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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 273C0C46467 for ; Mon, 16 Jan 2023 18:17:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232556AbjAPSRE (ORCPT ); Mon, 16 Jan 2023 13:17:04 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232878AbjAPSQG (ORCPT ); Mon, 16 Jan 2023 13:16:06 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F11E2CDF6 for ; Mon, 16 Jan 2023 10:03:19 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 89C8BB810B0 for ; Mon, 16 Jan 2023 18:03:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1FFF6C433EF; Mon, 16 Jan 2023 18:03:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673892197; bh=NFPsiNZYg4maqAu/06zPYzHMj1FCUnnXkDYxZ2MpxEc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=K2daj6F/sWXHBc1T1hyseidPZRFaUN+hNWgOF1yR1ig6Z18wiiUFRdGTLxVQ2/c2F AC6LZzwCMgPaodpgyYdm/TH5jOup/AwTzwH7SwRypI51Mp0kOPy+q4DmKWhybLqPOM wIIob3R4jm70BkM5/MF/9S0WwV/YjBcm5OMRk/v8JZXk+r3flIjMYdP9oEUnY6hdpo uCNSDBR8fkVlRI/7HNJ1M9t+LVaNzMWEyK/4i+r8YTretW0lJqLYf1Th0pIN5xQFxN 4CNkEm2tGzv0W4thafzYbaj2evi26/dhNGc2aIb5d5SG3kG5G6IMOOEMzMp2UHF2Eg FLXCd+q9ucmbg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1pHTpC-002ELD-RM; Mon, 16 Jan 2023 18:03:14 +0000 Date: Mon, 16 Jan 2023 18:03:14 +0000 Message-ID: <864jsqnyql.wl-maz@kernel.org> From: Marc Zyngier To: Joel Fernandes Cc: "moderated list:ARM/STM32 ARCHITECTURE" , Will Deacon , Mark Rutland , Catalin Marinas , rcu , "Paul E. McKenney" Subject: Re: arm64 torture test hotplug failures (offlining causes -EBUSY) In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/28.2 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: joel@joelfernandes.org, linux-arm-kernel@lists.infradead.org, will@kernel.org, mark.rutland@arm.com, catalin.marinas@arm.com, rcu@vger.kernel.org, paulmck@kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Hi Joel, On Mon, 16 Jan 2023 17:03:31 +0000, Joel Fernandes wrote: > > Hello, > I am seeing -EBUSY returned a lot during torture_onoff() when running > rcutorture on arm64. This causes hotplug failure 30% of the time. I am > also seeing this in 6.1-rc kernels. I believe see this only for CPU0. > > This causes warnings in torture tests: > [ 217.582290] rcu-torture:torture_onoff task: offline 0 failed: errno -16 > [ 221.866362] rcu-torture:torture_onoff task: offline 0 failed: errno -16 > > Full kernel log here: > http://box.joelfernandes.org:9080/job/rcutorture_stable_arm/job/linux-5.15.y/7/artifact/tools/testing/selftests/rcutorture/res/2023.01.15-14.51.11/TREE04/console.log > > Any ideas on why this is happening and only for CPU 0 (presumably the > boot CPU)? I'd personally need these warnings to go away for my tests > as this causes rcutorture's tests to not cleanly pass for me. It > appears remove_cpu() -> device_offline() is what returns the error. I've taken your kernel for a ride as a KVM guest (probably similar to what you are doing), and saw the same thing (CPU0 not offlining): [ 64.555845] Detected VIPT I-cache on CPU4 [ 64.556146] GICv3: CPU4: found redistributor 4 region 0:0x000000003ff70000 [ 64.556689] CPU4: Booted secondary processor 0x0000000004 [0x612f0290] [ 69.823670] rcu-torture:torture_onoff task: offline 0 failed: errno -16 [ 73.991960] psci: CPU7 killed (polled 0 ms) [ 74.239626] rcu-torture: rcu_torture_read_exit: Start of episode [ 74.243863] rcu-torture: rcu_torture_read_exit: End of episode I then tried v6.2-rc4 with defconfig + RCU_TORTURE and your command line, and CPU0 does seem to hotplug off correctly: [ 47.217109] psci: CPU3 killed (polled 0 ms) [ 52.241009] Detected VIPT I-cache on CPU3 [ 52.241227] cacheinfo: Unable to detect cache hierarchy for CPU 3 [ 52.241481] GICv3: CPU3: found redistributor 3 region 0:0x000000003ff50000 [ 52.241849] CPU3: Booted secondary processor 0x0000000003 [0x612f0290] [ 56.337011] psci: CPU0 killed (polled 0 ms) [...] [ 121.090339] rcu-torture: Free-Block Circulation: 922 920 919 918 917 916 914 913 912 911 0 [ 125.574311] Detected VIPT I-cache on CPU0 [ 125.574557] cacheinfo: Unable to detect cache hierarchy for CPU 0 [ 125.574901] GICv3: CPU0: found redistributor 0 region 0:0x000000003fef0000 [ 125.575322] CPU0: Booted secondary processor 0x0000000000 [0x612f0290] [ 130.176893] rcu-torture: rcu_torture_read_exit: Start of episode [ 130.317001] psci: CPU0 killed (polled 0 ms) [...] [ 225.588999] Detected VIPT I-cache on CPU0 [ 225.589224] cacheinfo: Unable to detect cache hierarchy for CPU 0 [ 225.589535] GICv3: CPU0: found redistributor 0 region 0:0x000000003fef0000 [ 225.589946] CPU0: Booted secondary processor 0x0000000000 [0x612f0290] No such error is being reported. Is there anything special in your config that would help triggering this with the current tip of tree? Thanks, M. -- Without deviation from the norm, progress is not possible.