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SubjectRe: [origin tree build failure] Re: [PULL] Please pull hwpoison code for 2.6.32
On Sat, Sep 26, 2009 at 09:35:07AM -0700, Linus Torvalds 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.

That's a reasonable solution, but I would prefer to do it the other way round
(MEMORY_FAILURE disabling NUMA) to minimize user confusion. Also it's not
enough to just do NUMAQ, but needs all of 32bit NUMA, otherwise the NODES_SHIFT
could be set too high again.

Here's a compile tested patch (don't have a NUMAQ) implementing this:

---
x86: Don't allow 32bit NUMA together with hwpoison to avoid page flags overflow

From: Andi Kleen <ak@linux.intel.com>

Otherwise the enlarged sparsemem field in page->flags overflows 32bit,
which breaks compilation.

Reported by Ingo Molnar.
Originally based on a patch from Linus.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 9369879..384a897 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -423,6 +423,7 @@ config X86_32_NON_STANDARD
config X86_NUMAQ
bool "NUMAQ (IBM/Sequent)"
depends on X86_32_NON_STANDARD
+ depends on !MEMORY_FAILURE
select NUMA
select X86_MPPARSE
---help---
@@ -1108,6 +1109,7 @@ config NUMA
bool "Numa Memory Allocation and Scheduler Support"
depends on SMP
depends on X86_64 || (X86_32 && HIGHMEM64G && (X86_NUMAQ || X86_BIGSMP || X86_SUMMIT && ACPI) && EXPERIMENTAL)
+ depends on !X86_32 || !MEMORY_FAILURE
default y if (X86_NUMAQ || X86_SUMMIT || X86_BIGSMP)
---help---
Enable NUMA (Non Uniform Memory Access) support.
@@ -1125,6 +1127,9 @@ config NUMA

Otherwise, you should say N.

+comment "32bit NUMA support requires disabling MEMORY_FAILURE"
+ depends on X86_32 && MEMORY_FAILURE
+
comment "NUMA (Summit) requires SMP, 64GB highmem support, ACPI"
depends on X86_32 && X86_SUMMIT && (!HIGHMEM64G || !ACPI)


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