slub: Dynamically size kmalloc cache allocations

kmalloc caches are statically defined and may take up a lot of space just
because the sizes of the node array has to be dimensioned for the largest
node count supported.

This patch makes the size of the kmem_cache structure dynamic throughout by
creating a kmem_cache slab cache for the kmem_cache objects. The bootstrap
occurs by allocating the initial one or two kmem_cache objects from the
page allocator.

C2->C3
	- Fix various issues indicated by David
	- Make create kmalloc_cache return a kmem_cache * pointer.

Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

1 files changed, 138 insertions, 53 deletions

diff --git a/mm/slub.c b/mm/slub.c
index e8c117595367..94fee96da0d2 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -168,7 +168,6 @@ static inline int kmem_cache_debug(struct kmem_cache *s)
 
 /* Internal SLUB flags */
 #define __OBJECT_POISON         0x80000000UL /* Poison object */
-#define __SYSFS_ADD_DEFERRED    0x40000000UL /* Not yet visible via sysfs */
 
 static int kmem_size = sizeof(struct kmem_cache);
 
@@ -178,7 +177,7 @@ static struct notifier_block slab_notifier;
 
 static enum {
         DOWN,           /* No slab functionality available */
-        PARTIAL,        /* kmem_cache_open() works but kmalloc does not */
+        PARTIAL,        /* Kmem_cache_node works */
         UP,             /* Everything works but does not show up in sysfs */
         SYSFS           /* Sysfs up */
 } slab_state = DOWN;
@@ -2073,6 +2072,8 @@ static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
 }
 
 #ifdef CONFIG_NUMA
+static struct kmem_cache *kmem_cache_node;
+
 /*
  * No kmalloc_node yet so do it by hand. We know that this is the first
  * slab on the node for this slabcache. There are no concurrent accesses
@@ -2088,9 +2089,9 @@ static void early_kmem_cache_node_alloc(int node)
         struct kmem_cache_node *n;
         unsigned long flags;
 
-        BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
+        BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
 
-        page = new_slab(kmalloc_caches, GFP_NOWAIT, node);
+        page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
 
         BUG_ON(!page);
         if (page_to_nid(page) != node) {
@@ -2102,15 +2103,15 @@ static void early_kmem_cache_node_alloc(int node)
 
         n = page->freelist;
         BUG_ON(!n);
-        page->freelist = get_freepointer(kmalloc_caches, n);
+        page->freelist = get_freepointer(kmem_cache_node, n);
         page->inuse++;
-        kmalloc_caches->node[node] = n;
+        kmem_cache_node->node[node] = n;
 #ifdef CONFIG_SLUB_DEBUG
-        init_object(kmalloc_caches, n, 1);
-        init_tracking(kmalloc_caches, n);
+        init_object(kmem_cache_node, n, 1);
+        init_tracking(kmem_cache_node, n);
 #endif
-        init_kmem_cache_node(n, kmalloc_caches);
-        inc_slabs_node(kmalloc_caches, node, page->objects);
+        init_kmem_cache_node(n, kmem_cache_node);
+        inc_slabs_node(kmem_cache_node, node, page->objects);
 
         /*
          * lockdep requires consistent irq usage for each lock
@@ -2128,8 +2129,10 @@ static void free_kmem_cache_nodes(struct kmem_cache *s)
 
         for_each_node_state(node, N_NORMAL_MEMORY) {
                 struct kmem_cache_node *n = s->node[node];
+
                 if (n)
-                        kmem_cache_free(kmalloc_caches, n);
+                        kmem_cache_free(kmem_cache_node, n);
+
                 s->node[node] = NULL;
         }
 }
@@ -2145,7 +2148,7 @@ static int init_kmem_cache_nodes(struct kmem_cache *s)
                         early_kmem_cache_node_alloc(node);
                         continue;
                 }
-                n = kmem_cache_alloc_node(kmalloc_caches,
+                n = kmem_cache_alloc_node(kmem_cache_node,
                                                 GFP_KERNEL, node);
 
                 if (!n) {
@@ -2498,11 +2501,13 @@ EXPORT_SYMBOL(kmem_cache_destroy);
  *              Kmalloc subsystem
  *******************************************************************/
 
-struct kmem_cache kmalloc_caches[KMALLOC_CACHES] __cacheline_aligned;
+struct kmem_cache *kmalloc_caches[SLUB_PAGE_SHIFT];
 EXPORT_SYMBOL(kmalloc_caches);
 
