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From: Mel Gorman <mel@csn.ul.ie>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-kernel@vger.kernel.org, Bob Picco <bob.picco@hp.com>,
	Dave Hansen <haveblue@us.ibm.com>,
	Andy Whitcroft <apw@shadowen.org>, Andi Kleen <ak@muc.de>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Keith Mannthey <kmannth@gmail.com>,
	"Luck, Tony" <tony.luck@intel.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
	Yasunori Goto <y-goto@jp.fujitsu.com>,
	akpm@linux-foundation.org, Linus Torvalds <torvalds@osdl.org>,
	ralf@linux-mips.org
Subject: Re: [PATCH] Fix crash with FLAT_MEMORY and ARCH_PFN_OFFSET != 0
Date: Thu, 20 Dec 2007 13:27:20 +0000	[thread overview]
Message-ID: <20071220132719.GA29857@csn.ul.ie> (raw)
In-Reply-To: <20071220124351.GA8880@alpha.franken.de>

On (20/12/07 13:43), Thomas Bogendoerfer didst pronounce:
> On Thu, Dec 20, 2007 at 11:44:06AM +0000, Mel Gorman wrote:
> > --- a/include/asm-mips/page.h
> > +++ b/include/asm-mips/page.h
> > @@ -37,13 +37,6 @@
> >  #include <linux/pfn.h>
> >  #include <asm/io.h>
> >  
> > -/*
> > - * It's normally defined only for FLATMEM config but it's
> > - * used in our early mem init code for all memory models.
> > - * So always define it.
> > - */
> > -#define ARCH_PFN_OFFSET		PFN_UP(PHYS_OFFSET)
> > -
> 
> hmm, doesn't this break what I've fixed ? Without this #define
> ARCH_PFN_OFFSET gets defined to 0 and the bug is back. Or did
> I miss anything ?
> 

ARCH_PFN_OFFSET goes to 0, so page_to_pfn() is no longer adjusting by
PFN_UP(PHYS_OFFSET) like it was when your problem occured. I am guessing
that the nature of the crash was that page_to_pfn() was returning bogus
values early in boot and trying to initialise memmap that didn't exist.

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab

  reply	other threads:[~2007-12-20 13:27 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-12-18 12:03 [PATCH] Fix crash with FLAT_MEMORY and ARCH_PFN_OFFSET != 0 Thomas Bogendoerfer
2007-12-18 12:24 ` Andrew Morton
2007-12-18 12:31   ` Thomas Bogendoerfer
2007-12-18 13:58 ` Mel Gorman
2007-12-18 16:09   ` Thomas Bogendoerfer
2007-12-20 11:44     ` Mel Gorman
2007-12-20 12:43       ` Thomas Bogendoerfer
2007-12-20 13:27         ` Mel Gorman [this message]
2007-12-30 11:37           ` Thomas Bogendoerfer
2008-01-07 12:15             ` Mel Gorman

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