mm/hmm: remove hugetlbfs check in hmm_vma_walk_pmd

walk_page_range() will only call hmm_vma_walk_hugetlb_entry() for
hugetlbfs pages and doesn't call hmm_vma_walk_pmd() in this case.

Therefore, it is safe to remove the check for vma->vm_flags & VM_HUGETLB
in hmm_vma_walk_pmd().

Link: https://lore.kernel.org/r/20190726005650.2566-7-rcampbell@nvidia.comSigned-off-by: Ralph Campbell <rcampbell@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

mm/hmm.c

@@ -630,9 +630,6 @@ static int hmm_vma_walk_pmd(pmd_t *pmdp,
 	if (pmd_none(pmd))
 		return hmm_vma_walk_hole(start, end, walk);
 
-	if (pmd_huge(pmd) && (range->vma->vm_flags & VM_HUGETLB))
-		return hmm_pfns_bad(start, end, walk);
-
 	if (thp_migration_supported() && is_pmd_migration_entry(pmd)) {
 		bool fault, write_fault;
 		unsigned long npages;