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

[Peter Zijlstra <peterz@infradead.org>]

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?