drivers/base/memory.c

   1 /*
   2  * Memory subsystem support
   3  *
   4  * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
   5  *            Dave Hansen <haveblue@us.ibm.com>
   6  *
   7  * This file provides the necessary infrastructure to represent
   8  * a SPARSEMEM-memory-model system's physical memory in /sysfs.
   9  * All arch-independent code that assumes MEMORY_HOTPLUG requires
  10  * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/init.h>
  15 #include <linux/topology.h>
  16 #include <linux/capability.h>
  17 #include <linux/device.h>
  18 #include <linux/memory.h>
  19 #include <linux/memory_hotplug.h>
  20 #include <linux/mm.h>
  21 #include <linux/mutex.h>
  22 #include <linux/stat.h>
  23 #include <linux/slab.h>
  24
  25 #include <linux/atomic.h>
  26 #include <asm/uaccess.h>
  27
  28 static DEFINE_MUTEX(mem_sysfs_mutex);
  29
  30 #define MEMORY_CLASS_NAME       "memory"
  31
  32 #define to_memory_block(dev) container_of(dev, struct memory_block, dev)
  33
  34 static int sections_per_block;
  35
  36 static inline int base_memory_block_id(int section_nr)
  37 {
  38         return section_nr / sections_per_block;
  39 }
  40
  41 static int memory_subsys_online(struct device *dev);
  42 static int memory_subsys_offline(struct device *dev);
  43
  44 static struct bus_type memory_subsys = {
  45         .name = MEMORY_CLASS_NAME,
  46         .dev_name = MEMORY_CLASS_NAME,
  47         .online = memory_subsys_online,
  48         .offline = memory_subsys_offline,
  49 };
  50
  51 static BLOCKING_NOTIFIER_HEAD(memory_chain);
  52
  53 int register_memory_notifier(struct notifier_block *nb)
  54 {
  55         return blocking_notifier_chain_register(&memory_chain, nb);
  56 }
  57 EXPORT_SYMBOL(register_memory_notifier);
  58
  59 void unregister_memory_notifier(struct notifier_block *nb)
  60 {
  61         blocking_notifier_chain_unregister(&memory_chain, nb);
  62 }
  63 EXPORT_SYMBOL(unregister_memory_notifier);
  64
  65 static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
  66
  67 int register_memory_isolate_notifier(struct notifier_block *nb)
  68 {
  69         return atomic_notifier_chain_register(&memory_isolate_chain, nb);
  70 }
  71 EXPORT_SYMBOL(register_memory_isolate_notifier);
  72
  73 void unregister_memory_isolate_notifier(struct notifier_block *nb)
  74 {
  75         atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
  76 }
  77 EXPORT_SYMBOL(unregister_memory_isolate_notifier);
  78
  79 static void memory_block_release(struct device *dev)
  80 {
  81         struct memory_block *mem = to_memory_block(dev);
  82
  83         kfree(mem);
  84 }
  85
  86 unsigned long __weak memory_block_size_bytes(void)
  87 {
  88         return MIN_MEMORY_BLOCK_SIZE;
  89 }
  90
  91 static unsigned long get_memory_block_size(void)
  92 {
  93         unsigned long block_sz;
  94
  95         block_sz = memory_block_size_bytes();
  96
  97         /* Validate blk_sz is a power of 2 and not less than section size */
  98         if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
  99                 WARN_ON(1);
 100                 block_sz = MIN_MEMORY_BLOCK_SIZE;
 101         }
 102
 103         return block_sz;
 104 }
 105
 106 /*
 107  * use this as the physical section index that this memsection
 108  * uses.
