Why does RHEL6 allocate a number of size-2097152 slabs on boot?

Issue

• Is the memory allocated to page_cgroup reserved solely for that use?
• In our stock RHEL6.0 build, there is a sizable amount of memory allocated to 2048k slab objects (SUnreclaim in /proc/meminfo; size-2097152 in /proc/slabinfo).  On our boxes with 48GB memory this is 384 objects/768MB and on the 96GB boxes it is 768 objects/1.5GB.  Extrapolating from the 2 samples, it appears to be something on the order of 8 objects/16MB per 1GB of physical memory.  I would like to understand what/why this memory is being used.