s390/mm,vmem: use 2GB frames for identity mapping

Use 2GB frames for indentity mapping if EDAT2 is
available to reduce TLB pressure.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c
index 00be01c..c7ec7c2 100644
--- a/arch/s390/mm/pageattr.c
+++ b/arch/s390/mm/pageattr.c
@@ -19,7 +19,7 @@
 	if (pgd_none(*pgdp))
 		return NULL;
 	pudp = pud_offset(pgdp, addr);
-	if (pud_none(*pudp))
+	if (pud_none(*pudp) || pud_large(*pudp))
 		return NULL;
 	pmdp = pmd_offset(pudp, addr);
 	if (pmd_none(*pmdp) || pmd_large(*pmdp))