Reproducable, possibly NFS related, fatal double fault in 6.2-R-p7

[Esa Karkkainen]

On Sun, Oct 14, 2007 at 02:37:23PM +0200, Kris Kennaway wrote:
> Esa Karkkainen wrote:
> >	I get "Fatal double fault" error when writing to a filesystem
> >mounted from NFS server.

I got an offlist reply in which he suggested that the problem might be
in nve driver.

I installed an additional Intel nic, appropriate lines from dmesg are
as follows

fxp0: <Intel 82559 Pro/100 Ethernet> port 0xb000-0xb03f mem
0xe7200000-0xe7200fff,0xe7000000-0xe70fffff irq 11 at device 6.0 on pci1
miibus1: <MII bus> on fxp0
inphy0: <i82555 10/100 media interface> on miibus1
inphy0:  10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto

After I started to use fxp0, I can dump(8) all the necessary filesystems
to the NFS mount, with out panic.

When I used nve0 dump(8) or cp(1) managed to write less than megabyte to NFS
mount and then machine paniced.

It didn't matter if I made dump(8) write to the NFS mount or to a local
filesystem and then copied the file to NFS mount, the end result was a
panic.

> >	Both NFS server and client are running 6.2-RELEASE-p7.

Both machines have been updated to -p8.

> ># kgdb kernel.debug /home/crash/vmcore.2 
> >Fatal double fault:
> >eip = 0xc063242a
> 
> Can you look up these IPs in the kernel symbol table (see the developers 
> handbook)?  This might give at least one clue, although I'm not sure it 
> is relevant.

I'm sorry, but I need to learn alot more about gdb and debugging in
general before I can find that information. IIRC I have written about
ten or twenty lines of C in this millenia.

I do have matching kernel.debug and vmcore files, but kernel modules etc
have been removed before I made new kernel and world.

> You might also update to RELENG_6, I think there was at least one bug 
> fixed that might have caused such a thing.

At the moment I don't have any stability problems with this machine, but
I can upgrade to RELENG_6 before RELENG_6_3 is branched if that is
necessary.

> Also try to rule out memory failure etc.

This machine has two 512MB DDR333 DIMM's.

I installed sysutils/memtest and ran three simultaneously, first two
allocated 326 MB each and last one allocated 150 MB of memory, so I'd
start to swap. No errors.

I know these test are not conclusive, but I don't think DIMM's are 
faulty.

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