mm/vmstat.c

   1 /*
   2  *  linux/mm/vmstat.c
   3  *
   4  *  Manages VM statistics
   5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   6  *
   7  *  zoned VM statistics
   8  *  Copyright (C) 2006 Silicon Graphics, Inc.,
   9  *              Christoph Lameter <christoph@lameter.com>
  10  */
  11 #include <linux/fs.h>
  12 #include <linux/mm.h>
  13 #include <linux/err.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/cpu.h>
  17 #include <linux/vmstat.h>
  18 #include <linux/sched.h>
  19 #include <linux/math64.h>
  20 #include <linux/writeback.h>
  21 #include <linux/compaction.h>
  22
  23 #ifdef CONFIG_VM_EVENT_COUNTERS
  24 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
  25 EXPORT_PER_CPU_SYMBOL(vm_event_states);
  26
  27 static void sum_vm_events(unsigned long *ret)
  28 {
  29         int cpu;
  30         int i;
  31
  32         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
  33
  34         for_each_online_cpu(cpu) {
  35                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
  36
  37                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
  38                         ret[i] += this->event[i];
  39         }
  40 }
  41
  42 /*
  43  * Accumulate the vm event counters across all CPUs.
  44  * The result is unavoidably approximate - it can change
  45  * during and after execution of this function.
  46 */
  47 void all_vm_events(unsigned long *ret)
  48 {
  49         get_online_cpus();
  50         sum_vm_events(ret);
  51         put_online_cpus();
  52 }
  53 EXPORT_SYMBOL_GPL(all_vm_events);
  54
  55 #ifdef CONFIG_HOTPLUG
  56 /*
  57  * Fold the foreign cpu events into our own.
  58  *
  59  * This is adding to the events on one processor
  60  * but keeps the global counts constant.
  61  */
  62 void vm_events_fold_cpu(int cpu)
  63 {
  64         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
  65         int i;
  66
  67         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
  68                 count_vm_events(i, fold_state->event[i]);
  69                 fold_state->event[i] = 0;
  70         }
  71 }
  72 #endif /* CONFIG_HOTPLUG */
  73
  74 #endif /* CONFIG_VM_EVENT_COUNTERS */
  75
  76 /*
  77  * Manage combined zone based / global counters
  78  *
  79  * vm_stat contains the global counters
  80  */
  81 atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
  82 EXPORT_SYMBOL(vm_stat);
  83
  84 #ifdef CONFIG_SMP
  85
  86 int calculate_pressure_threshold(struct zone *zone)
  87 {
  88         int threshold;
  89         int watermark_distance;
  90
  91         /*
  92          * As vmstats are not up to date, there is drift between the estimated
  93          * and real values. For high thresholds and a high number of CPUs, it
  94          * is possible for the min watermark to be breached while the estimated
  95          * value looks fine. The pressure threshold is a reduced value such
  96          * that even the maximum amount of drift will not accidentally breach
  97          * the min watermark
  98          */
  99         watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
 100         threshold = max(1, (int)(watermark_distance / num_online_cpus()));
 101
 102         /*
 103          * Maximum threshold is 125
 104          */
 105         threshold = min(125, threshold);
 106
 107         return threshold;
 108 }
 109
 110 int calculate_normal_threshold(struct zone *zone)
 111 {
 112         int threshold;
 113         int mem;        /* memory in 128 MB units */
 114
 115         /*
 116          * The threshold scales with the number of processors and the amount
 117          * of memory per zone. More memory means that we can defer updates for
 118          * longer, more processors could lead to more contention.
 119          * fls() is used to have a cheap way of logarithmic scaling.
 120          *
 121          * Some sample thresholds:
 122          *
 123          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
 124          * ------------------------------------------------------------------
 125          * 8            1               1       0.9-1 GB        4
 126          * 16           2               2       0.9-1 GB        4
 127          * 20           2               2       1-2 GB          5
 128          * 24           2               2       2-4 GB          6
 129          * 28           2               2       4-8 GB          7
 130          * 32           2               2       8-16 GB         8
 131          * 4            2               2       <128M           1
 132          * 30           4               3       2-4 GB          5
 133          * 48           4               3       8-16 GB         8
 134          * 32           8               4       1-2 GB          4
 135          * 32           8               4       0.9-1GB         4
 136          * 10           16              5       <128M           1
 137          * 40           16              5       900M            4
 138          * 70           64              7       2-4 GB          5
 139          * 84           64              7       4-8 GB          6
 140          * 108          512             9       4-8 GB          6
 141          * 125          1024            10      8-16 GB         8
 142          * 125          1024            10      16-32 GB        9
 143          */
 144
 145         mem = zone->present_pages >> (27 - PAGE_SHIFT);
 146
 147         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 148
 149         /*
 150          * Maximum threshold is 125
 151          */
 152         threshold = min(125, threshold);
 153
 154         return threshold;
 155 }
 156
 157 /*
 158  * Refresh the thresholds for each zone.
