Adding upstream version 4.19.249.upstream/4.19.249

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

1 files changed, 1944 insertions, 0 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
new file mode 100644
index 000000000..20f079c81
--- /dev/null
+++ b/mm/memory_hotplug.c
@@ -0,0 +1,1944 @@
+/*
+ *  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/bootmem.h>
+#include <linux/compaction.h>
+#include <linux/rmap.h>
+
+#include <asm/tlbflush.h>
+
+#include "internal.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 void generic_online_page(struct page *page);
+
+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
+bool memhp_auto_online;
+#else
+bool memhp_auto_online = true;
+#endif
+EXPORT_SYMBOL_GPL(memhp_auto_online);
+
+static int __init setup_memhp_default_state(char *str)
+{
+	if (!strcmp(str, "online"))
+		memhp_auto_online = true;
+	else if (!strcmp(str, "offline"))
+		memhp_auto_online = false;
+
+	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();
+}
+
+/* add this memory to iomem resource */
+static struct resource *register_memory_resource(u64 start, u64 size)
+{
+	struct resource *res, *conflict;
+	res = kzalloc(sizeof(struct resource), GFP_KERNEL);
+	if (!res)
+		return ERR_PTR(-ENOMEM);
+
+	res->name = "System RAM";
+	res->start = start;
+	res->end = start + size - 1;
+	res->flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
+	conflict =  request_resource_conflict(&iomem_resource, res);
+	if (conflict) {
+		if (conflict->desc == IORES_DESC_DEVICE_PRIVATE_MEMORY) {
+			pr_debug("Device unaddressable memory block "
+				 "memory hotplug at %#010llx !\n",
+				 (unsigned long long)start);
+		}
+		pr_debug("System RAM resource %pR cannot be added\n", res);
+		kfree(res);
+		return ERR_PTR(-EEXIST);
+	}
+	return res;
+}
+
+static void release_memory_resource(struct resource *res)
+{
+	if (!res)
+		return;
+	release_resource(res);
+	kfree(res);
+	return;
+}
+
+#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 *usemap, mapsize, section_nr, i;
+	struct mem_section *ms;
+	struct page *page, *memmap;
+
+	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);
+
+	usemap = ms->pageblock_flags;
+	page = virt_to_page(usemap);
+
+	mapsize = PAGE_ALIGN(usemap_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 *usemap, mapsize, section_nr, i;
+	struct mem_section *ms;
+	struct page *page, *memmap;
+
+	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);
+
+	usemap = ms->pageblock_flags;
+	page = virt_to_page(usemap);
+
+	mapsize = PAGE_ALIGN(usemap_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 __meminit __add_section(int nid, unsigned long phys_start_pfn,
+		struct vmem_altmap *altmap, bool want_memblock)
+{
+	int ret;
+
+	if (pfn_valid(phys_start_pfn))
+		return -EEXIST;
+
+	ret = sparse_add_one_section(nid, phys_start_pfn, altmap);
+	return ret < 0 ? ret : 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 phys_start_pfn,
+		unsigned long nr_pages, struct vmem_altmap *altmap,
+		bool want_memblock)
+{
+	unsigned long i;
+	int err = 0;
+	int start_sec, end_sec;
+
+	/* during initialize mem_map, align hot-added range to section */
+	start_sec = pfn_to_section_nr(phys_start_pfn);
+	end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
+
+	if (altmap) {
+		/*
+		 * Validate altmap is within bounds of the total request
+		 */
+		if (altmap->base_pfn != phys_start_pfn
+				|| vmem_altmap_offset(altmap) > nr_pages) {
+			pr_warn_once("memory add fail, invalid altmap\n");
+			err = -EINVAL;
+			goto out;
+		}
+		altmap->alloc = 0;
+	}
+
+	for (i = start_sec; i <= end_sec; i++) {
+		err = __add_section(nid, section_nr_to_pfn(i), altmap,
+				want_memblock);
+
+		/*
+		 * EEXIST is finally dealt with by ioresource collision
+		 * check. see add_memory() => register_memory_resource()
+		 * Warning will be printed if there is collision.
