From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753629AbdEJRdo (ORCPT ); Wed, 10 May 2017 13:33:44 -0400 Received: from mail-yw0-f193.google.com ([209.85.161.193]:35438 "EHLO mail-yw0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753147AbdEJRdm (ORCPT ); Wed, 10 May 2017 13:33:42 -0400 Date: Wed, 10 May 2017 13:33:40 -0400 From: Tejun Heo To: Michael Bringmann Cc: Lai Jiangshan , linux-kernel@vger.kernel.org, Nathan Fontenot Subject: Re: [PATCH] workqueue: Ensure that cpumask set for pools created after boot Message-ID: <20170510173340.GF32165@htj.duckdns.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.8.2 (2017-04-18) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, May 10, 2017 at 11:48:17AM -0500, Michael Bringmann wrote: > > On NUMA systems with dynamic processors, the content of the cpumask > may change over time. As new processors are added via DLPAR operations, > workqueues are created for them. This patch ensures that the pools > created for new workqueues will be initialized with a cpumask before > the first worker is created, attached, and woken up. If the mask is > not set up, then the kernel will crash when 'wakeup_process' is unable > to find a valid CPU to which to assign the new worker. > > Signed-off-by: Michael Bringmann > --- > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index c74bf39..6091069 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -3366,6 +3366,8 @@ static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) > copy_workqueue_attrs(pool->attrs, attrs); > pool->node = target_node; > > + cpumask_copy(pool->attrs->cpumask, cpumask_of(smp_processor_id())); What prevents a cpu getting added right here tho? Maybe the right thing to do is protecting the whole thing with hotplug readlock? Thanks. -- tejun