From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754122AbXJJLUo (ORCPT ); Wed, 10 Oct 2007 07:20:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752142AbXJJLUf (ORCPT ); Wed, 10 Oct 2007 07:20:35 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:38672 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751342AbXJJLUe (ORCPT ); Wed, 10 Oct 2007 07:20:34 -0400 From: "Rafael J. Wysocki" To: Milton Miller Subject: Re: [stable] [patch 09/12] Fix SMP poweroff hangs Date: Wed, 10 Oct 2007 13:35:48 +0200 User-Agent: KMail/1.9.5 Cc: Linus Torvalds , Mark Lord , linux-kernel@vger.kernel.org, Thomas Gleixner , Andrew Morton , Greg Kroah-Hartman , linux-pm@lists.linux-foundation.org, Len Brown References: <20071008180406.052382073@mini.kroah.org> <200710101006.l9AA657g083900@sullivan.realtime.net> In-Reply-To: <200710101006.l9AA657g083900@sullivan.realtime.net> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200710101335.49866.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wednesday, 10 October 2007 12:06, Milton Miller wrote: > > On Tue, Oct 9 2007 Thomas Gleixner wrote: > >On Tue, 9 Oct 2007, Linus Torvalds wrote: > >>On Wed, 10 Oct 2007, Thomas Gleixner wrote: > >>> > >>> Wrapping it into a #ifdef CONFIG_X86 would be sufficient. > >> > >> Well, the ppc oops seems to be a ppc bug regardless. > >> > >> If CPU_HOTPLUG isn't defined, the thing does nothing. And if it is > >> defined, I don't see why/how ppc can validly oops. So I think the first > >> thing to do is to try to figure out why it oopses, not to disable it for > >> ppc. > > > >Fair enough. OTOH for the affected PPC users it's a regression and that's > >what I'm concerned of. > > > >tglx > > I agree this exposes a ppc arch bug (and the reason has been diagnosed), > but might not other archs have similar problems? The patch ties > power-off code to suspend and hibernate cpu hotplug code. > > Why not put this ACPI requirement in the ACPI code? There is already > a hook called at the same place this function was called that is only > used for power off. IMO this is a good idea. > Also, the code is compiled for CONFIG_PM_SLEEP_SMP, which is not > CONFIG_HOTPLUG_CPU, it requires the selection of either CONFIG_HIBERNATION > or CONFIG_SUSPEND. I confirmed that both of these can be disabled > on i386 without disabling acpi. In such a kernel the existing patch > is insufficient. Well, it's a known problem with this patch. However, to resolve it we'd need to make ACPI select the CPU hotplug on SMP, just like PM_SLEEP. IOW, we should have a rule that if (ACPI || PM_SLEEP) && SMP, then the CPU hotplug is selected. Greetings, Rafael > drivers/acpi/sleep/main.c | 2 ++ > kernel/sys.c | 1 - > 2 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/drivers/acpi/sleep/main.c b/drivers/acpi/sleep/main.c > index 2cbb9aa..79589bd 100644 > --- a/drivers/acpi/sleep/main.c > +++ b/drivers/acpi/sleep/main.c > @@ -15,6 +15,7 @@ > #include > #include > #include > +#include > > #include > > @@ -382,6 +383,7 @@ static void acpi_power_off_prepare(void) > { > /* Prepare to power off the system */ > acpi_sleep_prepare(ACPI_STATE_S5); > + disable_nonboot_cpus(); > } > > static void acpi_power_off(void) > diff --git a/kernel/sys.c b/kernel/sys.c > index 8ae2e63..138f5c8 100644 > --- a/kernel/sys.c > +++ b/kernel/sys.c > @@ -879,7 +879,6 @@ void kernel_power_off(void) > kernel_shutdown_prepare(SYSTEM_POWER_OFF); > if (pm_power_off_prepare) > pm_power_off_prepare(); > - disable_nonboot_cpus(); > sysdev_shutdown(); > printk(KERN_EMERG "Power down.\n"); > machine_power_off(); > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > > -- "Premature optimization is the root of all evil." - Donald Knuth