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

[Joschi Brauchle <joschi.brauchle@tum.de>]

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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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