mm/memory_hotplug.c

   1 /*
   2  *  linux/mm/memory_hotplug.c
   3  *
   4  *  Copyright (C)
   5  */
   6
   7 #include <linux/stddef.h>
   8 #include <linux/mm.h>
   9 #include <linux/swap.h>
  10 #include <linux/interrupt.h>
  11 #include <linux/pagemap.h>
  12 #include <linux/bootmem.h>
  13 #include <linux/compiler.h>
  14 #include <linux/module.h>
  15 #include <linux/pagevec.h>
  16 #include <linux/writeback.h>
  17 #include <linux/slab.h>
  18 #include <linux/sysctl.h>
  19 #include <linux/cpu.h>
  20 #include <linux/memory.h>
  21 #include <linux/memory_hotplug.h>
  22 #include <linux/highmem.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/ioport.h>
  25 #include <linux/cpuset.h>
  26 #include <linux/delay.h>
  27 #include <linux/migrate.h>
  28 #include <linux/page-isolation.h>
  29
  30 #include <asm/tlbflush.h>
  31
  32 /* add this memory to iomem resource */
  33 static struct resource *register_memory_resource(u64 start, u64 size)
  34 {
  35         struct resource *res;
  36         res = kzalloc(sizeof(struct resource), GFP_KERNEL);
  37         BUG_ON(!res);
  38
  39         res->name = "System RAM";
  40         res->start = start;
  41         res->end = start + size - 1;
  42         res->flags = IORESOURCE_MEM | IORESOURCE_BUSY;
  43         if (request_resource(&iomem_resource, res) < 0) {
  44                 printk("System RAM resource %llx - %llx cannot be added\n",
  45                 (unsigned long long)res->start, (unsigned long long)res->end);
  46                 kfree(res);
  47                 res = NULL;
  48         }
  49         return res;
  50 }
  51
  52 static void release_memory_resource(struct resource *res)
  53 {
  54         if (!res)
  55                 return;
  56         release_resource(res);
  57         kfree(res);
  58         return;
  59 }
  60
  61
  62 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
  63 static int __add_zone(struct zone *zone, unsigned long phys_start_pfn)
  64 {
  65         struct pglist_data *pgdat = zone->zone_pgdat;
  66         int nr_pages = PAGES_PER_SECTION;
  67         int nid = pgdat->node_id;
  68         int zone_type;
  69
  70         zone_type = zone - pgdat->node_zones;
  71         if (!zone->wait_table) {
  72                 int ret = 0;
  73                 ret = init_currently_empty_zone(zone, phys_start_pfn,
  74                                                 nr_pages, MEMMAP_HOTPLUG);
  75                 if (ret < 0)
  76                         return ret;
  77         }
  78         memmap_init_zone(nr_pages, nid, zone_type,
  79                          phys_start_pfn, MEMMAP_HOTPLUG);
  80         return 0;
  81 }
  82
  83 static int __add_section(struct zone *zone, unsigned long phys_start_pfn)
  84 {
  85         int nr_pages = PAGES_PER_SECTION;
  86         int ret;
  87
  88         if (pfn_valid(phys_start_pfn))
  89                 return -EEXIST;
  90
  91         ret = sparse_add_one_section(zone, phys_start_pfn, nr_pages);
  92
  93         if (ret < 0)
  94                 return ret;
  95
  96         ret = __add_zone(zone, phys_start_pfn);
  97
  98         if (ret < 0)
  99                 return ret;
 100
 101         return register_new_memory(__pfn_to_section(phys_start_pfn));
 102 }
 103
 104 /*
 105  * Reasonably generic function for adding memory.  It is
 106  * expected that archs that support memory hotplug will
 107  * call this function after deciding the zone to which to
 108  * add the new pages.
 109  */
 110 int __add_pages(struct zone *zone, unsigned long phys_start_pfn,
 111                  unsigned long nr_pages)
 112 {
 113         unsigned long i;
 114         int err = 0;
 115         int start_sec, end_sec;
 116         /* during initialize mem_map, align hot-added range to section */
 117         start_sec = pfn_to_section_nr(phys_start_pfn);
 118         end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
 119
 120         for (i = start_sec; i <= end_sec; i++) {
 121                 err = __add_section(zone, i << PFN_SECTION_SHIFT);
 122
 123                 /*
 124                  * EEXIST is finally dealt with by ioresource collision
 125                  * check. see add_memory() => register_memory_resource()
 126                  * Warning will be printed if there is collision.
