order_to_size
unsigned long end = start + order_to_size(page->private);
while (this_order && left < order_to_size(this_order - 1))
if (order_to_size(this_order) < rq_size)
kmemleak_alloc(p, order_to_size(this_order), 1, GFP_NOIO);
entries_per_page = order_to_size(this_order) / rq_size;