linux/mm/vmstat.c
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   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
  24DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
  25EXPORT_PER_CPU_SYMBOL(vm_event_states);
  26
  27static 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*/
  47void all_vm_events(unsigned long *ret)
  48{
  49        get_online_cpus();
  50        sum_vm_events(ret);
  51        put_online_cpus();
  52}
  53EXPORT_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 */
  62void 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 */
  81atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
  82EXPORT_SYMBOL(vm_stat);
  83
  84#ifdef CONFIG_SMP
  85
  86int 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
 110int 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->managed_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 */
 160void 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
 188void 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 */
 211void __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}
 229EXPORT_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 */
 254void __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
 270void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 271{
 272        __inc_zone_state(page_zone(page), item);
 273}
 274EXPORT_SYMBOL(__inc_zone_page_state);
 275
 276void __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
 292void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 293{
 294        __dec_zone_state(page_zone(page), item);
 295}
 296EXPORT_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*/
 311static 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
 349void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 350                                        int delta)
 351{
 352        mod_state(zone, item, delta, 0);
 353}
 354EXPORT_SYMBOL(mod_zone_page_state);
 355
 356void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 357{
 358        mod_state(zone, item, 1, 1);
 359}
 360
 361void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 362{
 363        mod_state(page_zone(page), item, 1, 1);
 364}
 365EXPORT_SYMBOL(inc_zone_page_state);
 366
 367void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 368{
 369        mod_state(page_zone(page), item, -1, -1);
 370}
 371EXPORT_SYMBOL(dec_zone_page_state);
 372#else
 373/*
 374 * Use interrupt disable to serialize counter updates
 375 */
 376void 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}
 385EXPORT_SYMBOL(mod_zone_page_state);
 386
 387void 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
 396void 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}
 406EXPORT_SYMBOL(inc_zone_page_state);
 407
 408void 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}
 416EXPORT_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 */
 437void 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
 498void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
 499{
 500        int i;
 501
 502        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 503                if (pset->vm_stat_diff[i]) {
 504                        int v = pset->vm_stat_diff[i];
 505                        pset->vm_stat_diff[i] = 0;
 506                        atomic_long_add(v, &zone->vm_stat[i]);
 507                        atomic_long_add(v, &vm_stat[i]);
 508                }
 509}
 510#endif
 511
 512#ifdef CONFIG_NUMA
 513/*
 514 * zonelist = the list of zones passed to the allocator
 515 * z        = the zone from which the allocation occurred.
 516 *
 517 * Must be called with interrupts disabled.
 518 *
 519 * When __GFP_OTHER_NODE is set assume the node of the preferred
 520 * zone is the local node. This is useful for daemons who allocate
 521 * memory on behalf of other processes.
 522 */
 523void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 524{
 525        if (z->zone_pgdat == preferred_zone->zone_pgdat) {
 526                __inc_zone_state(z, NUMA_HIT);
 527        } else {
 528                __inc_zone_state(z, NUMA_MISS);
 529                __inc_zone_state(preferred_zone, NUMA_FOREIGN);
 530        }
 531        if (z->node == ((flags & __GFP_OTHER_NODE) ?
