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

[Jeff]

Oh fun, trying to add multiple attachments, I just ended up finding a
bug report from 2007 complaining about apport being able to do this, but
the web interface is limited, so guess I'll get a bit spammy.

Ran into the same as usual again, even with avoiding heavy utilization.
Not seeing anything too interesting in the gathered info and apparently
the kernel log buffer is not large enough to be able to completely
handle a task list dump, but seems like most of the information is at
least there.

Will try to use RPCNFSDCOUNT=1 for some time in case this is a silly
deadlock, at least it's definitely easier to give it a try than to
downgrade to Ubuntu 22.04 which worked well.


** Attachment added: "dmesg.txt"
   https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/2062568/+attachment/5770300/+files/dmesg.txt

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Title:
  nfsd gets unresponsive after some hours of operation

Status in nfs-utils package in Ubuntu:
  Confirmed

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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