From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F23BAC43603 for ; Mon, 1 Mar 2021 21:25:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B47B560231 for ; Mon, 1 Mar 2021 21:25:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244712AbhCAVZU (ORCPT ); Mon, 1 Mar 2021 16:25:20 -0500 Received: from mail.kernel.org ([198.145.29.99]:48350 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237327AbhCARPt (ORCPT ); Mon, 1 Mar 2021 12:15:49 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2F41164F95; Mon, 1 Mar 2021 16:45:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614617154; bh=BgEBO1YfcoTcNSvVv4L2rDo6/saPOBPSddSbNh3hoeg=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=RAimudY26B/q7zpn7QUYAmgQGiBDhOU28tUGaSwdmUodjYeIgpTimn5H2s/giTjUG 1PhAMZo01o7fWuo5sXj9PPCAg0ybYMNI2R4EdJARnLqD5jZocOxQJbhCvSODTIOxz6 A3LD5LXeCL2Y3rvq+zFsLomQI4imt076IzaeoQdXHT4tQQzn5dAnW+Pnj2lJKOxoCs gmdMCioWMTytDkTpxgzDspUVUhBCLzg4aRH6iMsS1Ve8/OnmjR9vuYSocHkeKEjAeg VoNuJ+pmwtqfYOFhPRPxp0vS+WcEQv+aT6MxZmpeNE4G5dBJPiaIKsn4hNmMOpTWku p3BBz/Gulyk7A== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id C1E4735225E7; Mon, 1 Mar 2021 08:45:53 -0800 (PST) Date: Mon, 1 Mar 2021 08:45:53 -0800 From: "Paul E. McKenney" To: =?iso-8859-1?Q?J=FCrgen_Gro=DF?= Cc: Peter Zijlstra , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, mhocko@suse.com, Jonathan Corbet Subject: Re: [PATCH 3/3] kernel/smp: add more data to CSD lock debugging Message-ID: <20210301164553.GI2696@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20210226112521.8641-1-jgross@suse.com> <20210226112521.8641-4-jgross@suse.com> <20210226181205.GZ2743@paulmck-ThinkPad-P72> <20210301000704.GF2696@paulmck-ThinkPad-P72> <6bc3d90d-f369-e91d-01f7-b83a48e9721d@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6bc3d90d-f369-e91d-01f7-b83a48e9721d@suse.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 01, 2021 at 04:53:27PM +0100, Jürgen Groß wrote: > On 01.03.21 16:45, Peter Zijlstra wrote: > > On Sun, Feb 28, 2021 at 04:07:04PM -0800, Paul E. McKenney wrote: > > > On Fri, Feb 26, 2021 at 10:05:51PM +0100, Peter Zijlstra wrote: > > > > On Fri, Feb 26, 2021 at 10:12:05AM -0800, Paul E. McKenney wrote: > > > > > On Fri, Feb 26, 2021 at 05:38:44PM +0100, Peter Zijlstra wrote: > > > > > > > > > > > > I hate all of this, but if this will finally catch the actual problem, > > > > > > we can then revert all this, so sure. > > > > > > > > > > OK, I will bite... What exactly do you hate about it? > > > > > > > > It's ugly and messy. We're basically commiting a debug session. Normally > > > > gunk like this is done in private trees, then we find the problem and > > > > fix that and crap like this never sees the light of day. > > > > > > Is your hatred due to the presence of debug code at all, or a belief that > > > this code is unlikely to be useful in any subsequent IPI-related bug hunt? > > > > The clutter, mostly I think. There's a lot of debug sprinkled about. > > I agree. > > In case we are able to identify the root cause of the problem I think > it would be no problem to revert this patch and put a comment into smp.c > naming the commit-id of this patch and what it was good for. This will > enable future bug hunters to make use of the patch without spoiling the > code for others. Works for me! Thanx, Paul