From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752573AbcBOSV3 (ORCPT ); Mon, 15 Feb 2016 13:21:29 -0500 Received: from mail-qk0-f194.google.com ([209.85.220.194]:33153 "EHLO mail-qk0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752248AbcBOSV1 (ORCPT ); Mon, 15 Feb 2016 13:21:27 -0500 Date: Mon, 15 Feb 2016 13:21:25 -0500 From: Tejun Heo To: Michal Hocko Cc: Mike Galbraith , LKML Subject: Re: [PATCH wq/for-4.5-fixes] workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookup Message-ID: <20160215182125.GG3965@htj.duckdns.org> References: <1454424264.11183.46.camel@gmail.com> <20160203185425.GK14091@mtj.duckdns.org> <20160210155503.GE3741@mtj.duckdns.org> <20160215173346.GA26207@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160215173346.GA26207@dhcp22.suse.cz> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, Michal. On Mon, Feb 15, 2016 at 06:33:46PM +0100, Michal Hocko wrote: > On Wed 10-02-16 10:55:03, Tejun Heo wrote: > [...] > > --- a/kernel/workqueue.c > > +++ b/kernel/workqueue.c > > @@ -570,6 +570,16 @@ static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, > > int node) > > { > > assert_rcu_or_wq_mutex_or_pool_mutex(wq); > > + > > + /* > > + * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a > > + * delayed item is pending. The plan is to keep CPU -> NODE > > + * mapping valid and stable across CPU on/offlines. Once that > > + * happens, this workaround can be removed. > > I am not sure this is completely true with the code as is currently. > Don't wee also need to use cpu_to_mem to handle memoryless CPUs? I'm not sure. I think we still wan to distinguish workers for a memoryless node from its neighboring node with memory. We don't want work items for the latter to be randomly distributed to the former after all. Thanks. -- tejun