Re: Deadlocks due to per-process plugging

[Thomas Gleixner]

On Fri, 13 Jul 2012, Jan Kara wrote:
> On Fri 13-07-12 16:25:05, Thomas Gleixner wrote:
> > So the patch below should allow the unplug to take place when blocked
> > on mutexes etc.
>   Thanks for the patch! Mike will give it some testing.

I just found out that this patch will explode nicely when the unplug
code runs into a contended lock. Then we try to block on that lock and
make the rtmutex code unhappy as we are already blocked on something
else.

So no, it's not a solution to the problem. Sigh.

Can you figure out on which lock the stuck thread which did not unplug
due to tsk_is_pi_blocked was blocked?

Thanks,

	tglx
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