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Date: Wed, 16 Apr 2008 02:44:30 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Pekka Enberg <penberg@cs.helsinki.fi>,
       Christoph Lameter <clameter@sgi.com>, linux-kernel@vger.kernel.org,
       Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@suse.de>,
       Andrew Morton <akpm@linux-foundation.org>,
       "Rafael J. Wysocki" <rjw@sisk.pl>, apw@shadowen.org,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [patch] mm: sparsemem memory_present() memory corruption fix
Message-ID: <20080416004430.GA26928@elte.hu>
References: <Pine.LNX.4.64.0804151232080.1785@schroedinger.engr.sgi.com> <20080415195430.GA23015@elte.hu> <Pine.LNX.4.64.0804151255390.1785@schroedinger.engr.sgi.com> <20080415201734.GA25628@elte.hu> <4805115D.5030703@cs.helsinki.fi> <20080415204025.GA29784@elte.hu> <alpine.LFD.1.00.0804151353380.2879@woody.linux-foundation.org> <20080416000356.GA24737@elte.hu> <20080416001816.GA26295@elte.hu> <86802c440804151732j519a541t9d8e4f6b49a53313@mail.gmail.com>
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* Yinghai Lu <yhlu.kernel@gmail.com> wrote:

> >  +       unsigned long max_arch_pfn = 1ULL << (MAX_PHYSMEM_BITS-PAGE_SHIFT);
> >
> >  and also check my analysis whether it is correct and whether it 
> >  matches the reported bug patterns. But otherwise the fix looks like 
> >  a safe fix for v2.6.25-final to me - it only filters out values 
> >  from sparsemem input that are nonsensical in the sparsemem 
> >  framework anyway.
> 
> can you check why find_max_pfn() e820_32.c need to call 
> memory_present? wonder if it can be removed.

this is the only call to memory_present() we do in 32-bit arch setup, so 
it's required.

(the function find_max_pfn() is woefully misnamed, but that's a cleanup 
- i just fixed this in x86.git.)

	Ingo