From 7ed9f7e5db58c6e8c2b4b738a75d5dcd8e17aad5 Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 25 Jun 2009 12:31:37 -0700 Subject: [PATCH] fix RCU-callback-after-kmem_cache_destroy problem in sl[aou]b 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. Cc: Acked-by: Matt Mackall Reported-by: Jesper Dangaard Brouer Signed-off-by: Paul E. McKenney Signed-off-by: Pekka Enberg --- mm/slab.c | 2 +- mm/slob.c | 2 ++ mm/slub.c | 2 ++ 3 files changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/slab.c b/mm/slab.c index e74a16e4ced..5241b6598ba 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 c78742defdc..9641da3d5e5 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 819f056b39c..a9201d83178 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) {