+ drivers-base-mm-move-arch_numac-to-mm.patch added to mm-new branch

+ drivers-base-mm-move-arch_numac-to-mm.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: drivers/base, mm: move arch_numa.c to mm/
has been added to the -mm mm-new branch.  Its filename is
     drivers-base-mm-move-arch_numac-to-mm.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/drivers-base-mm-move-arch_numac-to-mm.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
Subject: drivers/base, mm: move arch_numa.c to mm/
Date: Thu, 06 Aug 2026 09:58:38 +0300

arch_numa.c implements boot time discovery and initialization of NUMA
topology on architectures that select GENERIC_ARCH_NUMA (currently arm64
and riscv).

Since this is step in the initialization of the memory management
subsystem, it's logical to have arch_numa.c in mm/ alongside numa.c,
numa_memblks.c and numa_emulation.c.

Move arch_numa.c to mm/ and add its F: entry to "MEMBLOCK AND MEMORY
MANAGEMENT INITIALIZATION" in MAINTAINERS.

Link: https://lore.kernel.org/20260806-arch-numa-v1-1-968ec128121e@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 MAINTAINERS              |    1 
 drivers/base/Kconfig     |    7 
 drivers/base/Makefile    |    1 
 drivers/base/arch_numa.c |  375 -------------------------------------
 mm/Kconfig               |    7 
 mm/Makefile              |    1 
 mm/arch_numa.c           |  375 +++++++++++++++++++++++++++++++++++++
 7 files changed, 384 insertions(+), 383 deletions(-)

diff --git a/drivers/base/arch_numa.c a/drivers/base/arch_numa.c
deleted file mode 100644
--- a/drivers/base/arch_numa.c
+++ /dev/null
@@ -1,375 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * NUMA support, based on the x86 implementation.
- *
- * Copyright (C) 2015 Cavium Inc.
- * Author: Ganapatrao Kulkarni <gkulkarni@cavium.com>
- */
-
-#define pr_fmt(fmt) "NUMA: " fmt
-
-#include <linux/acpi.h>
-#include <linux/memblock.h>
-#include <linux/module.h>
-#include <linux/of.h>
-#include <linux/numa_memblks.h>
-
-#include <asm/sections.h>
-
-static int cpu_to_node_map[NR_CPUS] = { [0 ... NR_CPUS-1] = NUMA_NO_NODE };
-
-bool numa_off;
-
-static __init int numa_parse_early_param(char *opt)
-{
-	if (!opt)
-		return -EINVAL;
-	if (str_has_prefix(opt, "off"))
-		numa_off = true;
-	if (!strncmp(opt, "fake=", 5))
-		return numa_emu_cmdline(opt + 5);
-
-	return 0;
-}
-early_param("numa", numa_parse_early_param);
-
-cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
-EXPORT_SYMBOL(node_to_cpumask_map);
-
-#ifdef CONFIG_DEBUG_PER_CPU_MAPS
-
-/*
- * Returns a pointer to the bitmask of CPUs on Node 'node'.
- */
-const struct cpumask *cpumask_of_node(int node)
-{
-
-	if (node == NUMA_NO_NODE)
-		return cpu_all_mask;
-
-	if (WARN_ON(node < 0 || node >= nr_node_ids))
-		return cpu_none_mask;
-
-	if (WARN_ON(node_to_cpumask_map[node] == NULL))
-		return cpu_online_mask;
-
-	return node_to_cpumask_map[node];
-}
-EXPORT_SYMBOL(cpumask_of_node);
-
-#endif
-
-#ifndef CONFIG_NUMA_EMU
-static void numa_update_cpu(unsigned int cpu, bool remove)
-{
-	int nid = cpu_to_node(cpu);
-
-	if (nid == NUMA_NO_NODE)
-		return;
-
-	if (remove)
-		cpumask_clear_cpu(cpu, node_to_cpumask_map[nid]);
-	else
-		cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
-}
-
-void numa_add_cpu(unsigned int cpu)
-{
-	numa_update_cpu(cpu, false);
-}
-
-void numa_remove_cpu(unsigned int cpu)
-{
-	numa_update_cpu(cpu, true);
-}
-#endif
-
-void numa_clear_node(unsigned int cpu)
-{
-	numa_remove_cpu(cpu);
-	set_cpu_numa_node(cpu, NUMA_NO_NODE);
-}
-
-/*
- * Allocate node_to_cpumask_map based on number of available nodes
- * Requires node_possible_map to be valid.
