[RFC V2 SLEB 06/14] SLUB: Get rid of the kmalloc_node slab

[Christoph Lameter <cl@linux.com>]

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Currently bootstrap works with the kmalloc_node slab. We can avoid
creating that slab and boot using allocation from a kmalloc array slab
instead. This is necessary for the future if we want to dynamically
size kmem_cache structures.

Signed-off-by: Christoph Lameter <cl@linux-foundation.org>

---
 mm/slub.c |   39 ++++++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 15 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2010-05-20 14:26:53.000000000 -0500
+++ linux-2.6/mm/slub.c	2010-05-20 14:37:19.000000000 -0500
@@ -2111,10 +2111,11 @@ static void early_kmem_cache_node_alloc(
 	struct page *page;
 	struct kmem_cache_node *n;
 	unsigned long flags;
+	int i = kmalloc_index(sizeof(struct kmem_cache_node));
 
-	BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
+	BUG_ON(kmalloc_caches[i].size < sizeof(struct kmem_cache_node));
 
-	page = new_slab(kmalloc_caches, gfpflags, node);
+	page = new_slab(kmalloc_caches + i, gfpflags, node);
 
 	BUG_ON(!page);
 	if (page_to_nid(page) != node) {
@@ -2126,15 +2127,15 @@ static void early_kmem_cache_node_alloc(
 
 	n = page->freelist;
 	BUG_ON(!n);
-	page->freelist = get_freepointer(kmalloc_caches, n);
+	page->freelist = get_freepointer(kmalloc_caches + i, n);
 	page->inuse++;
-	kmalloc_caches->node[node] = n;
+	kmalloc_caches[i].node[node] = n;
 #ifdef CONFIG_SLUB_DEBUG
-	init_object(kmalloc_caches, n, 1);
-	init_tracking(kmalloc_caches, n);
+	init_object(kmalloc_caches + i, n, 1);
+	init_tracking(kmalloc_caches + i, n);
 #endif
-	init_kmem_cache_node(n, kmalloc_caches);
-	inc_slabs_node(kmalloc_caches, node, page->objects);
+	init_kmem_cache_node(n, kmalloc_caches + i);
+	inc_slabs_node(kmalloc_caches + i, node, page->objects);
 
 	/*
 	 * lockdep requires consistent irq usage for each lock
@@ -2152,8 +2153,9 @@ static void free_kmem_cache_nodes(struct
 
 	for_each_node_state(node, N_NORMAL_MEMORY) {
 		struct kmem_cache_node *n = s->node[node];
+
 		if (n && n != &s->local_node)
-			kmem_cache_free(kmalloc_caches, n);
+			kfree(n);
 		s->node[node] = NULL;
 	}
 }
@@ -2178,8 +2180,8 @@ static int init_kmem_cache_nodes(struct 
 				early_kmem_cache_node_alloc(gfpflags, node);
 				continue;
 			}
-			n = kmem_cache_alloc_node(kmalloc_caches,
-							gfpflags, node);
+			n = kmalloc_node(sizeof(struct kmem_cache_node), gfpflags,
+				node);
 
 			if (!n) {
 				free_kmem_cache_nodes(s);
@@ -2574,6 +2576,12 @@ static struct kmem_cache *create_kmalloc
 {
 	unsigned int flags = 0;
 
+	if (s->size) {
+		s->name = name;
+		/* Already created */
+		return s;
+	}
+
 	if (gfp_flags & SLUB_DMA)
 		flags = SLAB_CACHE_DMA;
 
@@ -2978,7 +2986,7 @@ static void slab_mem_offline_callback(vo
 			BUG_ON(slabs_node(s, offline_node));
 
 			s->node[offline_node] = NULL;
-			kmem_cache_free(kmalloc_caches, n);
+			kfree(n);
 		}
 	}
 	up_read(&slub_lock);
@@ -3011,7 +3019,7 @@ static int slab_mem_going_online_callbac
 		 *      since memory is not yet available from the node that
 		 *      is brought up.
 		 */
-		n = kmem_cache_alloc(kmalloc_caches, GFP_KERNEL);
+		n = kmalloc(sizeof(struct kmem_cache_node), GFP_KERNEL);
 		if (!n) {
 			ret = -ENOMEM;
 			goto out;
@@ -3068,9 +3076,10 @@ void __init kmem_cache_init(void)
 	 * struct kmem_cache_node's. There is special bootstrap code in
 	 * kmem_cache_open for slab_state == DOWN.
 	 */
-	create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
+	i = kmalloc_index(sizeof(struct kmem_cache_node));
+	create_kmalloc_cache(&kmalloc_caches[i], "bootstrap",
 		sizeof(struct kmem_cache_node), GFP_NOWAIT);
-	kmalloc_caches[0].refcount = -1;
+	kmalloc_caches[i].refcount = -1;
 	caches++;
 
 	hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);

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