 109  */
 110
 111 static ssize_t show_mem_start_phys_index(struct device *dev,
 112                         struct device_attribute *attr, char *buf)
 113 {
 114         struct memory_block *mem = to_memory_block(dev);
 115         unsigned long phys_index;
 116
 117         phys_index = mem->start_section_nr / sections_per_block;
 118         return sprintf(buf, "%08lx\n", phys_index);
 119 }
 120
 121 static ssize_t show_mem_end_phys_index(struct device *dev,
 122                         struct device_attribute *attr, char *buf)
 123 {
 124         struct memory_block *mem = to_memory_block(dev);
 125         unsigned long phys_index;
 126
 127         phys_index = mem->end_section_nr / sections_per_block;
 128         return sprintf(buf, "%08lx\n", phys_index);
 129 }
 130
 131 /*
 132  * Show whether the section of memory is likely to be hot-removable
 133  */
 134 static ssize_t show_mem_removable(struct device *dev,
 135                         struct device_attribute *attr, char *buf)
 136 {
 137         unsigned long i, pfn;
 138         int ret = 1;
 139         struct memory_block *mem = to_memory_block(dev);
 140
 141         for (i = 0; i < sections_per_block; i++) {
 142                 if (!present_section_nr(mem->start_section_nr + i))
 143                         continue;
 144                 pfn = section_nr_to_pfn(mem->start_section_nr + i);
 145                 ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
 146         }
 147
 148         return sprintf(buf, "%d\n", ret);
 149 }
 150
 151 /*
 152  * online, offline, going offline, etc.
 153  */
 154 static ssize_t show_mem_state(struct device *dev,
 155                         struct device_attribute *attr, char *buf)
 156 {
 157         struct memory_block *mem = to_memory_block(dev);
 158         ssize_t len = 0;
 159
 160         /*
 161          * We can probably put these states in a nice little array
 162          * so that they're not open-coded
 163          */
 164         switch (mem->state) {
 165                 case MEM_ONLINE:
 166                         len = sprintf(buf, "online\n");
 167                         break;
 168                 case MEM_OFFLINE:
 169                         len = sprintf(buf, "offline\n");
 170                         break;
 171                 case MEM_GOING_OFFLINE:
 172                         len = sprintf(buf, "going-offline\n");
 173                         break;
 174                 default:
 175                         len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
 176                                         mem->state);
 177                         WARN_ON(1);
 178                         break;
 179         }
 180
 181         return len;
 182 }
 183
 184 int memory_notify(unsigned long val, void *v)
 185 {
 186         return blocking_notifier_call_chain(&memory_chain, val, v);
 187 }
 188
 189 int memory_isolate_notify(unsigned long val, void *v)
 190 {
 191         return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
 192 }
 193
 194 /*
 195  * The probe routines leave the pages reserved, just as the bootmem code does.
 196  * Make sure they're still that way.
 197  */
 198 static bool pages_correctly_reserved(unsigned long start_pfn)
 199 {
 200         int i, j;
 201         struct page *page;
 202         unsigned long pfn = start_pfn;
 203
 204         /*
 205          * memmap between sections is not contiguous except with
 206          * SPARSEMEM_VMEMMAP. We lookup the page once per section
 207          * and assume memmap is contiguous within each section
 208          */
 209         for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
 210                 if (WARN_ON_ONCE(!pfn_valid(pfn)))
 211                         return false;
 212                 page = pfn_to_page(pfn);
 213
 214                 for (j = 0; j < PAGES_PER_SECTION; j++) {
 215                         if (PageReserved(page + j))
 216                                 continue;
 217
 218                         printk(KERN_WARNING "section number %ld page number %d "
 219                                 "not reserved, was it already online?\n",
 220                                 pfn_to_section_nr(pfn), j);
 221
 222                         return false;
 223                 }
 224         }
 225
 226         return true;
 227 }
 228
 229 /*
 230  * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
 231  * OK to have direct references to sparsemem variables in here.
