Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946405Ab2ERXEX (ORCPT ); Fri, 18 May 2012 19:04:23 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:35668 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946376Ab2ERXEQ (ORCPT ); Fri, 18 May 2012 19:04:16 -0400 Message-Id: <20120518211602.372333802@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Fri, 18 May 2012 14:16:31 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Chris Metcalf , Mel Gorman , Hillf Danton , Hugh Dickins , Michal Hocko , KAMEZAWA Hiroyuki Subject: [ 32/54] hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow() In-Reply-To: <20120518212656.GA4992@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1739 Lines: 49 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chris Metcalf commit 4998a6c0edce7fae9c0a5463f6ec3fa585258ee7 upstream. Commit 66aebce747eaf ("hugetlb: fix race condition in hugetlb_fault()") added code to avoid a race condition by elevating the page refcount in hugetlb_fault() while calling hugetlb_cow(). However, one code path in hugetlb_cow() includes an assertion that the page count is 1, whereas it may now also have the value 2 in this path. The consensus is that this BUG_ON has served its purpose, so rather than extending it to cover both cases, we just remove it. Signed-off-by: Chris Metcalf Acked-by: Mel Gorman Acked-by: Hillf Danton Acked-by: Hugh Dickins Cc: Michal Hocko Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/hugetlb.c | 1 - 1 file changed, 1 deletion(-) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2398,7 +2398,6 @@ retry_avoidcopy: if (outside_reserve) { BUG_ON(huge_pte_none(pte)); if (unmap_ref_private(mm, vma, old_page, address)) { - BUG_ON(page_count(old_page) != 1); BUG_ON(huge_pte_none(pte)); spin_lock(&mm->page_table_lock); goto retry_avoidcopy; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/