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Subject: Re: NFS Caching broken in 4.19.37
To:     Bruce Fields <bfields@fieldses.org>
Cc:     Salvatore Bonaccorso <carnil@debian.org>,
        Chuck Lever <chuck.lever@oracle.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "940821@bugs.debian.org" <940821@bugs.debian.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
        trond.myklebust@hammerspace.com, anna.schumaker@netapp.com
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From:   Anton Ivanov <anton.ivanov@cambridgegreys.com>
Organization: Cambridge Greys
Message-ID: <f0edfaf5-457d-2334-ee4f-a6bf9d13917b@cambridgegreys.com>
Date:   Sun, 21 Feb 2021 15:53:51 +0000
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On 21/02/2021 14:37, Bruce Fields wrote:
> On Sun, Feb 21, 2021 at 11:38:51AM +0000, Anton Ivanov wrote:
>> On 21/02/2021 09:13, Salvatore Bonaccorso wrote:
>>> On Sat, Feb 20, 2021 at 08:16:26PM +0000, Chuck Lever wrote:
>>>> Confirming you are varying client-side kernels. Should the Linux
>>>> NFS client maintainers be Cc'd?
>>> Ok, agreed. Let's add them as well. NFS client maintainers any ideas
>>> on how to trackle this?
>> This is not observed with Debian backports 5.10 package
>>
>> uname -a
>> Linux madding 5.10.0-0.bpo.3-amd64 #1 SMP Debian 5.10.13-1~bpo10+1
>> (2021-02-11) x86_64 GNU/Linux
> I'm still unclear: when you say you tested a certain kernel: are you
> varying the client-side kernel version, or the server side, or both at
> once?

Client side. This seems to be an entirely client side issue.

A variety of kernels on the clients starting from 4.9 and up to 5.10 
using 4.19 servers. I have observed it on a 4.9 client versus 4.9 server 
earlier.

4.9 fails, 4.19 fails, 5.2 fails, 5.4 fails, 5.10 works.

At present the server is at 4.19.67 in all tests.

Linux jain 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u2 (2019-11-11) 
x86_64 GNU/Linux

I can set-up a couple of alternative servers during the week, but so far 
everything is pointing towards a client fs cache issue, not a server one.

Brgds,

> --b.
>

-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/