From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934054AbXC0RfW (ORCPT ); Tue, 27 Mar 2007 13:35:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934062AbXC0RfV (ORCPT ); Tue, 27 Mar 2007 13:35:21 -0400 Received: from mx1.redhat.com ([66.187.233.31]:60555 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934059AbXC0RfU (ORCPT ); Tue, 27 Mar 2007 13:35:20 -0400 Message-ID: <460955CC.70006@redhat.com> Date: Tue, 27 Mar 2007 13:35:08 -0400 From: Prarit Bhargava User-Agent: Thunderbird 1.5.0.10 (X11/20070221) MIME-Version: 1.0 To: Jeremy Fitzhardinge CC: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, clalance@redhat.com, mingo@redhat.com, davej@redhat.com, Thilo.Cestonaro.external@fujitsu-siemens.com Subject: Re: [PATCH]: Fix bogus softlockup warning with sysrq-t References: <20070315132247.11291.28827.sendpatchset@prarit.boston.redhat.com> <4608AF01.4060804@goop.org> <460902CF.1030202@redhat.com> <46094A70.9080901@goop.org> In-Reply-To: <46094A70.9080901@goop.org> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jeremy Fitzhardinge wrote: > > diff -r 4c81d8cafb67 drivers/char/sysrq.c > --- a/drivers/char/sysrq.c Tue Mar 27 01:16:07 2007 -0700 > +++ b/drivers/char/sysrq.c Tue Mar 27 01:18:05 2007 -0700 > @@ -408,6 +408,8 @@ void __handle_sysrq(int key, struct tty_ > int i; > unsigned long flags; > > + softlockup_global_disable(); > + > spin_lock_irqsave(&sysrq_key_table_lock, flags); > orig_log_level = console_loglevel; > console_loglevel = 7; > @@ -445,6 +447,8 @@ void __handle_sysrq(int key, struct tty_ > console_loglevel = orig_log_level; > } > spin_unlock_irqrestore(&sysrq_key_table_lock, flags); > + > + softlockup_global_enable(); > } > > I wonder if that's too strong of a fix. It's only the sysrq-t case that is the problem. AFAIK, none of the other sysrq-t operations hold the tasklist_lock for a long time. I'd move these around show_state. P.