- *
- * Note: cpumask_of_node() is not valid until after this is done.
- * (Use CONFIG_DEBUG_PER_CPU_MAPS to check this.)
- */
-static void __init setup_node_to_cpumask_map(void)
-{
-	int node;
-
-	/* setup nr_node_ids if not done yet */
-	if (nr_node_ids == MAX_NUMNODES)
-		setup_nr_node_ids();
-
-	/* allocate and clear the mapping */
-	for (node = 0; node < nr_node_ids; node++) {
-		alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);
-		cpumask_clear(node_to_cpumask_map[node]);
-	}
-
-	/* cpumask_of_node() will now work */
-	pr_debug("Node to cpumask map for %u nodes\n", nr_node_ids);
-}
-
-/*
- * Set the cpu to node and mem mapping
- */
-void numa_store_cpu_info(unsigned int cpu)
-{
-	set_cpu_numa_node(cpu, cpu_to_node_map[cpu]);
-}
-
-void __init early_map_cpu_to_node(unsigned int cpu, int nid)
-{
-	/* fallback to node 0 */
-	if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
-		nid = 0;
-
-	cpu_to_node_map[cpu] = nid;
-
-	/*
-	 * We should set the numa node of cpu0 as soon as possible, because it
-	 * has already been set up online before. cpu_to_node(0) will soon be
-	 * called.
-	 */
-	if (!cpu)
-		set_cpu_numa_node(cpu, nid);
-}
-
-#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
-unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
-EXPORT_SYMBOL(__per_cpu_offset);
-
-int early_cpu_to_node(int cpu)
-{
-	return cpu_to_node_map[cpu];
-}
-
-static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
-{
-	return node_distance(early_cpu_to_node(from), early_cpu_to_node(to));
-}
-
-void __init setup_per_cpu_areas(void)
-{
-	unsigned long delta;
-	unsigned int cpu;
-	int rc = -EINVAL;
-
-	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
-		/*
-		 * Always reserve area for module percpu variables.  That's
-		 * what the legacy allocator did.
-		 */
-		rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
-					    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE,
-					    pcpu_cpu_distance,
-					    early_cpu_to_node);
-#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
-		if (rc < 0)
-			pr_warn("PERCPU: %s allocator failed (%d), falling back to page size\n",
-				   pcpu_fc_names[pcpu_chosen_fc], rc);
-#endif
-	}
-
-#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
-	if (rc < 0)
-		rc = pcpu_page_first_chunk(PERCPU_MODULE_RESERVE, early_cpu_to_node);
-#endif
-	if (rc < 0)
-		panic("Failed to initialize percpu areas (err=%d).", rc);
-
-	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
-	for_each_possible_cpu(cpu)
-		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
-}
-#endif
-
-/*
- * Initialize NODE_DATA for a node on the local memory
- */
-static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
-{
-	if (start_pfn >= end_pfn)
-		pr_info("Initmem setup node %d [<memory-less node>]\n", nid);
-
-	alloc_node_data(nid);
-
-	NODE_DATA(nid)->node_id = nid;
-	NODE_DATA(nid)->node_start_pfn = start_pfn;
-	NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;
-}
-
-static int __init numa_register_nodes(void)
-{
-	int nid;
-
-	/* Check the validity of the memblock/node mapping */
-	if (!memblock_validate_numa_coverage(0))
-		return -EINVAL;
-
-	/* Finally register nodes. */
-	for_each_node_mask(nid, numa_nodes_parsed) {
-		unsigned long start_pfn, end_pfn;
-
-		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
-		setup_node_data(nid, start_pfn, end_pfn);
-		node_set_online(nid);
-	}
-
-	/* Setup online nodes to actual nodes*/
-	node_possible_map = numa_nodes_parsed;
-
-	return 0;
-}
-
-static int __init numa_init(int (*init_func)(void))
-{
-	int ret;
-
-	ret = numa_memblks_init(init_func, /* memblock_force_top_down */ false);
-	if (ret < 0)
-		goto out_free_distance;
-
-	if (nodes_empty(numa_nodes_parsed)) {
-		pr_info("No NUMA configuration found\n");
-		ret = -EINVAL;
-		goto out_free_distance;
-	}
-
-	ret = numa_register_nodes();
-	if (ret < 0)
-		goto out_free_distance;
-
-	setup_node_to_cpumask_map();
-
-	return 0;
-out_free_distance:
-	numa_reset_distance();
-	return ret;
-}
-
-/**
- * dummy_numa_init() - Fallback dummy NUMA init
- *
- * Used if there's no underlying NUMA architecture, NUMA initialization
- * fails, or NUMA is disabled on the command line.