+		 */
+		if (err && (err != -EEXIST))
+			break;
+		err = 0;
+		cond_resched();
+	}
+	vmemmap_populate_print_last();
+out:
+	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_SECTION) {
+		if (unlikely(!pfn_to_online_page(start_pfn)))
+			continue;
+
+		if (unlikely(pfn_to_nid(start_pfn) != nid))
+			continue;
+
+		if (zone && 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_SECTION) {
+		if (unlikely(!pfn_to_online_page(pfn)))
+			continue;
+
+		if (unlikely(pfn_to_nid(pfn) != nid))
+			continue;
+
+		if (zone && 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 zone_start_pfn = zone->zone_start_pfn;
+	unsigned long z = zone_end_pfn(zone); /* zone_end_pfn namespace clash */
+	unsigned long zone_end_pfn = z;
+	unsigned long pfn;
+	int nid = zone_to_nid(zone);
+
+	zone_span_writelock(zone);
+	if (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);
+		if (pfn) {
+			zone->zone_start_pfn = pfn;
+			zone->spanned_pages = zone_end_pfn - pfn;
+		}
+	} else if (zone_end_pfn == 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_start_pfn,
+					       start_pfn);
+		if (pfn)
+			zone->spanned_pages = pfn - zone_start_pfn + 1;
+	}
+
+	/*
+	 * The section is not biggest or smallest mem_section in the zone, it
+	 * only creates a hole in the zone. So in this case, we need not
+	 * change the zone. But perhaps, the zone has only hole data. Thus
+	 * it check the zone has only hole or not.
+	 */
+	pfn = zone_start_pfn;
+	for (; pfn < zone_end_pfn; pfn += PAGES_PER_SECTION) {
+		if (unlikely(!pfn_to_online_page(pfn)))
+			continue;
+
+		if (page_zone(pfn_to_page(pfn)) != zone)
+			continue;
+
+		 /* If the section is current section, it continues the loop */
+		if (start_pfn == pfn)
+			continue;
+
+		/* If we find valid section, we have nothing to do */
+		zone_span_writeunlock(zone);
+		return;
+	}
+
+	/* The zone has no valid section */
+	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)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	unsigned long flags;
+
+#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(struct mem_section *ms, unsigned long map_offset,
+			     struct vmem_altmap *altmap)
+{
+	unsigned long start_pfn;
+	int scn_nr;
+
+	if (WARN_ON_ONCE(!valid_section(ms)))
+		return;
+
+	scn_nr = __section_nr(ms);
+	start_pfn = section_nr_to_pfn((unsigned long)scn_nr);
+
+	sparse_remove_one_section(ms, map_offset, altmap);
+}
+
+/**
+ * __remove_pages() - remove sections of pages
+ * @phys_start_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 phys_start_pfn, unsigned long nr_pages,
+		    struct vmem_altmap *altmap)
+{
+	unsigned long i;
+	unsigned long map_offset = 0;
+	int sections_to_remove;
+
+	if (altmap)
+		map_offset = vmem_altmap_offset(altmap);
+
+	/*
+	 * We can only remove entire sections
+	 */
+	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
+	BUG_ON(nr_pages % PAGES_PER_SECTION);
+
+	sections_to_remove = nr_pages / PAGES_PER_SECTION;
+	for (i = 0; i < sections_to_remove; i++) {
+		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
+
+		cond_resched();
+		__remove_section(__pfn_to_section(pfn), 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 __online_page_set_limits(struct page *page)
+{
+}
+EXPORT_SYMBOL_GPL(__online_page_set_limits);
+
+void __online_page_increment_counters(struct page *page)
+{
+	adjust_managed_page_count(page, 1);
+}
+EXPORT_SYMBOL_GPL(__online_page_increment_counters);
+
+void __online_page_free(struct page *page)
+{
+	__free_reserved_page(page);
+}
+EXPORT_SYMBOL_GPL(__online_page_free);
+
+static void generic_online_page(struct page *page)
+{
+	__online_page_set_limits(page);
+	__online_page_increment_counters(page);
+	__online_page_free(page);
+}
+
+static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
+			void *arg)
+{
+	unsigned long i;
+	unsigned long onlined_pages = *(unsigned long *)arg;
+	struct page *page;
+
+	if (PageReserved(pfn_to_page(start_pfn)))
+		for (i = 0; i < nr_pages; i++) {
+			page = pfn_to_page(start_pfn + i);
+			(*online_page_callback)(page);
+			onlined_pages++;
+		}
+
+	online_mem_sections(start_pfn, start_pfn + nr_pages);
+
+	*(unsigned long *)arg = onlined_pages;
+	return 0;
+}
+
+/* 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);
+	enum zone_type zone_last = ZONE_NORMAL;
+
+	/*
+	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_NORMAL,
+	 * set zone_last to ZONE_NORMAL.
