Description of problem:
From: Rik van Riel <riel@redhat.com>
On small systems, the extra memory used by the anti-fragmentation
memory reserve and simply because huge pages are smaller than large
pages can easily outweigh the benefits of less TLB misses.

In case of the crashdump kernel, OOMs have been observed due to
the anti-fragmentation memory reserve taking up a large fraction
of the crashdump image.

This patch disables transparent hugepages on systems with less
than 1GB of RAM, but the hugepage subsystem is fully initialized
so administrators can enable THP through /sys if desired.