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Commit 51df1142 authored by Christoph Lameter's avatar Christoph Lameter Committed by Pekka Enberg
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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: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: default avatarPekka Enberg <penberg@kernel.org>
parent 6c182dc0

include/linux/slub_def.h

+2 −5
Original line number Diff line number Diff line
@@ -139,19 +139,16 @@ struct kmem_cache { 


#ifdef CONFIG_ZONE_DMA

#define SLUB_DMA __GFP_DMA

/* Reserve extra caches for potential DMA use */

#define KMALLOC_CACHES (2 * SLUB_PAGE_SHIFT)

#else

/* Disable DMA functionality */

#define SLUB_DMA (__force gfp_t)0

#define KMALLOC_CACHES SLUB_PAGE_SHIFT

#endif



/*

 * We keep the general caches in an array of slab caches that are used for

 * 2^x bytes of allocations.

 */

extern struct kmem_cache kmalloc_caches[KMALLOC_CACHES];

extern struct kmem_cache *kmalloc_caches[SLUB_PAGE_SHIFT];



/*

 * Sorry that the following has to be that ugly but some versions of GCC
@@ -216,7 +213,7 @@ static __always_inline struct kmem_cache *kmalloc_slab(size_t size) 
	if (index == 0)

		return NULL;



	return &kmalloc_caches[index];

	return kmalloc_caches[index];

}



void *kmem_cache_alloc(struct kmem_cache *, gfp_t);

mm/slub.c

+138 −53
Original line number Diff line number Diff line
@@ -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);



#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);



	for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {

		create_kmalloc_cache(&kmalloc_caches[i],

			"kmalloc", 1 << i, 0);

	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