From e4efdb90b85010de91ea1a3dabc59b70d1b060fc Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Mon, 13 Jun 2016 13:14:56 +0200 Subject: [PATCH] KVM: s390/mm: Fix CMMA reset during reboot commit 1a37d6c72f2 ("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 Fixes: 1a37d6c72f2 ("s390/mm: split arch/s390/mm/pgtable.c") Cc: stable@vger.kernel.org # 4.6+ Signed-off-by: Martin Schwidefsky --- arch/s390/mm/pgtable.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 4324b87f93982..9f0ce0e6eeb48 100644 --- 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)); -- 2.39.5