mm/vmemmap optimization: split hugetlb and devdax vmemmap optimization

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.

s390, 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")

Link: https://lkml.kernel.org/r/20230724190759.483013-8-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index e71d5bf..dc56ddf 100644 (file)
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -60,7 +60,7 @@ 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 4c07b91..6943d34 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -53,7 +53,7 @@ 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/s390/Kconfig b/arch/s390/Kconfig
index 290b6f9..8ff6d1c 100644 (file)
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -127,7 +127,7 @@ config S390
        select ARCH_WANTS_NO_INSTR
        select ARCH_WANT_DEFAULT_BPF_JIT
        select ARCH_WANT_IPC_PARSE_VERSION
-       select ARCH_WANT_OPTIMIZE_VMEMMAP
+       select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
        select BUILDTIME_TABLE_SORT
        select CLONE_BACKWARDS2
        select DMA_OPS if PCI

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 7422db4..78224aa 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -128,7 +128,8 @@ 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 19975b1..f3be721 100644 (file)
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -254,7 +254,7 @@ 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 d4ce73c..b2520dd 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3633,7 +3633,7 @@ 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 22acffd..1959d04 100644 (file)
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -487,7 +487,10 @@ 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