 159  */
 160 void refresh_zone_stat_thresholds(void)
 161 {
 162         struct zone *zone;
 163         int cpu;
 164         int threshold;
 165
 166         for_each_populated_zone(zone) {
 167                 unsigned long max_drift, tolerate_drift;
 168
 169                 threshold = calculate_normal_threshold(zone);
 170
 171                 for_each_online_cpu(cpu)
 172                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 173                                                         = threshold;
 174
 175                 /*
 176                  * Only set percpu_drift_mark if there is a danger that
 177                  * NR_FREE_PAGES reports the low watermark is ok when in fact
 178                  * the min watermark could be breached by an allocation
 179                  */
 180                 tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
 181                 max_drift = num_online_cpus() * threshold;
 182                 if (max_drift > tolerate_drift)
 183                         zone->percpu_drift_mark = high_wmark_pages(zone) +
 184                                         max_drift;
 185         }
 186 }
 187
 188 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
 189                                 int (*calculate_pressure)(struct zone *))
 190 {
 191         struct zone *zone;
 192         int cpu;
 193         int threshold;
 194         int i;
 195
 196         for (i = 0; i < pgdat->nr_zones; i++) {
 197                 zone = &pgdat->node_zones[i];
 198                 if (!zone->percpu_drift_mark)
 199                         continue;
 200
 201                 threshold = (*calculate_pressure)(zone);
 202                 for_each_possible_cpu(cpu)
 203                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 204                                                         = threshold;
 205         }
 206 }
 207
 208 /*
 209  * For use when we know that interrupts are disabled.
 210  */
 211 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 212                                 int delta)
 213 {
 214         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 215         s8 __percpu *p = pcp->vm_stat_diff + item;
 216         long x;
 217         long t;
 218
 219         x = delta + __this_cpu_read(*p);
 220
 221         t = __this_cpu_read(pcp->stat_threshold);
 222
 223         if (unlikely(x > t || x < -t)) {
 224                 zone_page_state_add(x, zone, item);
 225                 x = 0;
 226         }
 227         __this_cpu_write(*p, x);
 228 }
 229 EXPORT_SYMBOL(__mod_zone_page_state);
 230
 231 /*
 232  * Optimized increment and decrement functions.
 233  *
 234  * These are only for a single page and therefore can take a struct page *
 235  * argument instead of struct zone *. This allows the inclusion of the code
 236  * generated for page_zone(page) into the optimized functions.
 237  *
 238  * No overflow check is necessary and therefore the differential can be
 239  * incremented or decremented in place which may allow the compilers to
 240  * generate better code.
 241  * The increment or decrement is known and therefore one boundary check can
 242  * be omitted.
 243  *
 244  * NOTE: These functions are very performance sensitive. Change only
 245  * with care.
 246  *
 247  * Some processors have inc/dec instructions that are atomic vs an interrupt.
 248  * However, the code must first determine the differential location in a zone
 249  * based on the processor number and then inc/dec the counter. There is no
 250  * guarantee without disabling preemption that the processor will not change
 251  * in between and therefore the atomicity vs. interrupt cannot be exploited
 252  * in a useful way here.
 253  */
 254 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 255 {
 256         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 257         s8 __percpu *p = pcp->vm_stat_diff + item;
 258         s8 v, t;
 259
 260         v = __this_cpu_inc_return(*p);
 261         t = __this_cpu_read(pcp->stat_threshold);
 262         if (unlikely(v > t)) {
 263                 s8 overstep = t >> 1;
 264
 265                 zone_page_state_add(v + overstep, zone, item);
 266                 __this_cpu_write(*p, -overstep);
 267         }
 268 }
 269
 270 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 271 {
 272         __inc_zone_state(page_zone(page), item);
 273 }
 274 EXPORT_SYMBOL(__inc_zone_page_state);
 275
 276 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 277 {
 278         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 279         s8 __percpu *p = pcp->vm_stat_diff + item;
 280         s8 v, t;
 281
 282         v = __this_cpu_dec_return(*p);
 283         t = __this_cpu_read(pcp->stat_threshold);
 284         if (unlikely(v < - t)) {
 285                 s8 overstep = t >> 1;
 286
 287                 zone_page_state_add(v - overstep, zone, item);
 288                 __this_cpu_write(*p, overstep);
 289         }
 290 }
 291
 292 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 293 {
 294         __dec_zone_state(page_zone(page), item);
 295 }
 296 EXPORT_SYMBOL(__dec_zone_page_state);
 297
 298 #ifdef CONFIG_CMPXCHG_LOCAL
 299 /*
 300  * If we have cmpxchg_local support then we do not need to incur the overhead
 301  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
 302  *
 303  * mod_state() modifies the zone counter state through atomic per cpu
 304  * operations.
 305  *
 306  * Overstep mode specifies how overstep should handled:
 307  *     0       No overstepping
 308  *     1       Overstepping half of threshold
 309  *     -1      Overstepping minus half of threshold
 310 */
 311 static inline void mod_state(struct zone *zone,
 312        enum zone_stat_item item, int delta, int overstep_mode)
 313 {
 314         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 315         s8 __percpu *p = pcp->vm_stat_diff + item;
 316         long o, n, t, z;
 317
 318         do {
 319                 z = 0;  /* overflow to zone counters */
 320
 321                 /*
 322                  * The fetching of the stat_threshold is racy. We may apply
 323                  * a counter threshold to the wrong the cpu if we get
 324                  * rescheduled while executing here. However, the next
 325                  * counter update will apply the threshold again and
 326                  * therefore bring the counter under the threshold again.
 327                  *
 328                  * Most of the time the thresholds are the same anyways
 329                  * for all cpus in a zone.