- *
- * Must online at least one node (node 0) and add memory blocks that cover all
- * allowed memory. It is unlikely that this function fails.
- *
- * Return: 0 on success, -errno on failure.
- */
-static int __init dummy_numa_init(void)
-{
-	phys_addr_t start = memblock_start_of_DRAM();
-	phys_addr_t end = memblock_end_of_DRAM() - 1;
-	int ret;
-
-	if (numa_off)
-		pr_info("NUMA disabled\n"); /* Forced off on command line. */
-	pr_info("Faking a node at [mem %pap-%pap]\n", &start, &end);
-
-	ret = numa_add_memblk(0, start, end + 1);
-	if (ret) {
-		pr_err("NUMA init failed\n");
-		return ret;
-	}
-	node_set(0, numa_nodes_parsed);
-
-	numa_off = true;
-	return 0;
-}
-
-#ifdef CONFIG_ACPI_NUMA
-static int __init arch_acpi_numa_init(void)
-{
-	int ret;
-
-	ret = acpi_numa_init();
-	if (ret) {
-		pr_debug("Failed to initialise from firmware\n");
-		return ret;
-	}
-
-	return srat_disabled() ? -EINVAL : 0;
-}
-#else
-static int __init arch_acpi_numa_init(void)
-{
-	return -EOPNOTSUPP;
-}
-#endif
-
-/**
- * arch_numa_init() - Initialize NUMA
- *
- * Try each configured NUMA initialization method until one succeeds. The
- * last fallback is dummy single node config encompassing whole memory.
- */
-void __init arch_numa_init(void)
-{
-	if (!numa_off) {
-		if (!acpi_disabled && !numa_init(arch_acpi_numa_init))
-			return;
-		if (acpi_disabled && !numa_init(of_numa_init))
-			return;
-	}
-
-	numa_init(dummy_numa_init);
-}
-
-#ifdef CONFIG_NUMA_EMU
-void __init numa_emu_update_cpu_to_node(int *emu_nid_to_phys,
-					unsigned int nr_emu_nids)
-{
-	int i, j;
-
-	/*
-	 * Transform cpu_to_node_map table to use emulated nids by
-	 * reverse-mapping phys_nid.  The maps should always exist but fall
-	 * back to zero just in case.
