1 files changed, 29 insertions, 9 deletions

diff --git a/mm/slab.c b/mm/slab.c
index 3318252f657f..bfd654c0ef41 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -869,6 +869,22 @@ static void __slab_error(const char *function, struct kmem_cache *cachep,
         dump_stack();
 }
 
+/*
+ * By default on NUMA we use alien caches to stage the freeing of
+ * objects allocated from other nodes. This causes massive memory
+ * inefficiencies when using fake NUMA setup to split memory into a
+ * large number of small nodes, so it can be disabled on the command
+ * line
+  */
+
+static int use_alien_caches __read_mostly = 1;
+static int __init noaliencache_setup(char *s)
+{
+        use_alien_caches = 0;
+        return 1;
+}
+__setup("noaliencache", noaliencache_setup);
+
 #ifdef CONFIG_NUMA
 /*
  * Special reaping functions for NUMA systems called from cache_reap().
@@ -1117,7 +1133,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
          * Make sure we are not freeing a object from another node to the array
          * cache on this cpu.
          */
-        if (likely(slabp->nodeid == node))
+        if (likely(slabp->nodeid == node) || unlikely(!use_alien_caches))
                 return 0;
 
         l3 = cachep->nodelists[node];
@@ -1195,7 +1211,7 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
                 list_for_each_entry(cachep, &cache_chain, next) {
                         struct array_cache *nc;
                         struct array_cache *shared;
-                        struct array_cache **alien;
+                        struct array_cache **alien = NULL;
 
                         nc = alloc_arraycache(node, cachep->limit,
                                                 cachep->batchcount);
@@ -1207,9 +1223,11 @@ static int __cpuinit cpuup_callback(struct notifier_block *nfb,
                         if (!shared)
                                 goto bad;
 
-                        alien = alloc_alien_cache(node, cachep->limit);
-                        if (!alien)
-                                goto bad;
+                        if (use_alien_caches) {
+                                alien = alloc_alien_cache(node, cachep->limit);
+                                if (!alien)
+                                        goto bad;
+                        }
                         cachep->array[cpu] = nc;
                         l3 = cachep->nodelists[node];
                         BUG_ON(!l3);
@@ -3590,13 +3608,15 @@ static int alloc_kmemlist(struct kmem_cache *cachep)
         int node;
         struct kmem_list3 *l3;
         struct array_cache *new_shared;
-        struct array_cache **new_alien;
+        struct array_cache **new_alien = NULL;
 
         for_each_online_node(node) {
 
-                new_alien = alloc_alien_cache(node, cachep->limit);
-                if (!new_alien)
-                        goto fail;
+                if (use_alien_caches) {
+                        new_alien = alloc_alien_cache(node, cachep->limit);
+                        if (!new_alien)
+                                goto fail;
+                }
 
                 new_shared = alloc_arraycache(node,
                                 cachep->shared*cachep->batchcount,