Re: NFS Client looping with STALE_STATE_ID error - 100% load on one CPU core

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Hello Ben,

thanks for the hint. I checked the kernel and it already includes this patch, but still gets stuck in this STALE_ID -> RENEW -> STALE_ID loop...

Best regards,
J Brauchle

On 05/05/2015 07:24 PM, Benjamin Coddington wrote:
Hi J Brauchle,

Are you producing this on a kernel that has "8faaa6d Fixing lease renewal"?
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8faaa6d5d48b2015

If not, I think that might be what you need.

Ben

On Thu, 23 Apr 2015, Joschi Brauchle wrote:

Hello everyone,

I am posting to this list as suggested by Neil F Brown in this OpenSUSE
bugzilla: https://bugzilla.novell.com/show_bug.cgi?id=909634


We are mounting user homes and other shares using 'sec=krb' and NFSv4. With
kernel 3.16.7+ (includes latest NFS patches, please see BZ link for details)
we are seeing 100% CPU core usage by a kernel process on some machine
connected to a 'NetApp FAS 3140 with ONTAP 8.1.4P1 7-mode' NFSv3/4 Server. It
looks like the problem is triggered when the NFS server is unavailable for a
short period of time or was rebooted.

Neil F Brown has come to the following conclusion so far:
------------- QUOTE -------------
What I see happening here is that a WRITE or LOCK request gets
NFS4ERR_STALE_STATEID, and then the client sends a "RENEW" request.

If the stateid is really stale, that should fail, but it doesn't. So the
client assumes everything is OK and keeps sending requests .... which fail
with NFS4ERR_STALE_STATEID.

STALE_STATEID means:

       A stateid generated by an earlier server instance was used.

which means that the server must have restarted since that stateid was issued.

So there seem to be two possible explanations:

1/ The server is lying.  The stateid isn't really 'stale'.  Maybe it is 'bad'.
2/ The client has previously handled a STALE_STATEID error and created a new
"client" handle, but hasn't refreshed all of the stateids that it was holding.
So it is trying to use old stateid even though it has established a new
client.

The client code looks OK, though it is sufficiently complex that I cannot be
certain.  There are no patches in more recent versions.
-------------  END  -------------

We have some RPC/NFS debug logs available here:
https://bugzilla.novell.com/attachment.cgi?id=631962
And a wireshark trace here:
https://bugzilla.novell.com/attachment.cgi?id=632104


What I cannot do:
- Trigger or reproduce the problem reliably. It comes up every once in a
while. Around 2-3 times a month on a handful of ~50 machines.
- Provide logs from with the latest kernel (because I cannot trigger the
problem by any means. Updating all ~50 machines is not an option)


What I can do:
- Provide logs from or possibly even access to the machine in the 'broken'
state for the next couple of days. I will have to reboot it at some time to
take the load of the NFS server.



I would be grateful for any help or comments.

-J Brauchle

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