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/*
  56 * Fold the foreign cpu events into our own.
  57 *
  58 * This is adding to the events on one processor
  59 * but keeps the global counts constant.
  60 */
  61void vm_events_fold_cpu(int cpu)
  62{
  63        struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
  64        int i;
  65
  66        for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
  67                count_vm_events(i, fold_state->event[i]);
  68                fold_state->event[i] = 0;
  69        }
  70}
  71
  72#endif /* CONFIG_VM_EVENT_COUNTERS */
  73
  74/*
  75 * Manage combined zone based / global counters
  76 *
  77 * vm_stat contains the global counters
  78 */
  79atomic_long_t vm_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
  80EXPORT_SYMBOL(vm_stat);
  81
  82#ifdef CONFIG_SMP
  83
  84int calculate_pressure_threshold(struct zone *zone)
  85{
  86        int threshold;
  87        int watermark_distance;
  88
  89        /*
  90         * As vmstats are not up to date, there is drift between the estimated
  91         * and real values. For high thresholds and a high number of CPUs, it
  92         * is possible for the min watermark to be breached while the estimated
  93         * value looks fine. The pressure threshold is a reduced value such
  94         * that even the maximum amount of drift will not accidentally breach
  95         * the min watermark
  96         */
  97        watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
  98        threshold = max(1, (int)(watermark_distance / num_online_cpus()));
  99
 100        /*
 101         * Maximum threshold is 125
 102         */
 103        threshold = min(125, threshold);
 104
 105        return threshold;
 106}
 107
 108int calculate_normal_threshold(struct zone *zone)
 109{
 110        int threshold;
 111        int mem;        /* memory in 128 MB units */
 112
 113        /*
 114         * The threshold scales with the number of processors and the amount
 115         * of memory per zone. More memory means that we can defer updates for
 116         * longer, more processors could lead to more contention.
 117         * fls() is used to have a cheap way of logarithmic scaling.
 118         *
 119         * Some sample thresholds:
 120         *
 121         * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
 122         * ------------------------------------------------------------------
 123         * 8            1               1       0.9-1 GB        4
 124         * 16           2               2       0.9-1 GB        4
 125         * 20           2               2       1-2 GB          5
 126         * 24           2               2       2-4 GB          6
 127         * 28           2               2       4-8 GB          7
 128         * 32           2               2       8-16 GB         8
 129         * 4            2               2       <128M           1
 130         * 30           4               3       2-4 GB          5
 131         * 48           4               3       8-16 GB         8
 132         * 32           8               4       1-2 GB          4
 133         * 32           8               4       0.9-1GB         4
 134         * 10           16              5       <128M           1
 135         * 40           16              5       900M            4
 136         * 70           64              7       2-4 GB          5
 137         * 84           64              7       4-8 GB          6
 138         * 108          512             9       4-8 GB          6
 139         * 125          1024            10      8-16 GB         8
 140         * 125          1024            10      16-32 GB        9
 141         */
 142
 143        mem = zone->managed_pages >> (27 - PAGE_SHIFT);
 144
 145        threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 146
 147        /*
 148         * Maximum threshold is 125
 149         */
 150        threshold = min(125, threshold);
 151
 152        return threshold;
 153}
 154
 155/*
 156 * Refresh the thresholds for each zone.
 157 */
 158void refresh_zone_stat_thresholds(void)
 159{
 160        struct zone *zone;
 161        int cpu;
 162        int threshold;
 163
 164        for_each_populated_zone(zone) {
 165                unsigned long max_drift, tolerate_drift;
 166
 167                threshold = calculate_normal_threshold(zone);
 168
 169                for_each_online_cpu(cpu)
 170                        per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 171                                                        = threshold;
 172
 173                /*
 174                 * Only set percpu_drift_mark if there is a danger that
 175                 * NR_FREE_PAGES reports the low watermark is ok when in fact
 176                 * the min watermark could be breached by an allocation
 177                 */
 178                tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
 179                max_drift = num_online_cpus() * threshold;
 180                if (max_drift > tolerate_drift)
 181                        zone->percpu_drift_mark = high_wmark_pages(zone) +
 182                                        max_drift;
 183        }
 184}
 185
 186void set_pgdat_percpu_threshold(pg_data_t *pgdat,
 187                                int (*calculate_pressure)(struct zone *))
 188{
 189        struct zone *zone;
 190        int cpu;
 191        int threshold;
 192        int i;
 193
 194        for (i = 0; i < pgdat->nr_zones; i++) {
 195                zone = &pgdat->node_zones[i];
 196                if (!zone->percpu_drift_mark)
 197                        continue;
 198
 199                threshold = (*calculate_pressure)(zone);
 200                for_each_possible_cpu(cpu)
 201                        per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 202                                                        = threshold;
 203        }
 204}
 205
 206/*
 207 * For use when we know that interrupts are disabled.
 208 */
 209void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 210                                int delta)
 211{
 212        struct per_cpu_pageset __percpu *pcp = zone->pageset;
 213        s8 __percpu *p = pcp->vm_stat_diff + item;
 214        long x;
 215        long t;
 216
 217        x = delta + __this_cpu_read(*p);
 218
 219        t = __this_cpu_read(pcp->stat_threshold);
 220
 221        if (unlikely(x > t || x < -t)) {
 222                zone_page_state_add(x, zone, item);
 223                x = 0;
 224        }
 225        __this_cpu_write(*p, x);
 226}
 227EXPORT_SYMBOL(__mod_zone_page_state);
 228
 229/*
 230 * Optimized increment and decrement functions.