+	 *
+	 * If we don't have HIGHMEM nor movable node,
+	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
+	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
+	 */
+	if (N_MEMORY == N_NORMAL_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	/*
+	 * if the memory to be online is in a zone of 0...zone_last, and
+	 * the zones of 0...zone_last don't have memory before online, we will
+	 * need to set the node to node_states[N_NORMAL_MEMORY] after
+	 * the memory is online.
+	 */
+	if (zone_idx(zone) <= zone_last && !node_state(nid, N_NORMAL_MEMORY))
+		arg->status_change_nid_normal = nid;
+	else
+		arg->status_change_nid_normal = -1;
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * If we have movable node, node_states[N_HIGH_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
+	 * set zone_last to ZONE_HIGHMEM.
+	 *
+	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_MOVABLE,
+	 * set zone_last to ZONE_MOVABLE.
+	 */
+	zone_last = ZONE_HIGHMEM;
+	if (N_MEMORY == N_HIGH_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	if (zone_idx(zone) <= zone_last && !node_state(nid, N_HIGH_MEMORY))
+		arg->status_change_nid_high = nid;
+	else
+		arg->status_change_nid_high = -1;
+#else
+	arg->status_change_nid_high = arg->status_change_nid_normal;
+#endif
+
+	/*
+	 * if the node don't have memory befor online, we will need to
+	 * set the node to node_states[N_MEMORY] after the memory
+	 * is online.
+	 */
+	if (!node_state(nid, N_MEMORY))
+		arg->status_change_nid = nid;
+	else
+		arg->status_change_nid = -1;
+}
+
+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);
+
+	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;
+}
+
+void __ref move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
+		unsigned long nr_pages, struct vmem_altmap *altmap)
+{
+	struct pglist_data *pgdat = zone->zone_pgdat;
+	int nid = pgdat->node_id;
+	unsigned long flags;
+
+	if (zone_is_empty(zone))
+		init_currently_empty_zone(zone, start_pfn, nr_pages);
+
+	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);
+	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,
+			 MEMINIT_HOTPLUG, altmap);
+
+	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);
+}
+
+/*
+ * Associates the given pfn range with the given node and the zone appropriate
+ * for the given online type.
+ */
+static struct zone * __meminit move_pfn_range(int online_type, int nid,
+		unsigned long start_pfn, unsigned long nr_pages)
+{
+	struct zone *zone;
+
+	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
+	move_pfn_range_to_zone(zone, start_pfn, nr_pages, NULL);
+	return zone;
+}
+
+int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
+{
+	unsigned long flags;
+	unsigned long onlined_pages = 0;
+	struct zone *zone;
+	int need_zonelists_rebuild = 0;
+	int nid;
+	int ret;
+	struct memory_notify arg;
+	struct memory_block *mem;
+
+	mem_hotplug_begin();
+
+	/*
+	 * We can't use pfn_to_nid() because nid might be stored in struct page
+	 * which is not yet initialized. Instead, we find nid from memory block.
+	 */
+	mem = find_memory_block(__pfn_to_section(pfn));
+	nid = mem->nid;
+	put_device(&mem->dev);
+
+	/* associate pfn range with the zone */
+	zone = move_pfn_range(online_type, nid, pfn, nr_pages);
+
+	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;
+
+	/*
+	 * 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);
+	}
+
+	ret = walk_system_ram_range(pfn, nr_pages, &onlined_pages,
+		online_pages_range);
+	if (ret) {
+		if (need_zonelists_rebuild)
+			zone_pcp_reset(zone);
+		goto failed_addition;
+	}
+
+	zone->present_pages += onlined_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	zone->zone_pgdat->node_present_pages += onlined_pages;
+	pgdat_resize_unlock(zone->zone_pgdat, &flags);
+
+	if (onlined_pages) {
+		node_states_set_node(nid, &arg);
+		if (need_zonelists_rebuild)
+			build_all_zonelists(NULL);
+		else
+			zone_pcp_update(zone);
+	}
+
+	init_per_zone_wmark_min();
+
+	if (onlined_pages) {
+		kswapd_run(nid);
+		kcompactd_run(nid);
+	}
+
+	vm_total_pages = nr_free_pagecache_pages();
+
+	writeback_set_ratelimit();
+
+	if (onlined_pages)
+		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, u64 start)
+{
+	struct pglist_data *pgdat;
+	unsigned long start_pfn = PFN_DOWN(start);
+
+	pgdat = NODE_DATA(nid);
+	if (!pgdat) {
+		pgdat = arch_alloc_nodedata(nid);
+		if (!pgdat)
+			return NULL;
+
+		arch_refresh_nodedata(nid, pgdat);
+	} else {
+		/*
+		 * Reset the nr_zones, order and classzone_idx before reuse.
