This is a note to let you know that I've just added the patch titled s390/mm: fix CMMA vs KSM vs others to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: s390-mm-fix-cmma-vs-ksm-vs-others.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From a8f60d1fadf7b8b54449fcc9d6b15248917478ba Mon Sep 17 00:00:00 2001 From: Christian Borntraeger <borntraeger@xxxxxxxxxx> Date: Sun, 9 Apr 2017 22:09:38 +0200 Subject: s390/mm: fix CMMA vs KSM vs others From: Christian Borntraeger <borntraeger@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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 @@ -1029,6 +1029,8 @@ int get_guest_storage_key(struct mm_stru 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 Patches currently in stable-queue which might be from borntraeger@xxxxxxxxxx are queue-4.9/s390-mm-fix-cmma-vs-ksm-vs-others.patch