+static struct kmem_cache *kmem_cache;
+
 #ifdef CONFIG_ZONE_DMA
-static struct kmem_cache kmalloc_dma_caches[SLUB_PAGE_SHIFT];
+static struct kmem_cache *kmalloc_dma_caches[SLUB_PAGE_SHIFT];
 #endif
 
 static int __init setup_slub_min_order(char *str)
@@ -2541,9 +2546,13 @@ static int __init setup_slub_nomerge(char *str)
 
 __setup("slub_nomerge", setup_slub_nomerge);
 
-static void create_kmalloc_cache(struct kmem_cache *s,
-                const char *name, int size, unsigned int flags)
+static struct kmem_cache *__init create_kmalloc_cache(const char *name,
+                                                int size, unsigned int flags)
 {
+        struct kmem_cache *s;
+
+        s = kmem_cache_alloc(kmem_cache, GFP_NOWAIT);
+
         /*
          * This function is called with IRQs disabled during early-boot on
          * single CPU so there's no need to take slub_lock here.
@@ -2553,12 +2562,11 @@ static void create_kmalloc_cache(struct kmem_cache *s,
                 goto panic;
 
         list_add(&s->list, &slab_caches);
-
-        if (!sysfs_slab_add(s))
-                return;
+        return s;
 
 panic:
         panic("Creation of kmalloc slab %s size=%d failed.\n", name, size);
+        return NULL;
 }
 
 /*
@@ -2613,10 +2621,10 @@ static struct kmem_cache *get_slab(size_t size, gfp_t flags)
 
 #ifdef CONFIG_ZONE_DMA
         if (unlikely((flags & SLUB_DMA)))
-                return &kmalloc_dma_caches[index];
+                return kmalloc_dma_caches[index];
 
 #endif
-        return &kmalloc_caches[index];
+        return kmalloc_caches[index];
 }
 
 void *__kmalloc(size_t size, gfp_t flags)
@@ -2940,46 +2948,113 @@ static int slab_memory_callback(struct notifier_block *self,
  *                      Basic setup of slabs
  *******************************************************************/
 
+/*
+ * Used for early kmem_cache structures that were allocated using
+ * the page allocator
+ */
+
+static void __init kmem_cache_bootstrap_fixup(struct kmem_cache *s)
+{
+        int node;
+
+        list_add(&s->list, &slab_caches);
+        s->refcount = -1;
+
+        for_each_node_state(node, N_NORMAL_MEMORY) {
+                struct kmem_cache_node *n = get_node(s, node);
+                struct page *p;
+
+                if (n) {
+                        list_for_each_entry(p, &n->partial, lru)
+                                p->slab = s;
+
+#ifdef CONFIG_SLAB_DEBUG
+                        list_for_each_entry(p, &n->full, lru)
+                                p->slab = s;
+#endif
+                }
+        }
+}
+
 void __init kmem_cache_init(void)
 {
         int i;
         int caches = 0;
+        struct kmem_cache *temp_kmem_cache;
+        int order;
 
 #ifdef CONFIG_NUMA
+        struct kmem_cache *temp_kmem_cache_node;
+        unsigned long kmalloc_size;
+
+        kmem_size = offsetof(struct kmem_cache, node) +
+                                nr_node_ids * sizeof(struct kmem_cache_node *);
+
+        /* Allocate two kmem_caches from the page allocator */
+        kmalloc_size = ALIGN(kmem_size, cache_line_size());
+        order = get_order(2 * kmalloc_size);
+        kmem_cache = (void *)__get_free_pages(GFP_NOWAIT, order);
+
         /*
          * Must first have the slab cache available for the allocations of the
          * 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",
-                sizeof(struct kmem_cache_node), 0);
-        kmalloc_caches[0].refcount = -1;
-        caches++;
+        kmem_cache_node = (void *)kmem_cache + kmalloc_size;
+
+        kmem_cache_open(kmem_cache_node, "kmem_cache_node",
+                sizeof(struct kmem_cache_node),
+                0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
 
         hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
+#else
+        /* Allocate a single kmem_cache from the page allocator */
+        kmem_size = sizeof(struct kmem_cache);
+        order = get_order(kmem_size);
+        kmem_cache = (void *)__get_free_pages(GFP_NOWAIT, order);
 #endif
 
         /* Able to allocate the per node structures */
         slab_state = PARTIAL;
 
