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->present_pages >> (27 - PAGE_SHIFT);
 146
 147        threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 148
 149        /*
 150         * Maximum threshold is 125
 151         */
 152        threshold = min(125, threshold);
 153
 154        return threshold;
 155}
 156
 157/*
 158 * Refresh the thresholds for each zone.
 159 */
 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        "Isolate",
 632};
 633
 634static void *frag_start(struct seq_file *m, loff_t *pos)
 635{
 636        pg_data_t *pgdat;
 637        loff_t node = *pos;
 638        for (pgdat = first_online_pgdat();
 639             pgdat && node;
 640             pgdat = next_online_pgdat(pgdat))
 641                --node;
 642
 643        return pgdat;
 644}
 645
 646static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
 647{
 648        pg_data_t *pgdat = (pg_data_t *)arg;
 649
 650        (*pos)++;
 651        return next_online_pgdat(pgdat);
 652}
 653
 654static void frag_stop(struct seq_file *m, void *arg)
 655{
 656}
 657
 658/* Walk all the zones in a node and print using a callback */
 659static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
 660                void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
 661{
 662        struct zone *zone;
 663        struct zone *node_zones = pgdat->node_zones;
 664        unsigned long flags;
 665
 666        for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
 667                if (!populated_zone(zone))
 668                        continue;
 669
 670                spin_lock_irqsave(&zone->lock, flags);
 671                print(m, pgdat, zone);
 672                spin_unlock_irqrestore(&zone->lock, flags);
 673        }
 674}
 675#endif
 676
 677#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
 678#ifdef CONFIG_ZONE_DMA
 679#define TEXT_FOR_DMA(xx) xx "_dma",
 680#else
 681#define TEXT_FOR_DMA(xx)
 682#endif
 683
 684#ifdef CONFIG_ZONE_DMA32
 685#define TEXT_FOR_DMA32(xx) xx "_dma32",
 686#else
 687#define TEXT_FOR_DMA32(xx)
 688#endif
 689
 690#ifdef CONFIG_HIGHMEM
 691#define TEXT_FOR_HIGHMEM(xx) xx "_high",
 692#else
 693#define TEXT_FOR_HIGHMEM(xx)
 694#endif
 695
 696#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
 697                                        TEXT_FOR_HIGHMEM(xx) xx "_movable",
 698
 699const char * const vmstat_text[] = {
 700        /* Zoned VM counters */
 701        "nr_free_pages",
 702        "nr_inactive_anon",
 703        "nr_active_anon",
 704        "nr_inactive_file",
 705        "nr_active_file",
 706        "nr_unevictable",
 707        "nr_mlock",
 708        "nr_anon_pages",
 709        "nr_mapped",
 710        "nr_file_pages",
 711        "nr_dirty",
 712        "nr_writeback",
 713        "nr_slab_reclaimable",
 714        "nr_slab_unreclaimable",
 715        "nr_page_table_pages",
 716        "nr_kernel_stack",
 717        "nr_unstable",
 718        "nr_bounce",
 719        "nr_vmscan_write",
 720        "nr_vmscan_immediate_reclaim",
 721        "nr_writeback_temp",
 722        "nr_isolated_anon",
 723        "nr_isolated_file",
 724        "nr_shmem",
 725        "nr_dirtied",
 726        "nr_written",
 727
 728#ifdef CONFIG_NUMA
 729        "numa_hit",
 730        "numa_miss",
 731        "numa_foreign",
 732        "numa_interleave",
 733        "numa_local",
 734        "numa_other",
 735#endif
 736        "nr_anon_transparent_hugepages",
 737        "nr_free_cma",
 738        "nr_dirty_threshold",
 739        "nr_dirty_background_threshold",
 740
 741#ifdef CONFIG_VM_EVENT_COUNTERS
 742        "pgpgin",
 743        "pgpgout",
 744        "pswpin",
 745        "pswpout",
 746
 747        TEXTS_FOR_ZONES("pgalloc")
 748
 749        "pgfree",
 750        "pgactivate",
 751        "pgdeactivate",
 752
 753        "pgfault",
 754        "pgmajfault",
 755
 756        TEXTS_FOR_ZONES("pgrefill")
 757        TEXTS_FOR_ZONES("pgsteal_kswapd")
 758        TEXTS_FOR_ZONES("pgsteal_direct")
 759        TEXTS_FOR_ZONES("pgscan_kswapd")
 760        TEXTS_FOR_ZONES("pgscan_direct")
 761        "pgscan_direct_throttle",
 762
 763#ifdef CONFIG_NUMA
 764        "zone_reclaim_failed",
 765#endif
 766        "pginodesteal",
 767        "slabs_scanned",
 768        "kswapd_inodesteal",
