ksize — get the actual amount of memory allocated for a given object
| size_t ksize ( | const void * objp ); | 
   kmalloc may internally round up allocations and return more memory
   than requested. ksize can be used to determine the actual amount of
   memory allocated. The caller may use this additional memory, even though
   a smaller amount of memory was initially specified with the kmalloc call.
   The caller must guarantee that objp points to a valid object previously
   allocated with either kmalloc or kmem_cache_alloc. The object
   must not be freed during the duration of the call.