[RFC PATCH 2/4] slub: fallback to node_to_mem_node() node if allocating on memoryless node

[Nishanth Aravamudan]

From: Joonsoo Kim <iamjoonsoo.kim at lge.com>

Update the SLUB code to search for partial slabs on the nearest node
with memory in the presence of memoryless nodes. Additionally, do not
consider it to be an ALLOC_NODE_MISMATCH (and deactivate the slab) when
a memoryless-node specified allocation goes off-node.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim at lge.com>
Signed-off-by: Nishanth Aravamudan <nacc at linux.vnet.ibm.com>
    
---
v1 -> v2 (Nishanth):
  Add commit message
  Clean-up conditions in get_partial()

diff --git a/mm/slub.c b/mm/slub.c
index 3e8afcc07a76..497fdfed2f01 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1699,7 +1699,12 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
 		struct kmem_cache_cpu *c)
 {
 	void *object;
-	int searchnode = (node == NUMA_NO_NODE) ? numa_mem_id() : node;
+	int searchnode = node;
+
+	if (node == NUMA_NO_NODE)
+		searchnode = numa_mem_id();
+	else if (!node_present_pages(node))
+		searchnode = node_to_mem_node(node);
 
 	object = get_partial_node(s, get_node(s, searchnode), c, flags);
 	if (object || node != NUMA_NO_NODE)
@@ -2280,11 +2285,18 @@ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
 redo:
 
 	if (unlikely(!node_match(page, node))) {
-		stat(s, ALLOC_NODE_MISMATCH);
-		deactivate_slab(s, page, c->freelist);
-		c->page = NULL;
-		c->freelist = NULL;
-		goto new_slab;
+		int searchnode = node;
+
+		if (node != NUMA_NO_NODE && !node_present_pages(node))
+			searchnode = node_to_mem_node(node);
+
+		if (unlikely(!node_match(page, searchnode))) {
+			stat(s, ALLOC_NODE_MISMATCH);
+			deactivate_slab(s, page, c->freelist);
+			c->page = NULL;
+			c->freelist = NULL;
+			goto new_slab;
+		}
 	}
 
 	/*