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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 56D6DC433E9 for ; Wed, 6 Jan 2021 09:54:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D3CD23104 for ; Wed, 6 Jan 2021 09:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727141AbhAFJx3 (ORCPT ); Wed, 6 Jan 2021 04:53:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42122 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726621AbhAFJx2 (ORCPT ); Wed, 6 Jan 2021 04:53:28 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17278C06134D for ; Wed, 6 Jan 2021 01:52:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=DVzL9L3/lzax/x2Pd3kTYJGUJQOk2k7Ej5ck80OWA1E=; b=0GOxVGj9g9vTZQpmChyHFzsW1+ nzbWD0vU9emv8ePOls6Iqg68LXee75oQVJqp3mcxW86XkLoyLzE6BSQMk9UTSHdOlEy5TFckdiqxp GjtKPd4ddIHjqhI0bmsB+/LkXWtohQJ63Jn5+s65d9udecJ7gyQLx2lvvGIIglV7HuyKX0L6DcZRd ij6IGxP58nZgfvdgjSV+o+F9G10zuozBu2EXQFKAYRh006t7rektAQv71zFu08WTcypzXW+XjnMeI sWITzgO2kh2grSt+2V2d0z3YOyXEFtYjHWB4BggyOmo4jkonTS2zEWwjRqg4Senr/9IzrUqQkf0k/ R9N4pQqA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kx5UJ-0003mR-1l; Wed, 06 Jan 2021 09:52:19 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id A57EC30015A; Wed, 6 Jan 2021 10:52:14 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 7706F2029F4C3; Wed, 6 Jan 2021 10:52:14 +0100 (CET) Date: Wed, 6 Jan 2021 10:52:14 +0100 From: Peter Zijlstra To: "Paul E. McKenney" Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, valentin.schneider@arm.com, bristot@redhat.com, frederic@kernel.org Subject: Re: lockdep splat in v5.11-rc1 involving console_sem and rq locks Message-ID: References: <20210105220115.GA27357@paulmck-ThinkPad-P72> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210105220115.GA27357@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 05, 2021 at 02:01:15PM -0800, Paul E. McKenney wrote: > Hello! > > The RUDE01 rcutorture scenario (and less often, the TASKS01 scenario) > results in occasional lockdep splats on v5.11-rc1 on x86. This failure > is probabalistic, sometimes happening as much as 30% of the time, but > sometimes happening quite a bit less frequently. (And yes, this did > result in a false bisection. Why do you ask?) The problem seems to > happen more frequently shortly after boot, so for fastest reproduction > run lots of 10-minute RUDE01 runs, which did eventually result in a > good bisection. (Yes, I did hammer the last good commit for awhile.) > > The first bad commit is 1cf12e08bc4d ("sched/hotplug: Consolidate task > migration on CPU unplug"). An example splat is shown below. > > Thoughts? The splat is because you hit a WARN, we're working on that. https://lkml.kernel.org/r/20201226025117.2770-1-jiangshanlai@gmail.com