Comment 77 for bug 1423672

We were recently hit by this issue, too on a physical x64 machine that hosts one kvm virtual machine guest with a windows server 2016 x64 operating system. The filesystem is a mdadm software raid1 spanning over two disks with ext4 on-top.

$ uname -r
4.15.0-43-generic

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 18.04.1 LTS
Release: 18.04
Codename: bionic

The filesystem of the physical machine went read only and effectively crashed all processes, including the guest operating system. A hard reset and disk check appears to have solved the symptom, but we have mixed feelings since we don't know about any collateral damage this may have caused. dmesg displays worrying information that is hopefully not a symptom of irreversible root filesystem corruption:

systemd-journald[457]: File /var/log/journal/7346ea28f12b763f29b8995058d63291/user-1000.journal corrupted or uncleanly shut down, renaming and replacing.

The symptom manifested while booting the guest machine and thus may well be related to a burst of random reads and writes of the kvm guest. We observed moderate disk activity in htop.