Re: Failure to release lock after CPU hot-unplug canceled

[Benjamin Gilbert <bgilbert@cs.cmu.edu>]

Heiko Carstens wrote:
> On Tue, Jan 09, 2007 at 05:57:40PM +0530, Srivatsa Vaddagiri wrote:
> > On Tue, Jan 09, 2007 at 01:17:38PM +0100, Heiko Carstens wrote:
> > > The workqueue code grabs a lock on CPU_[UP|DOWN]_PREPARE and releases it
> > > again on CPU_DOWN_FAILED/CPU_UP_CANCELED. If something in the callchain
> > > returns NOTIFY_BAD the rest of the entries in the callchain won't be
> > > called anymore. But DOWN_FAILED/UP_CANCELED will be called for every
> > > entry.
> > > So we might even end up with a mutex_unlock(&workqueue_mutex) even if
> > > mutex_lock(&workqueue_mutex) hasn't been called...
>>
> > This is a known problem. Gautham had sent out patches to address them
> >
> > http://lkml.org/lkml/2006/11/14/93
> >
> > Looks like they are in latest mm tree. Perhaps the testcase should be
> > retried against latest mm.
>
> Ah, nice! Wasn't aware of that. But I still think we should have a
> CPU_DOWN_FAILED in case CPU_DOWN_PREPARED failed.
> Also the slab cache code hasn't been changed to make use of the of the
> new CPU_LOCK_[ACQUIRE|RELEASE] stuff. I'm going to send patches in reply
> to this mail.

2.6.20-rc3-mm1 plus your patches fixes it for me.

Thanks
--Benjamin Gilbert

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