mm/hugetlb: add folio_hstate()

Helper function to retrieve hstate information from a hugetlb folio.

Link: https://lkml.kernel.org/r/20220922154207.1575343-6-sidhartha.kumar@oracle.comSigned-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Colin Cross <ccross@google.com>
Cc: David Howells <dhowells@redhat.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/hugetlb.h

@@ -824,10 +824,15 @@ static inline pte_t arch_make_huge_pte(pte_t entry, unsigned int shift,
 }
 #endif
 
+static inline struct hstate *folio_hstate(struct folio *folio)
+{
+	VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio);
+	return size_to_hstate(folio_size(folio));
+}
+
 static inline struct hstate *page_hstate(struct page *page)
 {
-	VM_BUG_ON_PAGE(!PageHuge(page), page);
-	return size_to_hstate(page_size(page));
+	return folio_hstate(page_folio(page));
 }
 
 static inline unsigned hstate_index_to_shift(unsigned index)
@@ -1036,6 +1041,11 @@ static inline struct hstate *hstate_vma(struct vm_area_struct *vma)
 	return NULL;
 }
 
+static inline struct hstate *folio_hstate(struct folio *folio)
+{
+	return NULL;
+}
+
 static inline struct hstate *page_hstate(struct page *page)
 {
 	return NULL;

mm/migrate.c

@@ -1620,7 +1620,7 @@ struct page *alloc_migration_target(struct page *page, unsigned long private)
 		nid = folio_nid(folio);
 
 	if (folio_test_hugetlb(folio)) {
-		struct hstate *h = page_hstate(&folio->page);
+		struct hstate *h = folio_hstate(folio);
 
 		gfp_mask = htlb_modify_alloc_mask(h, gfp_mask);
 		return alloc_huge_page_nodemask(h, nid, mtc->nmask, gfp_mask);