From 28957a5467bab9ed51a237d21e31055fad987887 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi
Date: Fri, 2 Jul 2010 14:47:20 +0900
Subject: hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()

This patch fixes possible deadlock in hugepage lock_page()
by adding missing unlock_page().

libhugetlbfs test will hit this bug when the next patch in this
patchset ("hugetlb, HWPOISON: move PG_HWPoison bit check") is applied.

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Acked-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 mm/hugetlb.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

(limited to 'mm')

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3c275ffd32a7..303fb0c02364 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2324,9 +2324,11 @@ retry_avoidcopy:
 	 * and just make the page writable */
 	avoidcopy = (page_mapcount(old_page) == 1);
 	if (avoidcopy) {
-		if (!trylock_page(old_page))
+		if (!trylock_page(old_page)) {
 			if (PageAnon(old_page))
 				page_move_anon_rmap(old_page, vma, address);
+		} else
+			unlock_page(old_page);
 		set_huge_ptep_writable(vma, address, ptep);
 		return 0;
 	}
-- 
cgit v1.2.3