Peter,

I got the warning

[   10.412023] 
[   10.412611] ======================================================
[   10.413014] [ INFO: possible circular locking dependency detected ]
[   10.413014] 3.6.0-rc4-00098-g7eaffe9 #402 Not tainted
[   10.413014] -------------------------------------------------------
[   10.413014] init/1 is trying to acquire lock:
[   10.413014]  (&p->pi_lock){-.-.-.}, at: [<ffffffff81088214>] task_work_add+0x28/0x82
[   10.413014] 
[   10.413014] but task is already holding lock:
[   10.413014]  (&rq->lock){-.-.-.}, at: [<ffffffff8109c6ea>] scheduler_tick+0x3f/0xec
[   10.413014] 
[   10.413014] which lock already depends on the new lock.
[   10.413014] 
[   10.413014] 

since commit:

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/numa
commit 4ae834f767c59b42cdf2a5077a18388525ba78b2
Author:     Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Mon Jul 16 11:22:09 2012 +0200
Commit:     Ingo Molnar <mingo@kernel.org>
CommitDate: Thu Sep 27 17:04:47 2012 +0200

    sched/numa: Implement NUMA home-node selection code

Thanks,
Fengguang