Re: INFO: possible circular locking dependency at cleanup_workqueue_thread

[Ming Lei]

2009/5/20 Johannes Berg <johannes@xxxxxxxxxxxxxxxx>:
> On Wed, 2009-05-20 at 11:36 +0800, Ming Lei wrote:
>
>> > Anyway, you can have a deadlock like this:
>> >
>> > CPU 3                   CPU 2                           CPU 1
>> >                                                        suspend/hibernate
>> >                        something:
>> >                        rtnl_lock()                     device_pm_lock()
>> >                                                        -> mutex_lock(&dpm_list_mtx)
>> >
>> >                        mutex_lock(&dpm_list_mtx)
>>
>> Would you give a explaination why mutex_lock(&dpm_list_mtx) runs in CPU2
>> and depends on rtnl_lock?
>
> Why not? Something is registering a hotplugged netdev.

I see. I just feel a bit curious how lockdep may build the dependency
of dpm_list_mtx on rtnl_lock,  and it  is certainly related with
lockdep internal.

-- 
Lei Ming
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