Hello today one of our servers died when unmounting SMB mount. 
There were multiple messages on console and the server was unresponsive (SSH, console etc. weren't working at all):
May 22 04:43:59 XXXXXXX kernel: [13445315.881356] BUG: soft lockup - CPU#16 stuck for 23s! [yyyyyyy:81602]

OS: Ubuntu 22.04.4 LTS (server) on proxmox
Kernel version: Linux version 5.15.0-106-generic (buildd@lcy02-amd64-017) (gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0, GNU ld (GNU Binutils for Ubuntu) 2.38) #116-Ubuntu SMP Wed Apr 17 09:17:56 UTC 2024 (Ubuntu 5.15.0-106.116-generic 5.15.149)

Last messages in kern.log and syslog.log were from Veeam agent which is mounting SMB and unmounting it after the job is done.

kern.log:
May 21 20:58:50 XXXXXX kernel: [782127.570070] CIFS: Attempting to mount \\XX.YY.ZZ.XX\mountname
May 21 20:58:51 XXXXXX kernel: [782127.825476] CIFS: VFS: parse_server_interfaces: malformed interface info
May 22 02:31:32 XXXXXX kernel: [802088.671096] CIFS: Attempting to mount \\XX.YY.ZZ.XX\mountname
May 22 02:31:32 XXXXXX kernel: [802089.053850] CIFS: VFS: parse_server_interfaces: malformed interface info

syslog.log:
May 22 02:31:32 XXXXXX kernel: [802088.671096] CIFS: Attempting to mount \\XX.YY.ZZ.XX\mountname
May 22 02:31:32 XXXXXX kernel: [802089.053850] CIFS: VFS: parse_server_interfaces: malformed interface info
May 22 02:31:41 XXXXXX kernel: [802097.813546] veeamblksnap-snapshot: Create snapshot for devices:
May 22 02:31:41 XXXXXX kernel: [802097.813548] veeamblksnap-snapshot:        8:1
May 22 02:31:41 XXXXXX kernel: [802097.813549] veeamblksnap-snapshot:        8:14
May 22 02:31:41 XXXXXX kernel: [802097.813550] veeamblksnap-snapshot:        8:15
May 22 02:31:41 XXXXXX kernel: [802097.813554] veeamblksnap-snapshot: Snapshot a4f19dd1-aa06-4530-ba95-58876195b6ae was created
May 22 02:31:41 XXXXXX kernel: [802098.053228] veeamblksnap-snapshot: Snapshot was taken successfully
May 22 02:31:41 XXXXXX kernel: [802098.053232] veeamblksnap-snapimage: Create snapshot image device [252:0] for original device [8:1]
May 22 02:31:41 XXXXXX kernel: [802098.053638] veeamblksnap-snapimage: Create snapshot image device [252:1] for original device [8:14]
May 22 02:31:41 XXXXXX kernel: [802098.053996] veeamblksnap-snapimage: Create snapshot image device [252:2] for original device [8:15]
May 22 02:31:41 XXXXXX systemd-udevd[580471]: veeamblksnapimg1: Process '/usr/bin/unshare -m /usr/bin/snap auto-import --mount=/dev/veeamblksnapimg1' failed with exit code 1.
May 22 02:31:41 XXXXXX systemd-udevd[580473]: veeamblksnapimg2: Process '/usr/bin/unshare -m /usr/bin/snap auto-import --mount=/dev/veeamblksnapimg2' failed with exit code 1.
May 22 02:31:41 XXXXXX systemd-udevd[580469]: veeamblksnapimg0: Process '/usr/bin/unshare -m /usr/bin/snap auto-import --mount=/dev/veeamblksnapimg0' failed with exit code 1.
May 22 02:31:45 XXXXXX kernel: [802101.736250] EXT4-fs (veeamblksnapimg0): 8 orphan inodes deleted
May 22 02:31:45 XXXXXX kernel: [802101.736254] EXT4-fs (veeamblksnapimg0): recovery complete
May 22 02:31:45 XXXXXX kernel: [802101.736619] EXT4-fs (veeamblksnapimg0): mounted filesystem with ordered data mode. Opts: (null). Quota mode: none.
May 22 02:31:45 XXXXXX systemd[1]: tmp-veeam-\x7b023d917d\x2d51b7\x2d4364\x2d9b9e\x2de9a653a7c851\x7d.mount: Deactivated successfully.
May 22 06:20:07 XXXXXX systemd[1]: Mounted Huge Pages File System.
May 22 06:20:07 XXXXXX systemd[1]: Mounted POSIX Message Queue File System.
May 22 06:20:07 XXXXXX systemd[1]: Mounted Kernel Debug File System.
May 22 06:20:07 XXXXXX systemd[1]: Mounted Kernel Trace File System.
May 22 06:20:07 XXXXXX systemd[1]: Finished Set the console keyboard layout.
May 22 06:20:07 XXXXXX kernel: [    0.000000] Linux version 5.15.0-107-generic (buildd@lcy02-amd64-012) (gcc (Ubuntu

The system rebooted with newer kernel 5.15.0-107-generic but before crash it was 5.15.0-106-generic.

I can still see these messages in newer kernel:
May 22 06:26:13 XXXXXX kernel: [802089.053850] CIFS: VFS: parse_server_interfaces: malformed interface info