Commit 1c343f7b authored by Christian Borntraeger's avatar Christian Borntraeger Committed by Martin Schwidefsky

KVM: s390/mm: Fix CMMA reset during reboot

commit 1e133ab2 ("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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Fixes: 1e133ab2 ("s390/mm: split arch/s390/mm/pgtable.c")
Cc: stable@vger.kernel.org # 4.6+
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 5edb5649
...@@ -437,7 +437,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr, ...@@ -437,7 +437,7 @@ void ptep_zap_unused(struct mm_struct *mm, unsigned long addr,
pgste = pgste_get_lock(ptep); pgste = pgste_get_lock(ptep);
pgstev = pgste_val(pgste); pgstev = pgste_val(pgste);
pte = *ptep; pte = *ptep;
if (pte_swap(pte) && if (!reset && pte_swap(pte) &&
((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED || ((pgstev & _PGSTE_GPS_USAGE_MASK) == _PGSTE_GPS_USAGE_UNUSED ||
(pgstev & _PGSTE_GPS_ZERO))) { (pgstev & _PGSTE_GPS_ZERO))) {
ptep_zap_swap_entry(mm, pte_to_swp_entry(pte)); ptep_zap_swap_entry(mm, pte_to_swp_entry(pte));
......
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