Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751524AbdIEI5k (ORCPT ); Tue, 5 Sep 2017 04:57:40 -0400 Received: from LGEAMRELO11.lge.com ([156.147.23.51]:42489 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750709AbdIEI5h (ORCPT ); Tue, 5 Sep 2017 04:57:37 -0400 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com Date: Tue, 5 Sep 2017 17:57:27 +0900 From: Byungchul Park To: Peter Zijlstra 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: <20170905085727.GV3240@X58A-UD3R> References: <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> <20170905071930.h6t2f4guvmswibnv@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170905071930.h6t2f4guvmswibnv@hirez.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 Content-Length: 1055 Lines: 26 On Tue, Sep 05, 2017 at 09:19:30AM +0200, Peter Zijlstra wrote: > 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 I think the following sentence is a key, I hope... Leaf locks can also create dependecies with *crosslocks*. These dependencies are not built between holding locks like typical locks. > inside it. Futhermore its a spinlock and therefore blocking things like > completions or page-lock cannot form a deadlock with it. I agree. Now we should be only interested in blocking things. > 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. As I said in another reply, what about (1), (3) and (5) in my example?