From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751652AbaHHSa2 (ORCPT ); Fri, 8 Aug 2014 14:30:28 -0400 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.227]:5567 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750738AbaHHSaZ (ORCPT ); Fri, 8 Aug 2014 14:30:25 -0400 Date: Fri, 8 Aug 2014 14:30:22 -0400 From: Steven Rostedt To: "Paul E. McKenney" Cc: Dave Hansen , linux-kernel@vger.kernel.org, dave.hansen@linux.intel.com, davej@redhat.com, mingo@redhat.com Subject: Re: [PATCH] tracing: generate RCU warnings even when tracepoints are disabled Message-ID: <20140808143022.5262f6cb@gandalf.local.home> In-Reply-To: <20140807181356.GG5821@linux.vnet.ibm.com> References: <20140807175204.C257CAC5@viggo.jf.intel.com> <20140807181356.GG5821@linux.vnet.ibm.com> X-Mailer: Claws Mail 3.10.1 (GTK+ 2.24.24; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.118:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 7 Aug 2014 11:13:56 -0700 "Paul E. McKenney" wrote: > On Thu, Aug 07, 2014 at 10:52:04AM -0700, Dave Hansen wrote: > > > > From: Dave Hansen > > > > Dave Jones reported seeing a bug from one of my TLB tracepoints: > > > > http://lkml.kernel.org/r/20140806181801.GA4605@redhat.com > > > > I've been running these patches for months and never saw this. > > But, a big chunk of my testing, especially with all the debugging > > enabled, was in a vm where intel_idle doesn't work. On the > > systems where I was using intel_idle, I never had lockdep enabled > > and this tracepoint on at the same time. > > > > This patch ensures that whenever we have lockdep available, we do > > _some_ RCU activity at the site of the tracepoint, despite > > whether the tracepoint's condition matches or even if the > > tracepoint itself is completely disabled. This is a bit of a > > hack, but it is pretty self-contained. > > > > I confirmed that with this patch plus lockdep I get the same > > splat as Dave Jones did, but without enabling the tracepoint > > explicitly. > > > > Signed-off-by: Dave Hansen > > Cc: Dave Jones , > > Cc: paulmck@linux.vnet.ibm.com > > Cc: Steven Rostedt > > Cc: Ingo Molnar > > Looks good to me, but I must defer to Steven on this one. > Looks fine. I can add it to my 3.18 queue. Paul, want to send me an "Acked-by"? Thanks, -- Steve