 532                        preferred_zone->node : numa_node_id()))
 533                __inc_zone_state(z, NUMA_LOCAL);
 534        else
 535                __inc_zone_state(z, NUMA_OTHER);
 536}
 537#endif
 538
 539#ifdef CONFIG_COMPACTION
 540
 541struct contig_page_info {
 542        unsigned long free_pages;
 543        unsigned long free_blocks_total;
 544        unsigned long free_blocks_suitable;
 545};
 546
 547/*
 548 * Calculate the number of free pages in a zone, how many contiguous
 549 * pages are free and how many are large enough to satisfy an allocation of
 550 * the target size. Note that this function makes no attempt to estimate
 551 * how many suitable free blocks there *might* be if MOVABLE pages were
 552 * migrated. Calculating that is possible, but expensive and can be
 553 * figured out from userspace
 554 */
 555static void fill_contig_page_info(struct zone *zone,
 556                                unsigned int suitable_order,
 557                                struct contig_page_info *info)
 558{
 559        unsigned int order;
 560
 561        info->free_pages = 0;
 562        info->free_blocks_total = 0;
 563        info->free_blocks_suitable = 0;
 564
 565        for (order = 0; order < MAX_ORDER; order++) {
 566                unsigned long blocks;
 567
 568                /* Count number of free blocks */
 569                blocks = zone->free_area[order].nr_free;
 570                info->free_blocks_total += blocks;
 571
 572                /* Count free base pages */
 573                info->free_pages += blocks << order;
 574
 575                /* Count the suitable free blocks */
 576                if (order >= suitable_order)
 577                        info->free_blocks_suitable += blocks <<
 578                                                (order - suitable_order);
 579        }
 580}
 581
 582/*
 583 * A fragmentation index only makes sense if an allocation of a requested
 584 * size would fail. If that is true, the fragmentation index indicates
 585 * whether external fragmentation or a lack of memory was the problem.
 586 * The value can be used to determine if page reclaim or compaction
 587 * should be used
 588 */
 589static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
 590{
 591        unsigned long requested = 1UL << order;
 592
 593        if (!info->free_blocks_total)
 594                return 0;
 595
 596        /* Fragmentation index only makes sense when a request would fail */
 597        if (info->free_blocks_suitable)
 598                return -1000;
 599
 600        /*
 601         * Index is between 0 and 1 so return within 3 decimal places
 602         *
 603         * 0 => allocation would fail due to lack of memory
 604         * 1 => allocation would fail due to fragmentation
 605         */
 606        return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
 607}
 608
 609/* Same as __fragmentation index but allocs contig_page_info on stack */
 610int fragmentation_index(struct zone *zone, unsigned int order)
 611{
 612        struct contig_page_info info;
 613
 614        fill_contig_page_info(zone, order, &info);
 615        return __fragmentation_index(order, &info);
 616}
 617#endif
 618
 619#if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
 620#include <linux/proc_fs.h>
 621#include <linux/seq_file.h>
 622
 623static char * const migratetype_names[MIGRATE_TYPES] = {
 624        "Unmovable",
 625        "Reclaimable",
 626        "Movable",
 627        "Reserve",
 628#ifdef CONFIG_CMA
 629        "CMA",
 630#endif
 631#ifdef CONFIG_MEMORY_ISOLATION
 632        "Isolate",
 633#endif
 634};
 635
 636static void *frag_start(struct seq_file *m, loff_t *pos)
 637{
 638        pg_data_t *pgdat;
 639        loff_t node = *pos;
 640        for (pgdat = first_online_pgdat();
 641             pgdat && node;
 642             pgdat = next_online_pgdat(pgdat))
 643                --node;
 644
 645        return pgdat;
 646}
 647
 648static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 649{
 650        pg_data_t *pgdat = (pg_data_t *)arg;
 651
 652        (*pos)++;
 653        return next_online_pgdat(pgdat);
 654}
 655
 656static void frag_stop(struct seq_file *m, void *arg)
 657{
 658}
 659
 660/* Walk all the zones in a node and print using a callback */
 661static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 662                void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 663{
