Date: Fri, 7 Jul 2017 18:18:31 -0500 (CDT)
From: Christoph Lameter <cl@linux.com>
To: Andrew Morton <akpm@linux-foundation.org>
cc: Alexander Potapenko <glider@google.com>, dvyukov@google.com,
        kcc@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH] slub: make sure struct kmem_cache_node is initialized
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References: <20170707083408.40410-1-glider@google.com> <20170707132351.4f10cd778fc5eb58e9cc5513@linux-foundation.org>
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On Fri, 7 Jul 2017, Andrew Morton wrote:

> On Fri,  7 Jul 2017 10:34:08 +0200 Alexander Potapenko <glider@google.com> 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.

> 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?