Hugetlb gigantic page and dynamic allocation

Hi,

I was looking at this w.r.t a recent patch series and wondering whether the usage of alloc_contig_page is correct there. We do

static int __alloc_gigantic_page(unsigned long start_pfn,
unsigned long nr_pages)

{
	unsigned long end_pfn = start_pfn + nr_pages;
	return alloc_contig_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
}

That implies, if we fail in certain case we will mark the page block migrate type MIGRATE_MOVABLE . Do we want to do that in all case ? What if the start_pfn was convering a page block of MIGRATE_CMA type ? Should we skip pageblock with MIGRATE_CMA type when trying to allocate gigantic huge page ?