Adding upstream version 5.10.209.upstream/5.10.209upstream

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

1 files changed, 1906 insertions, 0 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
new file mode 100644
index 000000000..553b0705d
--- /dev/null
+++ b/mm/memory_hotplug.c
@@ -0,0 +1,1906 @@
+// 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/highmem.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 <asm/tlbflush.h>
+
+#include "internal.h"
+#include "shuffle.h"
+
+/*
+ * 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 memhp_default_online_type = MMOP_OFFLINE;
+#else
+int memhp_default_online_type = MMOP_ONLINE;
+#endif
+
+static int __init setup_memhp_default_state(char *str)
+{
+	const int online_type = memhp_online_type_from_str(str);
+
+	if (online_type >= 0)
+		memhp_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;
+
+	/*
+	 * 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);
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
+void get_page_bootmem(unsigned long info,  struct page *page,
+		      unsigned long type)
+{
+	page->freelist = (void *)type;
+	SetPagePrivate(page);
+	set_page_private(page, info);
+	page_ref_inc(page);
+}
+
+void put_page_bootmem(struct page *page)
+{
+	unsigned long type;
+
+	type = (unsigned long) page->freelist;
+	BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
+	       type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE);
+
+	if (page_ref_dec_return(page) == 1) {
+		page->freelist = NULL;
+		ClearPagePrivate(page);
+		set_page_private(page, 0);
+		INIT_LIST_HEAD(&page->lru);
+		free_reserved_page(page);
+	}
+}
+
+#ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
+#ifndef CONFIG_SPARSEMEM_VMEMMAP
+static void register_page_bootmem_info_section(unsigned long start_pfn)
+{
+	unsigned long mapsize, section_nr, i;
+	struct mem_section *ms;
+	struct page *page, *memmap;
+	struct mem_section_usage *usage;
+
+	section_nr = pfn_to_section_nr(start_pfn);
+	ms = __nr_to_section(section_nr);
+
+	/* Get section's memmap address */
+	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+
+	/*
+	 * Get page for the memmap's phys address
+	 * XXX: need more consideration for sparse_vmemmap...
+	 */
+	page = virt_to_page(memmap);
+	mapsize = sizeof(struct page) * PAGES_PER_SECTION;
+	mapsize = PAGE_ALIGN(mapsize) >> PAGE_SHIFT;
+
+	/* remember memmap's page */
+	for (i = 0; i < mapsize; i++, page++)
+		get_page_bootmem(section_nr, page, SECTION_INFO);
+
+	usage = ms->usage;
+	page = virt_to_page(usage);
+
+	mapsize = PAGE_ALIGN(mem_section_usage_size()) >> PAGE_SHIFT;
+
+	for (i = 0; i < mapsize; i++, page++)
+		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
+
+}
+#else /* CONFIG_SPARSEMEM_VMEMMAP */
+static void register_page_bootmem_info_section(unsigned long start_pfn)
+{
+	unsigned long mapsize, section_nr, i;
+	struct mem_section *ms;
+	struct page *page, *memmap;
+	struct mem_section_usage *usage;
+
+	section_nr = pfn_to_section_nr(start_pfn);
+	ms = __nr_to_section(section_nr);
+
+	memmap = sparse_decode_mem_map(ms->section_mem_map, section_nr);
+
+	register_page_bootmem_memmap(section_nr, memmap, PAGES_PER_SECTION);
+
+	usage = ms->usage;
+	page = virt_to_page(usage);
+
+	mapsize = PAGE_ALIGN(mem_section_usage_size()) >> PAGE_SHIFT;
+
+	for (i = 0; i < mapsize; i++, page++)
+		get_page_bootmem(section_nr, page, MIX_SECTION_INFO);
+}
+#endif /* !CONFIG_SPARSEMEM_VMEMMAP */
+
+void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
+{
+	unsigned long i, pfn, end_pfn, nr_pages;
+	int node = pgdat->node_id;
+	struct page *page;
+
+	nr_pages = PAGE_ALIGN(sizeof(struct pglist_data)) >> PAGE_SHIFT;
+	page = virt_to_page(pgdat);
+
+	for (i = 0; i < nr_pages; i++, page++)
+		get_page_bootmem(node, page, NODE_INFO);
+
+	pfn = pgdat->node_start_pfn;
+	end_pfn = pgdat_end_pfn(pgdat);
+
+	/* register section info */
+	for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		/*
+		 * Some platforms can assign the same pfn to multiple nodes - on
+		 * node0 as well as nodeN.  To avoid registering a pfn against
+		 * multiple nodes we check that this pfn does not already
+		 * reside in some other nodes.
