Re: 2.6.31-rc5 regression: x86 MCE malfunction on Thinkpad T42p

[Johannes Stezenbach <js@sig21.net>]

On Fri, Aug 07, 2009 at 07:09:42PM +0200, Johannes Stezenbach wrote:
> 
> I'm currently running linux-2.6.31-rc5-246-g90bc1a6 on
> an old Thinkpad T42p.  During boot I get the following:
...
> I guess I should try to boot with "lapic"?  But I think
> MCE worked without "lapic" in earlier kernels. On a 2.6.29.1
> kernel dmesg said:
> 
>    Local APIC disabled by BIOS -- you can enable it with "lapic"
>    ...
>    Intel machine check architecture supported.
>    Intel machine check reporting enabled on CPU#0.
> 
> 2.6.29.1 doesn't log any MCE events, so I doubt this is a HW problem.

I booted with "lapic", then the backtrace is gone
but it still logs machine check events which I think
are bogus since 2.6.29.1 does not log any.  I also
tried 2.6.30, no machine check messages in dmesg.  But
I noticed that mcelog complains about missing /dev/mcelog,
it seems that /dev/mcelog support for 32bit kernels is new.
However, I guess the old kernels should still have printed
a messge to dmesg, right?  "Uncorrected error" + "Processor
context corrupt" sounds pretty serious, but the machine
runs without problems.


These are from 2.6.31-rc5 by running mcelog (dmesg
just says "Machine check events logged"):


HARDWARE ERROR. This is *NOT* a software problem!
Please contact your hardware vendor
MCE 0
CPU 0 BANK 1 
TIME 1249725930 Sat Aug  8 12:05:30 2009
MCG status:
MCi status:
Error overflow
Uncorrected error
Error enabled
Processor context corrupt
MCA: MEMORY CONTROLLER AC_CHANNEL0_ERR
Transaction: Address/Command error
STATUS f2000000000000b0 MCGSTATUS 0
MCGCAP 5 APICID 0 SOCKETID 0 
CPUID Vendor Intel Family 6 Model 13
HARDWARE ERROR. This is *NOT* a software problem!
Please contact your hardware vendor
MCE 1
CPU 0 BANK 1 
TIME 1249728066 Sat Aug  8 12:41:06 2009
MCG status:
MCi status:
Error overflow
Uncorrected error
Error enabled
Processor context corrupt
MCA: Unknown Error 20
STATUS f200000000000020 MCGSTATUS 0
MCGCAP 5 APICID 0 SOCKETID 0 
CPUID Vendor Intel Family 6 Model 13
HARDWARE ERROR. This is *NOT* a software problem!
Please contact your hardware vendor
MCE 2
CPU 0 BANK 1 
TIME 1249747923 Sat Aug  8 18:12:03 2009
MCG status:
MCi status:
Error overflow
Uncorrected error
Error enabled
Processor context corrupt
MCA: Unknown Error 30
STATUS f200000000000030 MCGSTATUS 0
MCGCAP 5 APICID 0 SOCKETID 0 
CPUID Vendor Intel Family 6 Model 13
HARDWARE ERROR. This is *NOT* a software problem!
Please contact your hardware vendor
MCE 3
CPU 0 BANK 1 
TIME 1249765938 Sat Aug  8 23:12:18 2009
MCG status:
MCi status:
Error overflow
Uncorrected error
Error enabled
Processor context corrupt
MCA: Unknown Error 20
STATUS f200000000000020 MCGSTATUS 0
MCGCAP 5 APICID 0 SOCKETID 0 
CPUID Vendor Intel Family 6 Model 13


Johannes