[$] The transparent huge page shrinker

Huge pages are a mechanism implemented by the CPU that allows the managementof memory in larger chunks. Use of huge pages can increase performancesignificantly, which is why the kernel has a "transparent huge page"mechanism to try to create them when possible. But a huge page will onlybe helpful if most of the memory contained within it is actually in use;otherwise it is just an expensive waste of memory. This patchset from Alexander Zhu implements a mechanism to detect underutilizedhuge pages and recover that wasted memory for other uses.