size_t __ksize(const void *object)
{
	struct page *page;

	if (unlikely(object == ZERO_SIZE_PTR))
		return 0;

	page = virt_to_head_page(object);

	if (unlikely(!PageSlab(page))) {
		WARN_ON(!PageCompound(page));
		return page_size(page);
	}

	return slab_ksize(page->slab_cache);
}