Re: [RFC PATCH 00/11] printk: safe printing in NMI context

[Jiri Kosina]

On Wed, 18 Jun 2014, Paul E. McKenney wrote:

> > - both RCU stall detector and 'echo l > sysrq-trigger' can (and we've 
> >   seen it happening for real) cause a complete, undebuggable, silent hang 
> >   of machine (deadlock in NMI context)
> 
> I could easily add an option to RCU to allow people to tell it not to
> use NMIs to dump the stack.  Would that help?

Well, that would make unfortunately the information provided by RCU stall 
detector rather useless ... workqueue-based stack dumping is very unlikely 
to point its finger to the real offender, as it'd be coming way too late.

Thanks,

-- 
Jiri Kosina
SUSE Labs
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