[$] Managing pages outside of the direct map

When Brendan Jackman proposed a session for the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit, his topic was ""a pagetable library for the kernel"". During the actual memory-management-track session, though, he stated that the idea had ""fizzled"" and he was going to cover related topics instead. What resulted was a session on ways to efficiently manage pages that are not present in the kernel's direct map.