[PATCH 4.9 27/66] s390/mm: Fix cmma unused transfer from pgste into pte

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christian Borntraeger <borntrae...@de.ibm.com>

commit 0d6da872d3e4a60f43c295386d7ff9a4cdcd57e9 upstream.

The last pgtable rework silently disabled the CMMA unused state by
setting a local pte variable (a parameter) instead of propagating it
back into the caller. Fix it.

Fixes: ebde765c0e85 ("s390/mm: uninline ptep_xxx functions from pgtable.h")
Cc: Martin Schwidefsky <schwidef...@de.ibm.com>
Cc: Claudio Imbrenda <imbre...@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntrae...@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidef...@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/s390/mm/pgtable.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -202,7 +202,7 @@ static inline pgste_t ptep_xchg_start(st
        return pgste;
 }
 
-static inline void ptep_xchg_commit(struct mm_struct *mm,
+static inline pte_t ptep_xchg_commit(struct mm_struct *mm,
                                    unsigned long addr, pte_t *ptep,
                                    pgste_t pgste, pte_t old, pte_t new)
 {
@@ -220,6 +220,7 @@ static inline void ptep_xchg_commit(stru
        } else {
                *ptep = new;
        }
+       return old;
 }
 
 pte_t ptep_xchg_direct(struct mm_struct *mm, unsigned long addr,
@@ -231,7 +232,7 @@ pte_t ptep_xchg_direct(struct mm_struct
        preempt_disable();
        pgste = ptep_xchg_start(mm, addr, ptep);
        old = ptep_flush_direct(mm, addr, ptep);
-       ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
+       old = ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
        preempt_enable();
        return old;
 }
@@ -246,7 +247,7 @@ pte_t ptep_xchg_lazy(struct mm_struct *m
        preempt_disable();
        pgste = ptep_xchg_start(mm, addr, ptep);
        old = ptep_flush_lazy(mm, addr, ptep);
-       ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
+       old = ptep_xchg_commit(mm, addr, ptep, pgste, old, new);
        preempt_enable();
        return old;
 }