Re: Cyclictest results on Sparc64 with PREEMPT_RT

[Allen Pais <allen.pais@oracle.com>]

Sebastian,
> 
> This is a dead lock. Whatever lock you go after, you are already
> holding it in this context / hackbench. I don't know how you got from
> perfctr_irq() to do_exit() but you shouldn't do this in hardirq
> context.
> 
> But calling do_exit() is probably error recovery since it would kill
> hackbench and I assume it wasn't done yet.
> I see also tl0_irq15() in your stack trace. This is that evil NMI that
> checks if the system is stalling. I think that you stuck in
> flush_tsb_user() on that raw_lock and somebody is not letting it go and
> so you spin for ever. Maybe full lockdep shows you some informations
> about wrong context locking etc.
> 
Yes, there's someone's holding the lock and not releasing it in
flush_tsb_user(). I'll check with lockdep.

Thanks,
Allen