Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933166AbaLBUsX (ORCPT ); Tue, 2 Dec 2014 15:48:23 -0500 Received: from e37.co.us.ibm.com ([32.97.110.158]:37692 "EHLO e37.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932365AbaLBUsU (ORCPT ); Tue, 2 Dec 2014 15:48:20 -0500 Date: Tue, 2 Dec 2014 12:48:12 -0800 From: "Paul E. McKenney" To: Dave Jones , Linus Torvalds , =?iso-8859-1?Q?D=E2niel?= Fraga , Sasha Levin , Linux Kernel Mailing List Subject: Re: frequent lockups in 3.18rc4 Message-ID: <20141202204812.GP25340@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> <547ccf74.a5198c0a.25de.26d9@mx.google.com> <20141202203044.GA26482@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20141202203044.GA26482@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 14120220-0025-0000-0000-000006915856 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 02, 2014 at 03:30:44PM -0500, Dave Jones wrote: > 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.. > > That combination doesn't seem possible. TREE_PREEMPT_RCU is the only > possible choice if PREEMPT=y Indeed, getting that combination requires a Kconfig patch, which I supplied below. Not for mainline, debugging only. 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/