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_HAVE_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         "Isolate",
 617 };
 618
 619 static void *frag_start(struct seq_file *m, loff_t *pos)
 620 {
 621         pg_data_t *pgdat;
 622         loff_t node = *pos;
 623         for (pgdat = first_online_pgdat();
 624              pgdat && node;
 625              pgdat = next_online_pgdat(pgdat))
 626                 --node;
 627
 628         return pgdat;
 629 }
 630
 631 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 632 {
 633         pg_data_t *pgdat = (pg_data_t *)arg;
 634
 635         (*pos)++;
 636         return next_online_pgdat(pgdat);
 637 }
 638
 639 static void frag_stop(struct seq_file *m, void *arg)
 640 {
 641 }
 642
 643 /* Walk all the zones in a node and print using a callback */
 644 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 645                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 646 {
 647         struct zone *zone;
 648         struct zone *node_zones = pgdat->node_zones;
 649         unsigned long flags;
 650
 651         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 652                 if (!populated_zone(zone))
 653                         continue;
 654
 655                 spin_lock_irqsave(&zone->lock, flags);
 656                 print(m, pgdat, zone);
 657                 spin_unlock_irqrestore(&zone->lock, flags);
 658         }
 659 }
 660 #endif
 661
 662 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 663 #ifdef CONFIG_ZONE_DMA
 664 #define TEXT_FOR_DMA(xx) xx "_dma",
 665 #else
 666 #define TEXT_FOR_DMA(xx)
 667 #endif
 668
 669 #ifdef CONFIG_ZONE_DMA32
 670 #define TEXT_FOR_DMA32(xx) xx "_dma32",
 671 #else
 672 #define TEXT_FOR_DMA32(xx)
 673 #endif
 674
 675 #ifdef CONFIG_HIGHMEM
 676 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
 677 #else
 678 #define TEXT_FOR_HIGHMEM(xx)
 679 #endif
 680
 681 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 682                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
 683
 684 const char * const vmstat_text[] = {
 685         /* Zoned VM counters */
 686         "nr_free_pages",
 687         "nr_inactive_anon",
 688         "nr_active_anon",
 689         "nr_inactive_file",
 690         "nr_active_file",
 691         "nr_unevictable",
 692         "nr_mlock",
 693         "nr_anon_pages",
 694         "nr_mapped",
 695         "nr_file_pages",
 696         "nr_dirty",
 697         "nr_writeback",
 698         "nr_slab_reclaimable",
 699         "nr_slab_unreclaimable",
 700         "nr_page_table_pages",
 701         "nr_kernel_stack",
 702         "nr_unstable",
 703         "nr_bounce",
 704         "nr_vmscan_write",
 705         "nr_vmscan_immediate_reclaim",
 706         "nr_writeback_temp",
 707         "nr_isolated_anon",
 708         "nr_isolated_file",
 709         "nr_shmem",
 710         "nr_dirtied",
 711         "nr_written",
 712
 713 #ifdef CONFIG_NUMA
 714         "numa_hit",
 715         "numa_miss",
 716         "numa_foreign",
 717         "numa_interleave",
 718         "numa_local",
 719         "numa_other",
 720 #endif
 721         "nr_anon_transparent_hugepages",
 722         "nr_dirty_threshold",
 723         "nr_dirty_background_threshold",
 724
 725 #ifdef CONFIG_VM_EVENT_COUNTERS
 726         "pgpgin",
 727         "pgpgout",
 728         "pswpin",
 729         "pswpout",
 730
 731         TEXTS_FOR_ZONES("pgalloc")
 732
 733         "pgfree",
 734         "pgactivate",
 735         "pgdeactivate",
 736
 737         "pgfault",
 738         "pgmajfault",
 739
 740         TEXTS_FOR_ZONES("pgrefill")
 741         TEXTS_FOR_ZONES("pgsteal_kswapd")
 742         TEXTS_FOR_ZONES("pgsteal_direct")
 743         TEXTS_FOR_ZONES("pgscan_kswapd")
 744         TEXTS_FOR_ZONES("pgscan_direct")
 745
 746 #ifdef CONFIG_NUMA
 747         "zone_reclaim_failed",
 748 #endif
 749         "pginodesteal",
 750         "slabs_scanned",
 751         "kswapd_inodesteal",
 752         "kswapd_low_wmark_hit_quickly",
 753         "kswapd_high_wmark_hit_quickly",
 754         "kswapd_skip_congestion_wait",
 755         "pageoutrun",
 756         "allocstall",
 757
 758         "pgrotated",
 759
 760 #ifdef CONFIG_COMPACTION
 761         "compact_blocks_moved",
 762         "compact_pages_moved",
 763         "compact_pagemigrate_failed",
 764         "compact_stall",
 765         "compact_fail",
 766         "compact_success",
 767 #endif
 768
 769 #ifdef CONFIG_HUGETLB_PAGE
 770         "htlb_buddy_alloc_success",
 771         "htlb_buddy_alloc_fail",
 772 #endif
 773         "unevictable_pgs_culled",
 774         "unevictable_pgs_scanned",
 775         "unevictable_pgs_rescued",
 776         "unevictable_pgs_mlocked",
 777         "unevictable_pgs_munlocked",
