From: Dominik Dingel <dingel@linux.vnet.ibm.com>
Date: Wed, 15 Oct 2014 13:29:01 +0000 (+0200)
Subject: s390/mm: missing pte for gmap_ipte_notify should trigger a VM_BUG
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=6972cae523de728ad5e8dae01da4a631d98b874c;p=linux-beck.git

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 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) {