linux/drivers/base/memory.c
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   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/kobject.h>
  20#include <linux/memory_hotplug.h>
  21#include <linux/mm.h>
  22#include <linux/mutex.h>
  23#include <linux/stat.h>
  24#include <linux/slab.h>
  25
  26#include <linux/atomic.h>
  27#include <asm/uaccess.h>
  28
  29static DEFINE_MUTEX(mem_sysfs_mutex);
  30
  31#define MEMORY_CLASS_NAME       "memory"
  32
  33static int sections_per_block;
  34
  35static inline int base_memory_block_id(int section_nr)
  36{
  37        return section_nr / sections_per_block;
  38}
  39
  40static int memory_subsys_online(struct device *dev);
  41static int memory_subsys_offline(struct device *dev);
  42
  43static struct bus_type memory_subsys = {
  44        .name = MEMORY_CLASS_NAME,
  45        .dev_name = MEMORY_CLASS_NAME,
  46        .online = memory_subsys_online,
  47        .offline = memory_subsys_offline,
  48};
  49
  50static BLOCKING_NOTIFIER_HEAD(memory_chain);
  51
  52int register_memory_notifier(struct notifier_block *nb)
  53{
  54        return blocking_notifier_chain_register(&memory_chain, nb);
  55}
  56EXPORT_SYMBOL(register_memory_notifier);
  57
  58void unregister_memory_notifier(struct notifier_block *nb)
  59{
  60        blocking_notifier_chain_unregister(&memory_chain, nb);
  61}
  62EXPORT_SYMBOL(unregister_memory_notifier);
  63
  64static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
  65
  66int register_memory_isolate_notifier(struct notifier_block *nb)
  67{
  68        return atomic_notifier_chain_register(&memory_isolate_chain, nb);
  69}
  70EXPORT_SYMBOL(register_memory_isolate_notifier);
  71
  72void unregister_memory_isolate_notifier(struct notifier_block *nb)
  73{
  74        atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
  75}
  76EXPORT_SYMBOL(unregister_memory_isolate_notifier);
  77
  78static void memory_block_release(struct device *dev)
  79{
  80        struct memory_block *mem = container_of(dev, struct memory_block, dev);
  81
  82        kfree(mem);
  83}
  84
  85unsigned long __weak memory_block_size_bytes(void)
  86{
  87        return MIN_MEMORY_BLOCK_SIZE;
  88}
  89
  90static unsigned long get_memory_block_size(void)
  91{
  92        unsigned long block_sz;
  93
  94        block_sz = memory_block_size_bytes();
  95
  96        /* Validate blk_sz is a power of 2 and not less than section size */
  97        if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE)) {
  98                WARN_ON(1);
  99                block_sz = MIN_MEMORY_BLOCK_SIZE;
 100        }
 101
 102        return block_sz;
 103}
 104
 105/*
 106 * use this as the physical section index that this memsection
 107 * uses.
 108 */
 109
 110static ssize_t show_mem_start_phys_index(struct device *dev,
 111                        struct device_attribute *attr, char *buf)
 112{
 113        struct memory_block *mem =
 114                container_of(dev, struct 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
 121static ssize_t show_mem_end_phys_index(struct device *dev,
 122                        struct device_attribute *attr, char *buf)
 123{
 124        struct memory_block *mem =
 125                container_of(dev, struct memory_block, dev);
 126        unsigned long phys_index;
 127
 128        phys_index = mem->end_section_nr / sections_per_block;
 129        return sprintf(buf, "%08lx\n", phys_index);
 130}
 131
 132/*
 133 * Show whether the section of memory is likely to be hot-removable
 134 */
 135static ssize_t show_mem_removable(struct device *dev,
 136                        struct device_attribute *attr, char *buf)
 137{
 138        unsigned long i, pfn;
 139        int ret = 1;
 140        struct memory_block *mem =
 141                container_of(dev, struct memory_block, dev);
 142
 143        for (i = 0; i < sections_per_block; i++) {
 144                if (!present_section_nr(mem->start_section_nr + i))
 145                        continue;
 146                pfn = section_nr_to_pfn(mem->start_section_nr + i);
 147                ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
 148        }
 149
 150        return sprintf(buf, "%d\n", ret);
 151}
 152
 153/*
 154 * online, offline, going offline, etc.
 155 */
 156static ssize_t show_mem_state(struct device *dev,
 157                        struct device_attribute *attr, char *buf)
 158{
 159        struct memory_block *mem =
 160                container_of(dev, struct memory_block, dev);
 161        ssize_t len = 0;
 162
 163        /*
 164         * We can probably put these states in a nice little array
 165         * so that they're not open-coded
 166         */
 167        switch (mem->state) {
 168                case MEM_ONLINE:
 169                        len = sprintf(buf, "online\n");
 170                        break;
 171                case MEM_OFFLINE:
 172                        len = sprintf(buf, "offline\n");
 173                        break;
 174                case MEM_GOING_OFFLINE:
 175                        len = sprintf(buf, "going-offline\n");
 176                        break;
 177                default:
 178                        len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
 179                                        mem->state);
 180                        WARN_ON(1);
 181                        break;
 182        }
 183
 184        return len;
 185}
 186
 187int memory_notify(unsigned long val, void *v)
 188{
 189        return blocking_notifier_call_chain(&memory_chain, val, v);
 190}
 191
 192int memory_isolate_notify(unsigned long val, void *v)
 193{
 194        return atomic_notifier_call_chain(&memory_isolate_chain, val, v);
 195}
 196
 197/*
 198 * The probe routines leave the pages reserved, just as the bootmem code does.
 199 * Make sure they're still that way.
 200 */
 201static bool pages_correctly_reserved(unsigned long start_pfn)
 202{
 203        int i, j;
 204        struct page *page;
 205        unsigned long pfn = start_pfn;
 206
 207        /*
 208         * memmap between sections is not contiguous except with
 209         * SPARSEMEM_VMEMMAP. We lookup the page once per section
 210         * and assume memmap is contiguous within each section
 211         */
 212        for (i = 0; i < sections_per_block; i++, pfn += PAGES_PER_SECTION) {
 213                if (WARN_ON_ONCE(!pfn_valid(pfn)))
 214                        return false;
 215                page = pfn_to_page(pfn);
 216
 217                for (j = 0; j < PAGES_PER_SECTION; j++) {
 218                        if (PageReserved(page + j))
 219                                continue;
 220
 221                        printk(KERN_WARNING "section number %ld page number %d "
 222                                "not reserved, was it already online?\n",
 223                                pfn_to_section_nr(pfn), j);
 224
 225                        return false;
 226                }
 227        }
 228
 229        return true;
 230}
 231
 232/*
 233 * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
 234 * OK to have direct references to sparsemem variables in here.
 235 */
 236static int
 237memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
 238{
 239        unsigned long start_pfn;
 240        unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
 241        struct page *first_page;
 242        int ret;
 243
 244        first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
 245        start_pfn = page_to_pfn(first_page);
 246
 247        switch (action) {
 248                case MEM_ONLINE:
 249                        if (!pages_correctly_reserved(start_pfn))
 250                                return -EBUSY;
 251
 252                        ret = online_pages(start_pfn, nr_pages, online_type);
 253                        break;
 254                case MEM_OFFLINE:
 255                        ret = offline_pages(start_pfn, nr_pages);
 256                        break;
 257                default:
 258                        WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
 259                             "%ld\n", __func__, phys_index, action, action);
 260                        ret = -EINVAL;
 261        }
 262
 263        return ret;
 264}
 265
 266static int __memory_block_change_state(struct memory_block *mem,
 267                unsigned long to_state, unsigned long from_state_req,
 268                int online_type)
 269{
 270        int ret = 0;
 271
 272        if (mem->state != from_state_req)
 273                return -EINVAL;
 274
 275        if (to_state == MEM_OFFLINE)
 276                mem->state = MEM_GOING_OFFLINE;
 277
