From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755210AbaLHLfo (ORCPT ); Mon, 8 Dec 2014 06:35:44 -0500 Received: from e06smtp17.uk.ibm.com ([195.75.94.113]:53756 "EHLO e06smtp17.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753291AbaLHLfm (ORCPT ); Mon, 8 Dec 2014 06:35:42 -0500 Message-ID: <54858D07.2030403@de.ibm.com> Date: Mon, 08 Dec 2014 12:35:35 +0100 From: Christian Borntraeger User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.2.0 MIME-Version: 1.0 To: Stephen Rothwell , Benjamin Herrenschmidt , linuxppc-dev@lists.ozlabs.org, Michael Ellerman CC: linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" , Linus Torvalds Subject: Re: linux-next: build failure after merge of the access_once tree References: <20141208222641.40a64946@canb.auug.org.au> In-Reply-To: <20141208222641.40a64946@canb.auug.org.au> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14120811-0029-0000-0000-00000211B9B7 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 08.12.2014 um 12:26 schrieb Stephen Rothwell: > Hi Christian, > > After merging the acess_once tree, today's linux-next build (powerpc > allnoconfig) failed like this: > > arch/powerpc/mm/hugetlbpage.c: In function 'find_linux_pte_or_hugepte': > arch/powerpc/mm/hugetlbpage.c:981:3: error: invalid initializer > pud = ACCESS_ONCE(*pudp); > ^ > arch/powerpc/mm/hugetlbpage.c:993:4: error: invalid initializer > pmd = ACCESS_ONCE(*pmdp); > ^ > > These are preexisting ... > > mm/gup.c: In function 'gup_pmd_range': > mm/gup.c:929:3: error: invalid initializer > pmd_t pmd = ACCESS_ONCE(*pmdp); > ^ > mm/gup.c:929:3: error: (near initialization for 'pmd') > > This is from commit f30c59e921f1 ("mm: Update generic gup > implementation to handle hugepage directory") from the powerpc-mpe (and > powerpc) tree and so will require a merge fix patch (presumable > s/ACCESS_ONCE/READ_ONCE/). > > I am not sure how many architectures you are trying to cover, but > powerpc is one I care about :-) > > I have dropped the access_once tree again today, sorry (its too late at > night). Yes, we expect that tightening ACCESS_ONCE will trigger these bugs. I tried to cover everything in Linus master, but next is certainly a new game. It will be pretty hard for me to keep this running when hundreds of trees get merged during 3.19-rc. :-( Linus, I see two options: a: Either we go a full round in linux-next and expect all trees to follow the new rules, so we can merge this for 3.20 b: Only apply READ/ASSIGN_ONCE and the first fixups for 3.19 and put the ACCESS_ONCE change in next after rc1 so it will go in for 3.20 (or later) so that people can adopt. Any opinions? Christian