[S390] memory leak with RCU_TABLE_FREE

The rcu page table free code uses a couple of bits in the page table
pointer passed to tlb_remove_table to discern the different page table
types. __tlb_remove_table extracts the type with an incorrect mask which
leads to memory leaks. The correct mask is ((FRAG_MASK << 4) | FRAG_MASK).

Cc: stable@kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 5d56c2b95b14..529a08838376 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -662,8 +662,9 @@ void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table)
 
 void __tlb_remove_table(void *_table)
 {
-        void *table = (void *)((unsigned long) _table & PAGE_MASK);
-        unsigned type = (unsigned long) _table & ~PAGE_MASK;
+        const unsigned long mask = (FRAG_MASK << 4) | FRAG_MASK;
+        void *table = (void *)((unsigned long) _table & ~mask);
+        unsigned type = (unsigned long) _table & mask;
 
         if (type)
                 __page_table_free_rcu(table, type);