 231 *
 232 * These are only for a single page and therefore can take a struct page *
 233 * argument instead of struct zone *. This allows the inclusion of the code
 234 * generated for page_zone(page) into the optimized functions.
 235 *
 236 * No overflow check is necessary and therefore the differential can be
 237 * incremented or decremented in place which may allow the compilers to
 238 * generate better code.
 239 * The increment or decrement is known and therefore one boundary check can
 240 * be omitted.
 241 *
 242 * NOTE: These functions are very performance sensitive. Change only
 243 * with care.
 244 *
 245 * Some processors have inc/dec instructions that are atomic vs an interrupt.
 246 * However, the code must first determine the differential location in a zone
 247 * based on the processor number and then inc/dec the counter. There is no
 248 * guarantee without disabling preemption that the processor will not change
 249 * in between and therefore the atomicity vs. interrupt cannot be exploited
 250 * in a useful way here.
 251 */
 252void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 253{
 254        struct per_cpu_pageset __percpu *pcp = zone->pageset;
 255        s8 __percpu *p = pcp->vm_stat_diff + item;
 256        s8 v, t;
 257
 258        v = __this_cpu_inc_return(*p);
 259        t = __this_cpu_read(pcp->stat_threshold);
 260        if (unlikely(v > t)) {
 261                s8 overstep = t >> 1;
 262
 263                zone_page_state_add(v + overstep, zone, item);
 264                __this_cpu_write(*p, -overstep);
 265        }
 266}
 267
 268void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 269{
 270        __inc_zone_state(page_zone(page), item);
 271}
 272EXPORT_SYMBOL(__inc_zone_page_state);
 273
 274void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 275{
 276        struct per_cpu_pageset __percpu *pcp = zone->pageset;
 277        s8 __percpu *p = pcp->vm_stat_diff + item;
 278        s8 v, t;
 279
 280        v = __this_cpu_dec_return(*p);
 281        t = __this_cpu_read(pcp->stat_threshold);
 282        if (unlikely(v < - t)) {
 283                s8 overstep = t >> 1;
 284
 285                zone_page_state_add(v - overstep, zone, item);
 286                __this_cpu_write(*p, overstep);
 287        }
 288}
 289
 290void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 291{
 292        __dec_zone_state(page_zone(page), item);
 293}
 294EXPORT_SYMBOL(__dec_zone_page_state);
 295
 296#ifdef CONFIG_HAVE_CMPXCHG_LOCAL
 297/*
 298 * If we have cmpxchg_local support then we do not need to incur the overhead
 299 * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
 300 *
 301 * mod_state() modifies the zone counter state through atomic per cpu
 302 * operations.
 303 *
 304 * Overstep mode specifies how overstep should handled:
 305 *     0       No overstepping
 306 *     1       Overstepping half of threshold
 307 *     -1      Overstepping minus half of threshold
 308*/
 309static inline void mod_state(struct zone *zone,
 310       enum zone_stat_item item, int delta, int overstep_mode)
 311{
 312        struct per_cpu_pageset __percpu *pcp = zone->pageset;
 313        s8 __percpu *p = pcp->vm_stat_diff + item;
 314        long o, n, t, z;
 315
 316        do {
 317                z = 0;  /* overflow to zone counters */
 318
 319                /*
 320                 * The fetching of the stat_threshold is racy. We may apply
 321                 * a counter threshold to the wrong the cpu if we get
 322                 * rescheduled while executing here. However, the next
 323                 * counter update will apply the threshold again and
 324                 * therefore bring the counter under the threshold again.
 325                 *
 326                 * Most of the time the thresholds are the same anyways
 327                 * for all cpus in a zone.
 328                 */
 329                t = this_cpu_read(pcp->stat_threshold);
 330
 331                o = this_cpu_read(*p);
 332                n = delta + o;
 333
 334                if (n > t || n < -t) {
 335                        int os = overstep_mode * (t >> 1) ;
 336
 337                        /* Overflow must be added to zone counters */
 338                        z = n + os;
 339                        n = -os;
 340                }
 341        } while (this_cpu_cmpxchg(*p, o, n) != o);
 342
 343        if (z)
 344                zone_page_state_add(z, zone, item);
 345}
 346
 347void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 348                                        int delta)
 349{
 350        mod_state(zone, item, delta, 0);
 351}
 352EXPORT_SYMBOL(mod_zone_page_state);
 353
 354void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 355{
 356        mod_state(zone, item, 1, 1);
 357}
 358
 359void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 360{
 361        mod_state(page_zone(page), item, 1, 1);
 362}
 363EXPORT_SYMBOL(inc_zone_page_state);
 364
 365void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 366{
 367        mod_state(page_zone(page), item, -1, -1);
 368}
 369EXPORT_SYMBOL(dec_zone_page_state);
 370#else
 371/*
 372 * Use interrupt disable to serialize counter updates
 373 */
 374void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 375                                        int delta)
 376{
 377        unsigned long flags;
 378
 379        local_irq_save(flags);
 380        __mod_zone_page_state(zone, item, delta);
 381        local_irq_restore(flags);
 382}
 383EXPORT_SYMBOL(mod_zone_page_state);
 384
 385void inc_zone_state(struct zone *zone, enum zone_stat_item item)
 386{
 387        unsigned long flags;
 388
 389        local_irq_save(flags);
 390        __inc_zone_state(zone, item);
 391        local_irq_restore(flags);
 392}
 393
 394void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 395{
 396        unsigned long flags;
 397        struct zone *zone;
 398
 399        zone = page_zone(page);
 400        local_irq_save(flags);
 401        __inc_zone_state(zone, item);
 402        local_irq_restore(flags);
 403}
 404EXPORT_SYMBOL(inc_zone_page_state);
 405
 406void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 407{
 408        unsigned long flags;
 409
 410        local_irq_save(flags);
 411        __dec_zone_page_state(page, item);
 412        local_irq_restore(flags);
 413}
 414EXPORT_SYMBOL(dec_zone_page_state);
 415#endif
 416
 417/*
 418 * Update the zone counters for one cpu.
