Patch "s390/mm: make pmdp_invalidate() do invalidation only" has been added to the 4.13-stable tree

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 4.13-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-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Gerald Schaefer <[email protected]>
Date: Mon, 18 Sep 2017 16:10:35 +0200
Subject: s390/mm: make pmdp_invalidate() do invalidation only

From: Gerald Schaefer <[email protected]>

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.

---
 arch/s390/include/asm/pgtable.h |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

@@ -1462,7 +1462,9 @@ 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_EMPTY));
+	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 [email protected] are

queue-4.13/s390-mm-make-pmdp_invalidate-do-invalidation-only.patch queue-4.13/s390-mm-fix-write-access-check-in-gup_huge_pmd.patch