From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755448Ab2AaW14 (ORCPT ); Tue, 31 Jan 2012 17:27:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:17998 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752916Ab2AaW1z (ORCPT ); Tue, 31 Jan 2012 17:27:55 -0500 Date: Tue, 31 Jan 2012 17:27:51 -0500 From: Don Zickus To: "Eric W. Biederman" Cc: x86@kernel.org, LKML , vgoyal@redhat.com, kexec-list Subject: Re: [PATCH] x86, kdump, ioapic: Fix kdump race with migrating irq Message-ID: <20120131222751.GE5650@redhat.com> References: <1328045114-4489-1-git-send-email-dzickus@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 31, 2012 at 02:08:29PM -0800, Eric W. Biederman wrote: > > The problem is that although kdump tries to shutdown minimal hardware, > > it still needs to disable the IO APIC. This requires spinlocks which > > may be held by another cpu. This other cpu is being held infinitely in > > an NMI context by kdump in order to serialize the crashing path. Instant > > deadlock. > > Can you test to see if kexec on panic still needs to disable the IO > APIC. Last I looked we were close if not all of the way there to not > needing to boot the kernel in pic mode? Ok, so you just blindly remove disable_IO_APIC from native_machine_crash_shutdown and re-run some panic tests on various machines? What about the disable_IO_APIC path in native_machine_shutdown? Also, where could I look to see if that work was done? Is that in the ioapic setup code? > > If we can skip the ioapic disable entirely we should be much more > robust. Agreed. Cheers, Don