 419 *
 420 * The cpu specified must be either the current cpu or a processor that
 421 * is not online. If it is the current cpu then the execution thread must
 422 * be pinned to the current cpu.
 423 *
 424 * Note that refresh_cpu_vm_stats strives to only access
 425 * node local memory. The per cpu pagesets on remote zones are placed
 426 * in the memory local to the processor using that pageset. So the
 427 * loop over all zones will access a series of cachelines local to
 428 * the processor.
 429 *
 430 * The call to zone_page_state_add updates the cachelines with the
 431 * statistics in the remote zone struct as well as the global cachelines
 432 * with the global counters. These could cause remote node cache line
 433 * bouncing and will have to be only done when necessary.
 434 */
 435void refresh_cpu_vm_stats(int cpu)
 436{
 437        struct zone *zone;
 438        int i;
 439        int global_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 440
 441        for_each_populated_zone(zone) {
 442                struct per_cpu_pageset *p;
 443
 444                p = per_cpu_ptr(zone->pageset, cpu);
 445
 446                for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 447                        if (p->vm_stat_diff[i]) {
 448                                unsigned long flags;
 449                                int v;
 450
 451                                local_irq_save(flags);
 452                                v = p->vm_stat_diff[i];
 453                                p->vm_stat_diff[i] = 0;
 454                                local_irq_restore(flags);
 455                                atomic_long_add(v, &zone->vm_stat[i]);
 456                                global_diff[i] += v;
 457#ifdef CONFIG_NUMA
 458                                /* 3 seconds idle till flush */
 459                                p->expire = 3;
 460#endif
 461                        }
 462                cond_resched();
 463#ifdef CONFIG_NUMA
 464                /*
 465                 * Deal with draining the remote pageset of this
 466                 * processor
 467                 *
 468                 * Check if there are pages remaining in this pageset
 469                 * if not then there is nothing to expire.
 470                 */
 471                if (!p->expire || !p->pcp.count)
 472                        continue;
 473
 474                /*
 475                 * We never drain zones local to this processor.
 476                 */
 477                if (zone_to_nid(zone) == numa_node_id()) {
 478                        p->expire = 0;
 479                        continue;
 480                }
 481
 482                p->expire--;
 483                if (p->expire)
 484                        continue;
 485
 486                if (p->pcp.count)
 487                        drain_zone_pages(zone, &p->pcp);
 488#endif
 489        }
 490
 491        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 492                if (global_diff[i])
 493                        atomic_long_add(global_diff[i], &vm_stat[i]);
 494}
 495
 496/*
 497 * this is only called if !populated_zone(zone), which implies no other users of
 498 * pset->vm_stat_diff[] exsist.
 499 */
 500void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
 501{
 502        int i;
 503
 504        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 505                if (pset->vm_stat_diff[i]) {
 506                        int v = pset->vm_stat_diff[i];
 507                        pset->vm_stat_diff[i] = 0;
 508                        atomic_long_add(v, &zone->vm_stat[i]);
 509                        atomic_long_add(v, &vm_stat[i]);
 510                }
 511}
 512#endif
 513
 514#ifdef CONFIG_NUMA
 515/*
 516 * zonelist = the list of zones passed to the allocator
 517 * z        = the zone from which the allocation occurred.
 518 *
 519 * Must be called with interrupts disabled.
 520 *
 521 * When __GFP_OTHER_NODE is set assume the node of the preferred
 522 * zone is the local node. This is useful for daemons who allocate
 523 * memory on behalf of other processes.
 524 */
 525void zone_statistics(struct zone *preferred_zone, struct zone *z, gfp_t flags)
 526{
 527        if (z->zone_pgdat == preferred_zone->zone_pgdat) {
 528                __inc_zone_state(z, NUMA_HIT);
 529        } else {
 530                __inc_zone_state(z, NUMA_MISS);
 531                __inc_zone_state(preferred_zone, NUMA_FOREIGN);
 532        }
 533        if (z->node == ((flags & __GFP_OTHER_NODE) ?
