2 files changed, 122 insertions, 0 deletions

diff --git a/include/linux/memory.h b/include/linux/memory.h
index ec376e482abb..33f0ff0cf634 100644
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -83,10 +83,14 @@ extern int memory_notify(unsigned long val, void *v);
 
 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 
+#ifdef CONFIG_MEMORY_HOTPLUG
 #define hotplug_memory_notifier(fn, pri) {                      \
         static struct notifier_block fn##_mem_nb =              \
                 { .notifier_call = fn, .priority = pri };       \
         register_memory_notifier(&fn##_mem_nb);                 \
 }
+#else
+#define hotplug_memory_notifier(fn, pri) do { } while (0)
+#endif
 
 #endif /* _LINUX_MEMORY_H_ */
diff --git a/mm/slub.c b/mm/slub.c
index e29a42988c78..aac1dd3c657d 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -20,6 +20,7 @@
 #include <linux/mempolicy.h>
 #include <linux/ctype.h>
 #include <linux/kallsyms.h>
+#include <linux/memory.h>
 
 /*
  * Lock order:
@@ -2694,6 +2695,121 @@ int kmem_cache_shrink(struct kmem_cache *s)
 }
 EXPORT_SYMBOL(kmem_cache_shrink);
 
+#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
+static int slab_mem_going_offline_callback(void *arg)
+{
+        struct kmem_cache *s;
+
+        down_read(&slub_lock);
+        list_for_each_entry(s, &slab_caches, list)
+                kmem_cache_shrink(s);
+        up_read(&slub_lock);
+
+        return 0;
+}
+
+static void slab_mem_offline_callback(void *arg)
+{
+        struct kmem_cache_node *n;
+        struct kmem_cache *s;
+        struct memory_notify *marg = arg;
+        int offline_node;
+
+        offline_node = marg->status_change_nid;
+
+        /*
+         * If the node still has available memory. we need kmem_cache_node
+         * for it yet.
+         */
+        if (offline_node < 0)
+                return;
+
+        down_read(&slub_lock);
+        list_for_each_entry(s, &slab_caches, list) {
+                n = get_node(s, offline_node);
+                if (n) {
+                        /*
+                         * if n->nr_slabs > 0, slabs still exist on the node
+                         * that is going down. We were unable to free them,
+                         * and offline_pages() function shoudn't call this
+                         * callback. So, we must fail.
+                         */
+                        BUG_ON(atomic_read(&n->nr_slabs));
+
+                        s->node[offline_node] = NULL;
+                        kmem_cache_free(kmalloc_caches, n);
+                }
+        }
+        up_read(&slub_lock);
+}
+
+static int slab_mem_going_online_callback(void *arg)
+{
+        struct kmem_cache_node *n;
+        struct kmem_cache *s;
+        struct memory_notify *marg = arg;
+        int nid = marg->status_change_nid;
+        int ret = 0;
+
+        /*
+         * If the node's memory is already available, then kmem_cache_node is
+         * already created. Nothing to do.
+         */
+        if (nid < 0)
+                return 0;
+
+        /*
+         * We are bringing a node online. No memory is availabe yet. We must
+         * allocate a kmem_cache_node structure in order to bring the node
+         * online.
+         */
+        down_read(&slub_lock);
+        list_for_each_entry(s, &slab_caches, list) {
+                /*
+                 * XXX: kmem_cache_alloc_node will fallback to other nodes
+                 *      since memory is not yet available from the node that
+                 *      is brought up.
+                 */
+                n = kmem_cache_alloc(kmalloc_caches, GFP_KERNEL);
+                if (!n) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+                init_kmem_cache_node(n);
+                s->node[nid] = n;
+        }
+out:
+        up_read(&slub_lock);
+        return ret;
+}
+
+static int slab_memory_callback(struct notifier_block *self,
+                                unsigned long action, void *arg)
+{
+        int ret = 0;
+
+        switch (action) {
+        case MEM_GOING_ONLINE:
+                ret = slab_mem_going_online_callback(arg);
+                break;
+        case MEM_GOING_OFFLINE:
+                ret = slab_mem_going_offline_callback(arg);
+                break;
+        case MEM_OFFLINE:
+        case MEM_CANCEL_ONLINE:
+                slab_mem_offline_callback(arg);
+                break;
+        case MEM_ONLINE:
+        case MEM_CANCEL_OFFLINE:
+                break;
+        }
+
+        ret = notifier_from_errno(ret);
+        return ret;
+}
+
+#endif /* CONFIG_MEMORY_HOTPLUG */
+
 /********************************************************************
  *                      Basic setup of slabs
  *******************************************************************/
@@ -2715,6 +2831,8 @@ void __init kmem_cache_init(void)
                 sizeof(struct kmem_cache_node), GFP_KERNEL);
         kmalloc_caches[0].refcount = -1;
         caches++;
+
+        hotplug_memory_notifier(slab_memory_callback, 1);
 #endif
 
         /* Able to allocate the per node structures */