From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Date: Fri, 2 Jul 2010 05:47:20 +0000 (+0900)
Subject: hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()
X-Git-Tag: upstream/snapshot3+hdmi~13268^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=28957a5467bab9ed51a237d21e31055fad987887;p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git

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>
---

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3c275ff..303fb0c 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;
 	}