 330                  */
 331                 t = this_cpu_read(pcp->stat_threshold);
 332
 333                 o = this_cpu_read(*p);
 334                 n = delta + o;
 335
 336                 if (n > t || n < -t) {
 337                         int os = overstep_mode * (t >> 1) ;
 338
 339                         /* Overflow must be added to zone counters */
 340                         z = n + os;
 341                         n = -os;
 342                 }
 343         } while (this_cpu_cmpxchg(*p, o, n) != o);
 344
 345         if (z)
 346                 zone_page_state_add(z, zone, item);
 347 }
 348
 349 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 350                                         int delta)
 351 {
 352         mod_state(zone, item, delta, 0);
 353 }
 354 EXPORT_SYMBOL(mod_zone_page_state);
 355
 356 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 357 {
 358         mod_state(zone, item, 1, 1);
 359 }
 360
 361 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 362 {
 363         mod_state(page_zone(page), item, 1, 1);
 364 }
 365 EXPORT_SYMBOL(inc_zone_page_state);
 366
 367 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 368 {
 369         mod_state(page_zone(page), item, -1, -1);
 370 }
 371 EXPORT_SYMBOL(dec_zone_page_state);
 372 #else
 373 /*
 374  * Use interrupt disable to serialize counter updates
 375  */
 376 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 377                                         int delta)
 378 {
 379         unsigned long flags;
 380
 381         local_irq_save(flags);
 382         __mod_zone_page_state(zone, item, delta);
 383         local_irq_restore(flags);
 384 }
 385 EXPORT_SYMBOL(mod_zone_page_state);
 386
 387 void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 388 {
 389         unsigned long flags;
 390
 391         local_irq_save(flags);
 392         __inc_zone_state(zone, item);
 393         local_irq_restore(flags);
 394 }
 395
 396 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 397 {
 398         unsigned long flags;
 399         struct zone *zone;
 400
 401         zone = page_zone(page);
 402         local_irq_save(flags);
 403         __inc_zone_state(zone, item);
 404         local_irq_restore(flags);
 405 }
 406 EXPORT_SYMBOL(inc_zone_page_state);
 407
 408 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 409 {
 410         unsigned long flags;
 411
 412         local_irq_save(flags);
 413         __dec_zone_page_state(page, item);
 414         local_irq_restore(flags);
 415 }
 416 EXPORT_SYMBOL(dec_zone_page_state);
 417 #endif
 418
 419 /*
 420  * Update the zone counters for one cpu.
 421  *
 422  * The cpu specified must be either the current cpu or a processor that
 423  * is not online. If it is the current cpu then the execution thread must
 424  * be pinned to the current cpu.
 425  *
 426  * Note that refresh_cpu_vm_stats strives to only access
 427  * node local memory. The per cpu pagesets on remote zones are placed
 428  * in the memory local to the processor using that pageset. So the
 429  * loop over all zones will access a series of cachelines local to
 430  * the processor.
 431  *
 432  * The call to zone_page_state_add updates the cachelines with the
 433  * statistics in the remote zone struct as well as the global cachelines
 434  * with the global counters. These could cause remote node cache line
 435  * bouncing and will have to be only done when necessary.
 436  */
 437 void refresh_cpu_vm_stats(int cpu)
 438 {
 439         struct zone *zone;
 440         int i;
 441         int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 442
 443         for_each_populated_zone(zone) {
 444                 struct per_cpu_pageset *p;
 445
 446                 p = per_cpu_ptr(zone->pageset, cpu);
 447
 448                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 449                         if (p->vm_stat_diff[i]) {
 450                                 unsigned long flags;
 451                                 int v;
 452
 453                                 local_irq_save(flags);
 454                                 v = p->vm_stat_diff[i];
 455                                 p->vm_stat_diff[i] = 0;
 456                                 local_irq_restore(flags);
 457                                 atomic_long_add(v, &zone->vm_stat[i]);
 458                                 global_diff[i] += v;
 459 #ifdef CONFIG_NUMA
 460                                 /* 3 seconds idle till flush */
 461                                 p->expire = 3;
 462 #endif
 463                         }
 464                 cond_resched();
 465 #ifdef CONFIG_NUMA
 466                 /*
 467                  * Deal with draining the remote pageset of this
 468                  * processor
 469                  *
 470                  * Check if there are pages remaining in this pageset
 471                  * if not then there is nothing to expire.
 472                  */
 473                 if (!p->expire || !p->pcp.count)
 474                         continue;
 475
 476                 /*
 477                  * We never drain zones local to this processor.
 478                  */
 479                 if (zone_to_nid(zone) == numa_node_id()) {
 480                         p->expire = 0;
 481                         continue;
 482                 }
 483
 484                 p->expire--;
 485                 if (p->expire)
 486                         continue;
 487
 488                 if (p->pcp.count)
 489                         drain_zone_pages(zone, &p->pcp);
 490 #endif
 491         }
 492
 493         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 494                 if (global_diff[i])
 495                         atomic_long_add(global_diff[i], &vm_stat[i]);
 496 }
 497
 498 #endif
 499
 500 #ifdef CONFIG_NUMA
 501 /*
 502  * zonelist = the list of zones passed to the allocator
 503  * z        = the zone from which the allocation occurred.
 504  *
 505  * Must be called with interrupts disabled.
 506  *
 507  * When __GFP_OTHER_NODE is set assume the node of the preferred
 508  * zone is the local node. This is useful for daemons who allocate
 509  * memory on behalf of other processes.
 510  */
 511 void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 512 {
 513         if (z->zone_pgdat == preferred_zone->zone_pgdat) {
 514                 __inc_zone_state(z, NUMA_HIT);
 515         } else {
 516                 __inc_zone_state(z, NUMA_MISS);
 517                 __inc_zone_state(preferred_zone, NUMA_FOREIGN);
 518         }
 519         if (z->node == ((flags & __GFP_OTHER_NODE) ?