+		 */
+		if (pfn_valid(pfn) && (early_pfn_to_nid(pfn) == node))
+			register_page_bootmem_info_section(pfn);
+	}
+}
+#endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
+
+static int check_pfn_span(unsigned long pfn, unsigned long nr_pages,
+		const char *reason)
+{
+	/*
+	 * 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, min_align)
+			|| !IS_ALIGNED(nr_pages, min_align)) {
+		WARN(1, "Misaligned __%s_pages start: %#lx end: #%lx\n",
+				reason, pfn, pfn + nr_pages - 1);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+static int check_hotplug_memory_addressable(unsigned long pfn,
+					    unsigned long nr_pages)
+{
+	const u64 max_addr = PFN_PHYS(pfn + nr_pages) - 1;
+
+	if (max_addr >> MAX_PHYSMEM_BITS) {
+		const u64 max_allowed = (1ull << (MAX_PHYSMEM_BITS + 1)) - 1;
+		WARN(1,
+		     "Hotplugged memory exceeds maximum addressable address, range=%#llx-%#llx, maximum=%#llx\n",
+		     (u64)PFN_PHYS(pfn), max_addr, max_allowed);
+		return -E2BIG;
+	}
+
+	return 0;
+}
+
+/*
+ * Reasonably generic function for adding memory.  It is
+ * expected that archs that support memory hotplug will
+ * call this function after deciding the zone to which to
+ * add the new pages.
+ */
+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(!params->pgprot.pgprot))
+		return -EINVAL;
+
+	err = check_hotplug_memory_addressable(pfn, nr_pages);
+	if (err)
+		return err;
+
+	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;
+	}
+
+	err = check_pfn_span(pfn, nr_pages, "add");
+	if (err)
+		return err;
+
+	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);
+		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);
+
+	zone_span_writelock(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;
+		}
+	}
+	zone_span_writeunlock(zone);
+}
+
+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 zone_end_pfn = zone->zone_start_pfn +
+					     zone->spanned_pages;
+
+		/* 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 = zone_end_pfn;
+			continue;
+		}
+
+		if (zone_end_pfn > node_end_pfn)
+			node_end_pfn = zone_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, flags;
+
+	/* 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);
+	}
+
+#ifdef CONFIG_ZONE_DEVICE
+	/*
+	 * 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_idx(zone) == ZONE_DEVICE)
+		return;
+#endif
+
+	clear_zone_contiguous(zone);
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	shrink_zone_span(zone, start_pfn, start_pfn + nr_pages);
+	update_pgdat_span(pgdat);
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
+	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, "remove"))
+		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.
+	 */
+	if (debug_pagealloc_enabled_static())
+		kernel_map_pages(page, 1 << order, 1);
+	__free_pages_core(page, order);
+	totalram_pages_add(1UL << order);
+#ifdef CONFIG_HIGHMEM
+	if (PageHighMem(page))
+		totalhigh_pages_add(1UL << order);
+#endif
+}
+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").