 769        "kswapd_low_wmark_hit_quickly",
 770        "kswapd_high_wmark_hit_quickly",
 771        "kswapd_skip_congestion_wait",
 772        "pageoutrun",
 773        "allocstall",
 774
 775        "pgrotated",
 776
 777#ifdef CONFIG_NUMA_BALANCING
 778        "numa_pte_updates",
 779        "numa_hint_faults",
 780        "numa_hint_faults_local",
 781        "numa_pages_migrated",
 782#endif
 783#ifdef CONFIG_MIGRATION
 784        "pgmigrate_success",
 785        "pgmigrate_fail",
 786#endif
 787#ifdef CONFIG_COMPACTION
 788        "compact_migrate_scanned",
 789        "compact_free_scanned",
 790        "compact_isolated",
 791        "compact_stall",
 792        "compact_fail",
 793        "compact_success",
 794#endif
 795
 796#ifdef CONFIG_HUGETLB_PAGE
 797        "htlb_buddy_alloc_success",
 798        "htlb_buddy_alloc_fail",
 799#endif
 800        "unevictable_pgs_culled",
 801        "unevictable_pgs_scanned",
 802        "unevictable_pgs_rescued",
 803        "unevictable_pgs_mlocked",
 804        "unevictable_pgs_munlocked",
 805        "unevictable_pgs_cleared",
 806        "unevictable_pgs_stranded",
 807
 808#ifdef CONFIG_TRANSPARENT_HUGEPAGE
 809        "thp_fault_alloc",
 810        "thp_fault_fallback",
 811        "thp_collapse_alloc",
 812        "thp_collapse_alloc_failed",
 813        "thp_split",
 814        "thp_zero_page_alloc",
 815        "thp_zero_page_alloc_failed",
 816#endif
 817
 818#endif /* CONFIG_VM_EVENTS_COUNTERS */
 819};
 820#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
 821
 822
 823#ifdef CONFIG_PROC_FS
 824static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
 825                                                struct zone *zone)
 826{
 827        int order;
 828
 829        seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 830        for (order = 0; order < MAX_ORDER; ++order)
 831                seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
 832        seq_putc(m, '\n');
 833}
 834
 835/*
 836 * This walks the free areas for each zone.
 837 */
 838static int frag_show(struct seq_file *m, void *arg)
 839{
 840        pg_data_t *pgdat = (pg_data_t *)arg;
 841        walk_zones_in_node(m, pgdat, frag_show_print);
 842        return 0;
 843}
 844
 845static void pagetypeinfo_showfree_print(struct seq_file *m,
 846                                        pg_data_t *pgdat, struct zone *zone)
 847{
 848        int order, mtype;
 849
 850        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
 851                seq_printf(m, "Node %4d, zone %8s, type %12s ",
 852                                        pgdat->node_id,
 853                                        zone->name,
 854                                        migratetype_names[mtype]);
 855                for (order = 0; order < MAX_ORDER; ++order) {
 856                        unsigned long freecount = 0;
 857                        struct free_area *area;
 858                        struct list_head *curr;
 859
 860                        area = &(zone->free_area[order]);
 861
 862                        list_for_each(curr, &area->free_list[mtype])
 863                                freecount++;
 864                        seq_printf(m, "%6lu ", freecount);
 865                }
 866                seq_putc(m, '\n');
 867        }
 868}
 869
 870/* Print out the free pages at each order for each migatetype */
 871static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
 872{
 873        int order;
 874        pg_data_t *pgdat = (pg_data_t *)arg;
 875
 876        /* Print header */
 877        seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
 878        for (order = 0; order < MAX_ORDER; ++order)
 879                seq_printf(m, "%6d ", order);
 880        seq_putc(m, '\n');
 881
 882        walk_zones_in_node(m, pgdat, pagetypeinfo_showfree_print);
 883
 884        return 0;
 885}
 886
 887static void pagetypeinfo_showblockcount_print(struct seq_file *m,
 888                                        pg_data_t *pgdat, struct zone *zone)
 889{
 890        int mtype;
 891        unsigned long pfn;
 892        unsigned long start_pfn = zone->zone_start_pfn;
 893        unsigned long end_pfn = start_pfn + zone->spanned_pages;
 894        unsigned long count[MIGRATE_TYPES] = { 0, };
 895
 896        for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
