Re: [debug patch] printk: Add a printk killswitch to robustify NMIwatchdog messages

From: Mike Galbraith
Date: Mon Jun 06 2011 - 13:44:12 EST

On Mon, 2011-06-06 at 17:08 +0200, Ingo Molnar wrote:
> * Ingo Molnar <mingo@xxxxxxx> wrote:
> > The real fix might be to remove the lockdep_off()/on() call from
> > printk(), that looks actively evil ... we had to hack through
> > several layers of side-effects before we found the real bug - so
> > it's not like the off()/on() made things more robust!
> The other obvious fix would be to *remove* the blasted wakeup from
> printk(). It's a serious debugging robustness violation and it's not
> like the wakeup is super important latency-wise.
> We *already* have a timer tick driven klogd wakeup poll routine. So i
> doubt we'd have many problems from not doing wakeups from printk().
> Opinions?

Seconded! I routinely whack that damn thing.


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