hwclock can cause system lockup

[Tod Merley]

On Thu, Oct 16, 2008 at 8:19 AM, Chris Mocock
<chris1.noreply at googlemail.com> wrote:
> I've got an hourly cron job on some machines that runs "/sbin/hwclock --utc
> --hctosys" to sync the hardware clock to the system clock. These machines
> were recently upgraded from an old custom RH7.3 installation to a custom
> spin of Fedora 9 and started to occassionally lock up - every day or three.
> I noticed that they would always lock up at 1 minute past the hour so
> tracked it down to this cron job.
>
> I decided to test it on my standard Fedora 9 installation by running a
> simple script that runs the hwclock command every 3 seconds. Sure enough,
> the system ran for just over an hour before it locked up. By locked up I
> mean no activity, caps lock key doesn't work, can't ping, can't ssh in, but
> power is still on.
>
> Can anybody else confirm this? (Obviously on a non-critical machine as it
> may well cause a kernel crash!) Any ideas on where I should file a bug
> report or what other investigation I could do?
>
> Thanks, Chris.
>
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Hi Chris!

I have just some thoughts:

1. If you have not done so yet check out /var/log/messages - dmesg -
kernel.log - system... - root's mail -  It is always a good place to
start after a crash.

2. I note that it worked until the top of the hour - so - move the
task away from the top of the hour??

3. I remember some kernels having specific problems with specific
hardware clocks.  Try Googeling your specific hardware clocks model
number with Linux, Fedora, or the specific kernel.

4. Try more stack space?

5. Duke it out with a Kernel crash kit (may God help you!).

Good Hunting!

Tod