 534                        preferred_zone->node : numa_node_id()))
 535                __inc_zone_state(z, NUMA_LOCAL);
 536        else
 537                __inc_zone_state(z, NUMA_OTHER);
 538}
 539#endif
 540
 541#ifdef CONFIG_COMPACTION
 542
 543struct contig_page_info {
 544        unsigned long free_pages;
 545        unsigned long free_blocks_total;
 546        unsigned long free_blocks_suitable;
 547};
 548
 549/*
 550 * Calculate the number of free pages in a zone, how many contiguous
 551 * pages are free and how many are large enough to satisfy an allocation of
 552 * the target size. Note that this function makes no attempt to estimate
 553 * how many suitable free blocks there *might* be if MOVABLE pages were
 554 * migrated. Calculating that is possible, but expensive and can be
 555 * figured out from userspace
 556 */
 557static void fill_contig_page_info(struct zone *zone,
 558                                unsigned int suitable_order,
 559                                struct contig_page_info *info)
 560{
 561        unsigned int order;
 562
 563        info->free_pages = 0;
 564        info->free_blocks_total = 0;
 565        info->free_blocks_suitable = 0;
 566
 567        for (order = 0; order < MAX_ORDER; order++) {
 568                unsigned long blocks;
 569
 570                /* Count number of free blocks */
 571                blocks = zone->free_area[order].nr_free;
 572                info->free_blocks_total += blocks;
 573
 574                /* Count free base pages */
 575                info->free_pages += blocks << order;
 576
 577                /* Count the suitable free blocks */
 578                if (order >= suitable_order)
 579                        info->free_blocks_suitable += blocks <<
 580                                                (order - suitable_order);
 581        }
 582}
 583
 584/*
 585 * A fragmentation index only makes sense if an allocation of a requested
 586 * size would fail. If that is true, the fragmentation index indicates
 587 * whether external fragmentation or a lack of memory was the problem.
 588 * The value can be used to determine if page reclaim or compaction
 589 * should be used
 590 */
 591static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
 592{
 593        unsigned long requested = 1UL << order;
 594
 595        if (!info->free_blocks_total)
 596                return 0;
 597
 598        /* Fragmentation index only makes sense when a request would fail */
 599        if (info->free_blocks_suitable)
 600                return -1000;
 601
 602        /*
 603         * Index is between 0 and 1 so return within 3 decimal places
 604         *
 605         * 0 => allocation would fail due to lack of memory
 606         * 1 => allocation would fail due to fragmentation
 607         */
 608        return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
 609}
 610
 611/* Same as __fragmentation index but allocs contig_page_info on stack */
 612int fragmentation_index(struct zone *zone, unsigned int order)
 613{
 614        struct contig_page_info info;
 615
 616        fill_contig_page_info(zone, order, &info);
 617        return __fragmentation_index(order, &info);
 618}
 619#endif
 620
 621#if defined(CONFIG_PROC_FS) || defined(CONFIG_COMPACTION)
 622#include <linux/proc_fs.h>
 623#include <linux/seq_file.h>
 624
 625static char * const migratetype_names[MIGRATE_TYPES] = {
 626        "Unmovable",
 627        "Reclaimable",
 628        "Movable",
 629        "Reserve",
 630#ifdef CONFIG_CMA
 631        "CMA",
 632#endif
 633#ifdef CONFIG_MEMORY_ISOLATION
 634        "Isolate",
 635#endif
 636};
 637
 638static void *frag_start(struct seq_file *m, loff_t *pos)
 639{
 640        pg_data_t *pgdat;
 641        loff_t node = *pos;
 642        for (pgdat = first_online_pgdat();
 643             pgdat && node;
 644             pgdat = next_online_pgdat(pgdat))
 645                --node;
 646
 647        return pgdat;
 648}
 649
 650static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 651{
 652        pg_data_t *pgdat = (pg_data_t *)arg;
 653
 654        (*pos)++;
 655        return next_online_pgdat(pgdat);
 656}
 657
 658static void frag_stop(struct seq_file *m, void *arg)
 659{
 660}
 661
 662/* Walk all the zones in a node and print using a callback */
 663static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 664                void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 665{
 666        struct zone *zone;
 667        struct zone *node_zones = pgdat->node_zones;
 668        unsigned long flags;
 669
 670        for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 671                if (!populated_zone(zone))
 672                        continue;
 673
 674                spin_lock_irqsave(&zone->lock, flags);
 675                print(m, pgdat, zone);
 676                spin_unlock_irqrestore(&zone->lock, flags);
 677        }
 678}
 679#endif
 680
 681#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 682#ifdef CONFIG_ZONE_DMA
 683#define TEXT_FOR_DMA(xx) xx "_dma",
 684#else
 685#define TEXT_FOR_DMA(xx)
 686#endif
 687
 688#ifdef CONFIG_ZONE_DMA32
 689#define TEXT_FOR_DMA32(xx) xx "_dma32",
 690#else
 691#define TEXT_FOR_DMA32(xx)
 692#endif
 693
 694#ifdef CONFIG_HIGHMEM
 695#define TEXT_FOR_HIGHMEM(xx) xx "_high",
 696#else
 697#define TEXT_FOR_HIGHMEM(xx)
 698#endif
 699
 700#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 701                                        TEXT_FOR_HIGHMEM(xx) xx "_movable",
 702
 703const char * const vmstat_text[] = {
 704        /* Zoned VM counters */
 705        "nr_free_pages",
 706        "nr_inactive_anon",
 707        "nr_active_anon",
 708        "nr_inactive_file",
 709        "nr_active_file",
 710        "nr_unevictable",
 711        "nr_mlock",
 712        "nr_anon_pages",
 713        "nr_mapped",
 714        "nr_file_pages",
 715        "nr_dirty",
 716        "nr_writeback",
 717        "nr_slab_reclaimable",
 718        "nr_slab_unreclaimable",
 719        "nr_page_table_pages",
 720        "nr_kernel_stack",
 721        "nr_unstable",
 722        "nr_bounce",
 723        "nr_vmscan_write",
 724        "nr_vmscan_immediate_reclaim",
 725        "nr_writeback_temp",
 726        "nr_isolated_anon",
 727        "nr_isolated_file",
 728        "nr_shmem",
 729        "nr_dirtied",
 730        "nr_written",
 731
 732#ifdef CONFIG_NUMA
 733        "numa_hit",
 734        "numa_miss",
 735        "numa_foreign",
 736        "numa_interleave",
 737        "numa_local",
 738        "numa_other",
 739#endif
 740        "nr_anon_transparent_hugepages",
