Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2282 insertions, 0 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
new file mode 100644
index 000000000..3b9d3a4b4
--- /dev/null
+++ b/mm/memory_hotplug.c
@@ -0,0 +1,2282 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/mm/memory_hotplug.c
+ *
+ *  Copyright (C)
+ */
+
+#include <linux/stddef.h>
+#include <linux/mm.h>
+#include <linux/sched/signal.h>
+#include <linux/swap.h>
+#include <linux/interrupt.h>
+#include <linux/pagemap.h>
+#include <linux/compiler.h>
+#include <linux/export.h>
+#include <linux/pagevec.h>
+#include <linux/writeback.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
+#include <linux/cpu.h>
+#include <linux/memory.h>
+#include <linux/memremap.h>
+#include <linux/memory_hotplug.h>
+#include <linux/vmalloc.h>
+#include <linux/ioport.h>
+#include <linux/delay.h>
+#include <linux/migrate.h>
+#include <linux/page-isolation.h>
+#include <linux/pfn.h>
+#include <linux/suspend.h>
+#include <linux/mm_inline.h>
+#include <linux/firmware-map.h>
+#include <linux/stop_machine.h>
+#include <linux/hugetlb.h>
+#include <linux/memblock.h>
+#include <linux/compaction.h>
+#include <linux/rmap.h>
+#include <linux/module.h>
+
+#include <asm/tlbflush.h>
+
+#include "internal.h"
+#include "shuffle.h"
+
+#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY
+/*
+ * memory_hotplug.memmap_on_memory parameter
+ */
+static bool memmap_on_memory __ro_after_init;
+module_param(memmap_on_memory, bool, 0444);
+MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug");
+
+static inline bool mhp_memmap_on_memory(void)
+{
+	return memmap_on_memory;
+}
+#else
+static inline bool mhp_memmap_on_memory(void)
+{
+	return false;
+}
+#endif
+
+enum {
+	ONLINE_POLICY_CONTIG_ZONES = 0,
+	ONLINE_POLICY_AUTO_MOVABLE,
+};
+
+static const char * const online_policy_to_str[] = {
+	[ONLINE_POLICY_CONTIG_ZONES] = "contig-zones",
+	[ONLINE_POLICY_AUTO_MOVABLE] = "auto-movable",
+};
+
+static int set_online_policy(const char *val, const struct kernel_param *kp)
+{
+	int ret = sysfs_match_string(online_policy_to_str, val);
+
+	if (ret < 0)
+		return ret;
+	*((int *)kp->arg) = ret;
+	return 0;
+}
+
+static int get_online_policy(char *buffer, const struct kernel_param *kp)
+{
+	return sprintf(buffer, "%s\n", online_policy_to_str[*((int *)kp->arg)]);
+}
+
+/*
+ * memory_hotplug.online_policy: configure online behavior when onlining without
+ * specifying a zone (MMOP_ONLINE)
+ *
+ * "contig-zones": keep zone contiguous
+ * "auto-movable": online memory to ZONE_MOVABLE if the configuration
+ *                 (auto_movable_ratio, auto_movable_numa_aware) allows for it
+ */
+static int online_policy __read_mostly = ONLINE_POLICY_CONTIG_ZONES;
+static const struct kernel_param_ops online_policy_ops = {
+	.set = set_online_policy,
+	.get = get_online_policy,
+};
+module_param_cb(online_policy, &online_policy_ops, &online_policy, 0644);
+MODULE_PARM_DESC(online_policy,
+		"Set the online policy (\"contig-zones\", \"auto-movable\") "
+		"Default: \"contig-zones\"");
+
+/*
+ * memory_hotplug.auto_movable_ratio: specify maximum MOVABLE:KERNEL ratio
+ *
+ * The ratio represent an upper limit and the kernel might decide to not
+ * online some memory to ZONE_MOVABLE -- e.g., because hotplugged KERNEL memory
+ * doesn't allow for more MOVABLE memory.
+ */
+static unsigned int auto_movable_ratio __read_mostly = 301;
+module_param(auto_movable_ratio, uint, 0644);
+MODULE_PARM_DESC(auto_movable_ratio,
+		"Set the maximum ratio of MOVABLE:KERNEL memory in the system "
+		"in percent for \"auto-movable\" online policy. Default: 301");
+
+/*
+ * memory_hotplug.auto_movable_numa_aware: consider numa node stats
+ */
+#ifdef CONFIG_NUMA
+static bool auto_movable_numa_aware __read_mostly = true;
+module_param(auto_movable_numa_aware, bool, 0644);
+MODULE_PARM_DESC(auto_movable_numa_aware,
+		"Consider numa node stats in addition to global stats in "
+		"\"auto-movable\" online policy. Default: true");
+#endif /* CONFIG_NUMA */
+
+/*
+ * online_page_callback contains pointer to current page onlining function.
+ * Initially it is generic_online_page(). If it is required it could be
+ * changed by calling set_online_page_callback() for callback registration
+ * and restore_online_page_callback() for generic callback restore.
+ */
+
+static online_page_callback_t online_page_callback = generic_online_page;
+static DEFINE_MUTEX(online_page_callback_lock);
+
+DEFINE_STATIC_PERCPU_RWSEM(mem_hotplug_lock);
+
+void get_online_mems(void)
+{
+	percpu_down_read(&mem_hotplug_lock);
+}
+
+void put_online_mems(void)
+{
+	percpu_up_read(&mem_hotplug_lock);
+}
+
+bool movable_node_enabled = false;
+
+#ifndef CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE
+int mhp_default_online_type = MMOP_OFFLINE;
+#else
+int mhp_default_online_type = MMOP_ONLINE;
+#endif
+
+static int __init setup_memhp_default_state(char *str)
+{
+	const int online_type = mhp_online_type_from_str(str);
+
+	if (online_type >= 0)
+		mhp_default_online_type = online_type;
+
+	return 1;
+}
+__setup("memhp_default_state=", setup_memhp_default_state);
+
+void mem_hotplug_begin(void)
+{
+	cpus_read_lock();
+	percpu_down_write(&mem_hotplug_lock);
+}
+
+void mem_hotplug_done(void)
+{
+	percpu_up_write(&mem_hotplug_lock);
+	cpus_read_unlock();
+}
+
+u64 max_mem_size = U64_MAX;
+
+/* add this memory to iomem resource */
+static struct resource *register_memory_resource(u64 start, u64 size,
+						 const char *resource_name)
+{
+	struct resource *res;
+	unsigned long flags =  IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+
+	if (strcmp(resource_name, "System RAM"))
+		flags |= IORESOURCE_SYSRAM_DRIVER_MANAGED;
+
+	if (!mhp_range_allowed(start, size, true))
+		return ERR_PTR(-E2BIG);
+
+	/*
+	 * Make sure value parsed from 'mem=' only restricts memory adding
+	 * while booting, so that memory hotplug won't be impacted. Please
+	 * refer to document of 'mem=' in kernel-parameters.txt for more
+	 * details.
+	 */
+	if (start + size > max_mem_size && system_state < SYSTEM_RUNNING)
+		return ERR_PTR(-E2BIG);
+
+	/*
+	 * Request ownership of the new memory range.  This might be
+	 * a child of an existing resource that was present but
+	 * not marked as busy.
+	 */
+	res = __request_region(&iomem_resource, start, size,
+			       resource_name, flags);
+
+	if (!res) {
+		pr_debug("Unable to reserve System RAM region: %016llx->%016llx\n",
+				start, start + size);
+		return ERR_PTR(-EEXIST);
+	}
+	return res;
+}
+
+static void release_memory_resource(struct resource *res)
+{
+	if (!res)
+		return;
+	release_resource(res);
+	kfree(res);
+}
+
+static int check_pfn_span(unsigned long pfn, unsigned long nr_pages)
+{
+	/*
+	 * Disallow all operations smaller than a sub-section and only
+	 * allow operations smaller than a section for
+	 * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range()
+	 * enforces a larger memory_block_size_bytes() granularity for
+	 * memory that will be marked online, so this check should only
+	 * fire for direct arch_{add,remove}_memory() users outside of
+	 * add_memory_resource().
+	 */
+	unsigned long min_align;
+
+	if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP))
+		min_align = PAGES_PER_SUBSECTION;
+	else
+		min_align = PAGES_PER_SECTION;
+	if (!IS_ALIGNED(pfn | nr_pages, min_align))
+		return -EINVAL;
+	return 0;
+}
+
+/*
+ * Return page for the valid pfn only if the page is online. All pfn
+ * walkers which rely on the fully initialized page->flags and others
+ * should use this rather than pfn_valid && pfn_to_page
+ */
+struct page *pfn_to_online_page(unsigned long pfn)
+{
+	unsigned long nr = pfn_to_section_nr(pfn);
+	struct dev_pagemap *pgmap;
+	struct mem_section *ms;
+
+	if (nr >= NR_MEM_SECTIONS)
+		return NULL;
+
+	ms = __nr_to_section(nr);
+	if (!online_section(ms))
+		return NULL;
+
+	/*
+	 * Save some code text when online_section() +
+	 * pfn_section_valid() are sufficient.
+	 */
+	if (IS_ENABLED(CONFIG_HAVE_ARCH_PFN_VALID) && !pfn_valid(pfn))
+		return NULL;
+
+	if (!pfn_section_valid(ms, pfn))
+		return NULL;
+
+	if (!online_device_section(ms))
+		return pfn_to_page(pfn);
+
+	/*
+	 * Slowpath: when ZONE_DEVICE collides with
+	 * ZONE_{NORMAL,MOVABLE} within the same section some pfns in
+	 * the section may be 'offline' but 'valid'. Only
+	 * get_dev_pagemap() can determine sub-section online status.
