Willy Tarreau wrote:
> On Sat, Dec 19, 2009 at 04:10:49PM +0100, Holger Hoffstaette wrote:
>> After updating to 2.6.32.2 last night (using same config from .32.1) I
>> noticed that "halt" now trips during shutdown and won't power the
>> machine down any longer. This happens reproducibly on two completely
>> different machines, so it looks like a generic problem and regression,
>> since it did not happen in .32.1. Note that "reboot" works as expected -
>> only "halt" crashes.
> 
> I have it working fine here. So your config helps to reproduce the issue.
> Care to post it ?

Attached, if it matters. However I managed to find some time with a spare
machine and always wanted to try bisect, so that's what I did - apparently
successfully:

root>git bisect bad
37ed2d7007a65874850f3e357c095806c3756330 is the first bad commit
commit 37ed2d7007a65874850f3e357c095806c3756330
Author: Mike Galbraith <efault@gmx.de>
Date:   Wed Nov 4 17:53:50 2009 +0100

    sched: Rate-limit newidle

    commit 1b9508f6831e10d53256825de8904caa22d1ca2c upstream.

    Rate limit newidle to migration_cost. It's a win for all
    stages of sysbench oltp tests.

    Signed-off-by: Mike Galbraith <efault@gmx.de>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    LKML-Reference: <new-submission>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

aka:
http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.32.y.git;a=commit;h=37ed2d7007a65874850f3e357c095806c3756330

My understanding is that this was supposed to be a performance fix for the
CPU scheduler. Maybe it collides with CPU shutdown on halt?

Holger