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

[Robert Williams]

Performed two upgrades from 22.04 yesterday, both have locked up
overnight with the below. It feels like this is the same issue - can
anyone confirm for me?

kernel: INFO: task nfsd:2029 blocked for more than 122 seconds.
kernel:       Tainted: G           OE      6.8.0-45-generic #45-Ubuntu
kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kernel: task:nfsd            state:D stack:0     pid:2029  tgid:2029  ppid:2      flags:0x00004000
kernel: Call Trace:
kernel:  <TASK>
kernel:  __schedule+0x27c/0x6b0
kernel:  ? __smp_call_single_queue+0xe0/0x180
kernel:  schedule+0x33/0x110
kernel:  schedule_timeout+0x157/0x170
kernel:  wait_for_completion+0x88/0x150
kernel:  __flush_workqueue+0x140/0x3e0
kernel:  ? nfsd4_run_cb+0x30/0x70 [nfsd]
kernel:  nfsd4_probe_callback_sync+0x1a/0x30 [nfsd]
kernel:  nfsd4_destroy_session+0x186/0x260 [nfsd]
kernel:  nfsd4_proc_compound+0x3b7/0x780 [nfsd]
kernel:  nfsd_dispatch+0xd7/0x220 [nfsd]
kernel:  svc_process_common+0x450/0x710 [sunrpc]
kernel:  ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
kernel:  svc_process+0x132/0x1b0 [sunrpc]
kernel:  svc_handle_xprt+0x4d3/0x5d0 [sunrpc]
kernel:  svc_recv+0x18b/0x2e0 [sunrpc]
kernel:  ? __pfx_nfsd+0x10/0x10 [nfsd]
kernel:  nfsd+0x8b/0xe0 [nfsd]
kernel:  kthread+0xf2/0x120
kernel:  ? __pfx_kthread+0x10/0x10
kernel:  ret_from_fork+0x47/0x70
kernel:  ? __pfx_kthread+0x10/0x10
kernel:  ret_from_fork_asm+0x1b/0x30
kernel:  </TASK>


Most annoying element is that nothing seems to allow recovery without a reload. Unless someone knows some trick to getting it back up?

These host VMs and the NFS share is purely for some bulk data backups. I
will shift them to the kernel mentioned above later today. If this
proves a fix, how soon may it roll out? I've got a large number of hosts
to move to 24.04 and will be holding off until this is fixed as it's
quite a showstopper.

Cheers!

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https://bugs.launchpad.net/bugs/2062568

Title:
  nfsd gets unresponsive after some hours of operation

Status in linux package in Ubuntu:
  Confirmed
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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