Re: [PATCH] slab: fix for_each_kmem_cache_node

Re: [PATCH] slab: fix for_each_kmem_cache_node

[Mikulas Patocka]

On Thu, 11 Sep 2014, Andrew Morton wrote:

> On Mon, 8 Sep 2014 09:16:34 -0500 (CDT) Christoph Lameter <cl@linux.com> wrote:
> 
> > 
> > Acked-by: Christoph Lameter <cl@linux.com>
> 
> I suspect the original patch got eaten by the linux-foundation.org DNS
> outage, and whoever started this thread didn't cc any mailing lists. 
> So I have no patch and no way of finding it.
> 
> Full resend with appropriate cc's please, after adding all the
> acked-bys and reviewed-bys.

This patch fixes a bug (discovered with kmemcheck) in
for_each_kmem_cache_node. The for loop reads the array "node" before
verifying that the index is within the range. This results in kmemcheck
warning.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-2.6/mm/slab.h
===================================================================
--- linux-2.6.orig/mm/slab.h	2014-09-04 23:04:31.000000000 +0200
+++ linux-2.6/mm/slab.h	2014-09-04 23:23:37.000000000 +0200
@@ -303,8 +303,8 @@ static inline struct kmem_cache_node *ge
  * a kmem_cache_node structure allocated (which is true for all online nodes)
  */
 #define for_each_kmem_cache_node(__s, __node, __n) \
-	for (__node = 0; __n = get_node(__s, __node), __node < nr_node_ids; __node++) \
-		 if (__n)
+	for (__node = 0; __node < nr_node_ids; __node++) \
+		 if ((__n = get_node(__s, __node)))
 
 #endif