 778         "unevictable_pgs_cleared",
 779         "unevictable_pgs_stranded",
 780         "unevictable_pgs_mlockfreed",
 781
 782 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 783         "thp_fault_alloc",
 784         "thp_fault_fallback",
 785         "thp_collapse_alloc",
 786         "thp_collapse_alloc_failed",
 787         "thp_split",
 788 #endif
 789
 790 #endif /* CONFIG_VM_EVENTS_COUNTERS */
 791 };
 792 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 793
 794
 795 #ifdef CONFIG_PROC_FS
 796 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 797                                                 struct zone *zone)
 798 {
 799         int order;
 800
 801         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 802         for (order = 0; order < MAX_ORDER; ++order)
 803                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 804         seq_putc(m, '\n');
 805 }
 806
 807 /*
 808  * This walks the free areas for each zone.
 809  */
 810 static int frag_show(struct seq_file *m, void *arg)
 811 {
 812         pg_data_t *pgdat = (pg_data_t *)arg;
 813         walk_zones_in_node(m, pgdat, frag_show_print);
 814         return 0;
 815 }
 816
 817 static void pagetypeinfo_showfree_print(struct seq_file *m,
 818                                         pg_data_t *pgdat, struct zone *zone)
 819 {
 820         int order, mtype;
 821
 822         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 823                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
 824                                         pgdat->node_id,
 825                                         zone->name,
 826                                         migratetype_names[mtype]);
 827                 for (order = 0; order < MAX_ORDER; ++order) {
 828                         unsigned long freecount = 0;
 829                         struct free_area *area;
 830                         struct list_head *curr;
 831
 832                         area = &(zone->free_area[order]);
 833
 834                         list_for_each(curr, &area->free_list[mtype])
 835                                 freecount++;
 836                         seq_printf(m, "%6lu ", freecount);
 837                 }
 838                 seq_putc(m, '\n');
 839         }
 840 }
 841
 842 /* Print out the free pages at each order for each migatetype */
 843 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 844 {
 845         int order;
 846         pg_data_t *pgdat = (pg_data_t *)arg;
 847
 848         /* Print header */
 849         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 850         for (order = 0; order < MAX_ORDER; ++order)
 851                 seq_printf(m, "%6d ", order);
 852         seq_putc(m, '\n');
 853
 854         walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 855
 856         return 0;
 857 }
 858
 859 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 860                                         pg_data_t *pgdat, struct zone *zone)
 861 {
 862         int mtype;
 863         unsigned long pfn;
 864         unsigned long start_pfn = zone->zone_start_pfn;
 865         unsigned long end_pfn = start_pfn + zone->spanned_pages;
 866         unsigned long count[MIGRATE_TYPES] = { 0, };
 867
 868         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 869                 struct page *page;
 870
 871                 if (!pfn_valid(pfn))
 872                         continue;
 873
 874                 page = pfn_to_page(pfn);
 875
 876                 /* Watch for unexpected holes punched in the memmap */
 877                 if (!memmap_valid_within(pfn, page, zone))
 878                         continue;
 879
 880                 mtype = get_pageblock_migratetype(page);
 881
 882                 if (mtype < MIGRATE_TYPES)
 883                         count[mtype]++;
 884         }
 885
 886         /* Print counts */
 887         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 888         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 889                 seq_printf(m, "%12lu ", count[mtype]);
 890         seq_putc(m, '\n');
 891 }
 892
 893 /* Print out the free pages at each order for each migratetype */
 894 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 895 {
 896         int mtype;
 897         pg_data_t *pgdat = (pg_data_t *)arg;
 898
 899         seq_printf(m, "\n%-23s", "Number of blocks type ");
 900         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 901                 seq_printf(m, "%12s ", migratetype_names[mtype]);
 902         seq_putc(m, '\n');
 903         walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 904
 905         return 0;
 906 }
 907
 908 /*
 909  * This prints out statistics in relation to grouping pages by mobility.
