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Commit f1aaee53 authored by Arjan van de Ven's avatar Arjan van de Ven Committed by Linus Torvalds
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[PATCH] lockdep: annotate mm/slab.c 



mm/slab.c uses nested locking when dealing with 'off-slab'
caches, in that case it allocates the slab header from the
(on-slab) kmalloc caches. Teach the lock validator about
this by putting all on-slab caches into a separate class.

this patch has no effect on non-lockdep kernels.

Signed-off-by: default avatarArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 873623df

mm/slab.c

+32 −0
Original line number Diff line number Diff line
@@ -674,6 +674,37 @@ static struct kmem_cache cache_cache = { 
#endif

};



#ifdef CONFIG_LOCKDEP



/*

 * Slab sometimes uses the kmalloc slabs to store the slab headers

 * for other slabs "off slab".

 * 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.

 */

static struct lock_class_key on_slab_key;



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))

			continue;

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

				  &on_slab_key);

	}

}



#else

static inline void init_lock_keys(struct cache_sizes *s)

{

}

#endif







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

static DEFINE_MUTEX(cache_chain_mutex);

static struct list_head cache_chain;
@@ -1391,6 +1422,7 @@ 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,