+	 */
+	pgmap = get_dev_pagemap(pfn, NULL);
+	put_dev_pagemap(pgmap);
+
+	/* The presence of a pgmap indicates ZONE_DEVICE offline pfn */
+	if (pgmap)
+		return NULL;
+
+	return pfn_to_page(pfn);
+}
+EXPORT_SYMBOL_GPL(pfn_to_online_page);
+
+int __ref __add_pages(int nid, unsigned long pfn, unsigned long nr_pages,
+		struct mhp_params *params)
+{
+	const unsigned long end_pfn = pfn + nr_pages;
+	unsigned long cur_nr_pages;
+	int err;
+	struct vmem_altmap *altmap = params->altmap;
+
+	if (WARN_ON_ONCE(!pgprot_val(params->pgprot)))
+		return -EINVAL;
+
+	VM_BUG_ON(!mhp_range_allowed(PFN_PHYS(pfn), nr_pages * PAGE_SIZE, false));
+
+	if (altmap) {
+		/*
+		 * Validate altmap is within bounds of the total request
+		 */
+		if (altmap->base_pfn != pfn
+				|| vmem_altmap_offset(altmap) > nr_pages) {
+			pr_warn_once("memory add fail, invalid altmap\n");
+			return -EINVAL;
+		}
+		altmap->alloc = 0;
+	}
+
+	if (check_pfn_span(pfn, nr_pages)) {
+		WARN(1, "Misaligned %s start: %#lx end: #%lx\n", __func__, pfn, pfn + nr_pages - 1);
+		return -EINVAL;
+	}
+
+	for (; pfn < end_pfn; pfn += cur_nr_pages) {
+		/* Select all remaining pages up to the next section boundary */
+		cur_nr_pages = min(end_pfn - pfn,
+				   SECTION_ALIGN_UP(pfn + 1) - pfn);
+		err = sparse_add_section(nid, pfn, cur_nr_pages, altmap,
+					 params->pgmap);
+		if (err)
+			break;
+		cond_resched();
+	}
+	vmemmap_populate_print_last();
+	return err;
+}
+
+/* find the smallest valid pfn in the range [start_pfn, end_pfn) */
+static unsigned long find_smallest_section_pfn(int nid, struct zone *zone,
+				     unsigned long start_pfn,
+				     unsigned long end_pfn)
+{
+	for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SUBSECTION) {
+		if (unlikely(!pfn_to_online_page(start_pfn)))
+			continue;
+
+		if (unlikely(pfn_to_nid(start_pfn) != nid))
+			continue;
+
+		if (zone != page_zone(pfn_to_page(start_pfn)))
+			continue;
+
+		return start_pfn;
+	}
+
+	return 0;
+}
+
+/* find the biggest valid pfn in the range [start_pfn, end_pfn). */
+static unsigned long find_biggest_section_pfn(int nid, struct zone *zone,
+				    unsigned long start_pfn,
+				    unsigned long end_pfn)
+{
+	unsigned long pfn;
+
+	/* pfn is the end pfn of a memory section. */
+	pfn = end_pfn - 1;
+	for (; pfn >= start_pfn; pfn -= PAGES_PER_SUBSECTION) {
+		if (unlikely(!pfn_to_online_page(pfn)))
+			continue;
+
+		if (unlikely(pfn_to_nid(pfn) != nid))
+			continue;
+
+		if (zone != page_zone(pfn_to_page(pfn)))
+			continue;
+
+		return pfn;
+	}
+
+	return 0;
+}
+
+static void shrink_zone_span(struct zone *zone, unsigned long start_pfn,
+			     unsigned long end_pfn)
+{
+	unsigned long pfn;
+	int nid = zone_to_nid(zone);
+
+	if (zone->zone_start_pfn == start_pfn) {
+		/*
+		 * If the section is smallest section in the zone, it need
+		 * shrink zone->zone_start_pfn and zone->zone_spanned_pages.
+		 * In this case, we find second smallest valid mem_section
+		 * for shrinking zone.
+		 */
+		pfn = find_smallest_section_pfn(nid, zone, end_pfn,
+						zone_end_pfn(zone));
+		if (pfn) {
+			zone->spanned_pages = zone_end_pfn(zone) - pfn;
+			zone->zone_start_pfn = pfn;
+		} else {
+			zone->zone_start_pfn = 0;
+			zone->spanned_pages = 0;
+		}
+	} else if (zone_end_pfn(zone) == end_pfn) {
+		/*
+		 * If the section is biggest section in the zone, it need
+		 * shrink zone->spanned_pages.
+		 * In this case, we find second biggest valid mem_section for
+		 * shrinking zone.
+		 */
+		pfn = find_biggest_section_pfn(nid, zone, zone->zone_start_pfn,
+					       start_pfn);
+		if (pfn)
+			zone->spanned_pages = pfn - zone->zone_start_pfn + 1;
+		else {
+			zone->zone_start_pfn = 0;
+			zone->spanned_pages = 0;
+		}
+	}
+}
+
+static void update_pgdat_span(struct pglist_data *pgdat)
+{
+	unsigned long node_start_pfn = 0, node_end_pfn = 0;
+	struct zone *zone;
+
+	for (zone = pgdat->node_zones;
+	     zone < pgdat->node_zones + MAX_NR_ZONES; zone++) {
+		unsigned long end_pfn = zone_end_pfn(zone);
+
+		/* No need to lock the zones, they can't change. */
+		if (!zone->spanned_pages)
+			continue;
+		if (!node_end_pfn) {
+			node_start_pfn = zone->zone_start_pfn;
+			node_end_pfn = end_pfn;
+			continue;
+		}
+
+		if (end_pfn > node_end_pfn)
+			node_end_pfn = end_pfn;
+		if (zone->zone_start_pfn < node_start_pfn)
+			node_start_pfn = zone->zone_start_pfn;
+	}
+
+	pgdat->node_start_pfn = node_start_pfn;
+	pgdat->node_spanned_pages = node_end_pfn - node_start_pfn;
+}
+
+void __ref remove_pfn_range_from_zone(struct zone *zone,
+				      unsigned long start_pfn,
+				      unsigned long nr_pages)
+{
+	const unsigned long end_pfn = start_pfn + nr_pages;
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	unsigned long pfn, cur_nr_pages;
+
+	/* Poison struct pages because they are now uninitialized again. */
+	for (pfn = start_pfn; pfn < end_pfn; pfn += cur_nr_pages) {
+		cond_resched();
+
+		/* Select all remaining pages up to the next section boundary */
+		cur_nr_pages =
+			min(end_pfn - pfn, SECTION_ALIGN_UP(pfn + 1) - pfn);
+		page_init_poison(pfn_to_page(pfn),
+				 sizeof(struct page) * cur_nr_pages);
+	}
+
+	/*
+	 * Zone shrinking code cannot properly deal with ZONE_DEVICE. So
+	 * we will not try to shrink the zones - which is okay as
+	 * set_zone_contiguous() cannot deal with ZONE_DEVICE either way.
+	 */
+	if (zone_is_zone_device(zone))
+		return;
+
+	clear_zone_contiguous(zone);
+
+	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
+	update_pgdat_span(pgdat);
+
+	set_zone_contiguous(zone);
+}
+
+static void __remove_section(unsigned long pfn, unsigned long nr_pages,
+			     unsigned long map_offset,
+			     struct vmem_altmap *altmap)
+{
+	struct mem_section *ms = __pfn_to_section(pfn);
+
+	if (WARN_ON_ONCE(!valid_section(ms)))
+		return;
+
+	sparse_remove_section(ms, pfn, nr_pages, map_offset, altmap);
+}
+
+/**
+ * __remove_pages() - remove sections of pages
+ * @pfn: starting pageframe (must be aligned to start of a section)
+ * @nr_pages: number of pages to remove (must be multiple of section size)
+ * @altmap: alternative device page map or %NULL if default memmap is used
+ *
+ * Generic helper function to remove section mappings and sysfs entries
+ * for the section of the memory we are removing. Caller needs to make
+ * sure that pages are marked reserved and zones are adjust properly by
+ * calling offline_pages().
+ */
+void __remove_pages(unsigned long pfn, unsigned long nr_pages,
+		    struct vmem_altmap *altmap)
+{
+	const unsigned long end_pfn = pfn + nr_pages;
+	unsigned long cur_nr_pages;
+	unsigned long map_offset = 0;
+
+	map_offset = vmem_altmap_offset(altmap);
+
+	if (check_pfn_span(pfn, nr_pages)) {
+		WARN(1, "Misaligned %s start: %#lx end: #%lx\n", __func__, pfn, pfn + nr_pages - 1);
+		return;
+	}
+
+	for (; pfn < end_pfn; pfn += cur_nr_pages) {
+		cond_resched();
+		/* Select all remaining pages up to the next section boundary */
+		cur_nr_pages = min(end_pfn - pfn,
+				   SECTION_ALIGN_UP(pfn + 1) - pfn);
+		__remove_section(pfn, cur_nr_pages, map_offset, altmap);
+		map_offset = 0;
+	}
+}
+
+int set_online_page_callback(online_page_callback_t callback)
+{
+	int rc = -EINVAL;
+
+	get_online_mems();
+	mutex_lock(&online_page_callback_lock);
+
+	if (online_page_callback == generic_online_page) {
+		online_page_callback = callback;
+		rc = 0;
+	}
+
+	mutex_unlock(&online_page_callback_lock);
+	put_online_mems();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(set_online_page_callback);
+
+int restore_online_page_callback(online_page_callback_t callback)
+{
+	int rc = -EINVAL;
+
+	get_online_mems();
+	mutex_lock(&online_page_callback_lock);
+
+	if (online_page_callback == callback) {
+		online_page_callback = generic_online_page;
+		rc = 0;
+	}
+
+	mutex_unlock(&online_page_callback_lock);
+	put_online_mems();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(restore_online_page_callback);
+
+void generic_online_page(struct page *page, unsigned int order)
+{
+	/*
+	 * Freeing the page with debug_pagealloc enabled will try to unmap it,
+	 * so we should map it first. This is better than introducing a special
+	 * case in page freeing fast path.
