diff options
| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2017-04-09 22:09:38 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-30 05:49:13 +0200 |
| commit | 2ac3f8b5b877114d8324ef038d145aaaf86f37a2 (patch) | |
| tree | 4f7ec1c66a45217b0b77ac371e7bec0c690cdd55 /arch | |
| parent | 018a5fb662bdbf94874fb7c000fec6e9f00729ab (diff) | |
s390/mm: fix CMMA vs KSM vs others
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>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/include/asm/pgtable.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h index b0373b44b320..15fe9b538932 100644 --- 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_struct *mm, unsigned long addr, { 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; |