From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756696Ab1GJVrE (ORCPT ); Sun, 10 Jul 2011 17:47:04 -0400 Received: from e5.ny.us.ibm.com ([32.97.182.145]:52175 "EHLO e5.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707Ab1GJVrB (ORCPT ); Sun, 10 Jul 2011 17:47:01 -0400 Date: Sun, 10 Jul 2011 14:46:39 -0700 From: "Paul E. McKenney" To: julie Sullivan Cc: linux-kernel@vger.kernel.org Subject: Re: PROBLEM: 3.0-rc kernels unbootable since -rc3 Message-ID: <20110710214639.GP6014@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com References: <20110707195845.GD6014@linux.vnet.ibm.com> <201107072147.12751.kernelmail.jms@gmail.com> <20110708002903.GI6014@linux.vnet.ibm.com> <20110709100900.GB6014@linux.vnet.ibm.com> <20110710032510.GG6014@linux.vnet.ibm.com> <20110710171626.GK6014@linux.vnet.ibm.com> <20110710173530.GA16954@linux.vnet.ibm.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/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jul 10, 2011 at 09:30:58PM +0100, julie Sullivan wrote: > > But maybe not that much thought.  My current guess is that your > > configuration is somehow causing some RCU callbacks to be executed > > during early boot, and that these callbacks are attempting to use kernel > > features that are not yet initialized.  If my guess is correct, then > > the reason that enabling RCU_BOOST makes things work is that it prevents > > RCU callbacks from executing until after the scheduler is up and running. > > > > So I added another commit to the jms.2011.07.07a branch in the -rcu > > git tree.  If my guesses are correct, this will allow your system to > > boot, possibly emitting a warning on the way up.  When you get a chance > > to try this out, please let me know how it goes. > > > >                                                        Thanx, Paul > > Fantastic, now we boot perfectly! > I also tried the same treatment on v3.0-rc5 and -rc6 (i.e. revert > f8b7fc6b514f34a51875 and a46e0899eec7a3069bcad then add those > 8 commits from the jms.2011.07.07a branch) with the same success. > > Thanks for giving me back 3.0-rc4, -rc5 and -rc6! Very cool! Thank you very much for the testing -- I will put together an upstreamable commit with your Tested-by. Thanx, Paul