Commit 2b2d5493 authored by Ingo Molnar's avatar Ingo Molnar Committed by Linus Torvalds
Browse files

[PATCH] lockdep: annotate SLAB code 



Teach special (recursive) locking code to the lock validator.  Has no effect
on non-lockdep kernels.

Fix initialize-locks-via-memcpy assumptions.

Effects on non-lockdep kernels: the subclass nesting parameter is passed into
cache_free_alien() and __cache_free(), and turns one internal
kmem_cache_free() call into an open-coded __cache_free() call.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 897c6ff9

mm/slab.c

+48 −11
Original line number Diff line number Diff line
@@ -1021,7 +1021,8 @@ static void drain_alien_cache(struct kmem_cache *cachep, 
	}

}



static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)

static inline int cache_free_alien(struct kmem_cache *cachep, void *objp,

				   int nesting)

{

	struct slab *slabp = virt_to_slab(objp);

	int nodeid = slabp->nodeid;
@@ -1039,7 +1040,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp) 
	STATS_INC_NODEFREES(cachep);

	if (l3->alien && l3->alien[nodeid]) {

		alien = l3->alien[nodeid];

		spin_lock(&alien->lock);

		spin_lock_nested(&alien->lock, nesting);

		if (unlikely(alien->avail == alien->limit)) {

			STATS_INC_ACOVERFLOW(cachep);

			__drain_alien_cache(cachep, alien, nodeid);
@@ -1068,7 +1069,8 @@ static inline void free_alien_cache(struct array_cache **ac_ptr) 
{

}



static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)

static inline int cache_free_alien(struct kmem_cache *cachep, void *objp,

				   int nesting)

{

	return 0;

}
@@ -1272,6 +1274,11 @@ static void init_list(struct kmem_cache *cachep, struct kmem_list3 *list, 


	local_irq_disable();

	memcpy(ptr, list, sizeof(struct kmem_list3));

	/*

	 * Do not assume that spinlocks can be initialized via memcpy:

	 */

	spin_lock_init(&ptr->list_lock);



	MAKE_ALL_LISTS(cachep, ptr, nodeid);

	cachep->nodelists[nodeid] = ptr;

	local_irq_enable();
@@ -1398,7 +1405,7 @@ void __init kmem_cache_init(void) 
	}

	/* 4) Replace the bootstrap head arrays */

	{

		void *ptr;

		struct array_cache *ptr;



		ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL);
@@ -1406,6 +1413,11 @@ void __init kmem_cache_init(void) 
		BUG_ON(cpu_cache_get(&cache_cache) != &initarray_cache.cache);

		memcpy(ptr, cpu_cache_get(&cache_cache),

		       sizeof(struct arraycache_init));

		/*

		 * Do not assume that spinlocks can be initialized via memcpy:

		 */

		spin_lock_init(&ptr->lock);



		cache_cache.array[smp_processor_id()] = ptr;

		local_irq_enable();
@@ -1416,6 +1428,11 @@ void __init kmem_cache_init(void) 
		       != &initarray_generic.cache);

		memcpy(ptr, cpu_cache_get(malloc_sizes[INDEX_AC].cs_cachep),

		       sizeof(struct arraycache_init));

		/*

		 * Do not assume that spinlocks can be initialized via memcpy:

		 */

		spin_lock_init(&ptr->lock);



		malloc_sizes[INDEX_AC].cs_cachep->array[smp_processor_id()] =

		    ptr;

		local_irq_enable();
@@ -1743,6 +1760,8 @@ static void slab_destroy_objs(struct kmem_cache *cachep, struct slab *slabp) 
}

#endif



static void __cache_free(struct kmem_cache *cachep, void *objp, int nesting);



/**

 * slab_destroy - destroy and release all objects in a slab

 * @cachep: cache pointer being destroyed
@@ -1766,8 +1785,17 @@ static void slab_destroy(struct kmem_cache *cachep, struct slab *slabp) 
		call_rcu(&slab_rcu->head, kmem_rcu_free);

	} else {

		kmem_freepages(cachep, addr);

		if (OFF_SLAB(cachep))

			kmem_cache_free(cachep->slabp_cache, slabp);

		if (OFF_SLAB(cachep)) {

			unsigned long flags;



			/*

		 	 * lockdep: we may nest inside an already held

			 * ac->lock, so pass in a nesting flag:

			 */

			local_irq_save(flags);

			__cache_free(cachep->slabp_cache, slabp, 1);

			local_irq_restore(flags);

		}

	}

}
@@ -3072,7 +3100,16 @@ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects, 
		if (slabp->inuse == 0) {

			if (l3->free_objects > l3->free_limit) {

				l3->free_objects -= cachep->num;

				/*

				 * It is safe to drop the lock. The slab is

				 * no longer linked to the cache. cachep

				 * cannot disappear - we are using it and

				 * all destruction of caches must be

				 * serialized properly by the user.

				 */

				spin_unlock(&l3->list_lock);

				slab_destroy(cachep, slabp);

				spin_lock(&l3->list_lock);

			} else {

				list_add(&slabp->list, &l3->slabs_free);

			}
@@ -3098,7 +3135,7 @@ static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac) 
#endif

	check_irq_off();

	l3 = cachep->nodelists[node];

	spin_lock(&l3->list_lock);

	spin_lock_nested(&l3->list_lock, SINGLE_DEPTH_NESTING);

	if (l3->shared) {

		struct array_cache *shared_array = l3->shared;

		int max = shared_array->limit - shared_array->avail;
@@ -3141,14 +3178,14 @@ free_done: 
 * Release an obj back to its cache. If the obj has a constructed state, it must

 * be in this state _before_ it is released.  Called with disabled ints.

 */

static inline void __cache_free(struct kmem_cache *cachep, void *objp)

static void __cache_free(struct kmem_cache *cachep, void *objp, int nesting)

{

	struct array_cache *ac = cpu_cache_get(cachep);



	check_irq_off();

	objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0));



	if (cache_free_alien(cachep, objp))

	if (cache_free_alien(cachep, objp, nesting))

		return;



	if (likely(ac->avail < ac->limit)) {
@@ -3387,7 +3424,7 @@ void kmem_cache_free(struct kmem_cache *cachep, void *objp) 
	BUG_ON(virt_to_cache(objp) != cachep);



	local_irq_save(flags);

	__cache_free(cachep, objp);

	__cache_free(cachep, objp, 0);

	local_irq_restore(flags);

}

EXPORT_SYMBOL(kmem_cache_free);
@@ -3412,7 +3449,7 @@ void kfree(const void *objp) 
	kfree_debugcheck(objp);

	c = virt_to_cache(objp);

	debug_check_no_locks_freed(objp, obj_size(c));

	__cache_free(c, (void *)objp);

	__cache_free(c, (void *)objp, 0);

	local_irq_restore(flags);

}

EXPORT_SYMBOL(kfree);

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