[$] Improving the per-CPU memory allocator

There are many places in the kernel where performance can be improved by using per-CPU data. But, as it turns out, the kernel's allocator for per-CPU data has some performance problems of its own. Harry Yoo led a session in the memory-management track of the 2026 Linux Storage, Filesystem, Memory Management, and BPF Summit to explore ways to address those problems and accelerate the allocation and initialization of per-CPU data.