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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: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Arjan van de Ven 2006-07-13 14:46:03 +02:00 committed by Linus Torvalds
parent 873623dfab
commit f1aaee53f2
1 changed files with 32 additions and 0 deletions
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32
mm/slab.c
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@ -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,