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Date: Fri, 09 Dec 2011 15:44:53 -0500
From: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
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To: Andrew Morton <akpm@linux-foundation.org>
CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
        Hugh Dickins <hughd@google.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Shaohua Li <shaohua.li@intel.com>
Subject: Re: [PATCH] mm: simplify find_vma_prev
References: <1323461345-12805-1-git-send-email-kosaki.motohiro@gmail.com> <20111209122406.11f9e31a.akpm@linux-foundation.org>
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> This changes the (undocumented, naturally) interface in disturbing ways.
>
> Currently, *pprev will always be written to.  With this change, *pprev
> will only be written to if find_vma_prev() returns non-NULL.
>
> Looking through the code, this is mostly benign.  But it will cause the
> CONFIG_STACK_GROWSUP version of find_extend_vma() to use an
> uninitialised stack slot in ways which surely will crash the kernel.

Weird.


> So please have a think about that and fix it up.  And please add
> documentation for find_vma_prev()'s interface so we don't break it next
> time.

Sure thing. Thank you for good spotting!