From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751673AbdK3IIQ (ORCPT ); Thu, 30 Nov 2017 03:08:16 -0500 Received: from mail-wm0-f43.google.com ([74.125.82.43]:42673 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750890AbdK3IIO (ORCPT ); Thu, 30 Nov 2017 03:08:14 -0500 X-Google-Smtp-Source: AGs4zMbwOv+kNsD7U4GSSpKq+741tLKTkEYMj7SJ1yqbbz5B3tbOs4lVganplCWvd9n/1MpKtfOUAQ== Date: Thu, 30 Nov 2017 09:08:10 +0100 From: Daniel Vetter To: Peter Zijlstra Cc: Daniel Vetter , LKML , Ingo Molnar , Thomas Gleixner , Intel Graphics Development , Tejun Heo , Kees Cook , Tvrtko Ursulin , Marta Lofstedt , Daniel Vetter Subject: Re: [PATCH 2/2] lockdep: Up MAX_LOCKDEP_CHAINS Message-ID: <20171130080810.vedn2ivhurgnsu62@phenom.ffwll.local> Mail-Followup-To: Peter Zijlstra , LKML , Ingo Molnar , Thomas Gleixner , Intel Graphics Development , Tejun Heo , Kees Cook , Tvrtko Ursulin , Marta Lofstedt , Daniel Vetter References: <20171129154145.26755-1-daniel.vetter@ffwll.ch> <20171129154145.26755-3-daniel.vetter@ffwll.ch> <20171130074718.hzed67wrwjtv4byu@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171130074718.hzed67wrwjtv4byu@hirez.programming.kicks-ass.net> X-Operating-System: Linux phenom 4.13.0-1-amd64 User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 30, 2017 at 08:47:18AM +0100, Peter Zijlstra wrote: > On Wed, Nov 29, 2017 at 04:41:45PM +0100, Daniel Vetter wrote: > > cross-release ftl > > > > From Chris: > > > > "Fwiw, this isn't cross-release but us reloading the module many times, > > creating a whole host of new lockclasses. Even more fun is when the > > module gets a slightly different address and the new lock address hashes > > into an old lock... > > Yeah, this is a known issue, just reboot. > > > "I did think about a module-hook to revoke the stale lockclasses, but > > that still leaves all the hashed chains. > > Its an absolute royal pain to remove all the resources consumed by a > module, and if you manage you then have to deal with fragmented storage > -- that is, we need to go keep track of which entries are used. > > Its a giant heap of complexity that's just not worth it. > > > Given all that, I don't see why we should up this. Just don't reload > modules (or better, don't use modules at all). We use excessive amounts of module reloading to validate the failure paths of driver load. Rebooting takes too much time. I guess we could look into just rebinding the driver without reloading, that should take the pain off lockdep. Meanwhile we can carry this locally. I just included this to check whether you have any plans, thanks for clarifying that this is not worth it from a core perspective to get fixed. The real issue we have in CI is the one the first patch papers over. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch