From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 3E9E06B004F for ; Thu, 25 Jun 2009 18:08:28 -0400 (EDT) Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e9.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id n5PLuJoL031907 for ; Thu, 25 Jun 2009 17:56:19 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n5PM8bhH155158 for ; Thu, 25 Jun 2009 18:08:41 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n5PM8a84008673 for ; Thu, 25 Jun 2009 18:08:37 -0400 Date: Thu, 25 Jun 2009 15:08:37 -0700 From: "Paul E. McKenney" Subject: Re: [PATCH RFC] fix RCU-callback-after-kmem_cache_destroy problem in sl[aou]b Message-ID: <20090625220837.GD8852@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com 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> Sender: owner-linux-mm@kvack.org To: Matt Mackall Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, cl@linux-foundation.org, penberg@cs.helsinki.fi, jdb@comx.dk, Nick Piggin List-ID: 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. > > > Reported-by: Jesper Dangaard Brouer And I seem to have blown Jesper's email address (apologies, Jesper!), so: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org