+		 * Note that kswapd will init kswapd_classzone_idx properly
+		 * when it starts in the near future.
+		 */
+		pgdat->nr_zones = 0;
+		pgdat->kswapd_order = 0;
+		pgdat->kswapd_classzone_idx = 0;
+	}
+
+	/* we can use NODE_DATA(nid) from here */
+
+	pgdat->node_id = nid;
+	pgdat->node_start_pfn = start_pfn;
+
+	/* init node's zones as empty zones, we don't have any present pages.*/
+	free_area_init_core_hotplug(nid);
+	pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat);
+
+	/*
+	 * 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);
+	return;
+}
+
+
+/**
+ * try_online_node - online a node if offlined
+ * @nid: the node ID
+ * @start: start addr of the node
+ * @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, u64 start, bool set_node_online)
+{
+	pg_data_t *pgdat;
+	int ret = 1;
+
+	if (node_online(nid))
+		return 0;
+
+	pgdat = hotadd_new_pgdat(nid, start);
+	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, 0, true);
+	mem_hotplug_done();
+	return ret;
+}
+
+static int check_hotplug_memory_range(u64 start, u64 size)
+{
+	unsigned long block_sz = memory_block_size_bytes();
+	u64 block_nr_pages = block_sz >> PAGE_SHIFT;
+	u64 nr_pages = size >> PAGE_SHIFT;
+	u64 start_pfn = PFN_DOWN(start);
+
+	/* memory range must be block size aligned */
+	if (!nr_pages || !IS_ALIGNED(start_pfn, block_nr_pages) ||
+	    !IS_ALIGNED(nr_pages, block_nr_pages)) {
+		pr_err("Block size [%#lx] unaligned hotplug range: start %#llx, size %#llx",
+		       block_sz, start, size);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int online_memory_block(struct memory_block *mem, void *arg)
+{
+	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, bool online)
+{
+	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;
+
+	mem_hotplug_begin();
+
+	/*
+	 * Add new range to memblock so that when hotadd_new_pgdat() is called
+	 * to allocate new pgdat, get_pfn_range_for_nid() will be able to find
+	 * this new range and calculate total pages correctly.  The range will
+	 * be removed at hot-remove time.
+	 */
+	memblock_add_node(start, size, nid);
+
+	ret = __try_online_node(nid, start, false);
+	if (ret < 0)
+		goto error;
+	new_node = ret;
+
+	/* call arch's memory hotadd */
+	ret = arch_add_memory(nid, start, size, NULL, true);
+	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.*/
+	ret = link_mem_sections(nid, PFN_DOWN(start), PFN_UP(start + size - 1),
+				MEMINIT_HOTPLUG);
+	BUG_ON(ret);
+
+	/* create new memmap entry */
+	firmware_map_add_hotplug(start, start + size, "System RAM");
+
+	/* device_online() will take the lock when calling online_pages() */
+	mem_hotplug_done();
+
+	/* online pages if requested */
+	if (online)
+		walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
+				  NULL, online_memory_block);
+
+	return ret;
+error:
+	/* rollback pgdat allocation and others */
+	if (new_node)
+		rollback_node_hotadd(nid);
+	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)
+{
+	struct resource *res;
+	int ret;
+
+	res = register_memory_resource(start, size);
+	if (IS_ERR(res))
+		return PTR_ERR(res);
+
+	ret = add_memory_resource(nid, res, memhp_auto_online);
+	if (ret < 0)
+		release_memory_resource(res);
+	return ret;
+}
+
+int add_memory(int nid, u64 start, u64 size)
+{
+	int rc;
+
+	lock_device_hotplug();
+	rc = __add_memory(nid, start, size);
+	unlock_device_hotplug();
+
+	return rc;
+}
+EXPORT_SYMBOL_GPL(add_memory);
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+/*
+ * A free page on the buddy free lists (not the per-cpu lists) has PageBuddy
+ * set and the size of the free page is given by page_order(). Using this,
+ * the function determines if the pageblock contains only free pages.
