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=-3.8 required=3.0 tests=BAYES_00, 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 92162C07E95 for ; Wed, 7 Jul 2021 17:32:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 76D3861C9A for ; Wed, 7 Jul 2021 17:32:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230288AbhGGRen (ORCPT ); Wed, 7 Jul 2021 13:34:43 -0400 Received: from foss.arm.com ([217.140.110.172]:41552 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230111AbhGGRem (ORCPT ); Wed, 7 Jul 2021 13:34:42 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 352871042; Wed, 7 Jul 2021 10:32:01 -0700 (PDT) Received: from e113632-lin (e113632-lin.cambridge.arm.com [10.1.194.46]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 15E4D3F694; Wed, 7 Jul 2021 10:31:59 -0700 (PDT) From: Valentin Schneider To: Guenter Roeck , Alexey Kardashevskiy , Frederic Weisbecker Cc: linux-kernel@vger.kernel.org, linux-tip-commits@vger.kernel.org, Ingo Molnar , Peter Zijlstra , x86@kernel.org Subject: Re: [tip: sched/core] sched/core: Initialize the idle task with preemption disabled In-Reply-To: References: <20210512094636.2958515-1-valentin.schneider@arm.com> <162081815405.29796.14574924529325899839.tip-bot2@tip-bot2> <20210706194456.GA1823793@roeck-us.net> <87fswr6lqv.mognet@arm.com> <20210707120305.GB115752@lothringen> <87czru727k.mognet@arm.com> <878s2i6uk2.mognet@arm.com> Date: Wed, 07 Jul 2021 18:31:55 +0100 Message-ID: <875yxm6nec.mognet@arm.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/07/21 09:35, Guenter Roeck wrote: > I think I have it. pseries_defconfig, and pseries emulation, > started with "-smp 2" and qemu-system-ppc64: > > [ 0.731644][ T1] smp: Bringing up secondary CPUs ...^M > [ 0.750546][ T0] BUG: scheduling while atomic: swapper/1/0/0x00000000^M > [ 0.752119][ T0] no locks held by swapper/1/0.^M > [ 0.752309][ T0] Modules linked in:^M > [ 0.752684][ T0] CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.13.0-11855-g77d34a4683b0 #1^M > [ 0.753197][ T0] Call Trace:^M > [ 0.753334][ T0] [c000000008737b20] [c0000000009f9b18] .dump_stack_lvl+0xa4/0x100 (unreliable)^M > [ 0.754224][ T0] [c000000008737bb0] [c000000000190ed0] .__schedule_bug+0xa0/0xe0^M > [ 0.754459][ T0] [c000000008737c30] [c000000001182518] .__schedule+0xc08/0xd90^M > [ 0.754738][ T0] [c000000008737d20] [c000000001182b8c] .schedule_idle+0x2c/0x60^M > [ 0.754945][ T0] [c000000008737d90] [c0000000001a48ec] .do_idle+0x29c/0x3c0^M > [ 0.755145][ T0] [c000000008737e60] [c0000000001a4df0] .cpu_startup_entry+0x30/0x40^M > [ 0.755403][ T0] [c000000008737ee0] [c00000000005ef10] .start_secondary+0x2c0/0x300^M > [ 0.755621][ T0] [c000000008737f90] [c00000000000d254] start_secondary_prolog+0x10/0x14^M > [ 0.764164][ T1] smp: Brought up 1 node, 2 CPUs^M > > Guenter Hmph, I was about to say I couldn't get that, but after cycling between different PREEMPT options I finally triggered it, so thanks for that! Same sha1 as yours, invocation is: qemu-system-ppc64 vmlinux -smp 2 -nographic -m 1024 -machine pseries,usb=off with pseries_defconfig + CONFIG_DEBUG_ATOMIC_SLEEP + CONFIG_PREEMPT_VOLUNTARY Now to dig!