Date: Sat, 22 Sep 2007 22:35:45 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [BUG 2.6.23-rc6-mm1] NMI Watchdog detected LOCKUP on CPU 0
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On Sun, 23 Sep 2007 13:30:40 +0800 Fengguang Wu <wfg@mail.ustc.edu.cn> wrote:

> > That's interensting.  serial_in().  We have had NMI watchdog expiries when
> > the kernel is printing a large amount of stuff out a slow serial port with
> > interrutps disabled.  But I thought we'd pretty much plugged those problems
> > by sprinkling touch_nmi_watchdog() in various places.
> > 
> > Do you think this is what was happening on your system?
> 
> Very likely. I'm running linux with cmdline
> "root=/dev/sda1 ro nmi_watchdog=1 console=ttyS0,115200 console=tty0",
> and doing a lot of printks at the time ;-)

OK.  We need to find a suitable place to poke yet another
touch_nmi_watchdog().  Maybe we should give up and put one in
printk().

And you oopsed for different reasons in the nmi-watchdog handling
code too.  I think I'll pretend I didn't see that.

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