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Date: Mon, 3 Apr 2017 07:53:20 -0700
From: Matthew Wilcox <willy@infradead.org>
To: Christoph Lameter <cl@linux.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>,
        Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Joonsoo Kim <iamjoonsoo.kim@lge.com>, Linux-MM <linux-mm@kvack.org>,
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Subject: Re: [PATCH] mm: Add additional consistency check
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On Mon, Apr 03, 2017 at 09:03:50AM -0500, Christoph Lameter wrote:
> On Mon, 3 Apr 2017, Michael Ellerman wrote:
> 
> > At least in slab.c it seems that would allow you to "free" an object
> > from one kmem_cache onto the array_cache of another kmem_cache, which
> > seems fishy. But maybe there's a check somewhere I'm missing?
> 
> kfree can be used to free any object from any slab cache.

Is that a guarantee?  There's some wording in the RCU free code that
seems to indicate we can't rely on that being true.