On Thu, May 27, 2021 at 07:08:09PM -0400, Felix Kuehling wrote:

From: Alex Sierra <redacted>

pages in device mapping refcounts are 1-based, instead
of 0-based. If refcount 1, means it can be freed.
This logic is not set for Generic memory type. Therefore,
its release is threated as a normal page, instead of
the callback device driver release it.

So we really need to stop this magic one off refcount.  We had a WIP
patchset to do that, and we need to finish that off instad of piling on
more hacks.