 897                struct page *page;
 898
 899                if (!pfn_valid(pfn))
 900                        continue;
 901
 902                page = pfn_to_page(pfn);
 903
 904                /* Watch for unexpected holes punched in the memmap */
 905                if (!memmap_valid_within(pfn, page, zone))
 906                        continue;
 907
 908                mtype = get_pageblock_migratetype(page);
 909
 910                if (mtype < MIGRATE_TYPES)
 911                        count[mtype]++;
 912        }
 913
 914        /* Print counts */
 915        seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
 916        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 917                seq_printf(m, "%12lu ", count[mtype]);
 918        seq_putc(m, '\n');
 919}
 920
 921/* Print out the free pages at each order for each migratetype */
 922static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
 923{
 924        int mtype;
 925        pg_data_t *pgdat = (pg_data_t *)arg;
 926
 927        seq_printf(m, "\n%-23s", "Number of blocks type ");
 928        for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
 929                seq_printf(m, "%12s ", migratetype_names[mtype]);
 930        seq_putc(m, '\n');
 931        walk_zones_in_node(m, pgdat, pagetypeinfo_showblockcount_print);
 932
 933        return 0;
 934}
 935
 936/*
 937 * This prints out statistics in relation to grouping pages by mobility.
 938 * It is expensive to collect so do not constantly read the file.
 939 */
 940static int pagetypeinfo_show(struct seq_file *m, void *arg)
 941{
 942        pg_data_t *pgdat = (pg_data_t *)arg;
 943
 944        /* check memoryless node */
 945        if (!node_state(pgdat->node_id, N_MEMORY))
 946                return 0;
 947
 948        seq_printf(m, "Page block order: %d\n", pageblock_order);
 949        seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
 950        seq_putc(m, '\n');
 951        pagetypeinfo_showfree(m, pgdat);
 952        pagetypeinfo_showblockcount(m, pgdat);
 953
 954        return 0;
 955}
 956
 957static const struct seq_operations fragmentation_op = {
 958        .start  = frag_start,
 959        .next   = frag_next,
 960        .stop   = frag_stop,
 961        .show   = frag_show,
 962};
 963
 964static int fragmentation_open(struct inode *inode, struct file *file)
 965{
 966        return seq_open(file, &fragmentation_op);
 967}
 968
 969static const struct file_operations fragmentation_file_operations = {
 970        .open           = fragmentation_open,
 971        .read           = seq_read,
 972        .llseek         = seq_lseek,
 973        .release        = seq_release,
 974};
 975
 976static const struct seq_operations pagetypeinfo_op = {
 977        .start  = frag_start,
 978        .next   = frag_next,
 979        .stop   = frag_stop,
 980        .show   = pagetypeinfo_show,
 981};
 982
 983static int pagetypeinfo_open(struct inode *inode, struct file *file)
 984{
 985        return seq_open(file, &pagetypeinfo_op);
 986}
 987
 988static const struct file_operations pagetypeinfo_file_ops = {
 989        .open           = pagetypeinfo_open,
 990        .read           = seq_read,
 991        .llseek         = seq_lseek,
 992        .release        = seq_release,
 993};
 994
 995static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
 996                                                        struct zone *zone)
 997{
 998        int i;
 999        seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1000        seq_printf(m,
1001                   "\n  pages free     %lu"
1002                   "\n        min      %lu"
1003                   "\n        low      %lu"
1004                   "\n        high     %lu"
1005                   "\n        scanned  %lu"
1006                   "\n        spanned  %lu"
1007                   "\n        present  %lu"
1008                   "\n        managed  %lu",
1009                   zone_page_state(zone, NR_FREE_PAGES),
1010                   min_wmark_pages(zone),
1011                   low_wmark_pages(zone),
1012                   high_wmark_pages(zone),
1013                   zone->pages_scanned,
1014                   zone->spanned_pages,
1015                   zone->present_pages,