+	 */
+	for (pfn = start_pfn; pfn < end_pfn; pfn += MAX_ORDER_NR_PAGES)
+		(*online_page_callback)(pfn_to_page(pfn), MAX_ORDER - 1);
+
+	/* 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;
+	arg->status_change_nid_high = 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;
+#ifdef CONFIG_HIGHMEM
+	if (zone_idx(zone) <= ZONE_HIGHMEM && !node_state(nid, N_HIGH_MEMORY))
+		arg->status_change_nid_high = nid;
+#endif
+}
+
+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_high >= 0)
+		node_set_state(node, N_HIGH_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;
+
+}
+/*
+ * 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;
+	unsigned long flags;
+
+	clear_zone_contiguous(zone);
+
+	/* TODO Huh pgdat is irqsave while zone is not. It used to be like that before */
+	pgdat_resize_lock(pgdat, &flags);
+	zone_span_writelock(zone);
+	if (zone_is_empty(zone))
+		init_currently_empty_zone(zone, start_pfn, nr_pages);
+	resize_zone_range(zone, start_pfn, nr_pages);
+	zone_span_writeunlock(zone);
+	resize_pgdat_range(pgdat, start_pfn, nr_pages);
+	pgdat_resize_unlock(pgdat, &flags);
+
+	/*
+	 * 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_zone(nr_pages, nid, zone_idx(zone), start_pfn, 0,
+			 MEMINIT_HOTPLUG, altmap, migratetype);
+
+	set_zone_contiguous(zone);
+}
+
+/*
+ * 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];
+}
+
+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,
+		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];
+
+	return default_zone_for_pfn(nid, start_pfn, nr_pages);
+}
+
+int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
+		       int online_type, int nid)
+{
+	unsigned long flags;
+	struct zone *zone;
+	int need_zonelists_rebuild = 0;
+	int ret;
+	struct memory_notify arg;
+
+	/* We can only online full sections (e.g., SECTION_IS_ONLINE) */
+	if (WARN_ON_ONCE(!nr_pages ||
+			 !IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION)))
+		return -EINVAL;
+
+	mem_hotplug_begin();
+
+	/* associate pfn range with the zone */
+	zone = zone_for_pfn_range(online_type, nid, pfn, nr_pages);
+	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);
+	zone->present_pages += nr_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	zone->zone_pgdat->node_present_pages += nr_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
+	node_states_set_node(nid, &arg);
+	if (need_zonelists_rebuild)
+		build_all_zonelists(NULL);
+	zone_pcp_update(zone);
+
+	/* 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);
+
+	init_per_zone_wmark_min();
+
+	kswapd_run(nid);
+	kcompactd_run(nid);
+
+	writeback_set_ratelimit();
+
+	memory_notify(MEM_ONLINE, &arg);
+	mem_hotplug_done();
+	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);
+	mem_hotplug_done();
+	return ret;
+}
+#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
+
+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_new_pgdat(int nid)
+{
+	struct pglist_data *pgdat;
+
+	pgdat = NODE_DATA(nid);
+	if (!pgdat) {
+		pgdat = arch_alloc_nodedata(nid);
+		if (!pgdat)
+			return NULL;
+
+		pgdat->per_cpu_nodestats =
+			alloc_percpu(struct per_cpu_nodestat);
+		arch_refresh_nodedata(nid, pgdat);
+	} else {
+		int cpu;
+		/*
+		 * Reset the nr_zones, order and highest_zoneidx before reuse.
+		 * Note that kswapd will init kswapd_highest_zoneidx properly
+		 * when it starts in the near future.
+		 */
+		pgdat->nr_zones = 0;
+		pgdat->kswapd_order = 0;
+		pgdat->kswapd_highest_zoneidx = 0;
+		for_each_online_cpu(cpu) {
+			struct per_cpu_nodestat *p;
+
+			p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
+			memset(p, 0, sizeof(*p));
+		}
+	}
+
+	/* we can use NODE_DATA(nid) from here */
+	pgdat->node_id = nid;
+	pgdat->node_start_pfn = 0;
+
+	/* init node's zones as empty zones, we don't have any present pages.*/
+	free_area_init_core_hotplug(nid);
+
+	/*
+	 * 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().
