Re: Crash when unmounting NFS/TCP with -f

[Brice Goglin <Brice.Goglin@ens-lyon.org>]

Bill Davidsen a écrit :
> Brice Goglin wrote:
> 
>> Hi Trond,
>>
>> I'm using NFS (v2) over TCP (in a SSH tunnel).
>> Each time the SSH dies before a umount NFS, I have to umount -f
>> and I get a crash (only sysrq works).
>> Actually, the crash occurs a few seconds after umount -f.
>>
>> It seems that killing SSH by hand does _not_ lead to crash.
>> But a long network failure does.
>> I remember seeing this bug several times with all stable releases
>> from 2.6.7 to 2.6.11. I didn't try with earlier versions.
>>
>> I didn't see anything in the logs (after reboot). But I can't be sure
>> there was nothing in dmesg since I didn't get a chance to chvt 1 and
>> see console messages before rebooting (with sysrq).
>>
>> Do you have any idea how to debug this ?
> 
> 
> No clue, but a question: is this a hard or soft mount? Could you post 
> your ssh and mount commands, munged as needed for security? That might 
> give someone a clue.

The ssh command is just
$ ssh kwad -L 2249:localhost:2049 -L 2248:localhost:870 -N -f
(port is forwarded to 2249 while mountport if forwarded to 2248)

Options is /proc/mounts are
rw,v2,rsize=8192,wsize=8192,hard,tcp,nolock,addr=localhost

I just had another network failure. I ran umount -f from vt1 to see
kernel message. I waited for about 1 minute but didn't get any crash.
So I switched back to X... and got the crash then.
Looks like this crash doesn't want me to see any message...

Brice