[$] Improving the per-CPU memory allocator

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