 520                         preferred_zone->node : numa_node_id()))
 521                 __inc_zone_state(z, NUMA_LOCAL);
 522         else
 523                 __inc_zone_state(z, NUMA_OTHER);
 524 }
 525 #endif
 526
 527 #ifdef CONFIG_COMPACTION
 528
 529 struct contig_page_info {
 530         unsigned long free_pages;
 531         unsigned long free_blocks_total;
 532         unsigned long free_blocks_suitable;
 533 };
 534
 535 /*
 536  * Calculate the number of free pages in a zone, how many contiguous
 537  * pages are free and how many are large enough to satisfy an allocation of
 538  * the target size. Note that this function makes no attempt to estimate
 539  * how many suitable free blocks there *might* be if MOVABLE pages were
 540  * migrated. Calculating that is possible, but expensive and can be
 541  * figured out from userspace
 542  */
 543 static void fill_contig_page_info(struct zone *zone,
 544                                 unsigned int suitable_order,
 545                                 struct contig_page_info *info)
 546 {
 547         unsigned int order;
 548
 549         info->free_pages = 0;
 550         info->free_blocks_total = 0;
 551         info->free_blocks_suitable = 0;
 552
 553         for (order = 0; order < MAX_ORDER; order++) {
 554                 unsigned long blocks;
 555
 556                 /* Count number of free blocks */
 557                 blocks = zone->free_area[order].nr_free;
 558                 info->free_blocks_total += blocks;
 559
 560                 /* Count free base pages */
 561                 info->free_pages += blocks << order;
 562
 563                 /* Count the suitable free blocks */
 564                 if (order >= suitable_order)
 565                         info->free_blocks_suitable += blocks <<
 566                                                 (order - suitable_order);
 567         }
 568 }
 569
 570 /*
 571  * A fragmentation index only makes sense if an allocation of a requested
 572  * size would fail. If that is true, the fragmentation index indicates
 573  * whether external fragmentation or a lack of memory was the problem.
 574  * The value can be used to determine if page reclaim or compaction
 575  * should be used
 576  */
 577 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
 578 {
 579         unsigned long requested = 1UL << order;
 580
 581         if (!info->free_blocks_total)
 582                 return 0;
 583
 584         /* Fragmentation index only makes sense when a request would fail */
 585         if (info->free_blocks_suitable)
 586                 return -1000;
 587
 588         /*
 589          * Index is between 0 and 1 so return within 3 decimal places
 590          *
 591          * 0 => allocation would fail due to lack of memory
 592          * 1 => allocation would fail due to fragmentation
 593          */
 594         return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
 595 }
 596
 597 /* Same as __fragmentation index but allocs contig_page_info on stack */
 598 int fragmentation_index(struct zone *zone, unsigned int order)
 599 {
 600         struct contig_page_info info;
 601
 602         fill_contig_page_info(zone, order, &info);
 603         return __fragmentation_index(order, &info);
 604 }
 605 #endif
 606
 607 #if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
 608 #include <linux/proc_fs.h>
 609 #include <linux/seq_file.h>
 610
 611 static char * const migratetype_names[MIGRATE_TYPES] = {
 612         "Unmovable",
 613         "Reclaimable",
 614         "Movable",
 615         "Reserve",
 616 #ifdef CONFIG_CMA
 617         "CMA",
 618 #endif
 619         "Isolate",
 620 };
 621
 622 static void *frag_start(struct seq_file *m, loff_t *pos)
 623 {
 624         pg_data_t *pgdat;
 625         loff_t node = *pos;
 626         for (pgdat = first_online_pgdat();
 627              pgdat && node;
 628              pgdat = next_online_pgdat(pgdat))
 629                 --node;
 630
 631         return pgdat;
 632 }
 633
 634 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 635 {
 636         pg_data_t *pgdat = (pg_data_t *)arg;
 637
 638         (*pos)++;
 639         return next_online_pgdat(pgdat);
 640 }
 641
 642 static void frag_stop(struct seq_file *m, void *arg)
 643 {
 644 }
 645
 646 /* Walk all the zones in a node and print using a callback */
 647 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 648                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 649 {
 650         struct zone *zone;
 651         struct zone *node_zones = pgdat->node_zones;
 652         unsigned long flags;
 653
 654         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 655                 if (!populated_zone(zone))
 656                         continue;
 657
 658                 spin_lock_irqsave(&zone->lock, flags);
 659                 print(m, pgdat, zone);
 660                 spin_unlock_irqrestore(&zone->lock, flags);
 661         }
 662 }
 663 #endif
 664
 665 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 666 #ifdef CONFIG_ZONE_DMA
 667 #define TEXT_FOR_DMA(xx) xx "_dma",
 668 #else
 669 #define TEXT_FOR_DMA(xx)
 670 #endif
 671
 672 #ifdef CONFIG_ZONE_DMA32
 673 #define TEXT_FOR_DMA32(xx) xx "_dma32",
 674 #else
 675 #define TEXT_FOR_DMA32(xx)
 676 #endif
 677
 678 #ifdef CONFIG_HIGHMEM
 679 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
 680 #else
 681 #define TEXT_FOR_HIGHMEM(xx)
 682 #endif
 683
 684 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 685                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
 686
 687 const char * const vmstat_text[] = {
 688         /* Zoned VM counters */
 689         "nr_free_pages",
 690         "nr_inactive_anon",
 691         "nr_active_anon",
 692         "nr_inactive_file",
 693         "nr_active_file",
 694         "nr_unevictable",
 695         "nr_mlock",
 696         "nr_anon_pages",
 697         "nr_mapped",
 698         "nr_file_pages",
 699         "nr_dirty",
 700         "nr_writeback",
 701         "nr_slab_reclaimable",
 702         "nr_slab_unreclaimable",
 703         "nr_page_table_pages",
 704         "nr_kernel_stack",
 705         "nr_unstable",
 706         "nr_bounce",
 707         "nr_vmscan_write",
 708         "nr_vmscan_immediate_reclaim",
 709         "nr_writeback_temp",
 710         "nr_isolated_anon",
 711         "nr_isolated_file",
 712         "nr_shmem",
 713         "nr_dirtied",
 714         "nr_written",
 715
 716 #ifdef CONFIG_NUMA
 717         "numa_hit",
