Comment 4 for bug 1788222

Applied the patch from -proposed:
root@Ubuntu1804:~# echo "deb http://archive.ubuntu.com/ubuntu/ bionic-proposed restricted main multiverse universe" | tee -a /etc/apt/sources.list
root@Ubuntu1804:~# apt-get update
root@Ubuntu1804:~# apt-get dist-upgrade
root@Ubuntu1804:~# shutdown -r 0

Verified that the -proposed contains fix:
root@Ubuntu1804:~# objdump -d /lib/modules/$(uname -r)/kernel/drivers/nvme/host/nvme.ko | grep -A 50 __nvme_submit_cmd\>: | grep fence
adf: 0f ae f8 sfence
ae6: 0f ae f0 mfence

(second mfence is the one added by patch)

Verified that the patch solves the issue:

./orion -run advanced -num_large 0 -size_small 8 -type rand -simulate concat -write 40 -duration 120 -matrix row -testname gcp_test

(no hang after 36 hours)

I assume that the same patch will be added to Xenial and Cosmic.