releases/3.1.1/s390-gup_huge_pmd-return-0-if-pte-changes.patch

From 0693bc9ce2cc4f6a1b9c3c05790fc149a74c0b87 Mon Sep 17 00:00:00 2001
From: Andrea Arcangeli <aarcange@redhat.com>
Date: Wed, 2 Nov 2011 13:37:28 -0700
Subject: s390: gup_huge_pmd() return 0 if pte changes

From: Andrea Arcangeli <aarcange@redhat.com>

commit 0693bc9ce2cc4f6a1b9c3c05790fc149a74c0b87 upstream.

s390 didn't return 0 in that case, if it's rolling back the *nr pointer it
should also return zero to avoid adding pages to the array at the wrong
offset.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
 arch/s390/mm/gup.c |   21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

--- a/arch/s390/mm/gup.c
+++ b/arch/s390/mm/gup.c
@@ -93,16 +93,17 @@ static inline int gup_huge_pmd(pmd_t *pm
 		*nr -= refs;
 		while (refs--)
 			put_page(head);
-	} else {
-		/*
-		 * Any tail page need their mapcount reference taken
-		 * before we return.
-		 */
-		while (refs--) {
-			if (PageTail(tail))
-				get_huge_page_tail(tail);
-			tail++;
-		}
+		return 0;
+	}
+
+	/*
+	 * Any tail page need their mapcount reference taken before we
+	 * return.
+	 */
+	while (refs--) {
+		if (PageTail(tail))
+			get_huge_page_tail(tail);
+		tail++;
 	}
 
 	return 1;