linux-kernel - [PATCH v2 1/5] mm/memory-failure: unlock_page before put

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Message-ID: <1438325105-10059-2-git-send-email-n-horiguchi@ah.jp.nec.com>
Date:	Fri, 31 Jul 2015 06:46:12 +0000
From:	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Andi Kleen <andi@...stfloor.org>, Dean Nelson <dnelson@...hat.com>,
	"Tony Luck" <tony.luck@...el.com>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	"Hugh Dickins" <hughd@...gle.com>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Naoya Horiguchi" <nao.horiguchi@...il.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Subject: [PATCH v2 1/5] mm/memory-failure: unlock_page before put_page

In "just unpoisoned" path, we do put_page and then unlock_page, which is a
wrong order and causes "freeing locked page" bug. So let's fix it.

Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
---
 mm/memory-failure.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git v4.2-rc4.orig/mm/memory-failure.c v4.2-rc4/mm/memory-failure.c
index c53543d89282..04d677048af7 100644
--- v4.2-rc4.orig/mm/memory-failure.c
+++ v4.2-rc4/mm/memory-failure.c
@@ -1209,9 +1209,9 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 	if (!PageHWPoison(p)) {
 		printk(KERN_ERR "MCE %#lx: just unpoisoned\n", pfn);
 		atomic_long_sub(nr_pages, &num_poisoned_pages);
+		unlock_page(hpage);
 		put_page(hpage);
-		res = 0;
-		goto out;
+		return 0;
 	}
 	if (hwpoison_filter(p)) {
 		if (TestClearPageHWPoison(p))
-- 
2.4.3
--
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