From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751617AbeBDJQJ (ORCPT ); Sun, 4 Feb 2018 04:16:09 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:60900 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750818AbeBDJQA (ORCPT ); Sun, 4 Feb 2018 04:16:00 -0500 Date: Sun, 4 Feb 2018 01:16:01 -0800 From: "Paul E. McKenney" To: Alan Stern Cc: Ingo Molnar , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, parri.andrea@gmail.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, boqun.feng@gmail.com, will.deacon@arm.com, peterz@infradead.org, npiggin@gmail.com, dhowells@redhat.com, elena.reshetova@intel.com, mhocko@suse.com, akiyks@gmail.com, Thomas Gleixner , Peter Zijlstra , Linus Torvalds Subject: Re: [GIT PULL tools] Linux kernel memory model Reply-To: paulmck@linux.vnet.ibm.com References: <20180203084809.GE3617@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18020409-0044-0000-0000-000003DB36DB X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008468; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000248; SDB=6.00984726; UDB=6.00499587; IPR=6.00764097; BA=6.00005811; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00019359; XFM=3.00000015; UTC=2018-02-04 09:15:58 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18020409-0045-0000-0000-0000080AA497 Message-Id: <20180204091601.GO3617@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-02-03_07:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1802040121 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Feb 03, 2018 at 05:10:06PM -0500, Alan Stern wrote: > On Sat, 3 Feb 2018, Paul E. McKenney wrote: > > > Please see below for an initial patch to this effect. This activity > > proved to be more productive than expected for these tests, which certainly > > supports our assertion that locking needs more testing... > > > > MP+polocks.litmus > > MP+porevlocks.litmus > > > > These are allowed by the current model, which surprised me a bit, > > given that even powerpc would forbid them. Is the rationale > > that a lock-savvy compiler could pull accesses into the lock's > > critical section and then reorder those accesses? Or does this > > constitute a bug in our model of locking? > > > > (And these were allowed when I wrote recipes.txt, embarrassingly > > enough...) > > > > Z6.0+pooncelock+poonceLock+pombonce.litmus > > > > This was forbidden when I wrote recipes.txt, but now is allowed. > > The header comment for smp_mb__after_spinlock() makes it pretty > > clear that it must be forbidden. So this one is a bug in our > > model of locking. > > I just tried testing these under the most recent version of herd, and > all three were forbidden. And they do for me as well once I upgraded to the most recent version of herd. Whew!!! Boy, we weren't kidding when we said that you need to us the latest and greatest herd7, now were we? ;-) Thanx, Paul