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

As the 2025 LinuxStorage, Filesystem, Memory-Management, and BPF Summit (LSFMM+BPF)approaches, the density of memory-management patches on the mailing listshas increased. Included among those are patches aimed at improving thereliability and performance of huge-page allocation, implementing pagepromotion on tiered-memory systems, adding a different approach todeduplicating memory, and replacing the BPF memory allocator. Read on foran overview of each.