 741        "nr_free_cma",
 742        "nr_dirty_threshold",
 743        "nr_dirty_background_threshold",
 744
 745#ifdef CONFIG_VM_EVENT_COUNTERS
 746        "pgpgin",
 747        "pgpgout",
 748        "pswpin",
 749        "pswpout",
 750
 751        TEXTS_FOR_ZONES("pgalloc")
 752
 753        "pgfree",
 754        "pgactivate",
 755        "pgdeactivate",
 756
 757        "pgfault",
 758        "pgmajfault",
 759
 760        TEXTS_FOR_ZONES("pgrefill")
 761        TEXTS_FOR_ZONES("pgsteal_kswapd")
 762        TEXTS_FOR_ZONES("pgsteal_direct")
 763        TEXTS_FOR_ZONES("pgscan_kswapd")
 764        TEXTS_FOR_ZONES("pgscan_direct")
 765        "pgscan_direct_throttle",
 766
 767#ifdef CONFIG_NUMA
 768        "zone_reclaim_failed",
 769#endif
 770        "pginodesteal",
 771        "slabs_scanned",
 772        "kswapd_inodesteal",
 773        "kswapd_low_wmark_hit_quickly",
 774        "kswapd_high_wmark_hit_quickly",
 775        "pageoutrun",
 776        "allocstall",
 777
 778        "pgrotated",
 779
 780#ifdef CONFIG_NUMA_BALANCING
 781        "numa_pte_updates",
 782        "numa_hint_faults",
 783        "numa_hint_faults_local",
 784        "numa_pages_migrated",
 785#endif
 786#ifdef CONFIG_MIGRATION
 787        "pgmigrate_success",
 788        "pgmigrate_fail",
 789#endif
 790#ifdef CONFIG_COMPACTION
 791        "compact_migrate_scanned",
 792        "compact_free_scanned",
 793        "compact_isolated",
 794        "compact_stall",
 795        "compact_fail",
 796        "compact_success",
 797#endif
 798
 799#ifdef CONFIG_HUGETLB_PAGE
 800        "htlb_buddy_alloc_success",
 801        "htlb_buddy_alloc_fail",
 802#endif
 803        "unevictable_pgs_culled",
 804        "unevictable_pgs_scanned",
 805        "unevictable_pgs_rescued",
 806        "unevictable_pgs_mlocked",
 807        "unevictable_pgs_munlocked",
 808        "unevictable_pgs_cleared",
 809        "unevictable_pgs_stranded",
 810
 811#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 812        "thp_fault_alloc",
 813        "thp_fault_fallback",
 814        "thp_collapse_alloc",
 815        "thp_collapse_alloc_failed",
 816        "thp_split",
 817        "thp_zero_page_alloc",
 818        "thp_zero_page_alloc_failed",
 819#endif
 820
 821#endif /* CONFIG_VM_EVENTS_COUNTERS */
 822};
 823#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 824
 825
 826#ifdef CONFIG_PROC_FS
 827static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 828                                                struct zone *zone)
 829{
 830        int order;
 831
 832        seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 833        for (order = 0; order < MAX_ORDER; ++order)
 834                seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 835        seq_putc(m, '\n');
 836}
 837
 838/*
 839 * This walks the free areas for each zone.
 840 */
 841static int frag_show(struct seq_file *m, void *arg)
 842{
 843        pg_data_t *pgdat = (pg_data_t *)arg;
 844        walk_zones_in_node(m, pgdat, frag_show_print);
 845        return 0;
 846}
 847
 848static void pagetypeinfo_showfree_print(struct seq_file *m,
 849                                        pg_data_t *pgdat, struct zone *zone)
 850{
 851        int order, mtype;
 852
 853        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 854                seq_printf(m, "Node %4d, zone %8s, type %12s ",
 855                                        pgdat->node_id,
 856                                        zone->name,
 857                                        migratetype_names[mtype]);
 858                for (order = 0; order < MAX_ORDER; ++order) {
 859                        unsigned long freecount = 0;
 860                        struct free_area *area;
 861                        struct list_head *curr;
 862
 863                        area = &(zone->free_area[order]);
 864
 865                        list_for_each(curr, &area->free_list[mtype])
 866                                freecount++;
 867                        seq_printf(m, "%6lu ", freecount);
 868                }
 869                seq_putc(m, '\n');
 870        }
 871}
 872
 873/* Print out the free pages at each order for each migatetype */
 874static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 875{
 876        int order;
 877        pg_data_t *pgdat = (pg_data_t *)arg;
 878
 879        /* Print header */
 880        seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 881        for (order = 0; order < MAX_ORDER; ++order)
 882                seq_printf(m, "%6d ", order);
 883        seq_putc(m, '\n');
 884
 885        walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 886
 887        return 0;
 888}
 889
 890static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 891                                        pg_data_t *pgdat, struct zone *zone)
 892{
 893        int mtype;
 894        unsigned long pfn;
 895        unsigned long start_pfn = zone->zone_start_pfn;
 896        unsigned long end_pfn = zone_end_pfn(zone);
 897        unsigned long count[MIGRATE_TYPES] = { 0, };
 898
 899        for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 900                struct page *page;
 901
 902                if (!pfn_valid(pfn))
 903                        continue;
 904
 905                page = pfn_to_page(pfn);
 906
 907                /* Watch for unexpected holes punched in the memmap */
 908                if (!memmap_valid_within(pfn, page, zone))
 909                        continue;
 910
 911                mtype = get_pageblock_migratetype(page);
 912
 913                if (mtype < MIGRATE_TYPES)
 914                        count[mtype]++;
 915        }
 916
 917        /* Print counts */
 918        seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 919        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 920                seq_printf(m, "%12lu ", count[mtype]);
 921        seq_putc(m, '\n');
 922}
 923
 924/* Print out the free pages at each order for each migratetype */
 925static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 926{
 927        int mtype;
 928        pg_data_t *pgdat = (pg_data_t *)arg;
 929
 930        seq_printf(m, "\n%-23s", "Number of blocks type ");
 931        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 932                seq_printf(m, "%12s ", migratetype_names[mtype]);
 933        seq_putc(m, '\n');
 934        walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 935
 936        return 0;
 937}
 938
 939/*
 940 * This prints out statistics in relation to grouping pages by mobility.