 278        ret = memory_block_action(mem->start_section_nr, to_state, online_type);
 279        mem->state = ret ? from_state_req : to_state;
 280        return ret;
 281}
 282
 283static int memory_subsys_online(struct device *dev)
 284{
 285        struct memory_block *mem = container_of(dev, struct memory_block, dev);
 286        int ret;
 287
 288        mutex_lock(&mem->state_mutex);
 289
 290        ret = mem->state == MEM_ONLINE ? 0 :
 291                __memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE,
 292                                            ONLINE_KEEP);
 293
 294        mutex_unlock(&mem->state_mutex);
 295        return ret;
 296}
 297
 298static int memory_subsys_offline(struct device *dev)
 299{
 300        struct memory_block *mem = container_of(dev, struct memory_block, dev);
 301        int ret;
 302
 303        mutex_lock(&mem->state_mutex);
 304
 305        ret = mem->state == MEM_OFFLINE ? 0 :
 306                __memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE, -1);
 307
 308        mutex_unlock(&mem->state_mutex);
 309        return ret;
 310}
 311
 312static int __memory_block_change_state_uevent(struct memory_block *mem,
 313                unsigned long to_state, unsigned long from_state_req,
 314                int online_type)
 315{
 316        int ret = __memory_block_change_state(mem, to_state, from_state_req,
 317                                              online_type);
 318        if (!ret) {
 319                switch (mem->state) {
 320                case MEM_OFFLINE:
 321                        kobject_uevent(&mem->dev.kobj, KOBJ_OFFLINE);
 322                        break;
 323                case MEM_ONLINE:
 324                        kobject_uevent(&mem->dev.kobj, KOBJ_ONLINE);
 325                        break;
 326                default:
 327                        break;
 328                }
 329        }
 330        return ret;
 331}
 332
 333static int memory_block_change_state(struct memory_block *mem,
 334                unsigned long to_state, unsigned long from_state_req,
 335                int online_type)
 336{
 337        int ret;
 338
 339        mutex_lock(&mem->state_mutex);
 340        ret = __memory_block_change_state_uevent(mem, to_state, from_state_req,
 341                                                 online_type);
 342        mutex_unlock(&mem->state_mutex);
 343
 344        return ret;
 345}
 346static ssize_t
 347store_mem_state(struct device *dev,
 348                struct device_attribute *attr, const char *buf, size_t count)
 349{
 350        struct memory_block *mem;
 351        bool offline;
 352        int ret = -EINVAL;
 353
 354        mem = container_of(dev, struct memory_block, dev);
 355
 356        lock_device_hotplug();
 357
 358        if (!strncmp(buf, "online_kernel", min_t(int, count, 13))) {
 359                offline = false;
 360                ret = memory_block_change_state(mem, MEM_ONLINE,
 361                                                MEM_OFFLINE, ONLINE_KERNEL);
 362        } else if (!strncmp(buf, "online_movable", min_t(int, count, 14))) {
 363                offline = false;
 364                ret = memory_block_change_state(mem, MEM_ONLINE,
 365                                                MEM_OFFLINE, ONLINE_MOVABLE);
 366        } else if (!strncmp(buf, "online", min_t(int, count, 6))) {
 367                offline = false;
 368                ret = memory_block_change_state(mem, MEM_ONLINE,
 369                                                MEM_OFFLINE, ONLINE_KEEP);
 370        } else if(!strncmp(buf, "offline", min_t(int, count, 7))) {
 371                offline = true;
 372                ret = memory_block_change_state(mem, MEM_OFFLINE,
 373                                                MEM_ONLINE, -1);
 374        }
 375        if (!ret)
 376                dev->offline = offline;
 377
 378        unlock_device_hotplug();
 379
 380        if (ret)
 381                return ret;
 382        return count;
 383}
 384
 385/*
 386 * phys_device is a bad name for this.  What I really want
 387 * is a way to differentiate between memory ranges that
 388 * are part of physical devices that constitute
 389 * a complete removable unit or fru.
 390 * i.e. do these ranges belong to the same physical device,
 391 * s.t. if I offline all of these sections I can then
 392 * remove the physical device?
