Re: nfsd becomes a zombie

Calum Mackay
2024-06-17T19:21:29Z

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On 17/06/2024 3:31 pm, Chuck Lever III wrote:
>
>
>> 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

The Debian NFS server's broken kernel corresponds to upstream stable
6.1.90. There doesn't seem to be any note of a working version.

Decoding the Ubuntu pkg version is harder (but is obviously the 6.8.y
series; the actual corresponding 'y' value is printed during boot, but
other than downloading the pkg source, I'm not sure how to find it
otherwise). The older Ubuntu mentioned in the bug as seeing the nfsd
issue will be 6.5.y.

Harald: do you have a Debian/Ubuntu kernel version that doesn't see the
issue, please? i.e. ideally from the same 6.1.y series…

cheers,
c.

> 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
>
>

--
Calum Mackay
Linux Kernel Engineering
Oracle Linux and Virtualisation

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