 664        struct zone *zone;
 665        struct zone *node_zones = pgdat->node_zones;
 666        unsigned long flags;
 667
 668        for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 669                if (!populated_zone(zone))
 670                        continue;
 671
 672                spin_lock_irqsave(&zone->lock, flags);
 673                print(m, pgdat, zone);
 674                spin_unlock_irqrestore(&zone->lock, flags);
 675        }
 676}
 677#endif
 678
 679#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 680#ifdef CONFIG_ZONE_DMA
 681#define TEXT_FOR_DMA(xx) xx "_dma",
 682#else
 683#define TEXT_FOR_DMA(xx)
 684#endif
 685
 686#ifdef CONFIG_ZONE_DMA32
 687#define TEXT_FOR_DMA32(xx) xx "_dma32",
 688#else
 689#define TEXT_FOR_DMA32(xx)
 690#endif
 691
 692#ifdef CONFIG_HIGHMEM
 693#define TEXT_FOR_HIGHMEM(xx) xx "_high",
 694#else
 695#define TEXT_FOR_HIGHMEM(xx)
 696#endif
 697
 698#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 699                                        TEXT_FOR_HIGHMEM(xx) xx "_movable",
 700
 701const char * const vmstat_text[] = {
 702        /* Zoned VM counters */
 703        "nr_free_pages",
 704        "nr_inactive_anon",
 705        "nr_active_anon",
 706        "nr_inactive_file",
 707        "nr_active_file",
 708        "nr_unevictable",
 709        "nr_mlock",
 710        "nr_anon_pages",
 711        "nr_mapped",
 712        "nr_file_pages",
 713        "nr_dirty",
 714        "nr_writeback",
 715        "nr_slab_reclaimable",
 716        "nr_slab_unreclaimable",
 717        "nr_page_table_pages",
 718        "nr_kernel_stack",
 719        "nr_unstable",
 720        "nr_bounce",
 721        "nr_vmscan_write",
 722        "nr_vmscan_immediate_reclaim",
 723        "nr_writeback_temp",
 724        "nr_isolated_anon",
 725        "nr_isolated_file",
 726        "nr_shmem",
 727        "nr_dirtied",
 728        "nr_written",
 729
 730#ifdef CONFIG_NUMA
 731        "numa_hit",
 732        "numa_miss",
 733        "numa_foreign",
 734        "numa_interleave",
 735        "numa_local",
 736        "numa_other",
 737#endif
 738        "nr_anon_transparent_hugepages",
 739        "nr_free_cma",
 740        "nr_dirty_threshold",
 741        "nr_dirty_background_threshold",
 742
 743#ifdef CONFIG_VM_EVENT_COUNTERS
 744        "pgpgin",
 745        "pgpgout",
 746        "pswpin",
 747        "pswpout",
 748
 749        TEXTS_FOR_ZONES("pgalloc")
 750
 751        "pgfree",
 752        "pgactivate",
 753        "pgdeactivate",
 754
 755        "pgfault",
 756        "pgmajfault",
 757
 758        TEXTS_FOR_ZONES("pgrefill")
 759        TEXTS_FOR_ZONES("pgsteal_kswapd")
 760        TEXTS_FOR_ZONES("pgsteal_direct")
 761        TEXTS_FOR_ZONES("pgscan_kswapd")
 762        TEXTS_FOR_ZONES("pgscan_direct")
 763        "pgscan_direct_throttle",
 764
 765#ifdef CONFIG_NUMA
 766        "zone_reclaim_failed",
 767#endif
 768        "pginodesteal",
 769        "slabs_scanned",
 770        "kswapd_inodesteal",
 771        "kswapd_low_wmark_hit_quickly",
 772        "kswapd_high_wmark_hit_quickly",
 773        "pageoutrun",
 774        "allocstall",
 775
 776        "pgrotated",
 777
 778#ifdef CONFIG_NUMA_BALANCING
 779        "numa_pte_updates",
 780        "numa_hint_faults",
 781        "numa_hint_faults_local",
 782        "numa_pages_migrated",
 783#endif
 784#ifdef CONFIG_MIGRATION
 785        "pgmigrate_success",
 786        "pgmigrate_fail",
 787#endif
 788#ifdef CONFIG_COMPACTION
 789        "compact_migrate_scanned",
 790        "compact_free_scanned",
 791        "compact_isolated",
 792        "compact_stall",
 793        "compact_fail",
 794        "compact_success",
 795#endif
 796
 797#ifdef CONFIG_HUGETLB_PAGE
 798        "htlb_buddy_alloc_success",
 799        "htlb_buddy_alloc_fail",
 800#endif
 801        "unevictable_pgs_culled",
 802        "unevictable_pgs_scanned",
 803        "unevictable_pgs_rescued",
 804        "unevictable_pgs_mlocked",
 805        "unevictable_pgs_munlocked",
 806        "unevictable_pgs_cleared",
 807        "unevictable_pgs_stranded",
 808
 809#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 810        "thp_fault_alloc",
 811        "thp_fault_fallback",
 812        "thp_collapse_alloc",
 813        "thp_collapse_alloc_failed",
 814        "thp_split",
 815        "thp_zero_page_alloc",
