From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH] slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU Date: Thu, 03 Sep 2009 16:18:47 +0200 Message-ID: <4A9FD047.9000002@gmail.com> References: <4A896324.3040104@trash.net> <4A9EEF07.5070800@gmail.com> <4A9F1620.2080105@gmail.com> <84144f020909022331x2b275aa5n428f88670e0ae8bc@mail.gmail.com> <4A9F7283.1090306@gmail.com> <84144f020909030051u6cf6ae01he25c268f718ff3af@mail.gmail.com> <84144f020909030705x7909cf07w7ea0d3662a66c5cc@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Christoph Lameter , Zdenek Kabelac , Patrick McHardy , Robin Holt , Linux Kernel Mailing List , Jesper Dangaard Brouer , Linux Netdev List , Netfilter Developers , paulmck@linux.vnet.ibm.com, "stable@kernel.org" To: Pekka Enberg Return-path: In-Reply-To: <84144f020909030705x7909cf07w7ea0d3662a66c5cc@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org Pekka Enberg a =E9crit : > Hi Christoph, >=20 > On Thu, 3 Sep 2009, Pekka Enberg wrote: >>> Oh, sure, the fix looks sane to me. It's just that I am a complete >>> coward when it comes to merging RCU related patches so I always try= to >>> fish an Acked-by from Paul or Christoph ;). >=20 > On Thu, Sep 3, 2009 at 8:50 PM, Christoph > Lameter wrote: >> I am fine with acking the poison piece. >=20 > Ok. >=20 > On Thu, Sep 3, 2009 at 8:50 PM, Christoph > Lameter wrote: >> I did not ack the patch that added rcu to kmem_cache_destroy() and I >> likely wont ack that piece either. >=20 > Right. I didn't remember that I merged that over your NAK but I don't > share your view that kmem_cache_destroy() callers should do > rcu_barrier() or whatever is necessary if we can do it from > kmem_cache_destroy(). So I am happy to take both changes but I would > appreciate them being split into two separate patches. >=20 Here is the second patch (RCU thing). Stable candidate [PATCH] slub: Fix kmem_cache_destroy() with SLAB_DESTROY_BY_RCU kmem_cache_destroy() should call rcu_barrier() *after* kmem_cache_close= () and *before* sysfs_slab_remove() or risk rcu_free_slab() being called after kmem_cache is deleted (kfreed). rmmod nf_conntrack can crash the machine because it has to kmem_cache_destroy() a SLAB_DESTROY_BY_RCU enabled cache. Reported-by: Zdenek Kabelac Signed-off-by: Eric Dumazet Acked-by: Paul E. McKenney --- diff --git a/mm/slub.c b/mm/slub.c index b9f1491..b627675 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2594,8 +2594,6 @@ static inline int kmem_cache_close(struct kmem_ca= che *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) { @@ -2606,6 +2604,8 @@ void kmem_cache_destroy(struct kmem_cache *s) "still has objects.\n", s->name, __func__); dump_stack(); } + if (s->flags & SLAB_DESTROY_BY_RCU) + rcu_barrier(); sysfs_slab_remove(s); } else up_write(&slub_lock);