 910  * It is expensive to collect so do not constantly read the file.
 911  */
 912 static int pagetypeinfo_show(struct seq_file *m, void *arg)
 913 {
 914         pg_data_t *pgdat = (pg_data_t *)arg;
 915
 916         /* check memoryless node */
 917         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
 918                 return 0;
 919
 920         seq_printf(m, "Page block order: %d\n", pageblock_order);
 921         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 922         seq_putc(m, '\n');
 923         pagetypeinfo_showfree(m, pgdat);
 924         pagetypeinfo_showblockcount(m, pgdat);
 925
 926         return 0;
 927 }
 928
 929 static const struct seq_operations fragmentation_op = {
 930         .start  = frag_start,
 931         .next   = frag_next,
 932         .stop   = frag_stop,
 933         .show   = frag_show,
 934 };
 935
 936 static int fragmentation_open(struct inode *inode, struct file *file)
 937 {
 938         return seq_open(file, &fragmentation_op);
 939 }
 940
 941 static const struct file_operations fragmentation_file_operations = {
 942         .open           = fragmentation_open,
 943         .read           = seq_read,
 944         .llseek         = seq_lseek,
 945         .release        = seq_release,
 946 };
 947
 948 static const struct seq_operations pagetypeinfo_op = {
 949         .start  = frag_start,
 950         .next   = frag_next,
 951         .stop   = frag_stop,
 952         .show   = pagetypeinfo_show,
 953 };
 954
 955 static int pagetypeinfo_open(struct inode *inode, struct file *file)
 956 {
 957         return seq_open(file, &pagetypeinfo_op);
 958 }
 959
 960 static const struct file_operations pagetypeinfo_file_ops = {
 961         .open           = pagetypeinfo_open,
 962         .read           = seq_read,
 963         .llseek         = seq_lseek,
 964         .release        = seq_release,
 965 };
 966
 967 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 968                                                         struct zone *zone)
 969 {
 970         int i;
 971         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
 972         seq_printf(m,
 973                    "\n  pages free     %lu"
 974                    "\n        min      %lu"
 975                    "\n        low      %lu"
 976                    "\n        high     %lu"
 977                    "\n        scanned  %lu"
 978                    "\n        spanned  %lu"
 979                    "\n        present  %lu",
 980                    zone_page_state(zone, NR_FREE_PAGES),
 981                    min_wmark_pages(zone),
 982                    low_wmark_pages(zone),
 983                    high_wmark_pages(zone),
 984                    zone->pages_scanned,
 985                    zone->spanned_pages,
 986                    zone->present_pages);
 987
 988         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 989                 seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
 990                                 zone_page_state(zone, i));
 991
 992         seq_printf(m,
 993                    "\n        protection: (%lu",
 994                    zone->lowmem_reserve[0]);
 995         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
 996                 seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
 997         seq_printf(m,
 998                    ")"
 999                    "\n  pagesets");
1000         for_each_online_cpu(i) {
1001                 struct per_cpu_pageset *pageset;
1002
1003                 pageset = per_cpu_ptr(zone->pageset, i);
1004                 seq_printf(m,
1005                            "\n    cpu: %i"
1006                            "\n              count: %i"
1007                            "\n              high:  %i"
1008                            "\n              batch: %i",
1009                            i,
1010                            pageset->pcp.count,
1011                            pageset->pcp.high,
1012                            pageset->pcp.batch);
1013 #ifdef CONFIG_SMP
1014                 seq_printf(m, "\n  vm stats threshold: %d",
1015                                 pageset->stat_threshold);
1016 #endif
1017         }
1018         seq_printf(m,
1019                    "\n  all_unreclaimable: %u"
1020                    "\n  start_pfn:         %lu"
1021                    "\n  inactive_ratio:    %u",
1022                    zone->all_unreclaimable,
1023                    zone->zone_start_pfn,
1024                    zone->inactive_ratio);
1025         seq_putc(m, '\n');
1026 }
1027
1028 /*
1029  * Output information about zones in @pgdat.
