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/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
  29 static DEFINE_MUTEX(mem_sysfs_mutex);
  30
  31 #define MEMORY_CLASS_NAME       "memory"
  32
  33 static int sections_per_block;
  34
  35 static inline int base_memory_block_id(int section_nr)
  36 {
  37         return section_nr / sections_per_block;
  38 }
  39
  40 static struct bus_type memory_subsys = {
  41         .name = MEMORY_CLASS_NAME,
  42         .dev_name = MEMORY_CLASS_NAME,
  43 };
  44
  45 static BLOCKING_NOTIFIER_HEAD(memory_chain);
  46
  47 int register_memory_notifier(struct notifier_block *nb)
  48 {
  49         return blocking_notifier_chain_register(&memory_chain, nb);
  50 }
  51 EXPORT_SYMBOL(register_memory_notifier);
  52
  53 void unregister_memory_notifier(struct notifier_block *nb)
  54 {
  55         blocking_notifier_chain_unregister(&memory_chain, nb);
  56 }
  57 EXPORT_SYMBOL(unregister_memory_notifier);
  58
  59 static ATOMIC_NOTIFIER_HEAD(memory_isolate_chain);
  60
  61 int register_memory_isolate_notifier(struct notifier_block *nb)
  62 {
  63         return atomic_notifier_chain_register(&memory_isolate_chain, nb);
  64 }
  65 EXPORT_SYMBOL(register_memory_isolate_notifier);
  66
  67 void unregister_memory_isolate_notifier(struct notifier_block *nb)
  68 {
  69         atomic_notifier_chain_unregister(&memory_isolate_chain, nb);
  70 }
  71 EXPORT_SYMBOL(unregister_memory_isolate_notifier);
  72
  73 /*
  74  * register_memory - Setup a sysfs device for a memory block
  75  */
  76 static
  77 int 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
  88 static void
  89 unregister_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
  98 unsigned long __weak memory_block_size_bytes(void)
  99 {
 100         return MIN_MEMORY_BLOCK_SIZE;
 101 }
 102
 103 static 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
 123 static 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
 134 static 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  */
 148 static 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  */
 167 static 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
 198 int memory_notify(unsigned long val, void *v)
 199 {
 200         return blocking_notifier_call_chain(&memory_chain, val, v);
 201 }
 202
 203 int 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  */
 212 static 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  */
 248 static int
 249 memory_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
 281 static 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         }
 314 out:
 315         mutex_unlock(&mem->state_mutex);
 316         return ret;
 317 }
 318
 319 static ssize_t
 320 store_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  */
 347 static 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
 355 static DEVICE_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
 356 static DEVICE_ATTR(end_phys_index, 0444, show_mem_end_phys_index, NULL);
 357 static DEVICE_ATTR(state, 0644, show_mem_state, store_mem_state);
 358 static DEVICE_ATTR(phys_device, 0444, show_phys_device, NULL);
 359 static 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  */
 369 static ssize_t
 370 print_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
 376 static DEVICE_ATTR(block_size_bytes, 0444, print_block_size, NULL);
 377
 378 static 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
 391 static ssize_t
 392 memory_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;
 416 out:
 417         return ret;
 418 }
 419 static DEVICE_ATTR(probe, S_IWUSR, NULL, memory_probe_store);
 420
 421 static int memory_probe_init(void)
 422 {
 423         return device_create_file(memory_subsys.dev_root, &dev_attr_probe);
 424 }
 425 #else
 426 static 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 */
 438 static ssize_t
 439 store_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. */
 457 static ssize_t
 458 store_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
 473 static DEVICE_ATTR(soft_offline_page, 0644, NULL, store_soft_offline_page);
 474 static DEVICE_ATTR(hard_offline_page, 0644, NULL, store_hard_offline_page);
 475
 476 static __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
 488 static 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  */
 499 int __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  */
 508 struct 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  */
 531 struct memory_block *find_memory_block(struct mem_section *section)
 532 {
 533         return find_memory_block_hinted(section, NULL);
 534 }
 535
 536 static 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
 574 static 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
 616 int 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  */
 645 int register_new_memory(int nid, struct mem_section *section)
 646 {
 647         return add_memory_section(nid, section, NULL, MEM_OFFLINE, HOTPLUG);
 648 }
 649
 650 int 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  */
 661 int __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;
 701 out:
 702         if (ret)
 703                 printk(KERN_ERR "%s() failed: %d\n", __func__, ret);
 704         return ret;
 705 }