Re: [workqueue] WARNING: CPU: 0 PID: 76 at drivers/block/floppy.c:968 schedule_bh()

From: Jiri Kosina
Date: Fri Jul 11 2014 - 09:27:40 EST


On Tue, 8 Jul 2014, Jiri Kosina wrote:

> > > Hmmm... this is schedule_bh() in floppy.c complaining that the work
> > > item is already pending. The cond_resched() addition by b22ce2785d97
> > > doesn't change the semantics around work item execution although it
> > > could have exposed an existing problem in the floppy driver. I'll
> > > look into how this could happen.
> >
> > It doesn't reproduce here and nothing really stands out to me. It
> > probably involves floppy_work requeueing itself and something else
> > getting executed inbetween which wouldn't have happend before, but I
> > can't figure out what that could be and either can I follow the
> > control flow the driver. :)
> >
> >
> > Jiri, any ideas?
>
> I will take a look. Could this be a bad bisect though due to this actually
> being a race condition perhaps?

Fengguang, is it possible for you to confirm the bisection result (i.e.
revert the patch and check)?

I am having hard time seeing how it could cause this (and I am not able to
reproduce the problem myself).

Thanks,

--
Jiri Kosina
SUSE Labs
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