Comment 2 for bug 2062568

This kind of issue appeared with Ubuntu 23.10 for me on the server mostly using an HDD for bulk storage with a not exactly powerful CPU also being occupied with using WireGuard to secure the NFS connection.

Mentioning the performance details because I have a feeling they matter. An also not exactly high performance client connecting over 1 Gb/s only very occasionally caused this problem, however given a 10 Gb/s connection, the issue appeared significantly more commonly. A higher performance setup utilizing a 2.5 Gb/s connection triggered this bug in a couple of days after setup.
The lockup always seem to occur with heavy NFS usage, suspiciously mostly when there's both reading and writing going on, at least I don't recall it happening with reading only, but I'm not confident in stating it didn't happen with a writing only load.

Found this bug report by the client error message, server side differs due to the different version:
```
[300146.046666] INFO: task nfsd:1426 blocked for more than 241 seconds.
[300146.046732] Not tainted 6.5.0-27-generic #28~22.04.1-Ubuntu
[300146.046770] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[300146.046813] task:nfsd state:D stack:0 pid:1426 ppid:2 flags:0x00004000
[300146.046827] Call Trace:
[300146.046832] <TASK>
[300146.046839] __schedule+0x2cb/0x750
[300146.046860] schedule+0x63/0x110
[300146.046870] schedule_timeout+0x157/0x170
[300146.046881] wait_for_completion+0x88/0x150
[300146.046894] __flush_workqueue+0x140/0x3e0
[300146.046908] nfsd4_probe_callback_sync+0x1a/0x30 [nfsd]
[300146.047074] nfsd4_destroy_session+0x193/0x260 [nfsd]
[300146.047219] nfsd4_proc_compound+0x3b7/0x770 [nfsd]
[300146.047365] nfsd_dispatch+0xbf/0x1d0 [nfsd]
[300146.047497] svc_process_common+0x420/0x6e0 [sunrpc]
[300146.047695] ? __pfx_read_tsc+0x10/0x10
[300146.047706] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
[300146.047848] ? __pfx_nfsd+0x10/0x10 [nfsd]
[300146.047977] svc_process+0x132/0x1b0 [sunrpc]
[300146.048157] nfsd+0xdc/0x1c0 [nfsd]
[300146.048287] kthread+0xf2/0x120
[300146.048299] ? __pfx_kthread+0x10/0x10
[300146.048310] ret_from_fork+0x47/0x70
[300146.048321] ? __pfx_kthread+0x10/0x10
[300146.048331] ret_from_fork_asm+0x1b/0x30
[300146.048341] </TASK>
```

This seems to be matching, but the previous lockups experienced may have been somewhat different.
I mostly remember the client whining about the server not responding instead of the message presented here, and the server call trace used to have btrfs in it which made me suspect it may be exclusive to that, although the issue was always with NFS, nothing else locked up despite having some other sources of heavy I/O.