ac/5mNNMPGw6AOdSRUi8KMXwgDh7GA==
Content-language: zh-cn
Sender: linux-kernel-owner@vger.kernel.org

If race between isolatation and allocation happens, we could need to move
some freepages to MIGRATE_ISOLATE in __test_page_isolated_in_pageblock().
The current code ignores the zone_freepage accounting after the move,
which cause the zone NR_FREE_PAGES and NR_FREE_CMA_PAGES statistics incorrect.

This patch fixes this rare issue.

Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
---
 mm/page_isolation.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index 3ddc8b3..15b51de 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -193,12 +193,15 @@ __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
 			 * is MIGRATE_ISOLATE. Catch it and move the page into
 			 * MIGRATE_ISOLATE list.
 			 */
-			if (get_freepage_migratetype(page) != MIGRATE_ISOLATE) {
+			int migratetype = get_freepage_migratetype(page);
+			if (migratetype != MIGRATE_ISOLATE) {
 				struct page *end_page;
 
 				end_page = page + (1 << page_order(page)) - 1;
 				move_freepages(page_zone(page), page, end_page,
 						MIGRATE_ISOLATE);
+				__mod_zone_freepage_state(zone,
+					-(1 << page_order(page)), migratetype);
 			}
 			pfn += 1 << page_order(page);
 		}
-- 
1.7.0.4


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/