Re: INFO: possible circular locking dependency atcleanup_workqueue_thread

From: Johannes Berg
Date: Tue May 19 2009 - 04:52:20 EST


On Mon, 2009-05-18 at 21:47 +0200, Oleg Nesterov wrote:

> > Maybe it shouldn't do that from the CPU_POST_DEAD
> > notifier?
>
> Well, in any case we should understand why we have the problem, before
> changing the code. And CPU_POST_DEAD is not special, why should we treat
> it specially and skip lock_map_acquire(wq->lockdep_map) ?

I'm not familiar enough with the code -- but what are we really trying
to do in CPU_POST_DEAD? It seems to me that at that time things must
already be off the CPU, so ...? On the other hand that calls
flush_cpu_workqueue() so it seems it would actually wait for the work to
be executed on some other CPU, within the CPU_POST_DEAD notification?

johannes

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