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