[$] Making slab-allocated objects movable

Memory fragmentation is a constant problem for memory-managementsubsystems. Over the years, considerable effort has been put intoreducing fragmentation in the Linux kernel, but almost all of that work hasbeen focused on memory management at the page level. The slab allocators,which (mostly) manage memory in chunks of less than the page size, haveseen less attention, but fragmentation at this level can create problems throughout the system. The slabmovable objects patch set posted by Tobin Harding is an attempt toimprove this situation by making it possible for the kernel to activelydefragment slab pages by moving objects around.