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Date: Thu, 30 Dec 2010 22:25:25 +0100
Message-ID: <AANLkTi=ZuOJ07yN-nqso_pX_NS90eKrPD=vG9-_a59vG@mail.gmail.com>
Subject: Re: kernel BUG at /build/buildd/linux-2.6.35/mm/filemap.c:128!
From: =?UTF-8?B?Um9iZXJ0IMWad2nEmWNraQ==?= <robert@swiecki.net>
To: Hugh Dickins <hughd@google.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
        Andrew Morton <akpm@linux-foundation.org>,
        Nick Piggin <npiggin@kernel.dk>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
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>> I guess the latter is the more likely: maybe the truncate_count/restart
>> logic isn't working properly.  I'll try to check over that again later -
>> but will be happy if someone else beats me to it.
>
> I have since found an omission in the restart_addr logic: looking back
> at the October 2004 history of vm_truncate_count, I see that originally
> I designed it to work one way, but hurriedly added a 7/6 redesign when
> vma splitting turned out to leave an ambiguity.  I should have updated
> the protection in mremap move at that time, but missed it.
>
> Robert, please try out the patch below (should apply fine to 2.6.35):

In the beginning  of Jan (3-4) at earliest I'm afraid, i.e. when I
manage to get to my console-over-rs232 setup.

> I'm hoping this will fix what the fuzzer found, but it's still quite
> possible that it found something else wrong that I've not yet noticed.
> The patch could probably be cleverer (if we exported the notion of
> restart_addr out of mm/memory.c), but I'm more in the mood for being
> safe than clever at the moment.

-- 
Robert Święcki
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