Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933580AbaLBTcR (ORCPT ); Tue, 2 Dec 2014 14:32:17 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35003 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932967AbaLBTcN (ORCPT ); Tue, 2 Dec 2014 14:32:13 -0500 Date: Tue, 2 Dec 2014 14:31:59 -0500 From: Dave Jones To: Linus Torvalds Cc: =?iso-8859-1?Q?D=E2niel?= Fraga , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List Subject: Re: frequent lockups in 3.18rc4 Message-ID: <20141202193159.GA17595@redhat.com> Mail-Followup-To: Dave Jones , Linus Torvalds , =?iso-8859-1?Q?D=E2niel?= Fraga , Sasha Levin , "Paul E. McKenney" , Linux Kernel Mailing List References: <20141127225637.GA24019@redhat.com> <547b8a45.6e608c0a.20f9.1002@mx.google.com> <547bbe36.48548c0a.105c.779c@mx.google.com> <20141201191431.GA17385@linux.vnet.ibm.com> <547ccf74.a5198c0a.25de.26d9@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 01, 2014 at 12:36:34PM -0800, Linus Torvalds wrote: > On Mon, Dec 1, 2014 at 12:28 PM, D?niel Fraga wrote: > > > > Hi Paul. Please, I'd like the patch, because without > > preemption, I'm unable to trigger this bug. > > Ok, that's already interesting information. And yes, it would probably > be interesting to see if CONFIG_PREEMPT=y but !CONFIG_TREE_PREEMPT_RCU > then solves it too, to narrow it down to one but not the other.. > > DaveJ - what about your situation? The standard Fedora kernels use > CONFIG_PREEMPT_VOLUNTARY, do you have CONFIG_PREEMPT and > CONFIG_TREE_PREEMPT_RCU enabled? I periodically switch PREEMPT options, just to see if anything new falls out, though I've been on CONFIG_PREEMPT for quite a while. So right now I'm testing the TREE_PREEMPT_RCU case. I'm in the process of bisecting 3.16 -> 3.17 (currently on -rc1) Thanksgiving kind of screwed up my flow, but 3.16 got a real pounding for over 3 days with no problems. I can give a !PREEMPT_RCU build a try, in case that turns out to point to something quicker than a bisect is going to. > I think you and Sasha both saw some RCU oddities too, no? I don't recall a kernel where I didn't see RCU oddities of some description, but in recent times, not so much, though a few releases back I did change some of the RCU related CONFIG options while Paul & co were chasing down some bugs. These days I've been running with.. # RCU Subsystem CONFIG_TREE_PREEMPT_RCU=y CONFIG_PREEMPT_RCU=y # CONFIG_TASKS_RCU is not set CONFIG_RCU_STALL_COMMON=y # CONFIG_RCU_USER_QS is not set CONFIG_RCU_FANOUT=64 CONFIG_RCU_FANOUT_LEAF=16 # CONFIG_RCU_FANOUT_EXACT is not set CONFIG_TREE_RCU_TRACE=y CONFIG_RCU_BOOST=y CONFIG_RCU_BOOST_PRIO=1 CONFIG_RCU_BOOST_DELAY=500 CONFIG_RCU_NOCB_CPU=y # CONFIG_RCU_NOCB_CPU_NONE is not set # CONFIG_RCU_NOCB_CPU_ZERO is not set CONFIG_RCU_NOCB_CPU_ALL=y CONFIG_DEBUG_OBJECTS_RCU_HEAD=y # RCU Debugging CONFIG_SPARSE_RCU_POINTER=y # CONFIG_RCU_TORTURE_TEST is not set CONFIG_RCU_CPU_STALL_TIMEOUT=60 CONFIG_RCU_CPU_STALL_VERBOSE=y CONFIG_RCU_CPU_STALL_INFO=y CONFIG_RCU_TRACE=y Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/