 232  */
 233 static int
 234 memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
 235 {
 236         unsigned long start_pfn;
 237         unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
 238         struct page *first_page;
 239         int ret;
 240
 241         first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
 242         start_pfn = page_to_pfn(first_page);
 243
 244         switch (action) {
 245                 case MEM_ONLINE:
 246                         if (!pages_correctly_reserved(start_pfn))
 247                                 return -EBUSY;
 248
 249                         ret = online_pages(start_pfn, nr_pages, online_type);
 250                         break;
 251                 case MEM_OFFLINE:
 252                         ret = offline_pages(start_pfn, nr_pages);
 253                         break;
 254                 default:
 255                         WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
 256                              "%ld\n", __func__, phys_index, action, action);
 257                         ret = -EINVAL;
 258         }
 259
 260         return ret;
 261 }
 262
 263 static int memory_block_change_state(struct memory_block *mem,
 264                 unsigned long to_state, unsigned long from_state_req)
 265 {
 266         int ret = 0;
 267
 268         if (mem->state != from_state_req)
 269                 return -EINVAL;
 270
 271         if (to_state == MEM_OFFLINE)
 272                 mem->state = MEM_GOING_OFFLINE;
 273
 274         ret = memory_block_action(mem->start_section_nr, to_state,
 275                                 mem->online_type);
 276
 277         mem->state = ret ? from_state_req : to_state;
 278
 279         return ret;
 280 }
 281
 282 /* The device lock serializes operations on memory_subsys_[online|offline] */
 283 static int memory_subsys_online(struct device *dev)
 284 {
 285         struct memory_block *mem = to_memory_block(dev);
 286         int ret;
 287
 288         if (mem->state == MEM_ONLINE)
 289                 return 0;
 290
 291         /*
 292          * If we are called from store_mem_state(), online_type will be
 293          * set >= 0 Otherwise we were called from the device online
 294          * attribute and need to set the online_type.
 295          */
 296         if (mem->online_type < 0)
 297                 mem->online_type = ONLINE_KEEP;
 298
 299         ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
 300
 301         /* clear online_type */
 302         mem->online_type = -1;
 303
 304         return ret;
 305 }
 306
 307 static int memory_subsys_offline(struct device *dev)
 308 {
 309         struct memory_block *mem = to_memory_block(dev);
 310
 311         if (mem->state == MEM_OFFLINE)
 312                 return 0;
 313
 314         return memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
 315 }
 316
 317 static ssize_t
 318 store_mem_state(struct device *dev,
 319                 struct device_attribute *attr, const char *buf, size_t count)
 320 {
 321         struct memory_block *mem = to_memory_block(dev);
 322         int ret, online_type;
 323
 324         ret = lock_device_hotplug_sysfs();
 325         if (ret)
 326                 return ret;
 327
 328         if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))
 329                 online_type = ONLINE_KERNEL;
 330         else if (!strncmp(buf, "online_movable", min_t(int, count, 14)))
 331                 online_type = ONLINE_MOVABLE;
 332         else if (!strncmp(buf, "online", min_t(int, count, 6)))
 333                 online_type = ONLINE_KEEP;
 334         else if (!strncmp(buf, "offline", min_t(int, count, 7)))
 335                 online_type = -1;
 336         else
 337                 return -EINVAL;
 338
 339         switch (online_type) {
 340         case ONLINE_KERNEL:
 341         case ONLINE_MOVABLE:
 342         case ONLINE_KEEP:
 343                 /*
 344                  * mem->online_type is not protected so there can be a
 345                  * race here.  However, when racing online, the first
 346                  * will succeed and the second will just return as the
 347                  * block will already be online.  The online type
 348                  * could be either one, but that is expected.
 349                  */
 350                 mem->online_type = online_type;
 351                 ret = device_online(&mem->dev);
 352                 break;
 353         case -1:
 354                 ret = device_offline(&mem->dev);
 355                 break;
 356         default:
 357                 ret = -EINVAL; /* should never happen */
 358         }
 359
 360         unlock_device_hotplug();
 361
 362         if (ret)
 363                 return ret;
 364         return count;
 365 }
 366
 367 /*
 368  * phys_device is a bad name for this.  What I really want
 369  * is a way to differentiate between memory ranges that
 370  * are part of physical devices that constitute
 371  * a complete removable unit or fru.
 372  * i.e. do these ranges belong to the same physical device,
 373  * s.t. if I offline all of these sections I can then
 374  * remove the physical device?