 127                  */
 128                 if (err && (err != -EEXIST))
 129                         break;
 130                 err = 0;
 131         }
 132
 133         return err;
 134 }
 135 EXPORT_SYMBOL_GPL(__add_pages);
 136
 137 static void grow_zone_span(struct zone *zone,
 138                 unsigned long start_pfn, unsigned long end_pfn)
 139 {
 140         unsigned long old_zone_end_pfn;
 141
 142         zone_span_writelock(zone);
 143
 144         old_zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
 145         if (start_pfn < zone->zone_start_pfn)
 146                 zone->zone_start_pfn = start_pfn;
 147
 148         zone->spanned_pages = max(old_zone_end_pfn, end_pfn) -
 149                                 zone->zone_start_pfn;
 150
 151         zone_span_writeunlock(zone);
 152 }
 153
 154 static void grow_pgdat_span(struct pglist_data *pgdat,
 155                 unsigned long start_pfn, unsigned long end_pfn)
 156 {
 157         unsigned long old_pgdat_end_pfn =
 158                 pgdat->node_start_pfn + pgdat->node_spanned_pages;
 159
 160         if (start_pfn < pgdat->node_start_pfn)
 161                 pgdat->node_start_pfn = start_pfn;
 162
 163         pgdat->node_spanned_pages = max(old_pgdat_end_pfn, end_pfn) -
 164                                         pgdat->node_start_pfn;
 165 }
 166
 167 static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
 168                         void *arg)
 169 {
 170         unsigned long i;
 171         unsigned long onlined_pages = *(unsigned long *)arg;
 172         struct page *page;
 173         if (PageReserved(pfn_to_page(start_pfn)))
 174                 for (i = 0; i < nr_pages; i++) {
 175                         page = pfn_to_page(start_pfn + i);
 176                         online_page(page);
 177                         onlined_pages++;
 178                 }
 179         *(unsigned long *)arg = onlined_pages;
 180         return 0;
 181 }
 182
 183
 184 int online_pages(unsigned long pfn, unsigned long nr_pages)
 185 {
 186         unsigned long flags;
 187         unsigned long onlined_pages = 0;
 188         struct zone *zone;
 189         int need_zonelists_rebuild = 0;
 190         int nid;
 191         int ret;
 192         struct memory_notify arg;
 193
 194         arg.start_pfn = pfn;
 195         arg.nr_pages = nr_pages;
 196         arg.status_change_nid = -1;
 197
 198         nid = page_to_nid(pfn_to_page(pfn));
 199         if (node_present_pages(nid) == 0)
 200                 arg.status_change_nid = nid;
 201
 202         ret = memory_notify(MEM_GOING_ONLINE, &arg);
 203         ret = notifier_to_errno(ret);
 204         if (ret) {
 205                 memory_notify(MEM_CANCEL_ONLINE, &arg);
 206                 return ret;
 207         }
 208         /*
 209          * This doesn't need a lock to do pfn_to_page().
 210          * The section can't be removed here because of the
 211          * memory_block->state_sem.
 212          */
 213         zone = page_zone(pfn_to_page(pfn));
 214         pgdat_resize_lock(zone->zone_pgdat, &flags);
 215         grow_zone_span(zone, pfn, pfn + nr_pages);
 216         grow_pgdat_span(zone->zone_pgdat, pfn, pfn + nr_pages);
 217         pgdat_resize_unlock(zone->zone_pgdat, &flags);
 218
 219         /*
 220          * If this zone is not populated, then it is not in zonelist.
 221          * This means the page allocator ignores this zone.
 222          * So, zonelist must be updated after online.