-	 */
-	for (i = 0; i < ARRAY_SIZE(cpu_to_node_map); i++) {
-		if (cpu_to_node_map[i] == NUMA_NO_NODE)
-			continue;
-		for (j = 0; j < nr_emu_nids; j++)
-			if (cpu_to_node_map[i] == emu_nid_to_phys[j])
-				break;
-		cpu_to_node_map[i] = j < nr_emu_nids ? j : 0;
-	}
-}
-
-u64 __init numa_emu_dma_end(void)
-{
-	return memblock_start_of_DRAM() + SZ_4G;
-}
-
-void debug_cpumask_set_cpu(unsigned int cpu, int node, bool enable)
-{
-	struct cpumask *mask;
-
-	if (node == NUMA_NO_NODE)
-		return;
-
-	mask = node_to_cpumask_map[node];
-	if (!cpumask_available(mask)) {
-		pr_err("node_to_cpumask_map[%i] NULL\n", node);
-		dump_stack();
-		return;
-	}
-
-	if (enable)
-		cpumask_set_cpu(cpu, mask);
-	else
-		cpumask_clear_cpu(cpu, mask);
-
-	pr_debug("%s cpu %d node %d: mask now %*pbl\n",
-		 enable ? "numa_add_cpu" : "numa_remove_cpu",
-		 cpu, node, cpumask_pr_args(mask));
-}
-#endif /* CONFIG_NUMA_EMU */
--- a/drivers/base/Kconfig~drivers-base-mm-move-arch_numac-to-mm
+++ a/drivers/base/Kconfig
@@ -239,13 +239,6 @@ config GENERIC_ARCH_TOPOLOGY
 	  appropriate scaling, sysfs interface for reading capacity values at
 	  runtime.
 
-config GENERIC_ARCH_NUMA
-	bool
-	select NUMA_MEMBLKS
-	help
-	  Enable support for generic NUMA implementation. Currently, RISC-V
-	  and ARM64 use it.
-
 config FW_DEVLINK_SYNC_STATE_TIMEOUT
 	bool "sync_state() behavior defaults to timeout instead of strict"
 	help
--- a/drivers/base/Makefile~drivers-base-mm-move-arch_numac-to-mm
+++ a/drivers/base/Makefile
@@ -25,7 +25,6 @@ obj-$(CONFIG_PINCTRL) += pinctrl.o
 obj-$(CONFIG_DEV_COREDUMP) += devcoredump.o
 obj-$(CONFIG_GENERIC_MSI_IRQ) += platform-msi.o
 obj-$(CONFIG_GENERIC_ARCH_TOPOLOGY) += arch_topology.o
-obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o
 obj-$(CONFIG_ACPI) += physical_location.o
 
 obj-y			+= test/
--- a/MAINTAINERS~drivers-base-mm-move-arch_numac-to-mm
+++ a/MAINTAINERS
@@ -16880,6 +16880,7 @@ T:	git git://git.kernel.org/pub/scm/linu
 F:	Documentation/core-api/boot-time-mm.rst
 F:	include/linux/kho/abi/memblock.h
 F:	include/linux/memblock.h
+F:	mm/arch_numa.c
 F:	mm/memblock.c
 F:	mm/memtest.c
 F:	mm/mm_init.c
diff --git a/mm/arch_numa.c a/mm/arch_numa.c
new file mode 100664
--- /dev/null
+++ a/mm/arch_numa.c
@@ -0,0 +1,375 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * NUMA support, based on the x86 implementation.
+ *
+ * Copyright (C) 2015 Cavium Inc.
+ * Author: Ganapatrao Kulkarni <gkulkarni@cavium.com>
+ */
+
+#define pr_fmt(fmt) "NUMA: " fmt
+
+#include <linux/acpi.h>
+#include <linux/memblock.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/numa_memblks.h>
+
+#include <asm/sections.h>
+
+static int cpu_to_node_map[NR_CPUS] = { [0 ... NR_CPUS-1] = NUMA_NO_NODE };
+
+bool numa_off;
+
+static __init int numa_parse_early_param(char *opt)
+{
+	if (!opt)
+		return -EINVAL;
+	if (str_has_prefix(opt, "off"))
+		numa_off = true;
+	if (!strncmp(opt, "fake=", 5))
+		return numa_emu_cmdline(opt + 5);
+
+	return 0;
+}
+early_param("numa", numa_parse_early_param);
+
+cpumask_var_t node_to_cpumask_map[MAX_NUMNODES];
+EXPORT_SYMBOL(node_to_cpumask_map);
+
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+
+/*
+ * Returns a pointer to the bitmask of CPUs on Node 'node'.
