Re: Crash when unmounting NFS/TCP with -f

From: Brice Goglin
Date: Tue Apr 26 2005 - 02:53:25 EST

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

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...

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