Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752371AbdIEHTm (ORCPT ); Tue, 5 Sep 2017 03:19:42 -0400 Received: from merlin.infradead.org ([205.233.59.134]:49278 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752067AbdIEHTj (ORCPT ); Tue, 5 Sep 2017 03:19:39 -0400 Date: Tue, 5 Sep 2017 09:19:30 +0200 From: Peter Zijlstra To: Byungchul Park Cc: Byungchul Park , Ingo Molnar , Tejun Heo , Boqun Feng , david@fromorbit.com, Johannes Berg , oleg@redhat.com, "linux-kernel@vger.kernel.org" , kernel-team@lge.com Subject: Re: [PATCH 4/4] lockdep: Fix workqueue crossrelease annotation Message-ID: <20170905071930.h6t2f4guvmswibnv@hirez.programming.kicks-ass.net> References: <20170901020512.GK3240@X58A-UD3R> <20170901094747.iv6s532ccuuzpry2@hirez.programming.kicks-ass.net> <20170901101629.GL3240@X58A-UD3R> <20170901123856.p2trpebau57yxftc@hirez.programming.kicks-ass.net> <20170901163852.ckslrgldsalqmg3c@hirez.programming.kicks-ass.net> <20170904013031.GM3240@X58A-UD3R> <20170904114248.kls4jv2ggsv46mli@hirez.programming.kicks-ass.net> <20170905003844.GO3240@X58A-UD3R> <20170905070825.tovfkqvxpwosh5oa@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170905070825.tovfkqvxpwosh5oa@hirez.programming.kicks-ass.net> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 810 Lines: 21 On Tue, Sep 05, 2017 at 09:08:25AM +0200, Peter Zijlstra wrote: > So you worry about max_active==1 ? Or you worry about pool->lock or > about the thread setup? I'm still not sure. So the thing about pool->lock is that its a leaf lock, we take nothing inside it. Futhermore its a spinlock and therefore blocking things like completions or page-lock cannot form a deadlock with it. It is also fully isolated inside workqueue.c and easy to audit. This is why I really can't be arsed about it. And the whole setup stuff isn't properly preserved between works in any case, only the first few works would ever see that history, so why bother. We _could_ save/restore the setup history, by doing a complete copy of it and restoring that, but that's not what crossrelease did, and I really don't see the point.