linux-kernel - Re: [RFC BUG?] dereference PAGE

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Message-ID: <20070502163244.GA26598@holomorphy.com>
Date:	Wed, 2 May 2007 09:32:44 -0700
From:	Bill Irwin <bill.irwin@...cle.com>
To:	Jeremy Fitzhardinge <jeremy@...p.org>
Cc:	Bill Irwin <bill.irwin@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Kruchinin <dubalom@...il.com>,
	linux-kernel@...r.kernel.org,
	Jeremy Fitzhardinge <jeremy@...source.com>,
	Andi Kleen <ak@...e.de>, Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>, wli@...omorphy.com
Subject: Re: [RFC BUG?] dereference PAGE_OFFSET address (rc7-mm2)

Bill Irwin wrote:
>> Brain dump before crashing for the night:
>> The patch refuses to clobber already-present pagetable entries of
>> whatever origin. There are pagetables prior to this setup covering the
>> address range just above PAGE_OFFSET. If this theory is correct, you
>> should only be able to go a few MB above PAGE_OFFSET before encountering
>> unreadable kernel memory. IIRC those pagetables are a statically
>> allocated array in assembly; altering that array to set supervisor bits
>> may resolve it, though it may also be freed as initmem.

On Wed, May 02, 2007 at 09:28:46AM -0700, Jeremy Fitzhardinge wrote:
> I think this should be fixed now.  Eric made all those writes
> unconditional (to fix a problem with PSE superpages not being created). 
> The patch is in Andi's queue.

It needs verification with the testcase from this thread.


-- wli
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