diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 02d15c8dc92e..8947451ae021 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -336,12 +336,11 @@ static int gmap_alloc_table(struct gmap *gmap, unsigned long *table,
 static unsigned long __gmap_segment_gaddr(unsigned long *entry)
 {
 	struct page *page;
-	unsigned long offset, mask;
+	unsigned long offset;
 
 	offset = (unsigned long) entry / sizeof(unsigned long);
 	offset = (offset & (PTRS_PER_PMD - 1)) * PMD_SIZE;
-	mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
-	page = virt_to_page((void *)((unsigned long) entry & mask));
+	page = pmd_pgtable_page((pmd_t *) entry);
 	return page->index + offset;
 }
 
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 2c73dc112ffc..8df5cae69c80 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2510,7 +2510,7 @@ static inline void pgtable_pte_page_dtor(struct page *page)
 
 #if USE_SPLIT_PMD_PTLOCKS
 
-static struct page *pmd_pgtable_page(pmd_t *pmd)
+static inline struct page *pmd_pgtable_page(pmd_t *pmd)
 {
 	unsigned long mask = ~(PTRS_PER_PMD * sizeof(pmd_t) - 1);
 	return virt_to_page((void *)((unsigned long) pmd & mask));