When file-backed memory is configured, it is the only "memory" reported
by nova and used by instances, with RAM used in caching capacity. We
should be warning users of this and insisting they explicitly configure
the '[DEFAULT] reserved_host_memory_mb' config option to 0. However,
doing so now would be breaking change. Instead, start logging a warning
instead, failing only for the truly broken combination of reserving more
file-backed memory than we have allocated.
Change-Id: I9619338ad0f60253b628d96543f8ce3ac86242e3
Signed-off-by: Stephen Finucane <stephenfin@redhat.com>
Closes-Bug: #1882821
3b99747b42