1016                   zone->managed_pages);
1017
1018        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1019                seq_printf(m, "\n    %-12s %lu", vmstat_text[i],
1020                                zone_page_state(zone, i));
1021
1022        seq_printf(m,
1023                   "\n        protection: (%lu",
1024                   zone->lowmem_reserve[0]);
1025        for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1026                seq_printf(m, ", %lu", zone->lowmem_reserve[i]);
1027        seq_printf(m,
1028                   ")"
1029                   "\n  pagesets");
1030        for_each_online_cpu(i) {
1031                struct per_cpu_pageset *pageset;
1032
1033                pageset = per_cpu_ptr(zone->pageset, i);
1034                seq_printf(m,
1035                           "\n    cpu: %i"
1036                           "\n              count: %i"
1037                           "\n              high:  %i"
1038                           "\n              batch: %i",
1039                           i,
1040                           pageset->pcp.count,
1041                           pageset->pcp.high,
1042                           pageset->pcp.batch);
1043#ifdef CONFIG_SMP
1044                seq_printf(m, "\n  vm stats threshold: %d",
1045                                pageset->stat_threshold);
1046#endif
1047        }
1048        seq_printf(m,
1049                   "\n  all_unreclaimable: %u"
1050                   "\n  start_pfn:         %lu"
1051                   "\n  inactive_ratio:    %u",
1052                   zone->all_unreclaimable,
1053                   zone->zone_start_pfn,
1054                   zone->inactive_ratio);
1055        seq_putc(m, '\n');
1056}
1057
1058/*
1059 * Output information about zones in @pgdat.
1060 */
1061static int zoneinfo_show(struct seq_file *m, void *arg)
1062{
1063        pg_data_t *pgdat = (pg_data_t *)arg;
1064        walk_zones_in_node(m, pgdat, zoneinfo_show_print);
1065        return 0;
1066}
1067
1068static const struct seq_operations zoneinfo_op = {
1069        .start  = frag_start, /* iterate over all zones. The same as in
1070                               * fragmentation. */
1071        .next   = frag_next,
1072        .stop   = frag_stop,
1073        .show   = zoneinfo_show,
1074};
1075
1076static int zoneinfo_open(struct inode *inode, struct file *file)
1077{
1078        return seq_open(file, &zoneinfo_op);
1079}
1080
1081static const struct file_operations proc_zoneinfo_file_operations = {
1082        .open           = zoneinfo_open,
1083        .read           = seq_read,
1084        .llseek         = seq_lseek,
1085        .release        = seq_release,
1086};
1087
1088enum writeback_stat_item {
1089        NR_DIRTY_THRESHOLD,
1090        NR_DIRTY_BG_THRESHOLD,
1091        NR_VM_WRITEBACK_STAT_ITEMS,
1092};
1093
1094static void *vmstat_start(struct seq_file *m, loff_t *pos)
1095{
1096        unsigned long *v;
1097        int i, stat_items_size;
1098
1099        if (*pos >= ARRAY_SIZE(vmstat_text))
1100                return NULL;
1101        stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1102                          NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1103
1104#ifdef CONFIG_VM_EVENT_COUNTERS
1105        stat_items_size += sizeof(struct vm_event_state);
1106#endif
1107
1108        v = kmalloc(stat_items_size, GFP_KERNEL);
1109        m->private = v;
1110        if (!v)
1111                return ERR_PTR(-ENOMEM);
1112        for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1113                v[i] = global_page_state(i);
1114        v += NR_VM_ZONE_STAT_ITEMS;
1115
1116        global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1117                            v + NR_DIRTY_THRESHOLD);
1118        v += NR_VM_WRITEBACK_STAT_ITEMS;
1119
1120#ifdef CONFIG_VM_EVENT_COUNTERS
1121        all_vm_events(v);
1122        v[PGPGIN] /= 2;         /* sectors -> kbytes */
1123        v[PGPGOUT] /= 2;
1124#endif
1125        return (unsigned long *)m->private + *pos;
1126}
1127
1128static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1129{
1130        (*pos)++;
1131        if (*pos >= ARRAY_SIZE(vmstat_text))
1132                return NULL;
1133        return (unsigned long *)m->private + *pos;
1134}
1135
1136static int vmstat_show(struct seq_file *m, void *arg)
