[$] High-granularity mappings for huge pages

The use of huge pages can make memory management more efficient in a number
of ways, but it can also impose costs in the form of internal fragmentation and
I/O amplification. At the 2023 Linux
Storage, Filesystem, Memory-Management and BPF Summit, James Houghton
ran a session on a scheme to get the best of both worlds: using huge pages
while maintaining base-page mappings within them.