 223          */
 224         if (!populated_zone(zone))
 225                 need_zonelists_rebuild = 1;
 226
 227         walk_memory_resource(pfn, nr_pages, &onlined_pages,
 228                 online_pages_range);
 229         zone->present_pages += onlined_pages;
 230         zone->zone_pgdat->node_present_pages += onlined_pages;
 231
 232         setup_per_zone_pages_min();
 233         if (onlined_pages) {
 234                 kswapd_run(zone_to_nid(zone));
 235                 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
 236         }
 237
 238         if (need_zonelists_rebuild)
 239                 build_all_zonelists();
 240         vm_total_pages = nr_free_pagecache_pages();
 241         writeback_set_ratelimit();
 242
 243         if (onlined_pages)
 244                 memory_notify(MEM_ONLINE, &arg);
 245
 246         return 0;
 247 }
 248 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 249
 250 static pg_data_t *hotadd_new_pgdat(int nid, u64 start)
 251 {
 252         struct pglist_data *pgdat;
 253         unsigned long zones_size[MAX_NR_ZONES] = {0};
 254         unsigned long zholes_size[MAX_NR_ZONES] = {0};
 255         unsigned long start_pfn = start >> PAGE_SHIFT;
 256
 257         pgdat = arch_alloc_nodedata(nid);
 258         if (!pgdat)
 259                 return NULL;
 260
 261         arch_refresh_nodedata(nid, pgdat);
 262
 263         /* we can use NODE_DATA(nid) from here */
 264
 265         /* init node's zones as empty zones, we don't have any present pages.*/
 266         free_area_init_node(nid, pgdat, zones_size, start_pfn, zholes_size);
 267
 268         return pgdat;
 269 }
 270
 271 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
 272 {
 273         arch_refresh_nodedata(nid, NULL);
 274         arch_free_nodedata(pgdat);
 275         return;
 276 }
 277
 278
 279 int add_memory(int nid, u64 start, u64 size)
 280 {
 281         pg_data_t *pgdat = NULL;
 282         int new_pgdat = 0;
 283         struct resource *res;
 284         int ret;
 285
 286         res = register_memory_resource(start, size);
 287         if (!res)
 288                 return -EEXIST;
 289
 290         if (!node_online(nid)) {
 291                 pgdat = hotadd_new_pgdat(nid, start);
 292                 if (!pgdat)
 293                         return -ENOMEM;
 294                 new_pgdat = 1;
 295         }
 296
 297         /* call arch's memory hotadd */
 298         ret = arch_add_memory(nid, start, size);
 299
 300         if (ret < 0)
 301                 goto error;
 302
 303         /* we online node here. we can't roll back from here. */
 304         node_set_online(nid);
 305
 306         cpuset_track_online_nodes();
 307
 308         if (new_pgdat) {
 309                 ret = register_one_node(nid);
 310                 /*
 311                  * If sysfs file of new node can't create, cpu on the node
 312                  * can't be hot-added. There is no rollback way now.
 313                  * So, check by BUG_ON() to catch it reluctantly..
 314                  */
 315                 BUG_ON(ret);
 316         }
 317
 318         return ret;
 319 error:
 320         /* rollback pgdat allocation and others */
 321         if (new_pgdat)
 322                 rollback_node_hotadd(nid, pgdat);
 323         if (res)
 324                 release_memory_resource(res);
 325
 326         return ret;
 327 }
 328 EXPORT_SYMBOL_GPL(add_memory);
 329
 330 #ifdef CONFIG_MEMORY_HOTREMOVE
 331 /*
 332  * Confirm all pages in a range [start, end) is belongs to the same zone.
 333  */
 334 static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
 335 {
 336         unsigned long pfn;
 337         struct zone *zone = NULL;
 338         struct page *page;
 339         int i;
 340         for (pfn = start_pfn;
 341              pfn < end_pfn;
 342              pfn += MAX_ORDER_NR_PAGES) {
 343                 i = 0;
 344                 /* This is just a CONFIG_HOLES_IN_ZONE check.*/
 345                 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
 346                         i++;
 347                 if (i == MAX_ORDER_NR_PAGES)
 348                         continue;
 349                 page = pfn_to_page(pfn + i);
 350                 if (zone && page_zone(page) != zone)
 351                         return 0;
 352                 zone = page_zone(page);
 353         }
 354         return 1;
 355 }
 356
 357 /*
 358  * Scanning pfn is much easier than scanning lru list.
