Comment # 2 on bug 1213486 from Jan Kara

Well, this is not a functionality bug per se. Rather it is a functionality
which is not really supported and the patch adds proper error return instead of
resulting in rather random behavior. I'd be reluctant to actually backport the
commit to released versions of our distro as if accidentally some application
depends on the behavior, the update would break it. If the customer finds on
distro version update that something is broken, they are in much better setting
to fix their application to not depend on broken behavior.

So I will push the fix to the 6.4 based kernels we're going to ship with
SLE15-SP5 and ALP (in fact stable process is likely to pick it up for them) but
for older kernels this is IMO WONTFIX.