+	 */
+	debug_pagealloc_map_pages(page, 1 << order);
+	__free_pages_core(page, order);
+	totalram_pages_add(1UL << order);
+}
+EXPORT_SYMBOL_GPL(generic_online_page);
+
+static void online_pages_range(unsigned long start_pfn, unsigned long nr_pages)
+{
+	const unsigned long end_pfn = start_pfn + nr_pages;
+	unsigned long pfn;
+
+	/*
+	 * Online the pages in MAX_ORDER - 1 aligned chunks. The callback might
+	 * decide to not expose all pages to the buddy (e.g., expose them
+	 * later). We account all pages as being online and belonging to this
+	 * zone ("present").
+	 * When using memmap_on_memory, the range might not be aligned to
+	 * MAX_ORDER_NR_PAGES - 1, but pageblock aligned. __ffs() will detect
+	 * this and the first chunk to online will be pageblock_nr_pages.
+	 */
+	for (pfn = start_pfn; pfn < end_pfn;) {
+		int order = min(MAX_ORDER - 1UL, __ffs(pfn));
+
+		(*online_page_callback)(pfn_to_page(pfn), order);
+		pfn += (1UL << order);
+	}
+
+	/* mark all involved sections as online */
+	online_mem_sections(start_pfn, end_pfn);
+}
+
+/* check which state of node_states will be changed when online memory */
+static void node_states_check_changes_online(unsigned long nr_pages,
+	struct zone *zone, struct memory_notify *arg)
+{
+	int nid = zone_to_nid(zone);
+
+	arg->status_change_nid = NUMA_NO_NODE;
+	arg->status_change_nid_normal = NUMA_NO_NODE;
+
+	if (!node_state(nid, N_MEMORY))
+		arg->status_change_nid = nid;
+	if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY))
+		arg->status_change_nid_normal = nid;
+}
+
+static void node_states_set_node(int node, struct memory_notify *arg)
+{
+	if (arg->status_change_nid_normal >= 0)
+		node_set_state(node, N_NORMAL_MEMORY);
+
+	if (arg->status_change_nid >= 0)
+		node_set_state(node, N_MEMORY);
+}
+
+static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
+		unsigned long nr_pages)
+{
+	unsigned long old_end_pfn = zone_end_pfn(zone);
+
+	if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn)
+		zone->zone_start_pfn = start_pfn;
+
+	zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn;
+}
+
+static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned long start_pfn,
+                                     unsigned long nr_pages)
+{
+	unsigned long old_end_pfn = pgdat_end_pfn(pgdat);
+
+	if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn)
+		pgdat->node_start_pfn = start_pfn;
+
+	pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn;
+
+}
+
+#ifdef CONFIG_ZONE_DEVICE
+static void section_taint_zone_device(unsigned long pfn)
+{
+	struct mem_section *ms = __pfn_to_section(pfn);
+
+	ms->section_mem_map |= SECTION_TAINT_ZONE_DEVICE;
+}
+#else
+static inline void section_taint_zone_device(unsigned long pfn)
+{
+}
+#endif
+
+/*
+ * Associate the pfn range with the given zone, initializing the memmaps
+ * and resizing the pgdat/zone data to span the added pages. After this
+ * call, all affected pages are PG_reserved.
+ *
+ * All aligned pageblocks are initialized to the specified migratetype
+ * (usually MIGRATE_MOVABLE). Besides setting the migratetype, no related
+ * zone stats (e.g., nr_isolate_pageblock) are touched.
+ */
+void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
+				  unsigned long nr_pages,
+				  struct vmem_altmap *altmap, int migratetype)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	int nid = pgdat->node_id;
+
+	clear_zone_contiguous(zone);
+
+	if (zone_is_empty(zone))
+		init_currently_empty_zone(zone, start_pfn, nr_pages);
+	resize_zone_range(zone, start_pfn, nr_pages);
+	resize_pgdat_range(pgdat, start_pfn, nr_pages);
+
+	/*
+	 * Subsection population requires care in pfn_to_online_page().
+	 * Set the taint to enable the slow path detection of
+	 * ZONE_DEVICE pages in an otherwise  ZONE_{NORMAL,MOVABLE}
+	 * section.
+	 */
+	if (zone_is_zone_device(zone)) {
+		if (!IS_ALIGNED(start_pfn, PAGES_PER_SECTION))
+			section_taint_zone_device(start_pfn);
+		if (!IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION))
+			section_taint_zone_device(start_pfn + nr_pages);
+	}
+
+	/*
+	 * TODO now we have a visible range of pages which are not associated
+	 * with their zone properly. Not nice but set_pfnblock_flags_mask
+	 * expects the zone spans the pfn range. All the pages in the range
+	 * are reserved so nobody should be touching them so we should be safe
+	 */
+	memmap_init_range(nr_pages, nid, zone_idx(zone), start_pfn, 0,
+			 MEMINIT_HOTPLUG, altmap, migratetype);
+
+	set_zone_contiguous(zone);
+}
+
+struct auto_movable_stats {
+	unsigned long kernel_early_pages;
+	unsigned long movable_pages;
+};
+
+static void auto_movable_stats_account_zone(struct auto_movable_stats *stats,
+					    struct zone *zone)
+{
+	if (zone_idx(zone) == ZONE_MOVABLE) {
+		stats->movable_pages += zone->present_pages;
+	} else {
+		stats->kernel_early_pages += zone->present_early_pages;
+#ifdef CONFIG_CMA
+		/*
+		 * CMA pages (never on hotplugged memory) behave like
+		 * ZONE_MOVABLE.
+		 */
+		stats->movable_pages += zone->cma_pages;
+		stats->kernel_early_pages -= zone->cma_pages;
+#endif /* CONFIG_CMA */
+	}
+}
+struct auto_movable_group_stats {
+	unsigned long movable_pages;
+	unsigned long req_kernel_early_pages;
+};
+
+static int auto_movable_stats_account_group(struct memory_group *group,
+					   void *arg)
+{
+	const int ratio = READ_ONCE(auto_movable_ratio);
+	struct auto_movable_group_stats *stats = arg;
+	long pages;
+
+	/*
+	 * We don't support modifying the config while the auto-movable online
+	 * policy is already enabled. Just avoid the division by zero below.
+	 */
+	if (!ratio)
+		return 0;
+
+	/*
+	 * Calculate how many early kernel pages this group requires to
+	 * satisfy the configured zone ratio.
+	 */
+	pages = group->present_movable_pages * 100 / ratio;
+	pages -= group->present_kernel_pages;
+
+	if (pages > 0)
+		stats->req_kernel_early_pages += pages;
+	stats->movable_pages += group->present_movable_pages;
+	return 0;
+}
+
+static bool auto_movable_can_online_movable(int nid, struct memory_group *group,
+					    unsigned long nr_pages)
+{
+	unsigned long kernel_early_pages, movable_pages;
+	struct auto_movable_group_stats group_stats = {};
+	struct auto_movable_stats stats = {};
+	pg_data_t *pgdat = NODE_DATA(nid);
+	struct zone *zone;
+	int i;
+
+	/* Walk all relevant zones and collect MOVABLE vs. KERNEL stats. */
+	if (nid == NUMA_NO_NODE) {
+		/* TODO: cache values */
+		for_each_populated_zone(zone)
+			auto_movable_stats_account_zone(&stats, zone);
+	} else {
+		for (i = 0; i < MAX_NR_ZONES; i++) {
+			zone = pgdat->node_zones + i;
+			if (populated_zone(zone))
+				auto_movable_stats_account_zone(&stats, zone);
+		}
+	}
+
+	kernel_early_pages = stats.kernel_early_pages;
+	movable_pages = stats.movable_pages;
+
+	/*
+	 * Kernel memory inside dynamic memory group allows for more MOVABLE
+	 * memory within the same group. Remove the effect of all but the
+	 * current group from the stats.
+	 */
+	walk_dynamic_memory_groups(nid, auto_movable_stats_account_group,
+				   group, &group_stats);
+	if (kernel_early_pages <= group_stats.req_kernel_early_pages)
+		return false;
+	kernel_early_pages -= group_stats.req_kernel_early_pages;
+	movable_pages -= group_stats.movable_pages;
+
+	if (group && group->is_dynamic)
+		kernel_early_pages += group->present_kernel_pages;
+
+	/*
+	 * Test if we could online the given number of pages to ZONE_MOVABLE
+	 * and still stay in the configured ratio.
+	 */
+	movable_pages += nr_pages;
+	return movable_pages <= (auto_movable_ratio * kernel_early_pages) / 100;
+}
+
+/*
+ * Returns a default kernel memory zone for the given pfn range.
+ * If no kernel zone covers this pfn range it will automatically go
+ * to the ZONE_NORMAL.
+ */
+static struct zone *default_kernel_zone_for_pfn(int nid, unsigned long start_pfn,
+		unsigned long nr_pages)
+{
+	struct pglist_data *pgdat = NODE_DATA(nid);
+	int zid;
+
+	for (zid = 0; zid < ZONE_NORMAL; zid++) {
+		struct zone *zone = &pgdat->node_zones[zid];
+
+		if (zone_intersects(zone, start_pfn, nr_pages))
+			return zone;
+	}
+
+	return &pgdat->node_zones[ZONE_NORMAL];
+}
+
+/*
+ * Determine to which zone to online memory dynamically based on user
+ * configuration and system stats. We care about the following ratio:
+ *
+ *   MOVABLE : KERNEL
+ *
+ * Whereby MOVABLE is memory in ZONE_MOVABLE and KERNEL is memory in
+ * one of the kernel zones. CMA pages inside one of the kernel zones really
+ * behaves like ZONE_MOVABLE, so we treat them accordingly.