 359  * Scan pfn from start to end and Find LRU page.
 360  */
 361 int scan_lru_pages(unsigned long start, unsigned long end)
 362 {
 363         unsigned long pfn;
 364         struct page *page;
 365         for (pfn = start; pfn < end; pfn++) {
 366                 if (pfn_valid(pfn)) {
 367                         page = pfn_to_page(pfn);
 368                         if (PageLRU(page))
 369                                 return pfn;
 370                 }
 371         }
 372         return 0;
 373 }
 374
 375 static struct page *
 376 hotremove_migrate_alloc(struct page *page,
 377                         unsigned long private,
 378                         int **x)
 379 {
 380         /* This should be improoooooved!! */
 381         return alloc_page(GFP_HIGHUSER_PAGECACHE);
 382 }
 383
 384
 385 #define NR_OFFLINE_AT_ONCE_PAGES        (256)
 386 static int
 387 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 388 {
 389         unsigned long pfn;
 390         struct page *page;
 391         int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
 392         int not_managed = 0;
 393         int ret = 0;
 394         LIST_HEAD(source);
 395
 396         for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
 397                 if (!pfn_valid(pfn))
 398                         continue;
 399                 page = pfn_to_page(pfn);
 400                 if (!page_count(page))
 401                         continue;
 402                 /*
 403                  * We can skip free pages. And we can only deal with pages on
 404                  * LRU.
 405                  */
 406                 ret = isolate_lru_page(page, &source);
 407                 if (!ret) { /* Success */
 408                         move_pages--;
 409                 } else {
 410                         /* Becasue we don't have big zone->lock. we should
 411                            check this again here. */
 412                         if (page_count(page))
 413                                 not_managed++;
 414 #ifdef CONFIG_DEBUG_VM
 415                         printk(KERN_INFO "removing from LRU failed"
 416                                          " %lx/%d/%lx\n",
 417                                 pfn, page_count(page), page->flags);
 418 #endif
 419                 }
 420         }
 421         ret = -EBUSY;
 422         if (not_managed) {
 423                 if (!list_empty(&source))
 424                         putback_lru_pages(&source);
 425                 goto out;
 426         }
 427         ret = 0;
 428         if (list_empty(&source))
 429                 goto out;
 430         /* this function returns # of failed pages */
 431         ret = migrate_pages(&source, hotremove_migrate_alloc, 0);
 432
 433 out:
 434         return ret;
 435 }
 436
 437 /*
 438  * remove from free_area[] and mark all as Reserved.
 439  */
 440 static int
 441 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
 442                         void *data)
 443 {
 444         __offline_isolated_pages(start, start + nr_pages);
 445         return 0;
 446 }
 447
 448 static void
 449 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 450 {
 451         walk_memory_resource(start_pfn, end_pfn - start_pfn, NULL,
 452                                 offline_isolated_pages_cb);
 453 }
 454
 455 /*
 456  * Check all pages in range, recoreded as memory resource, are isolated.
 457  */
 458 static int
 459 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
 460                         void *data)
 461 {
 462         int ret;
 463         long offlined = *(long *)data;
 464         ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
 465         offlined = nr_pages;
 466         if (!ret)
 467                 *(long *)data += offlined;
 468         return ret;
 469 }
 470
 471 static long
 472 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 473 {
 474         long offlined = 0;
 475         int ret;
 476
 477         ret = walk_memory_resource(start_pfn, end_pfn - start_pfn, &offlined,
 478                         check_pages_isolated_cb);
 479         if (ret < 0)
 480                 offlined = (long)ret;
 481         return offlined;
 482 }
 483
 484 int offline_pages(unsigned long start_pfn,
 485                   unsigned long end_pfn, unsigned long timeout)
 486 {
 487         unsigned long pfn, nr_pages, expire;
 488         long offlined_pages;
 489         int ret, drain, retry_max, node;
 490         struct zone *zone;
 491         struct memory_notify arg;
 492
 493         BUG_ON(start_pfn >= end_pfn);
 494         /* at least, alignment against pageblock is necessary */
 495         if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
 496                 return -EINVAL;
 497         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
 498                 return -EINVAL;
 499         /* This makes hotplug much easier...and readable.