 718         "numa_miss",
 719         "numa_foreign",
 720         "numa_interleave",
 721         "numa_local",
 722         "numa_other",
 723 #endif
 724         "nr_anon_transparent_hugepages",
 725         "nr_dirty_threshold",
 726         "nr_dirty_background_threshold",
 727
 728 #ifdef CONFIG_VM_EVENT_COUNTERS
 729         "pgpgin",
 730         "pgpgout",
 731         "pswpin",
 732         "pswpout",
 733
 734         TEXTS_FOR_ZONES("pgalloc")
 735
 736         "pgfree",
 737         "pgactivate",
 738         "pgdeactivate",
 739
 740         "pgfault",
 741         "pgmajfault",
 742
 743         TEXTS_FOR_ZONES("pgrefill")
 744         TEXTS_FOR_ZONES("pgsteal")
 745         TEXTS_FOR_ZONES("pgscan_kswapd")
 746         TEXTS_FOR_ZONES("pgscan_direct")
 747
 748 #ifdef CONFIG_NUMA
 749         "zone_reclaim_failed",
 750 #endif
 751         "pginodesteal",
 752         "slabs_scanned",
 753         "kswapd_steal",
 754         "kswapd_inodesteal",
 755         "kswapd_low_wmark_hit_quickly",
 756         "kswapd_high_wmark_hit_quickly",
 757         "kswapd_skip_congestion_wait",
 758         "pageoutrun",
 759         "allocstall",
 760
 761         "pgrotated",
 762
 763 #ifdef CONFIG_COMPACTION
 764         "compact_blocks_moved",
 765         "compact_pages_moved",
 766         "compact_pagemigrate_failed",
 767         "compact_stall",
 768         "compact_fail",
 769         "compact_success",
 770 #endif
 771
 772 #ifdef CONFIG_HUGETLB_PAGE
 773         "htlb_buddy_alloc_success",
 774         "htlb_buddy_alloc_fail",
 775 #endif
 776         "unevictable_pgs_culled",
 777         "unevictable_pgs_scanned",
 778         "unevictable_pgs_rescued",
 779         "unevictable_pgs_mlocked",
 780         "unevictable_pgs_munlocked",
 781         "unevictable_pgs_cleared",
 782         "unevictable_pgs_stranded",
 783         "unevictable_pgs_mlockfreed",
 784
 785 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 786         "thp_fault_alloc",
 787         "thp_fault_fallback",
 788         "thp_collapse_alloc",
 789         "thp_collapse_alloc_failed",
 790         "thp_split",
 791 #endif
 792
 793 #endif /* CONFIG_VM_EVENTS_COUNTERS */
 794 };
 795 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 796
 797
 798 #ifdef CONFIG_PROC_FS
 799 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 800                                                 struct zone *zone)
 801 {
 802         int order;
 803
 804         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 805         for (order = 0; order < MAX_ORDER; ++order)
 806                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 807         seq_putc(m, '\n');
 808 }
 809
 810 /*
 811  * This walks the free areas for each zone.
 812  */
 813 static int frag_show(struct seq_file *m, void *arg)
 814 {
 815         pg_data_t *pgdat = (pg_data_t *)arg;
 816         walk_zones_in_node(m, pgdat, frag_show_print);
 817         return 0;
 818 }
 819
 820 static void pagetypeinfo_showfree_print(struct seq_file *m,
 821                                         pg_data_t *pgdat, struct zone *zone)
 822 {
 823         int order, mtype;
 824
 825         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 826                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
 827                                         pgdat->node_id,
 828                                         zone->name,
 829                                         migratetype_names[mtype]);
 830                 for (order = 0; order < MAX_ORDER; ++order) {
 831                         unsigned long freecount = 0;
 832                         struct free_area *area;
 833                         struct list_head *curr;
 834
 835                         area = &(zone->free_area[order]);
 836
 837                         list_for_each(curr, &area->free_list[mtype])
 838                                 freecount++;
 839                         seq_printf(m, "%6lu ", freecount);
 840                 }
 841                 seq_putc(m, '\n');
 842         }
 843 }
 844
 845 /* Print out the free pages at each order for each migatetype */
 846 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 847 {
 848         int order;
 849         pg_data_t *pgdat = (pg_data_t *)arg;
 850
 851         /* Print header */
 852         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 853         for (order = 0; order < MAX_ORDER; ++order)
 854                 seq_printf(m, "%6d ", order);
 855         seq_putc(m, '\n');
 856
 857         walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 858
 859         return 0;
 860 }
 861
 862 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 863                                         pg_data_t *pgdat, struct zone *zone)
 864 {
 865         int mtype;
 866         unsigned long pfn;
 867         unsigned long start_pfn = zone->zone_start_pfn;
 868         unsigned long end_pfn = start_pfn + zone->spanned_pages;
 869         unsigned long count[MIGRATE_TYPES] = { 0, };
 870
 871         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 872                 struct page *page;
 873
 874                 if (!pfn_valid(pfn))
 875                         continue;
 876
 877                 page = pfn_to_page(pfn);
 878
 879                 /* Watch for unexpected holes punched in the memmap */
 880                 if (!memmap_valid_within(pfn, page, zone))
 881                         continue;
 882
 883                 mtype = get_pageblock_migratetype(page);
 884
 885                 if (mtype < MIGRATE_TYPES)
 886                         count[mtype]++;
 887         }
 888
 889         /* Print counts */
 890         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 891         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 892                 seq_printf(m, "%12lu ", count[mtype]);
 893         seq_putc(m, '\n');
 894 }
 895
 896 /* Print out the free pages at each order for each migratetype */
 897 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 898 {
 899         int mtype;
 900         pg_data_t *pgdat = (pg_data_t *)arg;
 901
 902         seq_printf(m, "\n%-23s", "Number of blocks type ");
 903         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 904                 seq_printf(m, "%12s ", migratetype_names[mtype]);
 905         seq_putc(m, '\n');
 906         walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 907
 908         return 0;
 909 }
 910
 911 /*
 912  * This prints out statistics in relation to grouping pages by mobility.