 375  */
 376 static ssize_t show_phys_device(struct device *dev,
 377                                 struct device_attribute *attr, char *buf)
 378 {
 379         struct memory_block *mem = to_memory_block(dev);
 380         return sprintf(buf, "%d\n", mem->phys_device);
 381 }
 382
 383 static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
 384 static DEVICE_ATTR(end_phys_index, 0444, show_mem_end_phys_index, NULL);
 385 static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
 386 static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
 387 static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
 388
 389 /*
 390  * Block size attribute stuff
 391  */
 392 static ssize_t
 393 print_block_size(struct device *dev, struct device_attribute *attr,
 394                  char *buf)
 395 {
 396         return sprintf(buf, "%lx\n", get_memory_block_size());
 397 }
 398
 399 static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
 400
 401 /*
 402  * Some architectures will have custom drivers to do this, and
 403  * will not need to do it from userspace.  The fake hot-add code
 404  * as well as ppc64 will do all of their discovery in userspace
 405  * and will require this interface.
 406  */
 407 #ifdef CONFIG_ARCH_MEMORY_PROBE
 408 static ssize_t
 409 memory_probe_store(struct device *dev, struct device_attribute *attr,
 410                    const char *buf, size_t count)
 411 {
 412         u64 phys_addr;
 413         int nid;
 414         int i, ret;
 415         unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
 416
 417         phys_addr = simple_strtoull(buf, NULL, 0);
 418
 419         if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
 420                 return -EINVAL;
 421
 422         for (i = 0; i < sections_per_block; i++) {
 423                 nid = memory_add_physaddr_to_nid(phys_addr);
 424                 ret = add_memory(nid, phys_addr,
 425                                  PAGES_PER_SECTION << PAGE_SHIFT);
 426                 if (ret)
 427                         goto out;
 428
 429                 phys_addr += MIN_MEMORY_BLOCK_SIZE;
 430         }
 431
 432         ret = count;
 433 out:
 434         return ret;
 435 }
 436
 437 static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
 438 #endif
 439
 440 #ifdef CONFIG_MEMORY_FAILURE
 441 /*
 442  * Support for offlining pages of memory
 443  */
 444
 445 /* Soft offline a page */
 446 static ssize_t
 447 store_soft_offline_page(struct device *dev,
 448                         struct device_attribute *attr,
 449                         const char *buf, size_t count)
 450 {
 451         int ret;
 452         u64 pfn;
 453         if (!capable(CAP_SYS_ADMIN))
 454                 return -EPERM;
 455         if (kstrtoull(buf, 0, &pfn) < 0)
 456                 return -EINVAL;
 457         pfn >>= PAGE_SHIFT;
 458         if (!pfn_valid(pfn))
 459                 return -ENXIO;
 460         ret = soft_offline_page(pfn_to_page(pfn), 0);
 461         return ret == 0 ? count : ret;
 462 }
 463
 464 /* Forcibly offline a page, including killing processes. */
 465 static ssize_t
 466 store_hard_offline_page(struct device *dev,
 467                         struct device_attribute *attr,
 468                         const char *buf, size_t count)
 469 {
 470         int ret;
 471         u64 pfn;
 472         if (!capable(CAP_SYS_ADMIN))
 473                 return -EPERM;
 474         if (kstrtoull(buf, 0, &pfn) < 0)
 475                 return -EINVAL;
 476         pfn >>= PAGE_SHIFT;
 477         ret = memory_failure(pfn, 0, 0);
 478         return ret ? ret : count;
 479 }
 480
 481 static DEVICE_ATTR(soft_offline_page, S_IWUSR, NULL, store_soft_offline_page);
 482 static DEVICE_ATTR(hard_offline_page, S_IWUSR, NULL, store_hard_offline_page);
 483 #endif
 484
 485 /*
 486  * Note that phys_device is optional.  It is here to allow for
 487  * differentiation between which *physical* devices each
 488  * section belongs to...
