From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72423C433E0 for ; Fri, 29 Jan 2021 06:22:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22AF664E02 for ; Fri, 29 Jan 2021 06:22:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232093AbhA2GWR (ORCPT ); Fri, 29 Jan 2021 01:22:17 -0500 Received: from mga05.intel.com ([192.55.52.43]:16617 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231865AbhA2GWP (ORCPT ); Fri, 29 Jan 2021 01:22:15 -0500 IronPort-SDR: Y9xzKSUZy/2YtgeHANJhrVWILabBAq0jKQDZ3hOB3G6n6+WLXCv24e2gVXGawmJqDNXQkfF8ZB PwiJScUVwAgQ== X-IronPort-AV: E=McAfee;i="6000,8403,9878"; a="265205820" X-IronPort-AV: E=Sophos;i="5.79,384,1602572400"; d="scan'208";a="265205820" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2021 22:20:26 -0800 IronPort-SDR: PTvcyZV7VwjFvWOZ32vekl7hEPMTxba1TDt8Ys39mWCvzz6H9sqmFpByvqUSBqaBvsxMhxeBX3 aOZ0fFIrHsMw== X-IronPort-AV: E=Sophos;i="5.79,384,1602572400"; d="scan'208";a="364181083" Received: from xingzhen-mobl.ccr.corp.intel.com (HELO [10.238.6.97]) ([10.238.6.97]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Jan 2021 22:20:23 -0800 Subject: Re: [workqueue] d5bff968ea: WARNING:at_kernel/workqueue.c:#process_one_work To: paulmck@kernel.org, Hillf Danton Cc: Oliver Sang , Peter Zijlstra , Lai Jiangshan , LKML , lkp@intel.com, lkp References: <20210126073925.1962-1-hdanton@sina.com> <20210127092128.2299-1-hdanton@sina.com> <20210128090905.1596-1-hdanton@sina.com> <20210128180821.GA24510@paulmck-ThinkPad-P72> From: Xing Zhengjun Message-ID: Date: Fri, 29 Jan 2021 14:20:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210128180821.GA24510@paulmck-ThinkPad-P72> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 1/29/2021 2:08 AM, Paul E. McKenney wrote: > On Thu, Jan 28, 2021 at 05:09:05PM +0800, Hillf Danton wrote: >> On Thu, 28 Jan 2021 15:52:40 +0800 Xing Zhengjun wrote: > > [ . . . ] > >>> I test the patch 4 times, no warning appears in the kernel log. >> >> Thank you so much Zhengjun! >> >> And the overall brain dump so far is >> >> 1/ before and after d5bff968ea, changing the allowed ptr at online time >> is the key to quiesce the warning in process_one_work(). >> >> 2/ marking pcpu before changing aptr in rebind_workers() is mandatory in >> regards to cutting the risk of triggering such a warning. >> >> 3/ we canot maintain such an order without quiescing the 508 warning for >> kworkers. And we have a couple of excuses to do so, a) the number of >> allowed CPUs is no longer checked in is_per_cpu_kthread() instead of >> PF_NO_SETAFFINITY, b) there is always a followup act to change the aptr >> in order to fix the number of aCPUs. >> >> 4/ same order is maintained also at rescue time. > > Just out of curiosity, does this test still fail on current mainline? > > Thanx, Paul > I test mainline v5.11-rc5, it has no issue. The issue is only for d5bff968ea which is in https://git.kernel.org/cgit/linux/kernel/git/paulmck/linux-rcu.git dev.2021.01.11b. -- Zhengjun Xing