Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752141AbdLSRKO (ORCPT ); Tue, 19 Dec 2017 12:10:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:32996 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751297AbdLSRKM (ORCPT ); Tue, 19 Dec 2017 12:10:12 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9109E21893 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Tue, 19 Dec 2017 12:10:10 -0500 From: Steven Rostedt To: Dhaval Giani Cc: Peter Zijlstra , LKML , Ingo Molnar , Thomas Gleixner , Andrew Morton Subject: Re: [PATCH] lockdep: Show up to three levels for a deadlock scenario Message-ID: <20171219121010.06ad6a73@gandalf.local.home> In-Reply-To: References: <20171214123852.515257aa@gandalf.local.home> <20171214175931.mlvr7lk7bcnsqu5i@hirez.programming.kicks-ass.net> <3317dd1a-1a39-3295-eb90-538be296dff8@oracle.com> <20171219164619.ehrsqvqajj4n6wr6@hirez.programming.kicks-ass.net> <20171219115238.03dc992c@gandalf.local.home> X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1252 Lines: 46 On Tue, 19 Dec 2017 11:54:10 -0500 Dhaval Giani wrote: > On 2017-12-19 11:52 AM, Steven Rostedt wrote: > > On Tue, 19 Dec 2017 17:46:19 +0100 > > Peter Zijlstra wrote: > > > > > >> It really isn't that hard, Its mostly a question of TL;DR. > >> > >> #0 is useless and should be thrown out > >> #1 shows where we take #1 while holding #0 > >> .. > >> #n shows where we take #n while holding #n-1 > >> > >> And the bottom callstack shows where we take #0 while holding #n. Which > >> gets you a nice circle in your graph, which spells deadlock. > >> > >> Plenty people have shown they get this stuff. > > > > > > Then I suggest that you can either take my patch to improve the > > visual or remove the visual completely, as nobody cares about it. > > > > I prefer the former. As Steven has mentioned elsewhere, people find > lockdep output hard to follow (enough that he has given talks :) ) > Not to mention. There's commit logs that throw everything out except for this information. See commits: 692b48258dda 5acb3cc2c2e9 7b7622bb95eb5 478fe3037b227 fdaf0a51bad49 1ddd45f8d76f0 63aea0dbab90a 1215e51edad12 f159b3c7cd45c And those only go back to March of this year. -- Steve