Correct me if I'm wrong but the top command only monitors the memory usage of applications, not the memory usage dedicated to the kernel.
How would you go about monitoring usage of memory dedicated to the kernel?
The kernel exports this information via /proc/slabinfo. It's not very easy to read, so there's also a slabtop tool (from procps, which you probably have installed already).
This invocation is what I usually use, but check the man page to see what else it can do: