Re: [2.6.33-rc5] Weird deadlock when shutting down

From: Johannes Berg
Date: Thu Feb 18 2010 - 04:36:33 EST


On Fri, 2010-01-29 at 15:41 +1100, Benjamin Herrenschmidt wrote:
> Hi Ingo !
>
> Johannes and I see this on our quad G5s... it -could- be similar to
> one reported a short while ago by Xiaotian Feng <xtfeng@xxxxxxxxx>
> under the subject [2.6.33-rc4] sysfs lockdep warnings on cpu hotplug.
>
> Basically, the machine deadlocks right after printing the following
> when doing a shutdown:
>
> halt/4071 is trying to acquire lock:
> (s_active){++++.+}, at: [<c0000000001ef868>]
> .sysfs_addrm_finish+0x58/0xc0
>
> but task is already holding lock:
> (&per_cpu(cpu_policy_rwsem, cpu)){+.+.+.}, at: [<c0000000004cd6ac>]
> .lock_policy_rwsem_write+0x84/0xf4
>
> which lock already depends on the new lock.
>
> the existing dependency chain (in reverse order) is:

This is still happening with -rc8. Any news?

johannes

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