Re: "nfs server not responding, timed out" with Linux client and 13.0-RELEASE server

From: Alan Somers <>
Date: Wed, 02 Jun 2021 22:07:22 UTC
On Tue, Jun 1, 2021 at 7:09 PM Rick Macklem <> wrote:

> Alan Somers wrote:
> >I have several Linux NFS clients (Debian, with various 4.9 kernels)
> >mounting NFS 4.0 from both Solaris and FreeBSD (mostly 12.2-RELEASE)
> >servers.  I frequently see kernel messages in the clients about "nfs:
> >server <HOSTNAME> not responding, timed out" for both the FreeBSD and
> >Solaris servers.  It usually recovers after a few seconds.  However, on
> the
> >sole 13.0-RELEASE server, the hangs last for minutes to hours.
> >
> >tcpdump/wireshark shows the NFS client sending a "V4 Call SEQUENCE" packet
> >every 5-10 seconds, all with the same sessionid.  The server responds with
> >a TCP ACK, but sends no NFS-level response.  I've seen this with both NFS
> >4.0 and 4.2.
> >
> >NFS delegations are disabled, and nfsdumpstate shows that the client has
> >callbacks enabled, with 2-4 opens, openowners, locks, and lockowners.
> >
> >Can anybody suggest how to fix or further debug this problem?
> See PR#256280 for the ways to fix this, rick
> -Alan

Thanks for the tip, Rick!  I reverted the change mentioned in that PR, and
everything seems fine so far.