 500            we assume this for now. .*/
 501         if (!test_pages_in_a_zone(start_pfn, end_pfn))
 502                 return -EINVAL;
 503
 504         zone = page_zone(pfn_to_page(start_pfn));
 505         node = zone_to_nid(zone);
 506         nr_pages = end_pfn - start_pfn;
 507
 508         /* set above range as isolated */
 509         ret = start_isolate_page_range(start_pfn, end_pfn);
 510         if (ret)
 511                 return ret;
 512
 513         arg.start_pfn = start_pfn;
 514         arg.nr_pages = nr_pages;
 515         arg.status_change_nid = -1;
 516         if (nr_pages >= node_present_pages(node))
 517                 arg.status_change_nid = node;
 518
 519         ret = memory_notify(MEM_GOING_OFFLINE, &arg);
 520         ret = notifier_to_errno(ret);
 521         if (ret)
 522                 goto failed_removal;
 523
 524         pfn = start_pfn;
 525         expire = jiffies + timeout;
 526         drain = 0;
 527         retry_max = 5;
 528 repeat:
 529         /* start memory hot removal */
 530         ret = -EAGAIN;
 531         if (time_after(jiffies, expire))
 532                 goto failed_removal;
 533         ret = -EINTR;
 534         if (signal_pending(current))
 535                 goto failed_removal;
 536         ret = 0;
 537         if (drain) {
 538                 lru_add_drain_all();
 539                 flush_scheduled_work();
 540                 cond_resched();
 541                 drain_all_pages();
 542         }
 543
 544         pfn = scan_lru_pages(start_pfn, end_pfn);
 545         if (pfn) { /* We have page on LRU */
 546                 ret = do_migrate_range(pfn, end_pfn);
 547                 if (!ret) {
 548                         drain = 1;
 549                         goto repeat;
 550                 } else {
 551                         if (ret < 0)
 552                                 if (--retry_max == 0)
 553                                         goto failed_removal;
 554                         yield();
 555                         drain = 1;
 556                         goto repeat;
 557                 }
 558         }
 559         /* drain all zone's lru pagevec, this is asyncronous... */
 560         lru_add_drain_all();
 561         flush_scheduled_work();
 562         yield();
 563         /* drain pcp pages , this is synchrouns. */
 564         drain_all_pages();
 565         /* check again */
 566         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 567         if (offlined_pages < 0) {
 568                 ret = -EBUSY;
 569                 goto failed_removal;
 570         }
 571         printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
 572         /* Ok, all of our target is islaoted.
 573            We cannot do rollback at this point. */
 574         offline_isolated_pages(start_pfn, end_pfn);
 575         /* reset pagetype flags and makes migrate type to be MOVABLE */
 576         undo_isolate_page_range(start_pfn, end_pfn);
 577         /* removal success */
 578         zone->present_pages -= offlined_pages;
 579         zone->zone_pgdat->node_present_pages -= offlined_pages;
 580         totalram_pages -= offlined_pages;
 581         num_physpages -= offlined_pages;
 582
 583         vm_total_pages = nr_free_pagecache_pages();
 584         writeback_set_ratelimit();
 585
 586         memory_notify(MEM_OFFLINE, &arg);
 587         return 0;
 588
 589 failed_removal:
 590         printk(KERN_INFO "memory offlining %lx to %lx failed\n",
 591                 start_pfn, end_pfn);
 592         memory_notify(MEM_CANCEL_OFFLINE, &arg);
 593         /* pushback to free area */
 594         undo_isolate_page_range(start_pfn, end_pfn);
 595
 596         return ret;
 597 }
 598 #else
 599 int remove_memory(u64 start, u64 size)
 600 {
 601         return -EINVAL;
 602 }
 603 EXPORT_SYMBOL_GPL(remove_memory);
 604 #endif /* CONFIG_MEMORY_HOTREMOVE */