+	 */
+	reset_node_managed_pages(pgdat);
+	reset_node_present_pages(pgdat);
+
+	return pgdat;
+}
+
+static void rollback_node_hotadd(int nid)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+
+	arch_refresh_nodedata(nid, NULL);
+	free_percpu(pgdat->per_cpu_nodestats);
+	arch_free_nodedata(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_new_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 = memhp_default_online_type;
+	return device_online(&mem->dev);
+}
+
+/*
+ * 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) };
+	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 (!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))
+		memblock_add_node(start, size, nid);
+
+	ret = __try_online_node(nid, false);
+	if (ret < 0)
+		goto error;
+	new_node = ret;
+
+	/* 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);
+	if (ret) {
+		arch_remove_memory(nid, start, size, NULL);
+		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);
+	}
+
+	/* link memory sections under this node.*/
+	link_mem_sections(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 & MEMHP_MERGE_RESOURCE)
+		merge_system_ram_resource(res);
+
+	/* online pages if requested */
+	if (memhp_default_online_type != MMOP_OFFLINE)
+		walk_memory_blocks(start, size, NULL, online_memory_block);
+
+	return ret;
+error:
+	/* rollback pgdat allocation and others */
+	if (new_node)
+		rollback_node_hotadd(nid);
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
+		memblock_remove(start, size);
+	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);
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * Confirm all pages in a range [start, end) belong to the same zone (skipping
+ * memory holes). When true, return the zone.
+ */
+struct zone *test_pages_in_a_zone(unsigned long start_pfn,
+				  unsigned long end_pfn)
+{
+	unsigned long pfn, sec_end_pfn;
+	struct zone *zone = NULL;
+	struct page *page;
+	int i;
+	for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
+	     pfn < end_pfn;
+	     pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
+		/* Make sure the memory section is present first */
+		if (!present_section_nr(pfn_to_section_nr(pfn)))
+			continue;
+		for (; pfn < sec_end_pfn && pfn < end_pfn;
+		     pfn += MAX_ORDER_NR_PAGES) {
+			i = 0;
+			/* This is just a CONFIG_HOLES_IN_ZONE check.*/
+			while ((i < MAX_ORDER_NR_PAGES) &&
+				!pfn_valid_within(pfn + i))
+				i++;
+			if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn)
+				continue;
+			/* Check if we got outside of the zone */
+			if (zone && !zone_spans_pfn(zone, pfn + i))
+				return NULL;
+			page = pfn_to_page(pfn + i);
+			if (zone && page_zone(page) != zone)
+				return NULL;
+			zone = page_zone(page);
+		}
+	}
+
+	return zone;
+}
+
+/*
+ * 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);
+		if (page_huge_active(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++) {
+		if (!pfn_valid(pfn))
+			continue;
+		page = pfn_to_page(pfn);
+		head = compound_head(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(PageLRU(page)))
+				isolate_lru_page(page);
+			if (page_mapped(page))
+				try_to_unmap(page, 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);
+		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;
+	arg->status_change_nid_high = 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);
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * node_states[N_HIGH_MEMORY] contains nodes which
+	 * have normal memory or high memory.
+	 * Here we add the present_pages belonging to ZONE_HIGHMEM.
+	 * If the zone is within the range of [0..ZONE_HIGHMEM), and
+	 * we determine that the zones in that range become empty,
+	 * we need to clear the node for N_HIGH_MEMORY.
+	 */
+	present_pages += pgdat->node_zones[ZONE_HIGHMEM].present_pages;
+	if (zone_idx(zone) <= ZONE_HIGHMEM && nr_pages >= present_pages)
+		arg->status_change_nid_high = zone_to_nid(zone);
+#endif
+
+	/*
+	 * We have accounted the pages from [0..ZONE_NORMAL), and
+	 * in case of CONFIG_HIGHMEM the pages from ZONE_HIGHMEM
+	 * as well.
+	 * 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_high >= 0)
+		node_clear_state(node, N_HIGH_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;
+}
+
+int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
+{
+	const unsigned long end_pfn = start_pfn + nr_pages;
+	unsigned long pfn, system_ram_pages = 0;
+	unsigned long flags;
+	struct zone *zone;
+	struct memory_notify arg;
+	int ret, node;
+	char *reason;
+
+	/* We can only offline full sections (e.g., SECTION_IS_ONLINE) */
+	if (WARN_ON_ONCE(!nr_pages ||
+			 !IS_ALIGNED(start_pfn | nr_pages, PAGES_PER_SECTION)))
+		return -EINVAL;
+
+	mem_hotplug_begin();
+
+	/*
+	 * 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;
+	}
+
+	/* This makes hotplug much easier...and readable.
