linux-kernel - RE: [PATCH] ARM: sparsemem: allow pfn_valid to be overridden when using SPARSEMEM

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Message-ID: <1305795912.29560.19.camel@e102144-lin.cambridge.arm.com>
Date:	Thu, 19 May 2011 10:05:12 +0100
From:	Will Deacon <will.deacon@....com>
To:	H Hartley Sweeten <hartleys@...ionengravers.com>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Russell King <linux@....linux.org.uk>,
	Mel Gorman <mgorman@...e.de>
Subject: RE: [PATCH] ARM: sparsemem: allow pfn_valid to be overridden when
 using	SPARSEMEM

On Wed, 2011-05-18 at 19:53 +0100, H Hartley Sweeten wrote:
> On Wednesday, May 18, 2011 9:04 AM, Will Deacon wrote:
> >
> > In commit eb33575c ("[ARM] Double check memmap is actually valid with a
> > memmap has unexpected holes V2"), a new function, memmap_valid_within,
> > was introduced to mmzone.h so that holes in the memmap which pass
> > pfn_valid in SPARSEMEM configurations can be detected and avoided.

[...]

> I tested this on an EP93xx based system which uses ARCH_HAS_HOLES_MEMORYMODEL.
> The EP9307A has 64MB of memory that appears as two 32MB blocks at addresses
> 0xc0000000 and 0xc4000000.  Currently the EP93xx uses a Flat Memory model and
> the hole used to cause a Kernel OOPs before commit e80d6a24 ("[ARM] Skip memory
> holes in FLATMEM when reading /proc/pagetypeinfo"), which is where I think this
> all started.
> 
[...]

> I'm not sure what the output "should" be, but the patch does not seem to
> cause any issues.  So feel free to add:
> 
> Tested-by: H Hartley Sweeten <hsweeten@...ionengravers.com>

Thanks for that. It's good to know that this patch doesn't break
non-sparsemem platforms with whacky flatmem configurations :)

Will


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