1137{
1138        unsigned long *l = arg;
1139        unsigned long off = l - (unsigned long *)m->private;
1140
1141        seq_printf(m, "%s %lu\n", vmstat_text[off], *l);
1142        return 0;
1143}
1144
1145static void vmstat_stop(struct seq_file *m, void *arg)
1146{
1147        kfree(m->private);
1148        m->private = NULL;
1149}
1150
1151static const struct seq_operations vmstat_op = {
1152        .start  = vmstat_start,
1153        .next   = vmstat_next,
1154        .stop   = vmstat_stop,
1155        .show   = vmstat_show,
1156};
1157
1158static int vmstat_open(struct inode *inode, struct file *file)
1159{
1160        return seq_open(file, &vmstat_op);
1161}
1162
1163static const struct file_operations proc_vmstat_file_operations = {
1164        .open           = vmstat_open,
1165        .read           = seq_read,
1166        .llseek         = seq_lseek,
1167        .release        = seq_release,
1168};
1169#endif /* CONFIG_PROC_FS */
1170
1171#ifdef CONFIG_SMP
1172static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1173int sysctl_stat_interval __read_mostly = HZ;
1174
1175static void vmstat_update(struct work_struct *w)
1176{
1177        refresh_cpu_vm_stats(smp_processor_id());
1178        schedule_delayed_work(&__get_cpu_var(vmstat_work),
1179                round_jiffies_relative(sysctl_stat_interval));
1180}
1181
1182static void __cpuinit start_cpu_timer(int cpu)
1183{
1184        struct delayed_work *work = &per_cpu(vmstat_work, cpu);
1185
1186        INIT_DEFERRABLE_WORK(work, vmstat_update);
1187        schedule_delayed_work_on(cpu, work, __round_jiffies_relative(HZ, cpu));
1188}
1189
1190/*
1191 * Use the cpu notifier to insure that the thresholds are recalculated
1192 * when necessary.
1193 */
1194static int __cpuinit vmstat_cpuup_callback(struct notifier_block *nfb,
1195                unsigned long action,
1196                void *hcpu)
1197{
1198        long cpu = (long)hcpu;
1199
1200        switch (action) {
1201        case CPU_ONLINE:
1202        case CPU_ONLINE_FROZEN:
1203                refresh_zone_stat_thresholds();
1204                start_cpu_timer(cpu);
1205                node_set_state(cpu_to_node(cpu), N_CPU);
1206                break;
1207        case CPU_DOWN_PREPARE:
1208        case CPU_DOWN_PREPARE_FROZEN:
1209                cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1210                per_cpu(vmstat_work, cpu).work.func = NULL;
1211                break;
1212        case CPU_DOWN_FAILED:
1213        case CPU_DOWN_FAILED_FROZEN:
1214                start_cpu_timer(cpu);
1215                break;
1216        case CPU_DEAD:
1217        case CPU_DEAD_FROZEN:
1218                refresh_zone_stat_thresholds();
1219                break;
1220        default:
1221                break;
1222        }
1223        return NOTIFY_OK;
1224}
1225
1226static struct notifier_block __cpuinitdata vmstat_notifier =
1227        { &vmstat_cpuup_callback, NULL, 0 };
1228#endif
1229
1230static int __init setup_vmstat(void)
1231{
1232#ifdef CONFIG_SMP
1233        int cpu;
1234
1235        register_cpu_notifier(&vmstat_notifier);
1236
1237        for_each_online_cpu(cpu)
1238                start_cpu_timer(cpu);
1239#endif
1240#ifdef CONFIG_PROC_FS
1241        proc_create("buddyinfo", S_IRUGO, NULL, &fragmentation_file_operations);
1242        proc_create("pagetypeinfo", S_IRUGO, NULL, &pagetypeinfo_file_ops);
1243        proc_create("vmstat", S_IRUGO, NULL, &proc_vmstat_file_operations);
1244        proc_create("zoneinfo", S_IRUGO, NULL, &proc_zoneinfo_file_operations);
1245#endif
1246        return 0;
1247}
1248module_init(setup_vmstat)
1249
1250#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1251#include <linux/debugfs.h>
1252
1253
1254/*
1255 * Return an index indicating how much of the available free memory is
1256 * unusable for an allocation of the requested size.
1257 */
1258static int unusable_free_index(unsigned int order,
1259                                struct contig_page_info *info)
1260{
1261        /* No free memory is interpreted as all free memory is unusable */
1262        if (info->free_pages == 0)
1263                return 1000;
1264
1265        /*
1266         * Index should be a value between 0 and 1. Return a value to 3
1267         * decimal places.
