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;
  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 dealed 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
 191         /*
 192          * This doesn't need a lock to do pfn_to_page().
 193          * The section can't be removed here because of the
 194          * memory_block->state_sem.
 195          */
 196         zone = page_zone(pfn_to_page(pfn));
 197         pgdat_resize_lock(zone->zone_pgdat, &flags);
 198         grow_zone_span(zone, pfn, pfn + nr_pages);
 199         grow_pgdat_span(zone->zone_pgdat, pfn, pfn + nr_pages);
 200         pgdat_resize_unlock(zone->zone_pgdat, &flags);
 201
 202         /*
 203          * If this zone is not populated, then it is not in zonelist.
 204          * This means the page allocator ignores this zone.
 205          * So, zonelist must be updated after online.
 206          */
 207         if (!populated_zone(zone))
 208                 need_zonelists_rebuild = 1;
 209
 210         walk_memory_resource(pfn, nr_pages, &onlined_pages,
 211                 online_pages_range);
 212         zone->present_pages += onlined_pages;
 213         zone->zone_pgdat->node_present_pages += onlined_pages;
 214
 215         setup_per_zone_pages_min();
 216         if (onlined_pages) {
 217                 kswapd_run(zone_to_nid(zone));
 218                 node_set_state(zone_to_nid(zone), N_HIGH_MEMORY);
 219         }
 220
 221         if (need_zonelists_rebuild)
 222                 build_all_zonelists();
 223         vm_total_pages = nr_free_pagecache_pages();
 224         writeback_set_ratelimit();
 225         return 0;
 226 }
 227 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 228
 229 static pg_data_t *hotadd_new_pgdat(int nid, u64 start)
 230 {
 231         struct pglist_data *pgdat;
 232         unsigned long zones_size[MAX_NR_ZONES] = {0};
 233         unsigned long zholes_size[MAX_NR_ZONES] = {0};
 234         unsigned long start_pfn = start >> PAGE_SHIFT;
 235
 236         pgdat = arch_alloc_nodedata(nid);
 237         if (!pgdat)
 238                 return NULL;
 239
 240         arch_refresh_nodedata(nid, pgdat);
 241
 242         /* we can use NODE_DATA(nid) from here */
 243
 244         /* init node's zones as empty zones, we don't have any present pages.*/
 245         free_area_init_node(nid, pgdat, zones_size, start_pfn, zholes_size);
 246
 247         return pgdat;
 248 }
 249
 250 static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
 251 {
 252         arch_refresh_nodedata(nid, NULL);
 253         arch_free_nodedata(pgdat);
 254         return;
 255 }
 256
 257
 258 int add_memory(int nid, u64 start, u64 size)
 259 {
 260         pg_data_t *pgdat = NULL;
 261         int new_pgdat = 0;
 262         struct resource *res;
 263         int ret;
 264
 265         res = register_memory_resource(start, size);
 266         if (!res)
 267                 return -EEXIST;
 268
 269         if (!node_online(nid)) {
 270                 pgdat = hotadd_new_pgdat(nid, start);
 271                 if (!pgdat)
 272                         return -ENOMEM;
 273                 new_pgdat = 1;
 274         }
 275
 276         /* call arch's memory hotadd */
 277         ret = arch_add_memory(nid, start, size);
 278
 279         if (ret < 0)
 280                 goto error;
 281
 282         /* we online node here. we can't roll back from here. */
 283         node_set_online(nid);
 284
 285         cpuset_track_online_nodes();
 286
 287         if (new_pgdat) {
 288                 ret = register_one_node(nid);
 289                 /*
 290                  * If sysfs file of new node can't create, cpu on the node
 291                  * can't be hot-added. There is no rollback way now.
 292                  * So, check by BUG_ON() to catch it reluctantly..
 293                  */
 294                 BUG_ON(ret);
 295         }
 296
 297         return ret;
 298 error:
 299         /* rollback pgdat allocation and others */
 300         if (new_pgdat)
 301                 rollback_node_hotadd(nid, pgdat);
 302         if (res)
 303                 release_memory_resource(res);
 304
 305         return ret;
 306 }
 307 EXPORT_SYMBOL_GPL(add_memory);
 308
 309 #ifdef CONFIG_MEMORY_HOTREMOVE
 310 /*
 311  * Confirm all pages in a range [start, end) is belongs to the same zone.
