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

[Kris Kennaway]

Esa Karkkainen wrote:
> 	I get "Fatal double fault" error when writing to a filesystem
> mounted from NFS server.
> 
> 	Both NFS server and client are running 6.2-RELEASE-p7.
> 
> 	I've attached dmesg from client and kernel config from server
> and client.
> 
> 	Both have same these NFS options in /etc/rc.conf
> 
> rpcbind_enable="YES"
> nfs_server_enable="YES"
> nfs_client_enable="YES"
> nfs_reserved_port_only="YES"
> rpc_lockd_enable="YES"
> rpc_statd_enable="YES" 
> 
> 	I have three kernel crash dumps available.
> 
> 	The panic message is same in vmcore.0 and .1 
> 
> Fatal double fault:
> eip = 0xc0608015
> esp = 0xe3955000
> ebp = 0xe3955020
> panic: double fault
> 
> 	Panic message in vmcore.2 has different eip and ebp values.
> 
> Fatal double fault:
> eip = 0xc063242a
> esp = 0xe3955000
> ebp = 0xe3955008
> panic: double fault
> 
> 	And here is backtrace from vmcore.2, which is identical to
> backtrace found in vmcore.0 and vmcore.1.

Unfortunately the backtrace contains no information.

> # 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.

You might also update to RELENG_6, I think there was at least one bug 
fixed that might have caused such a thing.  Also try to rule out memory 
failure etc.

Kris