This option enables tracing of dynamically allocated kernel memory
to see if memory is used before it has been given an initial value.
Be aware that this requires half of your memory for bookkeeping and
will insert extra code at *every* read and write to tracked memory
thus slow down the kernel code (but user code is unaffected).

The kernel may be started with kmemcheck=0 or kmemcheck=1 to disable
or enable kmemcheck at boot-time. If the kernel is started with
kmemcheck=0, the large memory and CPU overhead is not incurred.

source code:

mm/kmemcheck.c