[PATCH 1/4] mm: generalize vmemmap remap architecture support

[Muchun Song]

ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP is named after its first user, but
the underlying requirement is not HugeTLB-specific. Generic MM only needs
to know whether an architecture can safely remap populated vmemmap PTEs at
run time.

Rename the architecture opt-in to ARCH_SUPPORTS_VMEMMAP_REMAP and make
HugeTLB vmemmap optimization depend on that generic capability. This also
prepares for FS-DAX vmemmap optimization, which relies on the same runtime
remap support.

Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
---
 arch/loongarch/Kconfig | 2 +-
 arch/riscv/Kconfig     | 2 +-
 arch/x86/Kconfig       | 2 +-
 fs/Kconfig             | 2 +-
 mm/Kconfig             | 6 ++++--
 5 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 9c5def706222..e9bf19172e86 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -72,6 +72,7 @@ config LOONGARCH
 	select ARCH_SUPPORTS_RT
 	select ARCH_SUPPORTS_SCHED_SMT if SMP
 	select ARCH_SUPPORTS_SCHED_MC  if SMP
+	select ARCH_SUPPORTS_VMEMMAP_REMAP if 64BIT
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_USE_MEMTEST
@@ -80,7 +81,6 @@ config LOONGARCH
 	select ARCH_WANT_DEFAULT_BPF_JIT if HAVE_EBPF_JIT
 	select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT
 	select ARCH_WANT_LD_ORPHAN_WARN
-	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if 64BIT
 	select ARCH_WANTS_NO_INSTR
 	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select BUILDTIME_TABLE_SORT
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 5965666194b0..3614001cafdb 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -76,6 +76,7 @@ config RISCV
 	select ARCH_SUPPORTS_RT
 	select ARCH_SUPPORTS_SHADOW_CALL_STACK if HAVE_SHADOW_CALL_STACK
 	select ARCH_SUPPORTS_SCHED_MC if SMP
+	select ARCH_SUPPORTS_VMEMMAP_REMAP
 	select ARCH_USE_CMPXCHG_LOCKREF if 64BIT
 	select ARCH_USE_MEMTEST
 	select ARCH_USE_QUEUED_RWLOCKS
@@ -88,7 +89,6 @@ config RISCV
 	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT
 	select ARCH_WANT_LD_ORPHAN_WARN
 	select ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
-	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
 	select ARCH_WANTS_NO_INSTR
 	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
 	select ARCH_WEAK_RELEASE_ACQUIRE if ARCH_USE_QUEUED_SPINLOCKS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index a8c3b3d31a27..53f72d1500c5 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -133,6 +133,7 @@ config X86
 	select ARCH_SUPPORTS_LTO_CLANG
 	select ARCH_SUPPORTS_LTO_CLANG_THIN
 	select ARCH_SUPPORTS_RT
+	select ARCH_SUPPORTS_VMEMMAP_REMAP	if X86_64
 	select ARCH_USE_BUILTIN_BSWAP
 	select ARCH_USE_CMPXCHG_LOCKREF
 	select ARCH_USE_MEMTEST
@@ -148,7 +149,6 @@ config X86
 	select ARCH_WANT_HUGE_PMD_SHARE		if X86_64
 	select ARCH_WANT_LD_ORPHAN_WARN
 	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 ARCH_WANT_IRQS_OFF_ACTIVATE_MM
diff --git a/fs/Kconfig b/fs/Kconfig
index d1c210c6508f..655795fbbd1b 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -276,7 +276,7 @@ config HUGETLB_PAGE
 
 config HUGETLB_PAGE_OPTIMIZE_VMEMMAP
 	def_bool HUGETLB_PAGE
-	depends on ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
+	depends on ARCH_SUPPORTS_VMEMMAP_REMAP
 	depends on SPARSEMEM_VMEMMAP
 
 config HUGETLB_PMD_PAGE_TABLE_SHARING
diff --git a/mm/Kconfig b/mm/Kconfig
index c1ddf59c0d71..7ec734d89beb 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -463,12 +463,14 @@ 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.
+# to enable the feature of dev_dax vmemmap optimization.
 #
 config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
 	bool
 
-config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
+# Select this from architectures where generic MM can safely remap populated
+# vmemmap PTEs at run time.
+config ARCH_SUPPORTS_VMEMMAP_REMAP
 	bool
 
 config HAVE_MEMBLOCK_PHYS_MAP
-- 
2.54.0