SMP forcing crash/reboot in 4.9-STABLE

[Alasdair Lumsden]

> We have a 4-way P3/500 Xeon system running FreeBSD.  We had been
running
> 4.8-STABLE for a number of months with SMP enabled and no issues.
Around
> 25-November we moved to 4.9-STABLE.  The system ran without SMP
enabled
> until Tuesday, when we enabled SMP and APIC_IO, rebuilt the kernel,
and
> rebooted.  Then about every 30 minutes the system would reboot.  We
moved
> back to single-processor (using the source updated on 25-Nov) and it
has
> worked since.
> 
> So we synced source last night and tried enabling SMP again this
morning.
> We are still seeing the same problem.  We have switched back to a
non-SMP
> kernel (from last night's sync) and are running fine.
> 
> Has anyone else seen this?  Any ideas where to look?  There is nothing
in
> messages or dmesg about the crash, and I haven't been able to catch it
at
> the console to see if there's a message there.

We recently purchased a Dual Xeon 2.8GHz machine, and stuck FreeBSD
4.9-STABLE on it. The Kernel has SMP+APIC enabled, and HyperThreading is
disabled in the system's bios.

The server was put to use in a production environment, and is handling
quite a high volume of web traffic. Since it was put into service almost
a week ago, it has crashed randomly 2 or 3 times. Of course, since this
is a new server, it's impossible to say whether our two problems are
linked, or whether this is a hardware/configuration problem.

If the problem persists, I'll recompile with a non-SMP enabled kernel
and see if this fixes the problem. If it does, I'll be sure to let you
know. Unfortunately since the times between crashes seem random, it
might be a week or two until I have any conclusive answers.