1030  */
1031 static int zoneinfo_show(struct seq_file *m, void *arg)
1032 {
1033         pg_data_t *pgdat = (pg_data_t *)arg;
1034         walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1035         return 0;
1036 }
1037
1038 static const struct seq_operations zoneinfo_op = {
1039         .start  = frag_start, /* iterate over all zones. The same as in
1040                                * fragmentation. */
1041         .next   = frag_next,
1042         .stop   = frag_stop,
1043         .show   = zoneinfo_show,
1044 };
1045
1046 static int zoneinfo_open(struct inode *inode, struct file *file)
1047 {
1048         return seq_open(file, &zoneinfo_op);
1049 }
1050
1051 static const struct file_operations proc_zoneinfo_file_operations = {
1052         .open           = zoneinfo_open,
1053         .read           = seq_read,
1054         .llseek         = seq_lseek,
1055         .release        = seq_release,
1056 };
1057
1058 enum writeback_stat_item {
1059         NR_DIRTY_THRESHOLD,
1060         NR_DIRTY_BG_THRESHOLD,
1061         NR_VM_WRITEBACK_STAT_ITEMS,
1062 };
1063
1064 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1065 {
1066         unsigned long *v;
1067         int i, stat_items_size;
1068
1069         if (*pos >= ARRAY_SIZE(vmstat_text))
1070                 return NULL;
1071         stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1072                           NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1073
1074 #ifdef CONFIG_VM_EVENT_COUNTERS
1075         stat_items_size += sizeof(struct vm_event_state);
1076 #endif
1077
1078         v = kmalloc(stat_items_size, GFP_KERNEL);
1079         m->private = v;
1080         if (!v)
1081                 return ERR_PTR(-ENOMEM);
1082         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1083                 v[i] = global_page_state(i);
1084         v += NR_VM_ZONE_STAT_ITEMS;
1085
1086         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1087                             v + NR_DIRTY_THRESHOLD);
1088         v += NR_VM_WRITEBACK_STAT_ITEMS;
1089
1090 #ifdef CONFIG_VM_EVENT_COUNTERS
1091         all_vm_events(v);
1092         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1093         v[PGPGOUT] /= 2;
1094 #endif
1095         return (unsigned long *)m->private + *pos;
1096 }
1097
1098 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1099 {
1100         (*pos)++;
1101         if (*pos >= ARRAY_SIZE(vmstat_text))
1102                 return NULL;
1103         return (unsigned long *)m->private + *pos;
1104 }
1105
1106 static int vmstat_show(struct seq_file *m, void *arg)
1107 {
1108         unsigned long *l = arg;
1109         unsigned long off = l - (unsigned long *)m->private;
1110
1111         seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1112         return 0;
1113 }
1114
1115 static void vmstat_stop(struct seq_file *m, void *arg)
1116 {
1117         kfree(m->private);
1118         m->private = NULL;
1119 }
1120
1121 static const struct seq_operations vmstat_op = {
1122         .start  = vmstat_start,
1123         .next   = vmstat_next,
1124         .stop   = vmstat_stop,
1125         .show   = vmstat_show,
1126 };
1127
1128 static int vmstat_open(struct inode *inode, struct file *file)
1129 {
1130         return seq_open(file, &vmstat_op);
1131 }
1132
1133 static const struct file_operations proc_vmstat_file_operations = {
1134         .open           = vmstat_open,
1135         .read           = seq_read,
