KVM: s390/mm: Fix CMMA reset during reboot

commit 1e133ab ("s390/mm: split arch/s390/mm/pgtable.c") factored out the page table handling code from __gmap_zap and __s390_reset_cmma into ptep_zap_unused and added a simple flag that tells which one of the function (reset or not) is to be made. This also changed the behaviour, as it also zaps unused page table entries on reset. Turns out that this is wrong as s390_reset_cmma uses the page walker, which DOES NOT take the ptl lock. The most simple fix is to not do the zapping part on reset (which uses the walker) Signed-off-by: Christian Borntraeger <[email protected]> Fixes: 1e133ab ("s390/mm: split arch/s390/mm/pgtable.c") Cc: [email protected] # 4.6+ Signed-off-by: Martin Schwidefsky <[email protected]>
matt-auld · Jun 13, 2016 · 1c343f7 · 1c343f7
1 parent 5edb564
commit 1c343f7
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
@@ -437,7 +437,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
 	pgste = pgste_get_lock(ptep);
 	pgstev = pgste_val(pgste);
 	pte = *ptep;
-	if (pte_swap(pte) &&
+	if (!reset && pte_swap(pte) &&
 	    ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED ||
 	     (pgstev & _PGSTE_GPS_ZERO))) {
 		ptep_zap_swap_entry(mm, pte_to_swp_entry(pte));