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Subject[PATCH] x86: Fix hwpoison code related build failure on 32-bit NUMAQ

* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Sat, 26 Sep 2009, Andi Kleen wrote:
> >
> > Thanks for the report. The issue comes from NODES_SHIFT=4
> >
> > I think I tested the NUMA case, but perhaps not with full NODES_SHIFT.
> >
> > The easy fix would be to limit NODES_SHIFT to 3 for 32bit (8 nodes max). Do you
> > have any problems with that? I doubt there are any >8 nodes NUMAQs left.
> > (last time I heard the last machine at IBM was down to < 4)
>
> No, just say "we don't support HWPOISON on 32-bit NUMA".
>
> Maybe simply using something like this.
>
> TOTALLY UNTESTED!
>
> Linus
> ---
> arch/x86/Kconfig | 6 ++++++
> mm/Kconfig | 4 +++-
> 2 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 9369879..be1bb44 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -432,6 +432,12 @@ config X86_NUMAQ
> of Flat Logical. You will need a new lynxer.elf file to flash your
> firmware with - send email to <Martin.Bligh@us.ibm.com>.
>
> +config X86_SUPPORTS_MEMORY_FAILURE
> + bool
> + depends on !X86_NUMAQ
> + select ARCH_SUPPORTS_MEMORY_FAILURE
> + default y

Thanks Linus, this patch fixed the NUMAQ build problem.

Meanwhile i also found another similar build problem: sparsemem alone
triggers the build bug on 32-bit as well:

CONFIG_ARCH_SPARSEMEM_ENABLE=y
CONFIG_SPARSEMEM_MANUAL=y
CONFIG_SPARSEMEM=y
CONFIG_SPARSEMEM_STATIC=y

So i added that to the X86_SUPPORTS_MEMORY_FAILURE rules as well - with
that it works fine. (and this validates the concept of your patch as we
keep excluding a new kernel feature in a well-documented way instead of
narrowing existing hardware support with much less clear dependencies.)

I've attached the updated patch and will keep testing it a bit more
(there might be more corner cases). If it goes fine i can send it to you
via x86/urgent later today so that it gets into -rc1.

Can i add your signoff?

Ingo


------------------->
From 5e4000b6808ffca466f41c01442527f9fe4305bd Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 26 Sep 2009 09:35:07 -0700
Subject: [PATCH] x86: Fix hwpoison code related build failure on 32-bit NUMAQ
This build failure triggers:

In file included from include/linux/suspend.h:8,
from arch/x86/kernel/asm-offsets_32.c:11,
from arch/x86/kernel/asm-offsets.c:2:
include/linux/mm.h:503:2: error: #error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
Because due to the hwpoison page flag we ran out of page
flags on 32-bit.

Dont turn on hwpoison on 32-bit NUMA (it's rare in any
case).

Also clean up the Kconfig dependencies in the generic MM
code by introducing ARCH_SUPPORTS_MEMORY_FAILURE.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/Kconfig | 6 ++++++
mm/Kconfig | 4 +++-
2 files changed, 9 insertions(+), 1 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9369879..ef95406 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -432,6 +432,12 @@ config X86_NUMAQ
of Flat Logical. You will need a new lynxer.elf file to flash your
firmware with - send email to <Martin.Bligh@us.ibm.com>.

+config X86_SUPPORTS_MEMORY_FAILURE
+ bool
+ depends on (!X86_NUMAQ && !(X86_32 && SPARSEMEM))
+ select ARCH_SUPPORTS_MEMORY_FAILURE
+ default y
+
config X86_VISWS
bool "SGI 320/540 (Visual Workstation)"
depends on X86_32 && PCI && X86_MPPARSE && PCI_GODIRECT
diff --git a/mm/Kconfig b/mm/Kconfig
index 2477607..edd300a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -244,10 +244,12 @@ config DEFAULT_MMAP_MIN_ADDR
This value can be changed after boot using the
/proc/sys/vm/mmap_min_addr tunable.

+config ARCH_SUPPORTS_MEMORY_FAILURE
+ bool

config MEMORY_FAILURE
depends on MMU
- depends on X86_MCE
+ depends on ARCH_SUPPORTS_MEMORY_FAILURE
bool "Enable recovery from hardware memory errors"
help
Enables code to recover from some memory failures on systems

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