Re: nfsd becomes a zombie

Chuck Lever III
2024-06-17T14:32:21Z

> On Jun 17, 2024, at 2:55 AM, Harald Dunkel <harald.dunkel@aixigo.com> wrote:
>
> Hi folks,
>
> what would be the reason for nfsd getting stuck somehow and becoming
> an unkillable process? See
>
> - https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1071562
> - https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/2062568
>
> Doesn't this mean that something inside the kernel gets stuck as
> well? Seems odd to me.

I'm not familiar with the Debian or Ubuntu kernel packages. Can
the kernel release numbers be translated to LTS kernel releases
please? Need both "last known working" and "first broken" releases.

This:

[ 6596.911785] RPC: Could not send backchannel reply error: -110
[ 6596.972490] RPC: Could not send backchannel reply error: -110
[ 6837.281307] RPC: Could not send backchannel reply error: -110

is a known set of client backchannel bugs. Knowing the LTS kernel
releases (see above) will help us figure out what needs to be
backported to the LTS kernels kernels in question.

This:

[11183.290619] wait_for_completion+0x88/0x150
[11183.290623] __flush_workqueue+0x140/0x3e0
[11183.290629] nfsd4_probe_callback_sync+0x1a/0x30 [nfsd]
[11183.290689] nfsd4_destroy_session+0x186/0x260 [nfsd]

is probably related to the backchannel errors on the client, but
client bugs shouldn't cause the server to hang like this. We
might be able to say more if you can provide the kernel release
translations (see above).

--
Chuck Lever