+ */
+const struct cpumask *cpumask_of_node(int node)
+{
+
+	if (node == NUMA_NO_NODE)
+		return cpu_all_mask;
+
+	if (WARN_ON(node < 0 || node >= nr_node_ids))
+		return cpu_none_mask;
+
+	if (WARN_ON(node_to_cpumask_map[node] == NULL))
+		return cpu_online_mask;
+
+	return node_to_cpumask_map[node];
+}
+EXPORT_SYMBOL(cpumask_of_node);
+
+#endif
+
+#ifndef CONFIG_NUMA_EMU
+static void numa_update_cpu(unsigned int cpu, bool remove)
+{
+	int nid = cpu_to_node(cpu);
+
+	if (nid == NUMA_NO_NODE)
+		return;
+
+	if (remove)
+		cpumask_clear_cpu(cpu, node_to_cpumask_map[nid]);
+	else
+		cpumask_set_cpu(cpu, node_to_cpumask_map[nid]);
+}
+
+void numa_add_cpu(unsigned int cpu)
+{
+	numa_update_cpu(cpu, false);
+}
+
+void numa_remove_cpu(unsigned int cpu)
+{
+	numa_update_cpu(cpu, true);
+}
+#endif
+
+void numa_clear_node(unsigned int cpu)
+{
+	numa_remove_cpu(cpu);
+	set_cpu_numa_node(cpu, NUMA_NO_NODE);
+}
+
+/*
+ * Allocate node_to_cpumask_map based on number of available nodes
+ * Requires node_possible_map to be valid.
+ *
+ * Note: cpumask_of_node() is not valid until after this is done.
+ * (Use CONFIG_DEBUG_PER_CPU_MAPS to check this.)
+ */
+static void __init setup_node_to_cpumask_map(void)
+{
+	int node;
+
+	/* setup nr_node_ids if not done yet */
+	if (nr_node_ids == MAX_NUMNODES)
+		setup_nr_node_ids();
+
+	/* allocate and clear the mapping */
+	for (node = 0; node < nr_node_ids; node++) {
+		alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]);
+		cpumask_clear(node_to_cpumask_map[node]);
+	}
+
+	/* cpumask_of_node() will now work */
+	pr_debug("Node to cpumask map for %u nodes\n", nr_node_ids);
+}
+
+/*
+ * Set the cpu to node and mem mapping
+ */
+void numa_store_cpu_info(unsigned int cpu)
+{
+	set_cpu_numa_node(cpu, cpu_to_node_map[cpu]);
+}
+
+void __init early_map_cpu_to_node(unsigned int cpu, int nid)
+{
+	/* fallback to node 0 */
+	if (nid < 0 || nid >= MAX_NUMNODES || numa_off)
+		nid = 0;
+
+	cpu_to_node_map[cpu] = nid;
+
+	/*
+	 * We should set the numa node of cpu0 as soon as possible, because it
+	 * has already been set up online before. cpu_to_node(0) will soon be
+	 * called.
+	 */
+	if (!cpu)
+		set_cpu_numa_node(cpu, nid);
+}
+
+#ifdef CONFIG_HAVE_SETUP_PER_CPU_AREA
+unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL(__per_cpu_offset);
+
+int early_cpu_to_node(int cpu)
+{
+	return cpu_to_node_map[cpu];
+}
+
+static int __init pcpu_cpu_distance(unsigned int from, unsigned int to)
+{
+	return node_distance(early_cpu_to_node(from), early_cpu_to_node(to));
+}
+
+void __init setup_per_cpu_areas(void)
+{
+	unsigned long delta;
+	unsigned int cpu;
+	int rc = -EINVAL;
+
+	if (pcpu_chosen_fc != PCPU_FC_PAGE) {
+		/*
+		 * Always reserve area for module percpu variables.  That's
+		 * what the legacy allocator did.