 816        "thp_zero_page_alloc_failed",
 817#endif
 818
 819#endif /* CONFIG_VM_EVENTS_COUNTERS */
 820};
 821#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 822
 823
 824#ifdef CONFIG_PROC_FS
 825static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 826                                                struct zone *zone)
 827{
 828        int order;
 829
 830        seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 831        for (order = 0; order < MAX_ORDER; ++order)
 832                seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 833        seq_putc(m, '\n');
 834}
 835
 836/*
 837 * This walks the free areas for each zone.
 838 */
 839static int frag_show(struct seq_file *m, void *arg)
 840{
 841        pg_data_t *pgdat = (pg_data_t *)arg;
 842        walk_zones_in_node(m, pgdat, frag_show_print);
 843        return 0;
 844}
 845
 846static void pagetypeinfo_showfree_print(struct seq_file *m,
 847                                        pg_data_t *pgdat, struct zone *zone)
 848{
 849        int order, mtype;
 850
 851        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 852                seq_printf(m, "Node %4d, zone %8s, type %12s ",
 853                                        pgdat->node_id,
 854                                        zone->name,
 855                                        migratetype_names[mtype]);
 856                for (order = 0; order < MAX_ORDER; ++order) {
 857                        unsigned long freecount = 0;
 858                        struct free_area *area;
 859                        struct list_head *curr;
 860
 861                        area = &(zone->free_area[order]);
 862
 863                        list_for_each(curr, &area->free_list[mtype])
 864                                freecount++;
 865                        seq_printf(m, "%6lu ", freecount);
 866                }
 867                seq_putc(m, '\n');
 868        }
 869}
 870
 871/* Print out the free pages at each order for each migatetype */
 872static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 873{
 874        int order;
 875        pg_data_t *pgdat = (pg_data_t *)arg;
 876
 877        /* Print header */
 878        seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 879        for (order = 0; order < MAX_ORDER; ++order)
 880                seq_printf(m, "%6d ", order);
 881        seq_putc(m, '\n');
 882
 883        walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 884
 885        return 0;
 886}
 887
 888static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 889                                        pg_data_t *pgdat, struct zone *zone)
 890{
 891        int mtype;
 892        unsigned long pfn;
 893        unsigned long start_pfn = zone->zone_start_pfn;
 894        unsigned long end_pfn = zone_end_pfn(zone);
 895        unsigned long count[MIGRATE_TYPES] = { 0, };
 896
 897        for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 898                struct page *page;
 899
 900                if (!pfn_valid(pfn))
 901                        continue;
 902
 903                page = pfn_to_page(pfn);
 904
 905                /* Watch for unexpected holes punched in the memmap */
 906                if (!memmap_valid_within(pfn, page, zone))
 907                        continue;
 908
 909                mtype = get_pageblock_migratetype(page);
 910
 911                if (mtype < MIGRATE_TYPES)
 912                        count[mtype]++;
 913        }
 914
 915        /* Print counts */
 916        seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 917        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 918                seq_printf(m, "%12lu ", count[mtype]);
 919        seq_putc(m, '\n');
 920}
 921
 922/* Print out the free pages at each order for each migratetype */
 923static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 924{
 925        int mtype;
 926        pg_data_t *pgdat = (pg_data_t *)arg;
 927
 928        seq_printf(m, "\n%-23s", "Number of blocks type ");
 929        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 930                seq_printf(m, "%12s ", migratetype_names[mtype]);
 931        seq_putc(m, '\n');
 932        walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 933
 934        return 0;
 935}
 936
 937/*
 938 * This prints out statistics in relation to grouping pages by mobility.
