Comment # 41 on bug 1220569 from Takashi Iwai

(In reply to Roger Whittaker from comment #40)
> Installing the last (Tumbleweed) kernel has probably messed up the system
> because it forced the usr-merge thing.

Ah, that's bad.  You should have installed the kernel from OBS
Kernel:stable:Backport repo instead, which was built for SLE/Leap.

>  But I can rebuild it and test > 6.4
> from your repositories if it helps.

Yes, please check which upstream kernel started breaking.

It's already good to know that SLE15-SP6/Leap kernel breaks, but it has way too
many (over 19000!) changes since the upstream 6.4 code.