1136         .llseek         = seq_lseek,
1137         .release        = seq_release,
1138 };
1139 #endif /* CONFIG_PROC_FS */
1140
1141 #ifdef CONFIG_SMP
1142 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1143 int sysctl_stat_interval __read_mostly = HZ;
1144
1145 static void vmstat_update(struct work_struct *w)
1146 {
1147         refresh_cpu_vm_stats(smp_processor_id());
1148         schedule_delayed_work(&__get_cpu_var(vmstat_work),
1149                 round_jiffies_relative(sysctl_stat_interval));
1150 }
1151
1152 static void __cpuinit start_cpu_timer(int cpu)
1153 {
1154         struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1155
1156         INIT_DELAYED_WORK_DEFERRABLE(work, vmstat_update);
1157         schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1158 }
1159
1160 /*
1161  * Use the cpu notifier to insure that the thresholds are recalculated
1162  * when necessary.
1163  */
1164 static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1165                 unsigned long action,
1166                 void *hcpu)
1167 {
1168         long cpu = (long)hcpu;
1169
1170         switch (action) {
1171         case CPU_ONLINE:
1172         case CPU_ONLINE_FROZEN:
1173                 refresh_zone_stat_thresholds();
1174                 start_cpu_timer(cpu);
1175                 node_set_state(cpu_to_node(cpu), N_CPU);
1176                 break;
1177         case CPU_DOWN_PREPARE:
1178         case CPU_DOWN_PREPARE_FROZEN:
1179                 cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1180                 per_cpu(vmstat_work, cpu).work.func = NULL;
1181                 break;
1182         case CPU_DOWN_FAILED:
1183         case CPU_DOWN_FAILED_FROZEN:
1184                 start_cpu_timer(cpu);
1185                 break;
1186         case CPU_DEAD:
1187         case CPU_DEAD_FROZEN:
1188                 refresh_zone_stat_thresholds();
1189                 break;
1190         default:
1191                 break;
1192         }
1193         return NOTIFY_OK;
1194 }
1195
1196 static struct notifier_block __cpuinitdata vmstat_notifier =
1197         { &vmstat_cpuup_callback, NULL, 0 };
1198 #endif
1199
1200 static int __init setup_vmstat(void)
1201 {
1202 #ifdef CONFIG_SMP
1203         int cpu;
1204
1205         register_cpu_notifier(&vmstat_notifier);
1206
1207         for_each_online_cpu(cpu)
1208                 start_cpu_timer(cpu);
1209 #endif
1210 #ifdef CONFIG_PROC_FS
1211         proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1212         proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1213         proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1214         proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1215 #endif
1216         return 0;
1217 }
1218 module_init(setup_vmstat)
1219
1220 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1221 #include <linux/debugfs.h>
1222
1223 static struct dentry *extfrag_debug_root;
1224
1225 /*
1226  * Return an index indicating how much of the available free memory is
1227  * unusable for an allocation of the requested size.
1228  */
1229 static int unusable_free_index(unsigned int order,
1230                                 struct contig_page_info *info)
1231 {
1232         /* No free memory is interpreted as all free memory is unusable */
1233         if (info->free_pages == 0)
1234                 return 1000;
1235
1236         /*
1237          * Index should be a value between 0 and 1. Return a value to 3
1238          * decimal places.
