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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 045F2C2D0A3 for ; Fri, 6 Nov 2020 11:10:43 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7EF1B20735 for ; Fri, 6 Nov 2020 11:10:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Te41SDg+"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="kKAnkjgF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7EF1B20735 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Transfer-Encoding: Content-Type:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To:Message-Id:Date: Subject:To:From:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=96hzjg1ZYIfoaeRcTiv24GtC8BotDyCtjW6VqKfGqK0=; b=Te41SDg+QP+vKG607LTVWyXHw VQnvwtXdFPG1x/t9EPHGljYPlY4lHUXKz0lGjQVx8Bzxj+el2q16JNsmUNos2ByX+cUr74i704LVo gWQSpL2krIYk/dn2JwCHXjNkhydIVzMoGYNrFFDDpmObj9uduUhcOQPhel5ALQKCVTVmEctrsvQk3 OQkN33D4KYlbgE1IsrdiHbsJmqHrw1XHvl6REuaaYLBBrK7eJXuosmJRQ1EFMqQkzEdbfwlovXkyI QqRnvdSyJB50rHIM74EJitMHlGFB8C6EEOkCmepMuVxys0vqv0+qbNrmDtP1+2LxFdNyK0227G03g nQ6RLghgQ==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kaz6U-0004XX-PZ; Fri, 06 Nov 2020 10:36:22 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kaz6L-0004VQ-B2 for linux-arm-kernel@lists.infradead.org; Fri, 06 Nov 2020 10:36:16 +0000 Received: from localhost.localdomain (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 30CAE22210; Fri, 6 Nov 2020 10:36:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604658972; bh=/vTTl0pkJzaD4ZRo9JTNRTkKRqgmwGOEBRJhwSNSILM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kKAnkjgF3YVzWr1IFN+8GQyhF1yJskb6G5SJjSwypMqm4mF0fi7nEHqiYLztUO23P IfMfpMD1Cfk3YcrHhnxjVWyhzAworBF7JBYFeIJAgxl8s6wroSCTjaYNCS5+6Apllz xHpwdMasrSMdGE6THyLkzl2GnB3MuB2oa5vj05og= From: Will Deacon To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/2] arm64: smp: Tell RCU about CPUs that fail to come online Date: Fri, 6 Nov 2020 10:36:02 +0000 Message-Id: <20201106103602.9849-3-will@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20201106103602.9849-1-will@kernel.org> References: <20201106103602.9849-1-will@kernel.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201106_053613_484285_8E240883 X-CRM114-Status: GOOD ( 15.65 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Paul E. McKenney" , Qian Cai , kernel-team@android.com, linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Commit ce3d31ad3cac ("arm64/smp: Move rcu_cpu_starting() earlier") ensured that RCU is informed early about incoming CPUs that might end up calling into printk() before they are online. However, if such a CPU fails the early CPU feature compatibility checks in check_local_cpu_capabilities(), then it will be powered off or parked without informing RCU, leading to an endless stream of stalls: | rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: | rcu: 2-O...: (0 ticks this GP) idle=002/1/0x4000000000000000 softirq=0/0 fqs=2593 | (detected by 0, t=5252 jiffies, g=9317, q=136) | Task dump for CPU 2: | task:swapper/2 state:R running task stack: 0 pid: 0 ppid: 1 flags:0x00000028 | Call trace: | ret_from_fork+0x0/0x30 Ensure that the dying CPU invokes rcu_report_dead() prior to being powered off or parked. Cc: Qian Cai Cc: "Paul E. McKenney" Suggested-by: Qian Cai Signed-off-by: Will Deacon --- arch/arm64/kernel/smp.c | 1 + kernel/rcu/tree.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 09c96f57818c..18e9727d3f64 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -413,6 +413,7 @@ void cpu_die_early(void) /* Mark this CPU absent */ set_cpu_present(cpu, 0); + rcu_report_dead(cpu); if (IS_ENABLED(CONFIG_HOTPLUG_CPU)) { update_cpu_boot_status(CPU_KILL_ME); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 2a52f42f64b6..bd04b09b84b3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4077,7 +4077,6 @@ void rcu_cpu_starting(unsigned int cpu) smp_mb(); /* Ensure RCU read-side usage follows above initialization. */ } -#ifdef CONFIG_HOTPLUG_CPU /* * The outgoing function has no further need of RCU, so remove it from * the rcu_node tree's ->qsmaskinitnext bit masks. @@ -4117,6 +4116,7 @@ void rcu_report_dead(unsigned int cpu) rdp->cpu_started = false; } +#ifdef CONFIG_HOTPLUG_CPU /* * The outgoing CPU has just passed through the dying-idle state, and we * are being invoked from the CPU that was IPIed to continue the offline -- 2.29.1.341.ge80a0c044ae-goog _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel