Comment # 32 on bug 1159882 from Michal Hocko

(In reply to Robert Delahunt from comment #30)
> Would you recommend the user (me) build or install one of the newer Linux
> kernels?  Do you have a specific version or tree that you would prefer I
> attempt to build or install?  Please let me know.  I may decide, some time
> today, to grab the latest stable Linux kernel and build it anyways, just for
> "fun," after my class today.

Running with the latest Linus' tree with the same config might tell us more.
There are certainly other changes in MM that might make a difference.
2c012a4ad1a2 ("mm: vmscan: scan anonymous pages on file refaults") can
definitely cause more swapping. I was not particularly happy about the patch
(https://lore.kernel.org/linux-mm/20190712071359.GN29483@dhcp22.suse.cz/).
Another option would be trying with that one reverted. Let me know if you need
a help with that.