Re: NFSv4 poops itself

[Trond Myklebust <Trond.Myklebust@netapp.com>]

On Fri, 2007-07-27 at 08:53 -0400, Jeff Garzik wrote:
> Background:
> 
> Server: x86-64 dual core Intel, kernel 2.6.23-rc1 (my home fileserver)
> 	Exporting NFS/NFSv4 mounts.  Client count: 1  Uptime: 4 days
> 
> Client: x86-64 dual core Intel, kernel 2.6.23-rc1 (my main workstation)
> 	NFS mount setup:
> 	pretzel:/ on /g type nfs4 (rw,noatime,proto=tcp,addr=10.10.10.1)
> 	Uptime: 4 days
> 
> 	Home directory mounted via NFSv4.
> 
> Problem:
> 
> My workstation has been happily talking to my file server for several 
> days without incident.  An hour ago, my numeric keypad stopping working 
> (unrelated problem... USB or X bug?).  The solution to the keypad 
> problem is usually to log out of X and log back in, or worse case, reboot.
> 
> So, I log out, and log back in.  At first, a few shell windows open and 
> successfully initialize themselves (read bash profile over NFS, etc.) 
> Then, as more shell windows open, things start hanging.  I can easily 
> switch to console and ssh to the fileserver, so it is clear this is an 
> NFS hang.
> 
> No adverse messages at all on the client.
> 
> On the server, I see NFSv4 spamming dmesg with hundreds of thousands of 
> messages:
> 
> Jul 27 08:20:53 pretzel kernel: NFSD: preprocess_seqid_op: old stateid!
> Jul 27 08:21:24 pretzel last message repeated 167966 times
> Jul 27 08:21:55 pretzel last message repeated 173628 times
> Jul 27 08:21:55 pretzel kernel: NFSD: preprocess_seqid_op: old stateid!
> Jul 27 08:22:26 pretzel last message repeated 171286 times
> Jul 27 08:23:27 pretzel last message repeated 344461 times
> Jul 27 08:23:30 pretzel last message repeated 18656 times
> 
> I rebooted the client, the problem disappeared, and everything is happy 
> again...  but clearly NFSv4 shat itself.  And now I am worried this will 
> happen again.
> 
> In all my quite-heavy use of NFSv4 I've never seen this behavior before, 
>   so I would call this a regression.

Yup. Bruce has reported the same bug so it is under investigation. I'll
keep you posted when I think we have a fix.

Cheers
  Trond