Re: Lockup with 2.6.9-ac15 related to netconsole

From: Matt Mackall
Date: Tue Dec 21 2004 - 16:29:42 EST

On Tue, Dec 21, 2004 at 09:48:53PM +0100, Francois Romieu wrote:
> Mark Broadbent <markb@xxxxxxxxxxxxxx> :
> [...]
> > Using the patch supplied I get no hang, just the message 'netconsole
> > raced' output to the console and the packet capture proceeds as normal.
> > Thanks
> The patch is more a bandaid for debugging than a real fix. The netconsole
> will drop some messages until its locking is fixed

Unfortunately there's no good way to fix its locking in this
circumstance (or the harder case of driver-private locks). I think
I'll just have to come up with some scheme for queueing messages that
arrive when the queue lock is held.

> If you can issue one more test, I'd like to know if some messages appear
> on the VGA console around the time at which tcpdump is started (the test
> assumes that netconsole is not used/insmoded at all). Please check that
> the console log_level is set high enough as it will be really disappointing
> if nothing appears :o)

I think it's the promiscuous mode message itself that's the problem
but I've not had time to reproduce it.

Mathematics is the supreme nostalgia of our time.
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