Subject: Re: [PATCH] softlockup: fix problem with long kernel pauses from
 kgdb
From: Peter Zijlstra <peterz@infradead.org>
To: Jason Wessel <jason.wessel@windriver.com>
Cc: Ingo Molnar <mingo@elte.hu>, lkml <linux-kernel@vger.kernel.org>,
       "Deng, Dongdong" <Dongdong.Deng@windriver.com>
In-Reply-To: <4A6E0825.3020604@windriver.com>
References: <4A6E0825.3020604@windriver.com>
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Date: Mon, 27 Jul 2009 22:18:13 +0200
Message-Id: <1248725893.6987.2055.camel@twins>
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On Mon, 2009-07-27 at 15:03 -0500, Jason Wessel wrote:
> 
> The fix is to simply invoke sched_clock_tick() to update "cpu sched
> clock" on exit from kgdb_handle_exception.

Is that a regular IRQ context, or is that NMI context?

> Signed-off-by: Dongdong Deng <Dongdong.Deng@windriver.com>
> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
> Cc: Ingo Molnar <mingo@elte.hu>
> Cc: peterz@infradead.org
> ---
>  kernel/softlockup.c |    3 +++
>  1 file changed, 3 insertions(+)
> 
> --- a/kernel/softlockup.c
> +++ b/kernel/softlockup.c
> @@ -118,6 +118,9 @@ void softlockup_tick(void)
>         }
>  
>         if (touch_timestamp == 0) {
> +               /* If the time stamp was touched externally make sure the
> +                * scheduler tick is up to date as well */
> +               sched_clock_tick();
>                 __touch_softlockup_watchdog();
>                 return;
>         }
> 

Aside from the funny comment style (please fix) the fix does look
sensible.
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