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>

1 files changed, 1 insertions, 2 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index b1871d39e46e..9c8a6dd8a49c 100644
--- 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) {