Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754638AbdGJUck (ORCPT ); Mon, 10 Jul 2017 16:32:40 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:54802 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752158AbdGJUcj (ORCPT ); Mon, 10 Jul 2017 16:32:39 -0400 Date: Mon, 10 Jul 2017 13:32:38 -0700 From: Andrew Morton To: Christoph Lameter Cc: Alexander Potapenko , dvyukov@google.com, kcc@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Pekka Enberg , David Rientjes , Joonsoo Kim Subject: Re: [PATCH] slub: make sure struct kmem_cache_node is initialized before publication Message-Id: <20170710133238.2afcda57ea28e020ca03c4f0@linux-foundation.org> In-Reply-To: References: <20170707083408.40410-1-glider@google.com> <20170707132351.4f10cd778fc5eb58e9cc5513@linux-foundation.org> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1073 Lines: 37 On Fri, 7 Jul 2017 18:18:31 -0500 (CDT) Christoph Lameter wrote: > On Fri, 7 Jul 2017, Andrew Morton wrote: > > > On Fri, 7 Jul 2017 10:34:08 +0200 Alexander Potapenko wrote: > > > > > --- a/mm/slub.c > > > +++ b/mm/slub.c > > > @@ -3389,8 +3389,8 @@ static int init_kmem_cache_nodes(struct kmem_cache *s) > > > return 0; > > > } > > > > > > - s->node[node] = n; > > > init_kmem_cache_node(n); > > > + s->node[node] = n; > > > } > > > return 1; > > > } > > > > If this matters then I have bad feelings about free_kmem_cache_nodes(): > > At creation time the kmem_cache structure is private and no one can run a > free operation. > > > Inviting a use-after-free? I guess not, as there should be no way > > to look up these items at this stage. > > Right. Still. It looks bad, and other sites do these things in the other order. > > Could the slab maintainers please take a look at these and also have a > > think about Alexander's READ_ONCE/WRITE_ONCE question? > > Was I cced on these? It's all on linux-mm.