 913  * It is expensive to collect so do not constantly read the file.
 914  */
 915 static int pagetypeinfo_show(struct seq_file *m, void *arg)
 916 {
 917         pg_data_t *pgdat = (pg_data_t *)arg;
 918
 919         /* check memoryless node */
 920         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
 921                 return 0;
 922
 923         seq_printf(m, "Page block order: %d\n", pageblock_order);
 924         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 925         seq_putc(m, '\n');
 926         pagetypeinfo_showfree(m, pgdat);
 927         pagetypeinfo_showblockcount(m, pgdat);
 928
 929         return 0;
 930 }
 931
 932 static const struct seq_operations fragmentation_op = {
 933         .start  = frag_start,
 934         .next   = frag_next,
 935         .stop   = frag_stop,
 936         .show   = frag_show,
 937 };
 938
 939 static int fragmentation_open(struct inode *inode, struct file *file)
 940 {
 941         return seq_open(file, &fragmentation_op);
 942 }
 943
 944 static const struct file_operations fragmentation_file_operations = {
 945         .open           = fragmentation_open,
 946         .read           = seq_read,
 947         .llseek         = seq_lseek,
 948         .release        = seq_release,
 949 };
 950
 951 static const struct seq_operations pagetypeinfo_op = {
 952         .start  = frag_start,
 953         .next   = frag_next,
 954         .stop   = frag_stop,
 955         .show   = pagetypeinfo_show,
 956 };
 957
 958 static int pagetypeinfo_open(struct inode *inode, struct file *file)
 959 {
 960         return seq_open(file, &pagetypeinfo_op);
 961 }
 962
 963 static const struct file_operations pagetypeinfo_file_ops = {
 964         .open           = pagetypeinfo_open,
 965         .read           = seq_read,
 966         .llseek         = seq_lseek,
 967         .release        = seq_release,
 968 };
 969
 970 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 971                                                         struct zone *zone)
 972 {
 973         int i;
 974         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
 975         seq_printf(m,
 976                    "\n  pages free     %lu"
 977                    "\n        min      %lu"
 978                    "\n        low      %lu"
 979                    "\n        high     %lu"
 980                    "\n        scanned  %lu"
 981                    "\n        spanned  %lu"
 982                    "\n        present  %lu",
 983                    zone_page_state(zone, NR_FREE_PAGES),
 984                    min_wmark_pages(zone),
 985                    low_wmark_pages(zone),
 986                    high_wmark_pages(zone),
 987                    zone->pages_scanned,
 988                    zone->spanned_pages,
 989                    zone->present_pages);
 990
 991         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 992                 seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
 993                                 zone_page_state(zone, i));
 994
 995         seq_printf(m,
 996                    "\n        protection: (%lu",
 997                    zone->lowmem_reserve[0]);
 998         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
 999                 seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
1000         seq_printf(m,
1001                    ")"
1002                    "\n  pagesets");
1003         for_each_online_cpu(i) {
1004                 struct per_cpu_pageset *pageset;
1005
1006                 pageset = per_cpu_ptr(zone->pageset, i);
1007                 seq_printf(m,
1008                            "\n    cpu: %i"
1009                            "\n              count: %i"
1010                            "\n              high:  %i"
1011                            "\n              batch: %i",
1012                            i,
1013                            pageset->pcp.count,
1014                            pageset->pcp.high,
1015                            pageset->pcp.batch);
1016 #ifdef CONFIG_SMP
1017                 seq_printf(m, "\n  vm stats threshold: %d",
1018                                 pageset->stat_threshold);
1019 #endif
1020         }
1021         seq_printf(m,
1022                    "\n  all_unreclaimable: %u"
1023                    "\n  start_pfn:         %lu"
1024                    "\n  inactive_ratio:    %u",
1025                    zone->all_unreclaimable,
1026                    zone->zone_start_pfn,
1027                    zone->inactive_ratio);
1028         seq_putc(m, '\n');
1029 }
1030
1031 /*
1032  * Output information about zones in @pgdat.
