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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 1F4F9C33C99 for ; Tue, 7 Jan 2020 09:32:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E2A0120656 for ; Tue, 7 Jan 2020 09:32:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="3fMXxD/E" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727718AbgAGJco (ORCPT ); Tue, 7 Jan 2020 04:32:44 -0500 Received: from merlin.infradead.org ([205.233.59.134]:48582 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726485AbgAGJcn (ORCPT ); Tue, 7 Jan 2020 04:32:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=+gyT597CSUb3vTF8vtNS0ogoC3uLxUkJ9SR8FBD625M=; b=3fMXxD/EMYJ8d0ZJI1DssRuSO RXnlTsdLu1NFF8Hy2n2/aGvsL5i4auhHTXtmaZFF3W1+MCaqP3C7usTxowV3MEqN6kYcEOw8iM+x5 rmqGV91sqPXKjQmFXz+jdt00LIK4MINOqfG8QSyIlUcVWxiG1j+6c7dO6Gg3VMQmqHzqAcdVvRWJk t2NRTqdFAvUPQ9y5laCFGS5e7JNacKpgQmgvqJGPSf5AhvYm7P53UO/h7nhearv2pBIV/diZUCaFw zbwzZDCmhTIa0r9PPvDdGmXG0Gj/IgyAlnm/Gwt7L1V+IoaZ/EpE0E2EHBU7mUImDfw6fH5aNtyzj Rg+XNI0Hg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iolDk-0004hL-W6; Tue, 07 Jan 2020 09:32:17 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 28656304A59; Tue, 7 Jan 2020 10:30:42 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 91E3C2B48A33E; Tue, 7 Jan 2020 10:32:14 +0100 (CET) Date: Tue, 7 Jan 2020 10:32:14 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: Wei Li , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, huawei.libin@huawei.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched/debug: Reset watchdog on all CPUs while processing sysrq-t Message-ID: <20200107093214.GV2844@hirez.programming.kicks-ass.net> References: <20191226085224.48942-1-liwei391@huawei.com> <20200102144514.646df101@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200102144514.646df101@gandalf.local.home> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 02, 2020 at 02:45:14PM -0500, Steven Rostedt wrote: > On Thu, 26 Dec 2019 16:52:24 +0800 > Wei Li wrote: > > > Lengthy output of sysrq-t may take a lot of time on slow serial console > > with lots of processes and CPUs. > > > > So we need to reset NMI-watchdog to avoid spurious lockup messages, and > > we also reset softlockup watchdogs on all other CPUs since another CPU > > might be blocked waiting for us to process an IPI or stop_machine. > > Have you had this triggered? > > > > > Add to sysrq_sched_debug_show() as what we did in show_state_filter(). > > > > Signed-off-by: Wei Li > > --- > > kernel/sched/debug.c | 11 +++++++++-- > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c > > index f7e4579e746c..879d3ccf3806 100644 > > --- a/kernel/sched/debug.c > > +++ b/kernel/sched/debug.c > > @@ -751,9 +751,16 @@ void sysrq_sched_debug_show(void) > > int cpu; > > > > sched_debug_header(NULL); > > - for_each_online_cpu(cpu) > > + for_each_online_cpu(cpu) { > > + /* > > + * Need to reset softlockup watchdogs on all CPUs, because > > + * another CPU might be blocked waiting for us to process > > + * an IPI or stop_machine. > > + */ > > + touch_nmi_watchdog(); > > + touch_all_softlockup_watchdogs(); > > This doesn't seem to hurt to add, thus. > > Reviewed-by: Steven Rostedt (VMware) Thanks!