[$] Using DAMON for proactive reclaim

The DAMON patch set was first covered here
in early 2020; this work, now in its
34th revision, enables the efficient collection of information about
memory-usage patterns on Linux systems. That data can then be used to
influence the kernel's memory-management subsystem; one possible way to do
that is to more aggressively reclaim memory that is not being used. To
that end, DAMON author SeongJae Park is proposing a
DAMON-based mechanism to perform user-controllable proactive reclaim.