On Fri, 21 May 2010, Christoph Lameter wrote:
> Currently bootstrap works with the kmalloc_node slab.
s/kmalloc_node/kmem_cache_node/
> 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@xxxxxxxxxxxxxxxxxxxx>
>
> ---
> 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));
>
const int?
Maybe even better would be
struct kmem_cache *s = kmalloc_caches + i;
to make the rest of this easier?
> - 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);
I don't think we need this BUG_ON() anymore, but that's a seperate issue.
> - 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;
Do we need this? The iteration at the end of kmem_cache_init() should
reset this kmalloc cache to have the standard kmalloc-<size> name, so I
don't think we need to reset "bootstrap" here.
> + /* 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);
So kmalloc_caches[0] will never be used after this change, then?
We could also remove the gfp_t argument to create_kmalloc_cache(), it's
not used for anything other than GFP_NOWAIT anymore.
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