Comment 36 for bug 1668129

I've applied the udev rules change and it doesn't seem to make a difference on the instances I'm testing with:

(after applying the change and reloading udev, rebooting, etc)
ubuntu@hot-i3-muguasak:~$ cat /proc/zoneinfo
...
Node 0, zone Normal
  pages free 14714755
        min 7663
        low 22874
        high 38085
   node_scanned 0
        spanned 15499264
        present 15499264
        managed 15212046

ubuntu@hot-i3-muguasak:~$ cat /lib/udev/rules.d/40-vm-hotadd.rules
# On Hyper-V and Xen Virtual Machines we want to add memory and cpus as soon as they appear
ATTR{[dmi/id]sys_vendor}=="Microsoft Corporation", ATTR{[dmi/id]product_name}=="Virtual Machine", GOTO="vm_hotadd_apply"
ATTR{[dmi/id]sys_vendor}=="Xen", GOTO="vm_hotadd_apply"
GOTO="vm_hotadd_end"

LABEL="vm_hotadd_apply"

# Memory hotadd request
#SUBSYSTEM=="memory", ACTION=="add", DEVPATH=="/devices/system/memory/memory[0-9]*", TEST=="state", ATTR{state}="online"

# CPU hotadd request
SUBSYSTEM=="cpu", ACTION=="add", DEVPATH=="/devices/system/cpu/cpu[0-9]*", TEST=="online", ATTR{online}="1"

LABEL="vm_hotadd_end"

Errors are the same:
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.319668] EXT4-fs warning (device nvme0n1): ext4_end_bio:314: I/O error -5 writing to inode 108921589 (offset 4185915392 size
8388608 starting block 95900672)
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.319670] buffer_io_error: 246 callbacks suppressed
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.319671] Buffer I/O error on device nvme0n1, logical block 95900416
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.322738] Buffer I/O error on device nvme0n1, logical block 95900417
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.325826] Buffer I/O error on device nvme0n1, logical block 95900418
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.329083] Buffer I/O error on device nvme0n1, logical block 95900419
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.332017] Buffer I/O error on device nvme0n1, logical block 95900420
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.334949] Buffer I/O error on device nvme0n1, logical block 95900421
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.337913] Buffer I/O error on device nvme0n1, logical block 95900422
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.340918] Buffer I/O error on device nvme0n1, logical block 95900423
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.343829] Buffer I/O error on device nvme0n1, logical block 95900424
Mar 20 22:51:03 ip-172-30-4-8 kernel: [ 6797.346815] Buffer I/O error on device nvme0n1, logical block 95900425
Mar 20 22:51:04 ip-172-30-4-8 kernel: [ 6797.826561] JBD2: Detected IO errors while flushing file data on nvme0n1-8
Mar 20 22:51:26 ip-172-30-4-8 kernel: [ 6820.697487] JBD2: Detected IO errors while flushing file data on nvme0n1-8
Mar 20 22:51:36 ip-172-30-4-8 kernel: [ 6830.697208] JBD2: Detected IO errors while flushing file data on nvme0n1-8

Am I missing something obvious?