 393 */
 394static ssize_t show_phys_device(struct device *dev,
 395                                struct device_attribute *attr, char *buf)
 396{
 397        struct memory_block *mem =
 398                container_of(dev, struct memory_block, dev);
 399        return sprintf(buf, "%d\n", mem->phys_device);
 400}
 401
 402static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
 403static DEVICE_ATTR(end_phys_index, 0444, show_mem_end_phys_index, NULL);
 404static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
 405static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
 406static DEVICE_ATTR(removable, 0444, show_mem_removable, NULL);
 407
 408/*
 409 * Block size attribute stuff
 410 */
 411static ssize_t
 412print_block_size(struct device *dev, struct device_attribute *attr,
 413                 char *buf)
 414{
 415        return sprintf(buf, "%lx\n", get_memory_block_size());
 416}
 417
 418static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
 419
 420/*
 421 * Some architectures will have custom drivers to do this, and
 422 * will not need to do it from userspace.  The fake hot-add code
 423 * as well as ppc64 will do all of their discovery in userspace
 424 * and will require this interface.
 425 */
 426#ifdef CONFIG_ARCH_MEMORY_PROBE
 427static ssize_t
 428memory_probe_store(struct device *dev, struct device_attribute *attr,
 429                   const char *buf, size_t count)
 430{
 431        u64 phys_addr;
 432        int nid;
 433        int i, ret;
 434        unsigned long pages_per_block = PAGES_PER_SECTION * sections_per_block;
 435
 436        phys_addr = simple_strtoull(buf, NULL, 0);
 437
 438        if (phys_addr & ((pages_per_block << PAGE_SHIFT) - 1))
 439                return -EINVAL;
 440
 441        for (i = 0; i < sections_per_block; i++) {
 442                nid = memory_add_physaddr_to_nid(phys_addr);
 443                ret = add_memory(nid, phys_addr,
 444                                 PAGES_PER_SECTION << PAGE_SHIFT);
 445                if (ret)
 446                        goto out;
 447
 448                phys_addr += MIN_MEMORY_BLOCK_SIZE;
 449        }
 450
 451        ret = count;
 452out:
 453        return ret;
 454}
 455
 456static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
 457#endif
 458
 459#ifdef CONFIG_MEMORY_FAILURE
 460/*
 461 * Support for offlining pages of memory
 462 */
 463
 464/* Soft offline a page */
 465static ssize_t
 466store_soft_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 (strict_strtoull(buf, 0, &pfn) < 0)
 475                return -EINVAL;
 476        pfn >>= PAGE_SHIFT;
 477        if (!pfn_valid(pfn))
 478                return -ENXIO;
 479        ret = soft_offline_page(pfn_to_page(pfn), 0);
 480        return ret == 0 ? count : ret;
 481}
 482
 483/* Forcibly offline a page, including killing processes. */
 484static ssize_t
 485store_hard_offline_page(struct device *dev,
 486                        struct device_attribute *attr,
 487                        const char *buf, size_t count)
 488{
 489        int ret;
 490        u64 pfn;
 491        if (!capable(CAP_SYS_ADMIN))
 492                return -EPERM;
 493        if (strict_strtoull(buf, 0, &pfn) < 0)
 494                return -EINVAL;
 495        pfn >>= PAGE_SHIFT;
 496        ret = memory_failure(pfn, 0, 0);
 497        return ret ? ret : count;
 498}
 499
 500static DEVICE_ATTR(soft_offline_page, S_IWUSR, NULL, store_soft_offline_page);
 501static DEVICE_ATTR(hard_offline_page, S_IWUSR, NULL, store_hard_offline_page);
 502#endif
 503
 504/*
 505 * Note that phys_device is optional.  It is here to allow for
 506 * differentiation between which *physical* devices each
 507 * section belongs to...
 508 */
 509int __weak arch_get_memory_phys_device(unsigned long start_pfn)
 510{
 511        return 0;
 512}
 513
 514/*
 515 * A reference for the returned object is held and the reference for the
 516 * hinted object is released.
