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Subject: Re: INFO: possible circular locking dependency at 
 cleanup_workqueue_thread
From: Johannes Berg <johannes@sipsolutions.net>
To: Ming Lei <tom.leiming@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@elte.hu>,
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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/hibernat=
e
> >                        something:
> >                        rtnl_lock()                     device_pm_lock()
> >                                                        -> mutex_lock(&d=
pm_list_mtx)
> >
> >                        mutex_lock(&dpm_list_mtx)
>=20
> 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.

johannes

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