From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759512AbZKZOJU (ORCPT ); Thu, 26 Nov 2009 09:09:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753463AbZKZOJT (ORCPT ); Thu, 26 Nov 2009 09:09:19 -0500 Received: from casper.infradead.org ([85.118.1.10]:56523 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750897AbZKZOJT (ORCPT ); Thu, 26 Nov 2009 09:09:19 -0500 Subject: Re: [patch] sched: fix set_task_cpu() and provide an unlocked runqueue variant From: Peter Zijlstra To: Mike Galbraith Cc: Ingo Molnar , LKML In-Reply-To: <1259230578.15079.12.camel@marge.simson.net> References: <1258891781.14325.34.camel@marge.simson.net> <1259173672.4027.732.camel@laptop> <1259197270.6186.17.camel@marge.simson.net> <1259199068.6186.33.camel@marge.simson.net> <1259228139.4273.6.camel@twins> <1259230578.15079.12.camel@marge.simson.net> Content-Type: text/plain; charset="UTF-8" Date: Thu, 26 Nov 2009 15:09:23 +0100 Message-ID: <1259244563.31676.53.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2009-11-26 at 11:16 +0100, Mike Galbraith wrote: > > min_vruntime should only ever be poked at when holding the respective > > rq->lock, even with a barrier a 64bit read on a 32bit machine can go all > > funny. > > Yeah, but we're looking at an unlocked runqueue. But never mind... The patch is also poking at rq->clock without rq->lock held... not very nice. Gah, I hate that we're doing migration things without holding both rq's, this is making live so very interesting ;-)