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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 3C6FAC43381 for ; Thu, 28 Mar 2019 09:37:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 067852075E for ; Thu, 28 Mar 2019 09:37:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726540AbfC1JhE (ORCPT ); Thu, 28 Mar 2019 05:37:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53022 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726076AbfC1JhE (ORCPT ); Thu, 28 Mar 2019 05:37:04 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 07C5031688E3; Thu, 28 Mar 2019 09:37:04 +0000 (UTC) Received: from [10.36.112.59] (ovpn-112-59.ams2.redhat.com [10.36.112.59]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 018C71001DCC; Thu, 28 Mar 2019 09:36:57 +0000 (UTC) Subject: Re: [PATCH] watchdog: Respect watchdog cpumask on CPU hotplug To: Thomas Gleixner , Oleg Nesterov Cc: LKML , Peter Zijlstra , x86@kernel.org, Michael Ellerman , Nicholas Piggin , Don Zickus , Ricardo Neri References: <20190327151653.GA23811@redhat.com> From: Maxime Coquelin Message-ID: <34bbf93b-608f-b1ee-7b20-acb0def240a1@redhat.com> Date: Thu, 28 Mar 2019 10:36:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Thu, 28 Mar 2019 09:37:04 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/27/19 8:10 PM, Thomas Gleixner wrote: > On Wed, 27 Mar 2019, Oleg Nesterov wrote: >> On 03/26, Thomas Gleixner wrote: >>> >>> The rework of the watchdog core to use cpu_stop_work broke the watchdog >>> cpumask on CPU hotplug. >>> >>> The watchdog_enable/disable() functions are now called unconditionally from >>> the hotplug callback, i.e. even on CPUs which are not in the watchdog >>> cpumask. >>> >>> Only invoke them when the plugged CPU is in the watchdog cpumask. >> >> IIUC without this fix an NMI watchdog can too be enabled at boot time even >> if the initial watchdog_cpumask = housekeeping_cpumask(HK_FLAG_TIMER) doesn't >> include the plugged CPU. > > Yes. > >> And after that writing 0 to /proc/sys/kernel/nmi_watchdog clears >> NMI_WATCHDOG_ENABLED but this can't disable NMI watchdog's outside of >> watchdog_allowed_mask. > > Correct > >> So may be this can explain the problem reported by Maxime ? >> See https://lore.kernel.org/lkml/b99c5a25-a5fe-18dd-2f1d-bdd6834f03e5@redhat.com/ > > That looks so. I had a trial with your patch, and I can confirm it fixes my issue: Tested-by: Maxime Coquelin Thanks, Maxime > Thanks, > > tglx >