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=-7.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 7D554C433DB for ; Thu, 28 Jan 2021 18:13:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3991064E0E for ; Thu, 28 Jan 2021 18:13:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231442AbhA1SNv (ORCPT ); Thu, 28 Jan 2021 13:13:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:36018 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231518AbhA1SJD (ORCPT ); Thu, 28 Jan 2021 13:09:03 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id E451F64E07; Thu, 28 Jan 2021 18:08:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1611857301; bh=OGnQjiAgDA+88msfO4WmhcYEeZS/bNwPrFTaeyzswjA=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=ms8PfZju4tvgssHZjkeqp4UYoYnlnNZQzQBsbyOk6GlaqF2fx6nuxVOxfCog4zU/y SXH5QTCcEicGYmgE2RW2tuIzTyncvWwsPrcJ1YNWZG1wOsvoJTFg2tGekXm/aUq7XH jfmE/5P1xTJWBdccnG5fZYKGsSl8TI5PeXsz/QxY6SwCveATCnCZLUmX7iqRMGAXvs Wzl9hdegZSwG6+nbnzZNBJKf4Jt3d/L6E6LmEJWYZ67qTb0GiXEWe3ad6kxVvys/eJ dkWaDtomrh+KXG2fOVGeb3LvszPiYwRYP0Ft00sQ8nwUAqmnxBu6EjU8KCSqtjvDrA 99OGszTo768+A== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 929E63523769; Thu, 28 Jan 2021 10:08:21 -0800 (PST) Date: Thu, 28 Jan 2021 10:08:21 -0800 From: "Paul E. McKenney" To: Hillf Danton Cc: Xing Zhengjun , Oliver Sang , Peter Zijlstra , Lai Jiangshan , LKML , lkp@intel.com Subject: Re: [workqueue] d5bff968ea: WARNING:at_kernel/workqueue.c:#process_one_work Message-ID: <20210128180821.GA24510@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20210126073925.1962-1-hdanton@sina.com> <20210127092128.2299-1-hdanton@sina.com> <20210128090905.1596-1-hdanton@sina.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210128090905.1596-1-hdanton@sina.com> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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