Comment # 8 on bug 1231578 from Takashi Iwai

Thanks for quick testing!

So the likely cause seems to be either in the PM core change or in the storage
change.

To be sure, could you try the latest kernel in OBS Kernel:SLE15-SP5 repo and
verify that the problem still persists?
  http://download.opensuse.org/repositories/Kernel:/SLE15-SP5/pool/

Meanwhile, I'm building a test kernel with a few revers of the PM core change
from SLE15-SP5 branch.  It's being built in OBS home:tiwai:bsc1231578 repo.
Once after the build finishes (takes an hour or so), it'll appear at
  http://download.opensuse.org/repositories/home:/tiwai:/bsc1231578/pool/

Please give it a try, too.

BTW, when you install many kernels, old ones are purged automatically.  You can
edit /etc/zypp/zypp.conf and increase the number of installable kernels there,
e.g. set the line to:
  multiversion.kernels = latest,latest-1,latest-2,latest-3,running