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Subject: Re: [PATCH] numa: enforce iommu-off memory address limit
From: Michael Ellerman <michael@ellerman.id.au>
To: Milton Miller <miltonm@bga.com>
In-Reply-To: <111819287886b8b45671.846930886.miltonm@bga.com>
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Date: Sat, 16 Jun 2007 14:34:13 +1000
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On Fri, 2007-06-15 at 12:33 -0500, Milton Miller wrote:
> Don't short circuit the lmb_end_of_DRAM if iommu_is_off.
>=20
> If linux,iommu-off is in /chosen (because iommu=3Doff was on the command
> line), we limit the memory when adding it to the lmbs and page tables,
> but not when numa parses the device tree for numa affinity.  When we
> free bootmem, we then try to use these pages without mapping them or
> allocating supporting data structures resulting in bad_page and/or data
> storage interrupts.
>=20
> Signed-off-by: Milton Miller <miltonm@bga.com>
> ---=20
> Paul, I think this can wait for 2.6.23 although its small enough
> if you want to send it for 2.6.22.
>=20
> Index: kernel/arch/powerpc/mm/numa.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> --- kernel.orig/arch/powerpc/mm/numa.c	2007-06-15 01:10:19.000000000 -050=
0
> +++ kernel/arch/powerpc/mm/numa.c	2007-06-15 01:41:32.000000000 -0500
> @@ -21,6 +21,7 @@
>  #include <asm/lmb.h>
>  #include <asm/system.h>
>  #include <asm/smp.h>
> +#include <asm/iommu.h>
> =20
>  static int numa_enabled =3D 1;
> =20
> @@ -286,7 +287,7 @@ static unsigned long __init numa_enforce
>  	 * having memory holes below the limit.
>  	 */
> =20
> -	if (! memory_limit)
> +	if (!memory_limit && !iommu_is_off)
>  		return size;

I'd rather just remove the check entirely, and rename the routine -
numa_check_end_of_ram() or something.

cheers


--=20
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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