 939 * It is expensive to collect so do not constantly read the file.
 940 */
 941static int pagetypeinfo_show(struct seq_file *m, void *arg)
 942{
 943        pg_data_t *pgdat = (pg_data_t *)arg;
 944
 945        /* check memoryless node */
 946        if (!node_state(pgdat->node_id, N_MEMORY))
 947                return 0;
 948
 949        seq_printf(m, "Page block order: %d\n", pageblock_order);
 950        seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 951        seq_putc(m, '\n');
 952        pagetypeinfo_showfree(m, pgdat);
 953        pagetypeinfo_showblockcount(m, pgdat);
 954
 955        return 0;
 956}
 957
 958static const struct seq_operations fragmentation_op = {
 959        .start  = frag_start,
 960        .next   = frag_next,
 961        .stop   = frag_stop,
 962        .show   = frag_show,
 963};
 964
 965static int fragmentation_open(struct inode *inode, struct file *file)
 966{
 967        return seq_open(file, &fragmentation_op);
 968}
 969
 970static const struct file_operations fragmentation_file_operations = {
 971        .open           = fragmentation_open,
 972        .read           = seq_read,
 973        .llseek         = seq_lseek,
 974        .release        = seq_release,
 975};
 976
 977static const struct seq_operations pagetypeinfo_op = {
 978        .start  = frag_start,
 979        .next   = frag_next,
 980        .stop   = frag_stop,
 981        .show   = pagetypeinfo_show,
 982};
 983
 984static int pagetypeinfo_open(struct inode *inode, struct file *file)
 985{
 986        return seq_open(file, &pagetypeinfo_op);
 987}
 988
 989static const struct file_operations pagetypeinfo_file_ops = {
 990        .open           = pagetypeinfo_open,
 991        .read           = seq_read,
 992        .llseek         = seq_lseek,
 993        .release        = seq_release,
 994};
 995
 996static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 997                                                        struct zone *zone)
 998{
 999        int i;
1000        seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1001        seq_printf(m,
1002                   "\n  pages free     %lu"
1003                   "\n        min      %lu"
1004                   "\n        low      %lu"
1005                   "\n        high     %lu"
1006                   "\n        scanned  %lu"
1007                   "\n        spanned  %lu"
1008                   "\n        present  %lu"
1009                   "\n        managed  %lu",
1010                   zone_page_state(zone, NR_FREE_PAGES),
1011                   min_wmark_pages(zone),
1012                   low_wmark_pages(zone),
1013                   high_wmark_pages(zone),
1014                   zone->pages_scanned,
1015                   zone->spanned_pages,
1016                   zone->present_pages,
1017                   zone->managed_pages);
1018
1019        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1020                seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
1021                                zone_page_state(zone, i));
1022
1023        seq_printf(m,
1024                   "\n        protection: (%lu",
1025                   zone->lowmem_reserve[0]);
1026        for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1027                seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
1028        seq_printf(m,
1029                   ")"
1030                   "\n  pagesets");
1031        for_each_online_cpu(i) {
1032                struct per_cpu_pageset *pageset;
1033
1034                pageset = per_cpu_ptr(zone->pageset, i);
1035                seq_printf(m,
1036                           "\n    cpu: %i"
1037                           "\n              count: %i"
1038                           "\n              high:  %i"
1039                           "\n              batch: %i",
1040                           i,
1041                           pageset->pcp.count,
1042                           pageset->pcp.high,
1043                           pageset->pcp.batch);
1044#ifdef CONFIG_SMP
1045                seq_printf(m, "\n  vm stats threshold: %d",
1046                                pageset->stat_threshold);
1047#endif
1048        }
1049        seq_printf(m,
1050                   "\n  all_unreclaimable: %u"
1051                   "\n  start_pfn:         %lu"
1052                   "\n  inactive_ratio:    %u",
1053                   zone->all_unreclaimable,
1054                   zone->zone_start_pfn,
1055                   zone->inactive_ratio);
1056        seq_putc(m, '\n');
1057}
1058
1059/*
1060 * Output information about zones in @pgdat.