+ *
+ * We don't allow for hotplugged memory in a KERNEL zone to increase the
+ * amount of MOVABLE memory we can have, so we end up with:
+ *
+ *   MOVABLE : KERNEL_EARLY
+ *
+ * Whereby KERNEL_EARLY is memory in one of the kernel zones, available sinze
+ * boot. We base our calculation on KERNEL_EARLY internally, because:
+ *
+ * a) Hotplugged memory in one of the kernel zones can sometimes still get
+ *    hotunplugged, especially when hot(un)plugging individual memory blocks.
+ *    There is no coordination across memory devices, therefore "automatic"
+ *    hotunplugging, as implemented in hypervisors, could result in zone
+ *    imbalances.
+ * b) Early/boot memory in one of the kernel zones can usually not get
+ *    hotunplugged again (e.g., no firmware interface to unplug, fragmented
+ *    with unmovable allocations). While there are corner cases where it might
+ *    still work, it is barely relevant in practice.
+ *
+ * Exceptions are dynamic memory groups, which allow for more MOVABLE
+ * memory within the same memory group -- because in that case, there is
+ * coordination within the single memory device managed by a single driver.
+ *
+ * We rely on "present pages" instead of "managed pages", as the latter is
+ * highly unreliable and dynamic in virtualized environments, and does not
+ * consider boot time allocations. For example, memory ballooning adjusts the
+ * managed pages when inflating/deflating the balloon, and balloon compaction
+ * can even migrate inflated pages between zones.
+ *
+ * Using "present pages" is better but some things to keep in mind are:
+ *
+ * a) Some memblock allocations, such as for the crashkernel area, are
+ *    effectively unused by the kernel, yet they account to "present pages".
+ *    Fortunately, these allocations are comparatively small in relevant setups
+ *    (e.g., fraction of system memory).
+ * b) Some hotplugged memory blocks in virtualized environments, esecially
+ *    hotplugged by virtio-mem, look like they are completely present, however,
+ *    only parts of the memory block are actually currently usable.
+ *    "present pages" is an upper limit that can get reached at runtime. As
+ *    we base our calculations on KERNEL_EARLY, this is not an issue.
+ */
+static struct zone *auto_movable_zone_for_pfn(int nid,
+					      struct memory_group *group,
+					      unsigned long pfn,
+					      unsigned long nr_pages)
+{
+	unsigned long online_pages = 0, max_pages, end_pfn;
+	struct page *page;
+
+	if (!auto_movable_ratio)
+		goto kernel_zone;
+
+	if (group && !group->is_dynamic) {
+		max_pages = group->s.max_pages;
+		online_pages = group->present_movable_pages;
+
+		/* If anything is !MOVABLE online the rest !MOVABLE. */
+		if (group->present_kernel_pages)
+			goto kernel_zone;
+	} else if (!group || group->d.unit_pages == nr_pages) {
+		max_pages = nr_pages;
+	} else {
+		max_pages = group->d.unit_pages;
+		/*
+		 * Take a look at all online sections in the current unit.
+		 * We can safely assume that all pages within a section belong
+		 * to the same zone, because dynamic memory groups only deal
+		 * with hotplugged memory.
+		 */
+		pfn = ALIGN_DOWN(pfn, group->d.unit_pages);
+		end_pfn = pfn + group->d.unit_pages;
+		for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+			page = pfn_to_online_page(pfn);
+			if (!page)
+				continue;
+			/* If anything is !MOVABLE online the rest !MOVABLE. */
+			if (!is_zone_movable_page(page))
+				goto kernel_zone;
+			online_pages += PAGES_PER_SECTION;
+		}
+	}
+
+	/*
+	 * Online MOVABLE if we could *currently* online all remaining parts
+	 * MOVABLE. We expect to (add+) online them immediately next, so if
+	 * nobody interferes, all will be MOVABLE if possible.
+	 */
+	nr_pages = max_pages - online_pages;
+	if (!auto_movable_can_online_movable(NUMA_NO_NODE, group, nr_pages))
+		goto kernel_zone;
+
+#ifdef CONFIG_NUMA
+	if (auto_movable_numa_aware &&
+	    !auto_movable_can_online_movable(nid, group, nr_pages))
+		goto kernel_zone;
+#endif /* CONFIG_NUMA */
+
+	return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
+kernel_zone:
+	return default_kernel_zone_for_pfn(nid, pfn, nr_pages);
+}
+
+static inline struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
+		unsigned long nr_pages)
+{
+	struct zone *kernel_zone = default_kernel_zone_for_pfn(nid, start_pfn,
+			nr_pages);
+	struct zone *movable_zone = &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
+	bool in_kernel = zone_intersects(kernel_zone, start_pfn, nr_pages);
+	bool in_movable = zone_intersects(movable_zone, start_pfn, nr_pages);
+
+	/*
+	 * We inherit the existing zone in a simple case where zones do not
+	 * overlap in the given range
+	 */
+	if (in_kernel ^ in_movable)
+		return (in_kernel) ? kernel_zone : movable_zone;
+
+	/*
+	 * If the range doesn't belong to any zone or two zones overlap in the
+	 * given range then we use movable zone only if movable_node is
+	 * enabled because we always online to a kernel zone by default.
+	 */
+	return movable_node_enabled ? movable_zone : kernel_zone;
+}
+
+struct zone *zone_for_pfn_range(int online_type, int nid,
+		struct memory_group *group, unsigned long start_pfn,
+		unsigned long nr_pages)
+{
+	if (online_type == MMOP_ONLINE_KERNEL)
+		return default_kernel_zone_for_pfn(nid, start_pfn, nr_pages);
+
+	if (online_type == MMOP_ONLINE_MOVABLE)
+		return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
+
+	if (online_policy == ONLINE_POLICY_AUTO_MOVABLE)
+		return auto_movable_zone_for_pfn(nid, group, start_pfn, nr_pages);
+
+	return default_zone_for_pfn(nid, start_pfn, nr_pages);
+}
+
+/*
+ * This function should only be called by memory_block_{online,offline},
+ * and {online,offline}_pages.
+ */
+void adjust_present_page_count(struct page *page, struct memory_group *group,
+			       long nr_pages)
+{
+	struct zone *zone = page_zone(page);
+	const bool movable = zone_idx(zone) == ZONE_MOVABLE;
+
+	/*
+	 * We only support onlining/offlining/adding/removing of complete
+	 * memory blocks; therefore, either all is either early or hotplugged.
+	 */
+	if (early_section(__pfn_to_section(page_to_pfn(page))))
+		zone->present_early_pages += nr_pages;
+	zone->present_pages += nr_pages;
+	zone->zone_pgdat->node_present_pages += nr_pages;
+
+	if (group && movable)
+		group->present_movable_pages += nr_pages;
+	else if (group && !movable)
+		group->present_kernel_pages += nr_pages;
+}
+
+int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
+			      struct zone *zone)
+{
+	unsigned long end_pfn = pfn + nr_pages;
+	int ret, i;
+
+	ret = kasan_add_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
+	if (ret)
+		return ret;
+
+	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE);
+
+	for (i = 0; i < nr_pages; i++)
+		SetPageVmemmapSelfHosted(pfn_to_page(pfn + i));
+
+	/*
+	 * It might be that the vmemmap_pages fully span sections. If that is
+	 * the case, mark those sections online here as otherwise they will be
+	 * left offline.
+	 */
+	if (nr_pages >= PAGES_PER_SECTION)
+	        online_mem_sections(pfn, ALIGN_DOWN(end_pfn, PAGES_PER_SECTION));
+
+	return ret;
+}
+
+void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long nr_pages)
+{
+	unsigned long end_pfn = pfn + nr_pages;
+
+	/*
+	 * It might be that the vmemmap_pages fully span sections. If that is
+	 * the case, mark those sections offline here as otherwise they will be
+	 * left online.
+	 */
+	if (nr_pages >= PAGES_PER_SECTION)
+		offline_mem_sections(pfn, ALIGN_DOWN(end_pfn, PAGES_PER_SECTION));
+
+        /*
+	 * The pages associated with this vmemmap have been offlined, so
+	 * we can reset its state here.
+	 */
+	remove_pfn_range_from_zone(page_zone(pfn_to_page(pfn)), pfn, nr_pages);
+	kasan_remove_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
+}
+
+/*
+ * Must be called with mem_hotplug_lock in write mode.
+ */
+int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
+		       struct zone *zone, struct memory_group *group)
+{
+	unsigned long flags;
+	int need_zonelists_rebuild = 0;
+	const int nid = zone_to_nid(zone);
+	int ret;
+	struct memory_notify arg;
+
+	/*
+	 * {on,off}lining is constrained to full memory sections (or more
+	 * precisely to memory blocks from the user space POV).
+	 * memmap_on_memory is an exception because it reserves initial part
+	 * of the physical memory space for vmemmaps. That space is pageblock
+	 * aligned.