+ * Due to buddy contraints, a free page at least the size of a pageblock will
+ * be located at the start of the pageblock
+ */
+static inline int pageblock_free(struct page *page)
+{
+	return PageBuddy(page) && page_order(page) >= pageblock_order;
+}
+
+/* Return the pfn of the start of the next active pageblock after a given pfn */
+static unsigned long next_active_pageblock(unsigned long pfn)
+{
+	struct page *page = pfn_to_page(pfn);
+
+	/* Ensure the starting page is pageblock-aligned */
+	BUG_ON(pfn & (pageblock_nr_pages - 1));
+
+	/* If the entire pageblock is free, move to the end of free page */
+	if (pageblock_free(page)) {
+		int order;
+		/* be careful. we don't have locks, page_order can be changed.*/
+		order = page_order(page);
+		if ((order < MAX_ORDER) && (order >= pageblock_order))
+			return pfn + (1 << order);
+	}
+
+	return pfn + pageblock_nr_pages;
+}
+
+static bool is_pageblock_removable_nolock(unsigned long pfn)
+{
+	struct page *page = pfn_to_page(pfn);
+	struct zone *zone;
+
+	/*
+	 * We have to be careful here because we are iterating over memory
+	 * sections which are not zone aware so we might end up outside of
+	 * the zone but still within the section.
+	 * We have to take care about the node as well. If the node is offline
+	 * its NODE_DATA will be NULL - see page_zone.
+	 */
+	if (!node_online(page_to_nid(page)))
+		return false;
+
+	zone = page_zone(page);
+	pfn = page_to_pfn(page);
+	if (!zone_spans_pfn(zone, pfn))
+		return false;
+
+	return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, true);
+}
+
+/* Checks if this range of memory is likely to be hot-removable. */
+bool is_mem_section_removable(unsigned long start_pfn, unsigned long nr_pages)
+{
+	unsigned long end_pfn, pfn;
+
+	end_pfn = min(start_pfn + nr_pages,
+			zone_end_pfn(page_zone(pfn_to_page(start_pfn))));
+
+	/* Check the starting page of each pageblock within the range */
+	for (pfn = start_pfn; pfn < end_pfn; pfn = next_active_pageblock(pfn)) {
+		if (!is_pageblock_removable_nolock(pfn))
+			return false;
+		cond_resched();
+	}
+
+	/* All pageblocks in the memory block are likely to be hot-removable */
+	return true;
+}
+
+/*
+ * Confirm all pages in a range [start, end) belong to the same zone.
+ * When true, return its valid [start, end).
+ */
+int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn,
+			 unsigned long *valid_start, unsigned long *valid_end)
+{
+	unsigned long pfn, sec_end_pfn;
+	unsigned long start, end;
+	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 0;
+			page = pfn_to_page(pfn + i);
+			if (zone && page_zone(page) != zone)
+				return 0;
+			if (!zone)
+				start = pfn + i;
+			zone = page_zone(page);
+			end = pfn + MAX_ORDER_NR_PAGES;
+		}
+	}
+
+	if (zone) {
+		*valid_start = start;
+		*valid_end = min(end, end_pfn);
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+/*
+ * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
+ * non-lru movable pages and hugepages). We scan pfn because it's much
+ * easier than scanning over linked list. This function returns the pfn
+ * of the first found movable page if it's found, otherwise 0.
