From 53fa117bb33c9ebc4c0746b3830e273f5e9b97b7 Mon Sep 17 00:00:00 2001 From: Anshuman Khandual Date: Wed, 9 Sep 2020 10:23:03 +0530 Subject: [PATCH] arm64/mm: Enable THP migration In certain page migration situations, a THP page can be migrated without being split into it's constituent subpages. This saves time required to split a THP and put it back together when required. But it also saves an wider address range translation covered by a single TLB entry, reducing future page fault costs. A previous patch changed platform THP helpers per generic memory semantics, clearing the path for THP migration support. This adds two more THP helpers required to create PMD migration swap entries. Now enable THP migration via ARCH_ENABLE_THP_MIGRATION. Signed-off-by: Anshuman Khandual Reviewed-by: Catalin Marinas Cc: Catalin Marinas Cc: Will Deacon Cc: Mark Rutland Cc: Marc Zyngier Cc: Suzuki Poulose Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Link: https://lore.kernel.org/r/1599627183-14453-3-git-send-email-anshuman.khandual@arm.com Signed-off-by: Will Deacon --- arch/arm64/Kconfig | 4 ++++ arch/arm64/include/asm/pgtable.h | 5 +++++ 2 files changed, 9 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6d23283..e21b940 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1876,6 +1876,10 @@ config ARCH_ENABLE_HUGEPAGE_MIGRATION def_bool y depends on HUGETLB_PAGE && MIGRATION +config ARCH_ENABLE_THP_MIGRATION + def_bool y + depends on TRANSPARENT_HUGEPAGE + menu "Power management options" source "kernel/power/Kconfig" diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index d8258ae..bc68da9 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -875,6 +875,11 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, #define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val(pte) }) #define __swp_entry_to_pte(swp) ((pte_t) { (swp).val }) +#ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION +#define __pmd_to_swp_entry(pmd) ((swp_entry_t) { pmd_val(pmd) }) +#define __swp_entry_to_pmd(swp) __pmd((swp).val) +#endif /* CONFIG_ARCH_ENABLE_THP_MIGRATION */ + /* * Ensure that there are not more swap files than can be encoded in the kernel * PTEs. -- 2.7.4