Comment 34 for bug 1668129

Excellent. Sanity check here: This also means that trusty is not affected because the udev rules don't match.

I have /lib/udev/rules.d/40-hyperv-hotadd.rules:

# On Hyper-V Virtual Machines we want to add memory and cpus as soon as they appear
ATTR{[dmi/id]sys_vendor}!="Microsoft Corporation", GOTO="hyperv_hotadd_end"
ATTR{[dmi/id]product_name}!="Virtual Machine", GOTO="hyperv_hotadd_end"

# 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="hyperv_hotadd_end"

Whereas in xenial the file moved to /lib/udev/rules.d/40-vm-hotadd.rules and includes ATTR{[dmi/id]sys_vendor}=="Xen", GOTO="vm_hotadd_apply" which does trigger the bug.