Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751597AbaLCFWu (ORCPT ); Wed, 3 Dec 2014 00:22:50 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:49063 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750886AbaLCFWt (ORCPT ); Wed, 3 Dec 2014 00:22:49 -0500 Date: Tue, 2 Dec 2014 21:22:45 -0800 From: "Paul E. McKenney" To: Lai Jiangshan Cc: =?iso-8859-1?Q?D=E2niel?= Fraga , Linus Torvalds , Linux Kernel Mailing List Subject: Re: frequent lockups in 3.18rc4 Message-ID: <20141203052244.GH25340@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com 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> <547D7B05.6080403@cn.fujitsu.com> <547defc3.28568c0a.73eb.1a1e@mx.google.com> <547E6F8C.1060709@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <547E6F8C.1060709@cn.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14120305-0029-0000-0000-00000611377C Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 03, 2014 at 10:03:56AM +0800, Lai Jiangshan wrote: > On 12/03/2014 12:58 AM, D?niel Fraga wrote: > > On Tue, 2 Dec 2014 16:40:37 +0800 > > Lai Jiangshan wrote: > > > >> It is needed at lest for testing. > >> > >> CONFIG_TREE_PREEMPT_RCU=y with CONFIG_PREEMPT=n is needed for testing too. > >> > >> Please enable them (or enable them under CONFIG_RCU_TRACE=y) > > > > Lai, sorry but I didn't understand. Do you mean both of them > > enabled? Because how can CONFIG_TREE_PREEMPT_RCU be enabled without > > CONFIG_PREEMPT ? > > > Sorry, I replied to Paul, and my reply was off-topic, it has nothing > related your reports. Sorry again. > > I think we need two combinations for testing (not mainline, but I think > they (combinations) should be enabled for test farms). > > So I hope Paul enable them (combinations). > > combination1: CONFIG_TREE_PREEMPT_RCU=n & CONFIG_PREEMPT=y > combination2: CONFIG_TREE_PREEMPT_RCU=y & CONFIG_PREEMPT=n > > The core code should work correctly in these combinations. > I agree with Paul that these combinations should not be enabled in production, > So my request is: enable these combinations under CONFIG_RCU_TRACE > or CONFIG_TREE_RCU_TRACE. > > For myself, I always edit the Kconfig directly, thus it is not a problem > for me. But there is no way for test farms to test these combinations. OK, I'll bite... How have these two combinations helped you in your testing? The reason I ask is that I am actually trying to -decrease- the RCU configurations, not increase them. Added configurations need to have strong justification, for example, the kernel-tracing/patching need for tasks_rcu. Thanx, Paul > Thanks, > Lai > > > > > If you mean both enabled, I already reported a call trace with > > both enabled: > > > > https://bugzilla.kernel.org/show_bug.cgi?id=85941 > > > > Please see my previous answer to Linus and Paul too. > > > > Regarding CONFIG_RCU_TRACE, do you mean > > "CONFIG_TREE_RCU_TRACE"? I couldn't find CONFIG_RCU_TRACE. > > > > Thanks. > > > -- 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/