-        /* Caches that are not of the two-to-the-power-of size */
-        if (KMALLOC_MIN_SIZE <= 32) {
-                create_kmalloc_cache(&kmalloc_caches[1],
-                                "kmalloc-96", 96, 0);
-                caches++;
-        }
-        if (KMALLOC_MIN_SIZE <= 64) {
-                create_kmalloc_cache(&kmalloc_caches[2],
-                                "kmalloc-192", 192, 0);
-                caches++;
-        }
+        temp_kmem_cache = kmem_cache;
+        kmem_cache_open(kmem_cache, "kmem_cache", kmem_size,
+                0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, NULL);
+        kmem_cache = kmem_cache_alloc(kmem_cache, GFP_NOWAIT);
+        memcpy(kmem_cache, temp_kmem_cache, kmem_size);
 
-        for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
-                create_kmalloc_cache(&kmalloc_caches[i],
-                        "kmalloc", 1 << i, 0);
-                caches++;
-        }
+#ifdef CONFIG_NUMA
+        /*
+         * Allocate kmem_cache_node properly from the kmem_cache slab.
+         * kmem_cache_node is separately allocated so no need to
+         * update any list pointers.
+         */
+        temp_kmem_cache_node = kmem_cache_node;
 
+        kmem_cache_node = kmem_cache_alloc(kmem_cache, GFP_NOWAIT);
+        memcpy(kmem_cache_node, temp_kmem_cache_node, kmem_size);
+
+        kmem_cache_bootstrap_fixup(kmem_cache_node);
+
+        caches++;
+#else
+        /*
+         * kmem_cache has kmem_cache_node embedded and we moved it!
+         * Update the list heads
+         */
+        INIT_LIST_HEAD(&kmem_cache->local_node.partial);
+        list_splice(&temp_kmem_cache->local_node.partial, &kmem_cache->local_node.partial);
+#ifdef CONFIG_SLUB_DEBUG
+        INIT_LIST_HEAD(&kmem_cache->local_node.full);
+        list_splice(&temp_kmem_cache->local_node.full, &kmem_cache->local_node.full);
+#endif
+#endif
+        kmem_cache_bootstrap_fixup(kmem_cache);
+        caches++;
+        /* Free temporary boot structure */
+        free_pages((unsigned long)temp_kmem_cache, order);
+
+        /* Now we can use the kmem_cache to allocate kmalloc slabs */
 
         /*
          * Patch up the size_index table if we have strange large alignment
@@ -3019,6 +3094,22 @@ void __init kmem_cache_init(void)
                         size_index[size_index_elem(i)] = 8;
         }
 
+        /* Caches that are not of the two-to-the-power-of size */
+        if (KMALLOC_MIN_SIZE <= 32) {
+                kmalloc_caches[1] = create_kmalloc_cache("kmalloc-96", 96, 0);
+                caches++;
+        }
+
+        if (KMALLOC_MIN_SIZE <= 64) {
+                kmalloc_caches[2] = create_kmalloc_cache("kmalloc-192", 192, 0);
+                caches++;
+        }
+
+        for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
+                kmalloc_caches[i] = create_kmalloc_cache("kmalloc", 1 << i, 0);
+                caches++;
+        }
+
         slab_state = UP;
 
         /* Provide the correct kmalloc names now that the caches are up */
@@ -3026,30 +3117,24 @@ void __init kmem_cache_init(void)
                 char *s = kasprintf(GFP_NOWAIT, "kmalloc-%d", 1 << i);
 
                 BUG_ON(!s);
-                kmalloc_caches[i].name = s;
+                kmalloc_caches[i]->name = s;
         }
 
 #ifdef CONFIG_SMP
         register_cpu_notifier(&slab_notifier);
 #endif
-#ifdef CONFIG_NUMA
-        kmem_size = offsetof(struct kmem_cache, node) +
-                                nr_node_ids * sizeof(struct kmem_cache_node *);
-#else
-        kmem_size = sizeof(struct kmem_cache);
-#endif
 
 #ifdef CONFIG_ZONE_DMA
-        for (i = 1; i < SLUB_PAGE_SHIFT; i++) {
-                struct kmem_cache *s = &kmalloc_caches[i];
+        for (i = 0; i < SLUB_PAGE_SHIFT; i++) {
+                struct kmem_cache *s = kmalloc_caches[i];
 
-                if (s->size) {
+                if (s && s->size) {
                         char *name = kasprintf(GFP_NOWAIT,
                                  "dma-kmalloc-%d", s->objsize);
 
                         BUG_ON(!name);
-                        create_kmalloc_cache(&kmalloc_dma_caches[i],
-                                name, s->objsize, SLAB_CACHE_DMA);
+                        kmalloc_dma_caches[i] = create_kmalloc_cache(name,
+                                s->objsize, SLAB_CACHE_DMA);
                 }
         }
 #endif