From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751447AbeECSXJ (ORCPT ); Thu, 3 May 2018 14:23:09 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:40550 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751095AbeECSXI (ORCPT ); Thu, 3 May 2018 14:23:08 -0400 Date: Thu, 3 May 2018 11:24:25 -0700 From: "Paul E. McKenney" To: Peter Zijlstra Cc: Mike Galbraith , Matt Fleming , Ingo Molnar , linux-kernel@vger.kernel.org, Michal Hocko Subject: Re: cpu stopper threads and load balancing leads to deadlock Reply-To: paulmck@linux.vnet.ibm.com References: <1525351221.9956.4.camel@gmx.de> <20180503124943.GB12217@hirez.programming.kicks-ass.net> <1525354359.5576.1.camel@gmx.de> <20180503135617.GC12217@hirez.programming.kicks-ass.net> <1525357015.5577.2.camel@gmx.de> <20180503144450.GD12217@hirez.programming.kicks-ass.net> <20180503161231.GI26088@linux.vnet.ibm.com> <20180503164508.GG12217@hirez.programming.kicks-ass.net> <20180503171850.GL26088@linux.vnet.ibm.com> <20180503175456.GI12217@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180503175456.GI12217@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 18050318-0048-0000-0000-00000267B194 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008963; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000258; SDB=6.01027002; UDB=6.00524569; IPR=6.00806135; MB=3.00020910; MTD=3.00000008; XFM=3.00000015; UTC=2018-05-03 18:23:05 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18050318-0049-0000-0000-000044FE3296 Message-Id: <20180503182425.GM26088@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-05-03_08:,, 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-1805030157 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 03, 2018 at 07:54:56PM +0200, Peter Zijlstra wrote: > On Thu, May 03, 2018 at 10:18:50AM -0700, Paul E. McKenney wrote: > > > + if (per_cpu(rcu_cpu_started, cpu)) > > > > I would log a non-splat dmesg the first time this happened, just for my > > future sanity, but otherwise looks fine. I am a bit concerned about > > calls to rcu_cpu_starting() getting sprinkled all through the code. > > Or am I being excessively paranoid? > > Don't think so, but lets first see if this at all works. If not we'll > need to figure out something else anyway. Works for me! Thanx, Paul