From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Lord Subject: Re: [PATCH 1/11] Add generic helpers for arch IPI function calls Date: Tue, 22 Apr 2008 19:12:45 -0400 Message-ID: <480E70ED.3030701@rtr.ca> References: <1208851058-8500-1-git-send-email-jens.axboe@oracle.com> <1208851058-8500-2-git-send-email-jens.axboe@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1208851058-8500-2-git-send-email-jens.axboe-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org> Sender: linux-arch-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: To: Jens Axboe Cc: linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, npiggin-l3A5Bk7waGM@public.gmane.org, torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org Jens, While you're in there, :) Could you perhaps fix this bug (below) if it still exists? > Date: Thu, 15 Nov 2007 12:07:48 -0500 > From: Mark Lord > To: Greg KH > Cc: Yasunori Goto , > Andrew Morton , > Alexey Dobriyan , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > Subject: Re: EIP is at device_shutdown+0x32/0x60 > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > Content-Transfer-Encoding: 7bit > Sender: linux-kernel-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org > > ... < snip > ... > > Greg, I don't know if this is relevant or not, > but x86 has bugs in the halt/reboot code for SMP. > > Specifically, in native_smp_send_stop() the code now uses > spin_trylock() to "lock" the shared call buffers, > but then ignores the result. > > This means that multiple CPUs can/will clobber each other > in that code. > > The second bug, is that this code does not wait for the > target CPUs to actually stop before it continues. > > This was the real cause of the failure-to-poweroff problems > I was having with 2.6.23, which we fixed by using CPU hotplug > to disable_nonboot_cpus() before the above code ever got run. > > Maybe it's related, maybe not. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rtr.ca ([76.10.145.34]:2073 "EHLO mail.rtr.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757592AbYDVXMl (ORCPT ); Tue, 22 Apr 2008 19:12:41 -0400 Message-ID: <480E70ED.3030701@rtr.ca> Date: Tue, 22 Apr 2008 19:12:45 -0400 From: Mark Lord MIME-Version: 1.0 Subject: Re: [PATCH 1/11] Add generic helpers for arch IPI function calls References: <1208851058-8500-1-git-send-email-jens.axboe@oracle.com> <1208851058-8500-2-git-send-email-jens.axboe@oracle.com> In-Reply-To: <1208851058-8500-2-git-send-email-jens.axboe@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Jens Axboe Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, npiggin@suse.de, torvalds@linux-foundation.org Message-ID: <20080422231245.Ekyh1UCWnxOdGzGaJnO20T0pMy3cYFOtqgQzTejhEIw@z> Jens, While you're in there, :) Could you perhaps fix this bug (below) if it still exists? > Date: Thu, 15 Nov 2007 12:07:48 -0500 > From: Mark Lord > To: Greg KH > Cc: Yasunori Goto , > Andrew Morton , > Alexey Dobriyan , linux-kernel@vger.kernel.org > Subject: Re: EIP is at device_shutdown+0x32/0x60 > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > Content-Transfer-Encoding: 7bit > Sender: linux-kernel-owner@vger.kernel.org > > ... < snip > ... > > Greg, I don't know if this is relevant or not, > but x86 has bugs in the halt/reboot code for SMP. > > Specifically, in native_smp_send_stop() the code now uses > spin_trylock() to "lock" the shared call buffers, > but then ignores the result. > > This means that multiple CPUs can/will clobber each other > in that code. > > The second bug, is that this code does not wait for the > target CPUs to actually stop before it continues. > > This was the real cause of the failure-to-poweroff problems > I was having with 2.6.23, which we fixed by using CPU hotplug > to disable_nonboot_cpus() before the above code ever got run. > > Maybe it's related, maybe not.