mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE

Patch series "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup
CONFIG_MIGRATION".

While working on memory hotplug code cleanups, I realized that
CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE is not really required anymore.

Changing that revealed some rather nasty looking CONFIG_MIGRATION
handling.

Let's clean that up by introducing a dedicated CONFIG_NUMA_MIGRATION
option and reducing the dependencies that CONFIG_MIGRATION has.


This patch (of 2):

All architectures that select CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE also
select CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG.  So we can just remove
CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE.

For CONFIG_MIGRATION, make it depend on CONFIG_MEMORY_HOTREMOVE instead,
and make CONFIG_MEMORY_HOTREMOVE select CONFIG_MIGRATION (just like
CONFIG_CMA and CONFIG_COMPACTION already do).

We'll clean up CONFIG_MIGRATION next.

Link: https://lkml.kernel.org/r/20260319-config_migration-v1-0-42270124966f@kernel.org
Link: https://lkml.kernel.org/r/20260319-config_migration-v1-1-42270124966f@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/arm64/Kconfig

@@ -16,7 +16,6 @@ config ARM64
 	select ARCH_BINFMT_ELF_STATE
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_MEMORY_HOTPLUG
-	select ARCH_ENABLE_MEMORY_HOTREMOVE
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_CACHE_LINE_SIZE

arch/loongarch/Kconfig

@@ -12,7 +12,6 @@ config LOONGARCH
 	select ARCH_NEEDS_DEFER_KASAN
 	select ARCH_DISABLE_KASAN_INLINE
 	select ARCH_ENABLE_MEMORY_HOTPLUG
-	select ARCH_ENABLE_MEMORY_HOTREMOVE
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
 	select ARCH_HAS_CPU_FINALIZE_INIT

arch/powerpc/Kconfig

@@ -126,7 +126,6 @@ config PPC
 	select ARCH_DISABLE_KASAN_INLINE	if PPC_RADIX_MMU
 	select ARCH_DMA_DEFAULT_COHERENT	if !NOT_COHERENT_CACHE
 	select ARCH_ENABLE_MEMORY_HOTPLUG
-	select ARCH_ENABLE_MEMORY_HOTREMOVE
 	select ARCH_HAS_COPY_MC			if PPC64
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL

arch/riscv/Kconfig

@@ -21,7 +21,6 @@ config RISCV
 	select ARCH_DMA_DEFAULT_COHERENT
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM_VMEMMAP
-	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_BINFMT_FLAT

arch/s390/Kconfig

@@ -85,7 +85,6 @@ config S390
 	select ARCH_32BIT_USTAT_F_TINODE
 	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
 	select ARCH_ENABLE_MEMORY_HOTPLUG if SPARSEMEM
-	select ARCH_ENABLE_MEMORY_HOTREMOVE
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_CC_CAN_LINK

arch/x86/Kconfig

@@ -69,7 +69,6 @@ config X86
 	select ARCH_CORRECT_STACKTRACE_ON_KRETPROBE
 	select ARCH_ENABLE_HUGEPAGE_MIGRATION if X86_64 && HUGETLB_PAGE && MIGRATION
 	select ARCH_ENABLE_MEMORY_HOTPLUG if X86_64
-	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if (PGTABLE_LEVELS > 2) && (X86_64 || X86_PAE)
 	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
 	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI

mm/Kconfig

@@ -465,9 +465,6 @@ config HAVE_BOOTMEM_INFO_NODE
 config ARCH_ENABLE_MEMORY_HOTPLUG
 	bool
 
-config ARCH_ENABLE_MEMORY_HOTREMOVE
-	bool
-
 # eventually, we can have this option just 'select SPARSEMEM'
 menuconfig MEMORY_HOTPLUG
 	bool "Memory hotplug"
@@ -540,8 +537,8 @@ endchoice
 config MEMORY_HOTREMOVE
 	bool "Allow for memory hot remove"
 	select HAVE_BOOTMEM_INFO_NODE if (X86_64 || PPC64)
-	depends on MEMORY_HOTPLUG && ARCH_ENABLE_MEMORY_HOTREMOVE
+	depends on MEMORY_HOTPLUG
-	depends on MIGRATION
+	select MIGRATION
 
 config MHP_MEMMAP_ON_MEMORY
 	def_bool y
@@ -636,7 +633,7 @@ config PAGE_REPORTING
 config MIGRATION
 	bool "Page migration"
 	default y
-	depends on (NUMA || ARCH_ENABLE_MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
+	depends on (NUMA || MEMORY_HOTREMOVE || COMPACTION || CMA) && MMU
 	help
 	  Allows the migration of the physical location of pages of processes
 	  while the virtual addresses are not changed. This is useful in