TOMOYO Linux Cross Reference
Linux/mm/memory_hotplug.c

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

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