+	 */
+	if (WARN_ON_ONCE(!nr_pages || !pageblock_aligned(pfn) ||
+			 !IS_ALIGNED(pfn + nr_pages, PAGES_PER_SECTION)))
+		return -EINVAL;
+
+
+	/* associate pfn range with the zone */
+	move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_ISOLATE);
+
+	arg.start_pfn = pfn;
+	arg.nr_pages = nr_pages;
+	node_states_check_changes_online(nr_pages, zone, &arg);
+
+	ret = memory_notify(MEM_GOING_ONLINE, &arg);
+	ret = notifier_to_errno(ret);
+	if (ret)
+		goto failed_addition;
+
+	/*
+	 * Fixup the number of isolated pageblocks before marking the sections
+	 * onlining, such that undo_isolate_page_range() works correctly.
+	 */
+	spin_lock_irqsave(&zone->lock, flags);
+	zone->nr_isolate_pageblock += nr_pages / pageblock_nr_pages;
+	spin_unlock_irqrestore(&zone->lock, flags);
+
+	/*
+	 * If this zone is not populated, then it is not in zonelist.
+	 * This means the page allocator ignores this zone.
+	 * So, zonelist must be updated after online.
+	 */
+	if (!populated_zone(zone)) {
+		need_zonelists_rebuild = 1;
+		setup_zone_pageset(zone);
+	}
+
+	online_pages_range(pfn, nr_pages);
+	adjust_present_page_count(pfn_to_page(pfn), group, nr_pages);
+
+	node_states_set_node(nid, &arg);
+	if (need_zonelists_rebuild)
+		build_all_zonelists(NULL);
+
+	/* Basic onlining is complete, allow allocation of onlined pages. */
+	undo_isolate_page_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE);
+
+	/*
+	 * Freshly onlined pages aren't shuffled (e.g., all pages are placed to
+	 * the tail of the freelist when undoing isolation). Shuffle the whole
+	 * zone to make sure the just onlined pages are properly distributed
+	 * across the whole freelist - to create an initial shuffle.
+	 */
+	shuffle_zone(zone);
+
+	/* reinitialise watermarks and update pcp limits */
+	init_per_zone_wmark_min();
+
+	kswapd_run(nid);
+	kcompactd_run(nid);
+
+	writeback_set_ratelimit();
+
+	memory_notify(MEM_ONLINE, &arg);
+	return 0;
+
+failed_addition:
+	pr_debug("online_pages [mem %#010llx-%#010llx] failed\n",
+		 (unsigned long long) pfn << PAGE_SHIFT,
+		 (((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
+	memory_notify(MEM_CANCEL_ONLINE, &arg);
+	remove_pfn_range_from_zone(zone, pfn, nr_pages);
+	return ret;
+}
+
+static void reset_node_present_pages(pg_data_t *pgdat)
+{
+	struct zone *z;
+
+	for (z = pgdat->node_zones; z < pgdat->node_zones + MAX_NR_ZONES; z++)
+		z->present_pages = 0;
+
+	pgdat->node_present_pages = 0;
+}
+
+/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
+static pg_data_t __ref *hotadd_init_pgdat(int nid)
+{
+	struct pglist_data *pgdat;
+
+	/*
+	 * NODE_DATA is preallocated (free_area_init) but its internal
+	 * state is not allocated completely. Add missing pieces.
+	 * Completely offline nodes stay around and they just need
+	 * reintialization.
+	 */
+	pgdat = NODE_DATA(nid);
+
+	/* init node's zones as empty zones, we don't have any present pages.*/
+	free_area_init_core_hotplug(pgdat);
+
+	/*
+	 * The node we allocated has no zone fallback lists. For avoiding
+	 * to access not-initialized zonelist, build here.
+	 */
+	build_all_zonelists(pgdat);
+
+	/*
+	 * When memory is hot-added, all the memory is in offline state. So
+	 * clear all zones' present_pages because they will be updated in
+	 * online_pages() and offline_pages().
+	 * TODO: should be in free_area_init_core_hotplug?
+	 */
+	reset_node_managed_pages(pgdat);
+	reset_node_present_pages(pgdat);
+
+	return pgdat;
+}
+
+/*
+ * __try_online_node - online a node if offlined
+ * @nid: the node ID
+ * @set_node_online: Whether we want to online the node
+ * called by cpu_up() to online a node without onlined memory.
+ *
+ * Returns:
+ * 1 -> a new node has been allocated
+ * 0 -> the node is already online
+ * -ENOMEM -> the node could not be allocated
+ */
+static int __try_online_node(int nid, bool set_node_online)
+{
+	pg_data_t *pgdat;
+	int ret = 1;
+
+	if (node_online(nid))
+		return 0;
+
+	pgdat = hotadd_init_pgdat(nid);
+	if (!pgdat) {
+		pr_err("Cannot online node %d due to NULL pgdat\n", nid);
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (set_node_online) {
+		node_set_online(nid);
+		ret = register_one_node(nid);
+		BUG_ON(ret);
+	}
+out:
+	return ret;
+}
+
+/*
+ * Users of this function always want to online/register the node
+ */
+int try_online_node(int nid)
+{
+	int ret;
+
+	mem_hotplug_begin();
+	ret =  __try_online_node(nid, true);
+	mem_hotplug_done();
+	return ret;
+}
+
+static int check_hotplug_memory_range(u64 start, u64 size)
+{
+	/* memory range must be block size aligned */
+	if (!size || !IS_ALIGNED(start, memory_block_size_bytes()) ||
+	    !IS_ALIGNED(size, memory_block_size_bytes())) {
+		pr_err("Block size [%#lx] unaligned hotplug range: start %#llx, size %#llx",
+		       memory_block_size_bytes(), start, size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int online_memory_block(struct memory_block *mem, void *arg)
+{
+	mem->online_type = mhp_default_online_type;
+	return device_online(&mem->dev);
+}
+
+bool mhp_supports_memmap_on_memory(unsigned long size)
+{
+	unsigned long nr_vmemmap_pages = size / PAGE_SIZE;
+	unsigned long vmemmap_size = nr_vmemmap_pages * sizeof(struct page);
+	unsigned long remaining_size = size - vmemmap_size;
+
+	/*
+	 * Besides having arch support and the feature enabled at runtime, we
+	 * need a few more assumptions to hold true:
+	 *
+	 * a) We span a single memory block: memory onlining/offlinin;g happens
+	 *    in memory block granularity. We don't want the vmemmap of online
+	 *    memory blocks to reside on offline memory blocks. In the future,
+	 *    we might want to support variable-sized memory blocks to make the
+	 *    feature more versatile.
+	 *
+	 * b) The vmemmap pages span complete PMDs: We don't want vmemmap code
+	 *    to populate memory from the altmap for unrelated parts (i.e.,
+	 *    other memory blocks)
+	 *
+	 * c) The vmemmap pages (and thereby the pages that will be exposed to
+	 *    the buddy) have to cover full pageblocks: memory onlining/offlining
+	 *    code requires applicable ranges to be page-aligned, for example, to
+	 *    set the migratetypes properly.
+	 *
+	 * TODO: Although we have a check here to make sure that vmemmap pages
+	 *       fully populate a PMD, it is not the right place to check for
+	 *       this. A much better solution involves improving vmemmap code
+	 *       to fallback to base pages when trying to populate vmemmap using
+	 *       altmap as an alternative source of memory, and we do not exactly
+	 *       populate a single PMD.
+	 */
+	return mhp_memmap_on_memory() &&
+	       size == memory_block_size_bytes() &&
+	       IS_ALIGNED(vmemmap_size, PMD_SIZE) &&
+	       IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT));
+}
+
+/*
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations (triggered e.g. by sysfs).
+ *
+ * we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG
+ */
+int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
+{
+	struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
+	enum memblock_flags memblock_flags = MEMBLOCK_NONE;
+	struct vmem_altmap mhp_altmap = {};
+	struct memory_group *group = NULL;
+	u64 start, size;
+	bool new_node = false;
+	int ret;
+
+	start = res->start;
+	size = resource_size(res);
+
+	ret = check_hotplug_memory_range(start, size);
+	if (ret)
+		return ret;
+
+	if (mhp_flags & MHP_NID_IS_MGID) {
+		group = memory_group_find_by_id(nid);
+		if (!group)
+			return -EINVAL;
+		nid = group->nid;
+	}
+
+	if (!node_possible(nid)) {
+		WARN(1, "node %d was absent from the node_possible_map\n", nid);
+		return -EINVAL;
+	}
+
+	mem_hotplug_begin();
+
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
+		if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
+			memblock_flags = MEMBLOCK_DRIVER_MANAGED;
+		ret = memblock_add_node(start, size, nid, memblock_flags);
+		if (ret)
+			goto error_mem_hotplug_end;
+	}
+
+	ret = __try_online_node(nid, false);
+	if (ret < 0)
+		goto error;
+	new_node = ret;
+
+	/*
+	 * Self hosted memmap array
+	 */
+	if (mhp_flags & MHP_MEMMAP_ON_MEMORY) {
+		if (!mhp_supports_memmap_on_memory(size)) {
+			ret = -EINVAL;
+			goto error;
+		}
+		mhp_altmap.free = PHYS_PFN(size);
+		mhp_altmap.base_pfn = PHYS_PFN(start);
+		params.altmap = &mhp_altmap;
+	}
+
+	/* call arch's memory hotadd */
+	ret = arch_add_memory(nid, start, size, &params);
+	if (ret < 0)
+		goto error;
+
+	/* create memory block devices after memory was added */
+	ret = create_memory_block_devices(start, size, mhp_altmap.alloc,
+					  group);
+	if (ret) {
+		arch_remove_memory(start, size, params.altmap);
+		goto error;
+	}
+
+	if (new_node) {
+		/* If sysfs file of new node can't be created, cpu on the node
+		 * can't be hot-added. There is no rollback way now.
+		 * So, check by BUG_ON() to catch it reluctantly..
+		 * We online node here. We can't roll back from here.
