tree 6e0b4aa27aeb23303c60bdef88cff8dd80eaccb4
parent c08e611b7d0169b513e3b4515ffd51ac7f37f22c
author Christian Borntraeger <borntraeger@de.ibm.com> 1491768578 +0200
committer Martin Schwidefsky <schwidefsky@de.ibm.com> 1491975624 +0200

s390/mm: fix CMMA vs KSM vs others

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.

Cc: stable@vger.kernel.org
Signed-of-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>