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| author | Christian Borntraeger <borntraeger@de.ibm.com> | 2017-04-09 20:09:38 (GMT) |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-27 07:10:38 (GMT) |
| commit | 3d42ca46f47a4d3cd5abe465735227534c292aed (patch) | |
| tree | f1413576d42b24899b0ca4a9e1374f74df4cb530 /arch/s390 | |
| parent | f79ef57911ee598e0bfb7af1ab51413429a8f9d5 (diff) | |
| download | linux-3d42ca46f47a4d3cd5abe465735227534c292aed.tar.xz | |
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/s390')
| -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 0362cd5..0cea702 100644 --- a/arch/s390/include/asm/pgtable.h +++ b/arch/s390/include/asm/pgtable.h @@ -1029,6 +1029,8 @@ int get_guest_storage_key(struct mm_struct *mm, unsigned long addr, static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t entry) { + if (pte_present(entry)) + pte_val(entry) &= ~_PAGE_UNUSED; if (mm_has_pgste(mm)) ptep_set_pte_at(mm, addr, ptep, entry); else |