+		 */
+		node_set_online(nid);
+		ret = __register_one_node(nid);
+		BUG_ON(ret);
+	}
+
+	register_memory_blocks_under_node(nid, PFN_DOWN(start),
+					  PFN_UP(start + size - 1),
+					  MEMINIT_HOTPLUG);
+
+	/* create new memmap entry */
+	if (!strcmp(res->name, "System RAM"))
+		firmware_map_add_hotplug(start, start + size, "System RAM");
+
+	/* device_online() will take the lock when calling online_pages() */
+	mem_hotplug_done();
+
+	/*
+	 * In case we're allowed to merge the resource, flag it and trigger
+	 * merging now that adding succeeded.
+	 */
+	if (mhp_flags & MHP_MERGE_RESOURCE)
+		merge_system_ram_resource(res);
+
+	/* online pages if requested */
+	if (mhp_default_online_type != MMOP_OFFLINE)
+		walk_memory_blocks(start, size, NULL, online_memory_block);
+
+	return ret;
+error:
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
+		memblock_remove(start, size);
+error_mem_hotplug_end:
+	mem_hotplug_done();
+	return ret;
+}
+
+/* requires device_hotplug_lock, see add_memory_resource() */
+int __ref __add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
+{
+	struct resource *res;
+	int ret;
+
+	res = register_memory_resource(start, size, "System RAM");
+	if (IS_ERR(res))
+		return PTR_ERR(res);
+
+	ret = add_memory_resource(nid, res, mhp_flags);
+	if (ret < 0)
+		release_memory_resource(res);
+	return ret;
+}
+
+int add_memory(int nid, u64 start, u64 size, mhp_t mhp_flags)
+{
+	int rc;
+
+	lock_device_hotplug();
+	rc = __add_memory(nid, start, size, mhp_flags);
+	unlock_device_hotplug();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(add_memory);
+
+/*
+ * Add special, driver-managed memory to the system as system RAM. Such
+ * memory is not exposed via the raw firmware-provided memmap as system
+ * RAM, instead, it is detected and added by a driver - during cold boot,
+ * after a reboot, and after kexec.
+ *
+ * Reasons why this memory should not be used for the initial memmap of a
+ * kexec kernel or for placing kexec images:
+ * - The booting kernel is in charge of determining how this memory will be
+ *   used (e.g., use persistent memory as system RAM)
+ * - Coordination with a hypervisor is required before this memory
+ *   can be used (e.g., inaccessible parts).
+ *
+ * For this memory, no entries in /sys/firmware/memmap ("raw firmware-provided
+ * memory map") are created. Also, the created memory resource is flagged
+ * with IORESOURCE_SYSRAM_DRIVER_MANAGED, so in-kernel users can special-case
+ * this memory as well (esp., not place kexec images onto it).
+ *
+ * The resource_name (visible via /proc/iomem) has to have the format
+ * "System RAM ($DRIVER)".
+ */
+int add_memory_driver_managed(int nid, u64 start, u64 size,
+			      const char *resource_name, mhp_t mhp_flags)
+{
+	struct resource *res;
+	int rc;
+
+	if (!resource_name ||
+	    strstr(resource_name, "System RAM (") != resource_name ||
+	    resource_name[strlen(resource_name) - 1] != ')')
+		return -EINVAL;
+
+	lock_device_hotplug();
+
+	res = register_memory_resource(start, size, resource_name);
+	if (IS_ERR(res)) {
+		rc = PTR_ERR(res);
+		goto out_unlock;
+	}
+
+	rc = add_memory_resource(nid, res, mhp_flags);
+	if (rc < 0)
+		release_memory_resource(res);
+
+out_unlock:
+	unlock_device_hotplug();
+	return rc;
+}
+EXPORT_SYMBOL_GPL(add_memory_driver_managed);
+
+/*
+ * Platforms should define arch_get_mappable_range() that provides
+ * maximum possible addressable physical memory range for which the
+ * linear mapping could be created. The platform returned address
+ * range must adhere to these following semantics.
+ *
+ * - range.start <= range.end
+ * - Range includes both end points [range.start..range.end]
+ *
+ * There is also a fallback definition provided here, allowing the
+ * entire possible physical address range in case any platform does
+ * not define arch_get_mappable_range().
+ */
+struct range __weak arch_get_mappable_range(void)
+{
+	struct range mhp_range = {
+		.start = 0UL,
+		.end = -1ULL,
+	};
+	return mhp_range;
+}
+
+struct range mhp_get_pluggable_range(bool need_mapping)
+{
+	const u64 max_phys = (1ULL << MAX_PHYSMEM_BITS) - 1;
+	struct range mhp_range;
+
+	if (need_mapping) {
+		mhp_range = arch_get_mappable_range();
+		if (mhp_range.start > max_phys) {
+			mhp_range.start = 0;
+			mhp_range.end = 0;
+		}
+		mhp_range.end = min_t(u64, mhp_range.end, max_phys);
+	} else {
+		mhp_range.start = 0;
+		mhp_range.end = max_phys;
+	}
+	return mhp_range;
+}
+EXPORT_SYMBOL_GPL(mhp_get_pluggable_range);
+
+bool mhp_range_allowed(u64 start, u64 size, bool need_mapping)
+{
+	struct range mhp_range = mhp_get_pluggable_range(need_mapping);
+	u64 end = start + size;
+
+	if (start < end && start >= mhp_range.start && (end - 1) <= mhp_range.end)
+		return true;
+
+	pr_warn("Hotplug memory [%#llx-%#llx] exceeds maximum addressable range [%#llx-%#llx]\n",
+		start, end, mhp_range.start, mhp_range.end);
+	return false;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
+ * non-lru movable pages and hugepages). Will skip over most unmovable
+ * pages (esp., pages that can be skipped when offlining), but bail out on
+ * definitely unmovable pages.
+ *
+ * Returns:
+ *	0 in case a movable page is found and movable_pfn was updated.
+ *	-ENOENT in case no movable page was found.
+ *	-EBUSY in case a definitely unmovable page was found.
+ */
+static int scan_movable_pages(unsigned long start, unsigned long end,
+			      unsigned long *movable_pfn)
+{
+	unsigned long pfn;
+
+	for (pfn = start; pfn < end; pfn++) {
+		struct page *page, *head;
+		unsigned long skip;
+
+		if (!pfn_valid(pfn))
+			continue;
+		page = pfn_to_page(pfn);
+		if (PageLRU(page))
+			goto found;
+		if (__PageMovable(page))
+			goto found;
+
+		/*
+		 * PageOffline() pages that are not marked __PageMovable() and
+		 * have a reference count > 0 (after MEM_GOING_OFFLINE) are
+		 * definitely unmovable. If their reference count would be 0,
+		 * they could at least be skipped when offlining memory.
+		 */
+		if (PageOffline(page) && page_count(page))
+			return -EBUSY;
+
+		if (!PageHuge(page))
+			continue;
+		head = compound_head(page);
+		/*
+		 * This test is racy as we hold no reference or lock.  The
+		 * hugetlb page could have been free'ed and head is no longer
+		 * a hugetlb page before the following check.  In such unlikely
+		 * cases false positives and negatives are possible.  Calling
+		 * code must deal with these scenarios.
+		 */
+		if (HPageMigratable(head))
+			goto found;
+		skip = compound_nr(head) - (pfn - page_to_pfn(head));
+		pfn += skip - 1;
+	}
+	return -ENOENT;
+found:
+	*movable_pfn = pfn;
+	return 0;
+}
+
+static int
+do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn;
+	struct page *page, *head;
+	int ret = 0;
+	LIST_HEAD(source);
+	static DEFINE_RATELIMIT_STATE(migrate_rs, DEFAULT_RATELIMIT_INTERVAL,
+				      DEFAULT_RATELIMIT_BURST);
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn++) {
+		struct folio *folio;
+
+		if (!pfn_valid(pfn))
+			continue;
+		page = pfn_to_page(pfn);
+		folio = page_folio(page);
+		head = &folio->page;
+
+		if (PageHuge(page)) {
+			pfn = page_to_pfn(head) + compound_nr(head) - 1;
+			isolate_hugetlb(head, &source);
+			continue;
+		} else if (PageTransHuge(page))
+			pfn = page_to_pfn(head) + thp_nr_pages(page) - 1;
+
+		/*
+		 * HWPoison pages have elevated reference counts so the migration would
+		 * fail on them. It also doesn't make any sense to migrate them in the
+		 * first place. Still try to unmap such a page in case it is still mapped
+		 * (e.g. current hwpoison implementation doesn't unmap KSM pages but keep
+		 * the unmap as the catch all safety net).
+		 */
+		if (PageHWPoison(page)) {
+			if (WARN_ON(folio_test_lru(folio)))
+				folio_isolate_lru(folio);
+			if (folio_mapped(folio))
+				try_to_unmap(folio, TTU_IGNORE_MLOCK);
+			continue;
+		}
+
+		if (!get_page_unless_zero(page))
+			continue;
+		/*
+		 * We can skip free pages. And we can deal with pages on
+		 * LRU and non-lru movable pages.
+		 */
+		if (PageLRU(page))
+			ret = isolate_lru_page(page);
+		else
+			ret = isolate_movable_page(page, ISOLATE_UNEVICTABLE);
+		if (!ret) { /* Success */
+			list_add_tail(&page->lru, &source);
+			if (!__PageMovable(page))
+				inc_node_page_state(page, NR_ISOLATED_ANON +
+						    page_is_file_lru(page));
+
+		} else {
+			if (__ratelimit(&migrate_rs)) {
+				pr_warn("failed to isolate pfn %lx\n", pfn);
+				dump_page(page, "isolation failed");
+			}
+		}
+		put_page(page);
+	}
+	if (!list_empty(&source)) {
+		nodemask_t nmask = node_states[N_MEMORY];
+		struct migration_target_control mtc = {
+			.nmask = &nmask,
+			.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
+		};
+
+		/*
+		 * We have checked that migration range is on a single zone so
+		 * we can use the nid of the first page to all the others.
