Re: [PATCH 3/3] mm: Introduce HAVE_ARCH_TRANSPARENT_HUGEPAGE

From: Andrew Morton
Date: Thu Sep 13 2012 - 17:40:19 EST


On Fri, 14 Sep 2012 07:27:32 +1000
Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:

> Hi Andrew,
>
> On Thu, 13 Sep 2012 12:05:14 -0700 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > diff -puN arch/x86/Kconfig~mm-introduce-have_arch_transparent_hugepage arch/x86/Kconfig
> > --- a/arch/x86/Kconfig~mm-introduce-have_arch_transparent_hugepage
> > +++ a/arch/x86/Kconfig
> > @@ -83,7 +83,6 @@ config X86
> > select IRQ_FORCED_THREADING
> > select USE_GENERIC_SMP_HELPERS if SMP
> > select HAVE_BPF_JIT if X86_64
> > - select HAVE_ARCH_TRANSPARENT_HUGEPAGE
>
> Why not
> select HAVE_ARCH_TRANSPARENT_HUGEPAGE if MMU
>

Well, this is in arch/x86/Kconfig, where MMU is known to always be set.

Yes, I think Gerald's patch will suffice:

--- a/arch/Kconfig~thp-x86-introduce-have_arch_transparent_hugepage
+++ a/arch/Kconfig
@@ -326,4 +326,7 @@ config HAVE_RCU_USER_QS
are already protected inside rcu_irq_enter/rcu_irq_exit() but
preemption or signal handling on irq exit still need to be protected.

+config HAVE_ARCH_TRANSPARENT_HUGEPAGE
+ bool
+
source "kernel/gcov/Kconfig"
--- a/arch/x86/Kconfig~thp-x86-introduce-have_arch_transparent_hugepage
+++ a/arch/x86/Kconfig
@@ -83,6 +83,7 @@ config X86
select IRQ_FORCED_THREADING
select USE_GENERIC_SMP_HELPERS if SMP
select HAVE_BPF_JIT if X86_64
+ select HAVE_ARCH_TRANSPARENT_HUGEPAGE
select CLKEVT_I8253
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select GENERIC_IOMAP
--- a/mm/Kconfig~thp-x86-introduce-have_arch_transparent_hugepage
+++ a/mm/Kconfig
@@ -318,7 +318,7 @@ config NOMMU_INITIAL_TRIM_EXCESS

config TRANSPARENT_HUGEPAGE
bool "Transparent Hugepage Support"
- depends on X86 && MMU
+ depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
select COMPACTION
help
Transparent Hugepages allows the kernel to use huge pages and
_

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