1061 */
1062static int zoneinfo_show(struct seq_file *m, void *arg)
1063{
1064        pg_data_t *pgdat = (pg_data_t *)arg;
1065        walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1066        return 0;
1067}
1068
1069static const struct seq_operations zoneinfo_op = {
1070        .start  = frag_start, /* iterate over all zones. The same as in
1071                               * fragmentation. */
1072        .next   = frag_next,
1073        .stop   = frag_stop,
1074        .show   = zoneinfo_show,
1075};
1076
1077static int zoneinfo_open(struct inode *inode, struct file *file)
1078{
1079        return seq_open(file, &zoneinfo_op);
1080}
1081
1082static const struct file_operations proc_zoneinfo_file_operations = {
1083        .open           = zoneinfo_open,
1084        .read           = seq_read,
1085        .llseek         = seq_lseek,
1086        .release        = seq_release,
1087};
1088
1089enum writeback_stat_item {
1090        NR_DIRTY_THRESHOLD,
1091        NR_DIRTY_BG_THRESHOLD,
1092        NR_VM_WRITEBACK_STAT_ITEMS,
1093};
1094
1095static void *vmstat_start(struct seq_file *m, loff_t *pos)
1096{
1097        unsigned long *v;
1098        int i, stat_items_size;
1099
1100        if (*pos >= ARRAY_SIZE(vmstat_text))
1101                return NULL;
1102        stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1103                          NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1104
1105#ifdef CONFIG_VM_EVENT_COUNTERS
1106        stat_items_size += sizeof(struct vm_event_state);
1107#endif
1108
1109        v = kmalloc(stat_items_size, GFP_KERNEL);
1110        m->private = v;
1111        if (!v)
1112                return ERR_PTR(-ENOMEM);
1113        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1114                v[i] = global_page_state(i);
1115        v += NR_VM_ZONE_STAT_ITEMS;
1116
1117        global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1118                            v + NR_DIRTY_THRESHOLD);
1119        v += NR_VM_WRITEBACK_STAT_ITEMS;
1120
1121#ifdef CONFIG_VM_EVENT_COUNTERS
1122        all_vm_events(v);
1123        v[PGPGIN] /= 2;         /* sectors -> kbytes */
1124        v[PGPGOUT] /= 2;
1125#endif
1126        return (unsigned long *)m->private + *pos;
1127}
1128
1129static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1130{
1131        (*pos)++;
1132        if (*pos >= ARRAY_SIZE(vmstat_text))
1133                return NULL;
1134        return (unsigned long *)m->private + *pos;
1135}
1136
1137static int vmstat_show(struct seq_file *m, void *arg)
1138{
1139        unsigned long *l = arg;
1140        unsigned long off = l - (unsigned long *)m->private;
1141
1142        seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1143        return 0;
1144}
1145
1146static void vmstat_stop(struct seq_file *m, void *arg)
1147{
1148        kfree(m->private);
1149        m->private = NULL;
1150}
1151
1152static const struct seq_operations vmstat_op = {
1153        .start  = vmstat_start,
1154        .next   = vmstat_next,
1155        .stop   = vmstat_stop,
1156        .show   = vmstat_show,
1157};
1158
1159static int vmstat_open(struct inode *inode, struct file *file)
1160{
1161        return seq_open(file, &vmstat_op);
1162}
1163
1164static const struct file_operations proc_vmstat_file_operations = {
1165        .open           = vmstat_open,
1166        .read           = seq_read,
1167        .llseek         = seq_lseek,
1168        .release        = seq_release,
1169};
1170#endif /* CONFIG_PROC_FS */
1171
1172#ifdef CONFIG_SMP
1173static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1174int sysctl_stat_interval __read_mostly = HZ;
1175
1176static void vmstat_update(struct work_struct *w)
1177{
1178        refresh_cpu_vm_stats(smp_processor_id());
1179        schedule_delayed_work(&__get_cpu_var(vmstat_work),
1180                round_jiffies_relative(sysctl_stat_interval));
1181}
1182
1183static void __cpuinit start_cpu_timer(int cpu)
1184{
1185        struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1186
1187        INIT_DEFERRABLE_WORK(work, vmstat_update);
1188        schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1189}
1190
1191/*
1192 * Use the cpu notifier to insure that the thresholds are recalculated
1193 * when necessary.
