From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754178AbcKURGR (ORCPT ); Mon, 21 Nov 2016 12:06:17 -0500 Received: from one.firstfloor.org ([193.170.194.197]:51247 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752988AbcKURGQ (ORCPT ); Mon, 21 Nov 2016 12:06:16 -0500 Date: Mon, 21 Nov 2016 09:06:13 -0800 From: Andi Kleen To: Peter Zijlstra Cc: Jiri Olsa , Steven Rostedt , "Paul E. McKenney" , linux-kernel@vger.kernel.org, Ingo Molnar , Josh Triplett , Andi Kleen , Jan Stancek Subject: Re: [BUG] msr-trace.h:42 suspicious rcu_dereference_check() usage! Message-ID: <20161121170612.GT26852@two.firstfloor.org> References: <20161121005343.GB1891@krava> <20161121092850.GF3102@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161121092850.GF3102@twins.programming.kicks-ass.net> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > it got away with attached change.. but this rcu logic > > is far beyond me, so it's just wild guess.. ;-) > > I think I prefer something like the below, that only annotates the one > RDMSR in question, instead of all of them. It would be far better to just fix trace points that they always work. This whole thing is a travesty: we have tens of thousands of lines of code in ftrace to support tracing in NMIs, but then "debug features"[1] like this come around and make trace points unusable for far more code than just the NMI handlers. -Andi [1] unclear what they actually "debug" here.