Patch "s390/mm: make pmdp_invalidate() do invalidation only" has been added to the 4.9-stable tree

Patch "s390/mm: make pmdp_invalidate() do invalidation only" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    s390/mm: make pmdp_invalidate() do invalidation only

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     s390-mm-make-pmdp_invalidate-do-invalidation-only.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 91c575b335766effa6103eba42a82aea560c365f Mon Sep 17 00:00:00 2001
From: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Date: Mon, 18 Sep 2017 16:10:35 +0200
Subject: s390/mm: make pmdp_invalidate() do invalidation only

From: Gerald Schaefer <gerald.schaefer@de.ibm.com>

commit 91c575b335766effa6103eba42a82aea560c365f upstream.

Commit 227be799c39a ("s390/mm: uninline pmdp_xxx functions from pgtable.h")
inadvertently changed the behavior of pmdp_invalidate(), so that it now
clears the pmd instead of just marking it as invalid. Fix this by restoring
the original behavior.

A possible impact of the misbehaving pmdp_invalidate() would be the
MADV_DONTNEED races (see commits ced10803 and 58ceeb6b), although we
should not have any negative impact on the related dirty/young flags,
since those flags are not set by the hardware on s390.

Fixes: 227be799c39a ("s390/mm: uninline pmdp_xxx functions from pgtable.h")
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/s390/include/asm/pgtable.h |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1359,7 +1359,9 @@ static inline pmd_t pmdp_huge_clear_flus
 static inline void pmdp_invalidate(struct vm_area_struct *vma,
 				   unsigned long addr, pmd_t *pmdp)
 {
-	pmdp_xchg_direct(vma->vm_mm, addr, pmdp, __pmd(_SEGMENT_ENTRY_INVALID));
+	pmd_t pmd = __pmd(pmd_val(*pmdp) | _SEGMENT_ENTRY_INVALID);
+
+	pmdp_xchg_direct(vma->vm_mm, addr, pmdp, pmd);
 }
 
 #define __HAVE_ARCH_PMDP_SET_WRPROTECT


Patches currently in stable-queue which might be from gerald.schaefer@de.ibm.com are

queue-4.9/s390-mm-make-pmdp_invalidate-do-invalidation-only.patch