[RFC PATCH v2 10/11] ARM64: mm: Raise MAX_ORDER for 64KB pages and THP.

[Steve Capper]

The buddy allocator has a default MAX_ORDER of 11, which is too
low to allocate enough memory for 512MB Transparent HugePages if
our base page size is 64KB.

This patch introduces MAX_ZONE_ORDER and sets it to 14 when 64KB
pages are used in conjuction with THP, otherwise the default value
of 11 is used.

Signed-off-by: Steve Capper <steve.capper at linaro.org>
---
 arch/arm64/Kconfig | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 053533b..a5f76cf 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -196,6 +196,11 @@ config ARCH_WANT_HUGE_PMD_SHARE
 
 source "mm/Kconfig"
 
+config FORCE_MAX_ZONEORDER
+	int
+	default "14" if (ARM64_64K_PAGES && TRANSPARENT_HUGEPAGE)
+	default "11"
+
 endmenu
 
 menu "Boot options"
-- 
1.8.1.4