[PATCH v7 04/10] mm: thp: introduce CONFIG_ARCH_ENABLE_THP_MIGRATION

[Zi Yan]

From: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>

Introduces CONFIG_ARCH_ENABLE_THP_MIGRATION to limit thp migration
functionality to x86_64, which should be safer at the first step.

ChangeLog v1 -> v2:
- fixed config name in subject and patch description

Signed-off-by: Naoya Horiguchi <n-horigu...@ah.jp.nec.com>
Reviewed-by: Anshuman Khandual <khand...@linux.vnet.ibm.com>
---
 arch/x86/Kconfig        |  4 ++++
 include/linux/huge_mm.h | 10 ++++++++++
 mm/Kconfig              |  3 +++
 3 files changed, 17 insertions(+)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b6373817e6f4..631af221ce63 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2276,6 +2276,10 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION
        def_bool y
        depends on X86_64 && HUGETLB_PAGE && MIGRATION
 
+config ARCH_ENABLE_THP_MIGRATION
+       def_bool y
+       depends on X86_64 && TRANSPARENT_HUGEPAGE
+
 menu "Power management and ACPI options"
 
 config ARCH_HIBERNATION_HEADER
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index ee696347f928..d8f35a0865dc 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -233,6 +233,11 @@ void mm_put_huge_zero_page(struct mm_struct *mm);
 
 #define mk_huge_pmd(page, prot) pmd_mkhuge(mk_pmd(page, prot))
 
+static inline bool thp_migration_supported(void)
+{
+       return IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION);
+}
+
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
 #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
 #define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; })
@@ -336,6 +341,11 @@ static inline struct page *follow_devmap_pud(struct 
vm_area_struct *vma,
 {
        return NULL;
 }
+
+static inline bool thp_migration_supported(void)
+{
+       return false;
+}
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 
 #endif /* _LINUX_HUGE_MM_H */
diff --git a/mm/Kconfig b/mm/Kconfig
index 9bf2055ed061..6634e0ed5c1b 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -262,6 +262,9 @@ config MIGRATION
 config ARCH_ENABLE_HUGEPAGE_MIGRATION
        bool
 
+config ARCH_ENABLE_THP_MIGRATION
+       bool
+
 config PHYS_ADDR_T_64BIT
        def_bool 64BIT || ARCH_PHYS_ADDR_T_64BIT
 
-- 
2.11.0