[Bug 2062568] Re: nfsd gets unresponsive after some hours of operation

@mehmetbasaran: This issue is impacting one of the HPC clusters I
manage. Are there any thoughts as to when this patch will get rolled out
to a released 6.8.0 kernel?


Also, does anyone know if this is a server bug or a client bug, i.e. for mitigation, do the servers need to be rolled back to a version that does not have the bug? Do the clients need to be rolled back? Both?

Thanks,
Omen

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Title:
nfsd gets unresponsive after some hours of operation

Status in linux package in Ubuntu:
In Progress
Status in nfs-utils package in Ubuntu:
Incomplete
Status in linux source package in Noble:
In Progress
Status in nfs-utils source package in Noble:
Incomplete

Bug description:
I installed the 24.04 Beta on two test machines that were running
22.04 without issues before. One of them exports two volumes that are
mounted by the other machine, which primarily uses them as a secondary
storage for ccache.

After being up for a couple of hours (happened twice since yesterday
evening) it seems that nfsd on the machine exporting the volumes hangs
on something.

From dmesg on the server (repeated a few times):

[11183.290548] INFO: task nfsd:1419 blocked for more than 1228 seconds.
[11183.290558] Not tainted 6.8.0-22-generic #22-Ubuntu
[11183.290563] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[11183.290582] task:nfsd state:D stack:0 pid:1419 tgid:1419 ppid:2 flags:0x00004000
[11183.290587] Call Trace:
[11183.290602] <TASK>
[11183.290606] __schedule+0x27c/0x6b0
[11183.290612] schedule+0x33/0x110
[11183.290615] schedule_timeout+0x157/0x170
[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]
[11183.290744] nfsd4_proc_compound+0x3af/0x770 [nfsd]
[11183.290798] nfsd_dispatch+0xd4/0x220 [nfsd]
[11183.290851] svc_process_common+0x44d/0x710 [sunrpc]
[11183.290924] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
[11183.290976] svc_process+0x132/0x1b0 [sunrpc]
[11183.291041] svc_handle_xprt+0x4d3/0x5d0 [sunrpc]
[11183.291105] svc_recv+0x18b/0x2e0 [sunrpc]
[11183.291168] ? __pfx_nfsd+0x10/0x10 [nfsd]
[11183.291220] nfsd+0x8b/0xe0 [nfsd]
[11183.291270] kthread+0xef/0x120
[11183.291274] ? __pfx_kthread+0x10/0x10
[11183.291276] ret_from_fork+0x44/0x70
[11183.291279] ? __pfx_kthread+0x10/0x10
[11183.291281] ret_from_fork_asm+0x1b/0x30
[11183.291286] </TASK>

From dmesg on the client (repeated a number of times):
[ 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

ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: nfs-kernel-server 1:2.6.4-3ubuntu5
ProcVersionSignature: Ubuntu 6.8.0-22.22-generic 6.8.1
Uname: Linux 6.8.0-22-generic x86_64
.etc.request-key.d.id_resolver.conf: create id_resolver * * /usr/sbin/nfsidmap -t 600 %k %d
ApportVersion: 2.28.1-0ubuntu1
Architecture: amd64
CasperMD5CheckResult: pass
Date: Fri Apr 19 14:10:25 2024
InstallationDate: Installed on 2024-04-16 (3 days ago)
InstallationMedia: Ubuntu-Server 24.04 LTS "Noble Numbat" - Beta amd64 (20240410.1)
NFSMounts:

NFSv4Mounts:

ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 TERM=xterm-256color
 XDG_RUNTIME_DIR=<set>
SourcePackage: nfs-utils
UpgradeStatus: No upgrade log present (probably fresh install)

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