2.6.30-stable review patch. If anyone has any objections, please let us know. ------------------ From: Bo Liu commit 7f9cfb31030737a7fc9a1cbca3fd01bec184c849 upstream. If node_load[] is cleared everytime build_zonelists() is called,node_load[] will have no help to find the next node that should appear in the given node's fallback list. Because of the bug, zonelist's node_order is not calculated as expected. This bug affects on big machine, which has asynmetric node distance. [synmetric NUMA's node distance] 0 1 2 0 10 12 12 1 12 10 12 2 12 12 10 [asynmetric NUMA's node distance] 0 1 2 0 10 12 20 1 12 10 14 2 20 14 10 This (my bug) is very old but no one has reported this for a long time. Maybe because the number of asynmetric NUMA is very small and they use cpuset for customizing node memory allocation fallback. [akpm@linux-foundation.org: fix CONFIG_NUMA=n build] Signed-off-by: Bo Liu Reviewed-by: KAMEZAWA Hiroyuki Cc: Mel Gorman Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2342,7 +2342,6 @@ static void build_zonelists(pg_data_t *p prev_node = local_node; nodes_clear(used_mask); - memset(node_load, 0, sizeof(node_load)); memset(node_order, 0, sizeof(node_order)); j = 0; @@ -2451,6 +2450,9 @@ static int __build_all_zonelists(void *d { int nid; +#ifdef CONFIG_NUMA + memset(node_load, 0, sizeof(node_load)); +#endif for_each_online_node(nid) { pg_data_t *pgdat = NODE_DATA(nid); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/