[PATCH v2 12/16] mm/vmemmap optimization: Split hugetlb and devdax vmemmap optimization

[Aneesh Kumar K.V]

Arm disabled hugetlb vmemmap optimization [1] because hugetlb vmemmap
optimization includes an update of both the permissions (writeable to
read-only) and the output address (pfn) of the vmemmap ptes. That is not
supported without unmapping of pte(marking it invalid) by some
architectures.

With DAX vmemmap optimization we don't require such pte updates and
architectures can enable DAX vmemmap optimization while having hugetlb
vmemmap optimization disabled. Hence split DAX optimization support into a
different config.

loongarch and riscv don't have devdax support. So the DAX config is not
enabled for them. With this change, arm64 should be able to select DAX
optimization

[1] commit 060a2c92d1b6 ("arm64: mm: hugetlb: Disable HUGETLB_PAGE_OPTIMIZE_VMEMMAP")

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
---
 arch/loongarch/Kconfig | 2 +-
 arch/riscv/Kconfig     | 2 +-
 arch/x86/Kconfig       | 3 ++-
 fs/Kconfig             | 2 +-
 include/linux/mm.h     | 2 +-
 mm/Kconfig             | 5 ++++-
 6 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index d38b066fc931..2060990c4612 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -55,7 +55,7 @@ config LOONGARCH
 	select ARCH_USE_QUEUED_SPINLOCKS
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
 	select ARCH_WANT_LD_ORPHAN_WARN
-	select ARCH_WANT_OPTIMIZE_VMEMMAP
+	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 	select ARCH_WANTS_NO_INSTR
 	select BUILDTIME_TABLE_SORT
 	select COMMON_CLK
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5966ad97c30c..d8f3765ff115 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -50,7 +50,7 @@ config RISCV
 	select ARCH_WANT_GENERAL_HUGETLB if !RISCV_ISA_SVNAPOT
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select ARCH_WANT_LD_ORPHAN_WARN if !XIP_KERNEL
-	select ARCH_WANT_OPTIMIZE_VMEMMAP
+	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
 	select BUILDTIME_TABLE_SORT if MMU
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 53bab123a8ee..eb383960b6ee 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -127,7 +127,8 @@ config X86
 	select ARCH_WANT_GENERAL_HUGETLB
 	select ARCH_WANT_HUGE_PMD_SHARE
 	select ARCH_WANT_LD_ORPHAN_WARN
-	select ARCH_WANT_OPTIMIZE_VMEMMAP	if X86_64
+	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP	if X86_64
+	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP	if X86_64
 	select ARCH_WANTS_THP_SWAP		if X86_64
 	select ARCH_HAS_PARANOID_L1D_FLUSH
 	select BUILDTIME_TABLE_SORT
diff --git a/fs/Kconfig b/fs/Kconfig
index 18d034ec7953..9c104c130a6e 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -252,7 +252,7 @@ config HUGETLB_PAGE
 
 config HUGETLB_PAGE_OPTIMIZE_VMEMMAP
 	def_bool HUGETLB_PAGE
-	depends on ARCH_WANT_OPTIMIZE_VMEMMAP
+	depends on ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 	depends on SPARSEMEM_VMEMMAP
 
 config HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9a45e61cd83f..6e56ae09f0c1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3553,7 +3553,7 @@ void vmemmap_free(unsigned long start, unsigned long end,
 #endif
 
 #define VMEMMAP_RESERVE_NR	2
-#ifdef CONFIG_ARCH_WANT_OPTIMIZE_VMEMMAP
+#ifdef CONFIG_ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
 static inline bool __vmemmap_can_optimize(struct vmem_altmap *altmap,
 					  struct dev_pagemap *pgmap)
 {
diff --git a/mm/Kconfig b/mm/Kconfig
index 7672a22647b4..7b388c10baab 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -461,7 +461,10 @@ config SPARSEMEM_VMEMMAP
 # Select this config option from the architecture Kconfig, if it is preferred
 # to enable the feature of HugeTLB/dev_dax vmemmap optimization.
 #
-config ARCH_WANT_OPTIMIZE_VMEMMAP
+config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
+	bool
+
+config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 	bool
 
 config HAVE_MEMBLOCK_PHYS_MAP
-- 
2.40.1