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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 E651EC433E0 for ; Fri, 19 Feb 2021 08:37:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 943A264EC0 for ; Fri, 19 Feb 2021 08:37:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229599AbhBSIh1 (ORCPT ); Fri, 19 Feb 2021 03:37:27 -0500 Received: from inva021.nxp.com ([92.121.34.21]:49880 "EHLO inva021.nxp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229639AbhBSIhZ (ORCPT ); Fri, 19 Feb 2021 03:37:25 -0500 Received: from inva021.nxp.com (localhost [127.0.0.1]) by inva021.eu-rdc02.nxp.com (Postfix) with ESMTP id ED351200614; Fri, 19 Feb 2021 09:36:33 +0100 (CET) Received: from invc005.ap-rdc01.nxp.com (invc005.ap-rdc01.nxp.com [165.114.16.14]) by inva021.eu-rdc02.nxp.com (Postfix) with ESMTP id 1A7F420061E; Fri, 19 Feb 2021 09:36:29 +0100 (CET) Received: from localhost.localdomain (mega.ap.freescale.net [10.192.208.232]) by invc005.ap-rdc01.nxp.com (Postfix) with ESMTP id 723C1402D2; Fri, 19 Feb 2021 09:36:22 +0100 (CET) From: Ran Wang To: Sebastian Siewior , Thomas Gleixner Cc: Jiafei Pan , linux-rt-users@vger.kernel.org, Ingo Molnar , Peter Zijlstra , "Rafael J . Wysocki" , Viresh Kumar , Ran Wang Subject: [PATCH] rt: cpufreq: Fix cpu hotplug hang Date: Fri, 19 Feb 2021 16:44:20 +0800 Message-Id: <20210219084420.23379-1-ran.wang_1@nxp.com> X-Mailer: git-send-email 2.17.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Virus-Scanned: ClamAV using ClamSMTP Precedence: bulk List-ID: X-Mailing-List: linux-rt-users@vger.kernel.org When selecting PREEMPT_RT, cpufreq_driver->stop_cpu(policy) might got stuck due to irq_work_sync() pending for work on lazy_list. That’s because lazy_list may have no chance to be served in softirq context sometimes. Below is one of scenarios that was captured: ... ret_from_fork kthread smpboot_thread_fn cpuhp_thread_fun cpuhp_invoke_callback: state: 193 cpuhp_cpufreq_online cpufreq_online cpufreq_driver->stop_cpu(policy); cpufreq_dbs_governor_stop sugov_stop // kernel/sched/cpufreq_schedutil.c irq_work_sync(&sg_policy->irq_work); This is observed on LX2160ARDB (16 A72 cores) with cpufreq governor of ‘schedutil’ or ‘ondemand’. Configure related irqwork to run on raw-irq context could fix this. Signed-off-by: Ran Wang --- drivers/cpufreq/cpufreq_governor.c | 2 +- kernel/sched/cpufreq_schedutil.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c index 63f7c219062b..731a7b1434df 100644 --- a/drivers/cpufreq/cpufreq_governor.c +++ b/drivers/cpufreq/cpufreq_governor.c @@ -360,7 +360,7 @@ static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *poli policy_dbs->policy = policy; mutex_init(&policy_dbs->update_mutex); atomic_set(&policy_dbs->work_count, 0); - init_irq_work(&policy_dbs->irq_work, dbs_irq_work); + policy_dbs->irq_work = IRQ_WORK_INIT_HARD(dbs_irq_work); INIT_WORK(&policy_dbs->work, dbs_work_handler); /* Set policy_dbs for all CPUs, online+offline */ diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c index 6931f0cdeb80..054a01ef4f57 100644 --- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -719,7 +719,7 @@ static int sugov_kthread_create(struct sugov_policy *sg_policy) sg_policy->thread = thread; kthread_bind_mask(thread, policy->related_cpus); - init_irq_work(&sg_policy->irq_work, sugov_irq_work); + sg_policy->irq_work = IRQ_WORK_INIT_HARD(sugov_irq_work); mutex_init(&sg_policy->work_lock); wake_up_process(thread); -- 2.25.1