From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753314AbYIBOh4 (ORCPT ); Tue, 2 Sep 2008 10:37:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751364AbYIBOht (ORCPT ); Tue, 2 Sep 2008 10:37:49 -0400 Received: from one.firstfloor.org ([213.235.205.2]:53269 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751343AbYIBOhs (ORCPT ); Tue, 2 Sep 2008 10:37:48 -0400 Date: Tue, 2 Sep 2008 16:40:51 +0200 From: Andi Kleen To: Peter Zijlstra Cc: Andi Kleen , torvalds@osdl.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] [2/2] Don't complain about disabled irqs when the system has paniced Message-ID: <20080902144051.GM18288@one.firstfloor.org> References: <20080902349.573187695@firstfloor.org> <20080902134923.9A7EF3E6A01@basil.firstfloor.org> <1220365683.8609.58.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1220365683.8609.58.camel@twins> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Sep 02, 2008 at 04:28:03PM +0200, Peter Zijlstra wrote: > On Tue, 2008-09-02 at 15:49 +0200, Andi Kleen wrote: > > panic calls smp_send_stop which eventually calls smp_call_function_*. > > smp_call_function warns about disabled interrupts. But it's legal > > to call panic in this case. When this happens panic() prints > > several ugly backtraces. So don't check for disabled interrupts > > in panic state. > > While it might be legal for panic to be called from such contexts, I > understand those warnings are there to warn of deadlocks. > > So with the below patch you allow panic to deadlock if I understand > things correctly. Please describe the deadlock exactly. I don't think it can deadlock in this case. Besides do you prefer to not allow panic from interrupts/machine checks etc. anymore? -Andi