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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2017-04-09 22:09:38 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2017-07-18 18:40:34 +0100 |
| commit | f0e51b233eae4a86e143136e770e2934dac0ca18 (patch) | |
| tree | ab3c63fe2f69652fcb1f0b7d644dd52d21784c3d /arch | |
| parent | ac27a8bff23b37444c3489829dba7f0e11bbad1f (diff) | |
| download | linux-stable-f0e51b233eae4a86e143136e770e2934dac0ca18.tar.gz linux-stable-f0e51b233eae4a86e143136e770e2934dac0ca18.tar.bz2 linux-stable-f0e51b233eae4a86e143136e770e2934dac0ca18.zip | |
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>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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 8904e1282562..589f9c65416a 100644 --- 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_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; |