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authorChristian Borntraeger <borntraeger@de.ibm.com>2017-04-09 22:09:38 +0200
committerMartin Schwidefsky <schwidefsky@de.ibm.com>2017-04-12 07:40:24 +0200
commita8f60d1fadf7b8b54449fcc9d6b15248917478ba (patch)
tree6e0b4aa27aeb23303c60bdef88cff8dd80eaccb4 /arch/s390
parentc08e611b7d0169b513e3b4515ffd51ac7f37f22c (diff)
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>
Diffstat (limited to 'arch/s390')
-rw-r--r--arch/s390/include/asm/pgtable.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index 93e37b12e882..ecec682bb516 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -1051,6 +1051,8 @@ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
{
if (!MACHINE_HAS_NX)
pte_val(entry) &= ~_PAGE_NOEXEC;
+ if (pte_present(entry))
+ pte_val(entry) &= ~_PAGE_UNUSED;
if (mm_has_pgste(mm))
ptep_set_pte_at(mm, addr, ptep, entry);
else