 941 * It is expensive to collect so do not constantly read the file.
 942 */
 943static int pagetypeinfo_show(struct seq_file *m, void *arg)
 944{
 945        pg_data_t *pgdat = (pg_data_t *)arg;
 946
 947        /* check memoryless node */
 948        if (!node_state(pgdat->node_id, N_MEMORY))
 949                return 0;
 950
 951        seq_printf(m, "Page block order: %d\n", pageblock_order);
 952        seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 953        seq_putc(m, '\n');
 954        pagetypeinfo_showfree(m, pgdat);
 955        pagetypeinfo_showblockcount(m, pgdat);
 956
 957        return 0;
 958}
 959
 960static const struct seq_operations fragmentation_op = {
 961        .start  = frag_start,
 962        .next   = frag_next,
 963        .stop   = frag_stop,
 964        .show   = frag_show,
 965};
 966
 967static int fragmentation_open(struct inode *inode, struct file *file)
 968{
 969        return seq_open(file, &fragmentation_op);
 970}
 971
 972static const struct file_operations fragmentation_file_operations = {
 973        .open           = fragmentation_open,
 974        .read           = seq_read,
 975        .llseek         = seq_lseek,
 976        .release        = seq_release,
 977};
 978
 979static const struct seq_operations pagetypeinfo_op = {
 980        .start  = frag_start,
 981        .next   = frag_next,
 982        .stop   = frag_stop,
 983        .show   = pagetypeinfo_show,
 984};
 985
 986static int pagetypeinfo_open(struct inode *inode, struct file *file)
 987{
 988        return seq_open(file, &pagetypeinfo_op);
 989}
 990
 991static const struct file_operations pagetypeinfo_file_ops = {
 992        .open           = pagetypeinfo_open,
 993        .read           = seq_read,
 994        .llseek         = seq_lseek,
 995        .release        = seq_release,
 996};
 997
 998static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 999                                                        struct zone *zone)
1000{
1001        int i;
1002        seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1003        seq_printf(m,
1004                   "\n  pages free     %lu"
1005                   "\n        min      %lu"
1006                   "\n        low      %lu"
1007                   "\n        high     %lu"
1008                   "\n        scanned  %lu"
1009                   "\n        spanned  %lu"
1010                   "\n        present  %lu"
1011                   "\n        managed  %lu",
1012                   zone_page_state(zone, NR_FREE_PAGES),
1013                   min_wmark_pages(zone),
1014                   low_wmark_pages(zone),
1015                   high_wmark_pages(zone),
1016                   zone->pages_scanned,
1017                   zone->spanned_pages,
1018                   zone->present_pages,
1019                   zone->managed_pages);
1020
1021        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1022                seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
1023                                zone_page_state(zone, i));
1024
1025        seq_printf(m,
1026                   "\n        protection: (%lu",
1027                   zone->lowmem_reserve[0]);
1028        for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1029                seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
1030        seq_printf(m,
1031                   ")"
1032                   "\n  pagesets");
1033        for_each_online_cpu(i) {
1034                struct per_cpu_pageset *pageset;
1035
1036                pageset = per_cpu_ptr(zone->pageset, i);
1037                seq_printf(m,
1038                           "\n    cpu: %i"
1039                           "\n              count: %i"
1040                           "\n              high:  %i"
1041                           "\n              batch: %i",
1042                           i,
1043                           pageset->pcp.count,
1044                           pageset->pcp.high,
1045                           pageset->pcp.batch);
1046#ifdef CONFIG_SMP
1047                seq_printf(m, "\n  vm stats threshold: %d",
1048                                pageset->stat_threshold);
1049#endif
1050        }
1051        seq_printf(m,
1052                   "\n  all_unreclaimable: %u"
1053                   "\n  start_pfn:         %lu"
1054                   "\n  inactive_ratio:    %u",
1055                   zone->all_unreclaimable,
1056                   zone->zone_start_pfn,
1057                   zone->inactive_ratio);
1058        seq_putc(m, '\n');
1059}
1060
1061/*
1062 * Output information about zones in @pgdat.
