mount namespaces broken since 18.10 upgrade

[Bjoern Franke]

Hi,

I upgraded my Thinkpad X230 from 18.04 to 18.10 and afterwards several
services fail:

 UNIT                                                  LOAD   ACTIVE SUB
   DESCRIPTION
● geoclue.service                                       loaded failed
failed Location Lookup Service
● systemd-swap.service                                  loaded failed
failed Manage swap spaces on zram, files and partitions.
● systemd-timesyncd.service                             loaded failed
failed Network Time Synchronization
● upower.service                                        loaded failed
failed Daemon for power management
● user-runtime-dir at 1000.service                         loaded failed
failed /run/user/1000 mount wrapper
● user at 1000.service                                     loaded failed
failed User Manager for UID 1000

They fail because they try to create a mounted namespace:
Okt 22 14:12:42 x230 systemd[4934]: upower.service: Failed to set up
mount namespacing: Bad address
Okt 22 14:12:42 x230 systemd[4934]: upower.service: Failed at step
NAMESPACE spawning /usr/lib/upower/upowerd: Bad address

Also a manual mount of a namespace fails:

sudo mount -v --make-shared /tmp/foo
mount: /tmp/foo: mount(2) system call failed: Bad address.

I have no clue why this happens, also using an old bionic kernel shows
this issue. The kernel commandline is the usual "quiet squash", so mount
namespaces are not disabled manually.

Best regards
bjo