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Date: Thu, 29 Jan 2015 15:12:54 -0800
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH v10 13/17] mm: vmalloc: add flag preventing guard hole
 allocation
Message-Id: <20150129151254.edc75e5ae20c3cafb55d88b1@linux-foundation.org>
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To: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: linux-kernel@vger.kernel.org, Dmitry Vyukov <dvyukov@google.com>, Konstantin Serebryany <kcc@google.com>, Dmitry Chernenkov <dmitryc@google.com>, Andrey Konovalov <adech.fo@gmail.com>, Yuri Gribov <tetra2005@gmail.com>, Konstantin Khlebnikov <koct9i@gmail.com>, Sasha Levin <sasha.levin@oracle.com>, Christoph Lameter <cl@linux.com>, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Dave Hansen <dave.hansen@intel.com>, Andi Kleen <andi@firstfloor.org>, x86@kernel.org, linux-mm@kvack.org

On Thu, 29 Jan 2015 18:11:57 +0300 Andrey Ryabinin <a.ryabinin@samsung.com> wrote:

> For instrumenting global variables KASan will shadow memory
> backing memory for modules. So on module loading we will need
> to allocate shadow memory and map it at exact virtual address.

I don't understand.  What does "map it at exact virtual address" mean?

> __vmalloc_node_range() seems like the best fit for that purpose,
> except it puts a guard hole after allocated area.

Why is the guard hole a problem?

More details needed in this changelog, please.


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