+		 */
+		mtc.nid = page_to_nid(list_first_entry(&source, struct page, lru));
+
+		/*
+		 * try to allocate from a different node but reuse this node
+		 * if there are no other online nodes to be used (e.g. we are
+		 * offlining a part of the only existing node)
+		 */
+		node_clear(mtc.nid, nmask);
+		if (nodes_empty(nmask))
+			node_set(mtc.nid, nmask);
+		ret = migrate_pages(&source, alloc_migration_target, NULL,
+			(unsigned long)&mtc, MIGRATE_SYNC, MR_MEMORY_HOTPLUG, NULL);
+		if (ret) {
+			list_for_each_entry(page, &source, lru) {
+				if (__ratelimit(&migrate_rs)) {
+					pr_warn("migrating pfn %lx failed ret:%d\n",
+						page_to_pfn(page), ret);
+					dump_page(page, "migration failure");
+				}
+			}
+			putback_movable_pages(&source);
+		}
+	}
+
+	return ret;
+}
+
+static int __init cmdline_parse_movable_node(char *p)
+{
+	movable_node_enabled = true;
+	return 0;
+}
+early_param("movable_node", cmdline_parse_movable_node);
+
+/* check which state of node_states will be changed when offline memory */
+static void node_states_check_changes_offline(unsigned long nr_pages,
+		struct zone *zone, struct memory_notify *arg)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	unsigned long present_pages = 0;
+	enum zone_type zt;
+
+	arg->status_change_nid = NUMA_NO_NODE;
+	arg->status_change_nid_normal = NUMA_NO_NODE;
+
+	/*
+	 * Check whether node_states[N_NORMAL_MEMORY] will be changed.
+	 * If the memory to be offline is within the range
+	 * [0..ZONE_NORMAL], and it is the last present memory there,
+	 * the zones in that range will become empty after the offlining,
+	 * thus we can determine that we need to clear the node from
+	 * node_states[N_NORMAL_MEMORY].
+	 */
+	for (zt = 0; zt <= ZONE_NORMAL; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (zone_idx(zone) <= ZONE_NORMAL && nr_pages >= present_pages)
+		arg->status_change_nid_normal = zone_to_nid(zone);
+
+	/*
+	 * We have accounted the pages from [0..ZONE_NORMAL); ZONE_HIGHMEM
+	 * does not apply as we don't support 32bit.
+	 * Here we count the possible pages from ZONE_MOVABLE.
+	 * If after having accounted all the pages, we see that the nr_pages
+	 * to be offlined is over or equal to the accounted pages,
+	 * we know that the node will become empty, and so, we can clear
+	 * it for N_MEMORY as well.
+	 */
+	present_pages += pgdat->node_zones[ZONE_MOVABLE].present_pages;
+
+	if (nr_pages >= present_pages)
+		arg->status_change_nid = zone_to_nid(zone);
+}
+
+static void node_states_clear_node(int node, struct memory_notify *arg)
+{
+	if (arg->status_change_nid_normal >= 0)
+		node_clear_state(node, N_NORMAL_MEMORY);
+
+	if (arg->status_change_nid >= 0)
+		node_clear_state(node, N_MEMORY);
+}
+
+static int count_system_ram_pages_cb(unsigned long start_pfn,
+				     unsigned long nr_pages, void *data)
+{
+	unsigned long *nr_system_ram_pages = data;
+
+	*nr_system_ram_pages += nr_pages;
+	return 0;
+}
+
+/*
+ * Must be called with mem_hotplug_lock in write mode.
+ */
+int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
+			struct zone *zone, struct memory_group *group)
+{
+	const unsigned long end_pfn = start_pfn + nr_pages;
+	unsigned long pfn, system_ram_pages = 0;
+	const int node = zone_to_nid(zone);
+	unsigned long flags;
+	struct memory_notify arg;
+	char *reason;
+	int ret;
+
+	/*
+	 * {on,off}lining is constrained to full memory sections (or more
+	 * precisely to memory blocks from the user space POV).
+	 * memmap_on_memory is an exception because it reserves initial part
+	 * of the physical memory space for vmemmaps. That space is pageblock
+	 * aligned.
+	 */
+	if (WARN_ON_ONCE(!nr_pages || !pageblock_aligned(start_pfn) ||
+			 !IS_ALIGNED(start_pfn + nr_pages, PAGES_PER_SECTION)))
+		return -EINVAL;
+
+	/*
+	 * Don't allow to offline memory blocks that contain holes.
+	 * Consequently, memory blocks with holes can never get onlined
+	 * via the hotplug path - online_pages() - as hotplugged memory has
+	 * no holes. This way, we e.g., don't have to worry about marking
+	 * memory holes PG_reserved, don't need pfn_valid() checks, and can
+	 * avoid using walk_system_ram_range() later.
+	 */
+	walk_system_ram_range(start_pfn, nr_pages, &system_ram_pages,
+			      count_system_ram_pages_cb);
+	if (system_ram_pages != nr_pages) {
+		ret = -EINVAL;
+		reason = "memory holes";
+		goto failed_removal;
+	}
+
+	/*
+	 * We only support offlining of memory blocks managed by a single zone,
+	 * checked by calling code. This is just a sanity check that we might
+	 * want to remove in the future.
+	 */
+	if (WARN_ON_ONCE(page_zone(pfn_to_page(start_pfn)) != zone ||
+			 page_zone(pfn_to_page(end_pfn - 1)) != zone)) {
+		ret = -EINVAL;
+		reason = "multizone range";
+		goto failed_removal;
+	}
+
+	/*
+	 * Disable pcplists so that page isolation cannot race with freeing
+	 * in a way that pages from isolated pageblock are left on pcplists.
+	 */
+	zone_pcp_disable(zone);
+	lru_cache_disable();
+
+	/* set above range as isolated */
+	ret = start_isolate_page_range(start_pfn, end_pfn,
+				       MIGRATE_MOVABLE,
+				       MEMORY_OFFLINE | REPORT_FAILURE,
+				       GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL);
+	if (ret) {
+		reason = "failure to isolate range";
+		goto failed_removal_pcplists_disabled;
+	}
+
+	arg.start_pfn = start_pfn;
+	arg.nr_pages = nr_pages;
+	node_states_check_changes_offline(nr_pages, zone, &arg);
+
+	ret = memory_notify(MEM_GOING_OFFLINE, &arg);
+	ret = notifier_to_errno(ret);
+	if (ret) {
+		reason = "notifier failure";
+		goto failed_removal_isolated;
+	}
+
+	do {
+		pfn = start_pfn;
+		do {
+			if (signal_pending(current)) {
+				ret = -EINTR;
+				reason = "signal backoff";
+				goto failed_removal_isolated;
+			}
+
+			cond_resched();
+
+			ret = scan_movable_pages(pfn, end_pfn, &pfn);
+			if (!ret) {
+				/*
+				 * TODO: fatal migration failures should bail
+				 * out
+				 */
+				do_migrate_range(pfn, end_pfn);
+			}
+		} while (!ret);
+
+		if (ret != -ENOENT) {
+			reason = "unmovable page";
+			goto failed_removal_isolated;
+		}
+
+		/*
+		 * Dissolve free hugepages in the memory block before doing
+		 * offlining actually in order to make hugetlbfs's object
+		 * counting consistent.
+		 */
+		ret = dissolve_free_huge_pages(start_pfn, end_pfn);
+		if (ret) {
+			reason = "failure to dissolve huge pages";
+			goto failed_removal_isolated;
+		}
+
+		ret = test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE);
+
+	} while (ret);
+
+	/* Mark all sections offline and remove free pages from the buddy. */
+	__offline_isolated_pages(start_pfn, end_pfn);
+	pr_debug("Offlined Pages %ld\n", nr_pages);
+
+	/*
+	 * The memory sections are marked offline, and the pageblock flags
+	 * effectively stale; nobody should be touching them. Fixup the number
+	 * of isolated pageblocks, memory onlining will properly revert this.
+	 */
+	spin_lock_irqsave(&zone->lock, flags);
+	zone->nr_isolate_pageblock -= nr_pages / pageblock_nr_pages;
+	spin_unlock_irqrestore(&zone->lock, flags);
+
+	lru_cache_enable();
+	zone_pcp_enable(zone);
+
+	/* removal success */
+	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
+	adjust_present_page_count(pfn_to_page(start_pfn), group, -nr_pages);
+
+	/* reinitialise watermarks and update pcp limits */
+	init_per_zone_wmark_min();
+
+	if (!populated_zone(zone)) {
+		zone_pcp_reset(zone);
+		build_all_zonelists(NULL);
+	}
+
+	node_states_clear_node(node, &arg);
+	if (arg.status_change_nid >= 0) {
+		kcompactd_stop(node);
+		kswapd_stop(node);
+	}
+
+	writeback_set_ratelimit();
+
+	memory_notify(MEM_OFFLINE, &arg);
+	remove_pfn_range_from_zone(zone, start_pfn, nr_pages);
+	return 0;
+
+failed_removal_isolated:
+	/* pushback to free area */
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	memory_notify(MEM_CANCEL_OFFLINE, &arg);
+failed_removal_pcplists_disabled:
+	lru_cache_enable();
+	zone_pcp_enable(zone);
+failed_removal:
+	pr_debug("memory offlining [mem %#010llx-%#010llx] failed due to %s\n",
+		 (unsigned long long) start_pfn << PAGE_SHIFT,
+		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1,
+		 reason);
+	return ret;
+}
+
+static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
+{
+	int *nid = arg;
+
+	*nid = mem->nid;
+	if (unlikely(mem->state != MEM_OFFLINE)) {
+		phys_addr_t beginpa, endpa;
+
+		beginpa = PFN_PHYS(section_nr_to_pfn(mem->start_section_nr));
+		endpa = beginpa + memory_block_size_bytes() - 1;
+		pr_warn("removing memory fails, because memory [%pa-%pa] is onlined\n",
+			&beginpa, &endpa);
+
+		return -EBUSY;
+	}
+	return 0;
+}
+
+static int get_nr_vmemmap_pages_cb(struct memory_block *mem, void *arg)
+{
+	/*
+	 * If not set, continue with the next block.