+		 */
+		rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
+					    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE,
+					    pcpu_cpu_distance,
+					    early_cpu_to_node);
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+		if (rc < 0)
+			pr_warn("PERCPU: %s allocator failed (%d), falling back to page size\n",
+				   pcpu_fc_names[pcpu_chosen_fc], rc);
+#endif
+	}
+
+#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
+	if (rc < 0)
+		rc = pcpu_page_first_chunk(PERCPU_MODULE_RESERVE, early_cpu_to_node);
+#endif
+	if (rc < 0)
+		panic("Failed to initialize percpu areas (err=%d).", rc);
+
+	delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
+	for_each_possible_cpu(cpu)
+		__per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
+}
+#endif
+
+/*
+ * Initialize NODE_DATA for a node on the local memory
+ */
+static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
+{
+	if (start_pfn >= end_pfn)
+		pr_info("Initmem setup node %d [<memory-less node>]\n", nid);
+
+	alloc_node_data(nid);
+
+	NODE_DATA(nid)->node_id = nid;
+	NODE_DATA(nid)->node_start_pfn = start_pfn;
+	NODE_DATA(nid)->node_spanned_pages = end_pfn - start_pfn;
+}
+
+static int __init numa_register_nodes(void)
+{
+	int nid;
+
+	/* Check the validity of the memblock/node mapping */
+	if (!memblock_validate_numa_coverage(0))
+		return -EINVAL;
+
+	/* Finally register nodes. */
+	for_each_node_mask(nid, numa_nodes_parsed) {
+		unsigned long start_pfn, end_pfn;
+
+		get_pfn_range_for_nid(nid, &start_pfn, &end_pfn);
+		setup_node_data(nid, start_pfn, end_pfn);
+		node_set_online(nid);
+	}
+
+	/* Setup online nodes to actual nodes*/
+	node_possible_map = numa_nodes_parsed;
+
+	return 0;
+}
+
+static int __init numa_init(int (*init_func)(void))
+{
+	int ret;
+
+	ret = numa_memblks_init(init_func, /* memblock_force_top_down */ false);
+	if (ret < 0)
+		goto out_free_distance;
+
+	if (nodes_empty(numa_nodes_parsed)) {
+		pr_info("No NUMA configuration found\n");
+		ret = -EINVAL;
+		goto out_free_distance;
+	}
+
+	ret = numa_register_nodes();
+	if (ret < 0)
+		goto out_free_distance;
+
+	setup_node_to_cpumask_map();
+
+	return 0;
+out_free_distance:
+	numa_reset_distance();
+	return ret;
+}
+
+/**
+ * dummy_numa_init() - Fallback dummy NUMA init
+ *
+ * Used if there's no underlying NUMA architecture, NUMA initialization
+ * fails, or NUMA is disabled on the command line.
+ *
+ * Must online at least one node (node 0) and add memory blocks that cover all
+ * allowed memory. It is unlikely that this function fails.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+static int __init dummy_numa_init(void)
+{
+	phys_addr_t start = memblock_start_of_DRAM();
+	phys_addr_t end = memblock_end_of_DRAM() - 1;
+	int ret;
+
+	if (numa_off)
+		pr_info("NUMA disabled\n"); /* Forced off on command line. */
+	pr_info("Faking a node at [mem %pap-%pap]\n", &start, &end);
+
+	ret = numa_add_memblk(0, start, end + 1);
+	if (ret) {
+		pr_err("NUMA init failed\n");
+		return ret;
+	}
+	node_set(0, numa_nodes_parsed);
+
+	numa_off = true;
+	return 0;
+}
+
+#ifdef CONFIG_ACPI_NUMA
+static int __init arch_acpi_numa_init(void)
+{
+	int ret;
+
+	ret = acpi_numa_init();
+	if (ret) {
+		pr_debug("Failed to initialise from firmware\n");
+		return ret;
+	}
+
+	return srat_disabled() ? -EINVAL : 0;
+}
+#else
+static int __init arch_acpi_numa_init(void)
+{
+	return -EOPNOTSUPP;
+}
+#endif
+
+/**
+ * arch_numa_init() - Initialize NUMA
+ *
+ * Try each configured NUMA initialization method until one succeeds. The
+ * last fallback is dummy single node config encompassing whole memory.
