Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932763AbaLBSri (ORCPT ); Tue, 2 Dec 2014 13:47:38 -0500 Received: from mail-qc0-f176.google.com ([209.85.216.176]:42807 "EHLO mail-qc0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932356AbaLBSrh (ORCPT ); Tue, 2 Dec 2014 13:47:37 -0500 Message-ID: <547e0947.c332e00a.23bf.ffffa8bd@mx.google.com> Date: Tue, 2 Dec 2014 16:47:31 -0200 From: =?UTF-8?B?RMOibmllbA==?= Fraga To: "Paul E. McKenney" Cc: Linus Torvalds , Linux Kernel Mailing List Subject: Re: frequent lockups in 3.18rc4 In-Reply-To: <20141202184202.GM25340@linux.vnet.ibm.com> References: <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> <20141201230813.GE25340@linux.vnet.ibm.com> <547dec29.c71f8c0a.33d1.11d9@mx.google.com> <20141202170407.GK25340@linux.vnet.ibm.com> <547df364.236a8c0a.7b2d.ffffac67@mx.google.com> <20141202184202.GM25340@linux.vnet.ibm.com> Organization: http://www.youtube.com/DanielFragaBR X-Mailer: Claws Mail 3.11.1-9-g1f531c (GTK+ 2.24.25; x86_64-unknown-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2 Dec 2014 10:42:02 -0800 "Paul E. McKenney" wrote: > I was actually suggesting something a bit different. Instead of bisecting > by release, bisect by code. The procedure is as follows: > > 1. I figure out some reliable way of making RCU allow preemption to > be disabled for some RCU read-side critical sections, but not for > others. I send you the patch, which has rcu_read_lock_test() > as well as rcu_read_lock(). > > 2. You build a kernel without my Kconfig hack, with my patch from > #1 above, and build a kernel with CONFIG_PREEMPT=y (which of > course implies CONFIG_TREE_PREEMPT_RCU=y, given that you are > building without my Kconfig hack). > > 3. You make a list of all the rcu_read_lock() uses in the kernel > (or ask me to provide it). You change the rcu_read_lock() > calls in the first half of this list to rcu_read_lock_test(). > > If the kernel locks up as easily with this change as it did > in a stock CONFIG_PREEMPT=y CONFIG_TREE_PREEMPT_RCU=y kernel, > change half of the remaining rcu_read_lock() calls to > rcu_read_lock_test(). If the kernel is much more resistant > to lockup, change half of the rcu_read_lock_test() calls > back to rcu_read_lock(). Ok Paul, I want to do everything I can to help you debug this. So can you provide me the list you mentioned at point 3 (or tell me how can I get it)? If you guide me through this, I can do whatever you need. Thanks! -- Linux 3.17.0-rc6-00235-gb94d525: Shuffling Zombie Juror http://www.youtube.com/DanielFragaBR http://exchangewar.info Bitcoin: 12H6661yoLDUZaYPdah6urZS5WiXwTAUgL -- 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/