+	 */
+	return mem->nr_vmemmap_pages;
+}
+
+static int check_cpu_on_node(int nid)
+{
+	int cpu;
+
+	for_each_present_cpu(cpu) {
+		if (cpu_to_node(cpu) == nid)
+			/*
+			 * the cpu on this node isn't removed, and we can't
+			 * offline this node.
+			 */
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+static int check_no_memblock_for_node_cb(struct memory_block *mem, void *arg)
+{
+	int nid = *(int *)arg;
+
+	/*
+	 * If a memory block belongs to multiple nodes, the stored nid is not
+	 * reliable. However, such blocks are always online (e.g., cannot get
+	 * offlined) and, therefore, are still spanned by the node.
+	 */
+	return mem->nid == nid ? -EEXIST : 0;
+}
+
+/**
+ * try_offline_node
+ * @nid: the node ID
+ *
+ * Offline a node if all memory sections and cpus of the node are removed.
+ *
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations before this call.
+ */
+void try_offline_node(int nid)
+{
+	int rc;
+
+	/*
+	 * If the node still spans pages (especially ZONE_DEVICE), don't
+	 * offline it. A node spans memory after move_pfn_range_to_zone(),
+	 * e.g., after the memory block was onlined.
+	 */
+	if (node_spanned_pages(nid))
+		return;
+
+	/*
+	 * Especially offline memory blocks might not be spanned by the
+	 * node. They will get spanned by the node once they get onlined.
+	 * However, they link to the node in sysfs and can get onlined later.
+	 */
+	rc = for_each_memory_block(&nid, check_no_memblock_for_node_cb);
+	if (rc)
+		return;
+
+	if (check_cpu_on_node(nid))
+		return;
+
+	/*
+	 * all memory/cpu of this node are removed, we can offline this
+	 * node now.
+	 */
+	node_set_offline(nid);
+	unregister_one_node(nid);
+}
+EXPORT_SYMBOL(try_offline_node);
+
+static int __ref try_remove_memory(u64 start, u64 size)
+{
+	struct vmem_altmap mhp_altmap = {};
+	struct vmem_altmap *altmap = NULL;
+	unsigned long nr_vmemmap_pages;
+	int rc = 0, nid = NUMA_NO_NODE;
+
+	BUG_ON(check_hotplug_memory_range(start, size));
+
+	/*
+	 * All memory blocks must be offlined before removing memory.  Check
+	 * whether all memory blocks in question are offline and return error
+	 * if this is not the case.
+	 *
+	 * While at it, determine the nid. Note that if we'd have mixed nodes,
+	 * we'd only try to offline the last determined one -- which is good
+	 * enough for the cases we care about.
+	 */
+	rc = walk_memory_blocks(start, size, &nid, check_memblock_offlined_cb);
+	if (rc)
+		return rc;
+
+	/*
+	 * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in
+	 * the same granularity it was added - a single memory block.
+	 */
+	if (mhp_memmap_on_memory()) {
+		nr_vmemmap_pages = walk_memory_blocks(start, size, NULL,
+						      get_nr_vmemmap_pages_cb);
+		if (nr_vmemmap_pages) {
+			if (size != memory_block_size_bytes()) {
+				pr_warn("Refuse to remove %#llx - %#llx,"
+					"wrong granularity\n",
+					start, start + size);
+				return -EINVAL;
+			}
+
+			/*
+			 * Let remove_pmd_table->free_hugepage_table do the
+			 * right thing if we used vmem_altmap when hot-adding
+			 * the range.
+			 */
+			mhp_altmap.alloc = nr_vmemmap_pages;
+			altmap = &mhp_altmap;
+		}
+	}
+
+	/* remove memmap entry */
+	firmware_map_remove(start, start + size, "System RAM");
+
+	/*
+	 * Memory block device removal under the device_hotplug_lock is
+	 * a barrier against racing online attempts.
+	 */
+	remove_memory_block_devices(start, size);
+
+	mem_hotplug_begin();
+
+	arch_remove_memory(start, size, altmap);
+
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
+		memblock_phys_free(start, size);
+		memblock_remove(start, size);
+	}
+
+	release_mem_region_adjustable(start, size);
+
+	if (nid != NUMA_NO_NODE)
+		try_offline_node(nid);
+
+	mem_hotplug_done();
+	return 0;
+}
+
+/**
+ * __remove_memory - Remove memory if every memory block is offline
+ * @start: physical address of the region to remove
+ * @size: size of the region to remove
+ *
+ * NOTE: The caller must call lock_device_hotplug() to serialize hotplug
+ * and online/offline operations before this call, as required by
+ * try_offline_node().
+ */
+void __remove_memory(u64 start, u64 size)
+{
+
+	/*
+	 * trigger BUG() if some memory is not offlined prior to calling this
+	 * function
+	 */
+	if (try_remove_memory(start, size))
+		BUG();
+}
+
+/*
+ * Remove memory if every memory block is offline, otherwise return -EBUSY is
+ * some memory is not offline
+ */
+int remove_memory(u64 start, u64 size)
+{
+	int rc;
+
+	lock_device_hotplug();
+	rc = try_remove_memory(start, size);
+	unlock_device_hotplug();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(remove_memory);
+
+static int try_offline_memory_block(struct memory_block *mem, void *arg)
+{
+	uint8_t online_type = MMOP_ONLINE_KERNEL;
+	uint8_t **online_types = arg;
+	struct page *page;
+	int rc;
+
+	/*
+	 * Sense the online_type via the zone of the memory block. Offlining
+	 * with multiple zones within one memory block will be rejected
+	 * by offlining code ... so we don't care about that.
+	 */
+	page = pfn_to_online_page(section_nr_to_pfn(mem->start_section_nr));
+	if (page && zone_idx(page_zone(page)) == ZONE_MOVABLE)
+		online_type = MMOP_ONLINE_MOVABLE;
+
+	rc = device_offline(&mem->dev);
+	/*
+	 * Default is MMOP_OFFLINE - change it only if offlining succeeded,
+	 * so try_reonline_memory_block() can do the right thing.
+	 */
+	if (!rc)
+		**online_types = online_type;
+
+	(*online_types)++;
+	/* Ignore if already offline. */
+	return rc < 0 ? rc : 0;
+}
+
+static int try_reonline_memory_block(struct memory_block *mem, void *arg)
+{
+	uint8_t **online_types = arg;
+	int rc;
+
+	if (**online_types != MMOP_OFFLINE) {
+		mem->online_type = **online_types;
+		rc = device_online(&mem->dev);
+		if (rc < 0)
+			pr_warn("%s: Failed to re-online memory: %d",
+				__func__, rc);
+	}
+
+	/* Continue processing all remaining memory blocks. */
+	(*online_types)++;
+	return 0;
+}
+
+/*
+ * Try to offline and remove memory. Might take a long time to finish in case
+ * memory is still in use. Primarily useful for memory devices that logically
+ * unplugged all memory (so it's no longer in use) and want to offline + remove
+ * that memory.
+ */
+int offline_and_remove_memory(u64 start, u64 size)
+{
+	const unsigned long mb_count = size / memory_block_size_bytes();
+	uint8_t *online_types, *tmp;
+	int rc;
+
+	if (!IS_ALIGNED(start, memory_block_size_bytes()) ||
+	    !IS_ALIGNED(size, memory_block_size_bytes()) || !size)
+		return -EINVAL;
+
+	/*
+	 * We'll remember the old online type of each memory block, so we can
+	 * try to revert whatever we did when offlining one memory block fails
+	 * after offlining some others succeeded.
+	 */
+	online_types = kmalloc_array(mb_count, sizeof(*online_types),
+				     GFP_KERNEL);
+	if (!online_types)
+		return -ENOMEM;
+	/*
+	 * Initialize all states to MMOP_OFFLINE, so when we abort processing in
+	 * try_offline_memory_block(), we'll skip all unprocessed blocks in
+	 * try_reonline_memory_block().
+	 */
+	memset(online_types, MMOP_OFFLINE, mb_count);
+
+	lock_device_hotplug();
+
+	tmp = online_types;
+	rc = walk_memory_blocks(start, size, &tmp, try_offline_memory_block);
+
+	/*
+	 * In case we succeeded to offline all memory, remove it.
+	 * This cannot fail as it cannot get onlined in the meantime.
+	 */
+	if (!rc) {
+		rc = try_remove_memory(start, size);
+		if (rc)
+			pr_err("%s: Failed to remove memory: %d", __func__, rc);
+	}
+
+	/*
+	 * Rollback what we did. While memory onlining might theoretically fail
+	 * (nacked by a notifier), it barely ever happens.
+	 */
+	if (rc) {
+		tmp = online_types;
+		walk_memory_blocks(start, size, &tmp,
+				   try_reonline_memory_block);
+	}
+	unlock_device_hotplug();
+
+	kfree(online_types);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(offline_and_remove_memory);
+#endif /* CONFIG_MEMORY_HOTREMOVE */