From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932673AbcFCLNA (ORCPT ); Fri, 3 Jun 2016 07:13:00 -0400 Received: from e06smtp09.uk.ibm.com ([195.75.94.105]:46979 "EHLO e06smtp09.uk.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932232AbcFCLM6 (ORCPT ); Fri, 3 Jun 2016 07:12:58 -0400 X-IBM-Helo: d06dlp02.portsmouth.uk.ibm.com X-IBM-MailFrom: heiko.carstens@de.ibm.com X-IBM-RcptTo: linux-kernel@vger.kernel.org;linux-s390@vger.kernel.org Date: Fri, 3 Jun 2016 13:12:50 +0200 From: Heiko Carstens To: Peter Zijlstra Cc: Alfredo Alvarez Fernandez , Ingo Molnar , Shuah Khan , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [lockdep] chain_key collision check triggers Message-ID: <20160603111250.GB3472@osiris> References: <20160603071544.GA3472@osiris> <20160603084801.GG3190@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160603084801.GG3190@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16060311-0037-0000-0000-00001135A686 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 03, 2016 at 10:48:01AM +0200, Peter Zijlstra wrote: > On Fri, Jun 03, 2016 at 09:15:44AM +0200, Heiko Carstens wrote: > > Hi all, > > > > the new lockdep chain_key collision detection code triggers quite reliably > > on s390, so it looks like we need a different iterate_chain_key() > > implementation? > > That too, I have one queued up; but if you can realiably trigger this > that's 'good' news. Most reports so far have been one offs that people > could not reproduce. > > Let me wake up a bit more, but in the meantime, the below is what I had > queued. > > --- > Subject: locking,lockdep: Use __jhash_mix for iterate_chain_key > From: Peter Zijlstra > Date: Mon May 30 18:31:33 CEST 2016 > > Use __jhash_mix() to mix the class_idx into the class_key. This > function provides better mixing than the previously used, home grown > mix function. Ok, thanks! I'll use that then. Unfortunately the new hash function generates 28 instead of 2 instructions on s390.