1033  */
1034 static int zoneinfo_show(struct seq_file *m, void *arg)
1035 {
1036         pg_data_t *pgdat = (pg_data_t *)arg;
1037         walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1038         return 0;
1039 }
1040
1041 static const struct seq_operations zoneinfo_op = {
1042         .start  = frag_start, /* iterate over all zones. The same as in
1043                                * fragmentation. */
1044         .next   = frag_next,
1045         .stop   = frag_stop,
1046         .show   = zoneinfo_show,
1047 };
1048
1049 static int zoneinfo_open(struct inode *inode, struct file *file)
1050 {
1051         return seq_open(file, &zoneinfo_op);
1052 }
1053
1054 static const struct file_operations proc_zoneinfo_file_operations = {
1055         .open           = zoneinfo_open,
1056         .read           = seq_read,
1057         .llseek         = seq_lseek,
1058         .release        = seq_release,
1059 };
1060
1061 enum writeback_stat_item {
1062         NR_DIRTY_THRESHOLD,
1063         NR_DIRTY_BG_THRESHOLD,
1064         NR_VM_WRITEBACK_STAT_ITEMS,
1065 };
1066
1067 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1068 {
1069         unsigned long *v;
1070         int i, stat_items_size;
1071
1072         if (*pos >= ARRAY_SIZE(vmstat_text))
1073                 return NULL;
1074         stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1075                           NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1076
1077 #ifdef CONFIG_VM_EVENT_COUNTERS
1078         stat_items_size += sizeof(struct vm_event_state);
1079 #endif
1080
1081         v = kmalloc(stat_items_size, GFP_KERNEL);
1082         m->private = v;
1083         if (!v)
1084                 return ERR_PTR(-ENOMEM);
1085         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1086                 v[i] = global_page_state(i);
1087         v += NR_VM_ZONE_STAT_ITEMS;
1088
1089         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1090                             v + NR_DIRTY_THRESHOLD);
1091         v += NR_VM_WRITEBACK_STAT_ITEMS;
1092
1093 #ifdef CONFIG_VM_EVENT_COUNTERS
1094         all_vm_events(v);
1095         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1096         v[PGPGOUT] /= 2;
1097 #endif
1098         return (unsigned long *)m->private + *pos;
1099 }
1100
1101 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1102 {
1103         (*pos)++;
1104         if (*pos >= ARRAY_SIZE(vmstat_text))
1105                 return NULL;
1106         return (unsigned long *)m->private + *pos;
1107 }
1108
1109 static int vmstat_show(struct seq_file *m, void *arg)
1110 {
1111         unsigned long *l = arg;
1112         unsigned long off = l - (unsigned long *)m->private;
1113
1114         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1115         return 0;
1116 }
1117
1118 static void vmstat_stop(struct seq_file *m, void *arg)
1119 {
1120         kfree(m->private);
1121         m->private = NULL;
1122 }
1123
1124 static const struct seq_operations vmstat_op = {
1125         .start  = vmstat_start,
1126         .next   = vmstat_next,
1127         .stop   = vmstat_stop,
1128         .show   = vmstat_show,
1129 };
1130
1131 static int vmstat_open(struct inode *inode, struct file *file)
1132 {
1133         return seq_open(file, &vmstat_op);
1134 }
1135
1136 static const struct file_operations proc_vmstat_file_operations = {
1137         .open           = vmstat_open,
1138         .read           = seq_read,
1139         .llseek         = seq_lseek,
1140         .release        = seq_release,
1141 };
1142 #endif /* CONFIG_PROC_FS */
1143
1144 #ifdef CONFIG_SMP
1145 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1146 int sysctl_stat_interval __read_mostly = HZ;
1147
1148 static void vmstat_update(struct work_struct *w)
1149 {
1150         refresh_cpu_vm_stats(smp_processor_id());
1151         schedule_delayed_work(&__get_cpu_var(vmstat_work),
1152                 round_jiffies_relative(sysctl_stat_interval));
1153 }
1154
1155 static void __cpuinit start_cpu_timer(int cpu)
1156 {
1157         struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1158
1159         INIT_DELAYED_WORK_DEFERRABLE(work, vmstat_update);
1160         schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1161 }
1162
1163 /*
1164  * Use the cpu notifier to insure that the thresholds are recalculated
1165  * when necessary.
1166  */
1167 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1168                 unsigned long action,
1169                 void *hcpu)
1170 {
1171         long cpu = (long)hcpu;
1172
1173         switch (action) {
1174         case CPU_ONLINE:
1175         case CPU_ONLINE_FROZEN:
1176                 refresh_zone_stat_thresholds();
1177                 start_cpu_timer(cpu);
1178                 node_set_state(cpu_to_node(cpu), N_CPU);
1179                 break;
1180         case CPU_DOWN_PREPARE:
1181         case CPU_DOWN_PREPARE_FROZEN:
1182                 cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1183                 per_cpu(vmstat_work, cpu).work.func = NULL;
1184                 break;
1185         case CPU_DOWN_FAILED:
1186         case CPU_DOWN_FAILED_FROZEN:
1187                 start_cpu_timer(cpu);
1188                 break;
1189         case CPU_DEAD:
1190         case CPU_DEAD_FROZEN:
1191                 refresh_zone_stat_thresholds();
1192                 break;
1193         default:
1194                 break;
1195         }
1196         return NOTIFY_OK;
1197 }
1198
1199 static struct notifier_block __cpuinitdata vmstat_notifier =
1200         { &vmstat_cpuup_callback, NULL, 0 };
1201 #endif
1202
1203 static int __init setup_vmstat(void)
1204 {
1205 #ifdef CONFIG_SMP
1206         int cpu;
1207
1208         register_cpu_notifier(&vmstat_notifier);
1209
1210         for_each_online_cpu(cpu)
1211                 start_cpu_timer(cpu);
1212 #endif
1213 #ifdef CONFIG_PROC_FS
1214         proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1215         proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1216         proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1217         proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1218 #endif
1219         return 0;
1220 }
1221 module_init(setup_vmstat)
1222
1223 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1224 #include <linux/debugfs.h>
1225
1226 static struct dentry *extfrag_debug_root;
1227
1228 /*
1229  * Return an index indicating how much of the available free memory is
1230  * unusable for an allocation of the requested size.
