mm/sparse.c: use kvmalloc/kvfree to alloc/free memmap for the classic sparse

struct page * __meminit populate_section_memmap(unsigned long pfn,

		unsigned long nr_pages, int nid, struct vmem_altmap *altmap)

{

	struct page *page, *ret;

	unsigned long memmap_size = sizeof(struct page) * PAGES_PER_SECTION;

	page = alloc_pages(GFP_KERNEL|__GFP_NOWARN, get_order(memmap_size));

	if (page)

		goto got_map_page;

	ret = vmalloc(memmap_size);

	if (ret)

		goto got_map_ptr;

	return NULL;

got_map_page:

	ret = (struct page *)pfn_to_kaddr(page_to_pfn(page));

got_map_ptr:

	return ret;

	return kvmalloc(array_size(sizeof(struct page),

				   PAGES_PER_SECTION), GFP_KERNEL);

}

static void depopulate_section_memmap(unsigned long pfn, unsigned long nr_pages,

		struct vmem_altmap *altmap)

{

	struct page *memmap = pfn_to_page(pfn);

	if (is_vmalloc_addr(memmap))

		vfree(memmap);

	else

		free_pages((unsigned long)memmap,

			   get_order(sizeof(struct page) * PAGES_PER_SECTION));

	kvfree(pfn_to_page(pfn));

}

static void free_map_bootmem(struct page *memmap)