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Message-ID: <84144f020809030235p14f71915v355102005add6c5a@mail.gmail.com>
Date: Wed, 3 Sep 2008 12:35:43 +0300
From: "Pekka Enberg" <penberg@cs.helsinki.fi>
To: "Steve VanDeBogart" <vandebo-lkml@nerdbox.net>
Subject: Re: [uml-devel] [PATCH 4/6] VM: Annotate pagealloc
Cc: jiayingz@google.com, linux-kernel@vger.kernel.org,
       user-mode-linux-devel@lists.sourceforge.net, dkegel@google.com,
       "Vegard Nossum" <vegard.nossum@gmail.com>,
       "Ingo Molnar" <mingo@elte.hu>
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Hi Steve,

On Wed, Sep 3, 2008 at 8:25 AM, Steve VanDeBogart
<vandebo-lkml@nerdbox.net> wrote:
>>> Index: linux-2.6.27-rc5/mm/page_alloc.c
>>> @@ -1080,6 +1081,7 @@
>>>               if (!page)
>>>                       goto failed;
>>>       }
>>> +       VALGRIND_MAKE_MEM_UNDEFINED(page_address(page), PAGE_SIZE <<
>>> order);
>>
>> No SHOUTING macros please, and I think you should just pass page and
>> order here and do the calculation elsewhere.
>
> Valgrind provides a header file that defines these annotation functions.
> For the ease of tracking changes to this header file, I've made minimal
> changes to it (just a couple lines to integrate with Kconfig).  If the
> interfaces and/or style is objectionable to the kernel community at
> large, than we will have to decide to either wrap the interface that
> Valgrind provides or modify the header and track changes manually.

That's trivially fixable by adding a wrapper for the ugly valgrind
macros and hiding that in some header file. Preferably something
similar to what the kmemcheck hooks look like so that we can also use
them in the future if we implement tracking at page allocator level
too.

                                 Pekka