gistfile1.txt

#include <linux/slab.h>

void *ptr1;
void *ptr2;

int init_module()
{

	ptr1 = kmalloc( (size_t)255,GFP_KERNEL);
	ptr2 = kmalloc( (size_t)255,GFP_KERNEL);
	printk("Ksize: %d\n", (int) ksize(ptr1));
	printk("location ptr1: %p\n",  ptr1);
	printk("location ptr2: %p\n",  ptr2);

    return 0;
}

void cleanup_module()
{
	kfree(ptr1);
	kfree(ptr2);
    return;
}

[root@localhost test]# make test
rmmod test && insmod test.ko
Ksize: 256
location ptr1: ffff880037b55b80
location ptr2: ffff880037f3fdc0

>>> 0xffff880037f3fdc0 - 0xffff880037b55b80
4104768L
>>> hex( 0xffff880037f3fdc0 - 0xffff880037b55b80 )
'0x3ea240L'