+ */
+static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
+{
+	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))
+			return pfn;
+		if (__PageMovable(page))
+			return pfn;
+
+		if (!PageHuge(page))
+			continue;
+		head = compound_head(page);
+		if (hugepage_migration_supported(page_hstate(head)) &&
+		    page_huge_active(head))
+			return pfn;
+		skip = (1 << compound_order(head)) - (page - head);
+		pfn += skip - 1;
+	}
+	return 0;
+}
+
+static struct page *new_node_page(struct page *page, unsigned long private)
+{
+	int nid = page_to_nid(page);
+	nodemask_t nmask = node_states[N_MEMORY];
+
+	/*
+	 * 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(nid, nmask);
+	if (nodes_empty(nmask))
+		node_set(nid, nmask);
+
+	return new_page_nodemask(page, nid, &nmask);
+}
+
+#define NR_OFFLINE_AT_ONCE_PAGES	(256)
+static int
+do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
+{
+	unsigned long pfn;
+	struct page *page;
+	int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
+	int not_managed = 0;
+	int ret = 0;
+	LIST_HEAD(source);
+
+	for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
+		if (!pfn_valid(pfn))
+			continue;
+		page = pfn_to_page(pfn);
+
+		if (PageHuge(page)) {
+			struct page *head = compound_head(page);
+			pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1;
+			if (compound_order(head) > PFN_SECTION_SHIFT) {
+				ret = -EBUSY;
+				break;
+			}
+			if (isolate_huge_page(page, &source))
+				move_pages -= 1 << compound_order(head);
+			continue;
+		} else if (PageTransHuge(page))
+			pfn = page_to_pfn(compound_head(page))
+				+ hpage_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 | TTU_IGNORE_ACCESS);
+			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 */
+			put_page(page);
+			list_add_tail(&page->lru, &source);
+			move_pages--;
+			if (!__PageMovable(page))
+				inc_node_page_state(page, NR_ISOLATED_ANON +
+						    page_is_file_cache(page));
+
+		} else {
+#ifdef CONFIG_DEBUG_VM
+			pr_alert("failed to isolate pfn %lx\n", pfn);
+			dump_page(page, "isolation failed");
+#endif
+			put_page(page);
+			/* Because we don't have big zone->lock. we should
+			   check this again here. */
+			if (page_count(page)) {
+				not_managed++;
+				ret = -EBUSY;
+				break;
+			}
+		}
+	}
+	if (!list_empty(&source)) {
+		if (not_managed) {
+			putback_movable_pages(&source);
+			goto out;
+		}
+
+		/* Allocate a new page from the nearest neighbor node */
+		ret = migrate_pages(&source, new_node_page, NULL, 0,
+					MIGRATE_SYNC, MR_MEMORY_HOTPLUG);
+		if (ret)
+			putback_movable_pages(&source);
+	}
+out:
+	return ret;
+}
+
+/*
+ * remove from free_area[] and mark all as Reserved.
+ */
+static int
+offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
+			void *data)
+{
+	__offline_isolated_pages(start, start + nr_pages);
+	return 0;
+}
+
+static void
+offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
+{
+	walk_system_ram_range(start_pfn, end_pfn - start_pfn, NULL,
+				offline_isolated_pages_cb);
+}
+
+/*
+ * Check all pages in range, recoreded as memory resource, are isolated.
+ */
+static int
+check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
+			void *data)
+{
+	int ret;
+	long offlined = *(long *)data;
+	ret = test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
+	offlined = nr_pages;
+	if (!ret)
+		*(long *)data += offlined;
+	return ret;
+}
+
+static long
+check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
+{
+	long offlined = 0;
+	int ret;
+
+	ret = walk_system_ram_range(start_pfn, end_pfn - start_pfn, &offlined,
+			check_pages_isolated_cb);
+	if (ret < 0)
+		offlined = (long)ret;
+	return offlined;
+}
+
+static int __init cmdline_parse_movable_node(char *p)
+{
+#ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
+	movable_node_enabled = true;
+#else
+	pr_warn("movable_node parameter depends on CONFIG_HAVE_MEMBLOCK_NODE_MAP to work properly\n");
+#endif
+	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, zone_last = ZONE_NORMAL;
+
+	/*
+	 * If we have HIGHMEM or movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_NORMAL,
+	 * set zone_last to ZONE_NORMAL.
+	 *
+	 * If we don't have HIGHMEM nor movable node,
+	 * node_states[N_NORMAL_MEMORY] contains nodes which have zones of
+	 * 0...ZONE_MOVABLE, set zone_last to ZONE_MOVABLE.
+	 */
+	if (N_MEMORY == N_NORMAL_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	/*
+	 * check whether node_states[N_NORMAL_MEMORY] will be changed.
+	 * If the memory to be offline is in a zone of 0...zone_last,
+	 * and it is the last present memory, 0...zone_last will
+	 * become empty after offline , thus we can determind we will
+	 * need to clear the node from node_states[N_NORMAL_MEMORY].
+	 */
+	for (zt = 0; zt <= zone_last; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
+		arg->status_change_nid_normal = zone_to_nid(zone);
+	else
+		arg->status_change_nid_normal = -1;
+
+#ifdef CONFIG_HIGHMEM
+	/*
+	 * If we have movable node, node_states[N_HIGH_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_HIGHMEM,
+	 * set zone_last to ZONE_HIGHMEM.