 312  */
 313 static int test_pages_in_a_zone(unsigned long start_pfn, unsigned long end_pfn)
 314 {
 315         unsigned long pfn;
 316         struct zone *zone = NULL;
 317         struct page *page;
 318         int i;
 319         for (pfn = start_pfn;
 320              pfn < end_pfn;
 321              pfn += MAX_ORDER_NR_PAGES) {
 322                 i = 0;
 323                 /* This is just a CONFIG_HOLES_IN_ZONE check.*/
 324                 while ((i < MAX_ORDER_NR_PAGES) && !pfn_valid_within(pfn + i))
 325                         i++;
 326                 if (i == MAX_ORDER_NR_PAGES)
 327                         continue;
 328                 page = pfn_to_page(pfn + i);
 329                 if (zone && page_zone(page) != zone)
 330                         return 0;
 331                 zone = page_zone(page);
 332         }
 333         return 1;
 334 }
 335
 336 /*
 337  * Scanning pfn is much easier than scanning lru list.
 338  * Scan pfn from start to end and Find LRU page.
 339  */
 340 int scan_lru_pages(unsigned long start, unsigned long end)
 341 {
 342         unsigned long pfn;
 343         struct page *page;
 344         for (pfn = start; pfn < end; pfn++) {
 345                 if (pfn_valid(pfn)) {
 346                         page = pfn_to_page(pfn);
 347                         if (PageLRU(page))
 348                                 return pfn;
 349                 }
 350         }
 351         return 0;
 352 }
 353
 354 static struct page *
 355 hotremove_migrate_alloc(struct page *page,
 356                         unsigned long private,
 357                         int **x)
 358 {
 359         /* This should be improoooooved!! */
 360         return alloc_page(GFP_HIGHUSER_PAGECACHE);
 361 }
 362
 363
 364 #define NR_OFFLINE_AT_ONCE_PAGES        (256)
 365 static int
 366 do_migrate_range(unsigned long start_pfn, unsigned long end_pfn)
 367 {
 368         unsigned long pfn;
 369         struct page *page;
 370         int move_pages = NR_OFFLINE_AT_ONCE_PAGES;
 371         int not_managed = 0;
 372         int ret = 0;
 373         LIST_HEAD(source);
 374
 375         for (pfn = start_pfn; pfn < end_pfn && move_pages > 0; pfn++) {
 376                 if (!pfn_valid(pfn))
 377                         continue;
 378                 page = pfn_to_page(pfn);
 379                 if (!page_count(page))
 380                         continue;
 381                 /*
 382                  * We can skip free pages. And we can only deal with pages on
 383                  * LRU.
 384                  */
 385                 ret = isolate_lru_page(page, &source);
 386                 if (!ret) { /* Success */
 387                         move_pages--;
 388                 } else {
 389                         /* Becasue we don't have big zone->lock. we should
 390                            check this again here. */
 391                         if (page_count(page))
 392                                 not_managed++;
 393 #ifdef CONFIG_DEBUG_VM
 394                         printk(KERN_INFO "removing from LRU failed"
 395                                          " %lx/%d/%lx\n",
 396                                 pfn, page_count(page), page->flags);
 397 #endif
 398                 }
 399         }
 400         ret = -EBUSY;
 401         if (not_managed) {
 402                 if (!list_empty(&source))
 403                         putback_lru_pages(&source);
 404                 goto out;
 405         }
 406         ret = 0;
 407         if (list_empty(&source))
 408                 goto out;
 409         /* this function returns # of failed pages */
 410         ret = migrate_pages(&source, hotremove_migrate_alloc, 0);
 411
 412 out:
 413         return ret;
 414 }
 415
 416 /*
 417  * remove from free_area[] and mark all as Reserved.
 418  */
 419 static int
 420 offline_isolated_pages_cb(unsigned long start, unsigned long nr_pages,
 421                         void *data)
 422 {
 423         __offline_isolated_pages(start, start + nr_pages);
 424         return 0;
 425 }
 426
 427 static void
 428 offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 429 {
 430         walk_memory_resource(start_pfn, end_pfn - start_pfn, NULL,
 431                                 offline_isolated_pages_cb);
 432 }
 433
 434 /*
 435  * Check all pages in range, recoreded as memory resource, are isolated.
