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Date:   Fri, 9 Aug 2019 07:26:17 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Miles Chen <miles.chen@mediatek.com>
Cc:     Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org,
        wsd_upstream@mediatek.com, "Tobin C . Harding" <me@tobin.cc>,
        Kees Cook <keescook@chromium.org>
Subject: Re: [RFC PATCH v2] mm: slub: print kernel addresses in slub debug
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References: <20190809010837.24166-1-miles.chen@mediatek.com>
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 <1565359918.12824.20.camel@mtkswgap22>
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On Fri, Aug 09, 2019 at 10:11:58PM +0800, Miles Chen wrote:
> On Thu, 2019-08-08 at 19:46 -0700, Matthew Wilcox wrote:
> > On Fri, Aug 09, 2019 at 09:08:37AM +0800, miles.chen@mediatek.com wrote:
> > > INFO: Slab 0x(____ptrval____) objects=25 used=10 fp=0x(____ptrval____)
> > 
> > ... you don't have any randomness on your platform?
> 
> We have randomized base on our platforms.

Look at initialize_ptr_random().  If you have randomness, then you
get a siphash_1u32() of the address.  With no randomness, you get this
___ptrval___ string instead.