Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757510AbZFZJEF (ORCPT ); Fri, 26 Jun 2009 05:04:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754926AbZFZJDz (ORCPT ); Fri, 26 Jun 2009 05:03:55 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38950 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754963AbZFZJDz (ORCPT ); Fri, 26 Jun 2009 05:03:55 -0400 Date: Fri, 26 Jun 2009 11:03:55 +0200 From: Nick Piggin To: Matt Mackall Cc: paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, cl@linux-foundation.org, penberg@cs.helsinki.fi, jdb@comx.dk Subject: Re: [PATCH RFC] fix RCU-callback-after-kmem_cache_destroy problem in sl[aou]b Message-ID: <20090626090355.GA11450@wotan.suse.de> References: <20090625193137.GA16861@linux.vnet.ibm.com> <1245965239.21085.393.camel@calx> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1245965239.21085.393.camel@calx> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2422 Lines: 75 On Thu, Jun 25, 2009 at 04:27:19PM -0500, Matt Mackall wrote: > On Thu, 2009-06-25 at 12:31 -0700, Paul E. McKenney wrote: > > 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. > > Acked-by: Matt Mackall > > Nick, you'll want to make sure you get this in SLQB. Thanks Matt. Paul, I think this should be appropriate for stable@kernel.org too? > > > Reported-by: Jesper Dangaard Brouer > > Signed-off-by: Paul E. McKenney > > --- > > > > 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) { > > -- > http://selenic.com : development and support for Mercurial and Linux > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/