s390/mm: correct pgtable_bytes on page table downgrade

The downgrade of a page table from 3 levels to 2 levels for a 31-bit compat
process removes a pmd table which has to be counted against pgtable_bytes.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index 814f26520aa2..6791562779ee 100644
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -131,6 +131,7 @@ void crst_table_downgrade(struct mm_struct *mm)
         }
 
         pgd = mm->pgd;
+        mm_dec_nr_pmds(mm);
         mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
         mm->context.asce_limit = _REGION3_SIZE;
         mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |