/* * linux/mm/memory_hotplug.c * * Copyright (C) */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #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(NODE_DATA(nid), phys_start_pfn, altmap); if (ret < 0) return ret; if (!want_memblock) return 0; return hotplug_memory_register(nid, __pfn_to_section(phys_start_pfn)); } /* * 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; } #ifdef CONFIG_MEMORY_HOTREMOVE /* 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) { struct mem_section *ms; for (; start_pfn < end_pfn; start_pfn += PAGES_PER_SECTION) { ms = __pfn_to_section(start_pfn); if (unlikely(!valid_section(ms))) 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) { struct mem_section *ms; unsigned long pfn; /* pfn is the end pfn of a memory section. */ pfn = end_pfn - 1; for (; pfn >= start_pfn; pfn -= PAGES_PER_SECTION) { ms = __pfn_to_section(pfn); if (unlikely(!valid_section(ms))) 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; struct mem_section *ms; 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) { ms = __pfn_to_section(pfn); if (unlikely(!valid_section(ms))) 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 shrink_pgdat_span(struct pglist_data *pgdat, unsigned long start_pfn, unsigned long end_pfn) { unsigned long pgdat_start_pfn = pgdat->node_start_pfn; unsigned long p = pgdat_end_pfn(pgdat); /* pgdat_end_pfn namespace clash */ unsigned long pgdat_end_pfn = p; unsigned long pfn; struct mem_section *ms; int nid = pgdat->node_id; if (pgdat_start_pfn == start_pfn) { /* * If the section is smallest section in the pgdat, it need * shrink pgdat->node_start_pfn and pgdat->node_spanned_pages. * In this case, we find second smallest valid mem_section * for shrinking zone. */ pfn = find_smallest_section_pfn(nid, NULL, end_pfn, pgdat_end_pfn); if (pfn) { pgdat->node_start_pfn = pfn; pgdat->node_spanned_pages = pgdat_end_pfn - pfn; } } else if (pgdat_end_pfn == end_pfn) { /* * If the section is biggest section in the pgdat, it need * shrink pgdat->node_spanned_pages. * In this case, we find second biggest valid mem_section for * shrinking zone. */ pfn = find_biggest_section_pfn(nid, NULL, pgdat_start_pfn, start_pfn); if (pfn) pgdat->node_spanned_pages = pfn - pgdat_start_pfn + 1; } /* * If the section is not biggest or smallest mem_section in the pgdat, * it only creates a hole in the pgdat. So in this case, we need not * change the pgdat. * But perhaps, the pgdat has only hole data. Thus it check the pgdat * has only hole or not. */ pfn = pgdat_start_pfn; for (; pfn < pgdat_end_pfn; pfn += PAGES_PER_SECTION) { ms = __pfn_to_section(pfn); if (unlikely(!valid_section(ms))) continue; if (pfn_to_nid(pfn) != nid) 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 */ return; } /* The pgdat has no valid section */ pgdat->node_start_pfn = 0; pgdat->node_spanned_pages = 0; } static void __remove_zone(struct zone *zone, unsigned long start_pfn) { struct pglist_data *pgdat = zone->zone_pgdat; int nr_pages = PAGES_PER_SECTION; unsigned long flags; pgdat_resize_lock(zone->zone_pgdat, &flags); shrink_zone_span(zone, start_pfn, start_pfn + nr_pages); shrink_pgdat_span(pgdat, start_pfn, start_pfn + nr_pages); pgdat_resize_unlock(zone->zone_pgdat, &flags); } static int __remove_section(struct zone *zone, struct mem_section *ms, unsigned long map_offset, struct vmem_altmap *altmap) { unsigned long start_pfn; int scn_nr; int ret = -EINVAL; if (!valid_section(ms)) return ret; ret = unregister_memory_section(ms); if (ret) return ret; scn_nr = __section_nr(ms); start_pfn = section_nr_to_pfn((unsigned long)scn_nr); __remove_zone(zone, start_pfn); sparse_remove_one_section(zone, ms, map_offset, altmap); return 0; } /** * __remove_pages() - remove sections of pages from a zone * @zone: zone from which pages need to be removed * @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(). */ int __remove_pages(struct zone *zone, 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, ret = 0; /* In the ZONE_DEVICE case device driver owns the memory region */ if (is_dev_zone(zone)) { if (altmap) map_offset = vmem_altmap_offset(altmap); } else { resource_size_t start, size; start = phys_start_pfn << PAGE_SHIFT; size = nr_pages * PAGE_SIZE; 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); } } clear_zone_contiguous(zone); /* * 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(); ret = __remove_section(zone, __pfn_to_section(pfn), map_offset, altmap); map_offset = 0; if (ret) break; } set_zone_contiguous(zone); return ret; } #endif /* CONFIG_MEMORY_HOTREMOVE */ 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); arg->status_change_nid = -1; arg->status_change_nid_normal = -1; arg->status_change_nid_high = -1; if (!node_state(nid, N_MEMORY)) arg->status_change_nid = nid; if (zone_idx(zone) <= ZONE_NORMAL && !node_state(nid, N_NORMAL_MEMORY)) arg->status_change_nid_normal = nid; #ifdef CONFIG_HIGHMEM if (zone_idx(zone) <= N_HIGH_MEMORY && !node_state(nid, N_HIGH_MEMORY)) arg->status_change_nid_high = nid; #endif } static void node_states_set_node(int node, struct memory_notify *arg) { if (arg->status_change_nid_normal >= 0) node_set_state(node, N_NORMAL_MEMORY); if (arg->status_change_nid_high >= 0) node_set_state(node, N_HIGH_MEMORY); if (arg->status_change_nid >= 0) node_set_state(node, N_MEMORY); } static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn, unsigned long nr_pages) { unsigned long old_end_pfn = zone_end_pfn(zone); if (zone_is_empty(zone) || start_pfn < zone->zone_start_pfn) zone->zone_start_pfn = start_pfn; zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn; } static void __meminit resize_pgdat_range(struct pglist_data *pgdat, unsigned long start_pfn, unsigned long nr_pages) { unsigned long old_end_pfn = pgdat_end_pfn(pgdat); if (!pgdat->node_spanned_pages || start_pfn < pgdat->node_start_pfn) pgdat->node_start_pfn = start_pfn; pgdat->node_spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - pgdat->node_start_pfn; } 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, MEMMAP_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 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; /* 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); 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; 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)); 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 start of the next active pageblock after a given page */ static struct page *next_active_pageblock(struct page *page) { /* Ensure the starting page is pageblock-aligned */ BUG_ON(page_to_pfn(page) & (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 page + (1 << order); } return page + pageblock_nr_pages; } static bool is_pageblock_removable_nolock(struct page *page) { struct zone *zone; unsigned long pfn; /* * 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) { struct page *page = pfn_to_page(start_pfn); struct page *end_page = page + nr_pages; /* Check the starting page of each pageblock within the range */ for (; page < end_page; page = next_active_pageblock(page)) { if (!is_pageblock_removable_nolock(page)) 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; 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; struct page *page; for (pfn = start; pfn < end; pfn++) { if (pfn_valid(pfn)) { page = pfn_to_page(pfn); if (PageLRU(page)) return pfn; if (__PageMovable(page)) return pfn; if (PageHuge(page)) { if (hugepage_migration_supported(page_hstate(page)) && page_huge_active(page)) return pfn; else pfn = round_up(pfn + 1, 1 << compound_order(page)) - 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< 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; 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; arg->status_change_nid = -1; arg->status_change_nid_normal = -1; arg->status_change_nid_high = -1; /* * Check whether node_states[N_NORMAL_MEMORY] will be changed. * If the memory to be offline is within the range * [0..ZONE_NORMAL], and it is the last present memory there, * the zones in that range will become empty after the offlining, * thus we can determine that we need to clear the node from * node_states[N_NORMAL_MEMORY]. */ for (zt = 0; zt <= ZONE_NORMAL; zt++) present_pages += pgdat->node_zones[zt].present_pages; if (zone_idx(zone) <= ZONE_NORMAL && nr_pages >= present_pages) arg->status_change_nid_normal = zone_to_nid(zone); #ifdef CONFIG_HIGHMEM /* * node_states[N_HIGH_MEMORY] contains nodes which * have normal memory or high memory. * Here we add the present_pages belonging to ZONE_HIGHMEM. * If the zone is within the range of [0..ZONE_HIGHMEM), and * we determine that the zones in that range become empty, * we need to clear the node for N_HIGH_MEMORY. */ present_pages += pgdat->node_zones[ZONE_HIGHMEM].present_pages; if (zone_idx(zone) <= ZONE_HIGHMEM && nr_pages >= present_pages) arg->status_change_nid_high = zone_to_nid(zone); #endif /* * We have accounted the pages from [0..ZONE_NORMAL), and * in case of CONFIG_HIGHMEM the pages from ZONE_HIGHMEM * as well. * Here we count the possible pages from ZONE_MOVABLE. * If after having accounted all the pages, we see that the nr_pages * to be offlined is over or equal to the accounted pages, * we know that the node will become empty, and so, we can clear * it for N_MEMORY as well. */ present_pages += pgdat->node_zones[ZONE_MOVABLE].present_pages; if (nr_pages >= present_pages) arg->status_change_nid = zone_to_nid(zone); } static void node_states_clear_node(int node, struct memory_notify *arg) { if (arg->status_change_nid_normal >= 0) node_clear_state(node, N_NORMAL_MEMORY); if (arg->status_change_nid_high >= 0) node_clear_state(node, N_HIGH_MEMORY); if (arg->status_change_nid >= 0) node_clear_state(node, N_MEMORY); } static int __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); 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; } /** * 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); unsigned long start_pfn = pgdat->node_start_pfn; unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages; unsigned long pfn; for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { unsigned long section_nr = pfn_to_section_nr(pfn); if (!present_section_nr(section_nr)) continue; if (pfn_to_nid(pfn) != nid) continue; /* * some memory sections of this node are not removed, and we * can't offline node now. */ 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); /** * 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)); mem_hotplug_begin(); /* * 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); arch_remove_memory(start, size, NULL); 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 */