 489  */
 490 int __weak arch_get_memory_phys_device(unsigned long start_pfn)
 491 {
 492         return 0;
 493 }
 494
 495 /*
 496  * A reference for the returned object is held and the reference for the
 497  * hinted object is released.
 498  */
 499 struct memory_block *find_memory_block_hinted(struct mem_section *section,
 500                                               struct memory_block *hint)
 501 {
 502         int block_id = base_memory_block_id(__section_nr(section));
 503         struct device *hintdev = hint ? &hint->dev : NULL;
 504         struct device *dev;
 505
 506         dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev);
 507         if (hint)
 508                 put_device(&hint->dev);
 509         if (!dev)
 510                 return NULL;
 511         return to_memory_block(dev);
 512 }
 513
 514 /*
 515  * For now, we have a linear search to go find the appropriate
 516  * memory_block corresponding to a particular phys_index. If
 517  * this gets to be a real problem, we can always use a radix
 518  * tree or something here.
 519  *
 520  * This could be made generic for all device subsystems.
 521  */
 522 struct memory_block *find_memory_block(struct mem_section *section)
 523 {
 524         return find_memory_block_hinted(section, NULL);
 525 }
 526
 527 static struct attribute *memory_memblk_attrs[] = {
 528         &dev_attr_phys_index.attr,
 529         &dev_attr_end_phys_index.attr,
 530         &dev_attr_state.attr,
 531         &dev_attr_phys_device.attr,
 532         &dev_attr_removable.attr,
 533         NULL
 534 };
 535
 536 static struct attribute_group memory_memblk_attr_group = {
 537         .attrs = memory_memblk_attrs,
 538 };
 539
 540 static const struct attribute_group *memory_memblk_attr_groups[] = {
 541         &memory_memblk_attr_group,
 542         NULL,
 543 };
 544
 545 /*
 546  * register_memory - Setup a sysfs device for a memory block
 547  */
 548 static
 549 int register_memory(struct memory_block *memory)
 550 {
 551         memory->dev.bus = &memory_subsys;
 552         memory->dev.id = memory->start_section_nr / sections_per_block;
 553         memory->dev.release = memory_block_release;
 554         memory->dev.groups = memory_memblk_attr_groups;
 555         memory->dev.offline = memory->state == MEM_OFFLINE;
 556
 557         return device_register(&memory->dev);
 558 }
 559
 560 static int init_memory_block(struct memory_block **memory,
 561                              struct mem_section *section, unsigned long state)
 562 {
 563         struct memory_block *mem;
 564         unsigned long start_pfn;
 565         int scn_nr;
 566         int ret = 0;
 567
 568         mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 569         if (!mem)
 570                 return -ENOMEM;
 571
 572         scn_nr = __section_nr(section);
 573         mem->start_section_nr =
 574                         base_memory_block_id(scn_nr) * sections_per_block;
 575         mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
 576         mem->state = state;
 577         mem->section_count++;
 578         start_pfn = section_nr_to_pfn(mem->start_section_nr);
 579         mem->phys_device = arch_get_memory_phys_device(start_pfn);
 580
 581         ret = register_memory(mem);
 582
 583         *memory = mem;
 584         return ret;
 585 }
 586
 587 static int add_memory_block(int base_section_nr)
 588 {
 589         struct memory_block *mem;
 590         int i, ret, section_count = 0, section_nr;
 591
 592         for (i = base_section_nr;
 593              (i < base_section_nr + sections_per_block) && i < NR_MEM_SECTIONS;
 594              i++) {
 595                 if (!present_section_nr(i))
 596                         continue;
 597                 if (section_count == 0)
 598                         section_nr = i;
 599                 section_count++;
 600         }
 601
 602         if (section_count == 0)
 603                 return 0;
 604         ret = init_memory_block(&mem, __nr_to_section(section_nr), MEM_ONLINE);
 605         if (ret)
 606                 return ret;
 607         mem->section_count = section_count;
 608         return 0;
 609 }
 610
 611
 612 /*
 613  * need an interface for the VM to add new memory regions,
 614  * but without onlining it.