+	 *
+	 * If we don't have movable node, node_states[N_NORMAL_MEMORY]
+	 * contains nodes which have zones of 0...ZONE_MOVABLE,
+	 * set zone_last to ZONE_MOVABLE.
+	 */
+	zone_last = ZONE_HIGHMEM;
+	if (N_MEMORY == N_HIGH_MEMORY)
+		zone_last = ZONE_MOVABLE;
+
+	for (; zt <= zone_last; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (zone_idx(zone) <= zone_last && nr_pages >= present_pages)
+		arg->status_change_nid_high = zone_to_nid(zone);
+	else
+		arg->status_change_nid_high = -1;
+#else
+	arg->status_change_nid_high = arg->status_change_nid_normal;
+#endif
+
+	/*
+	 * node_states[N_HIGH_MEMORY] contains nodes which have 0...ZONE_MOVABLE
+	 */
+	zone_last = ZONE_MOVABLE;
+
+	/*
+	 * check whether node_states[N_HIGH_MEMORY] will be changed
+	 * If we try to offline the last present @nr_pages from the node,
+	 * we can determind we will need to clear the node from
+	 * node_states[N_HIGH_MEMORY].
+	 */
+	for (; zt <= zone_last; zt++)
+		present_pages += pgdat->node_zones[zt].present_pages;
+	if (nr_pages >= present_pages)
+		arg->status_change_nid = zone_to_nid(zone);
+	else
+		arg->status_change_nid = -1;
+}
+
+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 ((N_MEMORY != N_NORMAL_MEMORY) &&
+	    (arg->status_change_nid_high >= 0))
+		node_clear_state(node, N_HIGH_MEMORY);
+
+	if ((N_MEMORY != N_HIGH_MEMORY) &&
+	    (arg->status_change_nid >= 0))
+		node_clear_state(node, N_MEMORY);
+}
+
+static int __ref __offline_pages(unsigned long start_pfn,
+		  unsigned long end_pfn)
+{
+	unsigned long pfn, nr_pages;
+	long offlined_pages;
+	int ret, node;
+	unsigned long flags;
+	unsigned long valid_start, valid_end;
+	struct zone *zone;
+	struct memory_notify arg;
+
+	/* at least, alignment against pageblock is necessary */
+	if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
+		return -EINVAL;
+	if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
+		return -EINVAL;
+
+	mem_hotplug_begin();
+
+	/* This makes hotplug much easier...and readable.
+	   we assume this for now. .*/
+	if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start,
+				  &valid_end)) {
+		mem_hotplug_done();
+		return -EINVAL;
+	}
+
+	zone = page_zone(pfn_to_page(valid_start));
+	node = zone_to_nid(zone);
+	nr_pages = end_pfn - start_pfn;
+
+	/* set above range as isolated */
+	ret = start_isolate_page_range(start_pfn, end_pfn,
+				       MIGRATE_MOVABLE, true);
+	if (ret) {
+		mem_hotplug_done();
+		return ret;
+	}
+
+	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)
+		goto failed_removal;
+
+	pfn = start_pfn;
+repeat:
+	/* start memory hot removal */
+	ret = -EINTR;
+	if (signal_pending(current))
+		goto failed_removal;
+
+	cond_resched();
+	lru_add_drain_all();
+	drain_all_pages(zone);
+
+	pfn = scan_movable_pages(start_pfn, end_pfn);
+	if (pfn) { /* We have movable pages */
+		ret = do_migrate_range(pfn, end_pfn);
+		goto repeat;
+	}
+
+	/*
+	 * 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)
+		goto failed_removal;
+	/* check again */
+	offlined_pages = check_pages_isolated(start_pfn, end_pfn);
+	if (offlined_pages < 0)
+		goto repeat;
+	pr_info("Offlined Pages %ld\n", offlined_pages);
+	/* Ok, all of our target is isolated.
