centos man page for ksize

KSIZE(9)						    Memory Management in Linux							  KSIZE(9)

NAME
       ksize - get the actual amount of memory allocated for a given object

SYNOPSIS
       size_t ksize(const void * objp);

ARGUMENTS
       objp
	   Pointer to the object

DESCRIPTION
       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.

COPYRIGHT
Kernel Hackers Manual 3.10					     June 2014								  KSIZE(9)