Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932724AbaLBQ6p (ORCPT ); Tue, 2 Dec 2014 11:58:45 -0500 Received: from e35.co.us.ibm.com ([32.97.110.153]:49367 "EHLO e35.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932303AbaLBQ6n (ORCPT ); Tue, 2 Dec 2014 11:58:43 -0500 Date: Tue, 2 Dec 2014 08:58:35 -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: <20141202165834.GJ25340@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20141126225745.GA30346@redhat.com> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <547D7B05.6080403@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: 14120216-0013-0000-0000-000006B2D5F6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 02, 2014 at 04:40:37PM +0800, Lai Jiangshan wrote: > On 12/02/2014 03:14 AM, Paul E. McKenney wrote: > > On Sun, Nov 30, 2014 at 11:02:43PM -0200, D?niel Fraga wrote: > >> On Sun, 30 Nov 2014 16:21:19 -0800 > >> Linus Torvalds wrote: > >> > >>> Maybe you'll have to turn off RCU_CPU_STALL_VERBOSE first. > >>> > >>> Although I think you should be able to just edit the .config file, > >>> delete the like that says > >>> > >>> CONFIG_TREE_PREEMPT_RCU=y > >>> > >>> and then just do a "make oldconfig", and then verify that > >>> TREE_PREEMPT_RCU hasn't been re-enabled by some dependency. But it > >>> shouldn't have, and that "make oldconfig" should get rid of anything > >>> that depends on TREE_PREEMPT_RCU. > >> > >> Ok, I did exactly that, but CONFIG_TREE_PREEMPT_RCU is > >> re-enabled. I talked with Pranith Kumar and he suggested I could just > >> disable preemption (No Forced Preemption (Server)) and that's the only > >> way to disable CONFIG_TREE_PREEMPT_RCU. > > > > If it would help to have !CONFIG_TREE_PREEMPT_RCU with CONFIG_PREEMPT=y, > > 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) It is a really easy edit to Kconfig, but I don't want people using it in production because I really don't need the extra test scenarios. So I am happy to provide the patch below as needed, but not willing to submit it to mainline without a lot more justification. Because if it appears in mainline, people will start using it in production, whether I am doing proper testing of it or not. :-/ Thanx, Paul ------------------------------------------------------------------------ diff --git a/init/Kconfig b/init/Kconfig index 903505e66d1d..2cf71fcd514f 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -469,7 +469,7 @@ choice config TREE_RCU bool "Tree-based hierarchical RCU" - depends on !PREEMPT && SMP + depends on SMP select IRQ_WORK help This option selects the RCU implementation that is -- 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/