Re: Suspend resume problem (WAS Re: [ANNOUNCE] 3.8.10-rt6)

[Steven Rostedt]

On Fri, 2013-05-03 at 11:59 +0200, Sebastian Andrzej Siewior wrote:
>  
> > As the NMI dump only happens because of the time jump, which as you
> > said, is -rt only, I wouldn't say that the NMI deadlock is a mainline
> > bug.
> 
> The reason for the NMI was a bug in the -RT tree but if something else
> triggers that NMI we have a good chance to deadlock.

But only if the NMI does a printk(). The only reason NMIs do printks is
when a bug is detected. But usually oops_in_progress() is called and
also zap_locks() is suppose to help prevent these problems. But that
doesn't always work.

> 
> What about a try_lock() and leave after 50 usecs of trying and not
> getting it in the in_nmi() case?

I wouldn't try too hard to fix printks for NMIs. There's many things
that can go wrong with NMIs doing a printk while another printk is
active.

-- Steve


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/