 517 */
 518struct memory_block *find_memory_block_hinted(struct mem_section *section,
 519                                              struct memory_block *hint)
 520{
 521        int block_id = base_memory_block_id(__section_nr(section));
 522        struct device *hintdev = hint ? &hint->dev : NULL;
 523        struct device *dev;
 524
 525        dev = subsys_find_device_by_id(&memory_subsys, block_id, hintdev);
 526        if (hint)
 527                put_device(&hint->dev);
 528        if (!dev)
 529                return NULL;
 530        return container_of(dev, struct memory_block, dev);
 531}
 532
 533/*
 534 * For now, we have a linear search to go find the appropriate
 535 * memory_block corresponding to a particular phys_index. If
 536 * this gets to be a real problem, we can always use a radix
 537 * tree or something here.
 538 *
 539 * This could be made generic for all device subsystems.
 540 */
 541struct memory_block *find_memory_block(struct mem_section *section)
 542{
 543        return find_memory_block_hinted(section, NULL);
 544}
 545
 546static struct attribute *memory_memblk_attrs[] = {
 547        &dev_attr_phys_index.attr,
 548        &dev_attr_end_phys_index.attr,
 549        &dev_attr_state.attr,
 550        &dev_attr_phys_device.attr,
 551        &dev_attr_removable.attr,
 552        NULL
 553};
 554
 555static struct attribute_group memory_memblk_attr_group = {
 556        .attrs = memory_memblk_attrs,
 557};
 558
 559static const struct attribute_group *memory_memblk_attr_groups[] = {
 560        &memory_memblk_attr_group,
 561        NULL,
 562};
 563
 564/*
 565 * register_memory - Setup a sysfs device for a memory block
 566 */
 567static
 568int register_memory(struct memory_block *memory)
 569{
 570        int error;
 571
 572        memory->dev.bus = &memory_subsys;
 573        memory->dev.id = memory->start_section_nr / sections_per_block;
 574        memory->dev.release = memory_block_release;
 575        memory->dev.groups = memory_memblk_attr_groups;
 576        memory->dev.offline = memory->state == MEM_OFFLINE;
 577
 578        error = device_register(&memory->dev);
 579        return error;
 580}
 581
 582static int init_memory_block(struct memory_block **memory,
 583                             struct mem_section *section, unsigned long state)
 584{
 585        struct memory_block *mem;
 586        unsigned long start_pfn;
 587        int scn_nr;
 588        int ret = 0;
 589
 590        mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 591        if (!mem)
 592                return -ENOMEM;
 593
 594        scn_nr = __section_nr(section);
 595        mem->start_section_nr =
 596                        base_memory_block_id(scn_nr) * sections_per_block;
 597        mem->end_section_nr = mem->start_section_nr + sections_per_block - 1;
 598        mem->state = state;
 599        mem->section_count++;
 600        mutex_init(&mem->state_mutex);
 601        start_pfn = section_nr_to_pfn(mem->start_section_nr);
 602        mem->phys_device = arch_get_memory_phys_device(start_pfn);
 603
 604        ret = register_memory(mem);
 605
 606        *memory = mem;
 607        return ret;
 608}
 609
 610static int add_memory_section(int nid, struct mem_section *section,
 611                        struct memory_block **mem_p,
 612                        unsigned long state, enum mem_add_context context)
 613{
 614        struct memory_block *mem = NULL;
 615        int scn_nr = __section_nr(section);
 616        int ret = 0;
 617
 618        mutex_lock(&mem_sysfs_mutex);
 619
 620        if (context == BOOT) {
 621                /* same memory block ? */
 622                if (mem_p && *mem_p)
 623                        if (scn_nr >= (*mem_p)->start_section_nr &&
 624                            scn_nr <= (*mem_p)->end_section_nr) {
 625                                mem = *mem_p;
 626                                kobject_get(&mem->dev.kobj);
 627                        }
 628        } else
 629                mem = find_memory_block(section);
 630
 631        if (mem) {
 632                mem->section_count++;
 633                kobject_put(&mem->dev.kobj);
 634        } else {
 635                ret = init_memory_block(&mem, section, state);
 636                /* store memory_block pointer for next loop */
 637                if (!ret && context == BOOT)
 638                        if (mem_p)
 639                                *mem_p = mem;
 640        }
 641
 642        if (!ret) {
 643                if (context == HOTPLUG &&
 644                    mem->section_count == sections_per_block)
 645                        ret = register_mem_sect_under_node(mem, nid);
 646        }
 647
 648        mutex_unlock(&mem_sysfs_mutex);
 649        return ret;
 650}
 651
 652/*
 653 * need an interface for the VM to add new memory regions,
 654 * but without onlining it.
