[RFC 2/3] arm64/hugetlb: Enable HUGETLB_PAGE_SIZE_VARIABLE

[Anshuman Khandual]

MAX_ORDER which invariably depends on FORCE_MAX_ZONEORDER can be a variable
for a given page size, depending on whether TRANSPARENT_HUGEPAGE is enabled
or not. In certain page size and THP combinations HUGETLB_PAGE_ORDER can be
greater than MAX_ORDER, making it unusable as pageblock_order.

This enables HUGETLB_PAGE_SIZE_VARIABLE making pageblock_order a variable
rather than the compile time constant HUGETLB_PAGE_ORDER which could break
MAX_ORDER rule for certain configurations.

Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
 arch/arm64/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 175914f2f340..c4acf8230f20 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1918,6 +1918,10 @@ config ARCH_ENABLE_THP_MIGRATION
 	def_bool y
 	depends on TRANSPARENT_HUGEPAGE
 
+config HUGETLB_PAGE_SIZE_VARIABLE
+	def_bool y
+	depends on HUGETLB_PAGE
+
 menu "Power management options"
 
 source "kernel/power/Kconfig"
-- 
2.20.1