1194 */
1195static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1196                unsigned long action,
1197                void *hcpu)
1198{
1199        long cpu = (long)hcpu;
1200
1201        switch (action) {
1202        case CPU_ONLINE:
1203        case CPU_ONLINE_FROZEN:
1204                refresh_zone_stat_thresholds();
1205                start_cpu_timer(cpu);
1206                node_set_state(cpu_to_node(cpu), N_CPU);
1207                break;
1208        case CPU_DOWN_PREPARE:
1209        case CPU_DOWN_PREPARE_FROZEN:
1210                cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1211                per_cpu(vmstat_work, cpu).work.func = NULL;
1212                break;
1213        case CPU_DOWN_FAILED:
1214        case CPU_DOWN_FAILED_FROZEN:
1215                start_cpu_timer(cpu);
1216                break;
1217        case CPU_DEAD:
1218        case CPU_DEAD_FROZEN:
1219                refresh_zone_stat_thresholds();
1220                break;
1221        default:
1222                break;
1223        }
1224        return NOTIFY_OK;
1225}
1226
1227static struct notifier_block __cpuinitdata vmstat_notifier =
1228        { &vmstat_cpuup_callback, NULL, 0 };
1229#endif
1230
1231static int __init setup_vmstat(void)
1232{
1233#ifdef CONFIG_SMP
1234        int cpu;
1235
1236        register_cpu_notifier(&vmstat_notifier);
1237
1238        for_each_online_cpu(cpu)
1239                start_cpu_timer(cpu);
1240#endif
1241#ifdef CONFIG_PROC_FS
1242        proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1243        proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1244        proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1245        proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1246#endif
1247        return 0;
1248}
1249module_init(setup_vmstat)
1250
1251#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1252#include <linux/debugfs.h>
1253
1254
1255/*
1256 * Return an index indicating how much of the available free memory is
1257 * unusable for an allocation of the requested size.
1258 */
1259static int unusable_free_index(unsigned int order,
1260                                struct contig_page_info *info)
1261{
1262        /* No free memory is interpreted as all free memory is unusable */
1263        if (info->free_pages == 0)
1264                return 1000;
1265
1266        /*
1267         * Index should be a value between 0 and 1. Return a value to 3
1268         * decimal places.
1269         *
1270         * 0 => no fragmentation
1271         * 1 => high fragmentation
1272         */
1273        return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1274
1275}
1276
1277static void unusable_show_print(struct seq_file *m,
1278                                        pg_data_t *pgdat, struct zone *zone)
1279{
1280        unsigned int order;
1281        int index;
1282        struct contig_page_info info;
1283
1284        seq_printf(m, "Node %d, zone %8s ",
1285                                pgdat->node_id,
1286                                zone->name);
1287        for (order = 0; order < MAX_ORDER; ++order) {
1288                fill_contig_page_info(zone, order, &info);
1289                index = unusable_free_index(order, &info);
1290                seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1291        }
1292
1293        seq_putc(m, '\n');
1294}
1295
1296/*
1297 * Display unusable free space index
1298 *
1299 * The unusable free space index measures how much of the available free
1300 * memory cannot be used to satisfy an allocation of a given size and is a
1301 * value between 0 and 1. The higher the value, the more of free memory is
1302 * unusable and by implication, the worse the external fragmentation is. This
1303 * can be expressed as a percentage by multiplying by 100.