+	   we assume this for now. .*/
+	zone = test_pages_in_a_zone(start_pfn, end_pfn);
+	if (!zone) {
+		ret = -EINVAL;
+		reason = "multizone range";
+		goto failed_removal;
+	}
+	node = zone_to_nid(zone);
+
+	/* set above range as isolated */
+	ret = start_isolate_page_range(start_pfn, end_pfn,
+				       MIGRATE_MOVABLE,
+				       MEMORY_OFFLINE | REPORT_FAILURE);
+	if (ret) {
+		reason = "failure to isolate range";
+		goto failed_removal;
+	}
+
+	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();
+			lru_add_drain_all();
+
+			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;
+		}
+
+		/*
+		 * per-cpu pages are drained in start_isolate_page_range, but if
+		 * there are still pages that are not free, make sure that we
+		 * drain again, because when we isolated range we might
+		 * have raced with another thread that was adding pages to pcp
+		 * list.
+		 *
+		 * Forward progress should be still guaranteed because
+		 * pages on the pcp list can only belong to MOVABLE_ZONE
+		 * because has_unmovable_pages explicitly checks for
+		 * PageBuddy on freed pages on other zones.
+		 */
+		ret = test_pages_isolated(start_pfn, end_pfn, MEMORY_OFFLINE);
+		if (ret)
+			drain_all_pages(zone);
+	} while (ret);
+
+	/* Mark all sections offline and remove free pages from the buddy. */
+	__offline_isolated_pages(start_pfn, end_pfn);
+	pr_info("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);
+
+	/* removal success */
+	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
+	zone->present_pages -= nr_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	zone->zone_pgdat->node_present_pages -= nr_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
+	init_per_zone_wmark_min();
+
+	if (!populated_zone(zone)) {
+		zone_pcp_reset(zone);
+		build_all_zonelists(NULL);
+	} else
+		zone_pcp_update(zone);
+
+	node_states_clear_node(node, &arg);
+	if (arg.status_change_nid >= 0) {
+		kswapd_stop(node);
+		kcompactd_stop(node);
+	}
+
+	writeback_set_ratelimit();
+
+	memory_notify(MEM_OFFLINE, &arg);
+	remove_pfn_range_from_zone(zone, start_pfn, nr_pages);
+	mem_hotplug_done();
+	return 0;
+
+failed_removal_isolated:
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	memory_notify(MEM_CANCEL_OFFLINE, &arg);
+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);
+	/* pushback to free area */
+	mem_hotplug_done();
+	return ret;
+}
+
+static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
+{
+	int ret = !is_memblock_offlined(mem);
+
+	if (unlikely(ret)) {
+		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 check_cpu_on_node(pg_data_t *pgdat)
+{
+	int cpu;
+
+	for_each_present_cpu(cpu) {
+		if (cpu_to_node(cpu) == pgdat->node_id)
+			/*
+			 * 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)
+{
+	pg_data_t *pgdat = NODE_DATA(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 (pgdat->node_spanned_pages)
+		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(pgdat))
+		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(int nid, u64 start, u64 size)
+{
+	int rc = 0;
+
+	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.
+	 */
+	rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
+	if (rc)
+		return rc;
+
+	/* 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(nid, start, size, NULL);
+
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
+		memblock_free(start, size);
+		memblock_remove(start, size);
+	}
+
+	release_mem_region_adjustable(start, size);
+
+	try_offline_node(nid);
+
+	mem_hotplug_done();
+	return 0;
+}
+
+/**
+ * remove_memory
+ * @nid: the node ID
+ * @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(int nid, u64 start, u64 size)
+{
+
+	/*
+	 * trigger BUG() if some memory is not offlined prior to calling this
+	 * function
+	 */
+	if (try_remove_memory(nid, start, size))
+		BUG();
+}
+
+/*
+ * Remove memory if every memory block is offline, otherwise return -EBUSY is
+ * some memory is not offline
+ */
+int remove_memory(int nid, u64 start, u64 size)
+{
+	int rc;
+
+	lock_device_hotplug();
+	rc  = try_remove_memory(nid, 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(int nid, 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(nid, 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 */