+	   We cannot do rollback at this point. */
+	offline_isolated_pages(start_pfn, end_pfn);
+	/* reset pagetype flags and makes migrate type to be MOVABLE */
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	/* removal success */
+	adjust_managed_page_count(pfn_to_page(start_pfn), -offlined_pages);
+	zone->present_pages -= offlined_pages;
+
+	pgdat_resize_lock(zone->zone_pgdat, &flags);
+	zone->zone_pgdat->node_present_pages -= offlined_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);
+	}
+
+	vm_total_pages = nr_free_pagecache_pages();
+	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:
+	pr_debug("memory offlining [mem %#010llx-%#010llx] failed\n",
+		 (unsigned long long) start_pfn << PAGE_SHIFT,
+		 ((unsigned long long) end_pfn << PAGE_SHIFT) - 1);
+	memory_notify(MEM_CANCEL_OFFLINE, &arg);
+	/* pushback to free area */
+	undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
+	mem_hotplug_done();
+	return ret;
+}
+
+int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
+{
+	return __offline_pages(start_pfn, start_pfn + nr_pages);
+}
+#endif /* CONFIG_MEMORY_HOTREMOVE */
+
+/**
+ * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
+ * @start_pfn: start pfn of the memory range
+ * @end_pfn: end pfn of the memory range
+ * @arg: argument passed to func
+ * @func: callback for each memory section walked
+ *
+ * This function walks through all present mem sections in range
+ * [start_pfn, end_pfn) and call func on each mem section.
+ *
+ * Returns the return value of func.
+ */
+int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+		void *arg, int (*func)(struct memory_block *, void *))
+{
+	struct memory_block *mem = NULL;
+	struct mem_section *section;
+	unsigned long pfn, section_nr;
+	int ret;
+
+	for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+		section_nr = pfn_to_section_nr(pfn);
+		if (!present_section_nr(section_nr))
+			continue;
+
+		section = __nr_to_section(section_nr);
+		/* same memblock? */
+		if (mem)
+			if ((section_nr >= mem->start_section_nr) &&
+			    (section_nr <= mem->end_section_nr))
+				continue;
+
+		mem = find_memory_block_hinted(section, mem);
+		if (!mem)
+			continue;
+
+		ret = func(mem, arg);
+		if (ret) {
+			kobject_put(&mem->dev.kobj);
+			return ret;
+		}
+	}
+
+	if (mem)
+		kobject_put(&mem->dev.kobj);
+
+	return 0;
+}
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+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 = PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1))-1;
+		pr_warn("removing memory fails, because memory [%pa-%pa] is onlined\n",
+			&beginpa, &endpa);
+	}
+
+	return ret;
+}
+
+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 void unmap_cpu_on_node(pg_data_t *pgdat)
+{
+#ifdef CONFIG_ACPI_NUMA
+	int cpu;
+
+	for_each_possible_cpu(cpu)
+		if (cpu_to_node(cpu) == pgdat->node_id)
+			numa_clear_node(cpu);
+#endif
+}
+
+static int check_and_unmap_cpu_on_node(pg_data_t *pgdat)
+{
+	int ret;
+
+	ret = check_cpu_on_node(pgdat);
+	if (ret)
+		return ret;
+
+	/*
+	 * the node will be offlined when we come here, so we can clear
+	 * the cpu_to_node() now.
+	 */
+
+	unmap_cpu_on_node(pgdat);
+	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_and_unmap_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 void __release_memory_resource(resource_size_t start,
+				      resource_size_t size)
+{
+	int ret;
+
+	/*
+	 * When removing memory in the same granularity as it was added,
+	 * this function never fails. It might only fail if resources
+	 * have to be adjusted or split. We'll ignore the error, as
+	 * removing of memory cannot fail.
+	 */
+	ret = release_mem_region_adjustable(&iomem_resource, start, size);
+	if (ret) {
+		resource_size_t endres = start + size - 1;
+
+		pr_warn("Unable to release resource <%pa-%pa> (%d)\n",
+			&start, &endres, ret);
+	}
+}
+
+/**
+ * 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 __ref __remove_memory(int nid, u64 start, u64 size)
+{
+	int ret;
+
+	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 trigger a BUG()
+	 * if this is not the case.
+	 */
+	ret = walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1), NULL,
+				check_memblock_offlined_cb);
+	if (ret)
+		BUG();
+
+	/* remove memmap entry */
+	firmware_map_remove(start, start + size, "System RAM");
+	memblock_free(start, size);
+	memblock_remove(start, size);
+
+	/*
+	 * 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);
+	__release_memory_resource(start, size);
+
+	try_offline_node(nid);
+
+	mem_hotplug_done();
+}
+
+void remove_memory(int nid, u64 start, u64 size)
+{
+	lock_device_hotplug();
+	__remove_memory(nid, start, size);
+	unlock_device_hotplug();
+}
+EXPORT_SYMBOL_GPL(remove_memory);
+#endif /* CONFIG_MEMORY_HOTREMOVE */