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Date: Mon, 10 Jul 2017 13:32:38 -0700
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] slub: make sure struct kmem_cache_node is initialized
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To: Christoph Lameter <cl@linux.com>
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>

On Fri, 7 Jul 2017 18:18:31 -0500 (CDT) Christoph Lameter <cl@linux.com> wrote:

> 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.

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.

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