 436  */
 437 static int
 438 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
 439                         void *data)
 440 {
 441         int ret;
 442         long offlined = *(long *)data;
 443         ret = test_pages_isolated(start_pfn, start_pfn + nr_pages);
 444         offlined = nr_pages;
 445         if (!ret)
 446                 *(long *)data += offlined;
 447         return ret;
 448 }
 449
 450 static long
 451 check_pages_isolated(unsigned long start_pfn, unsigned long end_pfn)
 452 {
 453         long offlined = 0;
 454         int ret;
 455
 456         ret = walk_memory_resource(start_pfn, end_pfn - start_pfn, &offlined,
 457                         check_pages_isolated_cb);
 458         if (ret < 0)
 459                 offlined = (long)ret;
 460         return offlined;
 461 }
 462
 463 extern void drain_all_local_pages(void);
 464
 465 int offline_pages(unsigned long start_pfn,
 466                   unsigned long end_pfn, unsigned long timeout)
 467 {
 468         unsigned long pfn, nr_pages, expire;
 469         long offlined_pages;
 470         int ret, drain, retry_max;
 471         struct zone *zone;
 472
 473         BUG_ON(start_pfn >= end_pfn);
 474         /* at least, alignment against pageblock is necessary */
 475         if (!IS_ALIGNED(start_pfn, pageblock_nr_pages))
 476                 return -EINVAL;
 477         if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
 478                 return -EINVAL;
 479         /* This makes hotplug much easier...and readable.
 480            we assume this for now. .*/
 481         if (!test_pages_in_a_zone(start_pfn, end_pfn))
 482                 return -EINVAL;
 483         /* set above range as isolated */
 484         ret = start_isolate_page_range(start_pfn, end_pfn);
 485         if (ret)
 486                 return ret;
 487         nr_pages = end_pfn - start_pfn;
 488         pfn = start_pfn;
 489         expire = jiffies + timeout;
 490         drain = 0;
 491         retry_max = 5;
 492 repeat:
 493         /* start memory hot removal */
 494         ret = -EAGAIN;
 495         if (time_after(jiffies, expire))
 496                 goto failed_removal;
 497         ret = -EINTR;
 498         if (signal_pending(current))
 499                 goto failed_removal;
 500         ret = 0;
 501         if (drain) {
 502                 lru_add_drain_all();
 503                 flush_scheduled_work();
 504                 cond_resched();
 505                 drain_all_local_pages();
 506         }
 507
 508         pfn = scan_lru_pages(start_pfn, end_pfn);
 509         if (pfn) { /* We have page on LRU */
 510                 ret = do_migrate_range(pfn, end_pfn);
 511                 if (!ret) {
 512                         drain = 1;
 513                         goto repeat;
 514                 } else {
 515                         if (ret < 0)
 516                                 if (--retry_max == 0)
 517                                         goto failed_removal;
 518                         yield();
 519                         drain = 1;
 520                         goto repeat;
 521                 }
 522         }
 523         /* drain all zone's lru pagevec, this is asyncronous... */
 524         lru_add_drain_all();
 525         flush_scheduled_work();
 526         yield();
 527         /* drain pcp pages , this is synchrouns. */
 528         drain_all_local_pages();
 529         /* check again */
 530         offlined_pages = check_pages_isolated(start_pfn, end_pfn);
 531         if (offlined_pages < 0) {
 532                 ret = -EBUSY;
 533                 goto failed_removal;
 534         }
 535         printk(KERN_INFO "Offlined Pages %ld\n", offlined_pages);
 536         /* Ok, all of our target is islaoted.
 537            We cannot do rollback at this point. */
 538         offline_isolated_pages(start_pfn, end_pfn);
 539         /* reset pagetype flags */
 540         start_isolate_page_range(start_pfn, end_pfn);
 541         /* removal success */
 542         zone = page_zone(pfn_to_page(start_pfn));
 543         zone->present_pages -= offlined_pages;
 544         zone->zone_pgdat->node_present_pages -= offlined_pages;
 545         totalram_pages -= offlined_pages;
 546         num_physpages -= offlined_pages;
 547         vm_total_pages = nr_free_pagecache_pages();
 548         writeback_set_ratelimit();
 549         return 0;
 550
 551 failed_removal:
 552         printk(KERN_INFO "memory offlining %lx to %lx failed\n",
 553                 start_pfn, end_pfn);
 554         /* pushback to free area */
 555         undo_isolate_page_range(start_pfn, end_pfn);
 556         return ret;
 557 }
 558 #else
 559 int remove_memory(u64 start, u64 size)
 560 {
 561         return -EINVAL;
 562 }
 563 EXPORT_SYMBOL_GPL(remove_memory);
 564 #endif /* CONFIG_MEMORY_HOTREMOVE */