 655 */
 656int register_new_memory(int nid, struct mem_section *section)
 657{
 658        return add_memory_section(nid, section, NULL, MEM_OFFLINE, HOTPLUG);
 659}
 660
 661#ifdef CONFIG_MEMORY_HOTREMOVE
 662static void
 663unregister_memory(struct memory_block *memory)
 664{
 665        BUG_ON(memory->dev.bus != &memory_subsys);
 666
 667        /* drop the ref. we got in remove_memory_block() */
 668        kobject_put(&memory->dev.kobj);
 669        device_unregister(&memory->dev);
 670}
 671
 672static int remove_memory_block(unsigned long node_id,
 673                               struct mem_section *section, int phys_device)
 674{
 675        struct memory_block *mem;
 676
 677        mutex_lock(&mem_sysfs_mutex);
 678        mem = find_memory_block(section);
 679        unregister_mem_sect_under_nodes(mem, __section_nr(section));
 680
 681        mem->section_count--;
 682        if (mem->section_count == 0)
 683                unregister_memory(mem);
 684        else
 685                kobject_put(&mem->dev.kobj);
 686
 687        mutex_unlock(&mem_sysfs_mutex);
 688        return 0;
 689}
 690
 691int unregister_memory_section(struct mem_section *section)
 692{
 693        if (!present_section(section))
 694                return -EINVAL;
 695
 696        return remove_memory_block(0, section, 0);
 697}
 698#endif /* CONFIG_MEMORY_HOTREMOVE */
 699
 700/* return true if the memory block is offlined, otherwise, return false */
 701bool is_memblock_offlined(struct memory_block *mem)
 702{
 703        return mem->state == MEM_OFFLINE;
 704}
 705
 706static struct attribute *memory_root_attrs[] = {
 707#ifdef CONFIG_ARCH_MEMORY_PROBE
 708        &dev_attr_probe.attr,
 709#endif
 710
 711#ifdef CONFIG_MEMORY_FAILURE
 712        &dev_attr_soft_offline_page.attr,
 713        &dev_attr_hard_offline_page.attr,
 714#endif
 715
 716        &dev_attr_block_size_bytes.attr,
 717        NULL
 718};
 719
 720static struct attribute_group memory_root_attr_group = {
 721        .attrs = memory_root_attrs,
 722};
 723
 724static const struct attribute_group *memory_root_attr_groups[] = {
 725        &memory_root_attr_group,
 726        NULL,
 727};
 728
 729/*
 730 * Initialize the sysfs support for memory devices...
 731 */
 732int __init memory_dev_init(void)
 733{
 734        unsigned int i;
 735        int ret;
 736        int err;
 737        unsigned long block_sz;
 738        struct memory_block *mem = NULL;
 739
 740        ret = subsys_system_register(&memory_subsys, memory_root_attr_groups);
 741        if (ret)
 742                goto out;
 743
 744        block_sz = get_memory_block_size();
 745        sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
 746
 747        /*
 748         * Create entries for memory sections that were found
 749         * during boot and have been initialized
 750         */
 751        for (i = 0; i < NR_MEM_SECTIONS; i++) {
 752                if (!present_section_nr(i))
 753                        continue;
 754                /* don't need to reuse memory_block if only one per block */
 755                err = add_memory_section(0, __nr_to_section(i),
 756                                 (sections_per_block == 1) ? NULL : &mem,
 757                                         MEM_ONLINE,
 758                                         BOOT);
 759                if (!ret)
 760                        ret = err;
 761        }
 762
 763out:
 764        if (ret)
 765                printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
 766        return ret;
 767}
 768
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