Message-ID: <390526785.26292@ustc.edu.cn>
Date: Sun, 23 Sep 2007 13:53:03 +0800
From: Fengguang Wu <wfg@mail.ustc.edu.cn>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>
Subject: Re: [BUG 2.6.23-rc6-mm1] NMI Watchdog detected LOCKUP on CPU 0
Message-ID: <20070923055303.GA14899@mail.ustc.edu.cn>
References: <20070918011841.2381bd93.akpm@linux-foundation.org> <390511737.19669@ustc.edu.cn> <20070922212236.db145c57.akpm@linux-foundation.org> <390525442.01749@ustc.edu.cn> <20070922223545.a1bdb1b5.akpm@linux-foundation.org>
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On Sat, Sep 22, 2007 at 10:35:45PM -0700, Andrew Morton wrote:
> 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.

Let's forget it for now.
I can try Ingo's latency tracing patches at some convenient time.

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