numa: fix slab_node(MPOL_BIND)

commit 800416f799e0723635ac2d720ad4449917a1481c upstream.

When a node contains only HighMem memory, slab_node(MPOL_BIND)
dereferences a NULL pointer.

[ This code seems to go back all the way to commit 19770b32609b: "mm:
  filter based on a nodemask as well as a gfp_mask".  Which was back in
  April 2008, and it got merged into 2.6.26.  - Linus ]

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index f969da5dd8a2136b92aab7e7c1a6ecc9083d6cb9..c1002c68d6178ccd879290ccb58d323c08355a35 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1588,7 +1588,7 @@ unsigned slab_node(struct mempolicy *policy)
                (void)first_zones_zonelist(zonelist, highest_zoneidx,
                                                        &policy->v.nodes,
                                                        &zone);
-               return zone->node;
+               return zone ? zone->node : numa_node_id();
        }
 
        default: