Commit 056c6241 authored by Ravikiran G Thirumalai's avatar Ravikiran G Thirumalai Committed by Linus Torvalds
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[PATCH] slab: fix lockdep warnings 



Place the alien array cache locks of on slab malloc slab caches on a
seperate lockdep class.  This avoids false positives from lockdep

[akpm@osdl.org: build fix]
Signed-off-by: default avatarRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: default avatarShai Fultheim <shai@scalex86.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 2ed3a4ef

mm/slab.c

+43 −14
Original line number Diff line number Diff line
@@ -674,6 +674,8 @@ static struct kmem_cache cache_cache = { 
#endif

};



#define BAD_ALIEN_MAGIC 0x01020304ul



#ifdef CONFIG_LOCKDEP



/*
@@ -682,29 +684,53 @@ static struct kmem_cache cache_cache = { 
 * The locking for this is tricky in that it nests within the locks

 * of all other slabs in a few places; to deal with this special

 * locking we put on-slab caches into a separate lock-class.

 *

 * We set lock class for alien array caches which are up during init.

 * The lock annotation will be lost if all cpus of a node goes down and

 * then comes back up during hotplug

 */

static struct lock_class_key on_slab_key;

static struct lock_class_key on_slab_l3_key;

static struct lock_class_key on_slab_alc_key;



static inline void init_lock_keys(void)



static inline void init_lock_keys(struct cache_sizes *s)

{

	int q;



	for (q = 0; q < MAX_NUMNODES; q++) {

		if (!s->cs_cachep->nodelists[q] || OFF_SLAB(s->cs_cachep))

	struct cache_sizes *s = malloc_sizes;



	while (s->cs_size != ULONG_MAX) {

		for_each_node(q) {

			struct array_cache **alc;

			int r;

			struct kmem_list3 *l3 = s->cs_cachep->nodelists[q];

			if (!l3 || OFF_SLAB(s->cs_cachep))

				continue;

			lockdep_set_class(&l3->list_lock, &on_slab_l3_key);

			alc = l3->alien;

			/*

			 * FIXME: This check for BAD_ALIEN_MAGIC

			 * should go away when common slab code is taught to

			 * work even without alien caches.

			 * Currently, non NUMA code returns BAD_ALIEN_MAGIC

			 * for alloc_alien_cache,

			 */

			if (!alc || (unsigned long)alc == BAD_ALIEN_MAGIC)

				continue;

		lockdep_set_class(&s->cs_cachep->nodelists[q]->list_lock,

				  &on_slab_key);

			for_each_node(r) {

				if (alc[r])

					lockdep_set_class(&alc[r]->lock,

					     &on_slab_alc_key);

			}

		}

		s++;

	}

}



#else

static inline void init_lock_keys(struct cache_sizes *s)

static inline void init_lock_keys(void)

{

}

#endif







/* Guard access to the cache-chain. */

static DEFINE_MUTEX(cache_chain_mutex);

static struct list_head cache_chain;
@@ -1091,7 +1117,7 @@ static inline int cache_free_alien(struct kmem_cache *cachep, void *objp) 


static inline struct array_cache **alloc_alien_cache(int node, int limit)

{

	return (struct array_cache **) 0x01020304ul;

	return (struct array_cache **)BAD_ALIEN_MAGIC;

}



static inline void free_alien_cache(struct array_cache **ac_ptr)
@@ -1421,7 +1447,6 @@ void __init kmem_cache_init(void) 
					ARCH_KMALLOC_FLAGS|SLAB_PANIC,

					NULL, NULL);

		}

		init_lock_keys(sizes);



		sizes->cs_dmacachep = kmem_cache_create(names->name_dma,

					sizes->cs_size,
@@ -1495,6 +1520,10 @@ void __init kmem_cache_init(void) 
		mutex_unlock(&cache_chain_mutex);

	}



	/* Annotate slab for lockdep -- annotate the malloc caches */

	init_lock_keys();





	/* Done! */

	g_cpucache_up = FULL;