[$] MM medley: huge page allocation, page promotion, KSM, and BPF

As the 2025 Linux
Storage, Filesystem, Memory-Management, and BPF Summit (LSFMM+BPF)
approaches, the density of memory-management patches on the mailing lists
has increased. Included among those are patches aimed at improving the
reliability and performance of huge-page allocation, implementing page
promotion on tiered-memory systems, adding a different approach to
deduplicating memory, and replacing the BPF memory allocator. Read on for
an overview of each.