 615  */
 616 int register_new_memory(int nid, struct mem_section *section)
 617 {
 618         int ret = 0;
 619         struct memory_block *mem;
 620
 621         mutex_lock(&mem_sysfs_mutex);
 622
 623         mem = find_memory_block(section);
 624         if (mem) {
 625                 mem->section_count++;
 626                 put_device(&mem->dev);
 627         } else {
 628                 ret = init_memory_block(&mem, section, MEM_OFFLINE);
 629                 if (ret)
 630                         goto out;
 631         }
 632
 633         if (mem->section_count == sections_per_block)
 634                 ret = register_mem_sect_under_node(mem, nid);
 635 out:
 636         mutex_unlock(&mem_sysfs_mutex);
 637         return ret;
 638 }
 639
 640 #ifdef CONFIG_MEMORY_HOTREMOVE
 641 static void
 642 unregister_memory(struct memory_block *memory)
 643 {
 644         BUG_ON(memory->dev.bus != &memory_subsys);
 645
 646         /* drop the ref. we got in remove_memory_block() */
 647         put_device(&memory->dev);
 648         device_unregister(&memory->dev);
 649 }
 650
 651 static int remove_memory_block(unsigned long node_id,
 652                                struct mem_section *section, int phys_device)
 653 {
 654         struct memory_block *mem;
 655
 656         mutex_lock(&mem_sysfs_mutex);
 657         mem = find_memory_block(section);
 658         unregister_mem_sect_under_nodes(mem, __section_nr(section));
 659
 660         mem->section_count--;
 661         if (mem->section_count == 0)
 662                 unregister_memory(mem);
 663         else
 664                 put_device(&mem->dev);
 665
 666         mutex_unlock(&mem_sysfs_mutex);
 667         return 0;
 668 }
 669
 670 int unregister_memory_section(struct mem_section *section)
 671 {
 672         if (!present_section(section))
 673                 return -EINVAL;
 674
 675         return remove_memory_block(0, section, 0);
 676 }
 677 #endif /* CONFIG_MEMORY_HOTREMOVE */
 678
 679 /* return true if the memory block is offlined, otherwise, return false */
 680 bool is_memblock_offlined(struct memory_block *mem)
 681 {
 682         return mem->state == MEM_OFFLINE;
 683 }
 684
 685 static struct attribute *memory_root_attrs[] = {
 686 #ifdef CONFIG_ARCH_MEMORY_PROBE
 687         &dev_attr_probe.attr,
 688 #endif
 689
 690 #ifdef CONFIG_MEMORY_FAILURE
 691         &dev_attr_soft_offline_page.attr,
 692         &dev_attr_hard_offline_page.attr,
 693 #endif
 694
 695         &dev_attr_block_size_bytes.attr,
 696         NULL
 697 };
 698
 699 static struct attribute_group memory_root_attr_group = {
 700         .attrs = memory_root_attrs,
 701 };
 702
 703 static const struct attribute_group *memory_root_attr_groups[] = {
 704         &memory_root_attr_group,
 705         NULL,
 706 };
 707
 708 /*
 709  * Initialize the sysfs support for memory devices...
 710  */
 711 int __init memory_dev_init(void)
 712 {
 713         unsigned int i;
 714         int ret;
 715         int err;
 716         unsigned long block_sz;
 717
 718         ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
 719         if (ret)
 720                 goto out;
 721
 722         block_sz = get_memory_block_size();
 723         sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
 724
 725         /*
 726          * Create entries for memory sections that were found
 727          * during boot and have been initialized
 728          */
 729         mutex_lock(&mem_sysfs_mutex);
 730         for (i = 0; i < NR_MEM_SECTIONS; i += sections_per_block) {
 731                 err = add_memory_block(i);
 732                 if (!ret)
 733                         ret = err;
 734         }
 735         mutex_unlock(&mem_sysfs_mutex);
 736
 737 out:
 738         if (ret)
 739                 printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
 740         return ret;
 741 }