1063 */
1064static int zoneinfo_show(struct seq_file *m, void *arg)
1065{
1066        pg_data_t *pgdat = (pg_data_t *)arg;
1067        walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1068        return 0;
1069}
1070
1071static const struct seq_operations zoneinfo_op = {
1072        .start  = frag_start, /* iterate over all zones. The same as in
1073                               * fragmentation. */
1074        .next   = frag_next,
1075        .stop   = frag_stop,
1076        .show   = zoneinfo_show,
1077};
1078
1079static int zoneinfo_open(struct inode *inode, struct file *file)
1080{
1081        return seq_open(file, &zoneinfo_op);
1082}
1083
1084static const struct file_operations proc_zoneinfo_file_operations = {
1085        .open           = zoneinfo_open,
1086        .read           = seq_read,
1087        .llseek         = seq_lseek,
1088        .release        = seq_release,
1089};
1090
1091enum writeback_stat_item {
1092        NR_DIRTY_THRESHOLD,
1093        NR_DIRTY_BG_THRESHOLD,
1094        NR_VM_WRITEBACK_STAT_ITEMS,
1095};
1096
1097static void *vmstat_start(struct seq_file *m, loff_t *pos)
1098{
1099        unsigned long *v;
1100        int i, stat_items_size;
1101
1102        if (*pos >= ARRAY_SIZE(vmstat_text))
1103                return NULL;
1104        stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1105                          NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1106
1107#ifdef CONFIG_VM_EVENT_COUNTERS
1108        stat_items_size += sizeof(struct vm_event_state);
1109#endif
1110
1111        v = kmalloc(stat_items_size, GFP_KERNEL);
1112        m->private = v;
1113        if (!v)
1114                return ERR_PTR(-ENOMEM);
1115        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1116                v[i] = global_page_state(i);
1117        v += NR_VM_ZONE_STAT_ITEMS;
1118
1119        global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1120                            v + NR_DIRTY_THRESHOLD);
1121        v += NR_VM_WRITEBACK_STAT_ITEMS;
1122
1123#ifdef CONFIG_VM_EVENT_COUNTERS
1124        all_vm_events(v);
1125        v[PGPGIN] /= 2;         /* sectors -> kbytes */
1126        v[PGPGOUT] /= 2;
1127#endif
1128        return (unsigned long *)m->private + *pos;
1129}
1130
1131static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1132{
1133        (*pos)++;
1134        if (*pos >= ARRAY_SIZE(vmstat_text))
1135                return NULL;
1136        return (unsigned long *)m->private + *pos;
1137}
1138
1139static int vmstat_show(struct seq_file *m, void *arg)
1140{
1141        unsigned long *l = arg;
1142        unsigned long off = l - (unsigned long *)m->private;
1143
1144        seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1145        return 0;
1146}
1147
1148static void vmstat_stop(struct seq_file *m, void *arg)
1149{
1150        kfree(m->private);
1151        m->private = NULL;
1152}
1153
1154static const struct seq_operations vmstat_op = {
1155        .start  = vmstat_start,
1156        .next   = vmstat_next,
1157        .stop   = vmstat_stop,
1158        .show   = vmstat_show,
1159};
1160
1161static int vmstat_open(struct inode *inode, struct file *file)
1162{
1163        return seq_open(file, &vmstat_op);
1164}
1165
1166static const struct file_operations proc_vmstat_file_operations = {
1167        .open           = vmstat_open,
1168        .read           = seq_read,
1169        .llseek         = seq_lseek,
1170        .release        = seq_release,
1171};
1172#endif /* CONFIG_PROC_FS */
1173
1174#ifdef CONFIG_SMP
1175static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1176int sysctl_stat_interval __read_mostly = HZ;
1177
1178static void vmstat_update(struct work_struct *w)
1179{
1180        refresh_cpu_vm_stats(smp_processor_id());
1181        schedule_delayed_work(&__get_cpu_var(vmstat_work),
1182                round_jiffies_relative(sysctl_stat_interval));
1183}
1184
1185static void __cpuinit start_cpu_timer(int cpu)
1186{
1187        struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1188
1189        INIT_DEFERRABLE_WORK(work, vmstat_update);
1190        schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1191}
1192
1193/*
1194 * Use the cpu notifier to insure that the thresholds are recalculated
1195 * when necessary.
1196 */
1197static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1198                unsigned long action,
1199                void *hcpu)
1200{
1201        long cpu = (long)hcpu;
1202
1203        switch (action) {
1204        case CPU_ONLINE:
1205        case CPU_ONLINE_FROZEN:
1206                refresh_zone_stat_thresholds();
1207                start_cpu_timer(cpu);
1208                node_set_state(cpu_to_node(cpu), N_CPU);
1209                break;
1210        case CPU_DOWN_PREPARE:
1211        case CPU_DOWN_PREPARE_FROZEN:
1212                cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1213                per_cpu(vmstat_work, cpu).work.func = NULL;
1214                break;
1215        case CPU_DOWN_FAILED:
1216        case CPU_DOWN_FAILED_FROZEN:
1217                start_cpu_timer(cpu);
1218                break;
1219        case CPU_DEAD:
1220        case CPU_DEAD_FROZEN:
1221                refresh_zone_stat_thresholds();
1222                break;
1223        default:
1224                break;
1225        }
1226        return NOTIFY_OK;
1227}
1228
1229static struct notifier_block __cpuinitdata vmstat_notifier =
1230        { &vmstat_cpuup_callback, NULL, 0 };
1231#endif
1232
1233static int __init setup_vmstat(void)
1234{
1235#ifdef CONFIG_SMP
1236        int cpu;
1237
1238        register_cpu_notifier(&vmstat_notifier);
1239
1240        for_each_online_cpu(cpu)
1241                start_cpu_timer(cpu);
1242#endif
1243#ifdef CONFIG_PROC_FS
1244        proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1245        proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1246        proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1247        proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1248#endif
1249        return 0;
1250}
1251module_init(setup_vmstat)
1252
1253#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1254#include <linux/debugfs.h>
1255
1256
1257/*
1258 * Return an index indicating how much of the available free memory is
1259 * unusable for an allocation of the requested size.
