Re: regression in 2.6.23-rc8 - power off failed

[Mark Lord <lkml@rtr.ca>]

Wolfgang Erig wrote:
> On Sat, Sep 29, 2007 at 01:30:33AM -0700, H. Peter Anvin wrote:
> > Wolfgang Erig wrote:
> > > Both are bad.
> > > Two different systems and two different bisections.
> > > I sent the last step of each.
> > > > > $ git bisect good 
> > > > > Bisecting: 0 revisions left to test after this 
> > > > > [626073132b381684c4983e0d911e9aceb32e2cbc] Assembly header and main routine for new x86 setup code 
> > > > OK, so which one is the bad one?
> > > This problem (no power off) persists after pull some minutes ago.
> > > Sorry for the confusion.
> > I believe there must have been something wrong here (possibly
> > inconsistent experiments?)  This checkin has *zero code changes* from
> > the previous one (and next one) -- the kernel should have been binarily
> > identical to the previous one.  The code introduced in this checkin
> > doesn't even get compiled until two checkins later,
> > 4fd06960f120e02e9abc802a09f9511c400042a5.
>
> I have done two bisections simultanously and it was late at night.
> I start again with a fresh tree and better controlled experiments.

If this is an SMP system, then you could just be getting random results,
depending upon which CPU is attempting the poweroff.

I have a newish patch in Andrew's tree now to fix SMP poweroff
(has been broken forever), reproduced here below in case you missed it.

* * *
We need to disable all CPUs other than the boot CPU (usually 0)
before attempting to power-off modern SMP machines.
This fixes the hang-on-poweroff issue on my MythTV SMP box,
and also on Thomas Gleixner's new toybox.

Signed-off-by: Mark Lord <mlord@pobox.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
---

--- linux/kernel/sys.c.orig	2007-09-13 09:49:11.000000000 -0400
+++ linux/kernel/sys.c	2007-09-28 15:48:54.000000000 -0400
@@ -32,6 +32,7 @@
#include <linux/getcpu.h>
#include <linux/task_io_accounting_ops.h>
#include <linux/seccomp.h>
+#include <linux/cpu.h>

#include <linux/compat.h>
#include <linux/syscalls.h>
@@ -878,6 +879,7 @@
	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();
-
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