Validation of memory allocated through kmalloc

Hi,
Is there some kernel api to validate memory allocated using kmalloc.
Suppose, I allocate some memory using kmalloc and at a later point of execution
I would like to validate if the memory allocated is not possibly freed by some other thread.

Pls suggest a patch/pointers if any.
I also noticed a commented 'CONFIG_DEBUG_MALLOC' config option  (2.4.3 source),
It doesn't seem to be functional.  Any pointers towards the history behind
it would also be helpful.

Thanks in advance,
Kiran