mm/huge_memory: convert do_huge_pmd_anonymous_page() to use vma_alloc_folio()

Remove the use of this old API, eliminating a call to
prep_transhuge_page().

Link: https://lkml.kernel.org/r/20220504182857.4013401-3-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/huge_memory.c

@@ -726,7 +726,7 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 {
 	struct vm_area_struct *vma = vmf->vma;
 	gfp_t gfp;
-	struct page *page;
+	struct folio *folio;
 	unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
 
 	if (!transhuge_vma_suitable(vma, haddr))
@@ -775,13 +775,12 @@ vm_fault_t do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 		return ret;
 	}
 	gfp = vma_thp_gfp_mask(vma);
-	page = alloc_hugepage_vma(gfp, vma, haddr, HPAGE_PMD_ORDER);
-	if (unlikely(!page)) {
+	folio = vma_alloc_folio(gfp, HPAGE_PMD_ORDER, vma, haddr, true);
+	if (unlikely(!folio)) {
 		count_vm_event(THP_FAULT_FALLBACK);
 		return VM_FAULT_FALLBACK;
 	}
-	prep_transhuge_page(page);
-	return __do_huge_pmd_anonymous_page(vmf, page, gfp);
+	return __do_huge_pmd_anonymous_page(vmf, &folio->page, gfp);
 }
 
 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,