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Date: Thu, 20 Sep 2012 14:58:01 +0200
From: Borislav Petkov <bp@alien8.de>
To: Michael Wang <wangyun@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
        Akinobu Mita <akinobu.mita@gmail.com>,
        lkml <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>
Subject: Re: kernel BUG at kernel/sched/core.c:1465!
Message-ID: <20120920125801.GA15045@x1.osrc.amd.com>
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	Michael Wang <wangyun@linux.vnet.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Akinobu Mita <akinobu.mita@gmail.com>,
	lkml <linux-kernel@vger.kernel.org>, Tejun Heo <tj@kernel.org>
References: <20120919091230.GA25576@liondog.tnic>
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On Thu, Sep 20, 2012 at 02:38:47PM +0800, Michael Wang wrote:
> Could you please try below patch and see whether the new WARNING
> appear or not?
>
> And cc Tejun Heo <tj@kernel.org> since wq_worker_sleeping() doesn't
> work as it's introduced...

Ok, now that you mentioned workqueues, I remember the powernow-k8
workaround from Tejun a couple of days ago and looking at Linus' tree
from today, he actually merged a fix for exactly that:

commit c5c473e29c641380aef4a9d1f9c39de49219980f
Merge: 925a6f0bf8bd 6889125b8b4e
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed Sep 19 11:00:07 2012 -0700

    Merge branch 'for-3.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
    
    Pull workqueue / powernow-k8 fix from Tejun Heo:
     "This is the fix for the bug where cpufreq/powernow-k8 was tripping
      BUG_ON() in try_to_wake_up_local() by migrating workqueue worker to a
      different CPU.

and this is exactly the same BUG_ON I'm hitting. and powernowk8_target
is in the stack trace so it has to be the same issue.

I'll update my tree to latest Linus and retest.

Thanks for pointing this out.

-- 
Regards/Gruss,
Boris.