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=-7.7 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 D9955C433E6 for ; Thu, 14 Jan 2021 15:22:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A1E2323B28 for ; Thu, 14 Jan 2021 15:22:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728801AbhANPWs (ORCPT ); Thu, 14 Jan 2021 10:22:48 -0500 Received: from mail.kernel.org ([198.145.29.99]:35116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726578AbhANPWs (ORCPT ); Thu, 14 Jan 2021 10:22:48 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 65EC023B28; Thu, 14 Jan 2021 15:22:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1610637727; bh=lP9Rg5ur/WccpQs9eF+9HiBwQ4afk3nrnViDH0nFIbA=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=UuLzFEoP1jUWXxWv4BiBEertVhHHdUIsdWQXnjEhubFlWexxSjrqkGI+olnI8DPwU RXJ71IEsNP0wg7jr4hdtg118UDQAXPbmizxfY+Rtu9nbYaufgyfH+hPmPVSXuUCd/u JpiimImRv+C5k4dFH04G4YQeUCuTcGmwS4286OlxTmLXreg1YlLhYIqbvQFJpV481c skZS6MtdajiBcc6truOCViwkaSmgIZy6QHiRQYAIKCKB87Om+qjW4cr8dho7BgnGjA N+4JbewwUVRK2tkRpWwQ8R13D1pMdWufZqqBSlXvnia8CHdnze1Uj6ve1peBbTjZVZ B1ggHV5A457MA== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 3812435225DC; Thu, 14 Jan 2021 07:22:07 -0800 (PST) Date: Thu, 14 Jan 2021 07:22:07 -0800 From: "Paul E. McKenney" To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, peterz@infradead.org, mingo@kernel.org, tglx@linutronix.de, jiangshanlai@gmail.com, cai@redhat.com, vincent.donnefort@arm.com, decui@microsoft.com, vincent.guittot@linaro.org, rostedt@goodmis.org, tj@kernel.org Subject: Re: [PATCH] sched/core: Print out straggler tasks in sched_cpu_dying() Message-ID: <20210114152207.GI2743@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20210113183141.11974-1-valentin.schneider@arm.com> <20210113220244.GC2743@paulmck-ThinkPad-P72> <20210114003613.GD2743@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 14, 2021 at 10:37:35AM +0000, Valentin Schneider wrote: > On 13/01/21 16:36, Paul E. McKenney wrote: > > On Thu, Jan 14, 2021 at 12:15:24AM +0000, Valentin Schneider wrote: > >> On 13/01/21 14:02, Paul E. McKenney wrote: > >> Thanks for giving it a spin! I think with the current series (either > >> Lai's or Peter's) sched_cpu_dying() should go smoothly, but you never > >> know. > > > > I was running the patch set having one of Lai's and three of Peter's, > > which sounds like Peter's. > > That's how I was seeing it :) If someone can identify Lai's series to me, I would be happy to give it a try as well. All I see are workqueue-specific patches and patches contributing to the discussion of possible fixes to the splats from Peter's series. (I figured that I would wait for the discussion to converge a bit.) > > If I understand which series is which, > > Peter's has the advantage of not requiring rcutorture changes. ;-) > > > >> > However, it did produce the following new-to-me splat, which will > >> > hopefully be of some help. > >> > > >> > Thanx, Paul > >> > > >> > ------------------------------------------------------------------------ > >> > > >> > WARNING: CPU: 2 PID: 23 at kernel/kthread.c:508 kthread_set_per_cpu+0x3b/0x50 > >> > >> Aha, so that's that warning I was expecting to see [1]. > >> Did you also get the process_one_work() one? > > > > Yes. Of 112 one-hour runs, there were five process_one_work() splats > > and two kthread_set_per_cpu() splats. Each splat-ridden run had exactly > > one splat. > > I was expecting to see both in one run, so am still somewhat confused. Well, if we weren't confused in some way or another, the bug would not exist, so I will count becoming aware of confusion as a step forward. ;-) Thanx, Paul