[$] Optimizing single-owner memory

The kernel's memory-management subsystem is optimized for the sharing ofresources to the greatest extent possible. But, as Pasha Tatashin pointedout during a memory-management session at the 2023 Linux Storage, Filesystem,Memory-Management and BPF Summit, a lot of memory has a single ownerand will never be shared. He presented some ideas for optimizing themanagement of that memory to a somewhat skeptical crowd.