Kernel hangs system

[Mike Bernson]

This system work without problem on 4.13.0-45-generic but under 4.15.0-43-generic the system
hangs hard that event the keyboard cap-lock does not work.

This lockup is caused by do a number of zfs send/receive which is being using to backup a number
of zfs data sets. All of the send are being set to a single pool that is mirrored. Some of the
receive are from other systems on the local network. then I do a scrub of the backup pool. If I
try to ssh in to the system that is when it locks up. I also think the problem happens when
ext 4 file system is access.

Every thing work without any problem using when 4.13 kernel is in use. I wanted to look into
upgrading to 18.04 which is why I started using the 4.15 kernel.

This system also has lxc running on it.

Here is zfs setup:

root@server:~# zpool list
NAME SIZE ALLOC FREE EXPANDSZ FRAG CAP DEDUP HEALTH ALTROOT
backup 3.62T 1.88T 1.75T - 42% 51% 1.00x ONLINE -
lxc 444G 89.6G 354G - 12% 20% 1.00x ONLINE -
pool 3.62T 1.53T 2.10T - 47% 42% 1.00x ONLINE -
root@server:~#zpool status
  pool: backup
 state: ONLINE
  scan: scrub canceled on Sat Jan 12 18:39:38 2019
config:

 NAME STATE READ WRITE CKSUM
 backup ONLINE 0 0 0
   mirror-0 ONLINE 0 0 0
     ata-ST4000NM0024-1HT178_S4F0038H ONLINE 0 0 0
     ata-ST4000NM0024-1HT178_S4F00CV5 ONLINE 0 0 0

errors: No known data errors

  pool: lxc
 state: ONLINE
  scan: scrub repaired 0 in 0h5m with 0 errors on Sat Jan 12 16:18:44 2019
config:

 NAME STATE READ WRITE CKSUM
 lxc ONLINE 0 0 0
   ata-SAMSUNG_MZ7KM480HAHP-0E005_S2NGNX0H700696H ONLINE 0 0 0

errors: No known data errors

  pool: pool
 state: ONLINE
  scan: scrub canceled on Sat Jan 12 18:39:27 2019
config:

 NAME STATE READ WRITE CKSUM
 pool ONLINE 0 0 0
   mirror-0 ONLINE 0 0 0
     ata-ST4000NM0024-1HT178_Z4F0KC9L ONLINE 0 0 0
     ata-ST4000NM0024-1HT178_Z4F0KD00 ONLINE 0 0 0

errors: No known data errors

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: linux-image-generic-hwe-16.04 4.15.0.43.64
ProcVersionSignature: Ubuntu 4.13.0-45.50~16.04.1-generic 4.13.16
Uname: Linux 4.13.0-45-generic x86_64
NonfreeKernelModules: zfs zunicode zavl zcommon znvpair
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
Date: Sat Jan 12 18:46:08 2019
InstallationDate: Installed on 2016-02-09 (1068 days ago)
InstallationMedia: Ubuntu-Server 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/bin/bash
SourcePackage: linux-meta-hwe
UpgradeStatus: Upgraded to xenial on 2016-08-07 (888 days ago)