lkml.org 
[lkml]   [2017]   [Jul]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Date
Subject[PATCH 3.16 147/178] s390/mm: fix CMMA vs KSM vs others
3.16.46-rc1 review patch.  If anyone has any objections, please let me know.

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

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

commit a8f60d1fadf7b8b54449fcc9d6b15248917478ba upstream.

On heavy paging with KSM I see guest data corruption. Turns out that
KSM will add pages to its tree, where the mapping return true for
pte_unused (or might become as such later). KSM will unmap such pages
and reinstantiate with different attributes (e.g. write protected or
special, e.g. in replace_page or write_protect_page)). This uncovered
a bug in our pagetable handling: We must remove the unused flag as
soon as an entry becomes present again.

Signed-of-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/s390/include/asm/pgtable.h | 2 ++
1 file changed, 2 insertions(+)

--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -868,6 +868,8 @@ static inline void set_pte_at(struct mm_
{
pgste_t pgste;

+ if (pte_present(entry))
+ pte_val(entry) &= ~_PAGE_UNUSED;
if (mm_has_pgste(mm)) {
pgste = pgste_get_lock(ptep);
pgste_val(pgste) &= ~_PGSTE_GPS_ZERO;
\
 
 \ /
  Last update: 2017-07-16 16:08    [W:0.690 / U:2.964 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site