Messages in this thread Patch in this message | | | Date | Thu, 25 Jun 2009 12:31:37 -0700 | From | "Paul E. McKenney" <> | Subject | [PATCH RFC] fix RCU-callback-after-kmem_cache_destroy problem in sl[aou]b |
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Hello!
Jesper noted that kmem_cache_destroy() invokes synchronize_rcu() rather than rcu_barrier() in the SLAB_DESTROY_BY_RCU case, which could result in RCU callbacks accessing a kmem_cache after it had been destroyed.
The following untested (might not even compile) patch proposes a fix.
Reported-by: Jesper Dangaard Brouer <jdb@comx.dk> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> ---
slab.c | 2 +- slob.c | 2 ++ slub.c | 2 ++ 3 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/slab.c b/mm/slab.c index e74a16e..5241b65 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -2547,7 +2547,7 @@ void kmem_cache_destroy(struct kmem_cache *cachep) } if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) - synchronize_rcu(); + rcu_barrier(); __kmem_cache_destroy(cachep); mutex_unlock(&cache_chain_mutex); diff --git a/mm/slob.c b/mm/slob.c index c78742d..9641da3 100644 --- a/mm/slob.c +++ b/mm/slob.c @@ -595,6 +595,8 @@ EXPORT_SYMBOL(kmem_cache_create); void kmem_cache_destroy(struct kmem_cache *c) { kmemleak_free(c); + if (c->flags & SLAB_DESTROY_BY_RCU) + rcu_barrier(); slob_free(c, sizeof(struct kmem_cache)); } EXPORT_SYMBOL(kmem_cache_destroy); diff --git a/mm/slub.c b/mm/slub.c index 819f056..a9201d8 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2595,6 +2595,8 @@ static inline int kmem_cache_close(struct kmem_cache *s) */ void kmem_cache_destroy(struct kmem_cache *s) { + if (s->flags & SLAB_DESTROY_BY_RCU) + rcu_barrier(); down_write(&slub_lock); s->refcount--; if (!s->refcount) {
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