1268         *
1269         * 0 => no fragmentation
1270         * 1 => high fragmentation
1271         */
1272        return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
1273
1274}
1275
1276static void unusable_show_print(struct seq_file *m,
1277                                        pg_data_t *pgdat, struct zone *zone)
1278{
1279        unsigned int order;
1280        int index;
1281        struct contig_page_info info;
1282
1283        seq_printf(m, "Node %d, zone %8s ",
1284                                pgdat->node_id,
1285                                zone->name);
1286        for (order = 0; order < MAX_ORDER; ++order) {
1287                fill_contig_page_info(zone, order, &info);
1288                index = unusable_free_index(order, &info);
1289                seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1290        }
1291
1292        seq_putc(m, '\n');
1293}
1294
1295/*
1296 * Display unusable free space index
1297 *
1298 * The unusable free space index measures how much of the available free
1299 * memory cannot be used to satisfy an allocation of a given size and is a
1300 * value between 0 and 1. The higher the value, the more of free memory is
1301 * unusable and by implication, the worse the external fragmentation is. This
1302 * can be expressed as a percentage by multiplying by 100.
1303 */
1304static int unusable_show(struct seq_file *m, void *arg)
1305{
1306        pg_data_t *pgdat = (pg_data_t *)arg;
1307
1308        /* check memoryless node */
1309        if (!node_state(pgdat->node_id, N_MEMORY))
1310                return 0;
1311
1312        walk_zones_in_node(m, pgdat, unusable_show_print);
1313
1314        return 0;
1315}
1316
1317static const struct seq_operations unusable_op = {
1318        .start  = frag_start,
1319        .next   = frag_next,
1320        .stop   = frag_stop,
1321        .show   = unusable_show,
1322};
1323
1324static int unusable_open(struct inode *inode, struct file *file)
1325{
1326        return seq_open(file, &unusable_op);
1327}
1328
1329static const struct file_operations unusable_file_ops = {
1330        .open           = unusable_open,
1331        .read           = seq_read,
1332        .llseek         = seq_lseek,
1333        .release        = seq_release,
1334};
1335
1336static void extfrag_show_print(struct seq_file *m,
1337                                        pg_data_t *pgdat, struct zone *zone)
1338{
1339        unsigned int order;
1340        int index;
1341
1342        /* Alloc on stack as interrupts are disabled for zone walk */
1343        struct contig_page_info info;
1344
1345        seq_printf(m, "Node %d, zone %8s ",
1346                                pgdat->node_id,
1347                                zone->name);
1348        for (order = 0; order < MAX_ORDER; ++order) {
1349                fill_contig_page_info(zone, order, &info);
1350                index = __fragmentation_index(order, &info);
1351                seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
1352        }
1353
1354        seq_putc(m, '\n');
1355}
1356
1357/*
1358 * Display fragmentation index for orders that allocations would fail for
1359 */
1360static int extfrag_show(struct seq_file *m, void *arg)
1361{
1362        pg_data_t *pgdat = (pg_data_t *)arg;
1363
1364        walk_zones_in_node(m, pgdat, extfrag_show_print);
1365
1366        return 0;
1367}
1368
1369static const struct seq_operations extfrag_op = {
1370        .start  = frag_start,
1371        .next   = frag_next,
1372        .stop   = frag_stop,
1373        .show   = extfrag_show,
1374};
1375
1376static int extfrag_open(struct inode *inode, struct file *file)
1377{
1378        return seq_open(file, &extfrag_op);
1379}
1380
1381static const struct file_operations extfrag_file_ops = {
1382        .open           = extfrag_open,
1383        .read           = seq_read,
1384        .llseek         = seq_lseek,
1385        .release        = seq_release,
1386};
1387
1388static int __init extfrag_debug_init(void)
1389{
1390        struct dentry *extfrag_debug_root;
1391
1392        extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
1393        if (!extfrag_debug_root)
1394                return -ENOMEM;
1395
1396        if (!debugfs_create_file("unusable_index", 0444,
1397                        extfrag_debug_root, NULL, &unusable_file_ops))
1398                goto fail;
1399
1400        if (!debugfs_create_file("extfrag_index", 0444,
1401                        extfrag_debug_root, NULL, &extfrag_file_ops))
1402                goto fail;
1403
1404        return 0;
1405fail:
1406        debugfs_remove_recursive(extfrag_debug_root);
1407        return -ENOMEM;
1408}
1409
1410module_init(extfrag_debug_init);
1411#endif
1412
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