Subject: slub numa: Fix rare allocation from unexpected node The network developers have seen sporadic allocations resulting in objects coming from unexpected NUMA nodes despite asking for objects from a specific node. This is due to get_partial() calling get_any_partial() if partial slabs are exhausted for a node even if a node was specified and therefore one would expect allocations only from the specified node. get_any_partial() sporadically may return a slab from a foreign node to gradually reduce the size of partial lists on remote nodes and thereby reduce total memory use for a slab cache. The behavior is controlled by the remote_defrag_ratio of each cache. Strictly speaking this is permitted behavior since __GFP_THISNODE was not specified for the allocation but it is certain surprising. This patch makes sure that the remote defrag behavior only occurs if no node was specified. Signed-off-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/mm/slub.c =================================================================== --- linux-2.6.orig/mm/slub.c 2010-07-23 09:24:11.000000000 -0500 +++ linux-2.6/mm/slub.c 2010-07-23 09:25:15.000000000 -0500 @@ -1390,7 +1390,7 @@ static struct page *get_partial(struct k int searchnode = (node == -1) ? numa_node_id() : node; page = get_partial_node(get_node(s, searchnode)); - if (page || (flags & __GFP_THISNODE)) + if (page || node != -1) return page; return get_any_partial(s, flags); -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>