memory leak with RCU_TABLE_FREE

BugLink: http://bugs.launchpad.net/bugs/890952

commit e73b7fffe487c315fd1a4fa22282e3362b440a06 upstream.

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).

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 37a23c22370..458893f5f6b 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -291,8 +291,9 @@ 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);