Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a8f60d1f authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Martin Schwidefsky
Browse files

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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent c08e611b

arch/s390/include/asm/pgtable.h

+2 −0
Original line number Diff line number Diff line
@@ -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