1239          *
1240          * 0 => no fragmentation
1241          * 1 => high fragmentation
1242          */
1243         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1244
1245 }
1246
1247 static void unusable_show_print(struct seq_file *m,
1248                                         pg_data_t *pgdat, struct zone *zone)
1249 {
1250         unsigned int order;
1251         int index;
1252         struct contig_page_info info;
1253
1254         seq_printf(m, "Node %d, zone %8s ",
1255                                 pgdat->node_id,
1256                                 zone->name);
1257         for (order = 0; order < MAX_ORDER; ++order) {
1258                 fill_contig_page_info(zone, order, &info);
1259                 index = unusable_free_index(order, &info);
1260                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1261         }
1262
1263         seq_putc(m, '\n');
1264 }
1265
1266 /*
1267  * Display unusable free space index
1268  *
1269  * The unusable free space index measures how much of the available free
1270  * memory cannot be used to satisfy an allocation of a given size and is a
1271  * value between 0 and 1. The higher the value, the more of free memory is
1272  * unusable and by implication, the worse the external fragmentation is. This
1273  * can be expressed as a percentage by multiplying by 100.
1274  */
1275 static int unusable_show(struct seq_file *m, void *arg)
1276 {
1277         pg_data_t *pgdat = (pg_data_t *)arg;
1278
1279         /* check memoryless node */
1280         if (!node_state(pgdat->node_id, N_HIGH_MEMORY))
1281                 return 0;
1282
1283         walk_zones_in_node(m, pgdat, unusable_show_print);
1284
1285         return 0;
1286 }
1287
1288 static const struct seq_operations unusable_op = {
1289         .start  = frag_start,
1290         .next   = frag_next,
1291         .stop   = frag_stop,
1292         .show   = unusable_show,
1293 };
1294
1295 static int unusable_open(struct inode *inode, struct file *file)
1296 {
1297         return seq_open(file, &unusable_op);
1298 }
1299
1300 static const struct file_operations unusable_file_ops = {
1301         .open           = unusable_open,
1302         .read           = seq_read,
1303         .llseek         = seq_lseek,
1304         .release        = seq_release,
1305 };
1306
1307 static void extfrag_show_print(struct seq_file *m,
1308                                         pg_data_t *pgdat, struct zone *zone)
1309 {
1310         unsigned int order;
1311         int index;
1312
1313         /* Alloc on stack as interrupts are disabled for zone walk */
1314         struct contig_page_info info;
1315
1316         seq_printf(m, "Node %d, zone %8s ",
1317                                 pgdat->node_id,
1318                                 zone->name);
1319         for (order = 0; order < MAX_ORDER; ++order) {
1320                 fill_contig_page_info(zone, order, &info);
1321                 index = __fragmentation_index(order, &info);
1322                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1323         }
1324
1325         seq_putc(m, '\n');
1326 }
1327
1328 /*
1329  * Display fragmentation index for orders that allocations would fail for
1330  */
1331 static int extfrag_show(struct seq_file *m, void *arg)
1332 {
1333         pg_data_t *pgdat = (pg_data_t *)arg;
1334
1335         walk_zones_in_node(m, pgdat, extfrag_show_print);
1336
1337         return 0;
1338 }
1339
1340 static const struct seq_operations extfrag_op = {
1341         .start  = frag_start,
1342         .next   = frag_next,
1343         .stop   = frag_stop,
1344         .show   = extfrag_show,
1345 };
1346
1347 static int extfrag_open(struct inode *inode, struct file *file)
1348 {
1349         return seq_open(file, &extfrag_op);
1350 }
1351
1352 static const struct file_operations extfrag_file_ops = {
1353         .open           = extfrag_open,
1354         .read           = seq_read,
1355         .llseek         = seq_lseek,
1356         .release        = seq_release,
1357 };
1358
1359 static int __init extfrag_debug_init(void)
1360 {
1361         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1362         if (!extfrag_debug_root)
1363                 return -ENOMEM;
1364
1365         if (!debugfs_create_file("unusable_index", 0444,
1366                         extfrag_debug_root, NULL, &unusable_file_ops))
1367                 return -ENOMEM;
1368
1369         if (!debugfs_create_file("extfrag_index", 0444,
1370                         extfrag_debug_root, NULL, &extfrag_file_ops))
1371                 return -ENOMEM;
1372
1373         return 0;
1374 }
1375
1376 module_init(extfrag_debug_init);
1377 #endif