1304 */
1305static int unusable_show(struct seq_file *m, void *arg)
1306{
1307        pg_data_t *pgdat = (pg_data_t *)arg;
1308
1309        /* check memoryless node */
1310        if (!node_state(pgdat->node_id, N_MEMORY))
1311                return 0;
1312
1313        walk_zones_in_node(m, pgdat, unusable_show_print);
1314
1315        return 0;
1316}
1317
1318static const struct seq_operations unusable_op = {
1319        .start  = frag_start,
1320        .next   = frag_next,
1321        .stop   = frag_stop,
1322        .show   = unusable_show,
1323};
1324
1325static int unusable_open(struct inode *inode, struct file *file)
1326{
1327        return seq_open(file, &unusable_op);
1328}
1329
1330static const struct file_operations unusable_file_ops = {
1331        .open           = unusable_open,
1332        .read           = seq_read,
1333        .llseek         = seq_lseek,
1334        .release        = seq_release,
1335};
1336
1337static void extfrag_show_print(struct seq_file *m,
1338                                        pg_data_t *pgdat, struct zone *zone)
1339{
1340        unsigned int order;
1341        int index;
1342
1343        /* Alloc on stack as interrupts are disabled for zone walk */
1344        struct contig_page_info info;
1345
1346        seq_printf(m, "Node %d, zone %8s ",
1347                                pgdat->node_id,
1348                                zone->name);
1349        for (order = 0; order < MAX_ORDER; ++order) {
1350                fill_contig_page_info(zone, order, &info);
1351                index = __fragmentation_index(order, &info);
1352                seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1353        }
1354
1355        seq_putc(m, '\n');
1356}
1357
1358/*
1359 * Display fragmentation index for orders that allocations would fail for
1360 */
1361static int extfrag_show(struct seq_file *m, void *arg)
1362{
1363        pg_data_t *pgdat = (pg_data_t *)arg;
1364
1365        walk_zones_in_node(m, pgdat, extfrag_show_print);
1366
1367        return 0;
1368}
1369
1370static const struct seq_operations extfrag_op = {
1371        .start  = frag_start,
1372        .next   = frag_next,
1373        .stop   = frag_stop,
1374        .show   = extfrag_show,
1375};
1376
1377static int extfrag_open(struct inode *inode, struct file *file)
1378{
1379        return seq_open(file, &extfrag_op);
1380}
1381
1382static const struct file_operations extfrag_file_ops = {
1383        .open           = extfrag_open,
1384        .read           = seq_read,
1385        .llseek         = seq_lseek,
1386        .release        = seq_release,
1387};
1388
1389static int __init extfrag_debug_init(void)
1390{
1391        struct dentry *extfrag_debug_root;
1392
1393        extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1394        if (!extfrag_debug_root)
1395                return -ENOMEM;
1396
1397        if (!debugfs_create_file("unusable_index", 0444,
1398                        extfrag_debug_root, NULL, &unusable_file_ops))
1399                goto fail;
1400
1401        if (!debugfs_create_file("extfrag_index", 0444,
1402                        extfrag_debug_root, NULL, &extfrag_file_ops))
1403                goto fail;
1404
1405        return 0;
1406fail:
1407        debugfs_remove_recursive(extfrag_debug_root);
1408        return -ENOMEM;
1409}
1410
1411module_init(extfrag_debug_init);
1412#endif
1413
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