s390/mm: missing pte for gmap_ipte_notify should trigger a VM_BUG

After fixup_user_fault does not fail we have a writeable pte.
That pte might transform but it should not vanish.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index b1871d3..9c8a6dd 100644 (file)
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -752,8 +752,7 @@ int gmap_ipte_notify(struct gmap *gmap, unsigned long gaddr, unsigned long len)
                        break;
                /* Walk the process page table, lock and get pte pointer */
                ptep = get_locked_pte(gmap->mm, addr, &ptl);
-               if (unlikely(!ptep))
-                       continue;
+               VM_BUG_ON(!ptep);
                /* Set notification bit in the pgste of the pte */
                entry = *ptep;
                if ((pte_val(entry) & (_PAGE_INVALID | _PAGE_PROTECT)) == 0) {