From patchwork Thu Aug 4 02:34:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Leizhen (ThunderTown)" X-Patchwork-Id: 12936051 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 9C74CC19F2A for ; Thu, 4 Aug 2022 02:34:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237699AbiHDCev (ORCPT ); Wed, 3 Aug 2022 22:34:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239180AbiHDCet (ORCPT ); Wed, 3 Aug 2022 22:34:49 -0400 Received: from szxga03-in.huawei.com (szxga03-in.huawei.com [45.249.212.189]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 632035FAF3; Wed, 3 Aug 2022 19:34:48 -0700 (PDT) Received: from dggpemm500024.china.huawei.com (unknown [172.30.72.56]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4Lyt7r0pv9zTgZC; Thu, 4 Aug 2022 10:33:28 +0800 (CST) Received: from dggpemm500006.china.huawei.com (7.185.36.236) by dggpemm500024.china.huawei.com (7.185.36.203) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 4 Aug 2022 10:34:46 +0800 Received: from thunder-town.china.huawei.com (10.174.178.55) by dggpemm500006.china.huawei.com (7.185.36.236) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 4 Aug 2022 10:34:45 +0800 From: Zhen Lei To: Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , "Mel Gorman" , Daniel Bristot de Oliveira , Valentin Schneider , , "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , "Josh Triplett" , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , CC: Zhen Lei Subject: [PATCH v4 1/2] sched/debug: Try trigger_single_cpu_backtrace(cpu) in dump_cpu_task() Date: Thu, 4 Aug 2022 10:34:19 +0800 Message-ID: <20220804023420.1663-2-thunder.leizhen@huawei.com> X-Mailer: git-send-email 2.26.0.windows.1 In-Reply-To: <20220804023420.1663-1-thunder.leizhen@huawei.com> References: <20220804023420.1663-1-thunder.leizhen@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.55] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500006.china.huawei.com (7.185.36.236) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Function trigger_all_cpu_backtrace() uses NMI to dump the stack traces of other CPU, it should actually be one of the ways to implement dump_cpu_task(). So try it first in dump_cpu_task(). At the same time, unnecessary duplicate code of upper-layer functions is eliminated. There is also a call to dump_cpu_task() in synchronize_rcu_expedited_wait(), which should also try to use NMI to dump the stack traces first. It is currently the result of this adjustment, so leave it unchanged. Signed-off-by: Zhen Lei --- kernel/rcu/tree_stall.h | 8 +++----- kernel/sched/core.c | 3 +++ kernel/smp.c | 3 +-- 3 files changed, 7 insertions(+), 7 deletions(-) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index a001e1e7a99269c..80749d257ac2f78 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -368,7 +368,7 @@ static void rcu_dump_cpu_stacks(void) if (rnp->qsmask & leaf_node_cpu_bit(rnp, cpu)) { if (cpu_is_offline(cpu)) pr_err("Offline CPU %d blocking current GP.\n", cpu); - else if (!trigger_single_cpu_backtrace(cpu)) + else dump_cpu_task(cpu); } raw_spin_unlock_irqrestore_rcu_node(rnp, flags); @@ -486,8 +486,7 @@ static void rcuc_kthread_dump(struct rcu_data *rdp) pr_err("%s kthread starved for %ld jiffies\n", rcuc->comm, j); sched_show_task(rcuc); - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); + dump_cpu_task(cpu); } /* Complain about starvation of grace-period kthread. */ @@ -515,8 +514,7 @@ static void rcu_check_gp_kthread_starvation(void) pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu); } else { pr_err("Stack dump where RCU GP kthread last ran:\n"); - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); + dump_cpu_task(cpu); } } wake_up_process(gpk); diff --git a/kernel/sched/core.c b/kernel/sched/core.c index df8fe433642fa30..0e82073020bf0d1 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -11145,6 +11145,9 @@ struct cgroup_subsys cpu_cgrp_subsys = { void dump_cpu_task(int cpu) { + if (trigger_single_cpu_backtrace(cpu)) + return; + pr_info("Task dump for CPU %d:\n", cpu); sched_show_task(cpu_curr(cpu)); } diff --git a/kernel/smp.c b/kernel/smp.c index dd215f439426449..56ca958364aebeb 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -370,8 +370,7 @@ static bool csd_lock_wait_toolong(struct __call_single_data *csd, u64 ts0, u64 * if (cpu >= 0) { if (static_branch_unlikely(&csdlock_debug_extended)) csd_lock_print_extended(csd, cpu); - if (!trigger_single_cpu_backtrace(cpu)) - dump_cpu_task(cpu); + dump_cpu_task(cpu); if (!cpu_cur_csd) { pr_alert("csd: Re-sending CSD lock (#%d) IPI from CPU#%02d to CPU#%02d\n", *bug_id, raw_smp_processor_id(), cpu); arch_send_call_function_single_ipi(cpu);