From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752024AbcEIRAT (ORCPT ); Mon, 9 May 2016 13:00:19 -0400 Received: from mail-yw0-f180.google.com ([209.85.161.180]:36682 "EHLO mail-yw0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751733AbcEIRAQ (ORCPT ); Mon, 9 May 2016 13:00:16 -0400 Date: Mon, 9 May 2016 13:00:13 -0400 From: Tejun Heo To: Wanpeng Li Cc: linux-kernel@vger.kernel.org, Wanpeng Li , Lai Jiangshan Subject: Re: [PATCH] workqueue: fix rebind bound workers warning Message-ID: <20160509170013.GI7110@mtj.duckdns.org> References: <1462412491-11156-1-git-send-email-wanpeng.li@hotmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1462412491-11156-1-git-send-email-wanpeng.li@hotmail.com> 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, On Thu, May 05, 2016 at 09:41:31AM +0800, Wanpeng Li wrote: > The boot CPU handles housekeeping duty(unbound timers, workqueues, > timekeeping, ...) on behalf of full dynticks CPUs. It must remain > online when nohz full is enabled. There is a priority set to every > notifier_blocks: > > workqueue_cpu_up > tick_nohz_cpu_down > workqueue_cpu_down > > So tick_nohz_cpu_down callback failed when down prepare cpu 0, and > notifier_blocks behind tick_nohz_cpu_down will not be called any > more, which leads to workers are actually not unbound. Then hotplug > state machine will fallback to undo and online cpu 0 again. Workers > will be rebound unconditionally even if they are not unbound and > trigger the warning in this progress. I'm a bit confused. Are you saying that the hotplug statemachine may invoke CPU_DOWN_FAILED w/o preceding CPU_DOWN on the same callback? Thanks. -- tejun