+ */
+void __init arch_numa_init(void)
+{
+	if (!numa_off) {
+		if (!acpi_disabled && !numa_init(arch_acpi_numa_init))
+			return;
+		if (acpi_disabled && !numa_init(of_numa_init))
+			return;
+	}
+
+	numa_init(dummy_numa_init);
+}
+
+#ifdef CONFIG_NUMA_EMU
+void __init numa_emu_update_cpu_to_node(int *emu_nid_to_phys,
+					unsigned int nr_emu_nids)
+{
+	int i, j;
+
+	/*
+	 * Transform cpu_to_node_map table to use emulated nids by
+	 * reverse-mapping phys_nid.  The maps should always exist but fall
+	 * back to zero just in case.
+	 */
+	for (i = 0; i < ARRAY_SIZE(cpu_to_node_map); i++) {
+		if (cpu_to_node_map[i] == NUMA_NO_NODE)
+			continue;
+		for (j = 0; j < nr_emu_nids; j++)
+			if (cpu_to_node_map[i] == emu_nid_to_phys[j])
+				break;
+		cpu_to_node_map[i] = j < nr_emu_nids ? j : 0;
+	}
+}
+
+u64 __init numa_emu_dma_end(void)
+{
+	return memblock_start_of_DRAM() + SZ_4G;
+}
+
+void debug_cpumask_set_cpu(unsigned int cpu, int node, bool enable)
+{
+	struct cpumask *mask;
+
+	if (node == NUMA_NO_NODE)
+		return;
+
+	mask = node_to_cpumask_map[node];
+	if (!cpumask_available(mask)) {
+		pr_err("node_to_cpumask_map[%i] NULL\n", node);
+		dump_stack();
+		return;
+	}
+
+	if (enable)
+		cpumask_set_cpu(cpu, mask);
+	else
+		cpumask_clear_cpu(cpu, mask);
+
+	pr_debug("%s cpu %d node %d: mask now %*pbl\n",
+		 enable ? "numa_add_cpu" : "numa_remove_cpu",
+		 cpu, node, cpumask_pr_args(mask));
+}
+#endif /* CONFIG_NUMA_EMU */
--- a/mm/Kconfig~drivers-base-mm-move-arch_numac-to-mm
+++ a/mm/Kconfig
@@ -1463,6 +1463,13 @@ config NUMA_EMU
 	  into virtual nodes when booted with "numa=fake=N", where N is the
 	  number of nodes. This is only useful for debugging.
 
+config GENERIC_ARCH_NUMA
+	bool
+	select NUMA_MEMBLKS
+	help
+	  Enable support for generic NUMA implementation. Currently, RISC-V
+	  and ARM64 use it.
+
 config ARCH_HAS_USER_SHADOW_STACK
 	bool
 	help
--- a/mm/Makefile~drivers-base-mm-move-arch_numac-to-mm
+++ a/mm/Makefile
@@ -122,6 +122,7 @@ obj-$(CONFIG_CMA)	+= cma.o
 obj-$(CONFIG_NUMA) += numa.o
 obj-$(CONFIG_NUMA_MEMBLKS) += numa_memblks.o
 obj-$(CONFIG_NUMA_EMU) += numa_emulation.o
+obj-$(CONFIG_GENERIC_ARCH_NUMA) += arch_numa.o
 obj-$(CONFIG_BALLOON) += balloon.o
 obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
 obj-$(CONFIG_PAGE_TABLE_CHECK) += page_table_check.o
_

Patches currently in -mm which might be from rppt@kernel.org are

sh-remove-config_numa-and-realted-configuration-options.patch
sh-mm-remove-numac.patch
sh-mm-drop-allocate_pgdat.patch
sh-remove-setup_bootmem_node-and-plat_mem_setup.patch
sh-drop-dead-code-guarded-by-ifdef-config_numa.patch
sh-drop-include-asm-mmzoneh.patch
init-kconfig-drop-arch_want_numa_variable_locality.patch
sh-init-remove-call-the-memblock_set_node.patch
sh-remove-sparsemem-related-entries-from-kconfig.patch
sh-drop-include-asm-sparsememh.patch
drivers-base-mm-move-arch_numac-to-mm.patch