thp, x86: introduce HAVE_ARCH_TRANSPARENT_HUGEPAGE

Cleanup patch in preparation for transparent hugepage support on s390.
Adding new architectures to the TRANSPARENT_HUGEPAGE config option can
make the "depends" line rather ugly, like "depends on (X86 || (S390 &&
64BIT)) && MMU".

This patch adds a HAVE_ARCH_TRANSPARENT_HUGEPAGE instead.  x86 already has
MMU "def_bool y", so the MMU check is superfluous there and
HAVE_ARCH_TRANSPARENT_HUGEPAGE can be selected in arch/x86/Kconfig.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 5 insertions, 1 deletions

diff --git a/arch/Kconfig b/arch/Kconfig
index a62965d057f6..550cce4dd648 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -313,4 +313,7 @@ config HAVE_IRQ_TIME_ACCOUNTING
           Archs need to ensure they use a high enough resolution clock to
           support irq time accounting and then call enable_sched_clock_irqtime().
 
+config HAVE_ARCH_TRANSPARENT_HUGEPAGE
+        bool
+
 source "kernel/gcov/Kconfig"
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6119d6c7002e..1ae94bcae5d9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -88,6 +88,7 @@ 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
diff --git a/mm/Kconfig b/mm/Kconfig
index d5c8019c6627..3322342a1ffb 100644
--- a/mm/Kconfig
+++ b/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