Re: kernel BUG at drivers/md/raid5.c:693!

From: NeilBrown
Date: Mon Nov 25 2013 - 23:31:25 EST


On Mon, 25 Nov 2013 10:53:23 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx>
wrote:

> On Mon, Nov 25, 2013 at 10:35:22AM +1100, NeilBrown wrote:
> > Ingo/Peter: is it considered OK to call wake_up while holding a spinlock?
>
> Yes, very much so. Doing a wakeup isn't _that_ expensive.

Oh good. Thanks.

>
> > Could "sleeping spinlocks" affect this at all? (some sample stack traces are
> > below).
>
> Not entirely sure, are you referencing to -rt where me make spinlock_t
> pi-mutexes?

I'm not sure either. Just stabbing in the dark really.

The stack trace in the previous email seemed to suggest that a process was
blocking inside a wake_up call, but it wasn't at all conclusive. And I've
seen a few wake_ups in other stack traces which seem to be connected with
other deadlock. Probably some sort of co-incidence.

Thanks,
NeilBrown

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