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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 8EBB9C2D0E4 for ; Tue, 17 Nov 2020 13:35:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3E6C72467D for ; Tue, 17 Nov 2020 13:35:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="KNfNpvNu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732461AbgKQNfV (ORCPT ); Tue, 17 Nov 2020 08:35:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:45932 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732455AbgKQNfT (ORCPT ); Tue, 17 Nov 2020 08:35:19 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id AF7BC2466D; Tue, 17 Nov 2020 13:35:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605620119; bh=6DIxz/ib5e4NY8x17EduEG3JMHRG1WPKsMLGX1UO9Bg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KNfNpvNup/pUy6OB6Wayy4WpzHtEKnTxdVZNzZZXFr8JTlsFYN+iDu483sWmlo7GR YG/E9uGGF2VZZ61tcQTMbDRsCIwaasDBrF/FapfSvp61cPRahqF+44VEKCHTZm3lzn azh2lIDNoAs/nI1uBIZPlTL+v6OullmABPT6ISo0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qian Cai , "Paul E. McKenney" , Heiko Carstens , Sasha Levin Subject: [PATCH 5.9 113/255] s390/smp: move rcu_cpu_starting() earlier Date: Tue, 17 Nov 2020 14:04:13 +0100 Message-Id: <20201117122144.446679032@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201117122138.925150709@linuxfoundation.org> References: <20201117122138.925150709@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Qian Cai [ Upstream commit de5d9dae150ca1c1b5c7676711a9ca139d1a8dec ] The call to rcu_cpu_starting() in smp_init_secondary() is not early enough in the CPU-hotplug onlining process, which results in lockdep splats as follows: WARNING: suspicious RCU usage ----------------------------- kernel/locking/lockdep.c:3497 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. Call Trace: show_stack+0x158/0x1f0 dump_stack+0x1f2/0x238 __lock_acquire+0x2640/0x4dd0 lock_acquire+0x3a8/0xd08 _raw_spin_lock_irqsave+0xc0/0xf0 clockevents_register_device+0xa8/0x528 init_cpu_timer+0x33e/0x468 smp_init_secondary+0x11a/0x328 smp_start_secondary+0x82/0x88 This is avoided by moving the call to rcu_cpu_starting up near the beginning of the smp_init_secondary() function. Note that the raw_smp_processor_id() is required in order to avoid calling into lockdep before RCU has declared the CPU to be watched for readers. Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/ Signed-off-by: Qian Cai Acked-by: Paul E. McKenney Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- arch/s390/kernel/smp.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 85700bd85f98d..3b4c3140c18e7 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -855,13 +855,14 @@ void __init smp_detect_cpus(void) static void smp_init_secondary(void) { - int cpu = smp_processor_id(); + int cpu = raw_smp_processor_id(); S390_lowcore.last_update_clock = get_tod_clock(); restore_access_regs(S390_lowcore.access_regs_save_area); set_cpu_flag(CIF_ASCE_PRIMARY); set_cpu_flag(CIF_ASCE_SECONDARY); cpu_init(); + rcu_cpu_starting(cpu); preempt_disable(); init_cpu_timer(); vtime_init(); -- 2.27.0