On 09/27/2012 12:20 AM, Christoph Lameter wrote:
> Simplify bootstrap by statically allocated two kmem_cache structures. These are
> freed after bootup is complete. Allows us to no longer worry about calculations
> of sizes of kmem_cache structures during bootstrap.
>
> V1->V2: Do not unlock mutexes that are not taken during early boot.
>
This V1->V2 change makes sense, btw.
> Reviewed-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
> ---
> mm/slub.c | 41 +++++++++++------------------------------
> 1 file changed, 11 insertions(+), 30 deletions(-)
>
> Index: linux/mm/slub.c
> ===================================================================
> --- linux.orig/mm/slub.c 2012-09-19 09:21:14.422971030 -0500
> +++ linux/mm/slub.c 2012-09-19 09:21:18.403053765 -0500
> @@ -3649,9 +3649,6 @@ static void __init kmem_cache_bootstrap_
> {
> 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;
> @@ -3668,14 +3665,13 @@ static void __init kmem_cache_bootstrap_
> }
> }
>
> +static __initdata struct kmem_cache boot_kmem_cache,
> + boot_kmem_cache_node;
> +
> void __init kmem_cache_init(void)
> {
> int i;
> - int caches = 0;
> - struct kmem_cache *temp_kmem_cache;
> - int order;
> - struct kmem_cache *temp_kmem_cache_node;
> - unsigned long kmalloc_size;
> + int caches = 2;
>
> if (debug_guardpage_minorder())
> slub_max_order = 0;
> @@ -3683,53 +3679,32 @@ void __init kmem_cache_init(void)
> 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 | __GFP_ZERO, 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.
> - */
> - kmem_cache_node = (void *)kmem_cache + kmalloc_size;
> + kmem_cache_node = &boot_kmem_cache_node;
>
> - kmem_cache_node->name = "kmem_cache_node";
> - kmem_cache_node->size = kmem_cache_node->object_size =
> - sizeof(struct kmem_cache_node);
> - kmem_cache_open(kmem_cache_node, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
> + create_boot_cache(kmem_cache_node, "kmem_cache_node",
> + sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN);
>
> hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
>
> /* Able to allocate the per node structures */
> slab_state = PARTIAL;
>
> - temp_kmem_cache = kmem_cache;
> - kmem_cache->name = "kmem_cache";
> - kmem_cache->size = kmem_cache->object_size = kmem_size;
> - kmem_cache_open(kmem_cache, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
> + create_boot_cache(&boot_kmem_cache, "kmem_cache", kmem_size,
> + SLAB_HWCACHE_ALIGN);
>
> - kmem_cache = kmem_cache_alloc(kmem_cache, GFP_NOWAIT);
> - memcpy(kmem_cache, temp_kmem_cache, kmem_size);
> + kmem_cache = kmem_cache_alloc(&boot_kmem_cache, GFP_NOWAIT);
> + memcpy(kmem_cache, &boot_kmem_cache, kmem_size);
>
> /*
> * 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);
> + memcpy(kmem_cache_node, &boot_kmem_cache_node, kmem_size);
>
> kmem_cache_bootstrap_fixup(kmem_cache_node);
> -
> - caches++;
> 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 */
>
> @@ -3930,6 +3905,10 @@ int __kmem_cache_create(struct kmem_cach
> if (err)
> return err;
>
> + /* Mutex is not taken during early boot */
> + if (slab_state <= UP)
> + return 0;
> +
> mutex_unlock(&slab_mutex);
> err = sysfs_slab_add(s);
> mutex_lock(&slab_mutex);
>
> --
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