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Date: Wed, 09 Nov 2011 13:28:28 -0800
From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org,
        alan@lxorguk.ukuu.org.uk, Andrea Arcangeli <aarcange@redhat.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Hugh Dickins <hughd@google.com>, Johannes Weiner <jweiner@redhat.com>,
        Rik van Riel <riel@redhat.com>, Mel Gorman <mgorman@suse.de>,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        David Gibson <david@gibson.dropbear.id.au>
Subject: [186/262] powerpc: gup_hugepte() avoid freeing the head page too many times
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3.0-stable review patch.  If anyone has any objections, please let me know.

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

From: Andrea Arcangeli <aarcange@redhat.com>

commit 8596468487e2062cae2aad56e973784e03959245 upstream.

We only taken "refs" pins on the head page not "*nr" pins.

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>
Acked-by: David Gibson <david@gibson.dropbear.id.au>
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/powerpc/mm/hugetlbpage.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -428,10 +428,9 @@ static noinline int gup_hugepte(pte_t *p
 
 	if (unlikely(pte_val(pte) != pte_val(*ptep))) {
 		/* Could be optimized better */
-		while (*nr) {
+		*nr -= refs;
+		while (refs--)
 			put_page(head);
-			(*nr)--;
-		}
 	}
 
 	return 1;