[$] A pair of memory-allocation improvements in 5.13

Among the many changes merged for 5.13 can be found performanceimprovements throughout the kernel. This work does not always stand outthe way that new features do, but it is vitally important for the future ofthe kernel overall. In the memory-management area, a couple oflong-running patch sets have finally made it into the mainline; theseprovide a bulk page-allocation interface andhuge-page mappings in the vmalloc() area.Both of these changes should make things faster, at least for someworkloads.