Re: [BUG 2.6.27-rc1] find_busiest_group() LOCKUP

Peter Zijlstra
2010-11-11T13:04:05Z

On Thu, 2010-11-11 at 20:40 +0800, Wu Fengguang wrote:
> On Thu, Nov 11, 2010 at 08:36:18PM +0800, Peter Zijlstra wrote:
> > On Thu, 2010-11-11 at 18:06 +0800, Wu Fengguang wrote:
> > >
> > > I run into this kernel panic since 2.6.27-rc1. 2.6.36 boots OK.
> > > It's not yet fixed in 2.6.37-rc1-next-20101110. I can conveniently
> > > test any debug patches.
> > >
> > Happen to have a .config handy? I've never seen this..
>
> Here it is.

When I boot that .config and use the sched_debug boot param I get lots
of interesting stuff:

[ 1.187507] CPU0 attaching sched-domain:
[ 1.191431] domain 0: span 0-5 level MC
[ 1.195373] groups: 0 1 2 3 4 5
[ 1.198812] ERROR: parent span is not a superset of domain->span
[ 1.204813] domain 1: span 0-4,6 level CPU
[ 1.209100] ERROR: domain->groups does not contain CPU0
[ 1.214324] groups: 5 (cpu_power = 6144) 7 (cpu_power = 2048)
[ 1.220417] ERROR: groups don't span domain->span
[ 1.225118] domain 2: span 0-7 level NODE
[ 1.229403] groups:
[ 1.231868] ERROR: domain->cpu_power not set

Looks like something is totally screwy there and we start the
load-balancer before we actually build the sched domain tree or
something silly like that.

Will try and figure out how the heck that's happening, Ingo any clue?