1260 */
1261static int unusable_free_index(unsigned int order,
1262                                struct contig_page_info *info)
1263{
1264        /* No free memory is interpreted as all free memory is unusable */
1265        if (info->free_pages == 0)
1266                return 1000;
1267
1268        /*
1269         * Index should be a value between 0 and 1. Return a value to 3
1270         * decimal places.
1271         *
1272         * 0 => no fragmentation
1273         * 1 => high fragmentation
1274         */
1275        return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1276
1277}
1278
1279static void unusable_show_print(struct seq_file *m,
1280                                        pg_data_t *pgdat, struct zone *zone)
1281{
1282        unsigned int order;
1283        int index;
1284        struct contig_page_info info;
1285
1286        seq_printf(m, "Node %d, zone %8s ",
1287                                pgdat->node_id,
1288                                zone->name);
1289        for (order = 0; order < MAX_ORDER; ++order) {
1290                fill_contig_page_info(zone, order, &info);
1291                index = unusable_free_index(order, &info);
1292                seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1293        }
1294
1295        seq_putc(m, '\n');
1296}
1297
1298/*
1299 * Display unusable free space index
1300 *
1301 * The unusable free space index measures how much of the available free
1302 * memory cannot be used to satisfy an allocation of a given size and is a
1303 * value between 0 and 1. The higher the value, the more of free memory is
1304 * unusable and by implication, the worse the external fragmentation is. This
1305 * can be expressed as a percentage by multiplying by 100.
1306 */
1307static int unusable_show(struct seq_file *m, void *arg)
1308{
1309        pg_data_t *pgdat = (pg_data_t *)arg;
1310
1311        /* check memoryless node */
1312        if (!node_state(pgdat->node_id, N_MEMORY))
1313                return 0;
1314
1315        walk_zones_in_node(m, pgdat, unusable_show_print);
1316
1317        return 0;
1318}
1319
1320static const struct seq_operations unusable_op = {
1321        .start  = frag_start,
1322        .next   = frag_next,
1323        .stop   = frag_stop,
1324        .show   = unusable_show,
1325};
1326
1327static int unusable_open(struct inode *inode, struct file *file)
1328{
1329        return seq_open(file, &unusable_op);
1330}
1331
1332static const struct file_operations unusable_file_ops = {
1333        .open           = unusable_open,
1334        .read           = seq_read,
1335        .llseek         = seq_lseek,
1336        .release        = seq_release,
1337};
1338
1339static void extfrag_show_print(struct seq_file *m,
1340                                        pg_data_t *pgdat, struct zone *zone)
1341{
1342        unsigned int order;
1343        int index;
1344
1345        /* Alloc on stack as interrupts are disabled for zone walk */
1346        struct contig_page_info info;
1347
1348        seq_printf(m, "Node %d, zone %8s ",
1349                                pgdat->node_id,
1350                                zone->name);
1351        for (order = 0; order < MAX_ORDER; ++order) {
1352                fill_contig_page_info(zone, order, &info);
1353                index = __fragmentation_index(order, &info);
1354                seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1355        }
1356
1357        seq_putc(m, '\n');
1358}
1359
1360/*
1361 * Display fragmentation index for orders that allocations would fail for
1362 */
1363static int extfrag_show(struct seq_file *m, void *arg)
1364{
1365        pg_data_t *pgdat = (pg_data_t *)arg;
1366
1367        walk_zones_in_node(m, pgdat, extfrag_show_print);
1368
1369        return 0;
1370}
1371
1372static const struct seq_operations extfrag_op = {
1373        .start  = frag_start,
1374        .next   = frag_next,
1375        .stop   = frag_stop,
1376        .show   = extfrag_show,
1377};
1378
1379static int extfrag_open(struct inode *inode, struct file *file)
1380{
1381        return seq_open(file, &extfrag_op);
1382}
1383
1384static const struct file_operations extfrag_file_ops = {
1385        .open           = extfrag_open,
1386        .read           = seq_read,
1387        .llseek         = seq_lseek,
1388        .release        = seq_release,
1389};
1390
1391static int __init extfrag_debug_init(void)
1392{
1393        struct dentry *extfrag_debug_root;
1394
1395        extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1396        if (!extfrag_debug_root)
1397                return -ENOMEM;
1398
1399        if (!debugfs_create_file("unusable_index", 0444,
1400                        extfrag_debug_root, NULL, &unusable_file_ops))
1401                goto fail;
1402
1403        if (!debugfs_create_file("extfrag_index", 0444,
1404                        extfrag_debug_root, NULL, &extfrag_file_ops))
1405                goto fail;
1406
1407        return 0;
1408fail:
1409        debugfs_remove_recursive(extfrag_debug_root);
1410        return -ENOMEM;
1411}
1412
1413module_init(extfrag_debug_init);
1414#endif
1415
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