1231  */
1232 static int unusable_free_index(unsigned int order,
1233                                 struct contig_page_info *info)
1234 {
1235         /* No free memory is interpreted as all free memory is unusable */
1236         if (info->free_pages == 0)
1237                 return 1000;
1238
1239         /*
1240          * Index should be a value between 0 and 1. Return a value to 3
1241          * decimal places.
1242          *
1243          * 0 => no fragmentation
1244          * 1 => high fragmentation
1245          */
1246         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1247
1248 }
1249
1250 static void unusable_show_print(struct seq_file *m,
1251                                         pg_data_t *pgdat, struct zone *zone)
1252 {
1253         unsigned int order;
1254         int index;
1255         struct contig_page_info info;
1256
1257         seq_printf(m, "Node %d, zone %8s ",
1258                                 pgdat->node_id,
1259                                 zone->name);
1260         for (order = 0; order < MAX_ORDER; ++order) {
1261                 fill_contig_page_info(zone, order, &info);
1262                 index = unusable_free_index(order, &info);
1263                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1264         }
1265
1266         seq_putc(m, '\n');
1267 }
1268
1269 /*
1270  * Display unusable free space index
1271  *
1272  * The unusable free space index measures how much of the available free
1273  * memory cannot be used to satisfy an allocation of a given size and is a
1274  * value between 0 and 1. The higher the value, the more of free memory is
1275  * unusable and by implication, the worse the external fragmentation is. This
1276  * can be expressed as a percentage by multiplying by 100.
1277  */
1278 static int unusable_show(struct seq_file *m, void *arg)
1279 {
1280         pg_data_t *pgdat = (pg_data_t *)arg;
1281
1282         /* check memoryless node */
1283         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
1284                 return 0;
1285
1286         walk_zones_in_node(m, pgdat, unusable_show_print);
1287
1288         return 0;
1289 }
1290
1291 static const struct seq_operations unusable_op = {
1292         .start  = frag_start,
1293         .next   = frag_next,
1294         .stop   = frag_stop,
1295         .show   = unusable_show,
1296 };
1297
1298 static int unusable_open(struct inode *inode, struct file *file)
1299 {
1300         return seq_open(file, &unusable_op);
1301 }
1302
1303 static const struct file_operations unusable_file_ops = {
1304         .open           = unusable_open,
1305         .read           = seq_read,
1306         .llseek         = seq_lseek,
1307         .release        = seq_release,
1308 };
1309
1310 static void extfrag_show_print(struct seq_file *m,
1311                                         pg_data_t *pgdat, struct zone *zone)
1312 {
1313         unsigned int order;
1314         int index;
1315
1316         /* Alloc on stack as interrupts are disabled for zone walk */
1317         struct contig_page_info info;
1318
1319         seq_printf(m, "Node %d, zone %8s ",
1320                                 pgdat->node_id,
1321                                 zone->name);
1322         for (order = 0; order < MAX_ORDER; ++order) {
1323                 fill_contig_page_info(zone, order, &info);
1324                 index = __fragmentation_index(order, &info);
1325                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1326         }
1327
1328         seq_putc(m, '\n');
1329 }
1330
1331 /*
1332  * Display fragmentation index for orders that allocations would fail for
1333  */
1334 static int extfrag_show(struct seq_file *m, void *arg)
1335 {
1336         pg_data_t *pgdat = (pg_data_t *)arg;
1337
1338         walk_zones_in_node(m, pgdat, extfrag_show_print);
1339
1340         return 0;
1341 }
1342
1343 static const struct seq_operations extfrag_op = {
1344         .start  = frag_start,
1345         .next   = frag_next,
1346         .stop   = frag_stop,
1347         .show   = extfrag_show,
1348 };
1349
1350 static int extfrag_open(struct inode *inode, struct file *file)
1351 {
1352         return seq_open(file, &extfrag_op);
1353 }
1354
1355 static const struct file_operations extfrag_file_ops = {
1356         .open           = extfrag_open,
1357         .read           = seq_read,
1358         .llseek         = seq_lseek,
1359         .release        = seq_release,
1360 };
1361
1362 static int __init extfrag_debug_init(void)
1363 {
1364         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1365         if (!extfrag_debug_root)
1366                 return -ENOMEM;
1367
1368         if (!debugfs_create_file("unusable_index", 0444,
1369                         extfrag_debug_root, NULL, &unusable_file_ops))
1370                 return -ENOMEM;
1371
1372         if (!debugfs_create_file("extfrag_index", 0444,
1373                         extfrag_debug_root, NULL, &extfrag_file_ops))
1374                 return -ENOMEM;
1375
1376         return 0;
1377 }
1378
1379 module_init(extfrag_debug_init);
1380 #endif