Re: [REGRESSION] reads and writes hang if NFS server has v3 disabled

["Chuck Lever" <cel@kernel.org>]

[ Adding correct addresses from MAINTAINERS ]

On Fri, Sep 4, 2026, at 9:05 AM, Chuck Lever wrote:
> I'm using a minimal Fedora 45 VM (kvm) for testing.   I export a
> directory with rw and mount it from my personal computer running Fedora
> 45 as well. If /etc/nfs. conf has vers3=n, then reads and writes hang in
> D+ state, and there's a continuous
>
>
> I'm using a minimal Fedora 45 VM (kvm) for testing.  I export a 
> directory with rw and mount it from my personal computer running Fedora 
> 45 as well.
> If /etc/nfs.conf has vers3=n, then reads and writes hang in D+ state, 
> and there's a continuous loop of V3 NULL calls, with the server replying 
> that it only supports v4.
> If nfs.conf has vers3=y, then the reads and writes succeed.
> Introduced in 70b7e3526c53d9dd, still present in the latest 
> mainline/master (841e384b841a).
>
> The hung state can be rescued by changing the setting and restarting 
> nfs-server, at which point the read/write will complete.
>
> I can do more testing / get more information as needed.
>
> Here's links to pcap files with it working/bugged:
> http://grepper.net/lkml-files/nfs-working.pcap
> http://grepper.net/lkml-files/nfs-bugged.pcap
> http://grepper.net/lkml-files/nfs-bug-kernel.config
>
> #regzbot introduced:  70b7e3526c53d9dd7caccdbeff5b0485640d8cf1

It's not immediately obvious to me why 70b7e3526c53d9dd should
cause this kind of behavior regression.

Jeff, it's a netlink change. Can you triage?


-- 
Chuck Lever (Come to NFS bake-a-thon! https://nfsv4bat.org)