Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932202Ab2FGNm5 (ORCPT ); Thu, 7 Jun 2012 09:42:57 -0400 Received: from mail-qa0-f46.google.com ([209.85.216.46]:40217 "EHLO mail-qa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758095Ab2FGNm4 convert rfc822-to-8bit (ORCPT ); Thu, 7 Jun 2012 09:42:56 -0400 MIME-Version: 1.0 In-Reply-To: <20120607040337.622672845@linuxfoundation.org> References: <20120607041406.GA13233@kroah.com> <20120607040337.622672845@linuxfoundation.org> Date: Thu, 7 Jun 2012 09:42:55 -0400 Message-ID: Subject: Re: [ 08/82] mm: pmd_read_atomic: fix 32bit PAE pmd walk vs pmd_populate SMP race condition From: Josh Boyer To: Greg KH Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ulrich Obergfell , Andrea Arcangeli , Mel Gorman , Hugh Dickins , Larry Woodman , Petr Matousek , Rik van Riel Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1010 Lines: 27 On Thu, Jun 7, 2012 at 12:03 AM, Greg KH wrote: > 3.4-stable review patch. ?If anyone has any objections, please let me know. > > ------------------ > > From: Andrea Arcangeli > > commit 26c191788f18129af0eb32a358cdaea0c7479626 upstream. > > When holding the mmap_sem for reading, pmd_offset_map_lock should only > run on a pmd_t that has been read atomically from the pmdp pointer, > otherwise we may read only half of it leading to this crash. This one is important, but it can break Xen apparently: http://permalink.gmane.org/gmane.comp.emulators.xen.devel/132522 https://bugzilla.redhat.com/show_bug.cgi?id=829016 Not sure if you want to hold off on it or see if Andrea comes up with a follow up fix? josh -- 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/