From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755455AbaAVLyp (ORCPT ); Wed, 22 Jan 2014 06:54:45 -0500 Received: from merlin.infradead.org ([205.233.59.134]:53044 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755238AbaAVLyo (ORCPT ); Wed, 22 Jan 2014 06:54:44 -0500 Date: Wed, 22 Jan 2014 12:54:21 +0100 From: Peter Zijlstra To: Markus Trippelsdorf Cc: linux-kernel@vger.kernel.org, Dipankar Sarma , "Paul E. McKenney" , Ingo Molnar Subject: Re: [Bisected] qemu hangs on current git Message-ID: <20140122115421.GK31570@twins.programming.kicks-ass.net> References: <20140121215119.GA389@x4> <20140122085035.GA390@x4> <20140122093755.GA388@x4> <20140122102435.GH31570@twins.programming.kicks-ass.net> <20140122114443.GA389@x4> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140122114443.GA389@x4> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 22, 2014 at 12:44:43PM +0100, Markus Trippelsdorf wrote: > On 2014.01.22 at 11:24 +0100, Peter Zijlstra wrote: > > On Wed, Jan 22, 2014 at 10:37:55AM +0100, Markus Trippelsdorf wrote: > > > git bisect points to: > > > > > > commit 8cb75e0c4ec9786b81439761eac1d18d4a931af3 > > > Author: Peter Zijlstra > > > Date: Wed Nov 20 12:22:37 2013 +0100 > > > > > > sched/preempt: Fix up missed PREEMPT_NEED_RESCHED folding > > > > > > > No idea why kvm would go funny on that, real hardware runs fine. > > > > You're running a !PREEMPT kernel, right? Does the below make any > > difference? > > Yes: CONFIG_PREEMPT_VOLUNTARY=y > And yes, your patch fixes the issue. Ah, indeed, VOLUNTARY needs this for should_resched; daft of me. Thanks for testing!