From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754310AbbAUDjp (ORCPT ); Tue, 20 Jan 2015 22:39:45 -0500 Received: from ozlabs.org ([103.22.144.67]:40997 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751853AbbAUDjo (ORCPT ); Tue, 20 Jan 2015 22:39:44 -0500 Date: Wed, 21 Jan 2015 14:39:42 +1100 From: Anton Blanchard To: Andrew Jones Cc: uobergfe@redhat.com, dzickus@redhat.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, Michael Ellerman Subject: Re: Confusing behaviour with /proc/sys/kernel/nmi_watchdog Message-ID: <20150121143942.1549e9c9@kryten> In-Reply-To: <20141105102645.GA3046@hawk.usersys.redhat.com> References: <20141105093420.1c7500d8@kryten> <20141105102645.GA3046@hawk.usersys.redhat.com> X-Mailer: Claws Mail 3.11.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew, > On Wed, Nov 05, 2014 at 09:34:20AM +1100, Anton Blanchard wrote: > > commit 9919e39a1738 ("kvm: ensure hard lockup detection is disabled > > by default") provided a way for the kernel to disable the hard > > lockup detector at runtime. > > > > I'm using it on ppc64 but notice some weird behaviour with the > > nmi_watchdog procfs variable. At boot, that the hard lockup > > detector appears to be enabled even when we disable it via > > watchdog_enable_hardlockup_detector(false): > > > > # cat /proc/sys/kernel/nmi_watchdog > > 1 > > > > I have to echo 0 to it then echo 1 again to enable it. > > > > Anton > > Hi Anton, > > Yes, the nmi watchdog proc variables are currently a bit > confusing. Uli has posted a series to clear all that up > though. Please see > > https://lkml.org/lkml/2014/10/17/340 Any progress on this? I'm rebasing our hardware NMI patch for ppc64 and notice the strange behaviour is still in mainline. Anton