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Groups > linux.kernel > #1632665
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 3.18 08/47] s390/mm: fix CMMA vs KSM vs others |
| Date | 2017-04-28 10:50 +0200 |
| Message-ID | <tB9Lb-4Zj-13@gated-at.bofh.it> (permalink) |
| References | <tB9Bv-4Ua-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
3.18-stable 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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
@@ -863,6 +863,8 @@ 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;
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[PATCH 3.18 08/47] s390/mm: fix CMMA vs KSM vs others Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-28 10:50 +0200
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