[PATCH 3.16.y-ckt 110/130] mm/hwpoison: fix page refcount of unknown non LRU page

[Luis Henriques]

3.16.7-ckt17 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wanpeng Li <wanpeng.li at hotmail.com>

commit 4f32be677b124a49459e2603321c7a5605ceb9f8 upstream.

After trying to drain pages from pagevec/pageset, we try to get reference
count of the page again, however, the reference count of the page is not
reduced if the page is still not on LRU list.

Fix it by adding the put_page() to drop the page reference which is from
__get_any_page().

Signed-off-by: Wanpeng Li <wanpeng.li at hotmail.com>
Acked-by: Naoya Horiguchi <n-horiguchi at ah.jp.nec.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 mm/memory-failure.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index fad245565616..3fd99140bd6c 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1514,6 +1514,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
 		 */
 		ret = __get_any_page(page, pfn, 0);
 		if (!PageLRU(page)) {
+			/* Drop page reference which is from __get_any_page() */
+			put_page(page);
 			pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
 				pfn, page->flags);
 			return -EIO;