From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gum.cmpxchg.org ([85.214.110.215]:51818 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932875AbeEWNPt (ORCPT ); Wed, 23 May 2018 09:15:49 -0400 Date: Wed, 23 May 2018 09:17:47 -0400 From: Johannes Weiner To: Vinayak Menon Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, cgroups@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Andrew Morton , Tejun Heo , Balbir Singh , Mike Galbraith , Oliver Yang , Shakeel Butt , xxx xxx , Taras Kondratiuk , Daniel Walker , Ruslan Ruslichenko , kernel-team@fb.com Subject: Re: [PATCH 6/7] psi: pressure stall information for CPU, memory, and IO Message-ID: <20180523131747.GA4086@cmpxchg.org> References: <20180507210135.1823-1-hannes@cmpxchg.org> <20180507210135.1823-7-hannes@cmpxchg.org> <87060553-2e09-2e2a-13a2-a91345d6df30@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <87060553-2e09-2e2a-13a2-a91345d6df30@codeaurora.org> Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org On Wed, May 09, 2018 at 04:33:24PM +0530, Vinayak Menon wrote: > On 5/8/2018 2:31 AM, Johannes Weiner wrote: > > + /* Kick the stats aggregation worker if it's gone to sleep */ > > + if (!delayed_work_pending(&group->clock_work)) > > This causes a crash when the work is scheduled before system_wq is up. In my case when the first > schedule was called from kthreadd. And I had to do this to make it work. > if (keventd_up() && !delayed_work_pending(&group->clock_work)) > > > + schedule_delayed_work(&group->clock_work, MY_LOAD_FREQ); I was trying to figure out how this is possible, and it didn't make sense because we do initialize the system_wq way before kthreadd. Did you by any chance backport this to a pre-4.10 kernel which does not have 3347fa092821 ("workqueue: make workqueue available early during boot") yet? > > +void psi_task_change(struct task_struct *task, u64 now, int clear, int set) > > +{ > > + struct cgroup *cgroup, *parent; > > unused variables They're used in the next patch, I'll fix that up. Thanks